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 1891 
 
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Cornell University 
 Library 
 
 The original of tiiis bool< is in 
 tine Cornell University Library. 
 
 There are no known copyright restrictions in 
 the United States on the use of the text. 
 
 http://www.archive.org/details/cu31924015367661 
 
THE PRESERVATION 
 
 OF 
 
 STRUCTURAL TIMBER 
 
McGraw-Hill DookCoittpatiy 
 
 Puj6Cts/iers qf3oo£§/br 
 
 Electrical World TlieEngineei-ing andMining Journal 
 Engineering Record Engineering News 
 
 CailwayA^e Gazette American Machinist 
 
 Signal EngiriGer American Engineer 
 
 ElectricUailway Journal Coal Age 
 
 M?tallttrgical and Chemical Engineering Power 
 
 -IT 
 
THE PEESERVATION 
 
 OF 
 
 STRUCTURAL TIMBER 
 
 BY 
 HOWARD F. WEISS 
 
 DIBECTOB, FOBEST PRODUCTS LABORATORY, U. B. FOREST SERVICE 
 HONORARY MEMBER, AMERICAN WOOD PBESERVERS' ASSOCIATION 
 
 FiEST Edition 
 
 McGRAW-HILL BOOK COMPANY, Inc. 
 239 WEST 39TH STREET, NEW YORK 
 
 6 BOUVERIE STREET, LONDON, E. C. 
 
 1915 
 
 E.V. 
 
Copyright, 1914, by the 
 McGraw-Hill Book Company, Inc. 
 
 THE. MAPLE. PHBSS.YO»K. PA 
 
FATHBB AND MOTHER 
 
 THIS BOOK 
 
 IS 
 
 AFFECTIONATBLT DEDICATED 
 
PREFACE 
 
 The wood-preservation industry is one of those which is aid- 
 ing in the great movement for efficiency in operation and in the 
 the conservation of our natural resources. Practically unknown 
 in our country but a half century ago, its growth, especially in 
 the last decade, has been exceedingly rapid until there are now 
 nearly 100 plants in operation turning out over 125,000,000 cubic 
 feet of treated wood annually. Too much credit for this splendid 
 development cannot be given to men who like Dr. Hermann von 
 Schrenk have by their ability, knowledge, and persistence brought 
 the importance of preserving wood to the attention of the Ameri- 
 can people and successfully accomplished a mass of practical 
 results. There is every reason to believe that the growth of the 
 industry has by no means reached its climax, for there are thou- 
 sands of feet of structural timber used each year that are not being 
 treated but which should and eventually will be. 
 
 In an industry which has grown so rapidly and is' unique in 
 that a long time must elapse before the efficiency of many of its 
 processes are known, it is but natural that many perplexing prob- 
 lems should arise. The wood preservation industry certainly 
 has its just share of them, and although splendid progress has 
 been made, much yet remains to be learned; in fact, accurate 
 knowledge is just in its infancy. The whole art is permeated with 
 contradictory evidence and opinions so that it is exceedingly 
 difficult for the layman seeking advice to become other than con- 
 fused. 
 
 During the past nine years it has been my good fortune to be 
 thrown in personal contact with many of these problems and to 
 study them over our entire country. While so doing, the need 
 for a book on the subject has been repeatedly called to my atten- 
 tion, for while there are excellent works on given phases of wood 
 preservation, none apparently systematically covers the subject 
 in its broad aspect. It has been necessary to consult a large 
 number of separate publications to secure such data — a process 
 most tedious and unsatisfactory in this day of straight-line opera- 
 tion. Furthermore, it is thought a textbook on timber preserva- 
 
viii PREFACE 
 
 tion will be of help to students in forestry and engineering schools, 
 where a knowledge of wood utilization is desirable and often 
 necessary. 
 
 In the following pages, taken largely from lecture notes pre- 
 pared by the author for the civil engineering students at the 
 University of Wisconsin, it has been the aim to present reliable 
 information of fundamental importance. It is hoped that they 
 will be found of value and use to engineers, foresters, lumbermen, 
 students and all those interested in this subject and that this 
 effort may assist in raising still higher the enviable position 
 already held by the wood-preserving industry. 
 
 The author certainly wishes to acknowledge his indebtedness 
 to the U. S. Forest Service, from the publications and illustrations 
 of which he has very heavily drawn; to his friends engaged in 
 commercially treating timber, especially Mr. F. J. Angier, Mr. 
 Carl G. Crawford, and Mr. J. B. Card, whose generous assistance 
 has added much to this book; and to various associations and 
 societies from whose proceedings data have been taken. 
 
 H. F. W. 
 
 Madison, Wisconsin, 
 October 1, 1914. 
 
CONTENTS 
 
 Page 
 
 Pbepacb . . . . vii 
 
 List or Plates . . . xiii 
 
 CHAPTER I 
 
 Introduction . . 1 
 
 Definition of wood preservation — Importance of wood preservation 
 as an American industry — Present standing of the wood preserving 
 industry in the United States — Conserving our timber supply — 
 Effect of wood preservation on forest management — History of 
 wood preservation in Egypt, Europe, United States. 
 
 CHAPTER II 
 
 Factors Which Cause the Deterioration op Structural Timber. 15 
 Discussion of their relative importance — Decay — Insects — The 
 pole borer — Marine borers — Xylotrya, Nausitoria and Teredo — 
 The Phola — Mechanical abrasion — Fire — Minor factors — Alkaline 
 soils — Birds' — Sap stain. 
 
 CHAPTER III 
 
 The Effect of the Structure op Wood upon its Injection with 
 
 Preservatives 31 
 
 Effect of density upon absorption — Absorption by the cell walls — 
 The effect of sapwood and heartwood upon injection — The effect of 
 summerwood and springwood upon injection — The effect of vessels 
 or "pores" on the treatment of wood — The effect of tyloses on 
 the treatment of wood — The effect of resin ducts on the treatment 
 of wood — The effect of pits upon injection — The effect of cell slits 
 upon penetration — The effect of the chemical composition of the 
 cell wall upon absorption. 
 
 CHAPTER IV 
 
 The Preparation op Timber for its Preservative Treatment . 40 
 The cutting season — Peeling timber — Seasoning timber — Open-air 
 seasoning — Hot-air seasoning — Seasoning in saturated steam — 
 Seasoning in superheated steam — Seasoning in oil — Soaking timber 
 in water preparatory to seasoning it. 
 
X CONTENTS 
 
 CHAPTER V 
 
 Page 
 
 Pkocesses Used in Protecting Wood from Decay 50 
 
 Superficial processes — Charring — Brush treatments — Dipping — 
 Impregnation processes — Non-pressure processes — Kyanizing proc- 
 ess — Open-tank processes — Seeley process — Giussani process — 
 Pressure processes — Bethell (Full-cell Creosote) process — Boiling 
 process — Buehler process — A. C. W. process — Lowry process — 
 Rueping process — Burnett process — Rutgers process — Card process 
 — Wellhouse process — Allardyce process. 
 
 CHAPTER VI 
 
 Preservatives Used in Protecting Wood prom Decay . ... 64 
 Properties of eflScient preservatives — Water-soluble preservatives 
 — Copper sulphate — Mercuric chloride — Sodium fluoride — Zinc 
 chloride — Crude oils — Creosotes — Coal-tar creosote — Water-gas- 
 tar creosote — Wood-tar creosote — Mixed coal-tar creosotes — 
 Source of tars — Distillation of creosote from tars — Paints and 
 stains. 
 
 CHAPTER VII 
 
 The Construction and Operation op Wood Preserving Plants . . 89 
 Open-tank plants — Pressure plants — The retort house — Retorts 
 (cylinders) — Retort thermometer — Retort gauges — Anchors and 
 "turtles" — Retort coils — Guard rails — Retort doors — Retort lag- 
 ging — The pump house or room — The machine shop or room — The 
 boiler house — Yard — ^Loading dock — Methods of transferring 
 material in the yard — Cylinder cars — Measuring, mixing, working, 
 and storage tanks — Gauges and scales — Piping — Shower baths — 
 Inspector's laboraTtory— Fire protection — ^Lighting equipment — 
 Sawmill and block equipment — Tie boring and adzing machines — 
 The operation of pressure plants — The effect of the vacuum — The 
 effect of air pressure — The effect of pressure on the preservative — 
 Some common errors and difficulties in operating pressure plants — 
 Difficulty of measuring volume of charge — Expansion of creosote — 
 Expansion of cylinder — Compression of the oil and wood — 
 " Kickback " of preservative — Expansion of wood — Extent of possi- 
 ble errors — Purity of the preservative — Pollution of streams — 
 Inspection of treatments — Cost of pressure plants. 
 
 CHAPTER VIII 
 
 Prolonging the Lipe op Cross Ties prom Decay and Abrasion. . 128 
 Selection of species — Hewed versus sawed ties — Bearing afforded 
 tie-plates and rails — Uniformity in volume — Waste of material — 
 Form of cross-ties — Stacking ties for seasoning — Grouping ties to 
 secure uniform treatment — Species of wood — Proportion of sap- 
 wood — Moisture content — Cutting season — Conditions of growth 
 
CONTENTS xi 
 
 Page 
 
 — Protection from abrasion — Tie-plates — Spikes — Adzing and 
 boring ties — The selection of processes for treating ties — Cost of 
 treating ties — Economy in treating ties — Need for test tracks. 
 
 CHAPTER IX 
 
 Prolonging the Life op Poles and Cross Arms prom Decay and 
 
 Insects 156 
 
 Poles — Selection of species — Manufacture of poles — Methods of 
 seasoning — Methods of treatment and their selection — Setting in 
 crushed stone or concrete — Charring — Brush treatments — Open- 
 tank butt treatments — Entire impregnation — Boucherie process — 
 Kyan process — Re-enforcing decayed poles — Cost of treatment — 
 Economy of treatment. Crosss Arms — Selection of species — The 
 manufacture of cross arms — Methods of seasoning — Methods of 
 treatment and their selection — Cost of treatment — Economy of 
 treatment. 
 
 CHAPTER X 
 
 Prolonging the Life op Fence Posts prom Decay 172 
 
 Selection of species — Method and time of cutting posts — Method of 
 seasoning — Methods of treatment and their selection — Setting 
 posts in stones — Setting posts upside down — Charring the butt — 
 Dipping in crude oil and charring — Diagonal holes filled with pre- 
 servative — Brush treatments — Dipping treatments — Impregnation 
 treatments — Pitch streaks — Cost of treatment — Economy of treat- 
 ment. 
 
 CHAPTER XI 
 
 Prolonging the Lipe op Piling and Boats prom Decay and Marine 
 
 Borers 181 
 
 Selection of species — The manufacture of piling — Methods of 
 seasoning — Methods of treatment and their selection — Bark left on 
 piles — Plank coating — Nail coating — Metal coating — Burlap coat- 
 ings — Cement casings — Electrolysis-rlmpregnation with coal-tar 
 creosote — Cost of treating piling — Economy of treatments — The 
 preservative treatment of wooden boats. 
 
 CHAPTER XII 
 
 Prolonging the Lipe op Mine Timbers 188 
 
 Selection of species — The manufacture of mine timbers — Methods 
 of seasoning — Methods of treatment and their selection, rnine ties, 
 mine props, square sets, lagging — The treatment of mine timbers in 
 relation to fire — Cost of treatments — Economy of treatments. 
 
xii CONTENTS 
 
 CHAPTER XIII 
 
 Page 
 
 Prolonging the Life of Paving Blocks 195 
 
 Progress of wood paving — Selection of species — The manufacture 
 of paving blocks — Methods of treatment — Troubles experienced 
 with wood block paving — Slipperiness — Exudation of oil — Ex- 
 pansion of the blocks — Method of laying wood blocks — Cost of 
 treatment — Advantages of wood block pavements — Wood blocks 
 for barns, factories, etc. 
 
 CHAPTER XIV 
 
 Prolonging the Life op Shingles 205 
 
 Selection of species — Methods of treating shingles, against decay, 
 against fire — Cost of treating shingles. 
 
 CHAPTER XV 
 
 Prolonging the Life of Lumber and Logs . 205 
 
 Methods of treating lumber for rough construction — Methods of 
 treating lumber for buildings, greenhouses and cars — Methods of 
 preserving logs from decay — Methods of treating log cabins and 
 rustic furniture. 
 
 CHAPTER XVI 
 
 The Protection of Timber from Fire 213 
 
 The theory of rendering wood fire retardant — Superficial processes 
 — Impregnation processes — Chemicals used — Commercial treat- 
 ment — Tests to determine the inflammability of timber: shaving 
 test, crib test, spot test, electric furnace — Cost of rendering wood 
 non-combustible — The effect of zinc chloride and creosote on the 
 inflammability of wood. 
 
 CHAPTER XVII 
 
 The Protection of Wood prom Minor Destructive Agents 221 
 
 Alkaline soils — Birds — Sap stain — Sand storms. 
 
 CHAPTER XVIII 
 
 The Strength and Electrolysis of Treated Timber 224 
 
 The effect of air seasoning on the strength of wood — The effect of 
 steaming on the strength of wood — The effect of boiling wood in 
 creosote upon its strength — The effect of preservatives on the 
 strength of wood, creosote, zinc chloride, crude oil — The effect of 
 temperature on the strength of wood — The effect of pressure on the 
 strength of wood — The effect of various treatments on the strength 
 of wood — The electrical resistance of wood treated with creosote 
 and zinc chloride. 
 
CONTENTS xiii 
 
 CHAPTER XIX 
 
 Page 
 
 The Use of Stjestitutes for Treated Timber 243 
 
 Substitutes for wood ties — Substitutes for wood poles — Substitutes 
 for wood piling — Substitutes for wood posts — Substitutes for wood 
 mine timbers — Substitutes for wood bridges — Substitute for woo i 
 in buildings and cars — Substitutes for wood hingles — Substitutes 
 for wood conduits and pipes. 
 
 CHAPTER XX 
 
 Appendices 249 
 
 Minor wood preserving processes — Thilmany process, B-M process, 
 Goltra process, Hasselmann process, Creo-resinate process Robbins 
 process, Powell process, Creoaire process, Vulcanizing process, 
 Cresol-calcium process. 
 
 Patented, proprietary, and minor wood preservatives used in the 
 United States — Cresol calcium, S. P. F. Carbolineum, Avenarius 
 Carbolineum, C. A. Wood Preserver, Timberasphalt, Preservol, 
 Copperized oil, sodium silicate, Spirittine, B. M. Preservative, 
 water-gas-tar creosote, Holzhelfer, wood creosote, sodium fluoride, 
 Aczol, Sapwood Antiseptic, N. S. Special, Imperial Wood Pre- 
 servative, Kreodone, Locustine, Creoline. 
 
 List of manufacturers of zinc chloride in the United States — ^List 
 of manufacturers of creosote in the United States — ^List of wood 
 preserving plants in the United States — ^List of fireproofing plants 
 in the United States — The amount of wood, preservatives used in 
 the United States — The amount of timber treated in the United 
 States — ^List of companies in the United States equipped to build 
 wood-preserving plants — Specifications for the analysis of creosote 
 adopted by, the American Railway Engineering Association, the 
 National Electric Light Association, the United States Forest Serv- 
 ice — Method for determining the amount of moisture in creosote 
 and creosoted wood — The durability of American! timbers — ^List of 
 U. S.' patents in wood preservation — Method of analyzing zinc 
 chloride — Records on the life of timbers, mine timbers, paving 
 blocks, poles, cross-ties. 
 
 Index 305 
 
LIST OF PLATES 
 
 Frontispiece. — Wood Preservation Section of the Forest Products 
 
 Laboratory maintained by the U, S. Forest Service in co-operation 
 
 with the University of Wisconsin, Madison, Wis. . Frontis. 
 
 Facing page 
 
 Plate I 8-9 
 
 Fig. A. — -A stand of young lodgepole pine in Idaho. 
 
 Fig. B.— Egyptian coffin dating from the XII dynasty (2000-1788 
 
 B. C). The only restorations are three cleats on the bottom of the 
 
 coffin, otherwise it is in almost perfect preservation. 
 Fig. C — ^Lentinus lepidens. 
 Fig. D. — Lenizites sepiaria. 
 
 Plate II. . . . 18-19 
 
 Fig. A. — A red oak tie attacked by a wood destroying fungus 
 
 (Stereum fasciatum, Schw.). 
 Fig. B. — (1) The pole borer: male and female beetles. (2) Young 
 
 larvae. 
 Fig. C. — Gallery of the pole borer. 
 
 Fig. D. — Mines of the pole borer near the surface of the ground. 
 Plate III .... .... 26-27 
 
 Pig. A. — Cedar ties badly damaged by rail cutting. Upper section 
 
 shows tie without plate, lower section shows tie plate was too small. 
 Fig. B. — Poles destroyed by a sleet storm in Maryland, 1904. 
 Fig. C. — Results of a fire at the Arlington Manufacturing Company's 
 
 mill, Arlington, N. J. In rebuilding, wood beams were used 
 
 throughout. 
 Plate IV . . 34-35 
 
 Fig. A. — ^Longleaf pine boards piled solidly after one month's ex- 
 posure to sap stain fungi. Boards on left, untreated; boards on 
 
 right dipped in a weak solution of mercuric chloride. Note absence 
 
 of stain. 
 Fig. B. — Cross section through red oak — a "ring porous" wood. 
 
 Note arrangement of pores mostly in the spring wood. Note also 
 
 clearness of pores. X50. 
 Fig. C. — Cross-section through maple — a "diffuse porous" wood. 
 
 Note pores scattered through entire width of annual ring. X50. 
 Fig. D. — Cross-section through spruce — a "non-porous" wood. 
 
 Note absence of pores. Larger openings are "resin ducts" or cells. 
 
 X60. 
 Fig. E.— Cross-section through white oak. Note pores clogged with 
 
 "Tyloses." Compare with red oak. X50. 
 Fig. F. — Radial section through pine. Note bordered pits or "eyes," 
 
 also how fibers fit into one another. Vertical cells on extreme left 
 
 are medullary or "pith ray" cells. X250. 
 
 XV 
 
xri LIST OF PLATES 
 
 Facing page 
 Plate V 36-37 
 
 Fig. A. — Cross-section through a loblolly pine tie. Note wide rings 
 showing rapid growth, also note sharp transition of spring wood 
 and summerwood. 
 
 Pig. B. — Cross-sections through two longleaf pine stringers. Note 
 narrow rings especially in sapwood, showing slow growth. 
 
 Pig. C. — Cross-section through the summerwood of larch (greatly 
 magnified) showing slits in cell walls. 
 
 Fig. D. — Showing ease with which chestnut peels in the spring. 
 Plate VI 52-53 
 
 Pig. A. — Sections of creosoted piling showing effect of thin strips of 
 bark adhering to the wood. 
 
 Pig. B. — Brush treating poles. 
 
 Pig. C. — An open tank plant for treating the butts of poles — Cali- 
 fornia. 
 
 Pig. D. — Wood preserving plant of the C. B. & Q. R. R., Galesburg, 
 111. 
 Plate VII 90-91 
 
 Pig. A. — A post treating plant made of two barrels and an iron pipe. 
 
 Fig. B. — An open tank post treating plant — California. 
 
 Pig. C. — An open tank post treating plant. Note heat is furnished 
 by steam from threshing engine. Small cylindrical tank is for butt 
 treating in a hot bath; rectangular tank is for a cold bath. 
 
 Pig. D. — Open tank wood preserving plant for ties. The ties are car- 
 ried through the plant on an endless chain. 
 Plate VIII 92-93 
 
 Pig. A. — Small wood preserving plant designed by the U. S. Forest 
 Service in co-operation with the Louisiana Creosoting Co. 
 
 Pig. B. — View through a large treating cylinder. Note guard rails, 
 steam coils and track. International Creosoting and Construction 
 Company 
 
 Fig. C. — Spider door with independent sockets. 
 
 Pig. D. — Spider door with continuous socket support. 
 
 Pig. E. — Construction of a cast steel door. 
 Plate IX 96-97 . 
 
 Pig. A. — The construction of the collar and door in a pressure cylin- 
 der. Note cylinder track and guard rails. 
 
 Fig. B. — Construction of a door with cast steel rim and dished plate 
 steel head. 
 
 Fig. C. — Cylinder doors without hinges. Norfolk Creosoting Com- 
 pany. 
 
 Pig. D. — Pump room C. B. & Q. R. R. treating plant. Note 
 arrangement of gauges and control valves. 
 Plate X 100-101 
 
 Pig. A. — Chicago & Northwestern tie treating plant, Escanaba, 
 Mich. 
 
 Fig. B. — Tie treating plant of the Pennsylvania R. R. Note con- 
 crete loading dock with empty cylinder cars on top also manner of 
 unloading and piling ties for air seasoning. 
 
LIST OF PLATES xvii 
 
 Pacing page 
 
 Fig. C. — Unloading treated ties from cylinder buggies into gondolas 
 with a locomotive crane. Port Reading Creosoting Company. 
 
 Fig. D. — Overhead electric crane for loading timber into cylinder cars. 
 Gulf port Creosoting Co., Gulf port, Miss. 
 Plate XI 102-103 
 
 Fig. A. — Bolster car. Used for long timbers. 
 
 Fig. B. — A tie car. 
 
 Fig. C. — Mercury gauge for measuring the preservative in the meas- 
 uring tank. Baltimore & Ohio R. R. tie plant. 
 
 Fig. D. — Wood block treating plant of the Chicago Creosoting Co., 
 Terra Haute, Ind. Note vertical cylinders. 
 Plate XII 106-107 
 
 Fig. A. — Ties entering boring and adzing machine. 
 
 Fig. B. — Ties adzed and bored being pUed on the cylinder cars ready 
 for treatment. 
 
 Fig. C. — Section through an oak tie showing a cut and screw spike 
 driven in place. Note comparative distortion of wood fibers. 
 Plate XIII 132-133 
 
 Fig. A. — Method of hewing oak ties in Tennessee. Note waste. 
 
 Fig. B. — ^Rectangular cross ties — Standard form in the United States. 
 
 Fig. C. — ^Standard Prussian ties of Baltic pine. 
 
 Fig. D. — Triangular cross ties — Great Northern Ry. 
 Plate XIV . . ., 142-143 
 
 Fig. A. — A good method of piling ties for air seasoning. Port Read- 
 ing Creosoting Co. 
 
 Fig. B. — White oak ties seasoned to fast. 
 
 Pig. C. — Ties "protected" with wooden plates. Note plate crushed 
 into tie. 
 
 Fig. D. — Metal tie plate. 
 Plate XV 158-159 
 
 Fig. A. — Cedar poles piled for storage — Michigan. 
 
 Fig. B. — ^Poles properly piled for air seasoning — Black Forest, 
 Germany. 
 
 Fig. C. — -An open tank pole treating plant. A poor design; note 
 creosote evaporating from tanks. 
 
 Fig. D. — Creosoted poles for heavy construction — Hayes, England. 
 Plate XVI 164-165 
 
 Fig. A. — A boucherie pole treating plant — Ii\ilda, Germany. 
 
 Fig. B. — Partially decayed pole reinforced with a creosoted stub. 
 
 Fig. C. — Method of reinforcing a partially decayed pole with a con- 
 crete jacket. 
 Plate XVII 170-171 
 
 Fig. A. — Cross arms properly piled for air seasoning. 
 
 Fig. B.' — Creosoted cross arms just leaving the treating cylinder. 
 Norfolk Creosoting Co. 
 
 Fig. C. — Fence posts properly piled for air seasoning. 
 
 Fig. D. — Untreated lodgepole pine post set 4 years. Note decay at 
 the ground. 
 
xviii LIST OF PLATES 
 
 Facing page 
 
 Plate XVIII 182-183 
 
 Fig. A. — Pence posts dipped in crude oil and then charred. Note 
 
 good condition after 12 years service. 
 Fig. B. — Sections of creosoted piling. Note erratic penetrations of 
 
 creosote. 
 Pig. C. — Pile sheathed with zinc entirely destroyed by marine borers 
 
 — Pensacola, Fla. 
 Fig. D. — Piling protected with cement casings from attack by marine 
 borers — Pensacola, Ha. 
 Plate XIX. ... .... . . 186-187 
 
 Fig. A.^ — Sections of longleaf pine piles after 21 months' exposure to 
 the attack of marine borers at Gulfport, Miss. Section to the 
 right, untreated; section to the left impregnated with a crude oil. 
 Fig. B. — Untreated pine piles completely destroyed by marine wood 
 borers — Santa Rosa Island, Fla. 
 
 Plate XX ... . 192-193 
 
 Fig. A. — Gangway of treated mine timbers — Pottsville, Pa. 
 
 Fig. B. — Rank growth of fungus on mine timbers. 
 
 Fig. C. — Treated and untreated mine props. Treated prop to right 
 
 set at same time as failed untreated prop at left — Pennsylvania. 
 Fig. D. — Untreated mine props destroyed by decay and "squeeze," 
 — Pennsylvania. 
 
 Plate XXI ... 202-203 
 
 Fig. A. — A "popup " or failure in a street laid with creosoted blocks 
 
 due to their expansion. 
 Fig. 6. — Wood block pavements — grading the sand cushion and lay- 
 ing the blocks — Minneapolis, Minn. , 
 Fig. C. — Working the tar filler into the joints of a newly laid wood 
 
 block pavement. 
 Fig. D. — Pine beams in a building completely rotted in the ends after 
 30 years service — Madison, Wis. 
 Plate XXII . . . . 224r-225 
 
 Fig. A. — Type of soda dipping tank manufactured by the Lufkin 
 
 Foundry & Machine Co. 
 Fig. B. — Stake damaged by sand storms in southern California. 
 
 Compare portion in the ground with portion above ground. 
 Fig. C. — Section of an experimental track laid with steel ties. 
 Fig. D. — A fence of concrete posts — Madison, Wis. 
 Plate XXIII . . ... . . . . 246-247 
 
 Fig. A. — Concrete mine props — Pennsylvania. 
 
 Fig. B. — Indiana Tie Company's wood preserving plant, Joppa, 111. 
 Note depressed tracks and manner of running cylinder cars on 
 fiat cars for loading ties into box cars for shipment. 
 Fig. C. — Nest box used to protect poles and buildings from attack 
 
 by wood peckers. 
 Fig. D. — Wood dowels screwed into soft-wood ties as a protection 
 against spike cutting. 
 
THE PRESERVATION 
 OF STRUCTURAL TIMBER 
 
 CHAPTER I 
 INTRODUCTION 
 
 Definition of Wood Preservation. — Wood preservation may be 
 defined as the art of protecting structural timber from decay. 
 This is the common acceptance of the term. When considered 
 in its broadest aspect, however, it includes much more than this, 
 since decay is but one factor causing the destruction of wood. It 
 is in its broadest sense that the subject is discussed in this treatise, 
 because it is believed that the practice of protecting from deteri- 
 oration will broaden as wood increases in value. 
 
 In order to adequately treat the subject, wood preservation 
 will be defined as the art of protecting structural timber from 
 deterioration by destructive agents. The more common of these 
 are decay, insects, marine borers, mechanical abrasion, and fire. 
 It should be noted that the definition does not include the pro- 
 tection of trees, as the methods of doing this are entirely distinct 
 from those practised in protecting wood cut from the trees after 
 they have been felled. This distinction should be kept clearly 
 in mind. 
 
 Importance of Wood Preservation as an American Industry. — 
 In an undeveloped country destined for civilization extensive 
 forests are an obstruction which must be removed, because they 
 occupy land needed fpr agriculture. As long as a country is 
 heavily timbered, conservative methods of utilizing the timber 
 will rarely be practised. This condition prevailed in the United 
 States during its early history but exists no longer. Scientific 
 methods of managing forests as well as efficient methods of utiliz- 
 ing the timber cut from them, are now being practised. Both, 
 Ijowever, are still in their infancy but they are undergoing a rapid 
 application. These economic changes are excellently reflected 
 in the United States in the development of the wood preserving 
 industry. 
 
2 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 Present Standing of the Wood Preserving Industry in the 
 United States. — There are now about 90 wood preserving plants 
 in active operation in the United States representing a capitali- 
 zation of over $10,000,000 and turning out products worth about 
 $30,000,000 per year. TheSe plants use annually over 100,000,000 
 gallons of creosote costing over $7,000,000 and over 21,000,000 
 pounds of zinc chloride costing about $1,000,000. In addition, 
 about 3,500,000 gallons of various other preservatives are annu- 
 ally consumed representing a value of perhaps $1,250,000. The 
 total amount of wood treated approximates 126,000,000 cubic 
 feet per year, which is equivalent to the amount of wood produced 
 annually by about 10,000,000 acres of average American forest. 
 Since present methods of lumbering waste about 50 percent of 
 the wood grown, the amount of wood now annually treated repre- 
 sents a protection given to the annual output of approximately 
 20,000,000 acres of timberland. 
 
 To the above should be added several millions of dollars spent 
 each year in protecting timber from mechanical destruction and 
 about a quarter of a million protecting wood against fire. 
 
 Conserving our Timber Supply. — A natural result of the in- 
 creasing practice of preserving wood is to decrease the drain on 
 our forests and hence help to conserve our supply of timber. 
 This is offset in part by the growth of the country, demanding 
 more raw materials, so that no accurate estimate on the extent to 
 which wood preservation will ultimately decrease the demand 
 for structural* timber to be used for replacements can be given. 
 The author attempted such an estimate in 1909 for the National 
 Conservation Commission. Certain modifications now appear 
 advisable, although the estimate as then given has not been ma- 
 terially changed. This revised estimate is given in Table 1. It 
 attempts to show to what extent the demand on our forests can 
 be decreased if all timber placed in situations where it is liable to 
 deterioration were treated in some approved manner. For ex- 
 ample, we now use each year about 100,000,000 cross-ties to re- 
 place those which have worn out through decay, wear, and other 
 causes. If these ties were given an efiicient preservative treat- 
 ment, their life could be prolonged and in a few years the demand 
 for ties would decrease to about 42,000,000 annually instead of 
 100,000,000 as at present. Of course this neglects the ever in- 
 creasing demand for ties due to new construction. Estimating 
 along these lines, it appears that the application of efiicient pro- 
 
INTRODUCTION 3 
 
 tective measures to structural timber would decrease the drain 
 on our forests by almost 7,000,000,000 board feet annually, were 
 all such timber which is liable to deterioration protected. 
 
 Table 1. — Estimated Decrease in the Annual Cut op Timber which 
 
 WOULD Result were all Timber which is Subject 
 
 to Deterioration Properly Protected 
 
 Class 
 
 Estimated average 
 life in years 
 
 Estimated annual 
 replacements 
 
 Estimated 
 saving in 
 annual out 
 
 resulting 
 from proper 
 protection 
 
 (number) 
 
 Total 
 
 annual 
 
 saving 
 
 (MB M) 
 
 Untreated 
 
 Treated 
 
 Untreated 
 (number) 
 
 Treated 
 (number) 
 
 Ties 
 
 7 
 
 17 
 
 100,000,000 
 
 41,200,000 
 
 58,800,000 
 
 2,000,000 
 
 Poles 
 
 13 
 
 26 
 
 2,500,000 
 
 1,250,000 
 
 1,250,000 
 
 150,000 
 
 Posts 
 
 8 
 
 24 
 
 500,000,000 
 
 165,000,000 
 
 335,000,000 
 
 2,000,000 
 
 Piling 
 
 3 
 
 20 
 
 1,000,000 
 
 150,000 
 
 850,000 
 
 100,000 
 
 Mine props. 
 
 3 
 
 15 
 
 70,000,000» 
 
 14,000,000" 
 
 56,000,000" 
 
 275,000 
 
 Shingles 
 
 20 
 
 35 
 
 1,000' 
 
 600' 
 
 400' 
 
 400 
 
 Lumber. . . . 
 
 S 
 
 20 
 
 3,000,000' 
 
 1,200,000' 
 
 1,800,000' 
 
 1,800,000 
 
 Total 
 
 
 
 
 
 
 6,725,000 
 
 a = cubic feet. 6 = M B M. 
 
 That this shrinkage in the amount of timber cut from forests 
 due to the extended use of preservative treatment is not only a 
 logical but a real outgrowth is shown in part by the experience of 
 France. Although the French forests have been severely culled, 
 they still furnish about 3,000,000 ties annually. Approximately 
 2,500,000 are used each year for renewals, which number has been 
 steadily diminishing in spite of the fact that the total mileage of 
 the country has been increasing. ^ The practice of preservative 
 treatment in our country has been too recent to make its influence 
 on forest demands as yet apparent but that similar results will be 
 experienced cannot be doubted. 
 
 Effect of Wood Preservation on Forest Management.^En- 
 tirely apart from the problem of husbanding our forest resources 
 is the effect of treating timber on the practice of managing our 
 forests. By giving durability to woods which do not naturally 
 possess it, the practice of wood preservation will in many cases 
 
 1 H. Matheiu, Revue G^nSrale des Chemins de Fer, August, 1887. 
 
4 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 govern the manner in which certain forests will be composed and 
 managed. 
 
 Forestry teaches that trees grow according to defined onto- and 
 phylogeneric laws, like all other forms of life, and if these laws 
 are violated, destruction will inevitably follow. A layman, for 
 example, may not understand why a young tulip tree will not 
 grow in his dense maple grove. 
 
 The utilization of various kinds of timber has shown that some 
 combine more valuable properties for man's purposes than 
 others. A study of these properties has been brought about 
 chiefly through dire necessity. Starting with the cream, man 
 has been forced to the milk. . The gums, for instance, classed as 
 "tree weeds" a few years ago, are now eagerly sought and util- 
 ized. As a result of these two conditions, namely, the knowledge 
 of the laws of tree growth and the inherent superiority of certain 
 woods for commercial purposes, selected types of forests have been 
 evolved. In other words, man endeavors to eliminate the unde- 
 sirable species and foster the growth of those best fitted to his 
 needs. The mixed pine and beech forests of Germany may be 
 cited as an illustration. We have not reached this stage in the 
 United States, but with the ever increasing intensity of forest 
 management, nature's combinations will be eradicated, and in 
 their place will be developed man's idea of the Society of the Se- 
 lect. Nature's law which decrees, "Since no two organisms are 
 alike, one must be better adapted to its surroundings than the 
 other, and the less adapted must sooner or later perish," will be 
 changed to read: "Since no two organisms are alike, one must be 
 better adapted to man's needs than the other, and the less adapted 
 must sooner or later perish." This is an illustration from Forest 
 Ecology, which depicts man's disturbing influence in modifying 
 various forms of life to best meet his requirements. Thus the 
 American forest of the future will be radically different in kind as 
 well as in degree from those now existing. Of the forty odd 
 species of commercial trees now found in the Appalachians, it is 
 safe to state that not more than one-fourth will persist. Certain 
 trees, like the hemlock, will become commercially extinct, simply 
 because it will not pay to grow them. This is not a view into 
 the distant future; the careful selection of species is already 
 common practice in Europe, and even now is being actively 
 applied in our country. 
 
 As stated, the commercial extinction of certain American 
 
INTRODUCTION 5 
 
 trees and the restriction of others is inevitable, and will be 
 brought about because they lack certain specific qualities. 
 These are of two kinds: 
 
 1. Sylvical — the abundance and vitality of the seed; the re- 
 sistance of the young plants to insects, fire, and animals; their 
 adaptability to their environment; their rate of growth, etc., and 
 
 2. Commercial — the size, strength, weight and beauty of the 
 wood, its ease of workmanship, and its durability. 
 
 Of all these properties, durability is one of great practical mo- 
 ment and of direct bearing on this treatise. No method is 
 known whereby all kinds of wood can be satisfactorily treated 
 with preservatives. Fortunately, however, the species best 
 adapted to treatment are among the most abundant, and possess 
 certain sylvical and commercial properties which give them a 
 decided advantage over others. These properties briefly are: 
 The vitality and prolificacy of the seed, rapidity of growth, and 
 high percentage of sapwood. The following species may be 
 classed in this group: Bull, lodgepole, loblolly, shortleaf, jack 
 and scrub pines; cottonwood, red and scarlet oaks, silver and red 
 maples; white birch; buckeye; black and cotton gums. All of 
 these, with the possible exception of the bull and shortleaf pines 
 and cottonwood, are commonly classed as "inferior" species. 
 When a timbered area is cut or burned over, these are the com- 
 mercial species which usually first come in to reforest it. It 
 should be noted that their rate of growth soon culminates. None 
 of them are long lived, and none of them have durable wood. 
 The inherent characteristics of these trees are such as to render a 
 forest composed of them easy to propagate and manage. 
 
 Wood preservation thus affects the composition of certain 
 forests as the forests of the future will be grown for specific pur- 
 poses. White oak will be as rarely used for cross-ties as black 
 walnut now is for fence rails. Future stands of timber will often 
 be composed of those species whose wood without the application 
 of a chemical treatment would have such a limited demand that 
 they could not be grown at a profit. 
 
 Suppose that an individual or company has a tract of denuded 
 land upon which it is decided to grow timber. Should slow or 
 rapid growing species be planted? Which will pay better? Al- 
 most invariably the wood of the former is more durable than 
 that of the latter, but if figured on the basis of annual financial 
 profit, the advantages are usually in favor of the latter. An 
 
6 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 example may be cited : Loblolly pine in an index stand on a 70- 
 year rotation will yield about 33,000 feet B.M. per acre; longleaf 
 pine under similar conditions, on a 120-year rotation, will yield 
 about 25,000 feet B.M. Assuming the value of the land and the 
 cost of planting at $10 per acre, taxes 3 cents, fire protection 
 and management 2 cents per year, and interest 4 percent, 
 the total cost of growing the loblolly at the felling period will be 
 $174 and the longleaf $1244 per acre. The future stumpage 
 price of these species can only be predicted, but at the time the 
 trees were cut, suppose the value to be $8 per thousand feet B.M. 
 for loblolly and $13 for longleaf, or an advance in present prices 
 of over 300 percent for loblolly and 400 percent for longleaf. 
 The value of the crops per acre will then be respectively $264 
 and $325, or a total profit of $90 for the loblolly and a deficit of 
 $919 for the longleaf. Longleaf, in order to produce a profit 
 equal to the loblolly, would have to be worth about $54 per 
 thousand feet stumpage. At such a price it would be commerci- 
 ally prohibitive. In other words, longleaf pine can be grown only 
 at a loss. 
 
 In order to take a most favorable view of a question like the 
 above, let us assume that the land is worth only $1 an acre and 
 that the same yield will be obtained by natural reforestation. 
 Hence, there will be no cost for planting. Moreover, we will 
 assume no charge for protection. The cost of the crops per acre 
 will then be $26.50 for loblolly and $192.90 for longleaf, or net 
 profits respectively of $237 and $132 with an excess of $105 per 
 acre for loblolly pine. Similar examples would be found to exist 
 if other of our slow growing and more durable woods were com- 
 pared with those listed in the so-called "inferior" group. 
 
 Exceptions, of course, occur, notably with such species as 
 black locust, catalpa, osage orange, chestnut, and eucalypts, 
 which combine durability with rapidity of growth. But these 
 trees are of small size or poor form or are subject to insect or 
 fungus attack or are decidedly limited in distribution. Whenever 
 these species can be profitably grown their extension should by all 
 means be encouraged, because they combine many of those quali- 
 ties in strong demand and their subsequent treatment with 
 preservatives is not a necessity. That the use to which its 
 products will be put often controls the composition of a forest is 
 further shown in this country by the plantations of various rail- 
 roads. The Pennsylvania, for example, has planted large areas 
 
INTRODUCTION 7 
 
 to so-called "treatment woods," such as red oak in place of the 
 slower growing white oak and other more durable woods mentioned 
 above. The U. S. Forest Service is managing certain of its 
 lodgepole pine forests for the direct purpose of producing cross- 
 ties. Without preservation, it would not pay to use this pine for 
 ties because of its rapid decay. (See Plate I, Fig. A.) 
 
 Wood preservation enables trees removed' in thinning the forest 
 to be put to a higher use than for fuel and by so doing permits 
 thinnings to be more systematically and effectively made. 
 If a forest plantation is started with 1200 trees to the acre, it is 
 safe to assume that not more than 17 percent — or a total of 204 — 
 will remain for the final crop. Those removed will have been cut 
 in the several thinnings when the trees were yet immature, in 
 order to give room for the more thrifty trees. The revenue 
 derived from such thinnings is usually figured on the fuel value of 
 the wood. Such small trees, however, if cut for posts or even 
 poles, and treated, will have their value appreciably augmented, 
 so that thinnings can be made to yield a larger income. Sup- 
 pose the plantation is loblolly pine and the first thinning is made 
 at 20 years, 600 trees per acre being removed. These will be 
 about 3 inches in diameter and 20 feet high, hence too small to 
 be used advantageously even for fuel. The first thinning will 
 therefore represent a direct apparent loss, which, however, will 
 be recovered by the accelerated growth of the remaining trees. 
 The second thinning will be made at 40 years, and 400 trees will 
 be removed. These will have reached a diameter of 8 inches and 
 a height of 45 feet. If cut for fuel, they would yield about 13 
 cords worth about $1 per cord stumpage. If cut into posts, how- 
 ever, they would yield about 1600 worth at 2 cents each stump- 
 age a total of $32. Posts of this species, or more generally of 
 inferior species, are worth little unless treated, but when treated 
 their durability may equal or excell that of the more costly 
 varieties, so that it will often prove cheaper to use them. In- 
 creased profit derived from thinnings will enable them to be more 
 systematically and carefully made and thus the application of a 
 more intensive system of forest management is made possible. 
 The practicability of a forest working plan depends very largely 
 and in some cases entirely upon direct financial returns, and in 
 any case, if the plan can be made to produce such returns, it 
 will enable forest principles to be more readily applied. 
 
 Other things being equal, conservative lumbering pivots upon 
 
 %> 
 
8 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 the value of the top logs. Change this value and you change the 
 system of marketing. Wood preservation enables the top and 
 inferior logs to be used to better advantage than if left in the woods 
 to rot or sawed into lumber. By raising their value, it intensi- 
 fies the utilization of timber and fosters its more conservative use. 
 Thus the top logs of such trees as the yellow poplar, black walnut, 
 maple, birch, etc., possess so little value that they are often left 
 in the woods to rot, or when sawed into lumber are frequently 
 sold at a loss. For example, the value of lumber cut from 
 yellow birch logs in the Adirondacks in 1904, 14 inches or less in 
 diameter, was $9.37 per thousand. The cost of stumpage, log- 
 ging, and manufacturing was at the lowest figure $10.50 per thou- 
 sand. The operators therefore lost 11.13 per thousand on all 
 such logs removed. For beech the loss amounted to $1.80 per 
 thousand feet B.M. If these logs had been cut into railroad ties, 
 they would, at $5 per thousand stumpage and 15 cents each for 
 logging and manufacture, have cost about 32 cents each and sold 
 for245 cents each, or a net profit of about $3.90 per thousand feet 
 B.M. Untreated ties of this species have little use on account 
 of their rapid decay. Some lumber companies have already 
 realized the important part wood preservation is playing in their 
 operations and are now manufacturing their logs which are in- 
 ferior for lumber into ties. An effective system of forest manage- 
 ment will recognize this and will change the manner of harvest- 
 ing the timber so as to get greater returns from it. 
 
 Wood preservation accelerates the removal of fire-killed and 
 dead timber and enables areas so denuded to be more speedily 
 reforested and placed upon a profitable basis. Dead timber, 
 whether standing or down, decreases in value each year and land 
 encumbered with it can be likened to capital stock earning no 
 dividend but compelled to pay annuities. There are thousands 
 of acres of just such land in the United States. It is often im- 
 practicable to use such dead trees for lumber because of their 
 extensive checks, the stained condition of the wood, or holes 
 bored by insects. Furthermore, on account of rapid decay, the 
 wood may not be usable even for ties, mine props, etc. If 
 treated with preservatives much of this timber can be marketed. 
 Tests made by the author on fire-killed lodgepole pine in Idaho 
 proved it was in ideal condition for preservative treatment. 
 When cut for such purposes its stumpage value in comparison 
 with its former fuel value was raised about 60 percent. 
 
Plate I 
 
 Fig. a. — A stand of young Hodgepole pine in Idaho. (Forest Service photo.) 
 
 Fig. B.— Egyptian coffin dating from the XII dynasty (2000-1788 B. C). 
 The only restorations are three cleats on the bottom of the coffin, otherwise 
 it is in almost perfect preservation. (Photo through courtesy of the Metro- 
 politan Museum of Art, New York.) 
 
 {Facing page 8.) 
 
Plate I 
 
 mm^^ 
 
 
 
 
 
 Fig. C. — ^Lentinus lepidens. (Forest Service photo.) 
 
 Fig. D. — ^Lenizites sepiaria. (Photo through courtesy of C. J. Humphrey.) 
 
INTRODUCTION 9 
 
 History of Wood Preservation. Egypt'. — The earliest records 
 of the artificial preservation of organic bodies are found in Egyp- 
 tian history. The skill shown by the Egyptians in enbalming 
 bodies proves that they carried the art to a high state of perfec- 
 tion. Apparently the wooden coffins in which the bodies were 
 placed were given no special treatment, so that their durability 
 can be accounted for only by the exclusion from the wood of 
 sufficient moisture to allow the growth of wood-destroying 
 organisms. As sycamore was largely used in the construction 
 of these coffins, this furnishes excellent proof of the durability 
 of wood when it can be kept dry; in fact, in such a condition its 
 life is indefinite. (See Plate I, Fig. B.) 
 
 Such was not the case, however, in the preservation of the bod- 
 ies. It is definitely known that these were impregnated with 
 antiseptics, although the exact manner in which this was done is 
 still a matter of conjecture. From the writings of Herodotus 
 it appears that the bodies were first steeped in natrum (a natural 
 substance found in the briny lakes near Cairo and composed 
 principally of sodium sesqui-carbonate, sodium chloride, and so- 
 dium sulphate) for about 2 months, after which they were sub- 
 jected to a bituminous preparation, perhaps by boiling or baking 
 in an oven. Pettigrew extracted the preservatives from the heart 
 of a mummy which had been in a perfect state of preservation 
 for over 3000 years, and the heart at once putrified. Petti- 
 grew's experiments show that the mummies prepared in natrum 
 alone were not as well preserved as those in which solid resins or 
 bitumens were found. 
 
 Europe. — The quantities of wood used by the early Greeks 
 and Romans in their buildings and bridges caused them to meet 
 squarely the problems of preserving it from decay. Thus among 
 the first attempts were the placing of stone blocks under wooden 
 pillars to keep away soil and vegetation. The tops were also 
 capped in this manner and it is thought that these early practices 
 are the origin of the base and capital of our modern stone pillars. 
 The antiseptic value of essential oils was also well understood, 
 these being obtained from the olive tree and from various cedars 
 and junipers growing along the Mediterranean. The practice 
 was to either rub these oils over the surface of the wood to be pre- 
 served, or to bore numerous small holes in the wood and pour oil 
 into them. In this manner the magnificent statue of Jupiter by 
 Phideas and the famous statue of Diana were preserved. Pliny 
 
10 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 asserts that the oils not only retarded decay but kept the wood 
 free from insect attacks. It was common practice among the 
 Romans and hut dwellers of the Baltic to char their timbers 
 which were used for piling before placing them permanently in 
 their structures. This method of preserving wood is used even 
 to the present day. 
 
 It was perhaps the rapid decay of timber in the British warships 
 that gave wood preservation its first great impetus. It is re- 
 ported that 40 acres of oak forest were required to construct a 70- 
 gun ship and that the great prevalence of rot in the vessels as- 
 sumed the proportions of a national calamity.^ M. Paulet in his 
 book entitled, " Conservation des Bois," enumerates 173 proc- 
 esses or methods that were tried, most of which proved unsuccess- 
 ful. About this time Holland was also wrestling with the pres- 
 ervation of the timbers used in the construction of her dykes and 
 marine structures. Later came the development of the steam 
 engine and birth of the locomotive, which brought a new drain on 
 the forest, principally for cross-ties, so that some method of 
 preserving wood became a positive necessity. It was during 
 the first quarter of the 19th century that modern methods of 
 injecting wood may be considered as beginning, although the 
 most successful attempts did not come until a few years later. 
 It is interesting to note that the most efficient preservatives were 
 used several years before patents were taken out on them, or 
 even before their use was commercialized. Thus mercuric 
 chloride was used by Homberg in 1705 and by De Boissieu in 
 1767, although it is with Kyan's name that the salt is best known, 
 he having taken a patent on its use in England in 1832. Even 
 to the present, its use is commonly called "Kyanizing." So it is 
 with copper sulphate, recommended by De Boissieu and Borde- 
 nave in 1767 and best known as "Margaryizing," although 
 Margary's patent was not granted until 1837. Chloride of zinc 
 was recommended by Thomas Wade in 1815 and by Boucherie 
 in 1837 but its use is referred to as "Burnettizing" from the pat- 
 ents of Sir William Burnett in 1838. Franz Moll took out a 
 patent in 1836 for injecting wood in closed iron vessels with oils 
 of coal-tar but the practical introduction is attributed to John 
 Bethell, whose patent is dated 1838 and whose name is now fam- 
 ous in the art of preserving timber. It is reported that Bethell' s 
 
 ^ The Preservation of Timber by the Use of Antiseptics." Samuel B. 
 Boulton, 1885. 
 
INTRODUCTION 11 
 
 process required the timber to be in an air-seasoned condition 
 before the preserving oils were injected. The treatment of green 
 timber with creosote by first using steam followed by a vacuum 
 prior to impregnation with the oil is attributed to Hayford.^ 
 
 The marked success met with by the use of the preservatives 
 mentioned gave a pronounced impetus to the wood-preserving 
 industry throughout Europe. Later, progress was directed more 
 to perfecting the use of these preservatives than in attempting to 
 introduce new ones. Thus it was found that zinc chloride had a 
 tendency to leach from wood, and to overcome this objection as 
 well as give added effectiveness to the treatment, Julius Rutgers 
 introduced in Germany about 1874 a method of treating ties 
 with a mixture of zinc chloride and creosote. This method has 
 met with considerable favor in Germany and is now one of the 
 leading processes in use in that country. The excellent results 
 secured with coal-tar creosote have always caused this pre- 
 servative to be held in very high repute. Its comparatively 
 high cost led Max Reuping to take out a patent in Germany in 
 1'902 on a process of impregnating it into wood, and subsequently 
 withdrawing a part of it so that the total amount of oil actually 
 consumed was greatly reduced. This process named after the 
 inventor, has also met with pronounced success in European 
 countries. Several other methods of treating wood have lately 
 been exploited in Europe but few of them have met with the suc- 
 cess of the Burnettizing and Bethell processes. 
 
 Wood preservation is now practised in all the leading European 
 countries. In England creosoting appears most popular, while 
 in Germany both creosote and zinc chloride are extensively used. 
 The same is true of France, where appreciable quantities of poles 
 are still impregnated with copper sulphate. Not only ties and 
 poles but vast quantities of mine timbers, paving blocks, piles, 
 posts, vineyard sticks and lumber are now annually treated, so 
 that the industry may be considered as permanently established 
 and an engineering necessity. Figures on the amount of wood 
 treated in Europe are not available, but it is reported that about 
 16,000,000 ties are annually preserved and that the total number 
 of plants in operation is about 70. It appears, therefore, that 
 the plants in Europe have on the average a much smaller capacity 
 than those in our country. 
 
 United States. — The commercial application of wood preserva- 
 
 ^ Reprint, Journal of Franklin Institute, 1878. 
 
12 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 tion in our country first became of practical importance in 1848, 
 when a Kyanizing plant was built at Lowell, Mass. A great 
 many tests, however, had been carried on in a more or less 
 primitive way previous to this. For example, Kyanized chestnut 
 ties were laid near Baltimore in 1838 by the Northern Central 
 Railroad. The Lowell plant was built primarily for the treat- 
 ment of timbers used in the locks and canals on the Merrimac 
 River. It operated the Kyanizing process for 2 years, and then 
 substituted the zinc chloride method, but in 1862 the officials, 
 becoming dissatisfied with these treatments, reverted to Kyaniz- 
 ing, and since this date the plant has been in more or less con- 
 tinuous operation. 
 
 In 1856, the Vermont Central Railroad erected a Burnettizing 
 plant for the treatment of bridge timbers and ties, but it was 
 abandoned after being in operation 4 years. About this time 
 the Chicago, Rock Island and Pacific, the Boston and Albany and 
 Erie Railroads built plants for the treatment of timber with zinc 
 chloride. All these plants met with but partial success, princi- 
 pally because of the then abundant supply of timber and the high 
 cost and inexperience in handling treated timbers. Operators 
 could not accustom themselves to the delay which timber treat- 
 ments entailed; consequently few plants treated their timber for 
 a sufficient period to enable it to be properly impregnated with 
 the preservative. In 1863 the Philadelphia, Washington and 
 Baltimore Railroad, and in 1867 the Philadelphia and Reading 
 Railroad built Burnettizing timber-treating plants, but both had 
 a short life due to the unsatisfactory results secured. In 1865, 
 the Old Colony Railroad erected a plant at Somerset, Mass., for 
 the treatment of bridge timbers with creosote. This, apparently, 
 represents the first practical attempt to use this material in the 
 United States. The work was done with a rush and in a careless 
 manner, much of the timber being trimmed after it was treated. 
 In spite of this, the work was considered a success. 
 
 In 1867, Professor Seeley of New York obtained a patent for 
 treating timber without the use of pressure. He erected treat- 
 ing plants in New York, Chicago, and at the St. Clair Flats in 
 Michigan. His claim was that green timber could be treated 
 just as effectively as seasoned timber. This, however, accounts 
 in a large measure for Seeley's failure. His process was neverthe- 
 less adopted by the Government for its work at the St. Clair Flats 
 in the construction of dikes, etc., along its canal, and by the 
 
INTRODUCTION 13 
 
 Chicago, Rock Island and Pacific and the Chicago, Burlington 
 and Quincy Railroads. At the World's Fair in St. Louis in 1904, 
 von Schrenk revived this "open tank" process, and its use was 
 later on made the subject of careful study by the U. S. Forest 
 Service, until there are now several plants in operation in this 
 country. 
 
 About the time Seeley's process was being promoted, Mr. L. S. 
 Robbins introduced a method in which he impregnated timbers 
 with vapors of creosote. This process was extensively adver- 
 tised and local companies were formed in New York, New Jersey, 
 Pennsylvania, Massachusetts, Connecticut, and California with 
 large capital. It failed, however, in practically all cases, espe- 
 cially where it was used in marine construction. Mr. C. B. Sears, 
 engineer in charge of the government works in California, states 
 "that it failed absolutely to protect the timber from the Teredo, 
 which was not more than 2 months longer in attacking it than 
 the untreated timber, and when once in, its action seemed to 
 be more rapid." 
 
 About 1870 Mr. Thilmany treated a great many ties with 
 copper sulphate and barium chloride for the Wabash, Pennsyl- 
 vania and Ohio, Lake Shore and Michigan Southern, Cleveland 
 and Pittsburg, and Baltimore and Ohio railroads, but the process 
 met with the fate of most of its predecessors and it was eventually 
 abandoned. 
 
 In 1872, it is reported, Mr. George H. Fletcher boiled some 
 paving blocks in dead oil of coal-tar and laid them in the yard of 
 the New Orleans Gas Light Company. They absorbed about 20 
 pounds of oil per cubic foot and when inspected 30 years after- 
 ward were thoroughly sound. 
 
 Modem timber processes may be considered as beginning in 
 this country in 1875, when a creosote plant was erected at West 
 Pascagoula, Miss., for the treatment of timbers used by the Louis- 
 ville and Nashville Railroad. This plant is still in operation and 
 has met with marked success in its work. In 1878 Eppinger and 
 Russell operated their creosote plant in Long Island City, N. Y. 
 In 1879 the New Orleans and North Eastern Railroad built 
 a similar plant primarily to treat the timbers used in the bridge 
 across Lake Ponchartrain. From this period on the wood- 
 preserving industry has permanently grown, the Wyckoff Pipe 
 and Creosoting Company erecting a plant in 1881, the Colman 
 Creosoting Company in 1884, the Santa Fe Railway Company in 
 
14 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 1885, the Chicago Tie Preserving Company in 1886, etc., until 
 at the present time there are now about 90 plants in operation 
 scattered all over the United States and treating annually over 
 125,000,000 cu. ft. of wood; (For complete list see Appendix.) 
 
 It is interesting to note that the first successful attempts in 
 timber preservation in this country were not made on account of 
 scarcity of timber, but because of the high cost of replacing it after 
 it had deteriorated. For example, the timber-treating plant 
 built by the'New Orleans and North Eastern Railroad was erected 
 to treat the timbers used in constructing the Lake Ponchartrain 
 bridge, as these, without treatment, would not last more than 
 3 or 4 years due to rapid decay and attack by borers. 
 Although treated in 1875, many of these timbers are still sound 
 and in service. Some method of preserving the wood was there- 
 fore an absolute necessity to the railroad company in order to 
 maintain this bridge. Similar conditions prevailed in other 
 places along the Atlantic Coast and in mines, but the gradual 
 depletion of our forests and rise in the value of lumber has- given 
 a further impetus to the growth of the industry so that there are 
 now but few places in the United States where wood preservation 
 will not pay. 
 
CHAPTER II 
 
 FACTORS WHICH CAUSE THE DETERIORATION OF 
 STRUCTURAL TIMBER 
 
 Discussion of Their Relative Importance. — Timber placed in 
 service is subject to deterioration from many causes, and its 
 strength eventually becomes so weakened that it must be re- 
 moved and replaced with sound timber or some other material. 
 The chief factors which cause such deterioration are decay, 
 insects, marine borers, mechanical abrasion, and fire. Others of 
 less extent are alkaUne soils, birds, and sand storms. Our 
 country is so vast and its development has been so rapid, that it 
 is absolutely impossible at this time to even estimate with any 
 degree of accuracy the relative importance of the above factors 
 responsible for the deterioration of structural timbers. In the 
 absence of statistics, it seems very probable, however, that decay 
 is by far the most important, as enormous quantities of wood rot 
 annually. Next in rank to decay, perhaps, comes mechanical 
 destruction, such as the railcutting of ties; then in gradually de- 
 creasing amounts, fire, insects, and marine borers. We will dis- 
 cuss in this chapter the manner in which these destructive agents 
 work, as it will aid in understanding the protective measures 
 taken to overcome them. 
 
 Decay. — On this subject voFumes have been written, and it 
 seems strange that even at the present time the cause of decay 
 is a matter little understood by many timber treating engineers.^ 
 For this reason it is felt desirable to review the more essential 
 facts that are known in the hope that they may clearly fix the 
 basic principles of fungous growth. The prevailing theory about 
 1840 as to the cause for decay in timber was molded by the 
 opinion of the great chemist Liebig. Liebig taught that the proc- 
 ess of fermentation in certain fluids and the putrefying or decay 
 of organized bodies, animal and vegetable, were caused by a 
 species of slow combustion to which he applied the term "erema- 
 causis;" that it required for its ordinary development the pres- 
 
 ' See Proceedings American Wood Preservers' Association, 1912. 
 
 15 
 
16 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 ence of moisture and atmospheric air; that its action was pro- 
 voked by oxygen and its method of action was by a communica- 
 tion of motion by the atoms of the affected ferment to the atoms 
 of the body affected. He denied that fermentation, putrefaction, 
 and decomposition were caused by fungi, parasites or infusoria, 
 although these organisms might sometimes be present during 
 the process. 1 
 
 With the introduction of the microscope and the consequent 
 intensive study on the minute forms of life, the theory of Liebig 
 gradually became shattered. The bodies of mammoths pre- 
 served in ice through countless ages, the fragments of wooden 
 piles which have endured undecayed for centuries when driven 
 deeply below the surface of water, all confirm the experiments of 
 Pasteur and Tyndall and prove the exclusion of germs prevents 
 decay. Specimens are on exhibition of a sound wooden pile 
 known as the remains of a bridge (destroyed by fire) which was 
 constructed by Charlemagne across the Rhine; of pieces of piles 
 in the foundation of the bridge across the Medway at Rochester, 
 which was destroyed by Simon de Montfort in 1264. Thousands 
 of exact laboratory tests have established beyond all peradven- 
 ture, that the true cause of decay in timber are low forms of 
 plants called fungi and bacteria. The action of bacteria in de- 
 caying wood is not clearly known even to this day, but there is 
 little reason to doubt but what the same methods used in com- 
 bating fungi will prove equally as effective in combating them. 
 
 Only a comparatively small percentage of fungi and bacteria 
 have the ability to decay wood and a great many will not even 
 grow on wood. Of those which do grow on wood it is customary 
 to divide them, in a discussion of this kind, into "harmful" or 
 wood destroying and "harmless" or saprophytic fungi. All 
 fungi are forms of plants which are parasitic, that is, they are 
 dependent on other plants for their existence. They all lack 
 "chlorophyll," a substance which gives plants their green color 
 and which is instrumental in taking the gases from the air and 
 transforming them into plant substance. 
 
 Fungi reproduce in two ways, (1) sexually, by means of minute 
 "spores" which can be likened to tiny seeds, and (2) asexually, 
 by means of "mycelia" which can be likened to minute roots. 
 The spores are blown about by the wind like very fine particles 
 
 ' ,1 S. B. Boulton, The Preservation of Timber by the Use of Antisep- 
 tics, 1885. 
 
DETERIORATION OF STRUCTURAL TIMBER 17 
 
 of dust, and when they alight on wood, start to germinate and 
 send their fine mycelia into the wood gradually decaying it. 
 If these mycelia come in contact with sound wood, as for example, 
 when a piece of decayed wood touches a piece of sound wood, they 
 grow into the sound wood and will ultimately decay it. In this 
 way, decay is also spread. Some fungi have the ability to send 
 their mycelia over materials which they will not attack, in their 
 search for wood. Thus if two pieces are separated a foot or 
 more apart, the mycelia from the decayed piece may reach out 
 over this space and attack the sound piece. This characteristic 
 is common in the so-called "house fungus." By the secretion 
 of little understood chemicals by these mycelia, the wood fiber 
 is dissolved and its substance serves as food for the fungus. 
 These cheniicals are termed "enzymes" or "ferments." Since 
 fungi vary greatly in their capacity to secrete ferments, we have 
 the key to jtheir widely varying action upon timber. It is only 
 those fungi which attack cellulose and lignin vigorously that 
 effect the durability of timber to any serious degree. Give them 
 a favorable temperature and proper moisture and air supply and 
 the destruction proceeds rapidly. 
 
 Fungi may be classified in regard to the form and habit of 
 growth of the "mushrooms" technically called "fruiting bodies." 
 Based on these characters, the "harmful" or wood destroying 
 fungi may be divided into three classes : 
 
 1. Fleshy forms of the "mushroom" types which have a dis- 
 tinct stem, a more or less circular cap with plates or "gills" on 
 the under side. This class contains few destructive forms. (See 
 Plate I, Fig. C.) 
 
 2. Fungi which are tough, corky or woody and which have no 
 stem, but are attached to the wood by the side of their rough 
 semicircular caps. (See Plate I, Fig. D.) The under surface is 
 provided with pores of various outlines, circular, angular, or 
 sinuous. Frequently the caps grow in clusters, one above the 
 other. This class contains many destructive kinds. 
 
 3. Fungi similar to those in class (2), but whose under surface 
 is smooth and not differentiated with pores or plates. (See plate 
 II, Fig. a.) 
 
 The "harmless" fungi are comparatively few. There are 
 several species similar to those described in class (1) which grow 
 on wood after it has reached an advanced stage of decay. Another 
 form (Schizophyllum commune) having a wide distribution is 
 
 2 
 
18 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 small, white, thin, leathery, and flexible, and has a bracket-like 
 appearance. It frequently occurs on sound oak or pine and lives 
 mostly on the sugars and starches in the wood. Other fungi 
 which are white, green, brown or black and commonly called 
 "molds" also belong to the "harmless" group. They produce 
 the stain in wood but do not injure its strength to any appreciable 
 extent.^ 
 
 Insects. — The deterioration of timber through insect attack 
 is greatly underestimated in this country. This matter has 
 been made the subject of a special investigation by the U. S. 
 Bureau of Entomology and it is estimated that the annual loss 
 from this cause amounts to $100,000,000.^ Round timber with 
 the bark on, such as poles, posts, mine props, saw logs, etc., 
 is particularly subject to attack by round-headed borers, timber 
 worms, and ambrosia beetles. Frequently the insects continue 
 the work in the unseasoned and even dry lumber cut from logs 
 which had been previously infested. Their prolonged activities 
 in mine timbers is well known; also in cabins, and rustic furniture. 
 Hickory hoops and poles are often rendered worthless by borers 
 and beetles. Stave and shingle bolts, handle or wagon stock, and 
 pulpwood are peculiarly subject to attack. Although termites 
 are not usually associated with the destruction of timber in this 
 country, nevertheless they cause considerable damage to poles 
 and construction timbers used in buildings, sometimes completely 
 destroying them. Many of the insects not only feed on the wood 
 but burrow into it for their protection or breeding grounds. This, 
 of course, weakens the wood and allows channels through which 
 water and the spores of destructive fungi can enter. Each 
 specie of insect has its own peculiar method of attackso that it is 
 not possible in a treatise of this kind to describe all of them. Two 
 rather typical examples will, however, be given: The "powder- 
 post insect" which bores into dry wood and the "pole borer" 
 which attacks poles and similar products. 
 
 The Powder-post Insects.' — "The adults or winged forms of this class 
 of insects are small, slender or stout, brownish to nearly black beetles, 
 
 ' For a scientific discussion of the destruction of wood by fungi and bac- 
 teria, the reader is referred to Bulletin 266 of the U. S. Bureau of Plant In- 
 dustry, by McBeth and Scales. 
 
 2 Circular 129, U. S. Bureau of Entomology, A. D. Hopkins, 1910. 
 
 ' Circular 55, U. S. Division of Entomology, by A. D. Hopkins. 
 
Plate II 
 
 Fig. a. — A red-oak tie attacked by a wood destroying fungus (stereum fas- 
 ciatum, Schw.)- (Photo through courtesy of C. J. Humphrey.) 
 
 Fig. B. — (l)The pole borer, male and female beetles. (2) Young larvae. 
 (Circular 134, U. S. Bur. Entomology.) 
 
 (Facing ■page 18) 
 
Plate II 
 
 Fig. C. — Gallery of the pole borer. Fig. D. — Mines of the pole 
 
 borer near the surface of the 
 ground. 
 Work of the pole borer (parandra brumiea Fab.) in an untreated chestnut 
 pole. (Circular 134, U. S. Bur. of Entomology.) 
 
DETERIORATION OF STRUCTURAL TIMBER 19 
 
 which upon emerging from the wood where they breed and pass thp win- 
 ter, fly or crawl about in search of suitable wood material in which to 
 deposit their eggs. 
 
 The different species vary in their habits and life history, from the egg 
 to the adult, but in general that of the true powder-post beetles is as 
 follows : The winter is passed in the wood. The eggs are deposited under 
 normal conditions soon after activity commences in the spring, while 
 in storehouses and buildings kept warm and dry they may continue their 
 activity through the year and deposit eggs much earlier. The minute 
 white "worm" or grub (the second stage of the insect known as the 
 larva), upon hatching from the egg, proceeds to burrow in and through 
 the wood in all directions, feeding and growing as it proceeds, until it has 
 attained its full growth. It then excavates a cell at the end of its burrow, 
 in which it transforms to a semidormant stage (the pupa, or third stage 
 in the insect's life), remaining thus until the legs and wings have fully 
 developed, when it bores its way out and appears as the matured adult or 
 beetle (the fourth stage), to mate and repeat the hfe process. Under 
 normal conditions, so far as is positively known, there is probably only 
 one generation annually. 
 
 Each female deposits many eggs, and many females oviposit on or in a 
 single piece of wood, so that the combined work of their numerous pro- 
 geny, borrowing through the wood in quest of food for their development, 
 results in the complete destruction of the interior wood fiber and its con- 
 version into a mass of fine powder. If the first attack and the first 
 generation do not accomplish this destruction, subsequent generations 
 wiU follow in the same wood until nothing of the solid fiber is left but a 
 thin outer shell." 
 
 The Pole Borer.' — This insect (Parandra brunnea Fab.), is an 
 elongated, creamy-white, wrinkled, round-headed grub or larva. 
 (See Plate II, Fig. B-2.) It hatches from an egg deposited by an 
 elongate, mahogany-brown, shiny, flattened, winged beetle, from 
 two-fifths to four-fifths of an inch inlength. (See Plate II, Fig. B-1.) 
 It appears that the eggs are deposited from August to October in the 
 outer layers of the wood of the pole near the surface of the ground. 
 The young borers, upon hatching, excavate shallow galleries in 
 the sapwood, then enter the heartwood, the mines being gradually 
 enlarged as they develop. As they proceed they closely pack 
 the fine boring dust behind them. This peculiar semidigested 
 boring dust, which is characteristic of their work, is reddish to 
 dunnish yellow in color and has a clay-like consistency. The 
 burrows eventually end in a broad chamber, the entrance to which 
 
 1 Circular 134, U. S. Bureau of Entomology, by T. E. Snyder. 
 
20 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 is plugged with excelsior-like fibers of wood. Here is formed the 
 resting stage, or pupa, which transforms to the adult beetle. 
 Often all stages, from very young grubs only about one-fourth 
 inch long to full-grown grubs over 1 inch long, pupae, and adults 
 in all stages to maturity are present in the same pole. Adults 
 have been found flying from July to September. 
 
 The insect attacks poles that are perfectly sound, but will work 
 where the wood is decayed; it will not, however, work in wood that 
 is "sobby" Cwet rot), or in very "doty" (punky) wood. It 
 has not yet been determined just how soon the borers enter the 
 poles after they have been set in the ground. However, poles 
 that had been standing only 4 or 5 years contained larvae and 
 adults of this borer in the heartwood, and poles that had been 
 set in the ground for only 2 years contained young larvae in 
 the outer layers of the wood. 
 
 The presence of the borers in injurious numbers can be de- 
 termined only by removing the earth from about the base of the 
 pole; the large holes made when the adults come out are found 
 near the line of contact with the soil. Often large, coarse borings 
 of wood fiber project from these exit holes. Sometimes the old 
 dead parent adults are found on the exterior of the poles under- 
 ground. During August the young adults may be found in 
 shallow depressions on the exterior of poles below the ground 
 surface. 
 
 Marine Borers. — In many places along both the Atlantic and 
 Pacific coasts timber used for piles in wharfs and other marine 
 structures is attacked by marine wood borers. There are many 
 kinds of such borers but those which occur in our waters can be 
 classed into three genera of moUusks, Xylotrya, Nausitoria, and 
 Teredo, commonly known as "ship worms," and three of crus- 
 taceans, Limnoria, Chelura, and Sphaeroma, commonly called 
 "wood lice." 
 
 The activities of the shipworms were known to the ancient 
 Romans, who sheathed their ships against them. Clement 
 Adams in the reign of Henry VI notes that upon the squadron 
 sent out to discover the Northeast Passage — "they cover a piece 
 of the keels of the shippe with their sheets of leade, for they had 
 heard that in certaine partes of the ocean a kinde of wormes is 
 bredde, which many times pearceth and eateth through the 
 strongest oake that is."i 
 
 1 "Voyages and Travels" Vol. II, C. R. Beazley. 
 
DETERIORATION OF STRUCTURAL TIMBER 21 
 
 • 
 
 Xylotiya, Nausitoria, and Teredo' in structure and mode of 
 life are very much alike. Hence for all practical purposes a 
 description of the work of Xylotrya will be suflBicient (see Fig. 
 1). The average diameter of an egg ,is less than 1/500 inch, and 
 a single worm may lay 100 million in a season. When the egg 
 hatches, the embryo swims around for about a month and the 
 exposed surface of the wood is then attacked by countless thou- 
 sands of them which immediately begin to bore. The hole by 
 which it enters is minute, but beneath the surface the burrow is 
 soon enlarged to accommodate the rapidly growing body. The 
 burrow extends usually in a longitudinal direction and follows 
 a very irregular, tangled course. 
 
 There is some controversy as to the method by which boring 
 is accomplished. It is possible that the body is held rigidly by 
 
 ■Xylotrya or ship worm. 
 
 an extensile sucker-like foot, ordinarily incased within the two 
 shell valves (Fig. 1, a), and that the two valves revolve around 
 this, cutting the wood away with fine, hard; tooth-like protuber- 
 ances. It is possible on the other hand that the muscular ring 
 near the posterior end of the body (Fig. 1, b) is pressed firmly 
 against the walls of the burrow, and that the whole body, including 
 the shell valves and foot, revolves slightly in both directions, the 
 shell valves doing the cutting. It is probable, however, that the 
 boring is done by a united action of the valves and foot. The 
 posterior muscular end is probably the only portion of the body 
 held rigid. The valves revolve slightly, cutting into the wood, 
 partially in front and partially on the sides. At the same time 
 
 ' Circular 128, U. S. Forest Service, "Preservation of Piling against Mar- 
 ine Borers," by C. S. Smith, 1908. 
 
22 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 • 
 
 the foot, either by the secretion of an acid substance, or of 
 spicules used as a grinding medium, assists in breaking down the 
 wood fibers directly in front of the advancing mollusk. The 
 hardest knots are penetrated with ease, but the softer parts of the 
 wood are preferred. As the body grows it secretes a calcareous 
 substance to form a hard lining around the burrow. This is 
 thicker in soft, porous woods than in those which are hard and 
 dense. 
 
 At the posterior end of the body, just below the muscular ring, 
 are two siphons, or tubes (Fig. 1, c). Through the shorter one 
 the fine borings are ejected with the excreta; through the longer 
 one water and food are taken in. The food consists wholly of 
 infusoria, and is not obtained from the wood itself. The sole 
 object of boring into the wood is to secure a place of shelter. 
 
 Xylotrya rapidly attains maturity. High temperatures pro- 
 mote quick work and hasten bodily development. The size 
 attained by the adult depends upon the species, the locality, and 
 the obstacles to excavation. In rare cases a length of 6 feet, with 
 a diameter of over 1 inch, is said to be attained. Other species 
 seldom attain a length of over 5 inches or a diameter of over 
 1/4 inch. 
 
 The portion of the pile commonly attacked is that between 
 mean tide-water mark and a point about 4 feet below low water, 
 though sometimes it extends downward as far as the pressure 
 of the water will permit. The entrance holes do not indicate the 
 extent of attack, as the entrance may be at mean tide-water 
 mark and the active boring head several feet above. On the 
 other hand, part of the excavation may be below the mud line, 
 though the entrance is never so situated. More than half of the 
 weight of the structure may be removed without any visible signs 
 of deterioration upon the surface. When the worm is dead, the 
 minute entrance holes often become filled with mud or debris, 
 so that it is impossible to discover the true condition of the pile 
 without chopping into it. 
 
 The Phola is primarily a marine stone borer but certain species 
 will attack wood. In form it resembles a long clam. In boring 
 it braces its open shell against the sides of its excavation, while its 
 long sucking foot emerges and rubs the surface of the stone or 
 wood. Particles of sand are operated between the foot and the 
 stone or wood, thus grinding the excavation. Granite, marble, 
 or any kind of stone seems to be attacked. Fortunately, its 
 
DETERIORATION OF STRUCTURAL TIMBER 23 
 
 ravages on wood are not as extensive as the Xylotrya and 
 Teredo. 
 
 Undoubtedly all shipworms thrive best under the influence of 
 heat, though some can endure a relatively low temperature. 
 Certain species have been reported from as far north as Eastport, 
 Me. Since warm water increases their activity and permits 
 them to continue their attacks throughout the greater portion 
 of the year, shipworms are most destructive from Chesapeake 
 Bay south to Florida, on the Gulf of Mexico, and along the entire 
 Pacific coast. 
 
 The shipworm may be present in some waters, yet absent in 
 others near by. This is usually due to a difference in the water. 
 Xylotrya appears to be able to endure the brackish water of the 
 inner New York Harbor, while Teredo cannot live there, though 
 it is present in the ocean just outside. The shipworrri is very 
 active on the north Pacific Coast, yet it is absent about the mouth 
 of the Columbia River, where the amount of salt in the ocean is 
 influenced by the inflow of fresh water. The effect of water 
 conditions was also noticed in Holland during certain years in 
 which the worms were unusually destructive. Little rain fell 
 during those years, and the small amount of river water brought 
 to the coast was thought to have allowed the ocean to become 
 more saline about the mouths of these streams. Analyses show 
 that there is a variation in the proportion of salt present in the 
 waters of the coast during the dry and the rainy seasons. 
 
 Observations along Chesapeake Bay and the Gulf of Mexico 
 indicate the species found there will thrive in waters with a saline 
 density indicated by a specific gravity of from 1.0054 to absolute 
 saturation, 1.0333; that they thrive in temperatures of from 
 55° F. to the highest found along our coasts; that they work in 
 absolutely clear and in very turbid water; that they seldom work 
 to a depth of over 30 feet; and that the worst attack is usually in 
 the very salty, warm, clear waters. 
 
 The length of time required to destroy an average, barked un- 
 protected pine pile in different localities is shown in the following 
 table: 
 
 From this table it will be seen that the average life of an un- 
 treated pine pile on the Atlantic coast south from Chesapeake 
 Bay and along the entire Pacific coast is but from 1 to 3 
 years. 
 
24 
 
 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 Locality 
 
 Length of life reported 
 
 Average 
 
 Minimum 
 
 Colon, Panama 
 
 Norfolk, Va ' 
 
 Newport News, Va 
 
 Hampton Roads 
 
 St Andrews, Fla 
 
 Pensacola, Fla 
 
 Fort Morgan, Ala. . . . 
 
 9 months-1 year 
 
 
 1 year 
 
 
 11/2 vears 
 
 
 
 
 2-3 years 
 
 1 year 
 1 year 
 1 year 
 29 days 
 5 months 
 3 months 
 
 West Pascagoula, Miss 
 
 Texas City, Tex 
 
 Galveston, Tex 
 
 Aransas Pass, Tex 
 
 Puget Sound 
 
 Klawak, Alaska 
 
 2-3 years 
 
 1 year 
 
 1 1/2 years 
 
 1 year 
 
 
 3 years 
 
 18-20 months 
 
 Of the crustacean borers, Limnoria, or the "wood louse," is 
 the only one of great importance (Fig. 2). It is gregarious in its 
 habits, and is about the size of a grain of rice. The wood in 
 which it tunnels furnishes both food and shel- 
 ter. Boring is done with very sharp man- 
 dibles. The little galleries excavated are about 
 1/2 inch long and only slightly larger in dia- 
 meter than the borer. The galleries extend 
 inward radially, side by side, in countless 
 numbers, so that the wood partitions between 
 them are very thin and are soon destroyed by 
 wave action, thus exposing a fresh wood sur- 
 face to attack. Boring is carried on at the 
 rate of about 1/2 inch per year. Soft and 
 hard woods are both destroyed, but soft woods 
 much more quickly. If possible, knots, dense 
 summerwood, and other obstructions are 
 avoided. The attack is usually centered upon 
 a limited zone above and below low-water 
 mark. Hence where the tide is great the 
 surface exposed to attack is large. 
 Limnoria is reported by the U. S. Fish Commission as occurring 
 rarely at a depth of 40 feet. It has a wider temperature range 
 than Xylotrya, but requires pure salt water and cannot exist 
 in dirty or fresh water. It is found along the Atlantic 
 coast from Florida to Nova Scotia. It occurs sparingly in Long 
 Island Sound, is quite abundant along the coast of Massachusetts 
 
 Fig. 2. — ^Limnoria. 
 
DETERIORATION OF STRUCTURAL TIMBER 25 
 
 and in the Bay of Fundy, It also does great damage along the 
 whole Gulf of Mexico, on the north Pacific coast around Puget 
 Sound, and in the Straits of San Juan de Fuca. 
 
 All the woods commonly used for piling are subject to the at- 
 tacks of marine borers. Some doubt has been expressed whether 
 borers attack certain species which are not indigenous to this 
 country and some native woods that have an extremely porous 
 structure. Examples of the first class are certain eucalypts, and 
 of the second class, palms and palmettos. From investigation it 
 is clear that species of the first class are not immune from attack, 
 and that those of the second, although practically immune, are 
 found in such small quantities and are so lacking in the require- 
 ments of structural timbers that the fact is not important. Hard- 
 ness is no barrier to attack, although boring is probably slow in 
 dense woods like ebony, eucalyptus, etc. Whenever partial or 
 complete immunity is reported, it is perhaps largely due to local 
 conditions rather than to the kind of wood. 
 
 Mechanical Abrasion. — Wood placed in service is often de- 
 stroyed solely from mechanical causes, and when these cannot be 
 mitigated or eliminated, the protection of such wood from decay 
 is frequently inadvisable. Of the various forms of structural 
 timbers, cross- ties are most subject to serious mechanical wear, 
 and the loss from this cause is estimated at 15 /percent of the total 
 number of ties annually destroyed. Wood paving blocks, piling, 
 and planking used in piers, timbers in cars, and all forms of 
 vehicles, mine props, etc., are subject to mechanical deterioration. 
 In many cases no protection can be afforded the timber from such 
 loss, as, for example, occurs in mine props subject to "squeeze." 
 It frequently happens, however, that the wood can be protected 
 by coating its surface with some hard substance such as iron on 
 those portions where the abrasion occurs. At times, protection is 
 afforded by coating the permanent timbers with timbers that are 
 only temporary and whose function it is to absorb shock and stand 
 all wear. 
 
 Fire. — The action of intense heat on wood is so well understood 
 that little or no comment is necessary. Combustion, of course, 
 occurs, the wood being decomposed into carbon dioxide, water 
 vapor, and ash, so that its original properties are completely 
 changed. Wood which is wet or is in a green condition is much 
 more difficult to ignite than wood which is dry, because it can 
 absorb considerably more heat units in converting the water it 
 
26 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 contains into steam. Consequently, wood containing high 
 percentages of water is less liable to injury from fire than wood 
 which is dry. Most structural timbers, however, particularly 
 those used in buildings where they are protected from the 
 weather, are sufficiently dry so that they can easily be ignited. 
 The fire losses in the United States are enormous, reaching a sum 
 estimated at $215,000,000 a year. Of course, the value of the 
 timber actually destroyed is but a small percentage of this 
 amount, most of it being for labor of construction and for other 
 materials and products. There is no doubt but what this loss can 
 be very materially reduced, as is shown by conditions abroad, but 
 to secure most successful results it is felt that the building itself 
 should not only be fire-retardant but that as many of its contents 
 as possible should also be made to resist the flames, and the general 
 public educated to exercise caution. 
 
 Minor Factors. — Inaddition to the factors just discussed, there 
 are a number of others of minor importance which destroy or 
 injure wood. The chief of these are alkaline soils, birds, sapstain 
 and sand storms. 
 
 Alkaline Soils. — In many portions of the United States, par- 
 ticularly in the West, vast areas of soil are more or less alkaline." 
 Generally speaking, two kinds of alkaline soils are recognized, 
 "black" and "white" alkali. Black alkali is sodium carbonate 
 while the white is sodium sulphate and other sodium salts. It 
 has been repeatedly claimed that wood in contact with such soil 
 will be rapidly attacked and soon become worthless. Pieces of 
 wood flumes, poles, and ties have been received that were claimed 
 to have been destroyed by the soil. In all cases examined the 
 specimens showed the presence of wood-destroying fungi. For 
 example: Mr. A. O. Campbell, Assistant Engineer of the Oregon 
 Short Line Railroad Company, submitted for analysis in 1908 
 several samples of ties, ballast, and soil which he took from a 
 portion of the line known as the Lucin Cutt-off between Ogden 
 and Lucin, Utah. These ties had completely deteriorated in 
 about 8 years. A chemical analysis showed the water- 
 soluble materials washed from the ballast and soil in which the 
 ties were placed contained about 6 percent of sodium carbon- 
 ate. A microscopic examination of the wood, however, showed 
 it to be full of fungus mycelia. It is thought that the amount 
 of alkali in most alkaline soils is too small to seriously affect the 
 strength of wood in contact with it, but that under certain condi- 
 
Plate III 
 
 Pjq a— Cedar ties badly damaged by rail .cutting. Upper section 
 shows tie without plate, lower section shows tie plate was too small, {i! orest 
 Service photo.) , 
 
 ' (Facing page 26.) 
 
Plate III 
 
 Fig. B. — Poles destroyed by a sleet storm in Maryland, 1904. (Forest 
 
 Service photo.) 
 
 Fig. C. — Results of a fire at the Arlington Manufacturing Company's 
 Mm, Arlington, N. J. In rebuilding, wood beams were used throughout. 
 (Photo courtesy of the Boston Mfg. Mutual Fire Ins. Co.) 
 
DETERIORATION OF STRUCTURAL TIMBER 27 
 
 tions of warm temperature and abundant moisture, chemical 
 action between the alkali and the wood might occur and deteriora- 
 tion result in time. As the chemical action of these alkalies 
 upon wood even under the most favorable conditions is but slight, 
 as is indicated by tests to reduce wood to pulp, most of the trouble 
 that has been experienced can be attributed to decay. 
 
 Birds. — Woodpeckers are the only birds which are charged 
 with the destruction of structural timber. Telephone and 
 telegraph poles seem to be the chief forms attacked, although 
 at times they will drill holes into dwellings. In 1906, the 
 author made a count in Louisiana of a number of telegraph poles 
 attacked by woodpeckers.* Out of 268 poles, 110 or 41 percent 
 had been bored into. In southern Indiana another examination 
 was made of two pole hnes near Greenwood. In one, which 
 extended" north, 21 percent of 89 poles examined had been 
 attacked, and in the other, which ran south, out of 58 poles only 
 59 percent were uninjured. 
 
 The woodpeckers which are most injurious are the ant-eating 
 woodpecker (Melauerpes formicivorous) , the gold-fronted wood- 
 pecker (Centurus aurifrous), and the red-headed woodpecker 
 {Melauerpes authrocephalus) , this latter species being the one 
 common in our northern states. The poles are attacked by the 
 birds chiefly for the insects contained in them or for nesting sites. 
 In some cases, however, particularly with the ant-eating wood- 
 pecker, they are used as a storehouse for food. These birds will 
 frequently fly for miles with an acorn in their bill, drill a hole in a 
 pole, and insert the acorn in it, to be used later for food. 
 
 Woodpeckers usually attack a pole near its top, although at 
 times they may bore within a few feet of the ground. Some 
 observations made on a telegraph line paralleling a railroad in 
 Tennessee showed that those poles which were imbedded in hill 
 tops above the level of the track were the ones most seriously 
 attacked, while those which were in the valleys so that their 
 tops were not higher than- the level of the track were seldom at- 
 tacked. The number of holes in a pole may vary from one to a 
 dozen or more, although these larger numbers are not common. 
 The size of the hole varies from about 1/2 inch to 3 
 inches in diameter. When used for nesting sites, the birds may 
 
 1 Some observations on the attack of poles by woodpeckers. — H. F. Weiss, 
 Engineering News, January, 1911. 
 
28 
 
 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 hollow out a pocket 6 or 10 inches in diameter and a foot or more 
 in depth. 
 
 The question of interest to telephone engineers is to just what 
 extent such poles are weakened. It has been found from measure- 
 ments that a 30-foot northern white cedar pole tapers approxi- 
 mately as follows: 
 
 Circumference (inches) 
 43. 
 
 Distance from butt (feet) 
 
 
 37 
 
 5 
 
 36 
 
 6 
 
 34 
 
 10 
 
 32 
 
 15 
 
 29 
 
 20 
 
 27. 
 
 .25 
 
 24 
 
 30 
 
 Assuming the pole a cantilever beam loaded at one end, it is 
 found that it may be hollowed to the extent shown in Fig. 3 
 
 without decreasing its strength. For 
 example, at 10 feet from the ground if 
 only 2 inches of the outer shell are 
 left, the pole will be approximately as 
 strong as though it were solid. If, 
 however, the attack is less than 4 feet 
 from the ground, the pole will be 
 weakened. This illustration neglects 
 the damage done by the entrance into 
 the pole or the subsequent decay which 
 may follow, and assumes that the bird 
 builds its nest exactly in the center. 
 On the other hand, it assumes that 
 the pole has a uniform moisture con- 
 tent throughout its length and that 
 the outer fibers of wood at the ground 
 line are sound. 
 Fig. 3.— Diagram show- "^^^ American Telephone and Tele- 
 ing the extent to which a graph Company made a few tests in 
 pole can be hollowed with- -,nno ry •n /~>i_- . i . 
 
 out impairing its strength. 19^8 near ZanesviUe, Ohio, to deter- 
 mine the effect of woodpecker attacks 
 on the strength of poles. These tests were made by fastening 
 a rope around the top of the pole and pulling with a block and 
 tackle to which a dynamometer was attached. In nine out of 
 
 12 3 4 5 
 
 Radius of P.ole, Inches 
 
DETERIORATION OF STRUCTURAL TIMBER 
 
 29 
 
 twelve cases the poles broke at the ground line and not at the 
 points attacked by the birds. It appears, therefore, that the 
 destruction of poles by birds is but very slight and, considering 
 the good which they do in destroying insects, is no justifica- 
 tion for killing them. 
 
 Sap Stain. — When freshly cut sap lumber is piled in the open air 
 to season it frequently becomes discolored in a few days. This 
 discoloration is not due to weathering but to the growth of certain 
 fungi which live upon the materials in the sapwood cells. Wood 
 thus attacked is considered defective and its value is frequently 
 reduced from 50 cents to $2 per 1000 feet board measure. Perhaps 
 one-fourth of the annual mill cut of the United States is attacked, 
 the most severe damage being in the South. Any locality where 
 warm damp air surrounds the lumber is favorable to the produc- 
 tion of stain. Estimates for the whole country place the annual 
 loss from sap stain at about eight million dollars. 
 
 It is commonly held that lumber attacked by stain is decayed 
 and hence reduced in strength. This decay apparently is very 
 slight, because the fungi which produce the stain do not attack 
 the wood substance to any appreciable extent but rather live 
 upon the materials stored in the cells of the wood. Carefully 
 conducted tests on stained and unstained wood were made by 
 the Forest- Products Laboratory at Madison, Wis., the results 
 of which are shown in Table 2. 
 
 Table 2. — Summary of Tests Showing the Strength of Saj>-stained 
 
 Wood'. 
 
 Species 
 
 Mois- 
 ture per- 
 cent at 
 time of 
 
 test 
 
 Condition 
 
 Strengtli in static bending | 
 
 F.S. at 
 
 EL. 
 (pounds 
 
 per 
 square 
 inch) 
 
 M. of R. 
 
 (pounds 
 
 per 
 
 square 
 
 incli) 
 
 M. of E. 
 
 (1000 
 pounds 
 
 per 
 square 
 
 incli) 
 
 Res. to 
 M.L. 
 
 (pounds 
 
 per 
 
 cubic 
 
 inch) 
 
 Hard- 
 ness 
 total 
 load 
 
 pounds 
 
 Shortleaf pine. . . 
 Longleaf pine 
 
 17.7 
 9.5 
 8.7 
 
 17.6 
 7.32 
 7.34 
 
 Unstained 
 
 do 
 
 Stained 
 
 Unstained 
 
 do 
 
 Stained 
 
 6,295 
 7,729 
 8,902 
 7,322 
 10,932 
 11,295 
 
 10,040 
 13,736 
 14,081 
 11,679 
 16,759 
 17,858 
 
 1,559 
 1,792 
 1,883 
 1,785 
 2,187 
 2,374 
 
 9.6 
 9.8 
 9.4 
 8.5 
 11.97 
 11.77 
 
 857 
 954 
 852 
 772 
 910 
 883 
 
 They show that for the same moisture content the heavily stained 
 shortleaf pine was slightly weaker, less tough, and showed less 
 surface hardness than the unstained. In the longleaf pine, which 
 
 1 Circular 192, U. S. Forest Service, "The Prevention of Sap Stain in 
 Lumber," by Howard F. Weiss and Charles T. Barnum. 
 
30 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 was only slightly stained, the differences in strength, toughness, 
 and hardness between stained and unstained boards were too 
 slight to be noticed. Immense numbers of minute spores soon 
 form on the freshly cut sapwood and are blown by the wind like 
 dust until they alight on other wood, when they start to germ- 
 inate. It is chiefly in this way that the stain is spread and be- 
 cause of the enormous numbers of spores produced, lumber 
 cut during the warmer months has little chance of drying without 
 being attacked. So far, then, as this cause is concerned, we may 
 consider sap stain as analogous to decay, but the results as shown 
 above are decidedly different. 
 
CHAPTER III 
 
 THE EFFECT OF THE STRUCTURE OF WOOD UPON ITS 
 INJECTION WITH PRESERVATIVES 
 
 The Effect of Density upon Absorption. — It is well known that 
 the structure of wood has a very pronounced effect upon the 
 manner in which preservatives can be injected into it, so that 
 all kinds of wood cannot be handled in the same way and uni- 
 form results secured. It is the purpose of this chapter to show 
 the effect of the various structures so far as they are known upon 
 the diffusion of the preservatives, without going into a detailed 
 discussion of wood formation and composition. 
 
 For our purposes we may consider wood as being composed 
 of a mass of small, hollow fibers or cells of various sizes and 
 forms more or less closely packed together. The materials of 
 which they are composed are chiefly cellulose and lignin. These 
 substances, in themselves, are heavier than water, so that, were 
 the cells solid, the wood would sink in water. The weight or 
 density of wood is largely dependent upon the amount of air 
 space in the various cells' and it is this confined air which gives 
 wood its buoyancy. Thus in woods like ebony or hickory the 
 cells are dense and the air spaces small so that a cubic foot of 
 such wood contains a large percentage of solid wood substance. 
 In other varieties like white pine or cedar the cells have larger 
 air spaces and there is a smaller percentage of solid wood sub- 
 stance so that the wood is light and will readily float in water. 
 Painstaking research has shown that the density of wood sub- 
 stance irrespective of species is practically the same, being 
 about 1.55 specific gravity, or about 97 pounds per cubic foot. 
 
 It would appear that woods which are light in weight and 
 hence have considerable air space would absorb preservatives 
 more readily than woods which are heavy. Such, however, is 
 not the case, hence the ability of wood to absorb preservative 
 cannot be judged from its density or weight. In other words, 
 the resistance of wood to injection with preservatives has little to do 
 
 31 
 
32 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 with the dry weight of the wood. This is an important fact on 
 which many writers and engineers have been lead astray. Under 
 identical conditions of test white spruce heartwood which weighed 
 oven-dry 25 pounds per cubic foot absorbed only 6 pounds of 
 creosote per cubic foot, while heart longleaf pine weighing 39 
 pounds absorbed 13 pounds of the oil. Numerous other ex- 
 amples could be given which prove this beyond all reasonable 
 doubt. There seems, however, to be a rather direct relation 
 between density and absorption in wood of the same species. 
 Thus red oak, for example, which is comparatively light in 
 weight, will absorb more preservative than red oak which is 
 heavy. The difference is not great and has little practical sig- 
 nificance. Similar observations have been made on maple.' 
 Whether or not the relationship will hold for all species cannot 
 be stated. As the dry weight of certain woods depends on the 
 rate at which the woods have grown, a relationship between 
 absorption and rate of growth can be said to exist, although this 
 is not strongly defined. 
 
 Absorption by the Cell Walls. — It has been held that the cell 
 walls of wood do not absorb creosote, hence the amount of this 
 oil which can be impregnated into wood depends upon the amount 
 of air space which the wood contains. This claim is not strictly 
 true. Tests made at the Forest Products Laboratory show that 
 the cell walls are capable of absorbing creosote although the 
 amount is very small and of little significance in practical opera- 
 tions.^ In these tests a number of pieces of hard maple, yew and 
 hemlock, 2 3/4 X 3/4 X 1/8 inch were dried in an oven at 212° F. for 
 24 hours then placed in a desiccator and weighed when cold to 
 the nearest 0.001 gram. The volume of each piece was then deter- 
 mined by displacement and the specimens impregnated with 
 water-free creosote for 1 hour under a pressure of 250 pounds 
 per square inch and temperature of 175° F. The volumes of the 
 pieces after treatment were then determined and compared with 
 the volumes at the same temperatures before treatment. 
 
 The average increases in volume resulting from the treatments 
 of the three species in percent of the volumes before treatment, 
 were: 
 
 'Bulletin 126, U. S. Forest Service, "Experiments in the Preservative 
 Treatment of Red Oak and Hard Maple Cross-ties." F. M. Bond, 1913. 
 
 ' Circular 200, U. S. Forest Service, "The Absorption of Creosote by the 
 Cell Walls of Wood," by C. H. Teesdale. 
 
THE EFFECT OF THE STRUCTURE OF WOOD 
 
 33 
 
 Percent 
 
 Yew, heartwood 6.81 
 
 Yew, sapwood 10.70 
 
 Hemlock, heartwood 7.30 
 
 Hard maple, heartwood 8.14 
 
 The Effect of Sapwood and Heartwood upon Injection. — The 
 
 sapwood is commonly defined as that portion of the tree in which 
 the wood cells are alive and perform vital functions. It always 
 occurs immediately under the bark and can usually be distinguished 
 from the heartwood by the Hghter color. The width of the sap- 
 wood varies considerably in the different kinds of wood, being 
 very narrow in such varieties as chestnut or black locust and wide 
 in others like loblolly pine and red gum. This difference has a 
 very direct bearing on the treatment of wood, because the sap- 
 wood of all species can be readily impregnated with preservatives. 
 In some varieties the sapwood is easy to inject while the heart- 
 wood is practically impenetrable. This is typified by the red gum 
 and Douglas fir. In other woods like hemlock, there is little 
 difference between the resistance to penetration offered by the 
 sap and heartwood. These differences are often very marked, as 
 is shown in Table 3. The specimens of wood were selected from 
 various species, dried to the same degree of moisture, and all 
 impregnated at the same time in a treating cylinder at the 
 Forest Products Laboratory by the full-cell creosote process. 
 
 Table 3. — The Absobption of Coaij-tar Creosote by the Heart-wood 
 
 AND Sapwood of Various Woods Given Exactly the 
 
 Same Treatment. (Size of Specimens 2 X 2 X 12 
 
 Inches; Six in Each Test) 
 
 Kind of wood 
 
 Average absorption of creosote, pounds 
 per cubic foot 
 
 Heartwood 
 
 Sapwood 
 
 Douglas fir 
 
 4.38 
 
 14.46 
 
 
 West, yellow pine . 
 
 16.14 
 
 28.74 
 
 
 Longleaf pine 
 
 12.90 
 
 34.20 
 
 
 Lodeepole pine 
 
 12.84 
 
 31.56 
 
 
 Eastern hemlock 
 
 17.28 
 
 18.78 
 
 
 Alpine fir 
 
 3.66 
 
 4.14 
 
 
 White spruce 
 
 6.42 
 
 8.22 
 
34 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 The reason why sapwood as a rule is more permeable to the 
 passage of preservatives is not definitely known. So far as 
 the size, shape and strength of the cells are concerned there is 
 little difference between those in the sapwood and those in the 
 heartwood. It is quite likely, therefore, that the reason must 
 be looked for in changes which occur in the composition of the 
 cell walls when they are transformed into heartwood cells, or 
 in the cell contents or in the character of the pits in the cell 
 walls which become changed in position and more or less per- 
 manently set. Much further work remains to be done before the 
 true cause is determined. 
 
 The Effect of Summerwood and Springwood upon Injection. — 
 All of the commercially important American woods grow by 
 adding a successive layer of wood with each successive year of 
 life. These layers are concentric and are called "annual rings." 
 Normally, one such annual ring or layer is produced each year, 
 so by counting the number of such rings from the center to the 
 outside of a piece of wood, the number of years it took to grow 
 the wood can be directly determined. In most varieties of trees 
 there is a vast difference between the character of the wood 
 in the annual ring formed in the spring and that formed in the 
 summer. The former is called " springwood," the latter " summer- 
 wood." Thus in longleaf pine, for example, the cells in the 
 springwood have much thinner walls than those in the summer- 
 wood. This of course makes the springwood much lighter and 
 weaker than the summerwood and causes the banded appearance 
 so noticeable in edge or "comb-grained " yellow pine lumber. In 
 other coniferous woods like white spruce the difference in the cells 
 of the spring and summerwood is not so pronounced and hence 
 such wood is much more uniform. The same differences occur in 
 certain hardwoods like oak, ash, etc., where many of the cells in 
 the springwood are so large as to be called "pores" or "vessels." 
 In other hardwoods like the maple, beech, birch, etc., the dif- 
 ference between the spring and summerwood is slight and hence 
 these woods possess greater uniformity. In all woods which have 
 no marked difference in the spring and summerwood the injec- 
 tion of preservatives is fairly uniform throughout the entire annual 
 ring. The beech, maples, firs, spruces, etc., fall in this class. 
 (See Plate IV, Fig. D.) Great irregularity in penetration and 
 absorption occurs in the other types of wood. Thus in longleaf 
 pine, red oak, ash, etc., the treatment will often appear in bands 
 
Plate IV 
 
 Fig. a. — ^Longleaf pine boards piled solidly after one month's exposure to 
 sap stain fungi. Boards on left, untreated; boards on right dipped in a weak 
 solution of mercuric chloride. Note absence of stain. (Forest Service 
 photo.) 
 
 Fig. B. — Cross section through red oak — a "ring porous" wood. Note 
 arrangement of pores mostly in the spring wood. Note also clearness of 
 pores. X50. (Forest Service photo.) 
 
 (Facing page 34.) 
 
Plate IV 
 
 
 Fig. C. — Cross section through maple — a "diffuse 
 pores scattered through entire width of annual ring, 
 photo.) 
 
 porous" wood. Note 
 X50. (Forest Service 
 
 Fig. D. — Cross section through spruce 
 absence of pores. Larger openings are 
 (Forest Service photo.) 
 
 —a "nonporous" wood, 
 'resin ducts" or cells. 
 
 Note 
 X 50. 
 
 Fig. E. — Cross section through white oak. Note pores clogged with "ty- 
 loses." Compare with red oak. X 50. (Forest Service photo.) 
 
 Pig. F. — Radial section through pine. Note bordered pits or "eyes," also 
 how fibers fit into one another. Vertical cells on extreme left are medullary 
 or "pith ray" cells. X 250. (Forest Service photo.) 
 
THE EFFECT OF THE STRUCTURE OF WOOD 35 
 
 (in a cross section view) or streaks (in a radial view) . This is 
 because the spring and summerwood offer different resistances to 
 the passage of the preservative. In red oak and ash most of the 
 preservative will be found in the springwood, while in longleaf 
 pine most of it occurs in the dense summerwood. The exact 
 reasons why these differences occur will be described further 
 on. It follows, therefore, that the rate at which certain woods 
 grow affects very appreciably the uniformity of the treatment 
 secured. When the tree grows rapidly, the annual rings are 
 comparatively wide, hence the bands of heavy and light treated 
 wood are pronounced. (See Plate V, Fig. A.) When growth has 
 been slow these rings are narrower and the bands are much 
 less pronounced. (See Plate V, Fig. B.) In general, therefore, the 
 species which have pronounced differences in the spring and sum- 
 merwood have a much greater irregularity in the treatment of 
 the annual rings than those which are of a more uniform 
 stucture, especially when of rapid growth. It is largely because 
 of these differences that the number of rings per inch allowed 
 in certain classes of material, such as paving blocks, is specified. 
 
 The Effect of Vessels or "Pores" on the Treatment of Wood. — 
 All varieties of American "hardwoods" possess elongated cells 
 called "vessels" or "pores." These are characteristic of hard- 
 woods and form a reliable means of distinguishing such woods 
 from the "conifers" in which the vessels are entirely absent. 
 These pores occur in two ways: first, scattered through the annual 
 rings, and second, as bands of "rings" in the springwood of the 
 annual ring. Because of this difference the hardwoods are 
 commonly classified as diffuse porous (maple, birch, beech, etc.) 
 and ring porous (oak, ash, hickory, etc.). These pores, which 
 are often so long as to resemble capillary tubes, are easily filled 
 with preservative and offer ready channels for conducting the 
 preservative into the wood.^ Thus in red oak the pores are so 
 long that it is possible to blow through a piece of this wood; 4 
 feet or more in length. It can be easily understood, therefore, 
 why such woods readily absorb preservatives and why the 
 character of the treatment secured depends so much upon the 
 arrangement of the pores. 
 
 The Effect of Tyloses on the Treatment of Wood. — It frequently 
 happens that the vessels described above are clogged with a cell 
 
 ' When the pores are filled with "tyloses" this statement does not hold. 
 See discussion under "tyloses." 
 
36 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 growth which prevents the passage of air or liquids through them. 
 This growth is characteristic of certain kinds of wood like white 
 oak and black locust and renders them practically impervious to 
 absorption. It is caused by cells, called "tyloses," growing into 
 the vessels. (See Plate IV, Fig. E.) These may occur even in the 
 sapwood and when they are present the vessels cannot be pene- 
 trated. In some kinds of wood like white oak, tyloses are uni- 
 form throughout, only a few vessels being without them. In 
 other varieties, like black oak, tyloses occur irregularly through 
 the wood. Thus in certain parts of a stick the vessels may be 
 few and the preservative will readily enter, while in another part 
 the tyloses may fill the vessels and absolutely prevent any 
 entrance of the preservative. In such cases a very irregular 
 diffusion of the preservative naturally occurs. There is no way 
 of telling to what extent the tyloses occur in these woods ex- 
 cept by a careful microscopic examination. From a large num- 
 ber of microscopic examinations of various American woods it 
 is possible to class them into three groups depending upon the 
 presence or absence of tyloses.^ 
 
 Group 1 — Tyloses absent — the maples, birches, blue beech, 
 flowering dogwood, holly, silverbell, black and water gums, 
 black and red cherry, basswood, persimmon, honey locust. 
 
 Group 2 — Tyloses few — yellow buckeye, beech, red gum (sap), 
 yellow poplar, magnolias, sycamore, black cottonwood, eucal- 
 yptus (blue gum), white and Oregon ashes, and the elms. 
 
 Group 3 — ^Tyloses abundant — large tooth aspen, hardy catalpa, 
 desert willow, green, pumpkin and blue ash, mockernut, water 
 pignut, shellbark, bitternut, nutmeg and shagbark hickories, 
 butternut, black walnut, red mulberry, blackjack, white, Garry, 
 overcup, valley, burr, cow, post and swamp white oaks, black 
 locust, and osage orange. 
 
 Tyloses were also found very scatteringly in the pines, but in no 
 other conifers examined. 
 
 The Effect of Resin Ducts on the Treatment of Wood. — As 
 mentioned above, conifers do not possess vessels or pores. Some 
 of them do, however, have a structure which, so far as a penetra- 
 tion' with preservatives is concerned, functions like pores. This 
 structure is called a "resin duct," and as the name implies, it is 
 a duct or " pore " usually producing and containing resin. Except 
 when the ducts are clogged with resin or some other obstruction, 
 
 ' From examinations by Eloise Gerry, U. S. Forest Products Laboratory. 
 
Plate V 
 
 Fig. a. — Cross section through a lolboUy pine tie. Note wide rings 
 showing rapid growth, also note sharp transition of spring wood and 
 svimmerwood. 
 
 Fig. B. — Cross sections through two long leafpine stringers. Note 
 narrow rings especially in sapwood, showing slow growth. (Forest Service 
 photo.) 
 
 (Facing page 36.) 
 
Plate V 
 
 Fig. C. — Cross section through the summerwood of larch (greatly magni- 
 fied) showing slits in cell walls. (Forest Service photo.) 
 
 Fig. D.- 
 
 -Showing ease with which chestnut peels in the spring, 
 photo.) 
 
 (Author's 
 
THE EFFECT OF THE STRUCTURE OF WOOD 37 
 
 they afford channels for the ready penetration of the preserva- 
 tive. Some experiments have been made at the U. S. Forest 
 Products Laboratory to determine the effect of resin in the 
 ducts upon the entrance of coal-tar creosote. It was found that 
 such resin, particularly when it is old, has a very marked effect 
 in retarding the entrance of the oil. When the test blocks of 
 wood were first extracted with a resin solvent and then dried, the 
 creosote entered, the wood very easily. 
 
 The position of the resin ducts in the wood affects very materi- 
 ally the character of the treatment. Thus, in longleaf and lob- 
 lolly pines the resin ducts are largely in the summerwood and 
 because of this the summerwood is more penetrable than the 
 springwood even though it is much denser. Some exacting 
 tests have been made by C. H. Teesdale to secure definite in- 
 formation on this point. Pieces of the summerwood of loblolly 
 pine which had a specific gravity of 0.95 and pieces of springwood 
 cut from the same specimens which had a specific gravity of 
 0.39 were impregnated at the same time with coal-tar creosote. 
 The summerwood absorbed 1.8 times as much creosote as the 
 springwood. There is little doubt but what the resin ducts had 
 much to do with this difference and it is largely because of them 
 that longleaf pine paving blocks often show a "banded" treat- 
 ment. In redwood the ducts occur mostly in the springwood and 
 in this species a better absorption and penetration of preservative 
 is secured in the springwood than in the summerwood. 
 
 The resin ducts also occur in certain species in the medullary 
 or pith rays. These are layers of cells which radiate from the 
 circumference of the tree to the center. In all coniferous woods 
 which possess such ducts, good radial penetration of the preserva- 
 tive is secured (from the outside toward the center) . This fact 
 is of considerable importance commercially because in order to 
 secure good treatments, especially in round timbers like poles or 
 piles, it is essential to peel all of the bark off them; otherwise 
 the ends of the ducts will be plugged by the bark and little or 
 no penetration at that point secured. It is believed that care- 
 lessness in peeling such woods is one cause of the rapid destruc- 
 tion of creosoted piling, as it leaves streaks of untreated wood 
 extending to the interior of the stick and thus affords avenues of 
 attack by marine borers. Pieces of wood 2 X 4 X 25 inches 
 were impregnated by Teesdale with coal-tar creosote under 
 identical conditions. Those which contained radial resin ducts 
 
38 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 were penetrated radially from one-fourth to three-fourths as 
 far as' they were longitudinally. In those woods which had 
 no radial ducts, the radial penetration varied from one- 
 twentieth to one one-hundred twentieth of the longitudinal 
 penetration. Practically all of the pines belong to the former 
 class, while many of the larches, firs, hemlocks, and spruces 
 belong to the latter. 
 
 The Effect of Pits upon Injection. — The penetration of pre- 
 servatives in woods containing vessels and resin ducts can largely 
 be explained by their presence. In certain woods, however, 
 where neither of these are present or where they are restricted, 
 — ■- the manner in which penetration 
 
 >^S^^| (^^^ ^ occurs is not easy of explanation. 
 
 According to Bailey,^ " whenever pre- 
 servatives are injected rapidly into 
 green or seasoned wood, the pene- 
 tration takes place primarily through 
 the cavities of the cells, and the pre- 
 servatives pass from one cell to 'an- 
 other through the bordered pits." 
 These bordered pits may be likened 
 Fig. 4 . — Diagrammatic *« microscopic " valves " occurring in 
 drawing of pit membrane the walls of the cells. (See Plate IV, 
 
 tTons.Trom Bdley.f*"" Fig- ^0 When the cells are alive as 
 
 in sapwood, the passage of liquids 
 through the pits is more or less controlled by the "torus," 
 which is a thickening of the middle portion of the cell wall. 
 When the cells are dead, as in heartwood, the torus ceases to 
 move and frequently becomes fastened to the pit, thus more or 
 less effectively closing the opening to the passage of liquids. 
 Bailey further states that the membranes of the bordered pits 
 are not always entire but possess numerous minute perforations 
 (Fig. 4). "In green wood the bordered pits and membranes are 
 very permeable to aqueous solutions, but are comparatively 
 impervious to undissolved gases and to oils. This is due to 
 capillary or surface tension phenomena and the valve-like action 
 of the torus." The experiments of this investigator throw much 
 valuable light upon the perplexing problem of the penetration of 
 wood and account for some of the results secured in its treatment. 
 
 ^ The Preservative Treatment of Wood," by Irving W. Bailey, Harvard 
 School of Forestry, 1913. 
 
THE EFFECT OF THE STRUCTURE OF WOOD 39 
 
 The Effect of Cell Slits upon Penetration. — Experiments con- 
 ducted by Tiemann of the U. S. Forest Products Laboratory^ 
 show that the walls of wood cells frequently slit open in drying. 
 These slits as a rule are more discernible in thick-walled cells 
 than in thin-walled cells. (See Plate V, Fig. C.) Their presence 
 has been advanced by Tiemann and the author a a possible means 
 of aiding certain liquids to penetrate wood substance, because they 
 furnish points of weakness in the cell wall. 
 
 The Effect of the Chemical Composition of the Cell Wall 
 upon Absorption. — All the phenomena noted above relate to the 
 physical structure of wood in relation to its absorption of liquids. 
 In addition to them, it is probable, although by no means proven 
 as yet, that the composition of the cell walls in various woods 
 exerts a strong influence upon the manner in which they absorb 
 preservatives. Thus, when the walls are reenforced by subse- 
 quent deposits of wood substance, it is quite likely that a dif- 
 ferent effect is produced than where no such thickening occurs. 
 In addition, the chemical composition of the various layers may 
 be different, as well as the character of the materials deposited 
 upon them. Their combined action, therefore, in retarding 
 oils and water solutions may be a variable one, and hence the 
 character of the absorbtion and penetration obtained may also 
 vary. To just what extent this is true is not known. This 
 problem still furnishes a fertile field for original research. 
 
 It can be seen from the above discussion that the manner in 
 which preservatives penetrate wood is very complex. No single 
 factor in itself entirely explains it, so it can be accounted for only 
 by taking several or all of them into consideration. 
 
 ' Bulletin 120, American Railway Engineering Association, 1911. 
 
CHAPTER IV 
 
 THE PREPARATION OF TIMBER FOR ITS PRESERVA- 
 TIVE TREATMENT 
 
 The Cutting Season. — There has been much discussion con- 
 cerning the effect of cutting timber in various seasons upon its 
 durabihty. The consensus of opinion gives preference to winter. 
 This is undoubtedly correct in that timber cut at this period 
 is more hable to be in better condition than that cut at any other 
 season. In so far as the contents of the wood cells are con- 
 cerned, timber cut in winter, as a rule, contains iis largest per- 
 centage of organic materials, such as starch, these being stored 
 in the cells as available plant food for the next spring. These 
 organic materials are also readily attacked by wood-destroy- 
 ing organisms so that a given amount of winter cut wood, other 
 things being equal, contains more food material for these de- 
 structive agents than wood cut at other times of the year. 
 
 On the other hand, wood cut in winter is least subject to im- 
 mediate insect and fungous attack because, during winter, insect 
 and fungous activities are at a minimum. Moreover, freshly 
 cut wood is less able to offer resistance to the attacks of these 
 agents than thoroughly seasoned wood. 
 
 Aside from danger from insect and fungous attack, the problem 
 of seasoning is also of great moment, and, as will be shown later 
 on, wood cut during spring, summer, and early autumn dries 
 much more rapidly than wood cut in winter. This rapid drying, 
 unless it is properly safeguarded, will often cause green timber to 
 check and split, thus not only weakening the wood but also 
 exposing more of its surface to attack. 
 
 The season of cutting also has a marked effect upon the 
 reproductive power of the forest, especially if the forest is com- 
 posed of species that sprout from the stump, like most of our 
 hardwoods. Sprouts from winter cut stumps are usually much 
 more vigorous and thrifty than those from stumps cut at other 
 seasons; in fact, the sprouting capacity of stumps can often be 
 killed by cutting timber in summer or early fall. 
 
 40 
 
THE PREPARATION OF TIMBER 41 
 
 Contrary to popular belief timber cut in winter often con- 
 tains as much water and at times, more water, than timber cut 
 at other periods. The common expressions that in winter the 
 "sap is down" and in summer "up" account for this fallacy, 
 whereas in reality it is only dormant, so that if the tree is in- 
 jured in this period the sap does not readily exude from it. The 
 author made some careful tests along these lines when cutting 
 chestnut timber for poles in Maryland, and found that those cut 
 in winter actually contained more water than those cut in 
 summer. 
 
 Generally speaking, it is easiest to remove felled timber from 
 the forests in winter because of climatic and labor conditions, 
 although in the South, where no marked changes occur, this of 
 course is not true. In certain northern states, as in cedar opera- 
 tions in the Lake Region, it is almost impossible to log except in 
 winter. Furthermore, the large amount of timber cut by farmers 
 is felled by them during the winter months because they are not 
 then engaged in caring for their food crops. 
 
 Peeling Timber. — Practically all preservative processes require 
 the complete removal of bark before the wood can be successfully 
 treated. Generally, the best time to remove the bark is im- 
 mediately after the tree is felled. In sawed products the bark 
 usually is removed at the mill in slabbing the log. Bark can be re- 
 moved most easily in the spring (see Plate V, Fig. D), but adheres 
 tenaciously to the wood when cut at other periods. It is com- 
 paratively easy for this reason to tell timber cut in the spring. 
 The early removal of the bark lessens the weight of the product, 
 decreases the danger from insect and fungous attack, and causes 
 the wood to dry more rapidly. Because of the great resistance 
 of bark to penetration by liquids, it is essential to carefully and 
 completely remove it, if good results in treatment are to be 
 secured. This is particularly true for those woods which are 
 penetrated readily in a radial direction, as the gines. For species 
 like the tamarack, spruce, etc., whose radial penetration is small, 
 this precaution is not so essential. The author has seen pine pil- 
 ing impregnated with 18 pounds of creasote to the cubic foot that 
 had absolutely no penetration of the oil under strips of bark less 
 than 1/16 inch in thickness. (See Plate VI, Fig. A.) Theinnerbark 
 or "skin' ' is particularly resistant, and it is believed that its presence 
 is at times one cause contributing to the rapid failure of those 
 treated piles which are destroyed after a few years' service. Too 
 
42 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 often the treating engineer counts on the bark becoming loose 
 during the treatment in the cylinder, and although this frequently 
 occurs, nevertheless it often adheres firmly to the wood and thus 
 results in poor workmanship. 
 
 It sometimes happens that better treatments can be secured 
 by seasoning wood with the bark on, rather than with the 
 bark off. This was true in some tests made by the Chicago 
 and Northwestern Railroad on hemlock and tamarack ties at 
 Escanaba, Mich. It appeared that the ties peeled immediately 
 after cutting seasoned so rapidly that the outer layers of the 
 wood hardened and became much more resistant to the absorption 
 of the preservative than those in which the bark was removed 
 just before the ties were run into the treating cylinder. This, 
 however, is an exception to general practice. 
 
 Generally, bark is removed by hand, the only tools being 
 a spud, draw knife, or axe. There is a good opportunity for the 
 invention of some machine that will economically and satisfactor- 
 ily remove bark and thus decrease the labor involved in present 
 methods. 
 
 Seasoning Timber. — Wood in all living trees contains water. 
 The amount of water thus contained varies with the kind of wood, 
 the conditions under which it grew, and the season. It fre- 
 quently happens that in the sapwood, and sometimes in the heart- 
 wood, the weight of the water is more than the weight of the wood 
 substance itself. Thus the gums when dried may weigh less 
 than half their weight at the time of cutting. In general, 
 as soon as timber is cut it begins to lose the water it contains. 
 This loss of water is called "seasoning." In addition to the loss 
 of water, other changes occur, such as a fixation or transformation 
 of organic and inorganic materials stored in the wood, and an 
 apparent "oxidation" of the wood substance. The objects of 
 seasoning are, in brief: 
 
 1. To prevent injury by insects and decay before the timber is 
 placed in service. 
 
 2. To increase the durability of timber in service. 
 
 3. To prevent shrinking and checking of the wood in service. 
 
 4. To increase the strength of the wood. 
 
 5. To decrease the weight of the wood and hence reduce shipping 
 charges. 
 
 6. To prepare the wood for its injection with preservatives and 
 for other industrial uses. 
 
THE PREPARATION OF TIMBER 43 
 
 It is well known that if wood can be kept dry it will not decay. 
 House furniture, for example, under ordinary conditions of use 
 will, so far as decay is concerned, last indefinitely. It is solely 
 because of their protection from moisture that the wooden coffins 
 used by the Egyptians have been preserved to us. Water in 
 wood is an absolute requirement for decay. Wood which can 
 be kept dry will never decay. Just how much water in wood is 
 necessary in order to meet the requirements of wood-destroying 
 fungi is not known, but from a few tests which the author has 
 made it appears that it is in general more than 20 percent. 
 
 It has almost unanimously been held that seasoned wood 
 placed in conditions of service where it is subject to decay wil- 
 last longer than unseasoned wood. While this is sometimes 
 true, nevertheless the importance which has been attached 
 to air seasoning as a means in itself of prolonging the life of wood 
 has probably been exaggerated. Authentic records on posts, 
 poles, ties, and mine timbers kept by the Forest Service indicate 
 that there is little or no difference in their durability whether 
 they were placed green or air seasoned. 
 
 If green timber is used for construction purposes, it will almost 
 invariably lose water and hence check, shrink, and warp more or 
 less severely. In order to avoid such defects, it is policy to use 
 seasoned wood in place of green in all classes of construction 
 where they prove objectionable. Furthermore, wood which 
 has been seasoned prior to injection with perservative is far less 
 liable to check on the surface and thus expose the untreated 
 wood. 
 
 The effect of water in wood upon its strength is discussed in 
 Chapter XVIII. The decrease in weight due to seasoning is so 
 large as to warrant holding the timber until seasoned before ship- 
 ment is made. This fact is now so well recognized that it has be- 
 come common practice, but on account of unfavorable conditions 
 surrounding the seasoning of wood at the place whiere it is cut, the 
 shipment of green material is sometimes imperative. A single 
 carload of 30-foot chestnut poles if shipped seasoned rather than 
 green would save at least 150 pounds of freight per pole, or, 
 counting 50 poles per car, a total of 7500 pounds. This saving 
 even on short hauls often more than pays for the cost of seasoning 
 the poles and holding them in storage awaiting shipment. What 
 is true for poles is true even to a greater extent for smaller 
 products because they season more thoroughly. 
 
44 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 It is in the preparation of wood for injection with preservatives 
 that seasoning plays a very important part, as it is quite essential 
 to remove some or most of the water from the wood before the 
 preservative can be injected. 
 
 Water may be considered as existing in wood in two forms: (1) 
 as "free water" in the cell cavities and (2) as "confined water" 
 in the cell walls. When wood begins to season it is the free 
 water which is first lost. Wood can lose all of this free water 
 without its strength being affected. Just as soon, however, as 
 water starts to leave the cell walls the strength of wood begins 
 to increase very rapidly, and checking, warping, and splitting are 
 liable to occur. The point where this occurs has been called by 
 Tiemann the "fiber-saturation point." It varies in the different 
 species but in general ranges from 25 to 30 per cent moisture. 
 When the free water has left the wood, the wood of course con- 
 tains a larger air space or volume which can later be occupied by a 
 preservative like creosote. This may be illustrated as follows: 
 Assume the oven-dry weight of shortleaf pine is 32 pounds per 
 cubic foot, that solid wood substance weighs 97 pounds per 
 cubic foot, that green shortleaf pine contains 21 pounds of water 
 per cubic foot; then about two-thirds of a cubic foot of green 
 pine would be wood substance and water, leaving about one- 
 third of the volume air space. If, now, all the free water were 
 removed, almost two-thrds of the cubic foot of wood would be 
 air space capable of occupancy by the preservative. 
 
 Aside from the loss of water which takes place in seasoning, 
 other changes occur. The bordered pits become more or less 
 ruptured, or changed in position, so that passage of liquids 
 through them is facilitated or retarded. Furthermore, the wood 
 cells frequently check as well as the surface of the wood. As a 
 result of these changes which occur in seasoning wood, practically 
 all processes now call for some kind of a seasoning treatment 
 before the preservative is injected. The chief exception occurs 
 in the Boucherizing process, which is at present of no com- 
 mercial importance in the United States. Five methods of 
 seasoning wood are now practised : Open-air seasoning, seasoning 
 in hot air, seasoning in saturated and superheated steam, and 
 seasoning in oil. 
 
 Open-air Seasoning. — Open-air seasoning, as the term implies, 
 consists simply in piling the timber out of doors where it is 
 exposed to the atmosphere. When its moisture content reaches 
 
THE PREPARATION OF TIMBER 45 
 
 an equilibrium with the atmospheric moisture, the wood is said 
 to be "air seasoned." It can thus be seen that the amount of 
 water in air-seasoned wood varies considerably. Thin pieces of 
 wood 2 inches or less in thickness in our northern climates, 
 when air seasoned, contain about 10 to 15 percent of water. 
 Thicker pieces like poles, ties, etc., are, under the same 
 conditions, "air seasoned" when they contain 25 to 35 percent of 
 water. Some Douglas fir bridge stringers 8 inches X 16 inches 
 in cross section contained over 25 percent of moisture after being 
 exposed to the atmosphere for 2 years. 
 
 The open-air seasoning of wood is the method most commonly 
 practised in the United States to prepare it for injection with 
 preservatives. It is cheap, safe to operate, and very efl&cient. 
 The chief objections to it are the long length of time the wood 
 must be held before it seasons, thus tying up capital in wood 
 and yardage, and dangers from fire, insects, and decay while 
 stored during the seasoning period. In some parts of our 
 country where the climate is warm and damp it is impossible to 
 air-season certain woods without having them attacked by 
 incipient decay. Other objections to air seasoning are an inability 
 to fill "rush orders" and injury from checking, although this 
 latter objection can be largely overcome by proper methods of 
 piling. 
 
 To most efficiently season wood in the open air, it is necessary 
 to subject it to a free circulation of air. Stagnant air is very 
 prone to foster decay. The seasoning yards should, therefore, 
 be in situations exposed to the sun and wind. All of the timber 
 should be raised off the ground and should be piled as openly as 
 possible without producing too rapid drying, which might result 
 in serious checking or splitting. Another precaution is to keep 
 the yard free from water, vegetation, and decaying wood. 
 
 The rate at which wood seasons depends upon many factors, 
 chief of which is the time of the year. Spring and summer are 
 in general the two periods when most rapid seasoning occurs. 
 More detailed information for the various forest products is given 
 in the following pages under the discussion of these products. 
 When wood has once air seasoned, any water which it might ab- 
 sorb from rains, for example, is quickly lost. Air-seasbned poles 
 tested by the author absorbed 15 pounds of water during a 
 thunderstorm but lost all of it within 24 hours after the rain 
 stopped. It is by no means necessary to season wood until it 
 
46 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 has lost all its free water before it is in satisfactory condition 
 for treatment. Large products such as ties and poles may have, 
 when "air-seasoned," an average of 30 percent of water, but 
 the distribution of this water may vary from 5 to 10 percent 
 in the outer layers of wood as a minimum to 40 or 50 percent in 
 the inner layers as a maximum. If a tie or pole is of such a 
 nature (as is customary) that its interior cannot be treated 
 even if it is dry, little or no advantage is gained in attempting 
 to hold it until this condition of uniform dryness is reached. 
 The object, therefore, in open-air seasoning should be to cut 
 the period of drying as short as possible without decreasing the 
 penetration of the preservative. No fixed time can be given 
 for this, as it depends on too many variables which must be 
 worked out for the conditions at each plant. 
 
 Hot-air Seasoning. — By "hot-air seasoning" is meant kiln 
 drying the wood. This method is now only practised in the 
 United States on certain kinds of lumber and small manu- 
 factured products. It is rarely if ever used for large products 
 such as piles, poles, and ties. In Europe, however, the method 
 is sometimes employed, especially as a final drying for timber 
 already partly seasoned in the open air. It 'is felt that the 
 method will not become common practice in our country be- 
 cause equally . as good if not better results can be secured in 
 shorter time and at less expense by other means. The method 
 employed in hot-air or kiln drying consists in placing the wood 
 in a retort or kiln, where the air is usually heated by means of 
 steam coils. Circulation of the air is provided for in various 
 ways, either by blowers, or by cooling the air on the sides of 
 the kiln, or by drawing in air through vents in the bottom of 
 the kiln and permitting the hot air to escape through vents 
 in the top. Such treatment results in removing the water from 
 the wood in much shorter time than open-air seasoning and in 
 addition warms the wood for the entrance of the preservative. 
 Wood so heated is, however, liable to check and warp seriously 
 or case-harden, thus becoming weak and brash. For the treat- 
 ment of small products of comparatively high value, this method 
 gives very satisfactory j-esults, but for dimension stock or products 
 it has little to commend it. 
 
 Seasoning in Saturated Steam. — Next to open-air seasoning, 
 seasoning in saturated steam is in most extensive use in the 
 United States as a means of drying wood for the injection of 
 
THE PREPARATION OF TIMBER 47 
 
 preservatives. When properly done this method gives quick 
 and satisfactory results. Its chief advantages are the ease, 
 quickness, and comparative cheapness with which the water 
 can be dr^wn from the wood, the warming of the wood prior 
 to its impregnation, and the sterilizing of the wood. When 
 this method is practised a large storage capacity for wood and 
 a large stock on hand are not necessary. Furthermore, "rush 
 orders" can be taken care of and dangers peculiar to open-air 
 seasoning are avoided. If steamed at too high temperatures 
 or for too long a period, considerable injury may result to the 
 strength of the wood. Steaming wood, in itself, does not re- 
 move water from the wood. On the other hand, it may add 
 water, as shown in Table 34. In practice, to remove the water 
 a vacuum is drawn. This lowers the boiling point of water 
 and materially hastens the rate at which it leaves the wood. 
 
 Structural timbers, when seasoned for the injection of pre- 
 servatives by the use of saturated steam, are loaded on cylinder 
 cars or "buggies" and run into the treating cylinder, which is 
 then closed and live steam admitted. The pressures used are 
 about 20 to 40 pounds per square inch. The wood is kept in 
 the steam bath for various periods, depending upon the judg- 
 ment of the operator, and the- kind and form of timber he is 
 heating. It ranges from about 2 to 3 hours for ties to 
 10 hours or even more for piling. Tests niade at the 
 U. S. Forest Products Laboratory indicate that 5 to 8 hours 
 are required to heat ties to the center by this method. After 
 the steam bath a vacuum of 24 to 26 inches is drawn in the 
 cylinder by means of a pump, and at the end of this period the 
 wood is ready for injection with the preservative. The length 
 of time the vacuum is held varies greatly, but is usually from 
 1/2 to 2 hours. Nothing is gained by holding it after the 
 wood has once reached a temperature below which no further 
 heat units leave the wood. 
 
 Seasoning in Superheated Steam. — It will be rioted that 
 seasoning in saturated steam necessitates a vacuum in order to 
 remove the water from the wood. With superheated steam 
 this is not necessary, as it is capable of absorbing the water 
 vapor driven .off from the wood as fast as it is formed. Some 
 of the early wood-preserving plants were equipped with super- 
 heaters, but on account of the unskilled labor generally em- 
 ployed, much timber was destroyed by being heated at too high 
 
48 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 temperatures and moreover upkeep charges were high. It was 
 largely due to such repeated losses that the use of superheated 
 steam in timber-treating plants, fell into disrepute, until its use 
 has now been practically abandoned. 
 
 Seasoning in Oil. — As with superheated steam, seasoning in 
 oil does not require a vacuum in order to remove the water from 
 the wood. After the wood is run into the treating cylinder and 
 the doors closed, creosote oil is admitted until the cylinder is 
 almost full and all the wood is submerged. Steam is then 
 passed through coils in the bottom of the cylinder and the oil 
 raised in temperature to about 220° F. This gradually vaporizes 
 the water in the wood and the water and certain oil vapors are 
 passed through condensers where the oil can be separated from 
 the water by allowing it to settle. The bath in hot oil is con- 
 tinued, until, in the opinion of the operator, most of the water 
 in the wood has been removed. Some operators continue the 
 seasoning in oil until the amount of water condensed does not 
 exceed one-sixth of a pound per cubic foot of wood per hour. 
 The cylinder is then filled with oil and the preservative injected 
 under pressure. At the present time this method of seasoning 
 is practically confined to certain plants on the Pacific Coast, 
 where it is claimed to give very good results, especially with 
 refractory woods like the Douglas fir. In addition to season- 
 ing the timber, this method also warms it for the reception of 
 the preservative. . It appears that this process may cause the 
 wood to check microscopically and hence reduce its strength. 
 This however, is discussed at length in Chapter XVIII. 
 
 Soaking Timber in Water Preparatory to Seasoning It. — If 
 freshly cut timber is soaked in water some of the soluble con- 
 stituents which it contains will be leached from the wood. The 
 wood cells will, therefore, contain a larger percentage of air space 
 so that resistance to absorption of preservative after the wood has 
 been seasoned will be decreased. In order to make this difference 
 one of any appreciable amount, it is necessary to soak the timber 
 for long periods of time. In addition to rendering the wood more 
 permeable to preservatives, it also causes the wood to season 
 with accelerated rapidity after it is removed from the water. 
 Short periods of soaking varying from 2 weeks to. 2 months are 
 productive of little or no beneficial results. This method has 
 been tried on poles and ties, and although they lost weight very 
 rapidly when first removed from the water, nevertheless they 
 
THE PREPARATION OF TIMBER 49 
 
 failed in the long run to show any appreciable decrease in weight 
 over similar timber not soaked. Furthermore, the amount of 
 preservative which they absorbed in excess of that absorbed by 
 timber unsoaked was so small (about 1/2 of 1 percent) as to be of 
 no practical value. Unless a treating plant is so situated that 
 it can afford to hold timber in storage for long periods prior to its 
 impregnation, or unless water soaking can be conducted (as in 
 rafting timber) at a very small or no extra cost, it appears that 
 water soaking as a means of preparing wood for treatment is not 
 justified by the results secured. 
 
CHAPTER V 
 PROCESSES USED IN PROTECTING WOOD FROM DECAY 
 
 Although a great many processes have been and are practised 
 in protecting timber from decay, they may be logically divided 
 into two rather distinct groups, based upon the character of the 
 protection given. These may be termed the superficial and the 
 impregnation processes. 
 
 Superficial Processes. — By superficial processes is meant those 
 processes of treatment which aim to protect the wood by simply 
 giving it a surface protection. Since in sound timber decay can 
 occur only from external attack, it is agreed that if the surface 
 of the wood is rendered resistant to the attack of wood-destroy- 
 ing fungi, the entire timber will remain sound. This contention 
 is without doubt correct, and when the surface of a timber is so 
 preserved and the surface protection is completely maintained, 
 the timber may be made to last indefinitely. Unfortunately, 
 timbers so treated are very apt to have the protective coating 
 broken, either through abrasion or checking. When this happens 
 the untreated interior is at once subject to attack, and the 
 effect of the protecting shell may be completely destroyed. In 
 this condition, the timber may be very dangerous, as it gives 
 the appearance of being sound although it may be entirely de- 
 cayed in the interior, and hence escape detection. The writer 
 has seen mine timbers painted with a preservative that appeared 
 on outward inspection to be perfectly sound, but when bored 
 into, were found to be little more than hollow columns because 
 the wood beneath the surface had entirely rotted. , Furthermore, 
 it is not always possible to detect incipient decay in wood to be 
 treated. In fact, this is often impossible without a microscopic 
 examination, which is, of course, impracticable in practice. If 
 such wood is given a superficial treatment, the incipient decay 
 in the interior is liable to continue its growth and thus the 
 soundness of the wood will eventually be destroyed. These 
 objections can be levied against all superficial processes. 
 
 On the other hand, it is often impossible to treat wood in any 
 
 50 
 
PROTECTING WOOD FROM DECAY 51 
 
 other way because of excessive cost. Superficial processes 
 are of special usefulness when only a small quantity of wood is to 
 be treated. They are cheap, easily conducted, and under 
 ordinary conditions, efficient. When the surface of the wood 
 is not subject to injury by abrasion or checking they succeed in 
 greatly prolonging the life of the wood. 
 
 Charring. — Charring is one of the oldest methods of pro- 
 tecting timber from decay that has been practised. The wood is 
 held over a fire until the outer fibers are charred. This process 
 practically surrounds the wood with a layer of charcoal which is 
 not attacked by wood-destroying fungi. The heat, furthermore, 
 destructively distills a portion of the wood and forms products 
 which may be toxic to fungi. The depth to which the wood 
 is usually charred varies from about 1/8 to 1/2 inch. Much more 
 effective results can be secured by charring seasoned wood rather 
 than green wood, as the latter will dry out on exposure and de- 
 velop surface checks, which will break the continuity of the 
 charred surface and thus expose the untreated interior. When 
 air-seasoned wood is properly charred its life is increased. The 
 treatment is very cheap and easily applied. It has a disadvantage, 
 however, in that it completely destroys the strength of the 
 outer fibers of wood and so weakens the wood. Furthermore, 
 the beneficial effects secured from it are seldom of much 
 consequence. 
 
 Brush Treatments. — ^Brush treatments are more extensively 
 practised than any other of the superficial processes. (See Plate 
 VI, Fig. B.) As the term implies, they consist in painting the 
 preservative on the surface of the wood with a brush. A large 
 variety of preservatives are applied in this manner, such as calci- 
 mine, wood preserving oils, paints, etc. Best results are secured 
 by treating only air-seasoned wood, thus avoiding danger of 
 subsequent checking. Moreover, the preservative will penetrate 
 dry wood better than green. With certain preservatives, such 
 as creosote, most beneficial results are obtained by heating them 
 to 180° or 200° F. before they arepainted onto the wood, as they 
 penetrate more deeply when applied hot. The penetration, 
 however, seldom exceeds 1/4 inch and is generally much less. 
 Brush treatments can be easily applied, are cheap and con- 
 venient. In using them care should be taken to coat all checks, 
 cracks, and joints thoroughly with the preservative. The pre- 
 servative should not be applied when the wood is frozen and 
 
52 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 wet. If an efficient preservative is used and properly applied 
 and the wood after treatment is protected from abrasion, very 
 satisfactory results can be expected. Unless these precautions 
 are exercised, the treatment may do no good whatever, but may 
 actually result in harm. Thus, unseasoned telephone poles have 
 been examined which were coated with ordinary paint and 
 which had decayed quicker than similar poles set unpainted. 
 In this case the poles checked after they were treated, allow- 
 ing fungi to enter, while the paint formed an almost imper- 
 vious coating which kept the wood moist and hence in a very 
 favorable condition for rapid decay. 
 
 Dipping.- — In view of the difficulty of working the preservative 
 into checks and cracks, dipping gives more effective results than 
 brush treating. To dip wood, however, it is necessary to have 
 some form of tank which will hold the preservative and which is 
 large enough to allow the wood to be submerged. This method 
 of treatment is particularly adapted to small products such as 
 shingles and posts. The same precautions mentioned under 
 brush treatments apply with equal force to dipping treatments. 
 On account of the greater certainty with which the entire surface 
 of the wood can be treated, dipping is safer to use than brush 
 treating and, in general, yields better results. 
 
 Impregnation Processes. — All impregnation processes aim not 
 only to protect the surface of the wood from attack but also to 
 force the preservative deeply into the wood. Thus, should the 
 surface of the wood become broken, the fibers beneath the 
 surface containing the preservative will still offer a strong 
 resistance to decay. For this reason all impregnation processes 
 are, as a rule, more efficient than superficial processes. 
 The depth to which the preservatives will penetrate depends on 
 many factors, chief of which are the kind and condition of the 
 wood, the character of the treatment, and the kind of pre- 
 servative used. Nonresistant woods like heart Douglas fir or 
 white oak may, under similar conditions, only receive asuperficial 
 treatment. 
 
 By far the largest quantity of wood treated in the United 
 States is impregnated. Impregnation processes are much more 
 expensive than superficial processes and require more or less 
 elaborate apparatus. In connection with large operations, 
 however, they are unquestionably the better ones to use and the 
 results secured by them are the best obtainable. For purposes 
 
Plate VI 
 
 Fig. a. — Sections of creosoted piling showing effect of thin strips of bark 
 adhering to the wood. (Photo through courtesy Southern R. R.) 
 
 Fig. B. — Brush treating poles. (Forest Service photo.) 
 
 (FaciTig page 52.) 
 
Plate VI 
 
 Fig. C. — An open tank plant for treating the butts of poles — California. 
 (Forest Service photo.) 
 
 Fig. D. — Wood preserving plant of the C. B. & Q. R. R., Galesburg, 111. 
 (Forest Service photo.) 
 
PROTECTING WOOD FROM DECAY 53 
 
 of discussion, impregnation processes may be divided into two 
 classes, (1) nonpressure processes, or those using no "artificial" 
 but only atmospheric pressure, and (2) pressure processes, or 
 those using "artificial" or pressures greater than atmospheric. 
 
 Nonpressure Processes. — These processes either rely upon 
 the absorptive properties of the wood for the penetration to be 
 secured, or upon the pressure of the atmosphere to force the 
 preservative into the wood. Heavy apparatus to withstand pres- 
 sures is therefore unnecessary and this fact enables plants 
 operating on this basis to be built at lower cost than those operating 
 on high pressures. This is one of the chief advantages claimed 
 for this method of treatment. The apparatus may be an open 
 vessel such as a barrel or a vat, or a cylindrical retort of metal 
 similar in form to those used in the pressure processes. For the 
 treatment of small quantities of timber, or when salts markedly 
 corrosive to iron are used, or when only a portion of the timber 
 is to be treated, the rest being left untreated, these processes 
 give very satisfactory results. As a rule the penetrations and 
 absorptions obtained with them are not as deep or as uniform as 
 those obtained in the pressure treatments, although, at times, 
 equally as good results in this respect are secured. The time 
 of treatment is also generally longer and the flexibility and con- 
 trol of the plant less than with pressure processes. 
 
 Kyanizing Process. — This process has been in use since 1832 
 when it was patented in England by John H. Kyan. It was 
 employed in the United States as early as 1840 and is claimed to 
 be the oldest method of treating timber now practised in our 
 country. The process consists in steeping timber in a solution 
 of bichloride of mercury at atmospheric temperature and pres- 
 sure. At Portsmouth, N. H., and Lowell, Mass., the treating 
 apparatus consists of solid granite tanks laid in Portland cement 
 and coated on the inside with tar applied hot. The wood to be 
 treated is piled in the tanks with laths between each layer so as 
 to allow the free circulation of the solution, which is afterward 
 pumped into the tanks. The strength of the solution is usually 
 about 1 percent. The timber is kept submerged for various 
 lengths of time but a rough estimate is to steep it 1 day plus a 
 day for each inch in thickness. Thus 2-inch plank is steeped 3 
 days, 6-inch timber 7 days, etc. The depth to which the 
 solution penetrates varies largely with the kind of wood treated 
 but ranges from about 1/10 to 1/4 inch. The extremely poison- 
 
54 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 ous nature of mercuric chloride makes it imperative to handle it 
 with caution. Its corrosive action, moreover, makes its use 
 impracticable in iroii or steel vessels unless specially prepared. 
 Like all treatments employing a water-soluble salt, it cannot be 
 used to best advantage if the timber is to be set in wet situations, 
 because the solution will leach from the wood. When the 
 treated wood is placed in fairly dry situations, very good results 
 have been reported. There is also a liability of the salt gradually 
 crystallizing on the surface of the wood where it may prove 
 dangerous to animals should they lick it. Although large quanti- 
 ties of timber have been treated by this process, its use in this 
 country has never been very extensive. This is perhaps largely 
 due to its extremely poisonous character and the comparatively 
 long time it takes to treat the wood. Cases are on record where 
 it is reported that spruce posts, Kyanized, have remained service- 
 able for over 50 years, and hemlock ties for over 13 years. 
 
 Open-tank Process. — Under this heading we will consider 
 several processes which are very similar so far as the principles 
 of treatment are concerned. They are the Seeley, Giussani, 
 and nonpressure processes. All of these processes differ in prin- 
 ciple from the Kyanizing process, in that they aim to employ the 
 pressure of the atmosphere in forcing the preservative into the 
 wood. (SeePlateVIjFig.C.) Green or air seasoned wood may be 
 used. It is first placed in a bath of hot oil and held for vari- 
 ous periods, the object being to drive a part of the air, sap, and 
 water out of the wood and thus bring the wood cells into a rarified 
 condition. The heated timber is then quickly submerged in a 
 cool preservative, whereupon a rapid contraction of the air and 
 water vapor in the wood occurs, thus "drawing in" the 
 preservative. 
 
 Professor Seeley of New York is reported the first to make 
 use of this principle on a commercial scale, he having secured 
 patents on it in 1.868. Seeley used creosote oil and claimed to 
 treat either green or seasoned wood. (See Chapter I for 
 further discussion.) 
 
 About 1898 Tomasco Giussani invented a similar process 
 in Italy which he claimed made possible the impregnation of 
 timber with dead oil of tar alone, with salt solutions alone, 
 or combinations of the two. Open tanks are used and the process 
 is a continuous one. The timber either green or seasoned is 
 carried by a conveyor to the first tank, which contains heavy 
 
PROTECTING WOOD FROM DECAY 55 
 
 creosote oil heated to about 280° F., where it is kept submerged 
 until ebullition ceases (a period of from 1 to 4 hours). 
 It is then conveyed mechanically to another open tank con- 
 taining cold creosote oil or zinc chloride or any other preserv- 
 ing salt until the desired absorption has been obtained (a period 
 of from 2 to 3 hours), after which the treatment is finished 
 and the timber is mechanically removed from the treating vats. 
 This process was demonstrated at the St. Louis Exposition in 
 1904 where it was awarded a Grand Prize. Two plants operating 
 on this process are located in Rome and Milan, Italy, but so far 
 as the author knows, it is not practised in the United States. By 
 this method of treatment deep penetrations of the preservative 
 are possible, which, in certain timbers like loblolly pine ties, 
 may extend to the center. In plants operating on this basis the 
 diffusion and absorption of the preservative cannot be as practi- 
 cally controlled as in pressure plants, but for a low initial cost of 
 installation they are efficient. 
 
 In 1904 the U. S. Bureau of Forestry (now the Forest Service) 
 conducted an extensive series of tests with what i^ called the 
 "open-tank" process at the St. Louis Exposition.^ This method 
 of treatment has since been extensively tested by the Forest 
 Service with a view to perfecting it and evolving a process which 
 could be efficiently used by the small consumer. It secured its 
 name from the character of the apparatus in which the treatments 
 are made, these being open tanks of any convenient size and shape. 
 Later experiments lead to the use of closed tanks or cylinders for 
 certain treatments and the term "nonpressure" was employed 
 to designate the process carried on in them. In principle, there- 
 fore, it differs in nowise from any of the "open-tank" processes. 
 In open-tank treatments the Forest Service recommends only the 
 use of air-seasoned wood. This is subjected to a bath in hot 
 creosote, but temperatures above 250° F. are not recommended 
 as they are liable to injure the wood. The wood is then either 
 allowed to remain in the hot oil, which is gradually cooled, or 
 else changed to a tank containing cool oil, or cool oil is pumped 
 into the tank containing the timber after the hot oil has been re- 
 moved. The process is adapted to the use of various preserva- 
 tives such as creosote, crude oil, zinc chloride, etc. Very good 
 penetrations are secured, in fact these compare favorably with 
 
 1 Circular 101, "The Open-tank Treatment of Timber," by Carl G. 
 Crawford, Washington, D. C. 
 
56 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 those secured in pressure processes. This process is admirably 
 adapted to the treatment of poles and posts where only a portion 
 of the stick is to be treated. Plants operating on this basis are 
 comparatively cheap. It is possible to control fairly accurately 
 the character of the penetration and absorption, especially in 
 woods which lend themselves readily to treatment, like sap pine. 
 For example, if a deep penetration is desired with a comparatively 
 small absorption of oil, the timber should be left in cool oil for only 
 a short period after it is removed from the hot bath. Another 
 way is to re-treat the wood after it has been treated in cool oil. 
 This tends to drive out a part of the oil in the wood provided it 
 is removed from this second hot bath while it is still hot. If 
 a heavy absorption is desired, the wood should be heated 
 thoroughly and then submerged in cool oil until the temperature 
 of the wood has reached that of the oil. 
 
 If it is desired to impregnate the wood with a water-soluble 
 salt like zinc chloride, this may be done by boiling the wood in 
 the solution (which, however, is very apt to weaken it) and then 
 allowing it to cool, or by boiling the wood in oil for a short 
 time and then submerging it in a solution of the salt. In this 
 way a deep penetration of the salt can, at times, be secured, 
 while the outer portion of the wood will have an added protection 
 due to the small amount of oil which it contains. 
 
 The length of time required to treat wood by the open tank 
 method is very variable, but a hot bath of 1 to 3 hours 
 followed by a cool bath of the same or a longer period is usually 
 sufficient. A number of open-tank plants are now in operation 
 in the United States, chiefly by farmers and mine and telephone 
 companies. 
 
 Pressure Processes. — All processes so classed rely upon the 
 use of pressures above atmospheric in order to force the pre- 
 servative into the wood. (See Plate VI, Fig. D.) In general, best 
 results are secured by such treatment, although it is by no 
 means possible to satisfactorily penetrate all woods even with 
 the use of high pressures. 
 
 Bethell {Full-cell Creosote) Process. — This process is named 
 after John Bethell who took out patents in England in 1838. 
 It 'is cominonly referred to in our country as the "full-cell 
 process." Either green or seasoned timber can be treated by 
 this process, creosote oil (dead oil of coal-tar) being the pre- 
 servative used. The timber to be treated is loaded upon steel 
 
PROTECTING WOOD FROM DECAY 67 
 
 cars or "buggies," which are run into horizontal steel cylinders 
 usually 7 feet in diameter by 132 feet long. Their length, how- 
 ever, varies from about 50 to 180 feet and diameter from 6 to 9 
 feet. If the timber is green, it is subjected to a bath of live steam 
 for several hours, after which a vacuum is drawn by means of 
 pumps. This also is held for one or more hours according to the 
 judgment of the operator. If the timber is air seasoned, the 
 steam bath is generally omitted. Creosote oil is then run or 
 pumped into the cylinder and a pressure of 100 to 180 pounds 
 applied until the gauges show the desired amount of oil has been 
 forced into the wood. The excess oil is then drained from the 
 treating cylinder and the timber is allowed to drip for a short 
 period, after which the process is ended and the charge is removed. 
 Many treating engineers draw a vacuum in the cylinder after 
 the excess oil has drained from it, as this tends to hasten the 
 drip and dry the timber. The Bethell or full-cell process is 
 considered the standard process of treating timber with creosote, 
 and the most effective results in prolonging the life of wood 
 have been secured by it. On account of the relatively large 
 amount of oil which the ties absorb, the process is, however, 
 the most expensive and for this reason several modifications 
 have been made. 
 
 Boiling Process. — This process was patented in the United 
 States by W. G. Curtis and John D. Isaacs and the patent 
 number was reissued November 1, 1895. It is used almost 
 exclusively on the Pacific Coast, largely for the treatment of 
 Douglas fir. Either green or seasoned wood can be treated, 
 although the former is at present in more extended use. The 
 wood is run into cylinders as in the Bethell process and im- 
 mersed in creosote oil heated at the start to about 160° F. A 
 space of about 10 inches is left clear from the top of the oil to 
 the top of the treating cylinder. The oil is heated by means or 
 steam coils in the bottom of the cylinder and the temperature 
 gradually raised to about 225° F. The vapors of oil and wates 
 passing over are condensed in a surface condenser. The oil if 
 kept at a temperature of about 225° F. until the rate of evapora- 
 tion does not exceed about 1/6 of a pound of water per cubic 
 foot of wood in the charge per hour; this being to drive the sap 
 and water out of the wood. The treating cylinder is then 
 filled with creosote oil at a pressure of 5 pounds per square 
 inch, the temperature falling to about 200° F. The pressure 
 
58 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 pump is then started and held at about 150 pounds per square 
 inch until the gauges show the desired amount of oil has been 
 forced into the timber. After injection, the pressure is slowly- 
 released through an overflow pipe, the excess oil drawn from the 
 cylinders, and the charge removed. In treating dry sawn 
 timber, temperatures above 214° F. and pressures over 120 
 pounds per square inch are not recommended by the advocates 
 of this process. It can thus be seen that the boiling process 
 resembles the Bethell process except for the preliminary treat- 
 ment which the timber is given. 
 
 The Buehler Process. — ^Walter Buehler secured two patents 
 in the United States on September 22, 1908 (Nos. 899237 and 
 899480) on the process which bears his name. Either green 
 or seasoned timber can be treated, the preservative being 
 creosote oil. The process is not at present in extended use. 
 Green or water-soaked timber is treated as follows. It is run 
 into the treating cylinder as in the Bethell process and im- 
 mersed in creosote heated to a temperature of not less than 
 140° F., the cyhnder being completely filled with oil. The 
 temperature of the oil in the cylinder is kept gradually rising 
 as fast as the condensation will permit until it reaches between 
 220° and 260° F. It is then held to maintain a regular and 
 constant temperature within the cylinder. During this season- 
 ing period the gauge on the cylinder should show a pressure of 
 not more than 5 pounds. The maximum temperature is 
 maintained until the condensation in the hot well shows the 
 interior of the wood "to be sufficiently dry," when the steam 
 in the coils is released and the cylinder filled with creosote, the 
 temperature being lowered to about 200° F., when the pressure 
 pump is started and the oil is forced into the wood until the 
 desired amount has been absorbed. The cylinder is then 
 drained of excess oil and an air pressure of 15 to 25 pounds per 
 square inch is applied and held to penetrate all of the wood. 
 This completes the process. 
 
 For air-seasoned timber, a vacuum of at least 20 inches is 
 drawn after the wood is placed in the cylinder, and held for at 
 least 20 minutes. Creosote is then admitted and pressure ap- 
 plied with the force pump until the proper amount of oil has 
 been injected. The excess oil is then drained from the cylinder 
 and an air pressure of 15 to 25 pounds is maintained until the 
 
PROTECTING WOOD FROM DECAY 59 
 
 maximum pressure remains constant for at least 15 minutes, after 
 which the treated timber is removed from the cylinder. 
 
 Tests made by the author showed that air pressures applied 
 to wood freshly impregnated with creosote forced much of the 
 creosote out of the wood after these pressures were released and 
 greatly prolonged the time it took the timber to drip. 
 
 The A. C. W. Process. — In the A. C. W. process, so called 
 after the American Creosote Works in Louisiana in which it is 
 practised, after the timber has been subjected to a preliminary 
 seasoning of live steam, and after a vacuum has been drawn, air 
 is forced into the cylinder until a pressure of about 15 pounds is 
 obtained. Creosote is then admitted, the air pressure being 
 still maintained to prevent excessive or unequal absorption of 
 the oil while the cylinder is being filled. The surplus air is al- 
 lowed to escape through a pop valve at the top of the cylinder. 
 When the cylinder is full of oil a pressure of 100 pounds or more is 
 applied with a pump until the proper amount of the creosote has 
 been forced into the timber. The oil is then run from the treating 
 cylinder and an air pressure of 60 to 80 pounds applied. This 
 is introduced to drive the oil into the wood to a greater depth 
 and to secure greater uniformity of treatment. 
 
 The process is not in general use and is practically confined to 
 the plant operated by the American Creosote Works. 
 
 The Lowry Process. — This process is covered in the United 
 States by Patent No. 831450, issued to C. B. Lowry under date of 
 September 18, 1906. 
 
 Air-seasoned timber is loaded on tram cars and placed within 
 the treating cylinder. The cylinder is then filled from the 
 charging tank with creosote oil at a temperature not to ex- 
 ceed 200° F. The main line is then closed and oil from the 
 charging tank is forced by pressure pumps into the retort 
 until the timber has taken oil to the point of refusal, or a 
 predetermined amount. The pressure and temperature within 
 the retort are controlled so as to give a maximum penetration 
 of the oil. The pressure is then released and the free oil in 
 the retort is drained off. A vacuum of sufficient degree and 
 duration is then drawn in the retort to recover that portion 
 of the free oil in the timber above the specified amount. The 
 recovered oil is then drained off from the retort and the charge 
 is withdrawn. The Lowry process may be termed an "empty- 
 cell" process in that it aims to secure a deep penetration of 
 
60 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 creosote without consuming as much of it as the Bethell or full- 
 cell process. At the present time the process is in very extended 
 use in the United States, particularly in treating cross-ties, eleven 
 plants now operating under its patent. 
 
 Rue-ping Process. — This is also termed an "empty-cell" 
 process in that the object sought is a deep penetration of creosote 
 with a comparatively small consumption of the oil. It was 
 patented in the United States on September 23, 1902, the issue 
 being to Messrs. Halsberg & Co., M. B. H., of Germany. The 
 timber to be treated should preferably be air-seasoned. Green 
 or partially seasoned wood is subjected to a steam and vacuum 
 bath similar to that given in the Bethell process before the treat- 
 ment is begun. After the timber has been placed in the treating 
 cylinder, compressed air is admitted frequently from an overhead 
 tank and held until the wood is filled with compressed air. Creo- 
 sote is then admitted under a slightly higher pressure, the air in 
 the cylinder gradually escaping. When the cylinder is filled 
 with creosote the pressure on the oil is raised to about 150 or 
 more pounds and held until no more oil can be forced into the 
 wood. The cylinder is than drained of oil and a final vacuum 
 drawn to increase the expansive force of the air in the timber and 
 to dry the wood as quickly as possible. The length of time the 
 compressed air is held, the pressure of the compressed air, the 
 length and pressure of the oil period, and the length of the final 
 vacuum all vary with the kind of timber under treatment. 
 When they are properly adjusted, penetrations as deep as those 
 secured in the Bethell process are obtained, in some cases with 
 one-half or less the consumption of oil. Rueping-treated timber 
 has a tendency to drip much longer than timber treated without 
 the use of compressed air, and the rate of evaporation of the 
 creosote from it is also likely to be greater. The process is now 
 in extended use in both the United States and Europe. 
 
 Burnett Process. — William Burnett patented this method of 
 treatment in England in 1838 and it has been in constant use 
 since. It is commonly referrred to as the standard process 
 using a water-soluble salt, chloride of zinc. The method of 
 treatment is exactly analogous to the Bethell process, the only 
 essential difference being in the character of the preservative. 
 As a general rule, water solutions can be forced into wood deeper 
 than oils, so that under any given set of conditions slightly better 
 penetrations are secured from the use of zinc chloride than from 
 
PROTECTING WOOD FROM DECAY 61 
 
 creosote. The Burnett treatment is in extensive use in the 
 United Statels and Europe, where it has given excellent results 
 in prolonging the life of timber not set in very wet conditions. 
 On account of the soluble nature of the salt, several methods 
 have been employed to retard its leaching action, some of which 
 are now extensively practised. 
 
 Rutgers Process. — The objections of the comparatively high 
 cost of creosote and the leachability of zinc chloride are both 
 partially overcome by the Rutgers process, invented by Julius 
 Rutgers in Germany about 1874. Rutgers handles the timber to 
 be treated in much the same way as is done in the Bethell pro- 
 cess, but employs a mixture of zinc chloride and creosote as his 
 preservative. The zinc chloride is generally in a 3 to 5 percent 
 solution and comprises about 80 percent of the mixture. To this 
 a comparatively low-gravity creosote free from naphthalene is 
 added by means of a jet of steam or air or other suitable mixing 
 device. The timber thus treated contains both creosote and zinc 
 chloride injected simultaneously. While the process is not 
 practised in the United States, it has found extensive use in 
 Germany, where it is reported to give marked satisfaction, 
 particularly in the treatment of cross-ties. 
 
 CardProcess. — The principle of injecting timber simultaneously 
 with zinc chloride and creosote was adopted by J. B. Card, to 
 whom a patent was granted in the United States on March 20, 
 1906. Card's process differs essentially from that of Rutgers in 
 the manner of keeping the solution mixed. He uses about 80 per- 
 cent of zinc solution to 20 percent of creosote, the strength of 
 the zinc being regulated so that approximately 1/2 pound of the 
 dry salt will be injected with each cubic foot of wood treated. 
 This solution is first mixed in the measuring tank by forcing air 
 through perforated pipes placed on the bottom. When the 
 solution is run into the treating cylinder, thie agitation is continued 
 by means of a centrifugal pump which draws it from the top of the 
 retort and returns it through a perforated pipe running length- 
 wise in the bottom of the cylinder. The steps in the Card proc- 
 ess are analogous to those in the Bethell process. Air-seasoned 
 timber is advocated. After this is run into the cylinder a vacuum 
 of 22 to 26 inches is drawn for about 1 hour. The preservative 
 mixture is then admitted at a temperature of about 180° F. and a 
 pressure of about 125 pounds per square inch applied to it by 
 means of force pumps for 3 to 5 hours, or until the desired 
 
62 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 absorptions have been secured. During this period, the centrif- 
 ugal pump is kept running in the manner described above, to 
 agitate the solution in the cylinder. The cylinder is then drained 
 of excess preservative and a final vacuum drawn to assist in dry- 
 ing the timber, after which the charge is removed. DiflElculty 
 may be experienced in keeping the solution uniform during treat- 
 ment, unless the proper conditions are maintained. Good 
 penetrations of both creosote and zinc chloride are secured in this 
 process, which is now extensively used in the United States, 
 particularly for the treatment of cross-ties. 
 
 Wellhouse Process. — Experience with the Wellhouse or zinc-tan- 
 nin process began about 1881, when some ties were treated in St. 
 Louis, Mo. In the early 80's and 90's this method of treatment 
 was extensively used in the United States but at the present time 
 the amount of timber treated by it is comparatively small. The 
 chief objections to its use were apparently the many manipula- 
 tions required and the difficulty of satisfactorily operating them. 
 
 The timber to be treated is handled much the same as in 
 the Burnett process except for the manipulations of forcing the 
 preservative into the timber. After the timber has been placed 
 in the treating cylinder and seasoned, as in Burnettizing, a so- 
 lution of zinc chloride and glue in the proportions of 1 1/2 to 3 
 percent of the former to one-half of 1 percent of the latter 
 is forced into the wood by means of pressure pumps under a 
 pressure of about 125 pounds per square inch and held for 3 to 6 
 hours. The excess preservative is then drained from the cylinder 
 and a water solution of one-half of 1 percent tannin is introduced 
 and forced into the timber at 125 pounds pressure for about 2 
 hours, after which the excess tannin solution is drained from 
 the cylinder and the charge removed. The tannin combines with 
 the glue and forms a "leathery substance" which tends to plug up 
 the pores of the wood and retard the zinc chloride from leaching 
 out. The process was later modified by injecting the glue sepa- 
 rately, it being found that it retarded the entrance of the zinc 
 solution. The temperature of the treating solution as well as 
 the strength of the zinc chloride used was also raised. 
 
 While the mixture of glue and tannin does tend to plug the 
 wood cells, nevertheless, the extent to which they do this has 
 been exaggerated. The zinc-chloride solution not only resists 
 the entrance of the glue and tannin in subsequent injection, but 
 the air confined in the wood tends to push the plug out of the 
 
PROTECTING WOOD FROM DECAY 63 
 
 cells due to its expansive force. Microscopic examinations of 
 Wellhouse-treated wood have shown that the "plug" is only a 
 surface coating and seldom actually extends into the timber. 
 While very good results have been secured from this method of 
 treatment, it is believed that better results could have -been ob- 
 tained if a strong preliminary vacuum had been drawn and held 
 while the zinc solution was entering the cylinder. The Well- 
 house process is comparatively cheap, costing about 18 cents per 
 tie, and has succeeded in more than doubling the life of ties which 
 like hemlock, red oak, and gum decay very rapidly. 
 
 Allardyce Process. — So called after R. L. Allardyce, who sug- 
 gested its use. The timber to be treated is handled much as in the 
 Wellhouse process except that creosote instead of glue and tannin 
 is used. A 4 percent zinc-chloride solution is forced into the 
 wood at a pressure of about 130 pounds per square inch, after 
 which the cylinder is drained and refilled with creosote, this be- 
 ing injected under a pressure of about 180 pounds per square inch 
 so as to form a continuous outer layer around the zinc-treated 
 timber. As might be expected, the penetration of the creosote is 
 slight. If, however, the timber is removed from the cylinder after 
 its injection with zinc chloride and allowed to air season, and then 
 re-treated with creosote, better results are obtained. The delay 
 thus occasioned and the increased cost of handling then become 
 serious objections. The Allardyce process is not in extensive 
 use at this time. 
 
 The author treated a number of red oak and maple ties by 
 reversing the Allardyce method. These were first impregnated 
 with 2 to 3 pounds of creosote per cubic foot, after which 
 the cylinder was drained and refilled with a 3 percent zinc- 
 chloride solution forced into the wood until 1/2 pound of the 
 dry salt was injected. The cylinder was drained and the 
 charge removed. The results secured were very similar to those 
 obtained in the Card process, much of the creosote being carried 
 further into the wood. By this manipulation, delay in treating 
 and increased cost of handling are avoided, but unless extreme 
 care is exercised. the zinc-chloride solution will soon become 
 contaminated with the creosote, so that the amount of each con- 
 sumed will become a matter of speculation. 
 
CHAPTER VI 
 
 PRESERVATIVES USED IN PROTECTING WOOD FROM 
 
 DECAY 
 
 Properties of Efficient Preservatives. — Hundreds of chemicals 
 and compounds have been advocated and tested to preserve 
 wood from decay, but only a few of them possess sufficient 
 merit to justify their use for this purpose. As was shown in 
 Chapter II, decay in timber is caused by fungi and bacteria. 
 To preserve wood from decay it is therefore absolutely essential 
 to protect it from the attacks of these organisms. In brief, all 
 fungi and bacteria which decay wood require certain amounts 
 of heat, air, moisture, and food in order to live. If one or mose 
 of these essentials can be eliminated, these organisms cannot 
 live and hence wood will remain sound indefinitely. The basic 
 problem, therefore, in any efficient preservative process is to ac- 
 complish this. Obviously a control of heat and air around struc- 
 tural timber set subject to decay is exceedingly difficult and 
 generally impracticable. Hence a control of the moisture in 
 the wood and the food of the fungus (which is the wood sub- 
 stance) are the two most practical lines of preventing attack. 
 Wood kept constantly under water is too wet to permit the fungi 
 to grow and hence will remain sound ad infinitum. Conversely, 
 wood kept constantly air dry or drier contains too little moisture 
 for fungous growth and will never decay — to wit, the durability 
 of furniture in dwellings, etc. All successful wood preservatives, 
 therefore, either keep the wood comparatively dry or else poison 
 the wood so that the organisms attacking it are killed. 
 
 The amount of moisture in wood necessary for the growth of 
 wood-destroying fungi is not definitely known. It is the author's 
 opinion that in general it must be not less than 20 percent. 
 Certain fungi which have the ability of making or transporting 
 moisture may be able to attack wood containing a smaller 
 moisture content than this. It is well known that posts set in 
 the ground decay in or near the ground and rarely in the top. 
 To secure some data on the distribution of moisture in posts, 
 the author placed several cedar posts in the ground and took 
 
 64 
 
PRESERVATIVES USED IN PROTECTING WOOD 65 
 
 moisture borings 2 inches deep 2 feet below ground level, 
 at ground level, and 3 feet above ground level, at various 
 periods extending over a year. That portion of the posts buried 
 in the ground contained in general about 30 percent moisture, 
 that near the ground line about 32 percent, and that near the 
 top less than 17 percent. If, then, wood can be impregnated 
 or coated with a substance that will keep it comparatively dry, 
 the fungi and bacteria will be unable to develop and the wood 
 will remain sound. This is the basic principle involved in the 
 use of nontoxic oils, like petroleum. 
 
 In general, most effective results in prolonging the life of timber 
 from decay are obtained by using some chemical which is toxic 
 and which thus poisons the food of the fungus. . Toxic preserva- 
 tives differ considerably in their effectiveness against fungi. 
 Considerable work has been done by a number of investigators 
 to determine the smallest amount of preservative necessary to 
 inhibit fungous growth. This is called the "toxic limit." One 
 of the most satisfactory methods of doing this is by means of 
 cultures in glass dishes by what is known as the "petri-dish 
 method." It consists, in brief, in pouring into the sterilized 
 petri-dishes a solution of agar-agar of the following approximate 
 composition: Juice from 1 pound of beef, 25 grams of Loff- 
 lund's malt extract, 20 grams of agar-agar, and 1000 c.c. of dis- 
 tilled water. Upon this medium is placed a small mat of fungus 
 mycelium. The dish thus inoculated is placed in a constant 
 temperature oven for about 6 weeks. Various amounts of the 
 preservative to be tested are weighed on a chemical balance and 
 mixed into the culture medium. The fungus will grow readily 
 on low concentrations but a concentration is finally reached 
 above which no growth occurs. The smallest concentration 
 which inhibits growth is called the "toxic limit" or "toxicity" 
 of the preservative. A number of preservatives have been 
 tested in this manner by C. J. Humphrey at the U. S. Forest 
 Products Laboratory, the results being given in Table 4 
 The greater the toxicity of a preservative, the greater is its 
 ability to kill fungi and keep wood sound. It frequently happens, 
 however, that those preservatives which are most toxic are not the 
 ones which give best satisfaction in prolonging the life of wood, 
 because they may have certain inherent characteristics' which 
 vitiate or preclude their use. Chief among these are their 
 permanency, and corrosion of iron, 
 s 
 
66 
 
 THE PRESERVATION OF STRUCTURAL TIMBER 
 
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PRESERVATIVES USED IN PROTECTING WOOD 
 
 67 
 
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 and will, if exposed to ordinary atmospheric conditions, leach 
 out of wood. If they should do this at a rapid rate, the wood 
 will soon be left unprotected so that the fungi can attack it. 
 In order to be effective, therefore, such preservatives must 
 remain in the wood for long periods. 
 
 While organic preservatives are, as a rule, insoluble in water 
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 70 
 
 SO 
 
 Fig. 5. — Comparative rates at which fractions of coal-tar creosote evaporate 
 from wood. (Cir. 188, U. S. Forest Service.) 
 
 that the amount remaining in the treated timber may eventually 
 become so small as to be ineffective in further protecting the 
 wood from decay. This is particularly true of the lighter 
 fractions of coal-tar creosote, as is shown in Fig. 5, which 
 represents the rate at which various fractions of coal-tar creosote 
 and creosote evaporated from sap loblolly pine sticks 6 inches in 
 diameter and 24 inches long impregnated with about 18 pounds 
 
68 
 
 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 each of oil and later exposed to the atmosphere. ^ in this figure the 
 temperature represents the limits between which the distillates 
 were obtained from the creosote. The permanency of the 
 higher boiling fractions is well shown. Other tests^ made on 
 timbers subjected to service for 20 or more years also show that 
 the higher boiling constituents are the most permanent. 
 
 Table 5. — CoRROsrvE Action op the PRESERVAxrvE' 
 
 Preservatives designated by mamifac- 
 
 turer as 
 
 Loss in weight (grams) of flange steel after 
 immersion in preservative at 98° C. for 
 
 3 weeks 
 
 4 weeks 
 
 Ooal-tar creosote 
 
 0.0064 
 0.0000 
 0.0389 
 0.0063 
 0.0313 
 0.0005 
 0.0807 
 8.2629 
 5.0989 
 1.2938 
 0.0243 
 0.2222 
 0.0096 
 0.0012 
 1.4636 
 0.6050 
 1.3809 
 3.1660 
 0.1256 
 0.0139 
 
 
 
 0.0008 
 0.0401 
 0.0467 
 0.0296 
 0.0015 
 0.0951 
 11.2350 
 
 Coal-tar creosote Frac. 2 
 
 Coal-tar creosote Frac. 3 
 
 Coal-tar creosote Frac. 4 
 
 
 
 Wood creosote (Douglas fir) 
 
 1.5029 
 
 1 07 oil 
 
 
 
 CoDDerized oil 
 
 
 Fuel oil 
 
 0.0062 
 
 
 
 
 Zinc sulphate (&) by-product. . . . 
 
 
 4.1746 
 0.1588 
 0.0181 
 
 Sodium fluoride 
 
 Cresol calcium 
 
 (a) Equivalent to 2. 1 percent 
 (6) Equivalent to 6.2 percent 
 
 zinc-chloride solution, 
 zinc-chloride solution. 
 
 As nearly all wood preserving plants are built of steel cylinders, 
 any preservative which attacks steel cannot, of course, be used in 
 them. This excludes such preservatives as mercuric chloride, 
 copper sulphate, etc., from standard practice. A number of 
 tests were run at the U. S. Forest Products Laboratory to de- 
 termine the corrosive action on steel of various wood preserva- 
 tives. A strip of flange steel of the quality specified by the 
 
 1 Circular 188, U. S. Forest Service, by C. H. Teesdale. The Volatili- 
 zation of Various Fractions of Creosote after Their Injection into Wood. 
 
 " See circulars 98 and 199, U. S. Forest Service. 
 
 ' "Tests to Determine the Commercial Value of Wood Preservatives," 
 by H. F. Weiss, Eighth International Congress of Applied Chemistry. 
 
PRESERVATIVES USED IN PROTECTING WOOD 69 
 
 American Society for Testing Materials, August 16, 1909, was 
 submerged in the preservative and heated to a constant tem- 
 perature of about 98° C. The preservative was changed every 
 week for four weeks in the case of oils; with aqueous solutions it 
 was changed every day for one week. The difference in the 
 weight of the steel before and after submersion was taken to 
 indicate its corrosion. All depositions on the surface of the 
 metal were removed as nearly as possible with a rubber " police- 
 man" each time the preservative was changed. At the end of 
 the test, where electrolytic deposition of metal had taken place, 
 the deposited metal was removed by acid and its amount 
 determined by an analysis of the acid solution. The deposited 
 metal thus obtained was added to the loss of iron and this total 
 represented the total corrosion. The corrosive action of the 
 various preservatives tested is shown in Table 5. 
 
 The odor of the preservative sometimes influences its use, 
 particularly if the wood is to be placed in dwellings. All inorganic 
 preservatives are practically odorless and hence not objectionable 
 on this account. Many of the organic preservatives, particularly 
 the "creosotes" from wood, coal, and petroleum, have strong 
 odors which are quite offensive. If allowed to air season thor- 
 oughly before being placed in position much of the odor can be 
 removed. 
 
 It frequently happens that it is desirable to paint wood arti- 
 ficially preserved. This is particularly the case with wood used 
 in dwellings, greenhouses, etc. Creosoted timber cannot be 
 painted satisfactorily with any of the lighter pigments, but 
 practically all of the salts are free from this objection. Two 
 other factors of practical significance in determining the 
 value of a chemical for wood preserving purposes are the effect 
 the preservative has on the strength of the wood treated with it, 
 and the ability of the preservative to penetrate the wood. If the 
 preservative is such as to seriously impair the strength of wood 
 treated with it, it will necessitate the use of larger timbers and 
 hence increase the cost of the structure. Moreover, if the 
 preservative is of such a nature that it cannot be forced into 
 wood, its value is considerably decreased on this account, because 
 it will succeed in only protecting the surface of the wood. Any 
 injury to the surface will therefore result in exposing the un- 
 treated interior. Tests to secure data on both these points were 
 conducted at the U. S. Forest Products Laboratory on air- 
 
70 
 
 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 seasoned hemlock. Approximately 8 pounds of the preservative 
 per cubic foot in the case of oils and 1/2 pound or more of 
 the dry salt in the case of water solutions were forced into the 
 wood by the Bethell process. The wood was then permitted 
 to air season and tested in bending on a 30,000-pound testing 
 machine, the strength of the treated pieces being compared with 
 that of the untreated. In the penetrance tests the preservative 
 was forced into a hole bored into the wood under a constant tem- 
 perature of 180° F. and pressure of 80 pounds per square inch for 
 30 minutes when oils were used and 3 minutes for salt solutions. 
 The sticks were then sawed and the depth to which the preserva- 
 tives entered was measured. The results of both these tests are 
 shown in table 6. 
 
 Table 6. — Penetrance op the Pbesbrvatives and their Effect on 
 THE Strength op Wood 
 
 Preservative 
 
 designed by 
 
 manufacturer as 
 
 Penetration 
 
 Had. and 
 
 tang. 
 
 Max. Min 
 
 Longi 
 
 Max. Min. 
 
 <D rt ^ 
 9%t 
 
 M M 
 
 P.-3 o § 
 
 .rt o ^* 
 MI'S 3 rt 
 
 Moisture 
 at test. 
 
 Coal-tar creosote 
 
 S.P.F. carbolineum . . . 
 
 Avenarius Carbolin- 
 eum 
 
 Hardwood tar 
 
 Creosote (Douglas fir) 
 
 1.07 oil 
 
 Timberasphalt 
 
 Copperized oil 
 
 Zinc chloride 
 
 Zinc sulphate (by- 
 product 
 
 Zinc sulphate 
 
 Creosol calcium 
 
 B.M. preservative. . . . 
 
 Sodium silicate 
 
 Sodium fiuoride 
 
 In. 
 
 0.28 
 0.37 
 
 0.02 
 0.22 
 0.10 
 
 0.25 
 0.10 
 0.10 
 0.13 
 0.05 
 0.10 
 
 In. 
 
 0.23 
 0.23 
 
 0.12 
 0.03 
 0.08 
 0.10 
 0.02 
 0.22 
 0.083 
 
 0.17 
 0.08 
 0.10 
 0.10 
 0.03 
 0.10 
 
 In. 
 
 6.0 
 6.0 
 
 6.0 
 
 0.92 
 
 3.58 
 
 6.0 
 
 0.33 
 
 6.0 
 
 6.0 
 
 6.0 
 
 6.0 
 
 6.0 
 
 6.0 
 
 0.46 
 
 6.0 
 
 ■ In. 
 
 5.3 
 
 5.7-f 
 
 5.3 + 
 
 O.SO 
 
 2.33 
 
 3.33 
 
 0.33 
 
 4.08 
 
 5.3 
 
 4.66 
 
 4.66 
 
 3.30 
 
 4.6 
 
 0.30 
 
 5.00 
 
 Lb. per 
 cu. ft. 
 8.76 
 8.83 
 
 8.08 
 6.50 
 2.82 
 9.58 
 5.68 
 8.58 
 0.432 
 
 1.11 
 0.96 
 0.46 
 0.50 
 0.99 
 0.20 
 
 93 
 
 6.2 
 
 109 
 98 
 107 
 108 
 106 
 101 
 88 
 
 82 
 89 
 103 
 85 
 82 
 85 
 
 6.81 
 
 6.11 
 
 5.8 
 
 4.52 
 
 6.68 
 
 5.49 
 
 7.13 
 
 5.14 
 5.72 
 5.16| 
 6.42 
 5.82! 
 
 9.35 
 
 5.77 
 
 9.6 
 
 6.58 
 
 9.48 
 
 7.38 
 
 8.7 
 
 1 A penetration of 6 inches was the maximum that could be secured. The absorptions 
 here given have no reference to the data on penetrance. 
 
 2 Dry salt. 
 
 The effect of the preservative in the wood upon the inflamma- 
 bility of the wood is also an important consideration, particularly 
 in mines, bridges, and dwellings. This effect is described at 
 length in Chapter XVI. 
 
 It can be seen from this discussion that many factors aside from 
 cost, ease of transporting, etc., affect the practical value of a 
 
PRESERVATIVES USED IN PROTECTING WOOD 71 
 
 preservative, and that no one preservative possesses all the re- 
 quirements which will make its use applicable to all conditions. 
 A selection is therefore imperative. 
 
 The preservatives which have most conspicuously succeeded 
 in fulfilling the above requirements may be logically grouped into 
 three classes, (1) water-soluble preservatives, (2) crude oils, and 
 (3) creosotes. 
 
 Water-soluble Preservatives. — While a large number of water- 
 soluble preservatives have been tested, only a few have proven 
 of any practical value. Most of them are either not sufficiently 
 toxic against fungi or form reactions with the wood which tend 
 to destroy the strength of the wood. This latter is particularly 
 the case with iron sulphate and chemicals strongly alkaline. Of 
 the many water-soluble preservatives tested, copper sulphate, 
 mercuric chloride, sodium flouride, and zinc chloride have given 
 best results. 
 
 Copper Sulphate. — This salt was first put to extensive use by 
 , Margary in England about 1837. It was later used by Boucherie 
 in France, where it is still commonly employed in treating timber, 
 particularly poles. It is strongly toxic against wood-destroying 
 fungi. It is readily soluble in water and easily leaches from wood 
 treated with it. The chief objection to its use is its action on 
 iron, the copper being immediately deposited. It cannot, on 
 this account, be used in the standard type of timber-preserving 
 plant. It is comparatively cheap, costing about 5 to 6 cents per 
 pound, and when injected into wood gives good results. It is 
 almost as eflacient as zinc chloride, poles treated with it in 
 Germany lasting 11.7 years as compared with similar poles treat 
 ed with zinc chloride which lasted 11.9 years. One desirable 
 quality is the ease with which the preservative can be seen in the 
 wood, as it stains the wood cells a distinct green. The use of this 
 salt is now practically confined to France. The amount of timber 
 treated with it in the United States is insignificant. It is believed, 
 however, to have distinct merit, particularly for the treatment of 
 green posts and poles. (See Boucherie process for further 
 discussion.) 
 
 Mercuric Chloride. — This is the most toxic wood preservative 
 in use. It was first extensively employed by Kyan in England 
 about 1832. Extremely small quantites of this salt in wood 
 will absolutely kill all wood-destroying fungi. Its toxic limit is 
 even below that of such toxic salts and acids as potassium di- 
 
72 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 chromate, silver nitrate, hydrochloric acid, etc. It cannot be 
 safely tested with agar in petri dishes since it unites with the pro- 
 teid elements of the agar. 
 
 Magnin and Sternberg^ conducted extensive tests with various 
 antiseptics upon the septic micrococcus, with the following 
 results : 
 
 Corrosive sublimate 1 part in 40,000 prevented development. 
 
 Copper sulphate 1 part in 400 prevented development. 
 
 Zinc chloride 1 part in 200 prevented development. 
 
 Carbolic acid 1 part in 300 prevented development. 
 
 Mercuric chloride is much less soluble in water than zinc 
 chloride or copper sulphate. It, unfortunately, severely attacks 
 iron, hence its use is debarred in modern treating plants. Al- 
 though it is expensive, costing about 70 cents a pound, neverthe- 
 less the~very small quantity necessary to keep wood sound does 
 not by any means render its use prohibitive. On account of its 
 very poisonous nature, solutions of mercuric chloride must be 
 handled with extreme care or mercurial poisoning will result. 
 This salt is not in extended use at the present time in this country 
 but is employed by a few'Kyanizing works in New England. In 
 India and Africa it is reported as giving very good results against 
 the attacks of white ants. Poles treated with it in Germany 
 lasted 13.7 years as against 11.9 years for zinc-treated poles. 
 
 Sodium Fluoride. — ^The commercial application of sodium 
 fluoride to the preservative treatment of timber is comparatively 
 recent. It has been tested by Malenkovic in Austria for the 
 past 8 years with apparently excellent results. It is more 
 toxic than zinc chloride (see Table 4) and is not so readily leached 
 from the wood. Its corrosive action on iron is also slight, being 
 less than that for zinc chloride, so that it can be used in modern 
 timber -treating plants. Its cost is also comparatively low, being 
 about 5 to 7 cents per pound. No records are known 
 showing the use of sodium fluoride as a wood preservative in the 
 United States. Extensive experiments, which have thus far 
 yielded very satisfactory results, are now under way at the 
 U. S. Forest Products Laboratory and it is quite likely that this 
 salt may find a large commercial application in this country. 
 
 Zinc Chloride. — About 20,000,000 pounds of zinc chloride are 
 now used annually in the United States in treating timber — an 
 amount which makes it by far the most extensively used water- 
 
 ' Boulton — The Preservation of Timber, 1885. 
 
PRESERVATIVES USED IN PROTECTING WOOD 73 
 
 soluble salt. It was first employed on an extensive scale by Sir 
 William Burnett in England about 1838 and timber is now 
 treated with it in all the larger European countries. Zinc chloride 
 is very toxic against wood-destroying fungi, offering about the 
 same resistance as coal-tar creosote. Its chief fault is its solu- 
 bility in water, which property renders it inadvisable to use 
 zinc-treated timbers in wet localities. In localities which are 
 not excessively wet, the zinc chloride will remain in the timber for 
 many years. Numerous cases are on record which show zinc- 
 treated ties have remained durable for 10 or more years, while 
 the untreated failed in 4 to 5 years. It appears from various 
 analyses which have been made that certain amounts of zinc 
 chloride injected into wood combine with the wood forming a 
 compound insoluble in water. Whether or not this combined 
 zinc chloride is toxic has not yet been definitely determined. 
 If it is not, it probably is of little or no value in preserving the 
 wood. 
 
 Zinc chloride will also corrode iron, although the extent to 
 which it does this at concentrations used in treating wood is so 
 small as to be of no serious moment. It is customary, however, 
 to figure higher depreciation on zinc-chloride plants than on 
 creosote plants due to its more corrosive nature. 
 
 The cost of zinc chloride is small, being about 4 or 5 cents a 
 pound. Moreover, the quaUty generally produced in this 
 country is of very high grade, far superior to that commonly pro- 
 duced abroad. Zinc chloride is purchased fused in drums of 600- 
 or lOOO-pound capacity, or in concentrated (about 50 percent) 
 solution. When in high concentration the solution is basic and 
 will strongly attack wood, reducing it to a pulp. At dilute con- 
 centrations the solution is acid. 
 
 Owing to its importance as a wood preservative, the following 
 specification for the purchase of zinc chloride is given. It is 
 the one used by the U. S. Forest Products Laboratory. A 
 similar specification is in use by the American Railway Engineer- 
 ing Association. 
 
 "The fused zinc chloride must contain at least 94 percent of water- 
 soluble chloride of zinc and it must be slightly basic; that is, contain no 
 free acids. It should be practically free from soluble iron and in no case 
 will it have more than 0.022 percent of this element. It shall not con- 
 tain more than one-haK of 1 percent of other inorganic impurities in- 
 soluble in hydrochloric acid." 
 
74 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 Although several methods have been suggested for determining 
 the amount of zinc chloride injected into wood, the following is 
 believed to be the most accurate and satisfactory.^ 
 
 The material to be analyzed is first dried in the form of discs or sec- 
 tions and should be a fair average. The discs are then reduced to saw- 
 dust and 5 grams are weighed into a 500 c.c. short-neck, round-bottom 
 Jena boiling flask: 50 c.c. of a previously prepared saturated solution of 
 potassium chlorate in concentrated nitric acid is then added in the cold 
 and mixed into it by a vigorous shake. A violent reaction, accompanied 
 by the evolution of considerable heat, immediately takes place but sub- 
 sides after a few minutes leaving a wine-colored solution in which parti- 
 cles of partly digested wood are floating. When cool, 10 c.c. of concen- 
 trated sulphuric acid (sp. gr. 1.8) are added and the solution again shaken. 
 This dissolves aU the wood substance. The solution is then boiled. 
 More potassium chlorate-nitric acid solution is added and the solution 
 kept boiling until no further charring occurs on evaporation to sulphuric 
 acid and the solution remains a pale yellow. When cool, it is diluted 
 with 100 c.c. of water; 10 c.c. of dilute nitric, 10 c.c. of 2 percent ferric 
 chloride solution, and 1 gram of citric acid are then added, and the solu- 
 tion again allowed to cool. After cooling it is neutraUzed with ammo- 
 nia leaving it slightly ammoniacal. The volume is brought up to 200 
 c.c. and the temperature to 80° C. at titration. The standard solution of 
 potassium ferrocyanide is then run in from the burette until a drop of 
 the titrated solution when placed in the center of 1 c.c. of the glycerine 
 acetic acid indicator leaves a permanent greenish-blue ring. At this 
 point the titration is complete. Calculations are then made from the 
 analytical data. To calculate the results in pounds of zinc chloride per 
 cubic foot of wood, the specific gravity of the wood must be known to • 
 within 0.005. Then multiply this specific gravity to 62.5 and this prod- 
 uct by the percentage weight of zinc chloride found by analysis to 
 obtain the amount of zinc chloride per cubic foot of wood. 
 
 If knowledge of the actual amount of zinc is not desired, but 
 simply an idea of how deeply it has penetrated, two methods are 
 suggested. One is to cut a section through the stick to be ex- 
 amined and dry it thoroughly in a drying oven heated to 100° C. 
 until all water has been evaporated. The wood will be turned a 
 deep brown wherever the zinc chloride has penetrated. A 
 second method is to dip the freshly cut disc of treated wood for a 
 few seconds in a 1 percent potassium ferrocyanide solution. 
 Remove the excess solution with a blotting paper and redip the 
 disc into a 1 percent solution of uranium acetate. On drying, 
 
 1 Method developed by Bateman, U. S. Forest Products Laboratory. 
 
PRESERVATIVES USED IN PROTECTING WOOD 75 
 
 the untreated portion of the wood will have a dark red color while 
 the treated portion will be much lighter. 
 
 Crude Oils. — Crude oils are not widely used in treating timber 
 in our country. They rely upon their ability to preserve wood on 
 their tendency to "waterproof" it and thus keep it too dry for 
 wood-destroying fungi. The oils are all practically nontoxic 
 although some of them are slightly poisonous to fungi. In order 
 to "waterproof" the wood it is necessary to force comparatively 
 large quantities of the oil into it. This makes crude-oil treated 
 timber quite heavy and very liable to drip oil, especially if ex- 
 posed to a hot atmosphere. 
 
 Three varieties of "crude oil" are in use, viz., crude oil with a 
 paraffin base, crude oil with an asphaltic base, and residuum, 
 which is a product of petroleum distillation. All these crude 
 oils have a gravity less than water, whereas all creosotes are 
 heavier than water. Crude oils with a paraffin base are found in 
 large quantities in Ohio, Pennsylvania, and other states. They 
 are usually lighter in color and gravity than the oils with an as- 
 phaltic base. These latter oils occur in California and part of 
 Texas. Residuum, which is the heavy, rather viscous oil 
 remaining after the distillation of the lighter portions of the 
 crude oil, varies in gravity and viscosity according to the method 
 of manufacture. If too viscous, it cannot be made to penetrate 
 wood. It is best, therefore, when it contains a fairly large 
 percentage of lighter constituents. None of the crude oils 
 penetrate coniferous woods as readily as creosote. This may be 
 due in a large measure to their inability to dissolve the resin in the 
 wood as is done by creosote. The price of crude oils varies from 
 about 2 to 5 cents per gallon. In treating timber^with crude 
 oil it is customary to force as much oil into the wood as it is 
 possible to get in — an amount which varies of course with the 
 different woods. If 12 pounds of oil per cubic foot can be 
 retained in the wood, a heavy impregnation has been secured. 
 
 Creosotes.' — Owing to their ability in preserving wood, 
 creosotes will be discussed in detail, as they are the most im- 
 portant preservatives now known. 
 
 Much misunderstanding exists as to the meaning of the term 
 "creosote." It is defined by the Standard Dictionary as "a 
 colorless to yellowish oily liquid compound consisting of a mixture 
 
 ' The data given on creosotes is largely taken from Circular 206, U. S 
 Forest Service— " Commercial Creosotes "^-by Carlile P. Winslow. 
 
76 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 of phenols distilled from wood, and having a smoky odor and 
 burning taste. It is a powerful antiseptic and is used for the 
 preservation of timber, meat, etc. ; called also oil of wood- tar and 
 oil of smoke." Allen, in his Commercial Organic Analysis, 
 says: "The name 'kreosot' was first applied by Reichenbach, 
 in 1832, to the characteristic antiseptic principle contained in 
 wood-tar. Carbolic acid was discovered soon after by Runge -in 
 coal-tar, and was long confused with the wood-tar principle; 
 and the., crude carbolic acid from coal-tar is still known as 'coal- 
 tar creosote.' Somewhat similar products are now obtained from 
 other sources, so that much confusion has arisen. The term 
 'creosote,' when used without qualification, ought to be under- 
 stood as signifying the product from wood-tar, but it is better 
 to describe Reichenbach's body as 'wood-tar creosote,' and em- 
 ploy the unquaUfied word 'creosote' in a generic sense as meaning 
 the mixed phenols and phenoloid bodies obtained from wood-tar, 
 coal-tar, blast-furnace tar, shale oil, bone oil, or other sources." 
 
 In its original meaning, therefore, the term "creosote" was 
 applied to a product obtained from wood, and the term is still 
 used thus in pharmacy, and refers to a refined product derived 
 from (the destructive distillation of beech or other hardwood. 
 However, with the development of both the wood-preserving 
 and the coal-tar industries, the term "creosote oil," frequently 
 abbreviated to "creosote," gradually came to be applied to the 
 heavy distillates from coal-tar, and the use of the term has be- 
 come more and more extended until, at the present time, it is 
 commonly used in referring to the distillates heavier than water 
 from any tars or tar-like substances, a'nd is even erroneously used 
 to cover products cpntaining admixtures of undistilled tar or 
 pitch. As a result of this lax use of the word it conveys but little 
 to those conversant with the subject and is confusing to those 
 unfamiliar with commercial practice. More specific terms are 
 evidently needed to properly differentiate between the various 
 creosotes. The most useful classification from the wood pre- 
 server's point of view would be one based upon the merits of the 
 various products but lack of sufficient data renders this impossible 
 at this time. The most practical classification at present must 
 be based upon the source and method of production. The 
 following terms and definitions are suggested: 
 
 1. Creosote is a distillate heavier than water obtained by the 
 distillation of a tar or a tar-like substance. 
 
PRESERVATIVES USED IN PROTECTING WOOD 77 
 
 2. Coal-tar creosote is a creosote derived from coal-tar pro- 
 duced by the destructive distillation of coal at a temperature high 
 enough to produce a tar consisting, for the most part, of 
 hydrocarbons of the aromatic series.* 
 
 3. Oil-tar creosote^ (water-gas tar creosote) is a creosote 
 derived from oil tar. This tar may be obtained from the de- 
 structive distillation of petroleum in a gas retort, producing 
 oil-gas as a main product and oil-gas tar as a by-product, or by 
 the cracking of gas oil in the carburetor of a water-gas plant pro- 
 ducing carbureted water-gas as a main product, and carbureted 
 water-gas tar as a by-product. 
 
 4. Wood-tar creosote is a creosote derived from a tar produced 
 by the destructive distillation of wood. 
 
 5. Mixed creosote is a creosote produced by mixing other 
 material with a given creosote, such as another creosote, pitch, 
 undistilled tar, or petroleum, or it may be secured by the dis- 
 tillation of a mixture of two or more tars on tar-like substances. 
 In view of the similarity between certain mixed creosotes and 
 creosotes obtained by the distillation of coal-tar, produced at 
 temperatures sufficiently low to permit the production of hydro- 
 carbons of the paraffin series, these latter distillates are also 
 classed under this heading. 
 
 Source of Tars. — Although there are a variety of tars from 
 which creosotes may be produced, the most important commercial 
 ones may be classified as coal-tars, oil-tars, and wood-tars. The 
 sources and general methods of production of these tars are as 
 follows : 
 
 Coal-tars. — The important coal-tars are derived chiefly from 
 two sources: The destructive distillation of bituminous coal 
 at high temperatures and the combined distillation and com- 
 bustion of bituminous coal at comparatively low temperatures. 
 The first, which furnishes by far the greater proportion of 
 
 ' Creosote secured from coal-tar produced at sufl&ciently low temperature to 
 permit the production of hydrocarbons of the paraffine series might also be 
 included under the name of coal-tar creosote, but in view of the paraffin 
 hydrocarbons it is classed in this publication as mixed coal-tar creosote. 
 
 " Inasmuch as the derivatives of oil-gas tars and water-gas tars contain no 
 phenoloid bodies, the use of the term "creosote" in this connection might, 
 from a purely technical standpoint, be considered erroneous. However, 
 the term is used commercially at the present time in this connection, and a 
 careful consideration of the various definitions used in this publication 
 should prevent any misunderstanding. 
 
78 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 the total supply, is produced in the manufacture of coke and 
 gas in by-product retorts and gas-house plants. Bituminous 
 coal is destructively distilled at temperatures varying from 
 1500° F. to 3000° F., until the charge has been reduced to 
 coke. During the process the ammoniacal liquor and tar are 
 separated from the generated gases by condensation and wash- 
 ing. The tars naturally vary in their properties according 
 to the character of the coal, and of the retorts, and according 
 to the temperatures used. These factors in turn are largely de- 
 pendent upon which of the two main products, gas or coke, is 
 primarily desired; tar acids, however, are always present in the 
 tars and usually the temperatures are sufficiently high in both 
 cases to produce tars consisting largely of hydrocarbons of the 
 aromatic series. 
 
 Coal-tars produced at relatively low temperatures differ from 
 those produced at higher temperatures in the character of their 
 hydrocarboiis. Since the temperatures are not high enough to 
 transform all of the hydrocarbons to the aromatic series, the 
 tars contain, to a greater or less extent, hydrocarbons of the 
 paraffin group. Tars secured from blast furnaces using 
 bituminous coal as fuel and from the Mond producer plants, where 
 bituminous coal is used in the manufacture of gas for power 
 purposes, are representative of this group. The production of 
 such tars, however, is not extensive in this country. 
 
 Oil-tars. — Of the oil tars, that produced in the manufacture 
 of water gas is by far the most important in its relation to the 
 manufacture of creosote. The method of production is, in 
 general, as follows: The "generator" is charged with coke or 
 anthracite coal, which is burned by the aid of an air blast to 
 a cherry red. The hot gases so formed are passed through the 
 "carbureter" and "superheater," which consists of vertical 
 cylindrical chambers filled with a checkerwork of fire brick- 
 After these bricks are heated to the proper temperature the 
 air blast is discontinued and steam is blown into the generator. 
 The gases formed by the contact of the steam with the hot coke 
 or coal pass into the carbureter, into which petroleum "gas oil" 
 is sprayed at the same time. This oil is partially cracked by the 
 high temperature of the fire brick and combines with the gases 
 from the generator to increase their illuminating power; the 
 process of cracking continues through the superheaters. The gas 
 is then passed to the condensers and washers, where tar is con- 
 
PRESERVATIVES USED IN PROTECTING WOOD 79 
 
 densed and collected. This tar differs in its constituents from 
 coal-tar produced in the by-product coke ovens and gas retorts 
 both in the absence of tar acids and in the presence of hydrocar- 
 bons of the paraffin series; usually, however, the quantity of 
 paraffin hydrocarbons present is comparatively small. 
 
 Some oil-tar also is produced by the destructive distillation 
 of crude petroleum in the manufacture of oil gas. In tars from 
 this source the quantity of paraffin hydrocarbons present is 
 generally much greater than in that produced in the manufacture 
 of carbureted water gas. 
 
 Wood-tars. — Wood-tar is produced in a manner somewhat 
 similar to that in which by-product coal-tar is formed. Wood is 
 destructively distilled in retorts, and charcoal is produced, together 
 with gas and a liquid distillate which consists largely of pyro- 
 ligneous acid and a product called crude tar. The tar and acid 
 are separated by settling and by distillation. Wood-tars are quite 
 different from coal-tars and contain, in particular, less of the 
 aromatic hydrocaibons. 
 
 Distillation of Creosote from Tars. — From any or all of the 
 foregoing tars, either alone or in mixture, creosote may be pro- 
 duced. The general process of manufacture is similar in all 
 cases. The tar is distilled in a metal retort or still and the vapors 
 are condensed and collected. Those distillates which are heavier 
 than water form the true creosotes used in wood preservation. 
 The temperatures at which the creosotes are obtained vary greatly, 
 but generally lie between about 200° and 360° C. The actual 
 temperatures in each case depend largely upon the character 
 of the residue desired. In the United States the manufacture 
 of creosote from coal-tar is generally secondary to the manu- 
 facture of soft pitch; and in such cases the maximum tempera- 
 ture during the distillation is comparatively low. In Europe, 
 on the other hand, coal-tar is distilled largely for the production 
 of the coal-tar dyes, and the distillation is carried to higher tem- 
 peratures. The creosote, therefore, contains a relatively greater 
 amount of the higher boiling constituents than the American 
 product. 
 
 As already stated, pitch, undistilled tar, or other similar mate- 
 rials are frequently mixed with a creosote, and while such mixtures 
 are sometimes sold as creosotes, the term is improperly applied 
 except as it relates to the distilled product. 
 
 The complexity of the many hydrocarbons and their de- 
 
80 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 rivatives which may be produced in the destructive distillation 
 of coal, oil, and wood makes it impossible to state precisely the 
 nature of the various constituents of all creosotes. However, 
 they may be broadly divided into two classes, compounds of the 
 aromatic series and compounds of the paraffin series. The 
 characteristic difference between the two lies in the greater chemi- 
 cal activity of the former. Coal-tar creosote consists almost 
 wholly of aromatic compounds, and the long period of successful 
 use of such creosote has led to the general feeling that these con- 
 stituents are the more desirable. 
 
 The compounds of the aromatic series may be divided into 
 three groups, as follows: (1) "Light oils," which distill below 
 205° C. and consist largely of phenols and cresols, or tar acids; 
 (2) naphthalenes, which distill between approximately 205° 
 
 BituminouB Coal 
 
 Oils Lighter thaa Water Oils Heavier 
 
 than Water 
 
 Cre;OBOte 
 
 "reot 
 DiBtillation Limita and Greneral Nature of the Aromatic ConatituentB 
 
 Light Oils 
 Bichin Phenols 
 
 Naphthalenes 
 
 Constituents of an Anthracene Nature 
 
 Liquid at Hoom Solid at Boom Liquid at Boom I Solid at Boom 
 
 Temp. Temp. Temp, I Temp. 
 
 205 C. 255 C. 295 C. SOOlj, 
 
 Fig. 6. — Derivation of coal-tar creosote. 
 
 and 255° C; and (3) constituents of an anthracene nature dis- 
 tilling above 255° C, which will be referred to collectively 
 as "anthracenes." Some or all of these are found in most 
 creosotes. 
 
 Of these constituents the tar acids possess the highest anti- 
 septic properties; they are, however, soluble in water and are 
 more volatile than the other constituents. The naphthalenes and 
 anthracenes are neither so antiseptic nor so volatile as the tar 
 acids and are practically insoluble in water. There is much 
 discussion as to the relative value of these different constituents, 
 but, largely as a result of experience, the presence of tar acids is 
 believed by many to be essential. While a large proportion of 
 naphthalene is sometimes advocated, particularly for the pres- 
 ervation of piling, a reduction in the quantity of this constituent, 
 
PRESERVATIVES USED IN PROTECTING WOOD 81 
 
 with a corresponding increase in the amount of anthracenes, is 
 believed to increase the value of a creosote for general purposes. 
 
 Coal-tar Creosote. — Fig. 6^ shows graphically the derivation 
 and general composition of coal-tar creosote. The relative 
 quantity of tar acids, naphthalenes, and anthracenes will of 
 course vary according to the character of the tar and the tem- 
 peratures used during its distillation, but generally the tar acids 
 present will not exceed 5 percent, the naphthalenes will comprise 
 from 15 to 50 percent, and the anthracenes will comprise the 
 remainder. As previously defined, it contains practically no 
 paraffin hydrocarbons. The creosote as a whole is antiseptic, 
 insoluble in water, and somewhat volatile; it is sufficiently free 
 from "free carbon," and fluid enough at temperatures used in com- 
 mercial treating plants, to offer no great resistance to entrance 
 into the wood. 
 
 Tests made at the U. S. Forest Products Laboratory show the 
 toxic limit of coal-tar creosote to be between 0.2 and 0.4 per 
 cent. Very small amounts of it will therefore protect wood from 
 decay. In general, the lighter fractions are more toxic than the 
 heavier fractions. They are also far more volatile and when 
 injected into wood by themselves evaporate at a rapid rate (Fig. 
 30). The heavier constituents of coal-tar creosote are there- 
 fore, in addition to being slightly toxic, of direct value in helping 
 to retain in the wood these lighter oils. The permanency of 
 the heavier oils is well illustrated by an analysis made of a pile^ 
 in actual service in the Gulf of Mexico for 30 years. This pile 
 was cut into three sections, samples from which were then ex- 
 tracted for creosote, with the results shown in Fig. 7. 
 
 Numerous similar examples could be cited, all of which show 
 that the lighter fractions of coal-tar creosote are not permanent. 
 While considerable heated discussion has occurred as to their 
 value,' it is the author's opinion that these lighter oils have 
 distinct merit in prolonging the life of timber, and if they had 
 been absent entirely from the creosote, it is doubtful if such long 
 periods of service could have been secured. 
 
 ' In Figs. 6 and 8 the term "solid at room temperature" (20° C.) is 
 used in describing the condition of certain of the fractions distilled from 
 creosote, when, at the ordinary temperature of a room, they retained their 
 position in the receiving flask when vigorously shaken. 
 
 ' U. S. Forest Service Circular 199, "Quantity and QuaUty of Creosote 
 Found in Two Treated Piles after Long Service," by E. Bateman. 
 
 ' "The Preservation of Timber," by S. B. Boulton, 1885. 
 
 6 
 
82 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 Coal-tar creosote does not corrode iron to any appreciable 
 degree (see Table 5) and for this reason is admirably adapted 
 for use in the steel cylinders of modern timber treating plants. 
 
 When heated, the vapors arising from the oil may attack the 
 skin and cause a very irritating swelling and burning. This 
 effect is not produced on most people, but complaints have been 
 
 8U 
 
 
 
 1 
 
 
 
 
 
 
 
 
 
 
 
 j-j 
 
 70 
 
 
 
 
 
 
 
 
 
 
 
 
 
 / 
 
 f 
 
 
 
 
 
 
 
 
 
 
 
 
 > 
 
 
 
 
 60 
 
 
 
 
 
 
 
 
 
 
 
 / 
 
 A 
 
 V 
 
 
 
 
 
 
 
 
 
 
 
 ,/ 
 
 /• 
 
 A 
 
 » 
 
 
 50 
 
 
 
 
 
 
 
 
 
 y 
 
 Z' 
 
 / 
 
 / 
 
 
 
 
 
 
 
 
 
 •-' 
 
 X 
 
 
 / 
 
 / 
 
 
 
 
 s, 
 s 
 
 g 40 
 
 
 
 
 
 -•-■ 
 
 ->- 
 
 
 (Y 
 
 ^ 
 
 / 
 
 
 
 
 
 
 
 ^ 
 
 /• 
 
 
 n-' 
 
 ^ 
 
 .^ 
 
 / 
 
 r 
 
 
 
 
 
 30 
 
 
 
 I 
 
 r/ 
 
 ^ 
 
 
 
 / 
 
 r 
 
 
 
 
 
 
 
 
 
 / 
 
 
 
 / 
 
 / 
 
 
 
 
 
 
 
 20 
 
 
 
 
 
 
 
 / 
 
 
 
 
 
 
 
 
 
 
 
 / 
 
 
 
 
 
 
 
 
 
 10 
 
 
 / 
 
 1 
 
 
 / 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 / 
 
 r 
 
 
 
 
 
 
 
 
 
 
 
 
 •- 
 
 
 W^ 
 
 / 
 
 
 
 
 
 
 
 
 
 
 
 200 210 220 230 240 250 260 270 280 290 300 310 320 330 340 
 Temperature "Centigrade 
 Ijegend 
 
 • Creosote taken from Section in the Mud 
 O Creosote taken from Section in the "Water 
 O Creosote taken from Section above the Water 
 
 P'iG. 7. — Distillation of creosote remaining in a pile after 30 years' service. 
 
 made by workers who come in contact with creosoted timber, 
 particularly trackmen, and several law suits have resulted. Even 
 the cold oil may produce such an injury. It is not, however, 
 serious and, with caution in handling the treated timber, even a 
 sensitive person can become immune to any discomfort. 
 
 The price of coal-tar creosote varies considerably and for the 
 past few years has been steadily rising. In large quantities the 
 
PRESERVATIVES USED IN PROTECTING WOOD 83 
 
 average price in eastern United States is now about 6 to 9 cents 
 per gallon. In the West, the price is from two to three times 
 this amount, and, in small orders, even more. The sharp 
 demand for the oil, and its present limited production give little 
 hope that the price will lower materially in the immediate future. 
 Much discussion has occurred concerning the quality of 
 creosote best suited to the treatment of timber. Until recently 
 discussion has resulted in little practical value because the 
 demand for the oil was so great the consumer was glad to receive 
 most any kind he could get. Now, however, several grades of 
 coal-tar creosote can be obtained, but no uniformity exists as 
 yet as to the quality best suited to preserve wood. Most authori- 
 ties agree that a comparatively heavy grade is better than a light 
 grade. The specifications which are perhaps in most extended 
 use at present in the United States are the ones adopted by the 
 American Railway Engineering Association. They allow three 
 grades of oil, the specifications reading as follows : 
 
 "Grade 1 Oil. — ^The oil used shall be the best obtainable grade of coal- 
 tar creosote; that is, it siiall be a pure product obtained from coal gas 
 tar or coke oven tar and shall be free from any tar, oil or residue ob- 
 tained from petroleum or any other source, including coal gas tar or 
 coke oven tar; it shall be completely liquid at 38° C. and shall be 
 free from suspended matter; the specific gravity of the oil at 38° C. 
 shall be at least 1 . 03 when distilled by the conunon method — that is, 
 using an 8 ounce retort, asbestos covered, with standard thermometer, 
 bulb 1 /2 inch above the surface of the oil — the creosote, calculated on the 
 basis of the dry oil, shall give no distillate below 200° C, not more than 
 5 percent below 210° C., not more than 25 percent below 235° C. and the 
 residue above 355° C. if it exceeds 5 percent in quantity, shall be soft. 
 The oil shall not contain more than 3 percent water." 
 
 Grade 2 oil, which is considered "next best," is similar to the 
 "standard" just quoted except for the amount of fractions dis- 
 tilled at varying temperatures, these being " not more than 8 per- 
 cent below 210° C. and not more than 35 percent below 235° C." 
 
 Grade 3, which is poorer than Grade 2, differs from it only 
 in specific gravity and the amount of distillates at various tem- 
 peratures, these differences being "the specific gravity at 38° C. 
 shall be at least 1.025. Not more than 10 percent of the 
 oil shall distill below 210° C; not more than 40 percent below 
 235° C." 
 
 The specification in use by the U. S. Forest Service is slightly 
 
84 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 more rigid than the above, particularly as regards the method 
 of analyzing the oil (see appendix). Most of the confusion which 
 has occurred concerning the proper kind of creosote to use has 
 come through lack of definite data. Commercial motives and 
 an attempt on the part of certain "experts" to mystify the trade 
 have also added to the complexity of the situation. In all 
 probability, as experience grows the situation will clear and 
 specifications for coal-tar creosote will be drawn depending on the 
 use to which the oil is to be put. Until such data is available 
 the safest course to pursue is to demand a comparatively heavy 
 oil of known purity. 
 
 In treating paving blocks a heavy oil is generally used, the 
 idea being that it will stay in the wood and will have a marked 
 waterproofing effect. Thus the "Association for Standardizing 
 Paving Specifications" adopted in 1911 the following grade of oil: 
 
 Coke or Anthracite 
 Steam and 
 Petroleum 
 
 Tar 
 
 I 
 
 Oils Ligliter Oils Heavier tiian JPitch or Coke 
 
 than Water Water Creosote 
 
 General Distillation Limits of the Gonstitnents 
 
 Possibly 
 Naphthalene 
 
 Solid at Boom 
 Temp. 
 aoVo. 2 
 
 Possibly of an Anthracene Kature but Grcnerally 
 containing Paraffin Hydro Carbons 
 
 Liquid at Boom 
 Temp. 
 
 Liquid at Boom 
 Temp. 
 
 Solid at Boom 
 Temp. 
 
 Fig. 8. — Derivation of water-gas-tar creosote. 
 
 "The preservative to be used shall be a coal-tar product, free from 
 adulteration of any kind whatever, and shall comply with the 
 following requirements. (1) The specific gravity shall be not less 
 that 1.10 or more than 1.14, ata temperatute of 38° C. (2) Not 
 more than 3§ percent of the oil shall be insoluble by hot continu- 
 ous extraction with benzol and chloroform. (3) On distillation, 
 which shall be made exactly as described in Bulletin 95 of the 
 American Railway Engineering and Maintenance of Way Associa- 
 tion, the distillate shall not exceed 2 percent up to 150° C. and 
 shall be not less than 30 or more than 40 percent up to 315° C." 
 It is thus apparent that the oil need not be a coal-tar " creosote" 
 and must contain a considerable amount of the heavier con- 
 
PRESERVATIVES USED IN PROTECTING WOOD 85 
 
 stituents in coal-tar m order to have the gravity required. This 
 matter is also discussed in Chapter XIII. 
 
 Water-gas-tar Creosote. — Of the oil-tar creosotes, that from 
 water-gas tar is practically the only one used for wood preserva- 
 tion. Fig. 8 illustrates its derivation and general composition. 
 This creosote is not more volatile nor soluble in water than coal- 
 tar creosote, contains no "free carbon," and offers no marked re- 
 sistance to entrance into the wood. In fact, water-gas-tar 
 creosote may be produced which on fractional distillation will 
 display a great similarity to coal-tar creosote. There is a dif- 
 ference, however, in the constituents of the two creosotes, as 
 shown by the difference in certain physical properties of fractions 
 distilled from them at equal temperatures. Furthermore, water- 
 gas-tar creosote is distinctive in the absence of phenols and cre- 
 sols, and usually in the presence of hydrocarbons of the paraffin 
 group; it is not so antiseptic as coal-tar creosote. Unfortunately, 
 quantities of this oil are mixed with coal-tar creosote, so that it is 
 often impossible in practice to detect its presence. While this 
 oil undoubtedly has considerable merit as a preservative of timber, 
 there is not sufficient precise data available to warrant giving it the 
 confidence which the coal-tar product now enjoys. Careful tests 
 show its toxicity to be about 3 to 4 percent as compared with coal- 
 tar creosote, which has a toxic limit of from 0.2 to 0.4 percent. 
 The most reliable tests known to the author were made by the 
 U. S. Forest Service in treating mine timbers (see Chapter XII) 
 which failed to last as long as similar timbers treated with the 
 coal-tar creosote. 
 
 Although it is slightly more corrosive of iron than creosote from 
 coal-tar, its action is so slight that its use in steel cylinders can- 
 not be considered objectionable on this account. 
 
 The price of water-gas-tar creosote is seldom quoted but it is 
 generally a cent or two a gallon less than the coal-tar product. 
 There is no doubt but that much of this oil is sold as a coal-tar 
 creosote either alone or in combination and as such commands 
 the same price. 
 
 The National Electric Light Association is the only association 
 known to the author which has framed a specification for water- 
 gas-tar creosote to be used in preserving wood. This specifica- 
 tion reads as follows : 
 
 "Itshallhavea specific gravity of at least 1.03 and not morethanl-08 
 at 38° C. There shall be not over 1 percent of residue insoluble in hot 
 
86 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 benzol. The oil shall contain not over 2 percent of water. The residue 
 remaining upon sulphonating a portion of the total distillate shall not 
 exceed 5 percent. When 200 grams of the oil are distilled in accordance 
 with the requirements of the specifications for the analysis of water gas 
 tar, dead oil or water-gas-tar creosote and the results calciilated to water 
 free oil (a) not more than 2 percent of oil shall^ distill off up to 205° C, 
 (6)' not more than 10 percent shall distill off up to 235° C, (e) not more 
 than 60 percent shall distill off up to 315° C, (d) the coke residue shall not 
 exceed 2 percent." 
 
 The method of analysis referred to calls for a 300 c.c. side-neck 
 Lunge distilling flask provided with a trap.^ 
 
 Wood-tar Creosote. — Of the wood-tar creosotes, that most used 
 in the past has been secured from resinous woods. The derivation 
 
 Besinoua Woods 
 
 I 
 
 Gas Liquid 
 
 Charcoal 
 
 Pyroligneoua Acid 
 
 I 
 
 Oils Lighter than Water 
 Turpentine 
 
 OilB Heavier than Water. 
 Creoaote 
 
 Fig. 9.^Derivation of wood-tar creosote. 
 
 of such creosotes is illustrated in Fig. 9. Lack of authentic data 
 prevents even a general statement as to its constituents, but the 
 proportion of tar acids and volatile constituents is generally great- 
 er, and of naphthalene and anthracene much less, than in the coal- 
 tar creosotes. Wood-tar creosotes have been used to some extent 
 as wood preservatives for many years. They are, as a rule, not as 
 toxic as coal-tar creosote, their resistance being from about 10 to 
 50 less than the coal-tar product. 
 
 On account of the comparatively large amount of acids which 
 they contain, they corrode iron to a much greater extent than the 
 coal-tar oil and their use in this connection may be considered 
 objectionable. It is but fair to state, however, that this property 
 could be largely overcome if the acids were removed from the 
 oil. Their supply has been so limited and cost so comparatively 
 
 ' Report of Committee on Preservative Treatment of Poles and Cross- 
 Arms," National Electric Light Association, June, 1911. 
 
PRESERVATIVES USED IN PROTECTING WOOD 87 
 
 high that little serious attention has been paid to them except 
 in the manufacture of certain patented products and "stains." 
 The rapid rise in the price of coal-tar creosote and its limited 
 supply have of late attracted considerable attention to the 
 creosotes from wood, hence it is likely their use in preserving 
 wood may become more general in the future. 
 
 At present these oils are rarely quoted below 12 cents per 
 gallon even in large quantities, so that the coal-tar product must 
 rise appreciably or the price of the wood-tar oils must fall 
 appreciably before their extensive use will occur. In addi- 
 tion to the tars from resinous woods, there is no good reason 
 why the tars from hard woods cannot be used in manufacturing 
 creosotes. If this is done a larger output will be possible. Just 
 now, no stability in composition is recognized in wood creosotes 
 for preserving timber and hence no general specification for them 
 exists. 
 
 Mixed Coal-tar Creosotes — A large part of the creosote pro- 
 duced in this country falls into the class of mixed coal-tar 
 creosote. Some is made by the mixture of undistilled coal-tar, 
 or oil-tar, or pitch, with coal-tar creosote ; some is produced by 
 the partial distillation and combustion of bituminous coal at 
 comparatively low temperatures; and some is secured through 
 the manufacture of soft pitch when coal-tar and water-gas tar 
 are distilled in admixture. The nature of all mixed coal-tar 
 creosotes cannot be described, because their constituents and 
 relative merits as wood preservatives vary in each case accord- 
 ing to the materials used in their production and preparation. 
 Admixtures of undistilled tar or pitch containing free carbon 
 will, however, tend to decrease the penetrance of the creosote, 
 while the admixture of products which contain appreciable 
 amounts of constituents of the paraffin series will doubtless 
 affect in some measure the antiseptic properties of the creosote. 
 
 Paints and Stains. — Wood which has been painted with 
 ordinary paint (usually a mixture of linseed oil, turpentine, and 
 an inorganic pigment.) such as is used in decorating buildings is 
 partially protected from decay because it is rendered partially 
 waterproof. The spores of wood-destroying fungi will not 
 develop readily on the surface of painted wood. To secure best 
 results only air-seasoned wood should be painted, as green wood 
 will be very liable to surface check and expose the untreated 
 interior. Furthermore paint will not adhere as well to green 
 
88 [THE PRESERVATION OF STRUCTURAL TIMBER 
 
 timber. The layer of paint usually adheres to the surface of 
 the wood and has little or no penetrating power. Moreover, 
 it is generally porous so that certain amounts of water can pass 
 through it. Judged as a preservative of timber, ordinary 
 paint must be considered inefficient and under certain conditions 
 may even do the timber more harm than good, as it tends to 
 equalize moisture in the wood and thus render the interior more 
 favorable to decay. 
 
 Stains, on the other hand, penetrate the wood, although as a 
 rule only a slight distance from the surface. In addition, they 
 are generally toxic, so that fungi coming in contact with them 
 will be killed. The composition of stains varies greatly but they 
 commonly have a base of creosote either from coal-, oil-, or wood- 
 tars, to which is added a vegetable or mineral oil to act as a 
 body for the pigment they carry. Best results with stains are 
 secured by applying them only to thoroughly air-dry wood, and 
 whenever possible heating them slightly so that greater pene- 
 trating power is obtained. As a rule, stains are better pre- 
 servatives of wood than paints, and their use, particularly 
 for dwellings, has become very popular of late. 
 
CHAPTER VII 
 
 THE CONSTRUCTION AND OPERATION OF WOOD 
 PRESERVING PLANTS 
 
 In Chapter V we described the relative merits of the open- 
 tank and pressure plants and the general features of their opera- 
 tion dependent upon the particular process selected. In this 
 chapter we will describe the construction of the plants, the 
 effect of the various mechanical manipulations used in them, 
 such as pressure, vacuum, etc., and the cost of building the 
 plants. 
 
 Open-tank Plants. — Several types of open-tank plants have 
 been constructed. Perhaps the simplest consists in fitting an 
 iron pipe 3 or 4 inches in diameter, blind at one end, into a 
 wooden or iron barrel. A fire is then built around the pipe, 
 which thus heats the oil in the barrel. With wooden barrels 
 trouble is likely to be experienced in maintaining tight joints. 
 If desired 2 barrels can be joined together with one piece 
 of pipe about 8 feet long, and the capacity of the plant thus 
 doubled. Plants of this kind cost less than $5 each. (See Plate 
 VII, Fig. A.) 
 
 Another simple method consists in building a fire directly 
 under an iron barrel or tank which is mounted upon stones to 
 form a proper foundation and fire box. More effective results 
 are secured by walling the vessel with brick or stone, thus 
 allowing the heat to pass around the sides as well as the bottom. 
 The draft can also be controlled through a small pipe. (See Plate 
 VII, Fig. B.) Plants of this type cost from $10 to $25 each. 
 
 In the types just described, it is diflBcult to control the in- 
 tensity of the heat. Better results can be secured if steam is 
 employed, this being passed through coils in the bottom of the 
 tank. Plate VII, Fig. C, shows such an apparatus in which the 
 steam is supplied by a traction engine. In order to cheapen 
 the cost of the tank, sheet or galvanized iron reinforced in a 
 wooden frame may be used in place of heavier metal. If desired 
 a second tank capable of submerging the entire timber in cool 
 
 89 
 
90 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 preservative can be used and the capacity of the plant thereby 
 increased. Such a plant including piping costs about $50. 
 
 A still more elaborate type consists in building a large rec- 
 tangular or cylindrical open tank of 1/4-inch or 5/16-inch iron 
 of various dimensions depending upon the size of the material to 
 be treated, and pumping the preservative into it after the wood has 
 been placed in position. This necessitates, in addition to the 
 treating tank, a good force pump, boiler, and auxiliary tanks to 
 hold the preservative. Plants of this kind are well adapted for 
 treating larger quantities of timber than would ordinarily be the 
 case in the plants described above, or heavier timbers such as 
 poles. Their cost varies, of course, with their size, but will range 
 from about $2000 to 16000. One similar to that shown in Plate 
 VI, Fig. C, cost $2500 complete. 
 
 All the plants above described are aimed to heat only a portion 
 of the timber, although the entire stock can in some cases be 
 submerged in the preservative should this be considered neces- 
 sary. Another type of plant for treating comparatively large 
 quantities of small timber such as ties and poles consists in 
 passing them through the hot preservative by means of an 
 endless chain, the length of time they are in the preservative being 
 controlled by the speed of the chain. Such a plant is shown in 
 Plate VII, Fig. D, and has been used with satisfactory results by 
 a traction company in New Jersey. It cost about $1600 and 
 has a capacity of about 1200 ties per 10-hour day. Because 
 of the large surface exposed, only those preservatives which 
 volatilize at high temperatures should be used if most economic 
 results are to be secured. Treatments in plants of this kind are 
 really nothing but prolonged dipping reatments and in this respect 
 differ from the Giussani process, which submerges the wood in a 
 subsequent bath of cool preservative by passing it through a 
 second tank. 
 
 Pressure Plants. — Considerable quantities of timber are most 
 efficiently handled in pressure plants, which fact accounts for the 
 14rge number now operating in this and foreign countries. (See 
 Plate VI, Fig. D and Plate VIII, Fig. A.) The essential features 
 in all plants operating on this basis are quite similar, although 
 the details of construction and operation vary through wide 
 limits, these depending upon the opinions and experience 
 of their builders and the class of work the plant is to handle. 
 In general, the following units are characteristic of all pres- 
 
Plate VII 
 
 Fig. a. — ^A post treating plant made of two barrels and an iron pipe. (For- 
 est Service photo.) 
 
 ■piQ p An open tank post treating plant — California. (Forest Service 
 
 photo.) 
 
 (FaciTig poge 90.) 
 
Plate VII 
 
 Fig. C. — An open tank post treating plant. Note heat is furnished by 
 steam from threshing engine. Small cylindrical tank is for butt treating in 
 a hot bath; rectangular tank is for a cold bath. (Forest Service photo.) 
 
 Fig. D. — Open tank wood preserving plant for ties. The ties are carried 
 through the plant on an endless chain. (Photo through courtesy of the' 
 Public Service Corp., Newark, N. J.) 
 
OPERATION OF WOOD PRESERVING PLANTS 91 
 
 sure plants: (1) A retort house, (2) a pump house or 
 room, (3) a boiler house, (4) a machine shop or room and (5) a 
 yard for storing, loading, and handling the timber. Some plants 
 are also equipped with a sawmill for framing the timber prior to 
 its injection with preservatives. The arrangement of these 
 units in a typical plant is shown in Fig. 10. Variations, of 
 course, occur, especially if the plant is to operate a special process, 
 or only on a given kind of timber. Furthermore, the cylinders 
 may vary in number from 1 to 9 or more, in which case a different' 
 arrangement of the units would be made. 
 
 Plan Showing Yard Layout 
 
 Fig. 10. — Plan showing layout of a typical wood preserving plant. (Draw- 
 ing through courtesy of the Ry. Eng. and M. of Way.) 
 
 The Retort House. — The retort house is built primarily to cover 
 and protect the treating cylinders or retorts. In best con- 
 struction it is made of steel, brick, or re-enforced concrete, al- 
 though a wooden structure may be used if minimum cost is 
 desired. To guard against loss of preservative due to leaks, 
 or accident, the floor is sometimes made of solid concrete with 
 appropriate drains to a sewer or underground tank, and de- 
 pressed so that the level of the rails in the retorts will be the same 
 as that of the outside tracks. It is well to so construct the build- 
 ing that a free ventilation can be obtained to carry off the vapors 
 which frequently arise during the operation and to keep the 
 temperature in the house from becoming oppressive to the 
 workmen. 
 
 Retorts (or Cylinders). — These are invariably built of steel 
 and are cylindrical shells mounted horizontally upon concrete 
 piers. Their diameter varies from about 6 to 9 feet, and length 
 from about 50 to 180 feet. A good size is 7 feet X 132 feet. 
 The 7-foot diameter enables a more economic utilization of space 
 in the cylinder than a smaller diameter and is not too large to 
 
92 THE PRESERVATION OP STRUCTURAL TIMBER 
 
 make the handling of the cylinder cars expensive and clumsy. 
 The same reasoning applies to a length of 132 feet or thereabouts. 
 The thickness of the metal in the retorts varies from about 5/16 
 to 1 inch. Good practice is to use metal of such thickness that 
 working pressures of 150 to 175 pounds can be safely used. In 
 some cases lower pressures of 100 to 125 pounds give satisfaction. 
 The plates of which the retorts are made are riveted with either 
 butt or lap joints. For high pressures the former is the more satis- 
 factory. In order to completely drain the retorts a slight pitch is 
 given them. It is very important to have the retorts mounted 
 upon firm piers, or trouble from buckling is likely to occur. If 
 the plant is built on marshy ground the piers should be made 
 wide at the base and close together or mounted on piles. The 
 retort is perforated to admit pipes, gauges and thermometers, and 
 often has a small dome riveted on the top and in the middle to 
 act as an expansion chamber for the contained air and oil. 
 
 Retort Thermometer. — The manner of placing the retort 
 thermometer is very important or incorrect readings of tem- 
 perature will result. The bulb of the thermometer should not 
 be too close to the shell of the retort but should be at least 2 
 inches from it. The thermometer preferably should be inserted 
 near the middle of the retort and half way up. In order to be 
 sure of the reading a pet cock should be inserted in the ther- 
 mometer plate and some oil drawn off during the treatment. 
 In addition to the direct-reading thermometer, recording ther- 
 mometers are also highly desirable, as they give a complete record 
 of temperature during the entire treatment and enable the 
 manager to get an accurate check on his men. Care should be 
 exercised to see that the thermometer is properly calibrated and 
 guarded against the men tampering with it. By ascertaining the 
 temperature at various points in the retort (by means of a 
 maximum and minimum thermometer) the thermometer inserted 
 in the shell can be calibrated to give the average reading in the 
 cylinder. 
 
 Retort Gauges. — These are inserted in the retort to record the 
 pressures in it, whether above or below atmospheric. They may 
 be inserted at any convenient point in the top of the shell. If 
 direct reading, the gauges should be protected from injury by 
 preservative by means of a water seal or diaphragm. The 
 author's experience with combination pressure and vacuum 
 gauges has not been satisfactory and it is beheved separa,te gauges 
 
Plate VIII 
 
 Fig. a. — Small wood preserving plant designed by the U. S. Forest 
 Service in co-operation with the Louisiana Creosoting Co. (Forest Service 
 photo.) 
 
 Fig. B. — View through a large treating cylinder. Note guard rails, steam 
 coils and track. International Creosoting and Construction Company. 
 
 (^Facing page 92.) 
 
Plate VIII 
 
 Fig. C. — Spider door with independent sockets. (Photo, through courtesy 
 of the Allis Chalmers Mfg. Co.) 
 
 Fig. D. — Spider door with continuous socket support. (Photo through 
 courtesy of the Allis Chalmers Mfg. Co.) 
 
 Fig. E. — Construction of a cast steel door. (Photo through courtesy of 
 the Allis Chalmers Mfg. Co.) 
 
OPERATION OF WOOD PRESERVING PLANTS 93 
 
 give better results. Self-recording gauges are highly recom- 
 mended. 
 
 Anchors and "Turtles." — As the temperature of the retort 
 varies considerably, it is necessary to anchor the retort and also 
 allow for its expansion and contraction. Anchorage can best be 
 made at the middle. There are several methods of doing this 
 but embedding a channel or angle iron riveted to the retort 
 in a concrete pier or "tie rods" in two piers prove satisfactory. 
 In some plants the retorts rest in cast-iron saddles or "turtles," 
 which are permitted to slide back and forth over plates embedded 
 in the piers, thus providing for expansion. In other cases the 
 turtles are made of wood. Although steel rollers are sometimes 
 used to permit a freer movement of the "turtles," they are not 
 necessary, as equally satisfactory results can be obtained by 
 simply permitting the expansion and contraction to take place over 
 flat surfaces. 
 
 Retort Coils. — Steam coils placed in the bottom of the retort, 
 generally over its entire length in order to heat the preservative, 
 are a source of constant expense and trouble unless they are 
 properly laid, as they dilute the preservative with steam and cause 
 leakage of the preservative. (See Plate VIII, Fig. B.) The im- 
 portance of first-class construction in these coils cannot be over- 
 emphasized. A few plants omit the coils but as a general rule 
 they are necessary for best results. Common practice consists 
 in screwing extra heavy 1 1/4 to 2-inch pipes into extra heavy 
 return bends or headers. If this is done only sharp threads should 
 be used and no white lead or any similar material should be 
 permitted in order to makethe joints tight. Two schemes which 
 appear meritorious are to use cast-iron radiators in place of coils, 
 these being coupled in series, or to place one steam pipe in- 
 side another, leaving one end free so that it can expand and 
 contract at will. This latter device has been found very satis- 
 factory in practice. In order to protect the coils from possible 
 injury due to derailment and from dirt off the timber, per- 
 forated steel plates are frequently laid over them. 
 
 Guard Rails. — When the cylinder cars loaded with wood are run 
 into the treating retorts, the tendency is for them to float off the 
 track after the perservative is admitted. This is because the 
 buoyant force exerted by the wood is greater than the dead weight 
 of the cars. To overcome the possibility of such trouble, guard 
 rails are generally used. Three types of such guard rails are in 
 
94 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 use. In one an angle iron is bolted to the seats riveted to the 
 shell of the cylinder. The car with its load can float partially off 
 the tract equal to the distance between the top of the retort and 
 the top of the iron bale or hoop fastened to the car — a space usually 
 of 1 1/2 to 3 inches. As the preservative is run from the cylinder 
 the car gradually settles into position on the track. 
 
 In the other two types a projecting flange is generally riveted 
 to the cylinder car, which slides under the guard rail and thus 
 prevents the car from floating, the only difference in the two 
 types being that in one the projecting flange is riveted on the 
 bottom of the car, while in the other it is on top of the frame. 
 
 Retort Doors. — These may be fastened on one or both ends of the 
 treating cylinder, depending largely upon the ease with which 
 the timber can be handled in the yard. Retorts with but one 
 door are entirely satisfactory and in the author's opinion are 
 preferable to retorts with doors at both ends. When one door is 
 used the other end of the cylinder is closed with a dished head, 
 thus saving extra expense and often trouble. Retort doors are 
 always fitted to cast-iron or steel rims or "collars" riveted to the 
 shell of the cylinder. These collars are machined with a dove- 
 tailed groove to hold a gasket against which the "tongue" on the 
 door can press. Asbestos rope pounded into this groove and its 
 surface kept well lubricated with graphite and oil makes a very 
 satisfactory packing. 
 
 There are several types of doors but they may be classed 
 into two groups, "spider doors" and "bolt doors." The former 
 enable the cylinder to be opened and locked easily and quickly, 
 and for this reason are preferred by some. They are, however, 
 more expensive than bolt doors and are more liable to get out of 
 adjustment and cause leaks. Two kinds of spider doors are 
 generally used. The one shown in Plate VIII, Fig. C, has a 
 center screw and lever nut arranged so that each lever has an 
 independent connection to the frame. The type shown in Plate 
 VIII, Fig. D, is stronger and better constructed and so arranged 
 that the levers are connected to the frame by a continuous- 
 flange ring. Both of these types swing on hinges. 
 
 Most treating plants now use some form of bolt door, as the 
 small tim« of opening and closing is not a very important factor, 
 their cost is low, and their construction simple and efficient. 
 There are several types of bolt doors and several methods of 
 arranging the bolts. A good type is one constructed of solid 
 
OPERATION OF WOOD PRESERVING PLANTS 95 
 
 cast steel, with independent Tee-bolts fastened to the cylinder 
 and swinging on hinges without a wheel support. This is 
 shown in Plate VIII, Fig. E. Doors are sometimes constructed 
 of a cast-steel rim to which is riveted to a dished-steel plate. 
 Such -doors are light in weight but not as strong as those of 
 solid cast steel. (See Plate IX, Figs. A and B .) In some plants the 
 ,bolts are not mounted to the cylinder but simply rest in slots 
 so they can be rernoved when not in use. This is the cheapest 
 construction but not as good as where the bolts are fastened and 
 hence always in position ready for use. Bolts with an "eye" 
 in place of a "Tee" are also used, being fastened to a ring which 
 passes through the eye, which is in turn tapped to the collar on 
 the cylinder. This construction is very satisfactory but has an 
 objection in that if one bolt becomes damaged it is necessary to 
 remove all those fastened to the portion of the ring on which it 
 swings in order to make repairs. However, as such damage 
 occurs but seldom and as this construction is cheaper than the 
 independent Tee-bolts, it has very much merit in its favor. 
 
 It is very important to properly imbed the curved iron plate 
 or rail upon which the door wheel rolls or the door will either 
 jam or not rest on the wheel. Furthermore, improper founda- 
 tions will throw the cylinder out of alignment and render the 
 wheel useless. 
 
 In order to avoid hinges, doors are sometimes cast without them, 
 as is shown in Plate XI, Fig. C. In this case they are supported 
 on a small derrick or overhead track so they can be swung or 
 run out of the way during the transfer of the cars. Further- 
 more, they render it unnecessary to entirely remove the nut 
 as is done on some of the bolts near the hinge. However, by 
 proper design this objection can be remedied on the hinged 
 door. 
 
 Retort Lagging. — Practice in regard to lagging or covering 
 the retorts to prevent heat losses due to radiation varies widely. 
 In northern plants where fuel is high and outside temperature 
 at times very low, several plants have covered their retorts and 
 tanks and secured very good results. The chief objection to 
 covering retorts is the expense and trouble in case of cylinder 
 leaks. I;t is common practice, however, to lag all steam pipes. 
 Most plants use exhaust steam to heat these various tanks and 
 consider the lagging of the retort unnecessary. It is the author's 
 opinion that lagging is desirable and if properly applied will more 
 
96 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 than pay for itself in a few years. Mr. R. W. Yarborough con- 
 tributed an interesting paper on this subject at the 1911 con- 
 vention of the Wood Preservers' Association. Mr. Yarborough 
 roughly estimated that about 2,000,000 B.T.Us. were lost per 
 hour in operating a retort 7 feet X 132 feet, which is equivalent to 
 the consumption of about 187 pounds of coal. "With coal at $3 
 per ton, this represents a loss of about 30 cents per hour, or $2.40 
 per 8-hour day. It costs about $300 to $1200 to cover a 
 7 foot X 132 foot retort, depending upon the kind of lagging used. 
 Most any fibrous material which is a poor heat conductor can 
 be employed. Cheap coverings can be made according to the 
 following: (1) Sawdust and starch re-enforced with poultry wire, 
 (2) cotton seed hulls, (3) mixture in equal parts of lime, sawdust, 
 and asbestos, (4) sawdust, tar felt, and wood slats. 
 
 The Pump House or Room. — It is highiy desirable to have the 
 pumping Machinery as close to the retorts as possible, as this 
 avoids unnecessary piping and renders the operation more accur- 
 ate and less troublesome. (See Plate IX, Fig. D.) In best practice 
 this is accomplished by either building the pump house adjoining 
 the retort house or placing the machinery in the retort house and 
 separating it from the retorts by means of a fire wall or partition. 
 Fumes arising from the cylinders are thus confined to the retort 
 house. In the pump house are installed the force pumps for 
 moving the preservatives, vacuum pumps, compressed-air 
 pumps, fire pumps, and at times electrical equipment in case the 
 plant is to operate at night. Gauges for recording temperature, 
 pressure, and vacuum in the retorts are also frequently installed 
 here, as well as the devices for measuring the absorption and 
 consumption of the preservative in the retorts and measuring 
 tanks. The arrangement of this apparatus is one of the most 
 important features in designing a wood preserving plant. It is 
 very essential to use only high-grade machinery and then, if 
 funds permit, provide for duplicate units. Cheap pumps and 
 rigid units always result in troublesome delays and repairs, mak- 
 ing good work almost an impossibility. Machinery made by 
 any high-grade concern can, however, be used, its selection being 
 largely a matter of personal taste. Rubber gaskets should not 
 be permitted if they are likely to come in contact with creosote. 
 Likewise, if zinc chloride is to be used the pumping parts should 
 be so constructed that they will not be corroded too rapidly 
 and hence cause the pumps to work unsatisfactorily. It is es- 
 
Plate IX 
 
 Fig. a. — The construction of the collar and door in a pressure cylinder. 
 Note cylinder track and guard rails. (Photo courtesy of the Allis Chalmers 
 Co.) 
 
 Fig. B. — Construction of a door with cast steel rim and dished plate steel 
 head. (Photo, through courtesy of the Allis Chalmers Mfg. Co.) 
 
 {Facing page 96.) 
 
Plate IX 
 
 Fig. C. — Cylinder doors without hinges. Norfolk Creosoting Company. 
 (Forest Service photo.) 
 
 Fig. D. — Pump room C. B. & Q. R. R. treating plant, 
 gauges and control valves. 
 
 Note arrangement 
 
OPERATION OF WOOD PRESERVING PLANTS 97 
 
 sential also to have pumps of such design that the packing and 
 working parts can be easily inspected and replaced. Either 
 wet or dry vacuum pmnps may be used. If the latter, a surface 
 condenser will be found advantageous. Some plants have done 
 away entirely with force pumps in moving the preservative and 
 applying pressure in the retorts by using compressed air. The 
 author's experience with such equipment has shown it to be 
 highly satisfactory, as it is quick, efficient, and cleans the pipes 
 thoroughly. Care should be taken, however, to prevent an 
 emulsifying of the oil, especially if it contains much water. In 
 fact, it is good policy to so design the plant that the oil can be 
 transferred with a minimum of agitation. 
 
 According to Mr. F. J. Angier, the advantages of the air- 
 pumping, system, over the hydraulic system are:^ 
 
 "Only one tank is required for each retort, that tank serving in the 
 triple capacity of pressure tank, measuring tank, and drain tank. 
 
 One air pmrip is ample for three retorts, while one hydraulic pump is 
 required for each retort. 
 
 The maintenance of one air pump is much less than three hydrau- 
 lic pumps, and is decidedly cleaner. The air pump requires less at- 
 tention, and lessens the cost of packing, lubricants, valves, valve seats, 
 plungers, etc. 
 
 An air pump is a necessity in plants using hydraulic pumps for blowing 
 back solution, unless those plants are equipped with expensive under- 
 ground receiving tanks. In the latter case an air pump can be dispensed 
 with in lieu of a large oil pump for pumping solution back into the work- 
 ing tank. The underground receiving tank is more expensive in opera- 
 tion than the air pump, and no doubt this is the reason why so few plants 
 are thus equipped. 
 
 One air pump can be operated on two or more retorts at the same time 
 without deranging the gauge readings. This is not practicable with 
 hydraulic pumps. 
 
 Experience has taught us that it is practically impossible to maintain a 
 steady and constant pressin-e on a charge of timber with a hydraulic 
 pump, even though it is equipped with reUef valves, while with the air 
 pump this is easily accomplished. 
 
 The amount of steam required to operate one air pump is not more 
 than would be required to operate three hydraulic pumps, but as 
 the exhaust steam is used for heating purposes, this feature is not so 
 important. 
 
 The initial cost of instaUing the air-pump system is a trifle more than 
 
 ' F. J. Angier, Proceedings American Wood Preservers' Ass'n., 1914. 
 7 
 
98 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 for the hydraulic pump system, but the maintenance is less, and in the 
 long run air is more economical. The following statement will give some 
 idea of the relative first cost, which may vary one way or the other, 
 depending on local conditions: 
 
 Cost op Air-pump System 
 One air pump (capacity 8 cubic feet of compressed air per 
 
 minute at 175 pounds gauge pressure) $1200.00 
 
 Three pressure-measuring-drain tanks 2000 . 00 
 
 Piping, valves, etc. (estimated) 400. 00 
 
 Total cost of airnydraulic-pump system $3600 . 00 
 
 Cost of Htdeaulic Pump System 
 
 Three hydraulic pumps $1000.00 
 
 Three measuring tanks 900 . 00 
 
 Two drain tanks 400. 00 
 
 One low-pressure air pump 500 . 00 
 
 Piping, valves, etc. (estimated) 600. 00 
 
 Total cost of hydraulic-pump system $3400 .00 
 
 With hydraulic pumps there is more machinery to care for, more 
 tanks to look after, and more piping and valves to maintain. There is 
 also more work for the engineer, and unless everything is compactly 
 arranged the engineer will require an assistant. With the air pump one 
 man can easily look after the entire operation with greater satisfaction 
 and with better results." 
 
 The Machine Shop or Room. — This may be an independent 
 building or a room adjoining the retort house, but in either case is 
 a very important element in a pressure preserving plant, espe- 
 cially if the plant is remotely situated. In addition to hammers, 
 chisels, wrenches, etc., it is very desirable to have a good forge, 
 especially for repairing cylinder cars. If the plant is large a lathe 
 will also be found handy. Too much attention cannot be paid to 
 a good pipe-fitting outfit, and only clean, sharp dies should be 
 permitted about the plant. 
 
 The Boiler House. — As a precaution against fire, the boiler 
 house should be a separate building situated some distance from 
 the treating plant proper. There is nothing novel about the 
 construction of the boiler house. A common mistake, however, is 
 to underestimate boiler capacity, especially where steaming is 
 practised and low temperatures are encountered. A good ratio 
 is about 160 H.P. to a cylinder 7 feet in diameter X 132 feet in 
 length with a working pressure of 125 pounds. 
 
OPERATION OF WOOD PRESERVING PLANTS 99 
 
 Yard. — The yard arrangement is one of the most important 
 features of a wood preserving plant. (See PlateX, Fig. A.) To 
 have the yard designed in a flexible manner so any point can be 
 easily reached without unnecessary distance, to economize in track 
 equipment, to allow proper storage for the timber, and ];eady 
 means of loading and unloading it is not a problem easy of solu- 
 tion. Many yards are poorly designed, resulting in an unnec- 
 essary initial expenditure and excessive operating costs. While 
 the yard layout will vary considerably depending upon the re- 
 quirements peculiar to each plant, certain general essentials 
 applicable to all yards can be given. 
 
 In the first place, the yard should be level, well drained, free 
 from rank vegetation, and if possible covered with cinders. The 
 timber should be piled off the ground at least 8 inches, preferably on 
 creosoted stringers, with sufficient space between the piles to allow 
 a free circulation of air and ready inspection. No decayed wood 
 about the yard should be tolerated. 
 
 The track should be well constructed, with good bearing for 
 each tie, properly spaced, in perfect alignment, and even grades. 
 The rail should not be too light but should run 60 pounds or over. 
 To use a very light rail or old rail badly worn or pitted is poor 
 economy. So far as possible the track should be straight and 
 sharp curves avoided. A good working distance between tracks, 
 center to center, is 50 to 70 feet. If the plant is to handle 
 several forms of timber, especially piling, poles, and long dimen- 
 sion stock, the use of 3-rail track for standard and narrow 
 gauge is satisfactory and economical but liable to cause delays. 
 If only ties are to be treated, a narrow gauge in the yard proper 
 is sufiicient, standard gauge being used only to tap the main 
 centers of distribution. The number of frogs and crossovers 
 should be kept to a minimum, but should allow sufficient flex- 
 ibility in moving trams or cars. The use of a transfer table has 
 been suggested by Mr. W. F. Goltra in order to keep the number 
 of switches to a minimum. There appears much merit in this 
 scheme. A yard arrangment for a tie plant is shown in Fig. 10. 
 
 Loading Dock. — If the plant is to handle large numbers of ties, 
 a loading dock will be found very useful, especially if the plant re- 
 ceives mostly flat cars or gondolas and the ties are loaded by 
 hand. The dimensions of the loading dock will vary, of course, 
 with the size of the plant, but it should have an elevation at 
 least equal to the height of the floor in freight cars. A loading 
 
100 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 dock for ties is shown in Plate X, Fig- B. The loading dock 
 enables the foreman to easily keep his workmen in view. 
 
 Methods of Transferring Material in the Yard. — Practice 
 varies and opinions differ concerning the best method of handling 
 timber in the yard. The tram or cylinder cars are moved in four 
 ways: by cables, dummy engines, electric locomotives, and by 
 horses or mules. For tie plants where the yard arrangement can 
 be simplified, electric locomotives are very satisfactory. For 
 general all-around work the dummy engine is satisfactory, as it 
 is inexpensive, flexible, and eflicient. If properly handled it offers 
 no unusual fire risk. When labor is avialable, loading and un- 
 loading ties by hand is still best practice, especially when it can 
 be done by piece work. Some plants, however, use the locomo- 
 tive crane moving a whole buggy load of ties at a time. (See Plate 
 X, Fig. C .) For timbers which are too heavy to be moved by hand 
 the author prefers the locomotive crane to any other system, large- 
 ly because of its efliciency and fiexibility. Stationary derricks 
 operated by cables are also satisfactory for heavy timbers, but 
 have not the radius of action of the locomotive crane. ' Traveling 
 cranes are also used by some plants but like the derrick are limited 
 in their territory. Furthermore, unless the structures on which 
 they run are properly braced and mounted on solid foundations, 
 they will get out of alignment and cause trouble. In a few treat- 
 ing plants small canals filled with water run through the yard. 
 The heavy timbers are rolled off skids into these canals and 
 floated to the retort house, where they are placed on the cylinder 
 cars by a traveling crane. (See Plate X, Fig. D.) A few coast plants 
 store their heavy timbers as rafts in water — a method which of 
 courseprecludes any air seasoning. 
 
 Cylinder Cars. — These are also referred to as tram cars, bolster 
 cars, retort cars, and "buggies." Three general types are gen- 
 erally recognized: (1) a tie car of rigid construction throughout, 
 (2) a swivel or bolster car which has a pivot bearing to allow for 
 long timbers in rounding curve, and (3) a block car for holding pav- 
 ing blocks. Two of these types are shown in Plate XI, Fig. A, and 
 Fig. B. There are two essential features in the proper building of all 
 types, which are often sadly neglected, viz., a heavy, substantial 
 construction and a maximum holding capacity. On account of 
 the severe usage to which the cars are put, they should be made very 
 strong or they will soon be broken or bent and consigned either to 
 ^he repair shop or scrap heap. Especial attention should be given 
 
Plate X 
 
 Fig. a. — Chicago and Northwestern Tie Treating Plant, Escanaba, Mich. 
 (Photo through courtesy C. & N. W. R. R..) 
 
 Fig. B. — Tie treating plant of the Pennsylvania R. R. Note concrete 
 loading dock with empty cylinder cars on top, also manner of unloading 
 and pUing ties for air seasoning. (Photo through courtesy of the P. R. R.) 
 
 (Facing page 100.) 
 
Plate X 
 
 Fig. C. — Unloading treated ties from cylinder buggies into gondolas 
 with a locomotive crane. Port Reading Creosoting Co. (Forest Service 
 photo.) 
 
 Fig. D. — Overhead electric crane for loading timber into cylinder cars 
 Gulfport Creosoting Co., Gulfport, Miss. 
 
OPERATION OF WOOD PRESERVING PLANTS 101 
 
 to properly reenforcing the curved arms so they will not bend and 
 jam in the cylinder. The frame work should also be set low or 
 the treating capacity of the plant will be greatly decreased. A 
 solid iron hoop or " bail " is preferred to chains, in order to hold the 
 timbers on the car, and no jamming or pounding of the bails 
 should be tolerated. It is almost universal practice to build the 
 cars without couplers, the idea being to save expense, time and 
 space in the cylinder. Hence the cars must always be pushed 
 and never pulled. Some plants broke away from this practice and 
 used couplers on their cars so they could be pulled as well as 
 pushed — a scheme which has been prohibited in certain states 
 because of danger to workmen. Block cars can be made out of 
 tie cars by simply placing on the tie car a perforated sheet-iron 
 basket with hinged doors. In some cases the cars are built 
 purposely for handling blocks and so designed that they can be 
 emptied by lifting them bodily with a locomotive crane and turn- 
 ing them upside down. 
 
 A good feature in the design of cylinder cars is to have loose 
 wheels of heavy construction fitted with roller bearings and a 
 fairly wide tread. 
 
 Measuring, Mixing, Working, and Storage Tanks. — A meas- 
 uring tank is one used for measuring the absorption of pre- 
 servative forced into the wood. It is invariably constructed of 
 steel. It is considered good practice to have the diameter of these 
 tanks as small as possible in order to allow for an accurate reading 
 of the preservative and to have them accurately calibrated. 
 Furthermore, they should be placed as close to the retorts as 
 proper design will permit. Some engineers have carried this 
 idea as far as to place them directly over the retorts. The size 
 of the measuring tanks in relation to the size of the retort varies 
 greatly in practice. In some plants the volume of the measuring 
 tanks is 1 1/2 times the volume of the cylinder, in others it is less 
 than half the volume of the cylinder. In most plants these 
 tanks are built to withstand the pressure due to only the head 
 of the preservative, and are elevated upon stationary platforms 
 so that the preservative can flow from them into the retorts 
 by gravity. In a few plants, using compressed air, the meas- 
 uring tanks are mounted on the ground and built to withstand 
 a working pressure equal to that of the retorts. Another design 
 mounts the measuring tanks upon scales so that as the preservative 
 is pumped out of them through flexible connections the amount 
 
102 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 of preservative forced into the retorts can be read directly. All 
 float gauges are in this case done away with. The author prefers 
 the two latter designs of constructing tanks of this kind. 
 
 Mixing tanks are used for making solutions of zinc chloride. 
 A substantial construction is to use wood lined with lead. Con- 
 centrated solutions of zinc chloride are basic and will attack 
 wood. If tar is mixed with creosote the 'ta^ks in which this is 
 done are also sometimes called "mixing tanks" and are generally 
 built of steel. 
 
 Working tanks are intermediate in size to measuring and stor- 
 age tanks and are in common use. They are not used to measure 
 absorption but to aid the measuring tanks in filling the retorts 
 with preservative. In other words, after the wood has been 
 placed in the retorts and the doors locked, the preservative is 
 run from the working tank until the retort is filled, after which 
 the preservative is drawn from the measuring tank. Working 
 tanks are usually built of steel and elevated so that the pre- 
 servative can run from them into the retorts by gravity. If zinc 
 chloride is used, the tanks are frequently built of wood, as weak 
 solutions of zinc chloride will attack steel. In some plants 
 working tanks are not used, in which case the measuring tanks 
 are made with larger capacity. Working tanks may have from 
 about 1 to 3 times the capacity of the retorts. 
 
 Storage tanks, as the name implies, are used to store the 
 preservative. Therd is no agreement as to size, this depending 
 upon the requirements of each plant. They are generally located 
 some distance from the plant proper as a matter of safety. It is 
 well to have the storage tanks at least sufficiently large to allow 
 for a month's supply when operating at full capacity. On account 
 of their large size, storage tanks are frequently built without a 
 roof, evaporation of oil being retarded by means of a water seal. 
 Generally the measuring and working tanks are covered. 
 
 Some plants are equipped with receiving tanks, which are 
 buried below ground so that the excess preservative in the retorts 
 can be drained into them, after which it is pumped back into the 
 working or measuring tanks. This enables a quick emptying of 
 the cylinders. When the excess preservative is pumped or 
 blown back from the cylinders, these tanks are unnecessary. 
 
 Because creosote congeals at low temperatures, all of the 
 tanks described are generally fitted with steam coils through, 
 which exhaust or live steam may be passed. Traps should be 
 
Plate XI 
 
 Fig. a. — Bolster Car. Used for long timbers. (Photo through courtesy 
 of the Allis Chalmers Mfg. Co.) 
 
 Fig. B. — A tie car. (Photo through courtesy of the Allis Chalmers 
 
 Mfg. Co.) 
 
 {Facing page 102.) 
 
Plate XI 
 
 Fig. C. — Mercury gauge for measuring the preservative in the measuring 
 tank. Baltimore & Ohio R. R. Tie Plant. (Photo through courtesy of 
 the B. &0. R. R.) 
 
 Pig. D. — Wood Block treating plant of the Chicago Creosoting Co., Terra 
 Haute, Ind. Note vertical cylinders. (Photo through courtesy of the 
 Chicago Creosoting Co.) 
 
OPERATION OF WOOD PRESERVING PLANTS 103, 
 
 coupled to the exhaust ends of all these coils. Air is at times 
 passed through the storage tanks in order to keep the composition 
 of the preservative uniform. 
 
 Gauges and Scales.— Many plants are still careless in their 
 methods of measuring absorptions of preservative. Of course, if 
 the plant is doing its own work, as in most railroad plants, 
 accurate measurements of absorption are not as essential as in 
 commercial plants treating on contract. However, in either 
 case, correct determinations are at least desirable. Several 
 methods of measuring absorption are in practice. The most 
 common is to have a float and tell-tale sliding on a vertical scale 
 board, the two connected by a chain or fine piano or annealed wire 
 which runs over pulleys. If the float, tell-tale, and pulleys are 
 large, operating with little friction, the scale board accurately 
 calibrated, the chain or wire protected from' the wind, and the 
 preservative, if an oil, corrected for temperature expansion, this 
 method is simple and gives satisfactory results. Care should be 
 taken to agitate the preservative as little as possible in pumping 
 or blowing back. 
 
 When compressed air is forced into the top of the measuring 
 tank the total absorption may be determined by gauge glasses 
 or pet cock fastened to it, and a check on the total amount made 
 after the excess preservative has been pumped or blown back 
 from the retort. 
 
 If the measuring tank is mounted on a scale, the absorption 
 may be read directly from the scale beam in pounds. This 
 renders corrections for temperature expansion unnecessary in the 
 measuring tank. Another excellent device is to use a mercury 
 column set at an angle to the desired degree of sensitiveness. 
 (See Plate XI, Fig. C.) Readings in pounds can thus be directly 
 and accurately obtained. Care should be taken to keep the oil in 
 the gauge pipes liquid and free from air. A very good check on 
 the methods just described is to weigh the timber on track scales 
 before it goes into the retorts and immediately after it comes 
 out. This, doubtless, is the most accurate way of determining 
 absorption. It cannot be used, however, if the timber is steamed 
 or boiled in oil while in the retort, as such treatments change the 
 weight of the untreated wood. It is by no means easy to measure 
 accurately the amount of preservative the charge of wood is 
 absorbing, especially during treatment, and this is largely a 
 matter dependent upon the skill of the operator. A very im- 
 
104 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 portant aid in gauging absorption is to have accurate ther- 
 mometers in all tanks used during the treatment. 
 
 Piping. — The importance of using sharp, clean threads in mak- 
 ing pipe connections has already been emphasized. Too much 
 emphasis cannot be laid upon this detail. It is also highly- 
 desirable to make all pipe lines — especially those for trans- 
 ferring oil — as short as possible, and to provide a system 
 whereby then can be completely drained, with a sump if neces- 
 sary. Otherwise, trouble may be experienced with the oil con- 
 gealing in the pipes. Another essential is to use only high-grade 
 gate valves with replaceable wearing parts in all lines for trans- 
 ferring liquid, and to pack these with material not attacked by the 
 preservative. A precaution against leaks or breakage is to have 
 duplicate valves in all important lines. As considerable dirt, 
 pieces, of bark, etc., fall from the timber, all lines transferring pre- 
 servative from the retorts should be protected with perforated 
 plates or screens. A "mud drum" placed below the retorts is a 
 good prucaution. If these safeguards are not taken, the valves run 
 a decided risk of being either damaged or destroyed. 
 
 Shower Baths. — Under best operating conditions a wood-pre- 
 serving plant is none too clean a place for workmen. Those 
 companies which have installed locker rooms and shower baths 
 for their men have found their investment a paying one. Since 
 these can be installed at small expense, they are recommended. 
 
 Inspector's Laboratory. — Too frequently an inspector's or 
 chemical laboratory is either omitted entirely, or when an at- 
 tempt is made to furnish one, it is a good place to avoid. This 
 is bad business policy, as the most progressive companies have 
 discovered. While, of course, an elaborate outfit is not neces- 
 sary, the place should be clean, well lighted, comfortable, and 
 equipped with proper apparatus. In brief, the inspector's 
 laboratory should contain a detailed map of the plant, showing 
 all valves and pipe lines, with tables giving the dimensions of all 
 essential plant units. It should have tools, such as rules, tapes, 
 a brace and bit, saws, and hatchets, for studying the penetra- 
 tions, and standard tables for ready reference; apparatus and 
 chemicals for analyzing the preservatiye, including retorts, 
 flasks, beakers, pipettes, hydrometers, etc., and a chemical 
 balance. While not absolutely necessary, a drying oven for 
 studying moisture in wood and a refractometer for studying 
 oils will also be found helpful. Samples of wood properly iden- 
 
OPERATION OF WOOD PRESERVING PLANTS 105 
 
 tified as to kinds and showing proper treatment will also be found 
 valuable. Some companies have not only equipped their plants 
 with such laboratories, but have furnished a small experimental 
 plant. Unfortunately, the press of daily routine almost in- 
 variably prevents the operators from carrying on experiments 
 in them. 
 
 Fire Protection. — The best fire protection lies in proper pre- 
 vention through wise design and efficient operation. Under 
 such conditions danger from fire is very slight. However, as 
 added precaution and to meet underwriters' requirements, a 
 good fire pump is highly desirable. In addition, the water stor- 
 age tank can be drawn upon. Fire hydrants should also be in- 
 stalled in the yard and properly maintained. Some plants leave 
 fire lanes between the piles of timber 30 or more feet in width. 
 Boxes of sand protected against rain and equipped with shovels 
 are an excellent safety factor, as well as hand chemical extin- 
 guishers hung at vital points in the plant. 
 
 Lighting Equipment. — As the plants are often called upon to 
 run at night, the dynamos should be sufficiently powerful to not 
 only light the plant proper but also arc lights in the yard. As a 
 general rule, however, loading and unloading of material should 
 be confined as much as possible to the daytime, leaving only the 
 treatments for night work. 
 
 Sawmill and Block Equipment. — Several wood-preserving 
 plants in the United States are equipped with small sawmills to 
 frame their timbers before treatment. The framing of such tim- 
 bers before the preservative is injected is good practice, as it 
 insures a protection to the wood over its entire surface. In fact, 
 ideal practice would be to have the timber framed to the exact 
 dimensions required so that no cutting or boring would be re- 
 quired after it has been treated. There is nothing novel about the 
 construction or operation of these sawmills. They can be located 
 at any convenient place in the yard and, as a matter of safety, 
 some distance from the treating plant. 
 
 The manufacture of wood blocks is almost invariably done in 
 connection with the treating plant, the timber being received in 
 planks and sawed into the various sizes of blocks required. 
 The planks are carried by chain conveyors to the saws, 
 which are spaced so as to cut them into the desired depth of 
 block. In some plants the saws are all arranged on the same axis 
 and the blocks all cut at one time. In others the planks are first 
 
106 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 cut into smaller planks, which are in turn cut into blocks, it being 
 claimed that this economizes in wood consumption, as knots, etc., 
 can be trimmed with least waste. The blocks then fall from the 
 saws onto a conveyor, which either carries them to a bin, or, 
 preferably, direct to the cylinder cars, into which they are dumped 
 by gravity. A good design is to have the cylinder cars on a track 
 paralleling the block conveyor. As the blocks are carried along 
 the conveyor they can be inspected and all defective blocks re- 
 moved. By having small swinging gates along the side of the 
 conveyor, the operator can open one, using it to deflect the blocks 
 into the cylinder car below, and after this has been filled, close 
 the gate and open the next one situated further on, thus deflecting 
 the blocks into the second car, and so on until the entire charge 
 is filled. This method works very efiiciently and minimizes 
 labor. The rate at which the blocks can be manufactured varies, 
 of course, upon the size and speed of the machine and depth to 
 which the blocks are cut. A good machine, however, should 
 turn out 200 square yards of 4-inch, blocks per hour. 
 
 The Chicago Creosoting Company has recently taken out pat- 
 ents on a new type of plant for treating paving blocks which does 
 away entirely with cylinder cars and enables a decreased cost in 
 operation. Their cylinders, which are 11 feet in diameter and 14 
 feet high, are built vertical, the blocks being carried on a con- 
 veyor and dumped automatically into the cylinder. The treat- 
 ment is then conducted in the usual manner, after which the 
 door in the bottom of the retort is opened and the blocks fall 
 directly into cars for shipment. (See Plate XI, Fig. D.) 
 
 Tie-boring and Adzing Machines. — At present few treating 
 plants consider tie-boring and adzing machines as a fixed part 
 of their equipment. There is no doubt but what such machines 
 are a desirable asset to any plant which is treating large quantities 
 of ties, and that they will be viewed with increasing favor because 
 of the excellent results secured from them. These machines at 
 present are generally mounted upon a portable platform such as 
 an improvised box car and are driven by a gas engine. (See 
 Plate XII, Fig. A-Plate XII, Fig. B.) The rough ties are placed 
 on a conveyor which automatically passes the ties through the 
 machine, where they are adzed and bored. Other attachments 
 are sometimes used, such as a device for trimming the ties to exact 
 length, and a die or punch which brands them on the ends, this 
 giving the date, kind of treatment or species of wood. The ties 
 
Plate XII 
 
 Fig. a. — Ties entering boring and adzing machine. (Photo through cour- 
 tesy of the Greenlee Bros. Co.) 
 
 ^^ 
 
 7 
 
 
 '''- ' ■' ' OP'^^'^I 
 
 Pjq b. — Ties adzed and bored being piled on the cylinder cars ready for 
 treatment. (Photo through courtesy of the Greenslee Bros. Co.) 
 
 (Facing page 106.) 
 
Plate XII 
 
 Fig. C. — Section through an oak tie showing a cut and screw spike 
 driven in place. Note comparative distortion of wood fibers. (Photo 
 through courtesy of the Spencer-Otis Co.) 
 
OPERATION OF WOOD PRESERVING PLANTS 107 
 
 then pass down a conveyor on the opposite side of the car, where 
 they are piled either in stacks or directly upon cylinder cars for 
 treatment. The capacity of these machines varies but averages 
 about 3000 ties per 10-hour day. The advantages of such treat- 
 ment are given in greater detail in Chapter VIII. The total cost 
 of adzing and boring ties varies from about 1 1/4 to 2 cents each. 
 
 The Operation of Pressure Plants. — The operation of pressure 
 wood-preserving plants varies widely, depending upon local 
 conditions, the opinion of the engineer in charge, and the proc- 
 esses used. The latter have been described in detail in Chapter V 
 but we will discuss here the effect of the various manipulations 
 more or less common to all plants. Unfortunately, the amount 
 of exact data available is very meager, and results are often se- 
 cured without knowing why; hence the success or failure of a treat- 
 ment depends very largely upon the experience of the operator. 
 
 The Effect of Vacuum. — A vacuum may be drawn in the treat- 
 ing cylinder before the preservative is admitted, or after the pre- 
 servativej has been forced into the timber, or both before and 
 after. When drawn before admission of preservative, it is re- 
 ferred to^as a "preliminary vacuum." If drawn after injection 
 it is called a "final vacuum." 
 
 As staged in Chapter IV, a preliminary vacuum drawn imme- 
 diately after the timber has been steamed helps to dry the timber. 
 The reduced pressure in the cylinder lowers the boiling point of 
 water arid hence hastens the rate with which it evaporates. 
 When a |)reliminary vacuum is drawn on air-seasoned wood it 
 also tend,s to slightly dry the wood and remove an appreciable 
 amount of air from it. If, now, the preservative is admitted to 
 the cylinder without breaking the vacuum, the speed with which 
 the cylinder fills is increased. Furthermore, the preservative 
 can usually be forced into the wood in a shorter time and with 
 less difficulty. But the most noticeable effect is the manner in 
 which the preservative is held in the wood after the pressure is 
 released (Fig. 11). It will be noticed that only a comparatively 
 small amount of it rebounds or drips from the timber. The 
 absence of large amounts of air in the wood cells is undoubtedly 
 the cause of this, since on the release of pressure there is not suf- 
 ficient expansion of this air in the wood to force out much of the 
 preserving fluid. In order to leave the greatest amount of 
 preservative in a given stick of timber, therefore, a preliminary 
 vacuum should be used. This fact is of prime importance in 
 
JO 
 
 108 THE PRESERVATION OF STRUCTURAL TIMBER 
 
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 retained in them. 
 
OPERATION OF WOOD PRESERVING PLANTS 109 
 
 treating timbers which are resistant to absorption or when 
 large absorptions are desired. The greater the intensity of the 
 vacuum, the better will be this result, and, if possible, at least 26 
 inches should be obtained. The length of time the vacuum should 
 be held depends chiefly upon the kind and size of timber being 
 treated. Porous woods like maple and red oak require a shorter 
 vacuum period than resistant woods like hemlock and tamarack. 
 Small size timbers require a shorter vacuum period than large 
 size. Exact periods for all species and sizes of wood are not 
 definitely known. Some attempts to secure data on the rate at 
 which a vacuum ban be drawn on the interior of air-seasoned 
 ties were made at the U. S. Forest Products Laboratory by boring 
 a hole to the center of the tie and inserting a small pipe connected 
 with a vacuum gauge fastened to the shell of the cylinder, 
 and thus drawing a vacuum in the cylinder. It was found that 
 in the porous woods like red oak the vacuum on the inside ap- 
 proached that on the outside much more rapidly than in the more 
 resistant woods like hemlock. Of course, it is not necessary to 
 secure as great a vacuum in the center of timber as in the outside, 
 because the preservative can rarely be forced to the center, espe- 
 cially in large-sized sticks, but the closer this can be obtained, the 
 more beneficial will be the results. 
 
 To sum up the effect of a preliminary vacuum : 
 
 1. More preservative is absorbed during the filling of the cylinder than 
 when no prehminary vacuum is used (Fig. 12). This is especially true in 
 porous woods like loblolly pine. 
 
 2. It reduces the length of time pressure must be held in the cyhnder in 
 order to secure the desired absorption. This difference is apparently very 
 slight in woods of moderate porosity like maple, but considerable in porous 
 or resistant woods Uke lobloUy pine or hemlock (Fig. 12). 
 
 3. It reduces to a minimum the rebound or "kickback" of the preserva- 
 tive on the release of pressure in the cylinder (Fig. 12). 
 
 4. It reduces to a minimum the amount of drip (Fig. 12). 
 
 5. It enables very heavy absorptions to be more easily obtained. 
 
 6. It tends to produce very unequal penetrations and absorptions if only 
 small amounts of preservative are forced into wood and hence should not be 
 used in such cases. 
 
 A final vacuum produces the opposite effect of a preliminary 
 vacuum in that it tends to remove the preservative from the wood. 
 It is greatly aided in doing this if air is left in the wood or if the 
 wood is treated with compressed air before the preservative is 
 admitted. The vacuum causes this air to expand and force out 
 
110 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 ^ooj siqtiO xaO. spunoj -noi^djosqy 
 
OPERATION OF WOOD PRESERVING PLANTS 
 
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112 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 the preservative. A final vacuum is drawn either to dry the 
 timber and thus reduce loss of preservative through drip, or to 
 withdraw a portion of the preservative (see description of " empty- 
 cell" processes), or to do both. In the tests referred to above, a 
 final vacuum was drawn on some of the ties and its effect in re- 
 covering creosote is shown in Figs. 13 and 14. In these tests 
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 than when no final vacuum was drawn, being greatest in woods 
 easily treated and least in those which are resistant to injection. 
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 Fig. 14. — Showing the effect of air in ties upon the "kickback" with creosote. 
 
 To sum up the effect of a final vacuum : 
 
 1. It dries the ties. and hence reduces drip (Fig. 13), 
 
 2. It removes some of the preservative injected into the ties, although 
 this, in itself, is apparently not great, but may be appreciable if used in con- 
 nection with a preliminary or atmospheric air pressure (Figs. 13 and 15). 
 
 The Effect of Air Pressure-— Air pressure is used either before 
 or after the preservative is forced into the wood; hence, as with 
 the vacuum, we have ''preliminary" and ''final" air pressures. 
 
 Preliminary air pressures ^re used to force a portion of the 
 preservative out of the wood and hence give an "empty ceir* 
 
OPERATION OF WOOD PRESERVING PLANTS 
 
 113 
 
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 Fig. 15. — Showing the effect of air in ties upon the amount of creosote 
 recovered by a final vacuum and drip. 
 
 and the pressure on the preservative is then released, the air in 
 the wood will expand and force out a part of the preservative. 
 Some data on the amount thus forced out is shown in Pigs. 12 
 and 13. It will be noted that the amount of air forced out varies, 
 
 8 
 
114 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 up to a certain ratio, with the amount of air forced into the wood, 
 and that a final vacuum increases this amount (Fig. 15). It has 
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 a long time to escape — several days in some cases — and that this 
 causes either a large drip or volatilization of preservative or both. 
 
 The effect of a preliminary air pressure is, then, to : 
 
 1. Increase the amount of preservative absorbed during the filling of the 
 
OPERATION OF WOOD PRESERVING PLANTS 115 
 
 cylinder over what is absorbed when only atmospheric pressure is used 
 (Fig. 16). 
 
 2. Increase the length of time pressure must be held on the preservative in 
 order to obtain the desired absorption. This is but sUght, however, in 
 woods like red oak but considerable in resistant woods like hemlock (Fig. 
 12). 
 
 3. Increase the amount of preservative which rebounds or "kickback" 
 from the wood on release of pressure (Fig. 12). 
 
 4. Increase the amount of drip (Figs. 12, 13). 
 
 5. Leave a minimum amount of preservative in the wood (Fig. 14). 
 
 A "final air pressure" is seldom used. It was originally ad- 
 vocated to force the preservative deeper into the wood and thus 
 produce an "empty-cell" effect. While it tends to do this to a 
 slight extent, nevertheless it exerts a more pronounced action 
 in removing some of the preservative. This is probably due to 
 the fact that when pressure is released the air escapes from the 
 wood and carries some of the preservative with it. 
 
 The Effect of Pressure on the Preservative. — In applying 
 pressure to a preservative in a treating cylinder three factors are 
 of importance: The intensity of the pressure, the duration of 
 the pressure, and the rate at which the pressure is applied. 
 
 In general, the higher the pressure the greater and more rapid 
 the penetration. On porous woods, high pressures are not neces- 
 sary and, in fact, often objectionable because they force the pre- 
 servative too rapidly into the wood and cause irregular penetra- 
 tions. With resistant woods, high pressures (175 pounds per 
 square inch or over) are also of little value because the resistance 
 of the wood is often so great that the application of excessive pres- 
 sure — even 500 pounds per square inch or more — is not suffi- 
 cient to overcome this resistance. Working pressures of from 
 100 to 150 pounds per square inch give most general satisfaction. 
 
 As the wood cells are minute and the channels through which 
 the large portion of the preservative passes are frequently micro- 
 scopic in size, it is necessary to allow sufficient time for the pre- 
 servative to diffuse through them. If the desired absorption 
 of preservative is secured in a short period, the penetration is 
 apt to be very irregular, whereas if the same absorption is ob- 
 tained in a longer period a more uniform distribution is generally 
 secured. The ideal result is to have the preservative diffused 
 through the wood uniformly and deeply. The application of a 
 lower pressure held for a longer time approaches this result better 
 than a high pressure held for a short time. Its chief disadvantage 
 
116 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 is a decrease in the capacity of the plant. The rate at which the 
 pressure is appUed to the preservative is also important. If it is 
 applied rapidly up to the maximum, and the maximum is high, 
 the desired absorption will be obtained in the shortest time but 
 at the expense of greatest diffusion. A rapid application of 
 pressure with a comparatively low maximum is better practice. 
 If, however, the operator wants capacity, and a large rebound or 
 "kickback" of preservative after the pressure is released, a 
 rapid application of high pressure is the thing to use. The erratic 
 penetration due to a quick absorption may be compensated for, 
 in part at least, if the operator forces into the wood more pre- 
 servative than he intends to leave in it, and counts upon the 
 "kickback" to remove the surplus preservative. As has been 
 shown above, the condition of the air in the timber also produces 
 a marked effect upon the amount of preservative which rebounds 
 out of the wood when pressure is released. 
 
 Some Common Errors and Difficulties in Operating Pressure 
 Plants. — Even in the best equipped and managed plants, mechan- 
 ical errors and difficulties in operation are almost daily encoun- 
 tered. Without going into the details characteristic of each proc- 
 ess, the following general notes may be found of service, particu- 
 larly to operators and inspectors. 
 
 Difficulty of Measuring Volume of Charge. — The volume of 
 the timber in the treating cylinder could easily be determined, 
 irrespective of its form, by subtracting the quantity of preserva- 
 tive it takes to fill the cylinder when charged from that necessary 
 to fill it when empty, and deducting the volume of the cars, were 
 it not for the fact that the wood will absorb the preservative 
 while the cylinder is being filled. The amount absorbed varies 
 with the kind and condition of the wood, being greatest in the 
 case of porous woods air-dry and least for resistant woods when 
 green, but generally ranges from about 5 to 20 percent. Some 
 treating plants allow for this "initial absorption," and deduct 
 10 percent from the total amount of preservative to be forced 
 into the wood after pressure is applied.^ There is no satisfactory 
 way of determining just what this initial absorption will be, and 
 it must be worked out through experience at each plant. The 
 
 1 Some treating engineers claim that blowing the preservative out of the 
 treating cylinder into the measuring tank also blows some of the preserva- 
 tive out of the wood, especially if it is porous. As shown above (see "final 
 air pressure"), this is quite likely to occur. 
 
OPERATION OF WOOD PRESERVING PLANTS 117 
 
 volume of sawed timbers can usually be determined with suffi- 
 cient accuracy by direct calculation. 
 
 Expansion of Creosote. — Creosote expands considerably when 
 heated, averaging about 1 percent for every 22 1/2° F. rise in 
 temperature. It is frequently run into the treating cylinder at 
 about 200° F. and its temperature invariably falls from 10° to 60° 
 when it strikes the timber. Unless brought back to its tempera- 
 ture at entrance this contraction may be charged against absorp- 
 tion. Similar errors will be introduced in taking the final reading 
 of absorption when the height of the oil in the measuring tank 
 after the treatment has been completed is subtracted from the 
 height before treatment, unless the temperature at both times is 
 the same. It is important, therefore, to keep the temperature of 
 the oil as nearly constant as possible (with no greater variation 
 than 20° F.) ; or, if this cannot be done, to correct for temperar 
 ture errors by using the proper coefficients of expansion. For 
 zinc treatments and others of a similar nature such corrections 
 need not be made. 
 
 Expansion of the Cylinder. — When hot creosote enters the 
 comparatively cool treating cylinder it produces an expansion of 
 the metal, which is further augmented by an internal pressure 
 often as high as 175 pounds per square inch. For ac ylinder made 
 of 3/4-inch boiler steel, 7 feet in diameter and 132 feet in 
 length, this increase in volume may amount to about 18 cubic 
 feet, equivalent to an absorption of about 1187 pounds of 
 preservative. 
 
 Compression of the Oil and Wood. — When pressure is ap- 
 plied to creosote the oil is compressed. At most, however, this 
 can produce only an insignificant error, since creosote under 
 ordinary operative conditions compresses less than one-tenth of 1 
 percent. The error due to the compressibility of the wood is also 
 insignificant. Some tests were made at the U. S. Forest Prod- 
 ucts Laboratory in which 20 pieces of green red oak and black 
 oak, 2 by 2 inches in cross section, were tested in a 100,000- 
 pound machine, the load being applied radially and tangentially. 
 The average modulus of elasticity was 50,375 pounds per square 
 inch. Disregarding the longitudinal dimension, the volumetric 
 compression due to an exterior pressure of 200 pounds per square 
 inch ranged from 0.51 to 1.30 percent, or an average of 0.80 per- 
 cent. This compression is probably much in excess of that which 
 takes place in practice, since when wood is submerged in a 
 
118 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 preservative fluid the pressure is applied from all directions. 
 Furthermore, at least a part of this pressure is transmitted to 
 the interior. It would seem, therefore, that the decrease in the 
 volume of wood undergoing treatment, due to the pressure 
 exerted on it, can be entirely disregarded. 
 
 "Kickback" of Preservative. — When pressure is applied to a 
 cylinder charge, the oil, wood, and air confined in the wood are 
 under compression and the cylinder is under tension. If the pres- 
 sure is released a certain amount of the preservative will be forced 
 out of the cylinder, although it remains constantly full. The 
 amount of preservative thus forced out will be called the "kick- 
 back." It varies with many conditions, and unless provided 
 for may result in errors of measurement for absorption of from 
 10 to 40 percent. In the treatment of air-seasoned red oak and 
 maple ties at the U. S. Forest Products Laboratory by the full- 
 cell process it was necessary, after the desired absorption had 
 been reached, to allow from 20 to 30 percent for the oil which did 
 not remain in the ties. 
 
 To secure data on the variability of the "kickback" a careful 
 series of tests was run on 36 pieces of air-dry longleaf pine. These 
 were cut 2 inches by 4 inches by 4 feet, matched, divided into 
 three groups of 12 each, and treated in three different runs in a 
 cylinder approximately 18 inches in diameter and 4 feet long. 
 In all cases the drip was stopped when it amounted to less than 
 1/2 pound of creosote in a half-hour period. The runs were 
 made as follows: 
 
 Run 1. — No preliminary or final vacuum was used. The 
 cylinder was filled with creosote in 6 minutes and the oil raised 
 to a temperature of 180° F. A pressure of 120 pounds per 
 square inch was immediately applied and held for 7 minutes. 
 The pressure was then released through the top of the cylinder 
 for 15 minutes, after which the cylinder was drained and the 
 wood permitted to drip for 121 minutes, when it was removed 
 and weighed. 
 
 Run 2. — After the wood was placed in the cylinder a prelimi- 
 nary vacuum of 25 1/2 inches was held for 15 minutes, the total 
 vacuum period amounting to 22 minutes. Without breaking 
 the vacuum the creosote was then drawn into the cylinder, the 
 operation consuming 5 minutes. The temperature of the creo- 
 sote on entering the cylinder dropped to 125° F. It was raised 
 to 181° F. in 12 minutes, tvhen a pressure of 120 pounds per 
 
OPERATION OF WOOD PRESERVING PLANTS 119 
 
 square inch was immediately applied and held for 3 minutes. 
 The pressure was then released for 16 minutes through the top 
 of the cylinder, after which the cylinder was drained and the 
 wood permitted to drip for 73 minutes, when the charge was 
 removed and weighed. 
 
 Run 3. — A preliminary air pressure of 50 pounds per square 
 inch was immediately applied and held for 15 minutes, after 
 which the oil was pumped into the cylinder against this pressure, 
 the operation taking about 10 minutes. The temperature of the 
 oil on entering the cylinder dropped to 156° F. It was then 
 raised to 180° F., consuming 9 minutes. During the heating 
 period the pressure in the cylinder varied between 55 and 70 
 pounds per square inch. As soon as the oil reached 180° F. a 
 pressure of 120 pounds per square inch was applied and held 
 for 78 minutes. The pressure was then released through the 
 top of the cylinder for 14 minutes, after which the cylinder was 
 drained and the wood permitted to drip for 128 minutes, when 
 the charge was removed and weighed. 
 
 The results of these runs are given in Table 7. It will be seen 
 that the "kickback" was least when a preliminary vacuum was 
 drawn, and greatest when the cylinder was first filled with com- 
 pressed air.^ Similar results were secured on full-sized ties, as 
 is shown in Figs. 12 and 13. 
 
 To illustrate the possible source of error through this "kick- 
 back" on the release of pressure, suppose, for example, it amounts 
 to 20 percent, and the specifications call for a 10-pound per cubic 
 foot injection in cross-ties of 3.5 cubic feet each. If the "kick- 
 back" is disregarded and the pumps kept running until the gauges 
 show an injection of 10 pounds per cubic foot and the pressure is 
 then released, only 8 pounds per cubic foot will be left in the ties. 
 If, on the other hand, the "kickback" is considered, then the 
 pumps will be kept running until the gauges indicate an absorp- 
 
 ' When the preliminary vacuum was drawn, only 3 minutes of oil pressure 
 were required to force 12 . 3 pounds of oil per cubic foot into the wood, but 
 when the cylinder and wood were first filled with compressed air it took 78 
 minutes to force 12 pounds of oil per cubic foot into the wood. That the 
 preliminary vacuum rendered it easier to force the preservative into the 
 wood is therefore apparent. After the run the sticks were split and the 
 penetration in run 3 was found to be slightly greater than in runs 1 and 2. 
 Furthermore, the sticks in run 3 were treated more uniformly than in the 
 other runs, especially run 2, in which the penetration and absorption were 
 very irregular. 
 
120 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 
 Final absorption 
 (oil remaining in 
 
 wood after "kick- 
 back" and drip) 
 
 per cubic foot 
 
 Pounds 
 7.2 
 
 9.4 V 
 6.5 
 
 o 
 
 g 
 
 >> 
 
 1 
 
 .-a 
 O 
 
 a 
 
 a" T-H CO 00 
 ■j^ (N t- IM 
 
 Amount 
 
 per cubic 
 
 foot 
 
 Pounds 
 0.9 
 0.5 
 1.0 
 
 M 
 
 m 
 
 % 
 
 "Kickback" or amount of pre- 
 servative forced out of cylinder 
 on release of pressure 
 
 1-2 
 
 Is 
 
 Percent 
 37.0 
 20.0 
 37.5 
 
 1 
 
 .a »o « ■* 
 g rt rt rt 
 
 1 
 
 O 
 
 o 
 o 
 
 Amount 
 
 per cubic 
 
 foot 
 
 Pounds 
 4.80 
 2.40 
 4.50 
 
 Maximum amount 
 
 of preservative 
 forced into wood at 
 
 end of pressure 
 period per cubic foot 
 
 Pounds 
 12.9 
 12.3 
 12.0 
 
 O 
 
 o 
 
 'I 
 
 a 
 
 o 
 M 
 
 'l. 
 
 s 
 
 Temperature of pre- 
 servative in treating 
 cylinder 
 
 180-185 
 180-181 
 180-184 
 
 O 
 0, 
 
 1 
 
 It 
 
 H 
 
 © pi 
 
 Pounds 
 120. 
 120 
 120-130 
 
 1 
 
 .a i> CO 00 
 
 
 a . 
 a o 
 
 a a 
 
 rH N CO 
 
 tion of 12.5 pounds per cubic foot, which 
 on the release of pressure will leave 10 
 pounds per cubic foot in the ties. If 
 this "kick-back" is released through an 
 underground tank or some measuring 
 tank other than the one used during 
 treatment (and this is a common prac- 
 tice), the chances for error in measur- 
 ing the absorption are increased. 
 
 Expansion of Wood. — Another pos- 
 sible source of error in measuring ab- 
 sorption is the expansion of the wood 
 due to raising its temperature. Assum- 
 ing the thermal coefficient of linear ex- 
 pansion of wood, 0.00001 per degree 
 Centigrade parallel to the fiber and 
 0.00006 across the fiber^ and that the 
 wood is raised in temperature 60° C. 
 (140° F.) during treatment, then the 
 increase of volume in a charge of say 800 
 ties will be about 22 cubic feet, equiva- 
 lent to about 1,386 pound of creosote, 
 or 1.7 pounds per tie. If the wood is 
 raised more than 60° C. in temperature, 
 the volume increase will, of course, be 
 greater. 
 
 Extent of Possible Errors. — The ex- 
 tent of the various errors possible in 
 measuring absorption may be illustrated 
 by the following example: Assume the 
 treating cylinder to be 7 feet in diameter, 
 132 feet long, and to hold a charge of 
 800 7-inch by 9-inch by 8-ft. ties; as- 
 sume also that 10 pounds of creosote 
 per cubic foot are to be injected into 
 and left in the ties; that a pressure of 
 175 lb. per square inch is used during the 
 treatment; that the oil in the measuring 
 tank is maintained at 200° F. and is in- 
 
 ' Experiments of Glatzel and Villari: Smith- 
 sonian physical tables, 5th rev. ed., p. 223. 
 
OPERATION OF WOOD PRESERVING PLANTS 121 
 
 jected into the wood at 180° F.; and that the normal tempera- 
 ture of the cylinder and wood is 60° F. With all gauges work- 
 ing perfectly, no leaks of any kind occurring, all air out of the 
 cylinder when the oil pump is started, and the volume of the 
 ties accurately known, the following errors may take place: 
 
 Founds 
 per tie 
 
 1. Chargeable to contraction in the volume of creosote 1 . 85 
 
 2. Chargeable to the expansion of the cylinder due to temperature 1 . 35 
 
 3. Chargeable to the "kickback" (assumed to be 20 percent of the 
 
 absorption) 7 . 00 
 
 Total positive errors 10 . 20 
 
 4. Chargeable to the expansion of the wood 1 . 50 
 
 Total in excess of apparent absorption 8.7 
 
 Thus, out of a total specified injection of 10 pounds per cubic 
 foot, or 35 pounds per tie, 8.7 pounds per tie may be forced 
 into the cylinder, but either will not go into or not remain in the 
 ties, constituting a total error of about 25 percent. In plants 
 operating with zinc chloride, item 1 may be eliminated and item 
 3 will be less than that given. 
 
 Purity of the Preservative. — The composition of the preserva- 
 tive is subject to change so that check analyses of it should be 
 made from time to time to see that it meets specifications. 
 
 With creosote, the chief difficulty likely to occur is with the 
 water content of the oil. Leaky steam coils, or snow or ice on 
 the wood, or water in the wood are all liable to adulterate the 
 oil with water. It is not necessary to remove all of the water 
 but large amounts (over 5 percent) are objectionable and it is 
 not good practice to allow for this by giving the timber a heavier 
 injection. Proper procedure is to remove the water. This may 
 be done in some cases by allowing the oil to stand for several days 
 in a tank,i when the water may be drawn from the top of the oil, 
 or by boiling off the water in tanks equipped with steam coils. 
 In either case loss of some oil is almost sure to occur. 
 
 It sometimes happens that the carbon content of the creosote 
 will increase as it is used over and over again, so that timber 
 treated with "old" oil will look much blacker than timber treated 
 with "fresh" oil. The author has known of inspectors refusing 
 
 * Some engineers alternately heat and cool the oil several times before 
 drawing off the water. 
 
122 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 to accept treated timber because it did not look "black." Free 
 carbon will not penetrate wood, has no preservative value, and 
 detracts from the quality of the oil. About the only practical 
 way to guard against too large a percentage of free carbon is to 
 be careful in the purchase of the oil. 
 
 It is also asserted, at times, that the composition of creosote 
 changes because that portion of it which enters the wood and is 
 then redrawn carries with it some of the soluble constituents in 
 the wood. While there is a possibility of its doing this, careful 
 tests have failed thus far to show any marked changes in the oil 
 due to this cause. 
 
 Solutions of zinc chloride also need careful attention. Common 
 practice is to place a hydrometer in the solution and if it shows 
 correct gravity to assume the strength to be correct. This prac- 
 tice is subject to error because foreign substances such as other 
 inorganic salts or materials dissolved from the wood may change 
 the gravity. Some careful tests made at the U. S. Forest Prod- 
 ucts Laboratory have also shown that the strength of a zinc- 
 chloride solution may be changed by successive treatments, the 
 solution tending to weaken. 
 
 Pollution of Streams. — Complaint has been made against some 
 treating plants because they polluted streams with waste oil. 
 This comes largely from the cylinders and steam exhausts. Of 
 course, no plant is going to deliberately waste preservative and 
 it is believed that such complaints can be entirely avoided as they 
 are indications of bad management. The use of a final vacuum 
 in drying the timber, and attention to steam coils to see that they 
 do not leak, will remedy much of the difficulty. All drains can 
 be carried to a common settling tank, where by a system of over- 
 flow chambers arranged in the tank practically no oil will escape. 
 
 Inspection of Treatments. — Controversies between purchasers 
 of treated timber and operators of treating plants over the in- 
 spection of treatments have been no more common than in other 
 industries which are of comparatively new growth and where so 
 many factors are involved, but much needless dispute has oc- 
 curred because one party or the other has not been sufficiently 
 trained to recognize legitimate demands. Attempts to cover up 
 fraudulent work have, of course, been made and probably will be 
 as long as the industry exists, but such cases are decidedly in the 
 minority, for corrupt practice sooner or later becomes generally 
 recognized and eventually kills itself. 
 
OPERATION OF WOOD PRESERVING PLANTS 123 
 
 Much of the trouble can be laid entirely on the purchaser, who 
 frequently insists upon impractical specifications and unattainable 
 results. It is the author's opinion that considerable freedom 
 should be given the operator as regards the details of the treat- 
 ment, and that only a few essential features need be required. 
 We will attempt to give here only those which are more important 
 and applicable to general conditions. 
 
 First, perhaps, comes the wood itself. It should be remem- 
 bered that wood is a product grown under a wide variety of con- 
 ditions and hence varies greatly in its structure. It is practically 
 impossible to get two pieces which are alike, and therefore speci- 
 fications for wood should not be too stringent. It is reasonable to 
 expect, however, that only sound wood be furnished. In this 
 connection, wood which is sap-stained should not be confused 
 with wood which is decayed. In specifying rings per inch, knots, 
 crooks, tapers, etc., care should be exercised so that the speci- 
 fications are reasonable and do not require the rejection of large 
 quantities of good material. As regards the kinds of wood, the 
 specifications should recognize that the same kind may go under a 
 variety of names; hence no chance formisunderstandingshould be 
 left. 
 
 The composition of the preservative to be used should be clearly 
 stated and also its riiethod of analysis, and the inspector should be 
 granted permission to take samples for analysis as often and from 
 whatever source he pleases. Requirements in this regard can be 
 made fairly rigid. 
 
 The treating operator can also be held to have his plant in 
 fit condition for accurate work, and if considered necessary the 
 inspector can measure all essential pieces of apparatus in order 
 to make sure the dimensions furnished are correct. Errors 
 in operation already described should be recognized, so that they 
 can be taken into account in making determinations of absorption. 
 As for the treatment proper, the essentials to specify are the maxi- 
 mum temperatures to be used and the absorption of preservative 
 required. This should be final absorption, or the amount of pre- 
 servative actually in the wood at the time it is removed from the 
 cylinder, free from drip. Because wood varies so, it should not 
 be expected that all pieces are to have the same absorption. They 
 may vary widely. In all cases, as deep and uniform a penetra- 
 tion as possible should be required, and the inspector should 
 
124 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 know what is possible before he attempts to pass judgment on the 
 results. A complete penetration of all sapwood should always be 
 secured and the specifications should be so framed as to admit 
 of this. Woods which vary widely in their resistance to injection 
 should not be treated in the same charge; neither should the 
 mixing of green and seasoned wood in the same run be allowed. 
 In all cases the difference in the height of the preservative in the 
 measuring tank before and after the treatment has been made 
 should furnish the final basis for determining the absorption 
 secured; or if seasoned wood is treated, the weights on the track 
 scales should be used. Sources of error due to friction of gauges, 
 differences in temperatures, etc., should be carefully considered 
 in determining final absorption. 
 
 The Cost of Pressure Plants. — The cost of pressure plants is 
 exceedingly variable even for plants of the same capacity. Any 
 estimate, therefore, must be considered with a wide latitude.. 
 The variations in cost are due largely to the type of buildings, 
 the number of processes practised, the yard layout, and local 
 soil and surface conditions. The author knows, for example, 
 of two plants with cylinders approximately 6 feet 2 inches in 
 diameter by 132 feet in length, equipped to treat timber by 
 the same methods, one of which cost $65,000 and the other 
 $170,000 complete. 
 
 With these variations in mind, the following estimate of a 
 2-cylinder plant with cylinders 7 feet in diameter by 132 feet 
 in length, equipped to treat by any standard process and of 
 first class construction, is given: 
 
 Track and grading S35,000 
 
 Retorts with all piping installed 13,000 
 
 Three 150 H.P. boilers complete 4,000 
 
 Sewers 1,500 
 
 Buildings 30,000 
 
 Pumps (compressor, vacuum, hydraulic, service) 5,000 
 
 Piping, valves, complete 7,000 
 
 Fire hydrants and equipment 3,500 
 
 Electric plant complete 4,000 
 
 Miscellaneous plant items 4,000 
 
 One 12-ton locomotive crane 4,200 
 
 One dummy engine 3,000 
 
 Cylinder cars (190) 8,500 
 
 Total S122,700 
 
OPERATION OF WOOD PRESERVING PLANTS 
 
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126 the' PRESERVATION OF STRUCTURAL TIMBER 
 
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OPERATION OF WOOD PRESERVING PLANTS 127 
 
 Through the courtesy of the Allis-Chalmers Company, the 
 author is able to give Table 8, which contains estimates of the 
 cost of wood preserving plants of various capacities. The plants 
 given in the table are arranged for either the Burnett, Wellhouse, 
 Bethel, Rueping, Lowry, or Card process. In using this table, 
 variations of at least 20 percent either way can be expected. 
 
CHAPTER VIII 
 
 PROLONGING THE LIFE OF CROSS-TIES FROM DECAY 
 AND ABRASION 
 
 Selection of Species. — At the present time, practically any- 
 kind of tree which is large enough to make a cross-tie is used for 
 this purpose. The result is a great variety of ties differing 
 widely in their properties. It stands to reason, therefore, that 
 the service obtained from ties must be very erratic. The diffi- 
 culty now generally experienced by many American railroads to 
 secure adequate supplies of good ties makes it impossible to be 
 too stringent in specifying the kinds of wood which will be used. 
 If planting trees for ties becomes general, the question of proper 
 selection of species will be a very important one, but at the pres- 
 ent time this feature is recognized only in the price paid for ties 
 and no special selection is made. 
 
 Common practice now consists in dividing the various kinds of 
 ties into two groups, viz., ties to be used without preservative 
 treatment and ties to be treated. The former group includes 
 those woods which are naturally durable, the latter those which 
 if placed in a track untreated would decay in a few years. 
 
 The ideal tie for use without treatment is one which is not only 
 very resistant to decay but which is hard and will hold spikes 
 and resist rail cutting without serious splitting or checking. Of 
 our more common American woods, black locust and white oak 
 best meet these requirements. Redwood, cedar, and cypress 
 are very durable but are inferior to black locust and white oak as 
 regards strength. 
 
 If the tie is to be treated, the prime qualities are strength, 
 hardness, and permeability. Red oak, maple, birch, beech, and 
 elm best fulfill these conditions. A large variety of other woods 
 are, of course, also used, chief among which are the pines, firs, 
 spruces, gums, hemlocks, chestnut, and tamarack. Irrespective 
 of marketing conditions, the value of these woods for tie purposes 
 depends directly upon their ability to meet the requirements 
 just mentioned. In other words, a wood which is hard and por- 
 
 128 
 
PROLONGING THE LIFE OF CROSS-TIES 129 
 
 ous is more valuable for a "treatment tie" than a wood which 
 is soft and resistant to impregnation, and should therefore com- 
 mand a higher price. Maple, for example, is worth more for a 
 cross-tie than white pine or spruce because, when treated, it will 
 give better service. 
 
 Unfortunately, conditions are still such in our country that 
 many trees are cut for ties which ought to be cut for more valu- 
 able products such as veneer or lumber. Black walnut, cherry, 
 and hickory are conspicuous examples. Where these trees occur 
 scattered in forests or woodlots, it is often easiest to market them 
 in the form of ties, but whenever possible, they should not be 
 used for this purpose, as it results in a distinct economic loss of 
 valuable material. 
 
 Hewed Versus Sawed Ties. — Approximately 75 percent of all 
 ties purchased are hewed. In the tie industry as a whole the 
 methods of manufacture are undergoing no general or perma- 
 nent changes. The probable reasons are that the railroads 
 obtain, either directly or indirectly through tie companies, a 
 large proportion of their ties from farmers and small holders of 
 timber who cannot afford to saw them, and also because the im- 
 portance of utilizing timber to the best advantage has not yet 
 been keenly felt. Under certain conditions the sawing of ties 
 may be impracticable, as when, for example, only a few trees 
 suitable for cross-ties are available, or when ties are cut from tops 
 of felled trees. In such cases it is much better to utilize the wood 
 by hewing it into ties than to leave it in the forest. The claim 
 is often made that hewed ties are more durable than sawed ties 
 because they shed water better. Nothing is known by the U. S. 
 Forest Service to substantiate this impression. Even if untreated 
 hewed ties should be more durable than sawed ones, this advan- 
 tage disappears when the ties are treated. On the other hand 
 there are many serious objections to the use of hewed ties, and 
 these will increase in importance in direct proportion to the num- 
 ber of ties treated with preservative. Chief among these objec- 
 tions are (1) unequal bearing afforded tie plates and rails, (2), 
 lack of uniform volume, and (3) unnecessary waste of valuable 
 material. 
 
 Bearing Afforded Tie Plates and Rails. — The heavy tonnage 
 on American railroads necessitates the use of some form of tie 
 plate on practically all first-class construction. Hewed ties 
 seldom offer a uniform bearing surface to the plate or rail, and 
 
130 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 unless specially adzed before placement soon wear unevenly and 
 must be removed. An inspection of test ties on the Chicago 
 & Northwestern track showed in many cases that one edge of the 
 plate had cut into the tie to a depth of over 1/2 inch, while 
 the other edge was not even flush with the surface. With sawed 
 ties the bearing over the surface is more uniform and rail cutting 
 is considerably reduced. The introduction of tie-boring and 
 adzing machines is doing much to improve the bearing of plates 
 on the ties and should cut down mechanical wear appreciably. 
 
 Uniformity in Volume. — Since tie inspectors offer no objec- 
 tion to, but rather favor, ties of greater dimensions than those 
 specified, the tie manufacturer rarely hews a large log to the 
 standard size. Thus the cubic content of hewed ties may vary 
 from that of the uniform dimensions allowed to about twice the 
 size specified. Practically all contracts for treating ties state 
 that so much preservative shall be injected per cubic foot of 
 wood. With hewed ties no treating plant knows accurately 
 what this volume is until after the ties have been treated. To 
 obtain the total quantity of preservative to be used, it is custom- 
 ary to figure that a tie will contain a certain amount of wood, 
 and to multiply this figure by the number of ties and the amount 
 of preservative to be injected per cubic foot. For example, to 
 figure the amount of creosote needed to treat 1000 cross-ties 
 6 inches by 8 inches by 8 feet with 10 pounds of oil per cubic foot, 
 the calculation would be 1000 X 2.67 X 10 = 26,700 pounds. If 
 the hewed ties average 3.2 cubic feet, though figured as of 
 standard size, the total amount of preservative would be the 
 same, viz., 26,700 pounds, but the amount per cubic foot would be 
 only 8.3 pounds instead of 10, as specified. Sawed ties are cut to 
 more exact dimensions, and errors of this kind are improbable. 
 
 Waste of Material. — To hew a tie necessarily entails an enor- 
 mous waste of material. Based on actual field data the waste 
 by hewing varies from 25 to 75 percent' (Fig. 17). Logs 15 
 inches in diameter furnish, as a rule, only one hewed tie, but if 
 sawed they furnish two. Whenever possible the tie hewer selects 
 trees of about 12 or 14 inches in diameter. The waste of wood 
 each year in the United States from hewing ties amounts to about 
 285,000,000 cubic feet, a quantity equivalent to about 80 percent 
 of the total amount of pulpwood used in the United States in 
 
 1 U. S. Forest Service Bulletin 64, "Loblolly Pine in Eastern Texas, with 
 Special Reference to the Production of Cross-ties," by Raphael Zon. 
 
PROLONGING THE LIFE OF CROSS-TIES 
 
 131 
 
 1909. This is an absolute waste, as it is not even used for fuel. 
 (See Plate XIII, Fig. A.) 
 
 Form of Cross-ties. — Practically all of the wooden cross-ties 
 now used on. steam railroads in the United States are rectangular 
 in cross section. Their size is by no means uniform, varying in 
 width from 6 to 10 inches, in depth from 6 to 7 inches, and in 
 length from 8 to 9 feet. These ties are sometimes cut either with 
 a saw or axe on all four sides (see Plate XIII, Fig. B), in which 
 case they are said to be "squared." In many cases only the top 
 and bottom are cut, leaving the sides the natural shape of the tree. 
 When thus made from small trees the ties are called "pole ties." 
 In Europe a large number of ties are cut larger on the base than 
 on the top and are commonly referred to as "half-round ties." 
 
 ■BiaSaw-keTl^I^EinEs 
 
 Fig. 17. — Ideal economy in manufacturing a cross tie. A = tie 6 X 8 
 inches; B = board 7 inches wide; C. C. = boards 5 1/2 inches wide; D = 
 board 9 1/2 inches wide; E = board 7 1/2 inches wide; F = board 3 inches 
 wide. (Diagram courtesy of the Forest Service.) 
 
 Such ties are also used to a limited extent in our country. (See 
 Plate XIII, Fig. C.) One railroad uses a form of tie which will 
 economize in timber by cutting them triangular. (See Plate 
 XIII, Fig. D.) It is believed that the form of cross-ties, especially 
 as regards the distribution of the sapwood on them, is very im- 
 portant and an item too frequently overlooked in track con- 
 struction. It is just as logical to specify how ties to be treated 
 shall be sawed or hewed as regards their sapwood 'content and 
 its distribution, as it is to specify a difference in price due to 
 a difference in the kind of wood. Exceptions of course occur, 
 as, for example, in those ties whose heartwood treats as easily 
 
132 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 as the sapwood. Sapwood is easy to impregnate with pre- 
 servatives, while the heartwood is generally very resistant. 
 This difference in the resistance to treatment between the sap 
 and heartwood of the same tie is often very much greater than 
 the difference in treatment between two ties of widely different 
 varieties of wood. In certain species like the red oak, hemlock, 
 and the ash, this condition is not true, but in the majority of cases 
 it is. With most ties composed of part heart and part sapwood, 
 when placed in a cylinder and injected with a preservative, most, 
 if not practically all of the preservative will go into the sapwood. 
 
 D E 
 
 G 
 
 H 
 
 □ □ 
 
 Fig. 18. — Showing the character of the preservative treatment in ties prop- 
 erly and improperly manufactured. 
 
 To secure best results it is of considerable importance, therefore, 
 to specify how this sapwood should be distributed. The best 
 kind of cross-tie intended for treatment is one which has a uniform 
 distribution of sapwood on all surfaces (Fig. 18 C). A^ tie of 
 this kind, can be very efficiently protected against decay. Un- 
 fortunately, only a comparatively small number of ties are of 
 ^this kind, and even those that are, are usually of low crushing 
 strength. By far the largest percentage of ties now used are 
 composed mostly of heartwood or needless sapwood, as shown in 
 Fig. 18 A and Fig. 18 B . When ties of this kind are treated accord- 
 ing to the ordinary run of specifications, practically all of the 
 
Plate XIII 
 
 Fig. a. — Method of hewing oak ties in Tennessee. 
 
 Service photo.) 
 
 Note waste. (Forest 
 
 Fig, 
 
 -Rectangular cross-ties — standard form in the United States. 
 
 (Facing page 132.) 
 
Plate XIII 
 
 Fig. C. — Standard Prussian ties of Baltic pine. (Forest Service photo.) 
 
 Fig. D.— Triangular cross-ties— Great Northern Ry. (Forest Service 
 
 photo.) 
 
PROLONGING THE LIFE OF CROSS-TIES 133 
 
 preservative will go into the sapwood, leaving the heart faces with 
 only a superficial penetration. The greatest wear on a tie comes 
 on its face immediately under the rail or plate. This is the por- 
 tion which should have the greatest and not the least protection 
 against decay, as now generally occurs due to the present methods 
 of manufacture. If ties of the type shown in Fig. 18 A and Fig. 
 18 B are treated, they can unquestionably be made to absorb the 
 amount of preservative specified— say 10 pounds per cubic foot — ■ 
 but most of the preservative will be in those portions of the tie 
 where it will do the least good. If, now, these ties were sawed 
 as indicated by the dotted lines in the sketch, it would be possible 
 to secure just as long a life from them with a much less consump- 
 tion of preservative. 
 
 For example, consider a modern treating plant having an 
 output of approximately 800,000 ties per year : If the ties are im- 
 pregnated with 10 pounds of creosote per cubic foot, the oil cost- 
 ing 6 cents per gallon and the ties containing approximately 3 
 cubic feet, the total amount of the oil used would be approxi- 
 mately 24,000,000 pounds. If, now, the ties had been cut as indi- 
 cated in the sketch, it would be possible with a consumption of 
 about 6 pounds of creosote per cubic foot to protect them as 
 effectively as with 10 pounds in the former case. This would 
 result in a net saving of approximately 4 pounds per cubic foot 
 or 12 pounds per tie, equivalent to about 9 cents per tie for cost 
 of preservative, or $72,000 in one year's operation. 
 
 There are other ways in which this point could be argued. 
 For example, if this unnecessary sapwood were removed, could 
 not the life of the tie be increased over what it would have been, 
 provided the quantity of oil injected in both cases remained the 
 same? A company would be justified in paying more for prop- 
 erly sawed ties intended for treatment than for ties which are 
 improperly sawed or hewed, especially when the treatment is one 
 using straight coal-tar creosote. It is the author's opinion that 
 roads using this method of treatment could very well afford to 
 insert another clause in their specifications for cross-ties, concern- 
 ing the amount and distribution of sapwood, and even go to the 
 extent of paying a higher price for ties in which the sapwood was 
 properly distributed. They would thereby save an appreciable 
 item in the cost of treatment. The roads which do not use 
 treated ties or which adhere to a zinc treatment would not be 
 benefited to the same degree by a requirement of this kind. 
 
134 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 Such procedure would simply be a step in advancing the increased 
 efficiency with which cross-ties can be utilized, with a view to 
 decreased cost in track maintenance and operation. The diffi- 
 culties in putting it into practical use would, in some cases, be 
 unsurmountable, but where conditions of production are such 
 that a requirement of this kind could be employed, it is believed 
 its adoption would unquestionably result in decided profit. 
 
 In Fig. 18, A, B, and C. represent the cross sections of three 
 ties, the shaded portion being sapwood and the white, heart- 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 155 
 
 
 
 
 
 
 
 
 
 
 
 
 The Effect of Form o£ Pile 
 upon 
 Bate of Seasoning 
 Solid Pile 9 1 9 
 Opea Pile 7x2 
 
 
 
 
 
 
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 JuQC July August Septembex 
 
 Time- Weeks 
 
 Fig. 19. — Effect of the form of piling upon the rate of seasoning of lodge- 
 pole-pine ties. 
 
 wood. The dotted lines show how these ties could be improved 
 by slabbing the sides. 
 
 If impregnated with creosote, the ties would appear as in Figs. 
 18 D, E, and F. Note the heavy impregnation on the sides and 
 the very slight impregnation on the faces in Figs. 18 D and E. 
 Figs. 18 G and H show ties A and B slabbed on the sides and then 
 impregnated with creosote. Note the even distribution of the 
 preservative and the heavier injection on the faces than in D and 
 E, thereby giving greater protection to the tie where it is most 
 needed and at the same time consuming less of the preservative. 
 
 Stacking Ties for Seasoning. — Different kinds of wood and 
 climate require different methods of piling. The closer the ties 
 
PROLONGING THE LIFE OF CROSS-TIES 135 
 
 are piled the slower will be their loss in. weight. In no case should 
 more than two ties in a pile come in contact with the ground. 
 The most open form is the triangular one, which can be rapidly 
 made and is well adapted for use along the right of way. It 
 should not, however, be used for many hardwoods cut in summer, 
 since these will check badly. Good forms of piles are the 7 by 2, 
 7 by 1, and 8 by 1. (See Plate XIV, Fig. A.) These are well 
 adapted for softwoods and for most hardwoods cut in summer. 
 They are easy to build and permit of free circulation of air. 
 When it is desired somewhat to retard the rate of drying, the 8 
 by 2 or the 10 by 1 form should be used, or if these are still too 
 open, the 7 by 7 form. An advantage of the 7 by 1, 8 by 1, 10 
 by 1, and similar forms is that no tie lies flat on another, thus 
 giving an easy run-off for rain water and a free circulation of 
 air. In practically no case should untreated ties be piled solidly 
 9 by 9, since such forms are exceedingly inefficient in regard 
 to seasoning and invite decay. The effect of the form of piling 
 upon the rate of seasoning is shown in Fig. 19. 
 
 Though the U. S. Forest Service has made many tests to de- 
 termine the effect of different forms of roofs on the seasoning of 
 ties, the data secured are not conclusive. However, a slanting 
 roof of ties is fairly efficient in shedding water, and when not re- 
 quiring too much additional labor can be employed advantage- 
 ously. 
 
 Ties cut from conifers are less likely to check during seasoning 
 than ties cut from broadleaf trees, and in consequence can be 
 piled more openly^ 
 
 If ties are seasoning too fast they should be piled closer to- 
 gether (see Plate XIV, Fig. B) ; if seasoning too slowly they should 
 be piled more openly. Ties cut in winter can be piled more 
 openly without danger of checking than' ties cut in summer. 
 
 The length of time ties should season before treatment will 
 vary primarily with the species of wood, form of pile, and period 
 of the year. In general, ties cut in spring and summer will be 
 seasoned sufficiently for treatment by the end of the following 
 autumn; ties cut in early spring will be seasoned sufficiently by 
 the following early autumn; the seasoning period varying from 
 about 2 to 4 months. Ties cut in autumn and winter will be 
 sufficiently seasoned by the end of the following spring, the period 
 varying from about 5 to 8 months. The periods necessary 
 
136 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 to season dense ties like the oaks will generally be from 2 to 
 3 months longer than those just given. 
 
 Figs. 20 and 21 illustrate these conditions; Fig. 20 representing 
 red gum ties which season very rapidly and Fig. 21 red oak ties 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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 Time-Months 
 
 185 
 
 
 
 
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 Mar. Apr. Ma; Jun. Jul. Aug. Sept. Oct. Nov. Dec. Jan. Feb. Mar. Apr. Maj Jun. JuU Aug. 
 Time-Montha 
 
 Fig. 21. — Rate of seasoning of red oak ties. 
 
 which season slowly. Both figures show the accelerated drying 
 in the warmer months and the retarding action of winter. 
 
 Grouping Ties to Secure Uniform Treatment. — The importance 
 of properly grouping ties before placing them in the treating 
 
PROLONGING THE LIFE OF CROSS-TIES 137 
 
 cylinder cannot be overemphasized. If ties offering unequal 
 resistance to penetration are treated at the same time, those 
 offering the greatest resistance will take practically no pre- 
 servative, while the others will get it all. Consequently, if ties 
 so treated are placed in a roadbed, the ones heavily injected will 
 outlast the others and the wear on the track will not be uniform. 
 Furthermore, when the ties inadequately treated decay, the load 
 which should be borne by them will be transferred to the sound 
 ones, hastening their mechanical destruction. Thus much of the 
 preservative will be wasted, since there is no economy in pre- 
 serving ties from decay after they have been worn out. The 
 aim, therefore, should be to have the ties depreciate uniformly, 
 and this can largely be brought about by grouping them in such 
 a manner that they will receive equal amounts of the preservative 
 uniformly diffused. Many tie plants already realize the import- 
 ance of grouping, and consider the added expense more than justi- 
 fied by the results secured. 
 
 The chief factors which determine the ease with which ties 
 may be impregnated are (1) the species of wood, (2) percent of 
 sap and heartwood, (3) moisture content. The less important 
 are conditions under which seasoned, time of cutting, and con- 
 ditions of growth. 
 
 Species of Wood. — It has been explained in Chapter III that 
 the species of wood differ greatly in their physical properties and 
 that this difference accounts in a large measure for the variable 
 results secured in preservative treatments. 
 
 Interesting experiments on 20,000 ties to ascertain the absorp- 
 tive properties were made by Mr. F. J. Angier in 1908-09 at the 
 treating plant of the Chicago, Burlington & Quincy Railroad, 
 using the zinc-creosote process. The results are summarized 
 in Table 9. 
 
 Class A includes ties absorbing less than 22 percent of their 
 volume; Class B, ties absorbing between 23 and 30 percent; 
 Class C, ties absorbing more than 30 percent. In all cases the 
 ties were kept in the cylinder until no more preservative could be 
 forced into them. With hardwoods, such as oak, hickory, ash, 
 beech, etc., the pressure was 175 pounds, but with softwoods 
 this was reduced to from 125 to 150 pounds per square inch. In 
 both cases the pressure was held for from 2 to 5 hours. No sepa- 
 ration of the ties was made on the basis of their proportion of sap- 
 wood and heartwood, but about 75 percent of them were hewed. 
 
138 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 Table 9. — Absobption op Peesebvative by Vaetoits Species op 
 Ceoss-ties^ 
 
 Class A 
 
 Kind of wood 
 
 Number 
 
 ties used 
 
 in the tests 
 
 Absorption 
 
 percent 
 
 of volume 
 
 Number 
 
 months 
 
 seasoned 
 
 in yard 
 
 Beech 
 
 Oak, red 
 
 Hemlock 
 
 Oak, pin 
 
 Hickory 
 
 Tamarack 
 
 Oak, white 
 
 Class B 
 
 Hard maple 
 
 Popular 
 
 Sycamore 
 
 Ash 
 
 Sweet gum 
 
 Chestnut 
 
 Class C 
 
 Shortleaf pine 
 
 White elm 
 
 Cypress, white 
 
 Red elm 
 
 Soft maple 
 
 Red birch 
 
 Tupelo gum 
 
 2,481 
 
 3,112 
 
 1,364 
 
 671 
 
 414 
 
 2,329 
 
 731 
 
 21.8 
 20.9 
 20.7 
 19.5 
 18.8 
 17.1 
 14.2 
 
 15 
 6-15 
 8-15 
 
 10 
 
 2- 8 
 
 6- 8 
 
 7 
 
 691 
 1,348 
 364 
 318 
 928 
 345 
 
 28.3 
 26.8 
 26.6 
 23.0 
 23.0 
 22.6 
 
 15 
 
 7- 9 
 
 7 
 
 2- 6 
 
 5- 9 
 
 12 
 
 2,192 
 872 
 662 
 626 
 599 
 775 
 790 
 
 36.9 
 36.6 
 35.4 
 34.9 
 33.1 
 33.0 
 30.7 
 
 5- 9 
 7-15 
 7- 8 
 
 6- 9 
 6 
 
 6- 9 
 
 Proportion of Sapwood. — As has been stated, the sapwood of 
 practically all woods native to the United States readily absorbs 
 preservatives. The heartwood, however, is much more resistant, 
 so much so in some cases that no effective treatment is possible. 
 Two hundred maple ties thoroughly air seasoned (the moisture 
 content ranging from 24 to 39 percent) were treated by the full- 
 cell and Burnett processes at the U. S. Forest Products Labora- 
 tory. It was found that of the ties given a full-cell treatment, 
 those containing 43.7 percent sapwood absorbed 10.48 pounds of 
 creosote per cubic foot, while those containing 82.7 percent of 
 sapwood absorbed 17.40 pounds per cubic foot. In the Burnett 
 treatments the difference was not so pronounced. Ties contain- 
 ing 46.2 percent sapwood absorbed 19.7 pounds of solution. 
 
 'Proceedings of Wood Preserver's Assn., 1911 
 
PROLONGING THE LIFE OF CROSS-TIES 
 
 139 
 
 while those which contained 80.5 percent absorbed 22.5 pounds. 
 Because of this difference in the absorption by sap wood and 
 heartwood, ties which contain large amounts of sapwood should 
 be treated separately. Differences in absorption by ties of the 
 same species, but with varying proportions of sapwood, are 
 often greater than in the case of widely different species. If the 
 ties are "pole" ties, it will be found that those of certain species 
 almost invariably fall in the same class when graded with refer- 
 ence to the percent of sapwood. The grouping will be approx- 
 imately as shown in Table 10. 
 
 Table IO.^Classification of Pole Ties Based on Their Sapwood 
 
 Content 
 
 Group I 
 Sapwood 1 inch or less in 
 width (leas than 20 per 
 cent of volume of tie) 
 
 Group 11 
 Sapwood 1 inch to 2| inches 
 in width (more than 20 per- 
 cent, but leas than 50 pei^ 
 cent of volume of tie) 
 
 Group III 
 
 Sapwood over 3 inches wide 
 
 (more than 50 percent of 
 
 volume of tie) 
 
 Oaks. 
 
 Douglas fir. 
 
 Cedar. 
 
 Chestnut. 
 
 Tamarack. 
 
 Hemlock. 
 
 Spruce. 
 
 Longleaf pine. 
 White pine. 
 Hard maple. 
 White elm. 
 Red elm. 
 
 Shortleaf pine. 
 
 Loblolly pine. 
 
 Western yellow pine. 
 
 Cypress. 
 
 Lodgepole pine. 
 
 Tupelo gum. 
 
 Red gum. 
 
 Sycamore 
 
 Poplar. 
 
 Soft maple. 
 
 Red birch. 
 
 Hickory. 
 
 Ash. 
 
 Beech. 
 
 This grouping does not, however, in all cases accurately rep- 
 resent the relative resistance to penetration of the various 
 species. For example, red oak, because of its porous nature, 
 can readily be penetrated to the center, and thus, in spite of its 
 comparatively small amount of sapwood, would be grouped with 
 ties of a structure resembling the elms. Also, the sapwood of 
 soft maple, hickory, ash, and beech is more resistant to treatment 
 than that of the other species mentioned in Group III. 
 
 If ties are cut from logs larger than 12 to 14 inches in diameter, 
 as is usually the case with sawed ties, the percentage of sapwood 
 may range from zero to the maximum shown in the table; hence 
 the grouping of such ties may be different from that given. For 
 
140 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 example, shortleaf pine ties cut with little or no sapwood would fall 
 in Group II, hard maple without sapwood in Group I. Sapwood 
 can be distinguished from heartwood by its difference in color, and 
 it is as a rule easy to separate ties into groups according to their 
 sapwood content. Such a separation will undoubtedly assist 
 in a pioper grouping of ties for treatment, but before this group- 
 ing can definitely be decided upon as the best, considerably more 
 experimenting will be necessary. 
 
 Moisture Content. — When ties are green the cell walls and 
 many of che cell spaces are filled with water. To properly inject 
 a preservative, at least a part of this water must be removed, and 
 the extent to which it has been removed governs the amount of 
 preservative which can be injected. It is important, therefore, 
 that all of the ties to be treated at one time should have approxi- 
 mately the same moisture content. One of the most practical 
 ways of insuring this is to pile the ties in the yard and thoroughly 
 air-season them. 
 
 The conditions under which ties season effect the uniformity 
 of the treatment. Ties seasoned too rapidly are likely to "case- 
 harden," which makes them more difficult to impregnate and 
 affects their strength. Moreover, whether ties are seasoned with 
 the bark on or off affects the treatment. It is good practice to 
 season all ties to be treated in one charge under the same condi- 
 tions. 
 
 Cutting Season. — The time of year the ties are cut also affects 
 the uniformity and degree of treatment. Several tramloads of 
 hemlock ties cut in the summer, fall, and winter were first air- 
 seasoned and then treated with zinc chloride, with the results 
 shown in Table 11. 
 
 Table 11. — Effect of the Season of Cutting on the Ab- 
 sorption OP Preservative 
 
 
 Weight per cubic foot 
 before treatment 
 
 Average absorption of 
 solution per cubic foot 
 
 Summer 
 
 Pounds 
 33.4 
 
 Pounds 
 12 9 
 
 Fall .... 
 
 36.2 10.0 
 
 37.3 8 9 
 
 Winter 
 
 
 
 
 It is probably safe to say that, aside from moisture content and 
 case-hardening, the effect of the time of cutting on the penetra- 
 tion and absorption of preservative can be neglected in commercial 
 
PROLONGING THE LIFE OF CROSS-TIES 141 
 
 work. Good practice consists in cutting all ties in winter or late 
 fall whenever possible. 
 
 Conditions of Growth. — The arrangement of the cells in the 
 same species of wood grown under different conditions may differ 
 to such an extent as to cause variability in the results of the treat- 
 ment. When that is the case, the ties should be grouped sepa- 
 rately. For example, a plant receiving red oak ties from the 
 South may find it advantageous to group them separately from 
 those received from the North. Moreover, ties cut from various 
 parts of the tree treat differently. 
 
 Although the above considerations sound very complicated, 
 they are not difficult of practical execution. It goes without say- 
 ing that the careful grouping of ties for treatment costs more 
 than not grouping them, but there is no doubt but what it will 
 far more than pay in the long run. This is particularly true for 
 treatments with creosote where the amount of preservative 
 forced into the ties is not the maximum amount they will absorb 
 but the amount called for by the specification. Grouping is 
 least essential when the ties are impregnated with a solution of 
 zinc chloride, which can be forced into them until there is no 
 more absorbed or until the point of refusal is reached. 
 
 Protection from Abrasion. — It has been estimated that from 
 10 to 75 percent of unprotected ties fail by rail and spike cutting;^ 
 the former figure referring to hard, quick-decaying ties like maple, 
 the latter to durable, soft ties like cedar. Since the number of 
 treated ties is increasing annually, this percentage will also in- 
 crease rapidly unless improved methods of fastening rails are 
 generally adopted. Already the amount of preservative injected 
 into ties is in some cases reduced because it is claimed to be more 
 than is necessary to prevent decay throughout their mechanical 
 life. With increased mechanical life of the tie the efficiency of 
 the preservative treatment may also be increased. 
 
 The most practical means of reducing the mechanical de- 
 struction of ties are through the use of tie-plates and improved 
 forms of spikes. 
 
 Tie-Plates. — Tie-plates are designed primarily to (1) distribute 
 the impact and compression of trains over the tie; and (2) absorb 
 the grinding action of the rail. 
 
 If the tie-plate is too light it will soon buckle, or if its bearing 
 surface is too small it will become embedded in the tie. In 
 
 • 'Proceedings A. R. E. and M. of W. Association, Vol. 9, 1908. 
 
142 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 either case the value of the plate is reduced. It is essential, there- 
 fore, to use plates that are strong enough to stand the pressure 
 exerted on them, and that have sufficient surface area to properly 
 distribute the load. Failure to meet these conditions will al- 
 most invariably result in severe mechanical wear on the tie. This 
 is shown in Plate III, Fig. A. 
 
 Many forms of tie-plates are now on the market, but in general 
 plates may be divided into two groups:' (1) Pronged or ridged 
 plates; (2) flat plates. 
 
 In the opinion of some engineers the tie-plates should be so 
 firmly fastened to the tie that they really become part of it. 
 To secure this condition, the bottom of the plate is pronged, 
 ridged, or flanged. (See Plate XIV, Fig. D.) Plates of this type 
 were used in test ties on the Northern Pacific and Chicago and 
 Northwestern experimental tracks laid in cooperation with the 
 U. S. Forest Service. Although they have not been in service long 
 enough to show their real worth, the following points were observed 
 during recent inspections. When the plates are heavily ridged, it 
 takes a very heavy load to embed the ridges and bring the plates 
 down flush with the tie. In the Chicago and Northwestern track, 
 even after 2 years' service, the majority of the ridged plates were 
 elevated about 1/4 inch above the tie. This was due in part to 
 the resistance offered by the ridges to embedment in the wood 
 and in part to sand and gravel which collected under the plate; 
 also, to the fact that the traffic over this portion of the track is 
 now very light. After these plates become firmly embedded they 
 have a tendency to split open the ties, and thus not only weaken 
 them, but furnish catch basins for the retention of rain water. 
 In ties which are difficult to impregnate with preservatives, these 
 checks may extend beyond the zone of treated wood and thus 
 expose the untreated interior of the tie to decay. Another char- 
 
 ' Wooden plates have also been used experimentally, and are being tested 
 by. the U. S. Forest Service in both the Chicago and Northwestern and 
 Northern Pacific tracks. The plates are made of creosoted oak and maple, 
 about five-eighths of an inch thick, 8 inches long, and as wide as the base of the 
 rail. They are inserted between the tie and the rail without any previous 
 adzing, the common practice abroad. The results thus far have been 
 that the plates split badly, and at times have become loose or displaced. 
 In some cases they have embedded themselves into the ties. This is shown 
 in Plate XIV, Fig. C. Although the tests with wooden plates have not as 
 yet been completed, the results thus far secured have not been satis- 
 factory. It is thought, however, that this is largely due to the poor 
 manner in which they were placed. 
 
Plate XIV 
 
 Fig. a. — A good method of piling ties for air seasoning, Port Reading 
 Creosoting Co. (Forest Service photo.) 
 
 Pjq B. White-oak ties seasoned too fast 
 
 (Forest Service photo.) 
 (Facing page 142.) 
 
Plate XIV 
 
 Fig. C. — Ties "protected" with wooden plates. Note plate crushed into 
 tie. (Forest Service photo.) 
 
 Fig. D. — Metal tie plate. (Courtesy Spencer-Otis Mfg. Co.) 
 
PROLONGING THE LIFE OF CROSS-TIES 143 
 
 acteristic of such plates is to grind into the wood fibers, especially 
 of softwood ties such as loblolly pine, cedar, etc. This action 
 also may extend beyond the treated portions of the tie and cause 
 interior rot. These features are unquestionably objectionable, 
 and in some cases may prove of such a serious nature that they 
 will overbalance the good points, such as adherence to the tie 
 and lack of rattling, claimed for plates of this type. 
 
 The objectionable features of pronged or flanged plates are 
 obviated if they are made flat and so rest flush on the surface of 
 the tie. The chief objections to this type seem to be the rattling 
 noise which they make when they are not firmly held to the spikes, 
 and the fact that all resistance to creeping and lateral thrust 
 must be borne entirely by the spikes. The rattling, however, 
 would seem to be an excellent indication that the spikes are loose 
 and need attention. Just how much weight must be attached 
 to the second objection cannot at this time be ascertained from 
 the plates under observation by the U. S. Forest Service. Thus 
 far no creeping or widening of the gauge of the experimental track 
 has been noticed. 
 
 It seems, moreover, in view of the data thus far secured, that 
 of the various forms of tie-plates now under test, those made 
 of metal with a flat bearing surface, or the bearing surface only 
 slightly ridged, are giving better service in protecting the ties 
 from mechanical destruction than those made of metal heavily 
 flanged or pronged. 
 
 A feature which is not a present taken into account, but which 
 unquestionably will be, is the size of tie-plate to be used on 
 different kinds of wood. A softwood tie like loblolly pine is more 
 subject to rail cutting than a hardwood tie like oak, and con- 
 sequently needs a larger tie-plate for its protection. Some tests 
 at the U. S. Forest Products Laboratory of compressive strength 
 of various kinds of ties gave results as shown in Table 12 on 
 pages 144 and 145. 
 
 In other words, shortleaf pine is only about half as strong as 
 red oak and consequently needs a plate with a considerably 
 larger area in order properly to distribute the load. 
 
 Spikes. — The practice of spiking ties to the rail has long been 
 recognized as capable of improvement. The spikes, especially 
 in softwood ties, do not hold firmly, and permit the rail to " creep ' ' 
 and "pump," thus greatly shortening the life of the tie. Fur- 
 thermore, they tear the wood-fibers, work loose, and permit rain 
 
144 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 Table 12.^CBTrsHiNG Strength op Cross-ties in Percent of White 
 
 Oak 
 
 Kind of tie 
 
 Common name 
 
 Botanical name 
 
 Fiber stress 
 at elastic 
 limit per- 
 pendicular, 
 
 to grain, lb. 
 per sq. in. 
 
 Fiber stress 
 in percent 
 of white oak, 
 or 853 lb. 
 per sq. in. 
 
 Osage orange 
 
 Honey locust 
 
 Black locust 
 
 Post oak 
 
 Pignut hickory ..... 
 
 Water hickory 
 
 Shagbark hickory . . . 
 Mockernut hickory.. 
 Big shellbark hickory. 
 Bitternut hickory. . . . 
 
 Nutmeg hickory 
 
 Yellow oak 
 
 White oak 
 
 Bur oak 
 
 White ash 
 
 Red oak 
 
 Sugar maple 
 
 Rock elm 
 
 Beech 
 
 Slippery elm 
 
 Redwood 
 
 Bald cypress 
 
 Red maple 
 
 Hackberry . . 
 
 Incense cedar 
 
 Hemlock 
 
 Longleaf pine 
 
 Tamarack 
 
 Silver maple 
 
 Yellow birch 
 
 Tupelo 
 
 Black cherry 
 
 Sycamore 
 
 Douglas fir 
 
 Cucumber tree 
 
 Shortleaf pine 
 
 Red pine 
 
 Sugar pine 
 
 White elm 
 
 Western yellow pine. , 
 
 Toxylon pomiferum . . 
 Gleditsia triacanthos . 
 Robinia pseudacacia. 
 
 Quercus minor 
 
 Hicoria glabra 
 
 Hicoria aquatica 
 
 Hicoria ovata 
 
 Hicoria alba 
 
 Hicoria laciniosa 
 
 Hicoria minima 
 
 Hicoria myristicaeformis 
 
 Quercus velutina 
 
 Quercus alba 
 
 Quercus macrocarpa. . 
 Fraxinus americana. . . 
 
 Quercus rubera 
 
 Acer saccharum 
 
 Ulmus 
 
 Fagus atropunicea . . . 
 Ulmus pubescens. . . . 
 Sequoia sempervirens . 
 Taxodium distichum. . 
 
 Acer rubrum 
 
 Celtis occidentalis .... 
 Libocedrus decurrens . 
 
 Tsuga canadensis 
 
 Pinus palustris 
 
 Larix lariciana 
 
 Acer saccharinum. . . . 
 
 Betula Lutea 
 
 Nyssa aquatica 
 
 Prunus serotina 
 
 Platanus occidentalis.. 
 Pseudotsuga taxif olia . 
 Magnolia acuminata. . 
 
 Pinus echinata 
 
 Pinus resinosa 
 
 Pinus lambertiana 
 
 Ulmus americana 
 
 Pinus ponderosa 
 
 2,260 
 1,684 
 1,426 
 1,148 
 1,142 
 1,088 
 1,070 
 1,012 
 997 
 986 
 938 
 857 
 853 
 836 
 828 
 778 
 742 
 696 
 607 
 599 
 578 
 548 
 531 
 525 
 618 
 497 
 491 
 480 
 456 
 454 
 451 
 444 
 433 
 427 
 408 
 400 
 358 
 353 
 351 
 348 
 
 265.0 
 
 197.5 
 
 167.2 
 
 134.6 
 
 133. 
 
 127. 
 
 125. 
 
 118. 
 
 116.9 
 
 115.7 
 
 110.0 
 
 100,5 
 
 100.0 
 
 98.0 
 
 97.1 
 
 91.2 
 
 87.0 
 
 81.6 
 
 71.2 
 
 70.2 
 
 67.8 
 
 64.3 
 
 62.3 
 
 61.6 
 
 60.8 
 
 58.3 
 
 57.6 
 
 56.3 
 
 53.5 
 
 63.2 
 
 62.9 
 
 52.1 
 
 50.8 
 
 60.1 
 
 47.8 
 
 46.9 
 
 42.0 
 
 41.4 
 
 41.2 
 
 40.8 
 
PROLONGING THE LIFE OF CROSS-TIES 
 
 145 
 
 Table 12. — Cetjshing Strength of Cross-ties in Percent of White 
 
 Oak. — Continued. 
 
 Kind of tie 
 
 Fiber stress 
 
 at elastic 
 
 limit per- 
 
 pendioulaa, 
 
 to grain, lbs. 
 
 per sq. in. 
 
 Fiber stress 
 in percent 
 of wbite oak, 
 or 853 lb. 
 per sq. in. 
 
 Common name 
 
 Botanical name 
 
 Lodgepole pine 
 
 Red spruce 
 
 Pinus contorta 
 
 348 
 345 
 314 
 290 
 288 
 269 
 262 
 258 
 210 
 209 
 193 
 
 40.8 
 40.5 
 36.8 
 34.0 
 33.8 
 31.5 
 30.7 
 30.3 
 24.6 
 24.5 
 22.6 
 
 Picea rubens 
 
 White pine 
 
 Pinus strobus 
 
 Engelmann spruce . . . 
 
 Picea engelmanni 
 
 Thuja occidentalis 
 
 Populus grandidentata. 
 
 Picea canadensis 
 
 Juglans cinerea 
 
 Largetooth aspen 
 
 White spruce 
 
 Butternut 
 
 Buckeye (yellow) 
 
 Basswood 
 
 Aesculus octandra 
 
 Tilia americana 
 
 Salix nigra 
 
 Black willow 
 
 
 to collect and decay to start. This necessitates a rather frequent 
 respiking of the rail, which often fills the tie with holes to such 
 an extent that it is "spiked to death" and must be removed. 
 It was thought that by first boring a hole into the tie and then 
 driving the spike into it, the fibers would not be torn and then the 
 spike would hold more firmly. (See Plate XII, Fig. C .) Tests 
 were made^ in which ordinary 9/16-inch square spikes were driv- 
 en into red-oak ties previously bored with holes 3/8, 7/16, and 
 1/2 inches in diameter. Although the spikes were driven by an 
 experienced trackman, in over half the cases they failed to follow 
 the holes. Their resistance to pulling was thus reduced. When 
 no hole was bored the average force required to pull the spikes 
 was 8827 pounds; when bored in the manner above described 
 the respective forces were 8050, 8106, and 7154 pounds. In order 
 to overcome the objection mentioned the spikes were pointed on 
 four sides, and when this was done there was no difficulty what- 
 ever in getting them to follow the holes. Furthermore, their 
 resistance to vertical pull was increased and the wood-fibers 
 were not seriously torn. The number of pounds required to pull 
 pikes from red-oak ties was as follows :^ 
 
 1 By J. A. Newhn, in charge of timber tests, Forest Products Laboratory. 
 
 ' It will be noticed that the spikes driven in the first test held more firmly 
 than those driven in the second. For example, when no hole was bored it 
 took 8827 pounds to pull them in the first test and only 7613 pounds in the 
 10 
 
146 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 Pounds 
 
 Ordinary 9/16-mch square spikes driven without boring 7613 
 
 Ordinary 9/16-incli square spikes pointed on four sides, driven in 
 
 hole 3/8 inch in diameter 8178 
 
 Ordinary 9/16-inch square spike pointed on four sides, driven in 
 
 hole 7/16 inch in diameter 7856 
 
 Ordinary 9/16-inch square spike pointed on four sides, driven in 
 
 hole 1/2 inch in diameter 7664 
 
 When the diamond-pointed spikes were driven into the .tie 
 without first boring holes, the ties were almost invariably split. 
 It appears, therefore, that they cannot be used satisfactorily 
 ■without previous boring. 
 
 Some of the ties used in these tests were treated with creosote, 
 others with zinc chloride, and still others were left untreated, 
 but no appreciable difference due to treatment was noticed. 
 In a few cases a heavy oil was poured into the holes and allowed 
 to soak for 16 hours before the spikes were driven. The resist- 
 ance to pull was decreased from 7644 to 6628 pounds. While no 
 tests were made, it is quite possible that if the holes are bored into 
 the ties before they are treated the resistance of the spike will be 
 less than if they are bored after treating. In spite of this, how- 
 ever, it is believed that if holes are bored at all they should be 
 bored before and not after treatment, since in the former case the 
 ties will be fully protected against rot. 
 
 While the tests described show that boring holes into ties pre- 
 vious to spiking them is an improvement over the common prac- 
 tice in this country, experience abroad leads to the conclusion 
 that even better results can be obtained by the use of screw 
 spikes. To secure data for American operating conditions, 
 screw spikes were used by the U. S. Forest Service in the Northern 
 Pacific, Chicago & Northwestern, and Chicago, Milwaukee & 
 St. Paul test tracks. In laying the Northern Pacific and Chicago 
 & Northwestern tracks no screw-spike boring or driving machine 
 was available, so that the holes had to be bored and the spikes in- 
 serted by hand. In some cases the holes were not bored deep 
 enough, and the point of the spike struck the base of the hole. 
 On further tightening the spike the threads in the wood were 
 destroyed. Furthermore, the holes were not in all cases bored 
 
 second. This cannot be attributed to any difference in the spikes, but to the 
 ties into which they were driven. Also, in the latter case the spikes were 
 pulled soon after they were driven. The two series of tests, therefore, are not 
 comparable with each other. 
 
PROLONGING THE LIFE OF CROSS-TIES 147 
 
 vertically, so that the spikes were inserted at various angles. 
 When the Chicago, Milwaukee & St. Paul track was put in place, 
 a screw-spike boring and driving machine was used, and the 
 difficulties previously encountered were done away with. The 
 machine drove the holes vertically and to a uniform depth, so 
 that the spikes all had proper alignment and clearance. In 
 every case the machine drove the spikes firmly into the tie. 
 
 The screw spikes used in the Northern Pacific and Chicago & 
 Northwestern test tracks were driven through plates which did 
 not reenforce the head of the spike against lateral thrust. After 
 3 years' service many of the these spikes were badly bent, 
 resulting in a widening of the track gauge. In laying the Chicago, 
 Milwaukee & St. Paul track, a plate with bosses for supporting 
 the heads of the spikes was used, which it is believed will mate- 
 rially increase their holding power. 
 
 In a large number of tests made at Purdue University, a part 
 of which were conducted by the U. S. Forest Service,' it was 
 found that screw spikes had from 1.7 to 3.8 times the strength of 
 the common spike against pull, and from 1.2 to 2.4 times the lat- 
 eral resistance of the common spike. The heads of the spikes 
 were not supported in these tests. 
 
 An objection raised against the use of screw spikes is that it 
 takes longer to insert them than to insert cut spikes, and that this 
 at times delays the passage of fast trains. In laying the Chicago, 
 Milwaukee & St. Paul test track this objection was partially 
 overcome by spiking every third tie throughout the rail length, 
 which permitted trains to pass, and afterward spiking the re- 
 maining ties. 
 
 A further objection to the use of screw spikes is the difficulty 
 of regauging the track when the rail- becomes worn. It is pos- 
 sible that this objection may in time be overcome by altering the 
 design of plates used with this type of spike. 
 
 While the use of screw spikes in this country is still in its in- 
 fancy and final judgment cannot as yet be pronounced, it gives 
 promise of overcoming the objections raised against the ordinary 
 cut spike. If it succeeds in this it will unquestionably result in 
 greatly reducing the mechanical destruction of ties. 
 
 Adzing and Boring Ties. — In Chapter VII lit was stated that 
 adzing and boring ties prior to treatment was]good practice, and 
 
 1 Fourth Progress Report of Tests on Treated Ties, by W. K. Hatt, 
 Purdue University, Bulletin 124, A. R. E. and M. of W. Assn. 
 
148 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 the data given above show how the holding power of spikes can 
 be increased by driving them through such holes. Of equal 
 importance is a proper bearing of the rail or plate on the tie, for 
 if this is not done the wear will be concentrated over a small 
 area and the mechanical destruction of the tie hastened. Further- 
 more, it is felt that the unequal bearing of rails on ties can be 
 held responsible, in part at least, for breaking the rail, especially 
 during cold weather. Adzing prior to treatment not only en- 
 ables the plate'and rail to be firmly and uniformly fastened to the 
 tie, but makes it possible to at least coat with preservative that 
 portion of the tie most subject io wear. For these reasons 
 adzing and boring of ties are highly commended. 
 
 The Selection of Processes for Treating Ties. — The wide 
 range of conditions under which cross-ties are used makes a 
 selection of treating processes necessary if most economic results 
 are to be secured. Lack of specific data on the exact value of the 
 various processes prevents a clear-cut decision as to which is best 
 for a given set of requirements. 
 
 The ideal treatment is one in which the ties fail from decay 
 and wear at the same time. If the failures are caused by decay, 
 then a more efficient preservative should be used; if, on the other 
 hand, the failures are caused by wear which cannot be prevented, 
 then a less efficient treatment should be used. It can be readily 
 seen that any process which puts into ties more preservative 
 than is necessary to protect them longer than their mechanical 
 life is a wasteful process, because after the ties are removed from 
 the track the'^preservative in them is useless. The proper balance 
 between the failure of a tie from decay and from wear is a very 
 difficult one to obtain with our present limited fund of data 
 and this complicates greatly the selection of a proper treating 
 process. Certain general rules can, however, be laid down which 
 should aid in selecting the proper process for any given condi- 
 tions. The most important points to consider in this connection 
 are : (1) kind and form of ties to be used, (2) the tonnage over the 
 road, (3) climatic conditions, and (4) type of track construction. 
 These are so closely interwoven that they must all be considered 
 together. 
 
 If the road is so fortunate as to run through or tap a forested 
 region containing strong, durable tie material, the need of a 
 preservative treatment is not pressing and may even be dispensed 
 with entirely. Thus, if ties of heart cypress, redwood, and cedar 
 
PROLONGING THE LIFE OF CROSS-TIES 149 
 
 can be obtained at a reasonable price, no treatment other than 
 a protection from wear is required. However, this condition 
 rarely exists, so that some method of increasing the resistance 
 of the wood to decay becomes necessary. If the wood is refrac- 
 tory — that is, if a preservative cannot be forced into it except 
 superficially — as with Douglas fir, tamarack, etc., as heavy a 
 treatment as possible with straight creosote will probably give 
 most efficient results because even at best only small amounts 
 of the oil will be absorbed. If, however, the wood is porous and 
 readily absorbs preservative, then some cheaper process, like the 
 Burnett, Card, or empty-cell creosote is preferable. The same 
 is true for those ties which are cut so as to have fairly wide strips 
 of sapwood on one or both sides while the faces are of resistant 
 heartwood possessing in itself little durabihty. 
 
 Obviously, ties which have a heavy tonnage passing over them 
 are more subject to failure from wear than ties laid in a track 
 where the tonnage is light. In general, such ties should be given 
 a less efficient and expensive treatment, for if heavy injections 
 are made, considerable quantities of preservative will be destroyed 
 with the ties. 
 
 Climatic conditions must be carefully considered. Ties laid 
 in regions of heavy rainfall had best be treated with straight 
 creosote. In arid regions and where rainfall is comparatively 
 light, zinc-treated ties may be advantageously used. 
 
 The type of track construction has much to do with the selec- 
 tion of the process. In general, best construction enables the 
 use of the more effective and expensive treating processes. For 
 example, a track laid with heavy rail, heavy tie plates, screw 
 spikes and a firm rock ballast would call for a more costly and 
 effective treating process than one laid with cut spikes, dirt 
 ballast, and no tie plates. It should not follow that this is uni- 
 versally true. Suppose, for instance, that the track construction 
 is of the best, but that the ties are of a comparatively soft wood 
 like loblolly pine; it is the author's opinion that an empty-cell 
 process should be selected in preference to a full-cell, as it would 
 give an equal length of life to the tie with a much less consump- 
 tion of preservative, and hence the expense would be less. As 
 mentioned above, a decision on the selection of a proper timber- 
 treating process for ties can be correctly made only after all fac- 
 tors affecting the life of the tie have been considered. It appears, 
 therefore, that railroads controlling a large mileage, especially, 
 
150 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 if it traverses a wide territory, should use more than one process 
 in order to secure most economic returns. In the above discus- 
 sion, the question of initial cost has not been mentioned, as its 
 effect in the selection of a process is so obvious as to need no special 
 comment. The ideal process selected may be the cheapest 
 process — Burnettizing, for example — in so far as initial cost is 
 concerned. Or the ideal process may be the most expensive — ■ 
 full-cell creosote — in which case, if the company could not afford 
 it, the next best rather than none at all should be selected. A 
 common feature is that practically all standard processes using 
 pressure pay if compared to the use of untreated ties, so the 
 problem reduces itself largely to a question of which pays best. 
 
 Cost of Treating Ties.- — The total cost of treating ties can be 
 divided into the following general items : (1) seasoning, (2) labor, 
 (3) fuel, (4) plant operation and maintenance, and (5) chemicals. 
 
 The majority of ties now treated in the United States are air- 
 seasoned prior to treatment. The cost of this varies with the 
 kind of wood, season of the year, and geographical location. 
 In general, however, seasoning charges range from about 0.50 to 
 1.5 cents per tie. 
 
 Labor includes all forms necessary to the treatment, such as 
 loading and unloading of ties in the yard, and for the tie plant 
 and superintendence. It also varies considerably, but ranges 
 from about 3 to 6 cents per tie. 
 
 Fuel is least in those plants which can use natural gas or oil and 
 highest in those most remote from a source of supply, but ranges 
 from about 1/2 to 2 cents per tie. 
 
 On account of the corrosive action of zinc chloride, the life 
 of a plant using that kind of a preservative is usually reckoned as 
 shorter than that of one using creosote; consequently, its de- 
 preciation is greater. If the capacity of the plant is lowered 
 through accident, shortage of ties, etc., the depreciation charges 
 per tie will be very high. The total cost of maintenance, includ- 
 ing this depreciation, interest on the investment, etc., will usu- 
 ally range from 1 to 2 cents per tie. 
 
 Practically all pf the ties now treated in commercial plants in 
 the United States are injected with zinc chloride or with creosote, 
 either alone or in combination. Only a few plants use preserva- 
 tives like crude oil and mercuric chloride. It is customary to 
 inject about 1/2 pound of dry zinc chloride per cubic foot 
 of wood although this varies at times from one-third to two- 
 
PROLONGING THE LIFE OF CROSS-TIES 151 
 
 thirds of a pound. This salt costs from 3 1/2 to 5 cents per 
 pound. Creosote costs from about 7 to 12 cents per gallon in 
 large quantities. It is customary in tie work to inject from 5 to 
 10 pounds of this oil per cubic foot. 
 
 With the above data the cost of tie treatments may be esti- 
 mated. It should be borne in mind, however, that the figures 
 given are general, and will not apply to all conditions. Using 
 them as a basis, however, the cost of treating a standard 7 inch 
 X 9 inch X 8 foot tie will be approximately as shown in 
 Table 13, royalties not included. It is understood that royalties 
 are now charged in the Rueping and Card processes, while the 
 Lowry process is operated under certain restrictions by the com- 
 pany which controls the Lowry patents. For the other proc- 
 esses listed in the table no royalties are required. 
 
 Table 13. — ^Approximate Cost of Treating Ties 
 
 (Tie 7 inches X 9 inches X 8 feet) 
 Process ~ | Cost per tie, cents 
 
 Burnett 
 
 Wellhouse 
 
 Card 
 
 Rueping(a) 
 
 LowTy(6) 
 
 Full-cell cresote(c). 
 
 10-14 
 12-16 
 16-20 
 25-29 
 32-35 
 39-45 
 
 a = Etssuming about 6 pounds of creosote per cubic foot absorption. 
 6 = assuming about 8 pounds of creosote per cubic foot absorption, 
 c = assuming about 10 pounds of creosote per cubic foot absorption. 
 Assuming creosote costs about 1 cent per pound and zinc chloride about 
 4 cents per pound. 
 
 It will be noted in this table that the cost of the preservative 
 used is a large percentage of the total cost of treatment. Creo- 
 sote, for example, greatly increases the cost of the treatment and 
 when it is used in comparatively large quantities — 8 pounds or 
 over per cubic foot — all other costs make but a small fraction in 
 the total cost of treatment. The opportunity either for an effi- 
 cient preservative at lower cost or for some modified method of 
 operation which will enable a high-priced preservative to be 
 better utilized than is being done in present practice is strik- 
 ingly apparent. 
 
 Economy in Treating Ties. — There is no longer any just doubt 
 but what the preservative treatment of ties pays. Unfortunately, 
 
152 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 reliable records on the life of treated ties which have been in ser- 
 vice for long periods are too meager to enable exact estimates of 
 actual economy to be made, so that the financial saving is still a 
 matter of conjecture. Because of this condition it is not pos- 
 sible to state what process of treatment is most economical, 
 and it will take several years before any true basis for such state- 
 ments will be warranted. As has already been pointed out, 
 it is quite likely that the different methods of treatment now 
 practised will be found to have rather sharp limitations so that 
 they will not overlap and compete to such a large degree as at 
 present. The different kinds of ties, the different types of con- 
 struction, and the different geographical regions traversed by 
 our roads will demand different treatments. 
 
 In the meantime, the best that can be done is to use what 
 data is already available on treated and untreated ties in service, 
 and add to this our knowledge on the efficiency of the various 
 preservatives used, the action of wood-destroying fungi, and the 
 durability and susceptibility to treatment of the various woods 
 now used for manufacture into ties. 
 
 While the saving in money is undoubtedly the most important 
 feature which the railroads will consider, nevertheless it is be- 
 lieved that other factors should not be overlooked. If a process 
 showing lowest annual charges is selected, it may be it does not 
 prolong the life of the ties as much as some other process having 
 higher annual charges. This means that tie removals will be 
 more frequent and the roadbed will consequently be more con- 
 tinuously disturbed. The disadvantages are obvious. Further- 
 more, if the price of untreated ties shows a steady advance, the 
 advantage of securing as long a life as possible from them is 
 readily apparent. 
 
 Because of the many factors which influence the economy 
 resulting from treating ties and because of the uncertainty of 
 present data on the durability of ties, estimates on saving are 
 here given for only two processes — the Burnett and full-cell 
 creosote — as these represent the probable extremes, certainly in 
 so far as initial cost is concerned. In order to make the results 
 comparable, it is assumed that all ties are plaled, the plates cost- 
 ing 25 cents per tie, and that the cost of placing the ties in the 
 track is 15 cents. Furthermore, all ties are subjected to the same 
 traffic conditions and preliminary treatment. As annual charges 
 best show resulting economy they are used in the following table 
 
PROLONGING THE LIFE OF CROSS-TIES 
 
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154 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 and are figured on the cost of the ties in the track, the computation 
 being made by the following formula: 
 
 '' ~ ^ i.or - 1 
 
 Where r = equivalent annual charge. 
 
 R = initial expenditure, 
 
 p = rate of interest (taken as 5 percent). 
 
 n = term of years. 
 
 It will be noted that, in general, the ties treated with creosote 
 show a slightly greater economy than when treated with zinc 
 chloride. In this connection, however, the remarks already 
 made concerning the selection of the treating process should be 
 kept in mind; that is, ties treated with zinc chloride should not 
 be laid in wet localities. If ties treated by this method are laid 
 in such regions the differences shown in the table would, of course, 
 be considerably greater. 
 
 It should be noted that greatest economy in treating ties comes 
 from those which possess little durability in an untreated condi- 
 tion, this amounting in certain cases to an annual saving of over 
 20 cents per tie per year. Least saving comes from ties which 
 are resistant to treatment and which do not possess a marked 
 natural durability. Such ties ought not to command high prices. 
 In fact, it is exceedingly likely that the prices now paid for ties 
 will be readjusted as reliable data on their serviceability is grad- 
 ually obtained, and more value is placed upon their intrinsic 
 properties. Red oak, beech, and elm, for example, will become 
 more and more prized as good tie woods, because of their rapid 
 growth, hardness, and permeability. 
 
 If the figures given in the table are found by actual experience 
 to be accurate, the difference in the annual saving between the 
 two processes compared is insignificant. This does not mean, 
 however, that the selection of the process is unimportant, because 
 other factors such as initial cost, ultimate length of service, local 
 climatic conditions, etc., as pointed out above, must also be taken 
 into consideration. 
 
 Need for Test Tracks. — It is apparent from the above discus- 
 sion on the economy of treatment that little of definite value on 
 the efficiency of various processes can be determined until ac- 
 curate data is available. Without doubt, the best way of secur- 
 ing such data is to set aside certain portions of the main track, 
 
PROLONGING THE LIFE OF CROSS-TIES 155 
 
 typifying conditions of the road, for experimental or test purposes. 
 Such portions of the track are called "test or experimental 
 tracks." In them complete records should be kept on each tie, 
 such as kind of wood, how treated, when and how laid, and notes 
 on its character of failure obtained from yearly inspections. In 
 addition, general data on the character of the ballast, type of 
 construction, tonnage over the road, etc., should be made a matter 
 of record. To assist in identifying the ties, each tie should have 
 zinc-coated datingnails driven into it at some readily accessible 
 point. A good place for the nails is about 1 foot inside the rail. 
 
 The old method of driving dating nails into all treated ties and 
 attempting to keep records on all of them has not proved success- 
 ful and is not recommended. Trackmen as a rule will not keep 
 accurate records and unless the records are accurate they are 
 worse than useless, as they may lead to absurd conclusions. 
 The direct and positive value of the data secured from test tracks 
 enables accurate deductions to be made of the efficiency of the 
 treatment and far more than justifies the cost of placing and 
 maintaining them. 
 
CHAPTER IX 
 
 PROLONGING THE LIFE OF POLES AND CROSS ARMS 
 FROM DECAY AND INSECTS 
 
 POLES 
 
 Selection of Species. — According to present usage, in order to 
 make a satisfactory pole, a tree must have the following general 
 properties: Its wood must be strong, comparatively light in 
 weight and durable, its taper must be gradual and well defined, 
 its form must be straight, and in addition its supply must be 
 accessible and abundant. These requirements necessarily re- 
 strict the number of species which can be used. For example, 
 of the 3,000,000 poles consumed annually in the United States, 
 over two-thirds are cedar and about one-seventh chestnut. 
 Hence, over 80 percent are cut from only two kinds of wood. 
 
 If the preservative treatment of poles was more generally 
 practised, a much larger variety of woods could be drawn upon, 
 since they possess all of the requisite properties save durability. 
 It seems apparent, therefore, that as the present supply of "pole 
 woods" becomes more and more exhausted the need for preserva- 
 tive treatment will increase. Such woods as the pines, spruces, 
 and firs should prove admirably adapted for poles, and they will 
 undoubtedly be called into use. In fact, a movement in this 
 direction has already taken place, and poles cut from these timbers 
 are now being used in several places in the West. 
 
 Insects, in addition to decay, also attack poles, thus weakening 
 them not only by their burrows but also by admitting channels 
 through which the decay can enter and spread. As the methods 
 which prevent decay will also prevent insect attack, the two are 
 discussed in common in this chapter. 
 
 Manufacture of Poles. — Most of the poles used in the United 
 States are simply tree trunks which have been trimmed of limbs 
 and then peeled. Very few sawed poles are used. As has already 
 been pointed out (Chapter IV) the best time to cut timber is in 
 winter or late fall. Poles cut during this period are, however, 
 more difl&cult to peel, as the bark clings tenaciously to them, 
 
 156 
 
PROLONGING THE LIFE OF POLES 157 
 
 whereas in spring long strips of bark can readily be torn from the 
 trunk. It is very important to peel all bark from that portion 
 of the pole to be treated; otherwise the bark will prevent a uni- 
 form penetration of the preservative. 
 
 The practice of dragging poles over the ground for long dis- 
 tances, thereby grinding off the outer layers of wood, should be 
 prohibited, as it not only weakens the pole but makes it more 
 susceptible to decay. 
 
 It is also bad practice to saw that portion of the pole which 
 projects above ground, leaving the butt the natural shape and 
 size of the tree, unless the butt is given a thorough preservative 
 treatment, because the sap on the butt will quickly decay and 
 infect the heartwood. If sawing must be done on account of 
 local or other requirements, it is better to saw the entire pole. As 
 a general proposition, however, sawing should be avoided if pos- 
 sible. The top of the pole should also be cut slanting unless 
 there is some reason why this cannot be done. If a plate or cap 
 is placed on the top of the pole, the wood underneath should be 
 at least brush treated with creosote. Whenever possible the 
 pole should be trimmed and bored to exact dimensions before 
 it is treated, in order to avoid cutting into the treated wood and 
 thus exposing the untreated interior. 
 
 Method of Seasoning. — Common practice now pays little at- 
 tention to seasoning poles. (See Plate XV, Fig. A.) Poles are gen- 
 erally piled one on top of the other in order to occupy as little 
 space as possible. If the poles are not to be treated and if they 
 are not held too long in these piles so that decay will attack them, 
 no serious objection can be levied against this practice. Of 
 course, when piled in this manner, the rate at which they lose 
 water is greatly decreased and consequently they will weigh 
 more when shipped; hence, the cost of transportation is 
 increased. 
 
 If the poles are to be treated, especially by the open-tank or 
 brush methods, a preliminary air seasoning is highly desirable. 
 The best way to do this is to roll the poles on skids with suf- 
 ficient space between them so that the air can circulate freely. 
 These skids can be built of poles placed horizontally and ele- 
 vated a foot or more above the ground. If ^pace permits, but 
 one layer of poles should be built on each skid, but if necessary, 
 several layers can be piled on each other. (See Plate XV, Fig. B.) 
 
 Factors other than ease of handling should be given con- 
 
158 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 sideration in selecting the seasoning yard. For example, the 
 ground should be fairly level, well drained, and as free from weeds 
 and decayed wood as possible. The poles should be exposed to 
 the sun and air currents so that the seasoning will be rapid. 
 Too rapid seasoning, however, may check the poles, in which 
 case they can be piled closer together. Incipient checks, which 
 are liable to increase in size, should be protected with "S-irons" 
 (Fig. 22). 
 
 The length of time poles should be seasoned varies primarily 
 with the time of year, the kind of wood, and climatic conditions. 
 
 Fig. 22. — Method of applying "S "-irons to prevent checking. 
 
 From a large number of tests made by the U. S. Forest Service 
 in cooperation with the American Telephone and Telegraph 
 Company the following table has been compiled : 
 
 Table 15. — Approximate Time Reqtjibed to Air Season Poles for 
 
 Treatment 
 
 Species 
 
 Eegion 
 
 No. of months requii^d when poles 
 are cut in 
 
 Spring 
 
 Summer 
 
 Autumn 
 
 Winter 
 
 Chestnut 
 
 Southern white cedar .... 
 Northern white cedar. . . . 
 Western yellow pine 
 
 Maryland 
 
 Carolinas 
 
 Michigan 
 
 California 
 
 3 
 2 
 5 
 5 
 
 3 
 2 
 5 
 2 
 
 7 
 4 
 9 
 9 
 
 6 
 3 
 8 
 6 
 
 The above figures may be used to predict the seasoning periods 
 for other varieties of wood not hsted, although just how accurate 
 they will be cannot be told except by actual trial. 
 
 Because of its comparatively large diameter, the moisture 
 content of an "air-seasoned" pole varies considerably. For 
 example, the outer portion may contain only 10 percent of moisture 
 
Plate XV 
 
 Fig. A.-Cedar poles piled for storage, Michigan. (Forest Service photo.) 
 
 Fig. B. — -Poles properly piled for air seasoning, Black Forest, Germany. 
 (Forest Service photo.) 
 
 (.Facing page 158.) 
 
Plate XV 
 
 Fig. C — An open tank pole treating plant. A poor design, note creosote 
 evaporating from tanks. (Forest Service photo.) 
 
 Fig. D. — Creosoted poles for heavy construction, Hayes, England. (Forest 
 
 Service photo.) 
 
PROLONGING THE LIFE OF POLES 
 
 159 
 
 while the interior has 40 percent or over. It is not necessary 
 or practicable to reduce this interior moisture very materially, 
 for it does not seriously affect any preservative treatment which 
 might be given. 
 
 The effect of this moisture loss on freight shipments is very 
 important, especiallv in long hauls. 
 
 Table 16. — Showing Saving in Fbeight Effected by Aik-seasoning 
 
 Poles 
 
 Species 
 
 Size of pole 
 
 No. of 
 poles re- 
 quired for 
 carload of 
 40,000 
 lb. 
 
 Total de- 
 crease in 
 weight due 
 
 to air 
 seasoning 
 (pounds) 
 
 Saving in freight on 
 carload lots 
 
 Length, 
 feet 
 
 Top 
 diam- 
 eter, 
 in. 
 
 25 cent 
 rate, 
 dollars 
 
 15 cent 
 rate, 
 dollars 
 
 Chestnut 
 
 30 
 30 
 30 
 40 
 40 
 
 7 
 7 
 
 I 
 
 8 
 
 43 
 
 74 
 91 
 59 
 46 
 
 7,700 
 16,900 
 12,800 
 12,900 
 38,400 
 
 19.25 
 42.25 
 32.00 
 32.25 
 96.00 
 
 11.55 
 25.35 
 19.20 
 19.35 
 57.60 
 
 Southern white cedar. 
 Northern white cedar . 
 Western red cedar .... 
 Western yellow pine. . . 
 
 The decrease in weight from a green to an air-dry condition 
 varies from about 20 to 50 percent, or 180 to 850 pounds per pole. 
 The decrease in shipping weight and freight charges is, of course, 
 in direct proportion to these percentages. 
 
 The shrinkage in the circumference of poles due to their season- 
 ing is insignificant, contrary to general belief. Consequently, 
 if a pole is measured when green, these figures can be considered 
 as practically unaltered by subsequent drying, since the shrinkage 
 will not exceed 1 percent. Exact data on shrinkage taken 
 from measurements on about 2000 poles of chestnut, cedar and 
 pine averaged from 0.3 to 0.5 percent of the green circumference 
 6 feet from the butt to 0.6 to 0.9 percent at the top. This is 
 equivalent on 30- to 40-ft. poles to about 0.1 or 0.2 inch in 
 the circumference of the butt and from 0.15 to 0.25 inch at 
 the top. 
 
 If the poles are steam seasoned, they are handled in much the 
 same manner as cross-ties, viz., placed in the treating cylinder 
 and subjected to live steam at pressures not exceeding 40 pounds 
 for four or more hours, after which a vacuum is applied and the 
 preservative injected. 
 
 Methods of Treatment and Their Selection. — ^Because of 
 their large size and the high cost of handling and shipping them 
 and the comparatively small number assembled at one point, 
 
160 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 the treatment of poles is quite a different problem from the treat- 
 ment of ties. Furthermore, poles vare not subject to the same 
 kind of deterioration as ties. That portion which projects above 
 ground is much less subject to decay than that in the ground, 
 and in temperate climates like the northern and western United 
 States, where the humidity and temperature are generally low, 
 the tops may last indefinitely. In warm, humid climates, as in 
 the South, a protection to the top is desirable and often — as in 
 the case of pines — necessary. Poles do not fail from mechanical 
 wear, so that this factor need not be considered. 
 
 Several methods of protecting the life of poles from decay and 
 insects — the chief destructive agents^ — are practised. These are 
 (1) setting the poles in crushed stone or concrete, (2) charring the 
 butts, (3) brush treating the butts with a wood preservative, 
 (4) impregnating the butts with a preservative, and (5) impreg- 
 nating the entire pole with a preservative. 
 
 Setting in Crushed Stone or Concrete. — If the hole into which 
 the pole is to be placed is dug several inches wider than the pole, 
 crushed or small field stones can be pounded around the pole 
 after it is set. These will permit more or less circulation of air 
 around the butt and keep weeds from growing close to the pole. 
 In this way a partial protection is afforded which will add a year 
 or two to the life secured. Furthermore, the stones will tend to 
 protect the pole from ground fires. Sand placed in such holes 
 affords no protection and may even hasten decay. The author has 
 little evidence that poles set in concrete are materially prolonged 
 in service. Such concrete jackets are liable to become broken 
 and hence admit water. All of these methods are considered 
 make-shifts and should be used only when no better treatment 
 can be had. 
 
 Charring. — Provided the poles are air seasoned, charring to a 
 depth of 1/4 in. from the butt to about 2 ft. above ground line 
 will more than pay for itself. It is, however, an inefficient 
 method of treatment and adds but little to the life of the pole. 
 If charred green, the poles are very liable to check open and de- 
 cay hastened rather than retarded. Charring, furthermore, 
 destroys the outer fibers of the wood and weakens the pole where 
 strength is most needed. Charred poles examined by the author 
 were also readily attacked by insects. 
 
 Brush Treatment. — These should be applied to poles only 
 after they are air seasoned. If applied to green poles, the effec- 
 
PROLONGING THE LIFE OF POLES 161 
 
 tiveness of the treatment will be greatly decreased. The methods 
 of applying brush treatments have already been described (see 
 Chapter V). To secure best results, particularly for poles set in 
 sandy soil, the entire butt and end of the pole should be coated 
 with the preservative and the protection should extend 1 or 
 2 feet above the ground line. If poles are well treated by this 
 method, their life can be extended from 3 to 6 years. When 
 no better method can be afforded, brush treatments are recom- 
 mended. The best preservative thus far known is coal-tar 
 creosote, which should be applied hot (about 160° F.) in two 
 coats. For reliable results secured to date the reader is re- 
 ferred to Fig. 118, appendix. 
 
 Open-tank Butt Treatments. — If the top of the pole is not 
 subject to decay, a butt treatment in an open tank is the best 
 known. (See Plate XV, Fig. C.) (For description see open-tank 
 treatment. Chapter V.) A number of test poles treated in 
 this manner have shown excellent results (see Fig. 31 and Fig. 32, 
 appendix), and because the preservative is confined to the 
 butt of the pole where decay is most active, the method is 
 more economical than if the entire pole is impregnated. Un- 
 fortunately, in order to cut down labor and maintenance costs, 
 such treatments are feasibly only where comparatively large 
 numbers of poles are assembled at one point. Furthermore, the 
 treatment may mean a delay in shipment, although it is felt 
 that this objection should be met on the part of pole consumers 
 by anticipating their orders in sufficient time to enable the 
 treatment to be made. 
 
 Coal-tar creosote to the amount of 10 pounds per cubic foot, 
 or more if possible, will give best results. It is possible, how- 
 ever, to impregnate the butts with zinc chloride or other 
 antiseptic salts, either alone or in combination with the creosote, 
 in which case a decrease in the cost of the preservative can be 
 made. In any event, the aim should be to treat all of the 
 sapwood to a height of 1 to 2 feet above ground level. 
 
 Butt treatments are now given which often amount to little 
 more than dipping treatments, and while they are better than 
 a mere brushing of the pole, they will not prove as effective as 
 though the preservative is driven through the sapwood. In 
 some cases, the surface of the pole has been perforated with small 
 holes in order to facilitate the entrance of the preservative and 
 shorten the time of treatment. 
 11 
 
162 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 Poles to be butt-treated are hoisted by a derrick into open tanks, 
 where they are stood on end. The preservative is then admitted 
 until the butts are submerged. If creosote or a similar oil is used, 
 it is heated to about 215° F. for two or more hours, after which 
 it is permitted to cool, or cool oil is pumped into the tank and the 
 butts kept submerged until the desired absorption is obtained. 
 In a similar manner the poles can be treated with zinc chloride. 
 By running the hot oil out of the tank and admitting a zinc- 
 chloride solution, a combination treatment can be obtained, or 
 the poles can be lifted out of the hot tank and stood in a second 
 tank containing the solution. Table 17 gives some results 
 secured in butt-treating poles by the open-tank method and shows 
 the amount and depth to which the preservative was absorbed.^ 
 
 Table 17. — Average Absorption and Penetration of Creosote 
 tained in the butt treatment of polbs bt the 
 Open-tank Method 
 
 Ob- 
 
 Species 
 
 Absorp- 
 tion per 
 pole 
 
 Pene- 
 tration 
 
 Species 
 
 Absorp- 
 tion per 
 pole 
 
 Pene- 
 tration 
 
 Chestnut 
 
 Pounds 
 21.5 
 
 48.4 
 39.5 
 
 Inches 
 0.3 
 
 0.5 
 0.8 
 
 Western yellow 
 
 Pounds 
 
 81.4 
 34.0 
 
 Inches 
 
 3.1 
 1.0 
 
 Northern white 
 
 cedar 
 
 Western red cedar 
 
 Lodgepole pine 
 
 Entire Impregnation. — If the poles decay in the top as well as 
 in the butt, the entire pole should be treated. This is done by 
 placing them on cylinder cars and running them into a treating 
 cylinder. The treatment is very similar to that given ties, no 
 special apparatus being required except that the cars should be of 
 the bolster type in order to take curves. The best process is the 
 full-cell creosote injecting about 10 poundsl of oil per cubic foot. 
 This method of treatment is most expensive on account of the 
 large amount of creosote absorbed. It should not be used if 
 open-tank treatmeiits will suffice. A modified treatment has been 
 suggested whereby the poles are run into horizontal cylinders 
 mounted on pivot bearings, after which the cylinder is revolved 
 to a vertical position. In this way it is possible to impregnate 
 the butt under pressure and give the top of the pole a lighter 
 treatment, thus saving materially in total cost. So far as known 
 
 1 Bulletin 84, U. S. Forest Service, by Wm. H. Kempfer. 
 
PROLONGING THE LIFE OF POLES 163 
 
 to the author, this method has not been practised thus far, 
 although it has much to commend it. 
 
 Boucherie Process. — In this process, which is extensively used 
 in France and which has been tested in our country, the poles are 
 treated green and before the bark is removed, (See Plate XVI, 
 Fig. A.) In fact, the sooner the treatment can be given after the 
 trees are cut the better the results secured. A clamp is placed over 
 the butt of the pole, which is placed in a horizontal position; 
 through this clamp a hole is bored, into which a wooden plug 
 is inserted. The plug is connected to a hose, which in turn is 
 fastened to a larger hose or pipe. A barrel or other vessel filled 
 with copper sulphate, and elevated about 20 ft. above the pole so 
 as to give a static pressure, is connected by means of a hose to 
 this feed pipe. In this way the copper-sulphate solution runs 
 out of the overhead tank and forces its way into the butt of 
 the pole and eventually through its entire length. As soon as 
 the solution appears at the top end, the pole is disconnected 
 from the treating apparatus, after which it is peeled, trimmed, 
 and air seasoned. It is then ready for use. 
 
 The Boucherie process is very well adapted to the treatment 
 of poles in small quantities and in rough country where there is 
 a supply of timber suitable for poles and where the cost of trans- 
 porting treated poles would be prohibitive. Experiments with 
 this process were made by the U. S. Forest Service in California, 
 the time required to impregnate the various poles being given in 
 Table 18.' The poles were treated green under a pressure of 
 about 10 pounds. Their length was about 22 ft. 
 
 Table 18. — Time Required to Treat Green Poles by the Boucherie 
 
 Process 
 
 Species 
 
 Average time required to impregnate poles 
 
 Yellow pine 
 
 (Days) 
 3.5 
 2.9 
 6.2 
 1.9 
 3.1 
 
 White fir 
 
 Douglas fir 
 
 Incense cedar 
 
 Sugar pine 
 
 Kyan Process. — This process has been used extensively in 
 Europe for treating poles and has given very good results. The 
 
 1 From report by Geo. M. Hunt and C. S. Smith, of the U. S. Forest 
 Service. 
 
164 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 manner in which the process is operated has been described in 
 Chapter V. Next to poles impregnated by the full-cell process, 
 Kyanized poles have given greatest durability. The treatment 
 is comparatively inexpensive when compared with the full-cell 
 creosote and in addition the surface of the poles is clean and 
 free from oily exudations. It is believed the process can be 
 adapted to many conditions in our country and is well worthy 
 of a more extended trial. While no tests which have been made 
 are known by the author, it is probable that a treatment with 
 mercuric chloride can be given poles in much the same manner 
 as they are now treated by the Boucherizing process, although 
 the uniformity of the penetration might not be as good as when 
 the poles are first air seasoned. 
 
 Reenforcing Decayed Poles. — The expense of replacing de- 
 cayed poles with new ones is considerable, as all the wires must 
 be restrung, in addition to replacing the pole proper. For this 
 reason, some companies have attempted to reenforce their de- 
 cayed poles in an effort to prolong their life. Two methods 
 have been rather extensively tried, viz., reenforced stubs and re- 
 enforced jackets. The former consists in placing a stub buried 
 in the ground next to the pole and bolting or wiring the pole to 
 it. (See Plate XVI, Fig. B .) These stubs are often creosoten by 
 the brush or full-cell method. They undoubtedly increase the 
 strength of the decayed pole but their reenforcement is only 
 temporary and final removal is generally deferred for but a com- 
 paratively short period. 
 
 An effective method consists in cutting all decayed wood 
 from the pole for some distance below and above ground. The 
 pole is then brush treated with a preservative like creosote, after 
 which steel reenforcing rods are driven into it and the whole 
 buried in creosote. This method is claimed to give very good 
 results and add materially to the strength and life of the pole. 
 No definite records on the added life thus secured are, however, 
 known to the author, but an estimated life of 8 to 10 years is 
 claimed. The cost of such a treatment is about $3.50 to $5 per 
 pole. (See Plate XVI, Fig. C.) 
 
 In some cases, after a pole has decayed, it is cut off at the 
 ground line, the decayed butt removed, and the pole lowered 
 in the same hole. This practice is common and feasible when 
 the length of the pole is suf&cient to stand this shortenihg. It 
 }s believed that better results would be secured if the sound por- 
 
Plate XVI 
 
 Fig. a. — A Boucherie pole treating plant, Pulda, Germany. (Forest Serv- 
 ice photo.) 
 
 ^L 
 
 Q 
 
 ^ 
 
 
 
 
 1 
 
 1 
 
 u 
 
 * 
 
 HI*""" 
 
 
 ^^^^Hio^^l^^^^^^B^- ^ 
 
 ^^^S^TSm 
 
 JM 
 
 B| 
 
 
 
 H 
 
 pi 
 
 ■u 
 
 m 
 
 ^fev '■ 
 
 1 
 
 H 
 
 m 
 
 
 
 
 1 
 
 1 
 
 1 
 
 1 
 
 
 ■ 
 
 1 
 
 V .1 ^ 41 
 
 ■ 
 
 Fig. B. — Partially decayed pole reenforced with a creosoted stub. (Forest 
 
 Service photo.) 
 
 (Facing page 164.) 
 
Plate XVI 
 
PROLONGING THE LIFE OF POLES 
 
 165 
 
 tion of the pole was given two coats of hot creosote before it was 
 lowered into the ground. As the ground about the hole is in- 
 fected with decay-producing fungi, the life of a pole set in such soil 
 will not be as great as the life of a pole set in a freshly dug hole. 
 
 Cost of Treatment. — ^The cost of treating poles varies through 
 wide limits. It depends chiefly upon (1) the process used, (2) 
 the size of the pole, (3) the cost of the preservative, (4) the cost of 
 labor, and (5) the number of poles treated per day. In order to 
 have some general data, however. Table 19 has been compiled, 
 but in using it the reader is cautioned against drawing too sharp 
 conclusions. Creosote is assumed to cost 1 cent per pound, 
 labor 12 per day, the size of pole to be 30 feet, and the treatments 
 given as already described. 
 
 Table 19. — Estimated Cost of Treating Poles 
 
 Kind of treatment 
 
 Amt. of preserva- 
 tive used per pole 
 (pounds) 
 
 Cost per pole 
 
 Field or crushed stone around pole 
 
 
 $0.00-80.20 
 0.05- 0.15 
 0.15- 0.30 
 1.00- 1.50 
 1.70- 2.25 
 
 Charring butt 
 
 
 Brush treatment (2 coats creosote) 
 
 Open-tank butt treatment creosote 
 
 Entire pole treated — ^full-cell creosote 
 
 8° 
 
 50" 
 
 144" 
 
 " = about 24 square feet surface. 
 ' = about 6 cubic feet treated. 
 " = about 18 cubic feet treated. 
 
 A more detailed estimate of the cost of butt-treating poles, 
 based on an open-tank plant having a daily capacity of 120 poles 
 per day or 30,000 per year (250 working days), is as follows:' 
 
 Labor per Day 
 
 1 yard foreman $4 . 00 
 
 1 plant engineer 4 . 00 
 
 1 stationary engineer 4 . 00 
 
 2 firemen, at 12.50 5.00 
 
 5 laborers, at $2 10.00 
 
 Total • $27.00 
 
 Labor charge per pole $0 . 225 
 
 Fuel per Day 
 
 2 tons coal, at $4 18.00 
 
 Fuel charge per pole . 067 
 
 'Bulletin 84, U. S. Forest Service. 
 
166 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 Maintenance pee Ybae 
 
 Depreciation and repairs 1600 . 00 
 
 Interest on investment in plant and preservatives 400 . 00 
 
 Total S900.00 
 
 Maintenance charge for pole $0 . 030 
 
 Seasoning charge per pole (interest on investment) . 100 
 
 Total treating charge, exclasive of preservative $0,422 
 
 The cost of treatment, exclusive of preservative, based on a 
 liberal estimate for all charges, is thus seen to be $0,422 per pole. 
 To this should be added the cost of the preservative, taxes on 
 property, and, if the treating plant is not located at a central 
 seasoning or distributing yard, extra shipping charges. 
 
 Economy of Treatment. — Treated poles have not been in use 
 in this country for a sufficient period to furnish actual data on 
 the length of time their life has been prolonged. In Germany, 
 where fairly accurate information is at hand, the following results 
 have been secured based on about 50 years experience: 
 
 Untreated poles 7.7 years average life 
 
 Poles treated with copper sulphate 11.7 years average life 
 
 Poles treated with zinc chloride 11.9 years average life 
 
 Poles treated with mercuric chloride 13.7 years average life 
 
 Poles treated with creosote 20 . 6 years average life 
 
 The amount of creosote injected in each case, and the exact con- 
 ditions under which the poles were set, are not known. We have 
 records in this country, however, of longleaf pine poles treated 
 by the full-cell creosote process and set in Virginia which are 
 perfectly sound after 18 years' service. Accurate records on 
 the durability of poles in the United States, so far as these are at 
 present obtainable, are given in Fig. 31 and Fig 32, appendix. 
 Using them and the cost of treatments given above, the econ- 
 omy of treatment can be approximated as in Table 20. 
 
 It will be noted from the estimates given in the table that poles 
 butt-treated with creosote by the open-tank method are the 
 cheapest to maintain. In this connection, however, several 
 factors should be kept clearly in mind. It has been assumed in 
 the table that the tops of the poles do not decay. While this 
 condition is true for a large part of our country, it must not be 
 universally applied. If the top is subject to decay, the full-cell 
 creosote process will undoubtedly be found to give lowest main- 
 
PROLONGING THE LIFE OF POLES 
 
 167 
 
 tenance charges, although its initial cost of installation will re- 
 main highest. Another very important point is the kind of wood 
 used in the pole. Northern white cedar has been selected in the 
 table because of its uniform excellence and very extended use. 
 If other varieties are employed the annual charges shown in 
 the table will, of course, be materially changed. For example, 
 a loblolly pine pole will last untreated about 4 years, whereas the 
 northern white cedar is estimated at 14 years. When given a 
 butt or full-cell treatment with creosote, the difference in the 
 annual charges between treated and untreated loblolly pine poles 
 will be much greater than the differences between treated and 
 untreated cedar poles, because of the natural durability of the 
 latter. Consequently, poles possessing less natural durabiUty 
 will, when treated, show greater economy in treatment than poles 
 possessing great natural durability. Furthermore, the lower 
 price at which such poles can generally be secured will frequently 
 make their use, when properly treated, cheaper than the more 
 naturally durable poles. The wide range through which these 
 conditions vary frustrates any attempt to arrange them in a 
 table that would be of practical value, hence no attempt to do so 
 has been made. 
 
 Table 20. — Estimated Annual Charges op Cedar Poles Treated by 
 
 Various Methods 
 
 Method of Treatment 
 
 Coat of 
 treatment 
 
 Coat of 
 
 pole aet in 
 
 line 
 
 Eatimated 
 Ufe 
 
 Annual 
 charge 
 
 $ 
 
 Untreated 
 
 Charred at butt 
 
 Butt brush-treated 
 
 Boucherie 
 
 Butt treated zinc chloride 
 
 tank) 
 
 Butt treated mercuric chloride 
 
 (open tank) 
 
 Butt treated creosote (ope'x tank). 
 Full-cell creosote (pressure; 
 
 (open 
 
 0.15 
 0.25 
 0.70 
 
 0.60 
 
 0.90 
 1.25 
 2.29 
 
 7.00 
 7.15 
 7.25 
 7.70 
 
 7.60 
 
 7.90 
 
 8.351 
 
 9.50' 
 
 Years 
 14 
 15 
 18 
 20 
 
 22 
 
 24 
 30 
 30 
 
 0.71 
 0.69 
 0.62 
 0.62 
 
 0.58 
 
 0.59 
 0.54 
 0.62 
 
 Pole — northern white cedar. 
 Life — untreated = 14 years. 
 Cost of pole =-$4. 
 
 Cost of placement = $3. 
 Size of pole = 30 feet. 
 Interest 5 percent compounded an- 
 nually. 
 
 ' Extra charge for increased weight due to treatment. 
 
168 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 CROSS ARMS 
 
 Selection of Species. — Two kinds of wood, Douglas fir and 
 pine (mostly longleaf), furnish about 90 percent of the 3,500,000 
 cross arms used annually in the United States. Other varieties 
 such as oak, cypress, spruce, junipe;;, cedar, chestnut, and locust 
 are also used, but in scatterng quantities. Due to the manner 
 in which they are placed, decay in cross arms is not jiearly as 
 serious as decay in poles. The problem of selecting material 
 for cross arms is therefore largely confined to those species which 
 occur in sufiicient quantities in one locality and thus warrant the 
 installation of the special machinery necessary to manufacture 
 cross arms at low cost. Douglas fir and longleaf pine are the 
 woods now most largely manufactured into lumber and occur 
 in enormous stands over a wide area. The intrinsic properties 
 desired in a cross arm are strength, freedom from warping and 
 checking, a comparatively light weight, and resistance to decay. 
 Even when the arms are to be treated, their ability to absorb the 
 preservative is not of prime importance, as only small quantities 
 of an efficient preservative are necessary in order to protect them 
 from decay. For greatest strength at least weight, redwood is 
 one of the best cross-arm materials used and it is surprising that 
 more redwood arms are not in service. A distinction is made 
 between arms cut from Douglas fir, the trade recognizing two 
 distinct types known as "yellow" and "red" fir. The former 
 is claimed to be the better arm and far more durable than the 
 latter, cases being on record where such arms untreated were in 
 service over 40 years without any signs of decay. It is probable, 
 however, that this long service was due to the comparatively 
 dry climate (Utah) in which these arms were used. 
 
 The Manufacture of Cross Arms. — It is quite essential that 
 the wood from which cross arms are made be of straight grain 
 free from defects such as knots, spiral grain, checks, etc., which 
 tend to decrease their strength. This is especially true for that 
 portion of the arm at and near the middle, as failure is most 
 likely to occur at this portion. 
 
 It is also important to have the arm brought to exact dimen- 
 sions and all holes bored before any preservative treatment is 
 given. 
 
 Methods of Seasoning. — On account of their comparatively 
 small size and the ease with which they can be handled, cross 
 
PROLONGING THE LIFE OF POLES 
 
 169 
 
 arms are generally air seasoned before they are shipped or treated. 
 The usual precautions for the condition of the seasoning yard, as 
 described in Chapter VIII, hold as well for cross arms. Many 
 forms of piles have been tried but those which give best satisfaction 
 are open piles without roofs, in which the end arms in each tier 
 are placed with their depth vertical while the arms in between 
 are placed with their depth horizontal. (See Plate XVII, Fig. A.) 
 This allows a free circulation of air and induces rapid drying. 
 
 From a large number of measurements, the shrinkage in con- 
 iferous cross arms from a green to air-dry condition is of little or 
 no practical significance. The same holds for any changes in the 
 shape of the holes bored into the arms. In hardwood cross arms 
 these changes are much greater. 
 
 Cross arms season rapidly and reach an air-dry condition in 
 about 1 month. In summer this rate may even be exceeded, 
 while in winter or rainy weather longer periods are of course 
 necessary. Some experiments were made by the U. S. Forest 
 Service in air-seasoning loblolly pine arms, which, according to 
 the amount of sap wood they contained, were divided in three 
 charges, heartwood, sapwood, and intermediate. The manner 
 in which these arms seasoned is shown in Table 21.^ 
 
 Table 21. — Comparative Rates op Seasoning op Loblolly Pine 
 Heartwood, Sapwood, and Intermediate Cross Arms 
 
 Days 
 seasoned 
 
 Heartwood 
 
 Sapwood 
 
 Intermediate ] 
 
 Weight 
 per arm 
 
 Weight 
 per cu- 
 bic foot 
 
 Mois- 
 ture 
 content 
 
 Weight 
 per 
 arm 
 
 Weight 
 per cu- 
 bic foot 
 
 Mois- 
 ture 
 content 
 
 Weight 
 per 
 arm 
 
 Weight 
 per cu- 
 bic foot 
 
 Mois- 
 ture 
 content 
 
 
 
 Pounds 
 38.8 
 34.2 
 33.9 
 34.3 
 34.2 
 33.9 
 33.6 
 
 Pounds 
 42.6 
 37.6 
 37.3 
 37.3 
 37.6 
 37.3 
 36.9 
 
 Percent 
 51.5 
 33.4 
 32.5 
 33.8 
 33.7 
 32.3 
 31.2 
 
 Pounds 
 52.7 
 34.5 
 32.6 
 32.6 
 32.5 
 32.1 
 31.6 
 
 Pounds 
 57.9 
 37.9 
 35.8 
 35.8 
 35.7 
 35.3 
 34.7 
 
 Percent 
 105.8 
 23.8 
 27.2 
 27.3 
 26.9 
 24.5 
 23.6 
 
 Pounds 
 45.8 
 34.8 
 33.3 
 33.4 
 33.4 
 33.0 
 32.5 
 
 Pounds 
 50.3 
 37.7 
 36.6 
 36.7 
 36.7 
 36.3 
 35.7 
 
 Percent 
 79.0 
 34.0 
 30.0 
 30.3 
 30.3 
 29.0 
 26.9 
 
 30 
 
 60 
 
 90 
 
 120 
 
 150 
 
 180 
 
 Methods of Treatment and Their Selection. — As above stated, 
 cross arms are not subject to severe attack by fungi, since they are 
 surrounded on all sides by air and are raised a considerable dis- 
 tance above ground. Decay is most likely to occur at the bolt 
 and pin holes. It is quite essential, therefore, to have these prop- 
 erly protected. If the arm is of a naturally durable wood such as 
 white or red cedar, heart cypress, etc., no preservative treatment 
 
 ^ Circular 151, U. S. Forest Service. 
 
170 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 is necessary, as the arm will unquestionably last much longer than 
 the pole. If, however, the wood is not so durable, such as pine, 
 fir, spruce, etc., a preservative treatment is desirable. 
 
 If the preservative selected is a salt, such as zinc or mercuric 
 chloride, objections can be raised in that it will tend to wash from 
 the wood, it will attack the iron spikes or bolts, and it will tend 
 to keep the arms more or less moist thus lowering the strength 
 of the arms and decreasing their resistance to the leakage of 
 electric current. 
 
 On the other hand, if creosote is used, it will tend to volatilize 
 quickly from the arms, or if large quantities are injected danger 
 from drip may be encountered. Cases are on record where com- 
 panies have been forced to replace their arms because of the dam- 
 age done by such dripping. Arms heavily creosoted are, more- 
 over, increased perceptibly in weight. 
 
 Taking all these factors into consideration, it is believed that 
 arms treated with about 5 to 6 pounds of creosote per cubic foot 
 by an empty-cell process so that no drip will occur will give 
 best results. In doing this, however, it is important to use a 
 high-grade preservative, so that loss from volatilization can be 
 kept to a minimum. 
 
 Dipping the arms in a tank of hot preservative such as coal- 
 tar creosote or carbolineum for several minutes should also give 
 good results. The oil will run into all checks and holes and, as 
 wood is most easily treated in the direction of the grain (longi- 
 tudinally), a good penetration will be secured at those points 
 which require greatest protection. 
 
 Kyanized arms are reported to have given excellent service. 
 The process produces clean arms and adds practically no dead 
 weight. 
 
 Cost of Treatment. — ^The cost of treating cross arms is very 
 variable. When large quantities are handled and apparatus is 
 at hand for doing the work mechanically, the cost is kept at a 
 minimum. It has been assumed in the estimates given in Table 
 22 that these mechanical features have been provided. 
 
 Table 22. — ^Approximate Cost of Treating Cross Arms 
 
 Process used 
 
 Total cost per arm (10-pin) (cents) 
 
 Full-cell creosote 
 
 10-20 
 7-10 
 4- 8 
 
 10-30 
 
 Empty-cell creosote 
 
 
 Dipping carbolineum '. 
 
Plate XVII 
 
 Fig. a. — Cross arms properly piled for air seasoning. (Forest Service 
 
 photo.) 
 
 PiQ B — Creosoted cross arms just leaving the treating cylinder, Norfolk 
 Greosoting Co. (Forest Service photo.) 
 
 (Facing page 170.) 
 
Plate XVII 
 
 Fig. C. — Fence posts properly piled for air seasoning. (Forest Service 
 
 photo.) 
 
 Fig. D. — Untreated lodgepole pine post set four years. Note decay at the 
 ground. (Forest Service photo.) 
 
PROLONGING THE LIFE OF POLES 
 
 in 
 
 Economy of Treatment. — Only estimates based upon the opin- 
 ions of operators and our knowledge of the decay of wood can be 
 given in arriving at the probable economy resulting from the pre- 
 servative treatment of arms. No authenticated records are 
 known to the author of the service secured from treated arms in 
 actual use. It is only reasonable to expect that climatic condi- 
 tions will affect very materially the life of cross arms. For ex- 
 ample, arms in the South where the air is often warm and moist 
 will tend to decay much more rapidly than arms in dry or cold 
 climates. In fact, it is doubtful whether the treatment of arms, 
 other than a mere soaking in the preservative of the bolt and pin 
 holes and the center portion in contact with the pole, under these 
 latter conditions is at all feasible or necessary. As has been 
 stated, cases are on record of yellow fir arms which in a com- 
 paratively dry climate like Utah and Nevada lasted untreated 
 for over 40 years without any signs of decay. Of course, such 
 conditions cannot be expected for the greater part of our country, 
 so that a treatment of some sort is generally advisable. 
 
 The estimates given in Table 23 are very rough as no data 
 could be found giving the lives of cross arms treated in the 
 manner suggested. 
 
 Table 23. — Estimated Annual Saving Due to Treatment of Ckoss 
 Arms (Interest Compounded at 5 Percent) 
 
 Item 
 
 Fir I Pine 
 
 Life untreated (years) 
 
 Life treated by empty-cell process (years) 
 
 Life treated by dipping process in creosote (years) .... 
 Life treated by dipping process in carbolineum (years) 
 
 Cost untreated in place (dollars) 
 
 Cost treated by empty-cell process in (place) 
 
 Cost treated by dipping process using creosote 
 
 Cost treated by dipping process using carbolineum . . . 
 
 Annual charges untreated 
 
 Annual charges treated by empty-cell process ........ 
 
 Annual charges treated by dipping process (creosote) . 
 Annual charges treated by dipping process (carbolineum) 
 
 15.0 
 
 10.0 
 
 25.0 
 
 30.0 
 
 20.0 
 
 18.0 
 
 21.0 
 
 19.0 
 
 1.50 
 
 1.50 
 
 1.58 
 
 1.58 
 
 1.56 
 
 1.56 
 
 1.60 
 
 1.60 
 
 0.150 
 
 0.190 
 
 0.110 
 
 0.100 
 
 0.125 
 
 0.130 
 
 0.125 
 
 0.130 
 
CHAPTER X 
 
 PROLONGING THE LIFE OF FENCE POSTS FROM 
 DECAY 
 
 Selection of Species. — Where trees abound, fence posts are 
 generally made from timber easiest to cut. For this reason 
 practically all kinds of wood large enough to make a post are used 
 and a list of them would comprise nearly all species which grow 
 in our country. Where post timber is scarce, greater care is 
 taken in selecting the kinds of wood cut into posts, and in any 
 event the durable species are almost invariably the best ones to 
 use. Aside from the question of cost, which is always of first 
 importance, the qualities demanded of a good post wood are 
 durability, form, and ability to hold staples or nails. If the posts 
 are to be given a preservative treatment, their ability to take 
 treatment must also be considered. 
 
 The durability of posts is very variable even when cut from the 
 same kind of wood, so that any estimates on durability must be 
 judged with considerable latitude. Posts set in wet ground are 
 more durable than posts set in soil alternating wet and dry. 
 Posts cut from slow-grown trees are generally more durable than 
 posts cut from rapid-grown trees. To these variations must be 
 added the variations due to climatic conditions. 
 
 The best formed posts come usually from the coniferous trees 
 like cedar, pine, fir, etc., and fences set with them have the neat- 
 est appearance. Crooked posts are more liable to pull the 
 staples, as the wires fastened to them are not in alignment. 
 
 In general, the staple or nail-holding power of a post varies 
 with its dry weight. That is, posts cut from heavy woods like 
 locust, oak, etc., will hold staples better than posts cut from light 
 woods like pine and cedar. 
 
 If the posts are to be set untreated, the more heartwood they 
 contain the better. Consequently, split posts are generally 
 more durable than round posts. If, however, a preservative 
 treatment is to be given, round posts are preferable, as the sap- 
 
 172 
 
PROLONGING THE LIFE OF FENCE POSTS 173 
 
 wood can be more easily impregnated than the heartwood and 
 a continuous layer of preserved wood will then extend continu- 
 ally around the post. 
 
 Method and Time of Cutting Posts. — As just mentioned, 
 split posts containing mostly heartwood are preferable to round 
 posts if they are to be set untreated. So far as possible, the ends of 
 the posts should be cut with an axe or fine saw, especially if the 
 posts are of soft wood. A smooth cut enables rain water to run 
 off more freely and is less liable to cause top decay. A slight 
 bevel to the top of the post is also desirable and should be given. 
 If, however, the posts are subject to "frost heave, " that is, 
 thrown out of alignment by frost, the bottoms should be pointed 
 so they can be reset upright in the spring and driven into the 
 ground with a mallet. With such posts, too great a bevel to 
 the top should be avoided. 
 
 It is generally conceded that the best time of the year to cut 
 posts is in winter or late fall, as they are at such seasons less 
 subject to immediate attack byfungi. Furthermore, sprouts from 
 winter-cut stumps are far more vigorous than sprouts from stumps 
 cut in spring or summer. In fact, the sprouting capacity of a 
 stump may sometimes be killed by summer cutting. 
 
 In all cases, whether treated or untreated, posts should be 
 peeled, as the bark offers practically no protection and generally 
 does a positive harm. All bark should be thoroughly removed 
 from that portion of the post to be treated with the preservative 
 so that the preservative can have an opportunity to penetrate 
 uniformly into the wood. 
 
 Method of Seasoning. — Whether or not it pays to season posts 
 which are to be set untreated is still an open question. It 
 appears, however, that the seasoning adds but little to the life 
 of the posts and if it entails much delay or expense is not 
 warranted. 
 
 Of course, where a preservative treatment is to be given, 
 seasoning is as a rule highly advisable, as better penetrations are 
 secured and the protective coating is less subject to injury due to 
 subsequent checking. A simple and effective means of season- 
 ing posts is to pile them in horizontal layers, allowing sufficient 
 space between each post so that air can circulate about them. 
 (See Plate XVII, Fig. C .) If the posts are liable to check seriously, 
 as in the case of the gums and oaks, it is best to pile them 
 closer together and in a shady place. One or two months are 
 
174 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 generally required to produce an air-dry condition but in warm 
 weather two weeks may be sufficient. 
 
 Methods of Treatment and Their Selection. — Farmers are the 
 largest consumers of posts, and most of them make their own posts. 
 The chief requirement for a preservative treatment is, therefore, 
 that it shall be one which the farmer can give himself. In some 
 localities where the posts are bought, a rather elaborate treat- 
 ment can be given and the posts sold in a treated condition. For 
 the most part, however, the most practical methods are those 
 which are simple of execution. The ones most commonly used 
 are described below. 
 
 Setting Posts in Stones. — If stones are abundant, this method is 
 better than setting the posts directly into the soil. If the stones 
 must be hauled long distances, the method will not pay, as it 
 does not materially increase the life of the posts. Its chief ad- 
 vantage lies in that it keeps weeds and vegetation away from 
 the base of the post, thus prolonging its life and protecting the 
 post from ground fires. 
 
 Setting Posts Upside Down. — This is done on the theory that 
 rain-water will run out of the post more readily in this position 
 than when set large end down. There is no evidence whatever 
 to substantiate this and were it not for the widespread belief 
 in this method it would not even be commented upon here. 
 An obvious objection to this method is that it places the small 
 end of the post in the ground and hence gives a weaker post 
 than if set the other way, since greater strength and resistance 
 are required in the butt than in the top. 
 
 Charring the Butt. — Charring at best is a poor method of 
 treatment, since its effect is but slight. If the posts are charred 
 they should first be air seasoned thoroughly and charred from the 
 butt to about 6 inches above the ground line. The charr should 
 not extend more than 1/4 inch into the post. While this treat- 
 ment will tend to increase the durability of the post, it also 
 weakens it at the very point where it needs greatest strength. 
 However, if the charring can be done at slight expense, it will 
 more than pay for itself through added durabiUty. 
 
 Dipping in Crude Oil and Charring. — If the butt ends of the 
 posts are dipped for a few minutes in crude oil and then charred 
 better results than simple charring are obtained. (See Plate 
 XVIII, Fig. A.) This method is, however, also subject to criti- 
 cism in that it weakens the posts at the butt. It seems that 
 
PROLONGING THE LIFE OF FENCE POSTS 175 
 
 burning the posts after their oil treatment tends to drive some of 
 the hot oil into the wood. Some experiments made along this 
 line by the Wyoming Experiment Station showed pitch-pine 
 posts to be sound after 16 years of service. It should be stated, 
 however, that these posts set untreated under similar con- 
 ditions would last at least 12 years, so that the efficacy of the 
 treatment is not pronounced. 
 
 Diagonal Holes Filled with Preservative. — This method of 
 treatment consists in boring 2 or 3 holes about 1/2 inch in 
 diameter and 3 inches deep diagonally downward into the post 
 near the ground line, and pouring a preservative such as a solu- 
 tion of copper sulphate, mercuric chloride, kerosene, etc., into the 
 hole, after which it is plugged. When the preservative escapes 
 from the cavity, the plug is removed and more inserted. This 
 treatment is not recommended, first because it weakens the post, 
 second because the preservative does not diffuse evenly through 
 the post as claimed, and third because the results secured are not 
 sufficient to pay for the trouble and expense of the treatment. 
 
 Brush Treatments. — If posts are first air seasoned and then 
 given two coats of a good preservative like coal-tar creosote or 
 carbolineum in the manner described in Chapter V, their natural 
 life can be increased from 3 to 6 years. The entire butt of the 
 post should be treated to a distance about 1 foot above the 
 ground line. The preservative had best be applied hot and worked 
 into the cracks "as completely as possible. Brush treatments 
 when properly applied will more than pay for themselves but are 
 not as efficient as can be given. In the case of posts that decay 
 at the top, such as maple, gum, etc., it is well also to brush-treat 
 the top. 
 
 Dipping Treatments. — These are more effective than brush 
 treatments, as the preservative is sure to run into all checks. 
 As posts can be easily handled, this method is recommended, par- 
 ticularly where only a few posts are to be treated. Creosote or 
 a similar preservative is the best obtainable for dipping treat- 
 ments. All that is necessary is to have the preservative hot 
 (about 150°-180° F.) and dip the butt ends of the post in a tank 
 or barrel containing the oil for about 1/4 minute, after which they 
 can be removed. The post should be submerged to a depth of 
 about 1 foot above the ground line. One dipping will give good 
 results. Better absorptions and penetrations will be secured, 
 however, if the post is dipped twice, a sufficient time elapsing 
 
176 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 between treatments to allow the first to dry. Tar is not recom- 
 mended for either brush or dipping treatments. 
 
 Impregnation Treatments. — Treatments of this kind are the 
 best known, although the most troublesome and expensive to 
 make. If the preservative selected is a salt like zinc or mercuric 
 chloride or copper sulphate, all that is necessary is to stand the 
 air-seasoned posts in a tank or vessel containing a solution of the 
 preservative. For zinc chloride a 6 percent solution is recom- 
 mended, while for copper sulphate 1.5 percent and for mercuric 
 chloride 0.9 percent is sufficient. If the latter salt is used great 
 care should be taken in handling it and keeping it away from ani- 
 mals because of its very poisonous nature. With copper and 
 mercury solutions, wooden or stone vessels or tanks should be 
 used, as they will attack iron. The posts should remain standing 
 in the preservative for about 1 week. 
 
 Better results can be secured with coal-tar creosote, but to get 
 most effective treatments the oil should be heated as described 
 in Chapter V. If but one tank is used, the oil and posts can be 
 heated and then allowed to cool in it. This cuts down the num- 
 ber of posts that can be treated per day and is called a "single- 
 tank treatment." If two tanks are used, one for hot oil and one 
 for cool oil, quicker results are secured. Such treatments are 
 known as "double-tank treatments." The U. S. Forest Service 
 has made a large number of tests in treating posts by these meth- 
 ods and has obtained some very satisfactory results. These are 
 shown in Table 24. 
 
 The treating tanks necessary to treat posts in this manner 
 and the method of operating them are described in Chapter V 
 (open-tank process). 
 
 While no tests that have been made are known to the author, 
 it is believed that if the posts are boiled in crude oil or any cheap 
 oil for 2 or 3 hours and then quickly plunged into a tank 
 containing a solution of zinc chloride, copper sulphate, or mer- 
 curic chloride at atmospheric temperature, as described above, 
 and left standing in this solution for 3 or 4 hours, very 
 good results will be secured and at a lower cost than if only coal- 
 tar creosote were used. It is quite likely that green posts can 
 be treated in this manner and good penetrations obtained, but 
 in such cases the length of the boiling period will probably have 
 to be increased somewhat. In no case should the posts be heated 
 above 275° F. 
 
PROLONGING THE LIFE OF FENCE POSTS 
 
 177 
 
 Table 24. — Best Results Sectjbbd in the Treatment of Various 
 
 WOODS^ 
 
 ( 
 
 All posts 
 
 were round, peeled, and seasoned) 
 
 
 
 Species 
 
 Absorp- 
 tion creo- 
 sote per 
 5-inch 
 post 
 
 Penetration 
 
 Single-tank treatment 
 
 Double-tank 
 treatment 
 
 2 feet 
 from 
 butt 
 
 2 feet 
 from 
 top 
 
 Butt 
 
 Top 
 
 Hot 
 oil 
 
 Cold 
 oil 
 
 Hot 
 
 oil 
 
 Cool- 
 ing oil 
 
 
 Gal. 
 0.4 
 0.6 
 0.6 
 0.6 
 0.4 
 f 0.4 
 \ 0.6 
 0.6 
 0.4 
 0.6 
 0.6 
 0.6 
 0.4 
 0.6 
 0.6 
 0.6 
 0.5 
 0.4 
 0.5 
 0.6 
 0.5 
 0.5 
 0.5 
 O.S 
 0.6 
 0.6 
 0.6 
 
 In. 
 
 0.4 
 
 0.1 
 
 1.0 
 
 0.7 
 
 0.56 
 
 0.6 
 
 0.3 
 
 0.3& 
 
 0.46 
 
 0.6 
 
 0.6 
 
 1.0 
 
 0.5 
 
 0.4 
 
 1.0 
 
 0.2 
 
 1.06 
 
 0.5 
 
 1.5 
 
 1.2 
 
 1.0 
 
 1.0 
 
 1.0 
 
 0.5 
 
 1.0 
 
 0.4 
 
 0.6 
 
 In. 
 
 0.05 
 
 0.4 
 
 0.3 
 
 0.1 
 0.1 
 
 0.3 
 0.3 
 0.3 
 
 0.2 
 0.3 
 0.1 
 0.5 
 0.3 
 1.0 
 0.6 
 0.3 
 0.4 
 0.3 
 0.2 
 0.2 
 0.1 
 0.2 
 
 Hr. 
 5 
 
 Hr. 
 
 12 
 
 Dipped" . . 
 
 Hr. 
 
 Hr. 
 
 Basswood 
 
 Beech 
 
 Birch, river 
 
 
 1 
 1 
 3 
 
 i 
 1 
 
 
 
 
 
 
 
 6 
 
 }■ 
 
 12 
 12 
 
 
 Cottonwood 
 
 Dipped".. 
 
 /■• 
 
 
 li 
 
 1 
 
 u 
 
 Elm, slippery 
 
 Elm, white 
 
 6 
 
 12 
 
 
 
 
 1 
 
 1 
 1 
 
 1 
 
 1 
 
 Gum, cotton (tupelo) . 
 
 Gum, sweet (red) 
 
 Hickory, bitternut. . . . 
 Magnolia, sweet (bay) 
 
 
 
 
 
 
 
 6 
 
 12 
 
 Dipped" . 
 
 
 1 
 4 
 3 
 1 
 1 
 li 
 
 u 
 
 3 
 3 
 3 
 6 
 1 
 2 
 4 
 
 i 
 
 2 
 
 2 
 i 
 J 
 
 1 
 1 
 1 
 2 
 1 
 12 
 i 
 
 i 
 
 1 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 Pine, lodgepole 
 
 
 
 
 
 
 
 
 
 
 
 Pine, shortleaf 
 
 Poplar, white 
 
 
 
 
 
 
 
 
 
 
 Tulip-tree 
 
 
 
 
 Willow, white' 
 
 
 
 
 " Dipped for 6 minutes or more. 
 
 ^ Width of sapwood. Penetration limited by impenetrable heart. 
 
 " Requires especially thorough seasoning. 
 
 Pitch Streaks. — It is well known that pine posts which contain 
 large amounts of resin are more durable than pine posts which are 
 not resinous. This fact is taken advantage of in certain portions 
 of the South by peeling all of the bark off a small tree to a height 
 of 7 or 8 feet except for a strip about 2 inches wide, which is 
 sufficient to keep the tree alive for several years. The tree 
 thus injured covers its wound with resin, which frequently 
 penetrates into the wood for a half inch or more and thus 
 forms pitchy wood. In two or more years the tree is felled and 
 the post cut from it. This method is not recommended, as it 
 is very destructive to timber and wasteful, and the posts are 
 
 'Farmers' Bulletin 387, U. S. Department of Agriculture. 
 
 12 
 
178 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 very liable to catch on fire, if ground fires are common, because 
 of the pitchiness of the wood. 
 
 Cost of Treatment. — Costs of treatment will be estimated 
 only for brush, dipping, and impregnation treatments, as the 
 other treatments described cost practically nothing except for 
 labor, which is generally supplied by the farmer himself at odd 
 times. If labor is included, the cost of the treatments will, of 
 course, depend upon the number of posts which can be treated 
 per day and the value the farmer puts upon his labor. In the 
 following calculations it is assumed that the apparatus used is 
 such as is described in Chapter V and that the price paid for the 
 chemicals is average for small quantities., viz., creosote 2 cents 
 per pound, zinc chloride 5 cents per pound, copper sulphate 
 6 cents per pound, and mercuric chloride 70 cents per pound; 
 these being used in the manner specified above. The total cost 
 of treatments per post (6-inch top 7 feet long) will then be 
 about as estimated in Table 25. 
 
 Table 25. — Estimated Cost of Treating Fence Posts (Butt Only) 
 
 Method of treatment 
 
 Total cost per 
 post (cents) 
 
 Brush-treated coal-tar creosote 
 
 4r-6 
 
 5-7 
 
 3-7 
 12-20 
 
 Dipped coal-tar creosote . ,. 
 
 Impregnated with ziac chloride, copper sulphate or 
 mercuric chloride 
 
 Impregnated with coal-tar creosote 
 
 If the entire post is treated the above costs wiU be about doubled. 
 
 Economy of Treatment. — -As the preservative treatment of 
 fence posts cut from durable wood is unnecessary, it will be 
 assumed that only posts having a comparatively short natural 
 life will be given a treatment. In order to approximate the value 
 of the treatments, therefore, we will take as an example posts 
 cut from such woods as red oak, maple, pine, etc., which decay 
 in about 5 years and which are worth about 5 cents each. The 
 cost of setting the posts will be estimated at 12 cents each. With 
 these assumptions and figuring interest compounded at 6 percent, 
 the annual cost of posts treated by the various methods will be 
 as shown in Table 26. 
 
 It will be noted that, if the values given in the table are approxi- 
 mately correct, the economy resulting from the treatment of 
 posts is not great. The selection of woods to be cut into posts 
 is perhaps of as great or even greater importance. For this 
 
PROLONGING THE LIFE OF FENCE POSTS 
 
 179 
 
 Table 26. — Estimated Annual Chakges of Treated Posts (Butt 
 Treated Only) 
 
 Method of treatment 
 
 Life of 
 
 post 
 (years) 
 
 Cost of post 
 
 set in position 
 
 (cents) 
 
 Annual 
 charges 
 (cents) 
 
 Untreated 
 
 5 
 
 9 
 
 11 
 
 12 
 21 
 
 17 
 22 
 23 
 
 22 
 33 
 
 4.0 
 
 3.2 
 2.9 
 
 2.6 
 
 2.8 
 
 Brush, treated coal-tar creosote 
 
 Dipped coal-tar creosote 
 
 Impregnated with ziac chloride, copper 
 
 sulphate, or mercuric chloride 
 
 Impregnated with coal-tar creosote 
 
 reason, Table 27 is given to show what can be expected from 
 posts cut from a variety of woods. Fortunately, some reliable 
 data from actual experience is available on the life of untreated 
 posts, this data being compiled from painstaking inquiries and 
 researches by Mr. J. J. Crumby of the Ohio Agricultural Ex- 
 periment Station and published by him as Bulletin No. 219 of 
 that station. He examined 292 fences containing 30,160 posts 
 in Ohio, Indiana, Illinois, Kansas, and Texas. The results are 
 shown in Table 27. 
 
 Table 27.— Life of Fence Posts Set Unprotected 
 
 Kind of wood 
 
 Average age 
 
 Percent of 
 
 of fences 
 
 sound posts at 
 
 (years) 
 
 this age 
 
 33.2 
 
 99 
 
 25.4 
 
 82.3 
 
 33.2 
 
 65.3 
 
 23.8 
 
 74.1 
 
 18.4 
 
 68 
 
 17.5 
 
 61.8 
 
 12.3 
 
 71.8 
 
 11.8 
 
 65.2 
 
 6.5 
 
 64.2 
 
 Osage orange 
 
 Locust (black) 
 
 Red cedar 
 
 Mulberry 
 
 White cedar 
 
 Catalpa 
 
 Chestnut 
 
 Oak (mostly white). 
 Black ash 
 
 It can be seen at a glance that posts cut from such durable 
 woods as osage orange, black locust, red cedar, etc., will far out- 
 last nondurable posts treated by the best methods known and 
 will be far cheaper to use even if they cost considerably more. 
 
 The following interesting facts on the life of untreated fence 
 posts are brought out by Mr. Crumley's investigation: 
 
 1. "A large post usually lasts longer than a small one of the 
 same wood. 
 
 2. There is no difference which end is put in the ground, except 
 that the sounder or larger end should have the preference. 
 
180 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 3. In stiff clay soil, the posts rot principally just beneath the 
 top of the ground, and in a porous, sandy, or gravelly soil they 
 usually rot from the top of the soil all the way down. 
 
 4. In soil that is full of water all the time, posts will last 
 longer. 
 
 5. Timber that grows rapidly and in the open is not as good as 
 the same variety that grows in the woods. 
 
 6. There is some evidence that it is not a good time to cut posts 
 just as the tree begins to grow in early spring. 
 
 7. The wood at the center of the tree is not as good as that just 
 inside the sapwood. This characteristic is very common with 
 nearly all the varieties of timber examined, especially so with the 
 locust, white cedar, hardy catalpa, and the oaks." 
 
CHAPTER XI 
 
 PROLONGING THE LIFE OF PILING AND BOATS FROM 
 DECAY AND MARINE BORERS 
 
 To satisfactorily treat piling and timber placed in salt water 
 where marine borers abound is exceedingly difficult of accomplish- 
 ment and the problem is quite different from that of protecting 
 timber from decay. As has been pointed out in Chapter II, 
 it matters little what the wood is, for the borers will rapidly 
 perforate it. The hardest woods like oak and eucalyptus are at- 
 tacked by them. The most resistant wood known against these 
 attacks is the greenheart, but even this will eventually succumb. 
 
 Of course piling driven in fresh water or in the ground is not 
 subject to the attack of marine borers. If such piling is kept 
 continuously submerged or buried, no preservative treatment is 
 necessary, as it will last indefinitely. If, however, parts of it 
 project into the air, decay will take place and some preservative 
 treatment is advisable. The methods described under the 
 treatment for poles may be considered in this connection, except 
 of course if the piling is in water or wet soil soluble salts should 
 not be used. 
 
 Selection of Species. — A good pile timber should be straight, 
 strong, susceptible to treatment, and of moderate cost. Any 
 wood which has these properties can be used to advantage. 
 These requirements are admirably filled by our common southern 
 pines, the loblolly, shortleaf, longleaf, and Cuban. On the 
 Pacific Coast, western yellow pine and Douglas fir are available, 
 although the latter is objectionable on account of its resistance 
 to treatment by present known processes. Strange to say, two 
 woods which differ greatly in their mechanical properties are used 
 untreated for piling with apparent good results. These are the 
 palmetto, which is comparatively weak and "spongy," and 
 greenheart, which is exceedingly strong and dense. The re- 
 sistance of the palmetto is supposed to be due to its porous nature 
 and the natural adversion of the teredo to crossing vacant spaces. 
 The greenheart apparently has some peculiarity not at present 
 understood which is unattractive to the marine borers. 
 
 181 
 
182 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 If the piling is to be used in waters where attack by marine 
 borers is known to be very rapid, only those woods which have 
 a wide sap wood (about 2 inches in width) should be used, as more 
 preservative can be forced into them and better results thus 
 secured. Where attack is less severe, it seems that piling with 
 sapwood about 1 inch wide is preferable, as this tends to con- 
 centrate the oil in the outer portion to a greater extent than when 
 the sapwood is wide. In either case it appears that a con- 
 centration (heavy injection) of oil is better than diffusing the 
 same amount of oil more deeply through the wood — a condition 
 quite the reverse of the protection against fungi. 
 
 The Manufacture of Piling. — In making piling which is to be 
 treated there are two essentials which should be strictly adhered 
 to. First, is a complete removal of all bark from that portion 
 of the pile which will project above the mud line. Bark is very 
 resistant to penetration and if thin strips of it are left adhering 
 to the wood the penetration under such strips may be very slight 
 or none at all; consequently, no matter how well the rest of the 
 pile may be treated, attack will begin at these points and extend 
 rapidly to the interior. Many failures have occurred because 
 this simple rule was violated. (See Plate XVIII, Fig. B.) 
 
 The second precaution is to keep the sapwood continuous 
 and not cut into it so as to expose the heartwood at any point 
 which can be reached by the marine borers. Heartwood does not 
 take treatment as well as sapwood, and is always more subject 
 to attack no matter how well the treatment is given. As that 
 portion of the pile which is driven below the mud line is not 
 subject to attack either by decay or marine borers, and hence 
 will last indefinitely, it is believed that much economy in the 
 treatment of piling could be effected by leaving the inner bark 
 adhering to this portion of the pile. In this way, much less 
 oil would be consumed without in any way affecting the life of 
 the pile. 
 
 Methods of Seasoning. — If the pihng can be air seasoned with- 
 out decay, the method followed is the same as that given for air- 
 seasoning poles. Unfortunately, it often happens that this can 
 not be done, particularly in the South where the air is warm and 
 damp and decay is liable to occur before the pile becomes dry. 
 Some plants store their piling in water prior to treatment or leave 
 them on the ground. Both these methods may become ob- 
 jectionable in that they may cause marked differences in the 
 
Plate XVIII 
 
 Fig. a. — Fence posts dipped in crude oil and then charred. Note good 
 condition after 12 years' service. (Photo courtesy of the Wyoming Exp. 
 Station.) 
 
 Fig. B. — Sections of creosoted piling. Note erratic penetrations of creosote. 
 
 (Forest Service photo.) 
 
 (Facing pctge 182.) 
 
Plate XVIII 
 
 Fig. C. — Pile sheathed with zinc entirely destroyed by marine borers, 
 Pensacola, Fla. (Forest Service photo.) 
 
 Fig. D. — Piling protected with cement casings from attack by marine 
 borers, Pensacola, Fla. (Forest Service photo.) 
 
POLONGING THE LIFE OF PILING AND BOATS 183 
 
 water content of the pile, which in turn is liable to result in 
 unequal penetrations. 
 
 When air seasoning is impossible, live steam or oil seasoning 
 can be used. The methods of doing this have been given in 
 Chapter IV. Care should be taken not to use temperatures 
 above 275° F., as injury to the timber is liable to occur. The 
 length of time the wood should be steamed or boiled varies con- 
 siderably, depending upon the size and "greenness" of the 
 wood and the amount of preservative to be injected. In general, 
 it is between 6 and 18 hours, although longer periods are some- 
 times used. 
 
 Methods of Treatment and Their Selection. — Many methods 
 for treating piling have been tried but only a few have been found 
 meritorious. Only those which have been most commonly 
 practised are described. 
 
 Bark Left on the Piles. — Bark resists the attacks of the marine 
 wood borers, but will adhere only a short time, after which it 
 loosens and falls off. If the piles are to be driven untreated, 
 however, the bark should be left on, except for the portion pro- 
 jecting above high-water level. 
 
 Plank Coating. — Strips of wood nailed tightly together around 
 the pile will ward off attack for a short period, but their value is 
 only temporary. 
 
 Nail Coating. — Flat-headed nails resembling upholsterers 
 tacks driven into the pile close together will prolong the life 
 of the pile. It seems that the iron rust formed by the nails is 
 avoided by some of the marine borers, especially the limnoria. 
 The method is, however, expensive and awkward and not 
 recommended. 
 
 Metal Coating. — Sheets of zinc or copper nailed around the 
 pile at those points subject to borer attacks will effectively pro- 
 tect the pile as long as they last. (See Plate XVIII, Fig. C.) 
 Care should be taken, however, to make all joints tight. The 
 coating will corrode in time and is Uable to puncture by floating 
 debris, but this method of treatment is efficacious. 
 
 Burlap Coatings. — These are made by coating the pile where it 
 is subject to attack with various mixtures such as coal-tar, pitch, 
 asphaltum, sand, etc., and wrapping the whole in several layers of 
 burlap. Very good results have been secured from treatment 
 of this kind. 
 
184 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 Cement Casings.' — These are made in two ways, (1) with 
 no space between the casing and the pile, and (2) with an inter- 
 vening space of from 2 to 4 inches. 
 
 The first are manufactured as follows : The bark and knots are 
 removed and the pile driven. A jacket of iron, wood, or sewer 
 pipe is placed around it, and the space between jacket and pile, 
 which is from 2 to 4 inches wide, is filled with hydrauUc cement. 
 (See Plate XVIII, Fig. D.) When this becomes hard, the 
 jacket is removed. Some jackets are so made that they can be 
 applied to the pile without disturbing the superstructure of the 
 wharf, thus making repairs to broken casings easy. 
 
 The second class is composed of cement pipes divided longitu- 
 dinally into two ■ halves, which, when placed together around 
 the pile, are joined by a scarf joint keyed with a wooden plug 
 soaked in hot tar. The intervening space between pile and casing 
 is filled with sand. The chief advantage of this kind of casing 
 is the fact that broken sections can easily be replaced without 
 removing the superstructure of the wharf. These treatments 
 are very efficient. 
 
 Electrolysis. — A canvas bag or curtain is placed around the 
 pile driven in position and an electric current passed through the 
 pile and the surrounding water. This liberates chlorine gas in 
 the salt water and kills the borers in the pile. It is necessary, 
 of course, to apply this treatment from time to time, since it 
 simply kills the borers present in the wood. The treatment is 
 expensive, but performs a peculiar function in being able to pro- 
 tect piles already set in position and undergoing attack. 
 
 Impregnation with Coal-tar Creosote. — For general work, 
 treatments with coal-tar creosote, by either the Bethell or 
 Boiling process (see Chapter V for details of treatment), have 
 given most effective results. It is necessary, however, to inject 
 large quantities of the oil into the wood (18 to 24 pounds per cubic 
 foot) if the piles are subject to severe attack. This greatly 
 increases the cost of the treatment. However, piles properly 
 treated in this manner have been known to last for 30 years, 
 while untreated piles set in similar waters are completely de- 
 stroyed in 5 years. While this method of treatment is the best 
 known, it leaves much to be desired. It is, as has just been 
 stated, very costly. Furthermore, several cases have been called 
 to the author's attention where the piling so treated has not 
 
 1 Circular 128, U. S. Forest Service. 
 
PROLONGING THE LIFE OF PILING AND. BOATS 185 
 
 withstood attack, especially of the limnoria and xylotria, and 
 failed in less than 8 years after it was driven. There is a 
 distinct need for a good preservative which can be used in 
 treating piling set in waters badly infected with marine borers. 
 (See Plate XIX, Figs. A and B.) 
 
 It seems that a more economical method of treatment than 
 is now practised could be devised. As has already been pointed 
 out, that portion of the pile driven below mud line needs no pro- 
 tection, yet in present methods it receives even more oil than 
 the rest. Furthermore, the portion of the pile above high-water 
 mark does not require as heavy injection as that portion in the 
 water. If a plant could be constructed which could be tilted 
 vertically after the piles are run into it, and only a portion of 
 the pile impregnated, it is believed much expense could be saved. 
 Such a plant would also be admirable for butt-treating poles 
 under pressure. 
 
 The selection of the process to be used in treating piles largely de- 
 pends upon local conditions. If the waters are comparatively free 
 from borers, such as in our more northern harbors on the Atlantic 
 Coast, or if the waters are brackish, a comparatively Ught treat- 
 ment with creosote (10 to 14 pounds per cubic foot) is sufficient. 
 If, however, the borers abound as at Gulfport, Miss., and San 
 Francisco, Cal., the heaviest impregnations should be used. 
 Where the piling can be protected from floating d6bris, casings 
 of cement or metal Jas described above are also effective. These 
 can also be placed over piling already driven into position if it is 
 found attack is taking place. Treatments with burlap, soaked 
 as already described, give good results even in waters badly 
 infected. So far as is at present known, heavy impregnations 
 with coal-tar creosote are, when all things are considered, the 
 most effective that can be given, and they are recommended for 
 all places where attack is severe. 
 
 Cost of Treating Piling. — The total cost of .treating piling by 
 the standard full-cell creosote process including the removal of 
 the strips of inner bark or ' ' skin" left after the piles have been 
 
 Table 28. — Estimated Cost op Treating Piling with 
 Creosote. 
 
 Item I Per cubic foot (cents) 
 
 Cost of peeling and handling at plant . 
 
 Cost of preservative 
 
 Cost of treatment 
 
 Total cost of treatment 
 
 1.0-2.5 
 
 16.5 
 
 3.5-0.0 
 
 21.0-25.0 
 
186 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 roughly peeled in the woods is given in Table 28, where oil is 
 figured at 9 cents a gallon of 8.75 pounds, the piles are steam- 
 seasoned, and 16 pounds of oil per cubic foot are injected. 
 
 Economy in Treating Piling. — The cost of treating and driving 
 piling as well asjhe life secured from it are all so variable that 
 general figures are of value only as an illustration. In prepar- 
 ing the general estimates given in Table 29, two conditions 
 are illustrated, case (A) where piling is driven in salt water 
 where attack by marine borers is light, and case (B) where 
 attack is severe. In the former it is assumed that a treatment 
 of 16 pounds of creosote per cubic foot is given, while in the latter 
 22 pounds are injected. The cost of driving the piling including 
 the superstructure bolted to them is taken as $6 per pile, and all 
 piles are assumed to be 40 feet in length and to contain about 
 25 cubic feet each. Variations of at least 100 percent in the 
 estimated annual savings either way can be expected because 
 of the extremely varying conditions under which piling is used. 
 
 Table 29. — Estimated Economy in Treating Piling' 
 
 Item 
 
 Case A 
 
 Case B 
 
 Life of untreated piling — years 
 
 8 
 25 
 
 $8.50 
 $14.75 
 $1.32 
 $1.03 
 $0.29 
 
 3 
 
 18 
 
 $8.50 
 $16.50 
 $3.12 
 $1.40 
 $1.72 
 
 Life of treated piling — ^years 
 
 Cost of untreated piling — driven in place 
 
 Cost of treated piling — driven in place 
 
 Annual charge^untreated piling 
 
 Annual charge — treated piling 
 
 Annual saving — treated over untreated 
 
 The Preservative Treatment of Wooden Boats. — If wooden 
 boats are used in salt water which contains marine borers, they 
 are very subject to attack and unless properly protected their 
 bottoms may be entirely destroyed in a year or less. For light 
 boats which can be readily hauled out of the water, repeated 
 coatings with copper paint will prove effective. Heavier boats 
 should be protected with sheet copper nailed securely to the 
 bottom. Barges and similar craft should have their bottoms 
 built of lumber heavily creosoted, 12 or more pounds per cubic 
 foot being injected. Even under these conditions, attack is very 
 liable to occur. If fresh-water moorings are accessible the borers 
 in the boats can be killed by anchoring the boats for a few days 
 in fresh water. 
 
 '■ Interest compounded annually at 5 percent. 
 
Plate XIX 
 
 Fig. a. — Sections of longleaf pine piles after 21 months' exposure to the 
 attack of marine borers at Gulfport, Miss. Section to the right, untreated; 
 section to the left, impregnated with a crude oil. (Forest Service photo.) 
 
 (Facing page 186 ) 
 
Plate XIX 
 
 Fig. B. — Untreated pine piles completely destroyed by marine wood borers, 
 Santa Rosa Island, Pla. (Forest Service photo.) 
 
PROLONGING THE LIFE OF PILING AND BOATS 187 
 
 Wood in boats not subject to attack by borers is often quickly 
 decayed, as the moist conditions of the air in them is very 
 favorable to the growth of fungi. It is a very good plan to brush- 
 treat with creosote or carbplineum all such joints subject to 
 decay. The author has had considerable experience in protecting 
 sma;ll fresh- water boats in this manner and has entirely eliminated 
 decay. Of course, the portions so treated cannot be painted, 
 as paint will not adhere to the creosoted wood. In barges and 
 boats where artistic effects are not essential, all lumber subject 
 to decay can be profitably creosoted by one of the empty-cell 
 methods. This will protect the wood from rotting without 
 increasing its weight very materially. 
 
 Although no cases are known of where it has been tried, it is 
 believed that the life of small pleasure boats subject to decay 
 can be materially prolonged if they are filled in the spring with a 
 3 percent solution of copper sulphate or a 1 percent solution of 
 mercuric chloride and allowed to soak in this solution for several 
 days before they are run into the water. These solutions should 
 soak into the joints and permeate the partially decayed wood, 
 thus killing whatever fungi might be present. 
 
CHAPTER XII 
 PROLONGING THE LIFE OF MINE TIMBERS 
 
 On account of the warm damp air which exists in many mines, 
 timber placed in them is very subject to attack by decay and in- 
 sects. As the methods which will eliminate decay will also elimi- 
 nate insects, no differentiation in treatment is specified. It is 
 very common for mine timbers, a foot or more in thickness, to 
 become completely decayed in less than 2 years if set untreated. 
 The expense of resetting these timbers is great, and, furthermore, 
 such replacements generally interfere with the working of the 
 mine. This is particularly true in coal and iron mines. In 
 many mines the walls are of solid rock so that little timber is neces- 
 sary, and even this is often not subject to rapid decay. Also, in 
 temporary workings, where the props are either left standing or 
 "pulled" after the coal or ore has been removed, a preservative 
 treatment is unnecessary. But for permanent shafts and 
 gangways it is highly advisable to so treat the timbers that 
 greatest life can be secured from them and thus the working of 
 the mine will be least interfered with. Several mine com- 
 panies in the United States are using treated timber and have 
 secured excellent results. As the workings are extended deeper 
 and deeper, the need for a preservative treatment is found 
 to become more acute. 
 
 Selection of Species. — It is the practice at most mines to use 
 any kind of wood which is available and is large enough for the 
 purpose desired. Preference is, of course, given to those varieties 
 which are most durable. This freedom in the selection of 
 species must be considered bad practice on the part of the mine 
 operator, for aside from the large expense and trouble to which 
 he is put in replacing the decayed timber, he is filling his mines 
 with the mycelia of the destructive fungi. Sanitation of timber 
 in such conditions is advisable if contamination is to be pre- 
 vented, just as it is among human beings where some are 
 affected with a contagious disease. 
 
 Strength, form, and durability are the inherent properties 
 
 188 
 
PROLONGING THE LIFE OF MINE TIMBERS 189 
 
 required of a good mine timber, but if a preservative treatment is 
 to be given, adaptability to treatment can be substituted for 
 natural durability. As mine timbers, except for shafting and 
 "long walls," are generally short, they are not so difficult to fur- 
 nish as timber for poles and piles, and consequently the mine 
 operator has a wider choice of species at his command. If the 
 timbers are to be set untreated, durable woods should be 
 selected for the permanent workings, such as osage orange, 
 black locust, white oaks, chestnut; or if strength is not so 
 important, the cedars, cypress, etc. The more heartwood they 
 have the longer will be the life secured. 
 
 When treated, the red oak, maple, birch, beech, the hard 
 pines, fir, elm, etc., are good woods where great strength is 
 required, and for workings requiring less strength most any wood 
 having an inch or more of sapwood can be used to advantage. 
 
 The Manufacture of Mine Timbers. — In permanent workings, 
 whether the timbers are to be set treated or untreated, they 
 should be peeled before they are placed in the mine. This in 
 itself will increase their durability and destroy the breeding places 
 for many wood-destroying insects. To peel timber in the woods 
 or at the shipping point effects a saving in freight and in the cost 
 of handling. The weight of the bark usually amounts to from 
 6 to 15 percent of the original green weight. If the timbers are 
 to be treated, they should be framed to exact dimensions so that 
 no cutting into the treated surface will be necessary. Unless 
 there is some good reason to the contrary, all timbers intended 
 for treatment should be left round. Slabbing them only exposes 
 the heartwood and hence decreases the effectiveness of the 
 treatment. 
 
 Methods of Seasoning. — When mine timbers are set untreated 
 there is little or no advantage gained in seasoning them before plac- 
 ing them in the mine. If they are to be treated, however, season- 
 ing is advisable, as it enables better results to be secured. Air 
 seasoning is recommended, unless for some local reason it can- 
 not be practised. Props and other round timbers can be piled 
 on skids in the same manner as poles (see Chapter IX). Mine 
 ties can be piled like railroad ties (see Chapter VIII) . Lumber 
 and sawed stock should be piled with liberal air courses be- 
 tween the planks, and with as small an area as possible in contact. 
 The rules as given in Chapter IV for the selection and care of the 
 seasoning yard should be followed. 
 
190 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 The length of time necessary to air season the timbers of course 
 varies considerably (see Chapter IV). In general, 1 or 2 
 months are sufficient. Fig. 23 shows the rate at which loblolly 
 pine and red oak props and ties air-seasoned in Pennsylvania and 
 Alabama. Whenever possible, timber should be seasoned before 
 shipment, as a considerable saving in freight will result. If it is 
 not practicable to air season the timber, it can be seasoned in 
 steam or oil as described in Chapter IV. The length of time nec- 
 essary to do this will, of course, vary with each kind and form of 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 Description of Material 
 
 
 
 
 V 
 
 
 
 
 
 
 
 
 
 
 Curve 
 
 Bpecies of 
 Timber 
 
 Form 
 
 Dimensions 
 
 le 
 
 5 
 
 V 
 
 ^ 
 
 
 
 
 
 
 
 
 
 A 
 Bo 
 
 CO 
 
 Loblolly Pine 
 
 Loblolly Pine 
 
 Eed Oak 
 
 Mine Props ll'bia.x 10 'Lo 
 Mine Ties 5 x 5'k 5- 4 " 
 Mine Ties 5x5'is'-4' 
 
 ^ 
 
 \, 
 
 ^ 
 
 ^ 
 
 
 
 
 
 
 
 10 
 
 
 \ 
 
 \, 
 
 
 
 -o. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 s 
 
 s 
 
 \ 
 
 
 
 
 ■^ 
 
 ■o~. 
 
 — 
 
 
 C 
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 15 
 
 
 
 \ 
 
 S 
 
 N 
 
 
 
 
 
 
 
 
 
 
 
 
 ^ 
 
 
 
 
 
 
 
 
 
 
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 N^. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 '~~- 
 
 -n 
 
 
 — 
 
 -o 
 
 
 
 
 20 
 
 
 
 
 ^ 
 
 S, 
 
 
 
 "~^ 
 
 ■— 
 
 
 
 A 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 s 
 
 \, 
 
 
 
 
 
 
 ■^ 
 
 
 
 
 
 
 
 
 
 
 
 
 26 
 
 
 
 
 
 
 \ 
 
 \ 
 
 
 
 
 
 
 
 
 
 •^ 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 N 
 
 B 
 
 
 
 
 
 
 
 
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 30 
 
 
 
 
 
 
 
 
 
 ^ 
 
 s.^ 
 
 
 
 
 
 
 
 
 
 
 ■"-• 
 
 ■^ 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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 35 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 ^-^ 
 
 
 — o 
 
 . 
 
 -^ 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 10 
 
 15 
 
 20 
 
 25 30 
 
 Days Seasoned 
 
 35 
 
 40 
 
 50 
 
 56 
 
 Fig. 23.- — Percentage of green weight lost by seasoning mine timbers. 
 
 timber and with the character of treatment desired, so that each 
 plant will have to work out its own best operative conditions. 
 The instructions already given in Chapters IV and V should be 
 consulted for helpful suggestions. 
 
 METHODS OF TREATMENT AND THEIR SELECTION 
 
 Mine Ties. — The methods of treating mine ties do not differ in 
 any essential way from the treatment of cross-ties described 
 in Chapter VIII. If the mines are dry, treatments with zinc 
 chloride or any empty-cell treatment with creosote will prove 
 very satisfactory. On the other hand, if the ties are liable 
 to be wet or alternately dry and wet, heavier injections of 
 
 1 From Bulletin 107, United States Forest Service. 
 
PROLONGING THE LIFE OF MINE TIMBERS 191 
 
 creosote are best. Ties constantly in water need no treatment 
 whatever. 
 
 Mine Props. — Under this heading are included props, legs, 
 collars, and caps. The cheapest treatment consists in brush- 
 treating these with coal-tar creosote, and if the preservative is 
 applied to the ends and joints as well as the sides, several years 
 increase in life will be secured, so that the cost of the opera- 
 tion will more than pay for itself. Such treatments should, 
 of course, be applied to the timbers before they are placed 
 in the mine. If dipped, better results will be secured than 
 by brush-treating, as all checks will be coated with the pre- 
 servative. 
 
 Impregnation treatments have given by far the most satis- 
 factory results. Three processes are recommended, theBurnett, 
 the empty-cell and the full-cell creosote. If decay is not un- 
 usually severe and if the timbers are liable to be broken by crush 
 or "squeeze," the Burnett process is recommended. Excellent 
 results can be secured from it. If the timbers are set in mines 
 where there is much moisture and where decay is very rapid, 
 treatments with creosote should be used, the empty-cell method 
 being employed for porous woods containing much sapwood, as 
 loblolly and shortleaf pines, etc., and the full-cell process where 
 the timbers are refractory and the percentage of sapwood small, 
 as in Douglas fir, hemlock, and hewed timbers generally. One- 
 half pound of zinc chloride per cubic foot is sufficient for the Bur- 
 nett-treated timbers. Six to 12 pounds per cubic foot is sufficiently 
 heavy for the creosoted timbers. All these timbers ean be handled 
 in precisely the same manner as in treating ties. 
 
 The practice of sawing off treated mine timbers in order to 
 make them fit is bad. It can often be avoided by using com- 
 paratively short timbers and wedging them into place by means of 
 creosoted wedges or caps. In this manner much valuable timber 
 can be saved and decay greatly retarded. 
 
 Square Sets. — If these are made of round timbers they can be 
 handled in the same manner as props. If the timbers are sawed 
 or hewn and are not susceptible to treatment, the full-cell creosote 
 treatment is recommended. Care should be taken to see that 
 the ends especially are well protected, and if for any reason 
 it is necessary to retrim these timbers after they have been 
 treated, such places should be brushed over with one or more 
 coats of creosote. 
 
192 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 Lagging. — It seldom pays to treat lagging, but if the lagging is 
 made of sawed lumber, a treatment with zinc chloride can 
 profitably be given. The chief advantage in treating lagging 
 rests in retarding the spread of the wood-destroying fungi. 
 
 The Treatment of Mine Timbers in Relation to Fire. — This is a 
 very important matter, as nothing should be placed in the mines 
 which will increase the fire hazard. All timbers treated with 
 zinc chloride will be more fire resistant than untreated timbers. 
 Furthermore, this salt tends to keep the timbers moist, and 
 hence under pressure they will act more like green timber, viz., 
 bend considerably before they break. Much importance is 
 attached to this property by some mine operators, as it gives a 
 warning to the men in case of a crush or fall of rock or earth. 
 
 In all cases, timbers which are creosoted should first be air 
 seasoned for at least 1 month before they are placed in the 
 mines. This will enable the lighter portions of the oil to 
 evaporate and will decrease very materially the ease with which 
 the timber can be ignited. After it has once air seasoned, 
 creosoted timber is not easily ignited. It is possible to hang the 
 naked flame of a miner's torch or lamp on such timber without 
 injury other than a charring of the surface. If., however, the 
 timber once ignites, it will burn freely and, unfortunately, emit 
 dense clouds of black smoke. Fire in creosoted timber is, how- 
 ever, easily extinguished. The author witnessed the effect of a 
 fire in a mine shaft, built of half untreated and half creosoted 
 props, where the flames shot from the mouth of the shaft. The 
 fire was extinguished by smothering the shaft. An examination 
 made after the fire showed nearly all of the untreated props 
 destroyed, while those creosoted were simply charred on the 
 surface and still serviceable. There is little doubt, however, but 
 what zinc-treated timbers in mines are preferable to creosoted 
 timbers when judged from a fire-hazard standpoint. They are 
 not only fire resistant in themselves, but they do not emit odors 
 which may be objected to by the workmen and hence cause 
 anxiety among them. For further information on the inflam- 
 mability of timber treated with zinc chloride and creosote, the 
 reader is referred to Chapter XVI. 
 
 Cost of Treatments. — Table 30 gives an estimated cost of 
 treating mine timbers. It is assumed that creosote costs 1 cent 
 per pound, zinc chloride 4 cents per pound, peeling and seasoning 
 about 1 cent per cubic foot, brush-treating about 15 cents per 
 
Plate XX 
 
 Fig. a. — Gangway of treated mine timbers, Pottsville, Pa. (Forest Service 
 
 photo.) 
 
 Fig. B. — Rank growth of fungus on mine timbers. 
 
 (Facing page 192.) 
 
Plate XX 
 
 Fig. C. — Treated and untreated mine props. Treated prop to right set 
 at same time as failed untreated prop at left, Pennsylvania. (Forest 
 Service photo.) 
 
 
 ■1 
 
 
 1 
 
 ^^^^^^^^^^^^^^^^^^MHflflilfli^ ^ '^ ^iSI 
 
 1 
 
 ' ^^^^m 
 
 
 1 
 
 
 ^■x'-J^'l 
 
 8 
 
 gb; 
 
 ^ 
 
 ^^^W 
 
 Fig. D. — Untreated mine props destroyed by decay and "squeeze,' 
 Pennsylvania. (Forest Service photo.) 
 
PROLONGING THE LIFE OF MINE TIMBER 
 
 193 
 
 set, and impregnating about 2 cents per cubic foot. A sufficiently 
 close estimate on the cost of treating' mine ties can be secured 
 from a direct comparison with cross-ties already given, rhaking 
 allowance, of course, for the differences in volume between the 
 two. 
 
 Table 30. — Estimated Cost op Untreated and Treated Pine 
 Gangway Sets 
 
 (One aet consista of one 7-£oot -collar, one 9-foot leg, and one 10-£oot leg; average 
 diameter of timber about 13 inohea) " . 
 
 Method of treatment 
 
 Amt. of pre- 
 servative used 
 per set 
 
 Cost of 
 preserva- 
 tive 
 
 Cost of peel- 
 ing, seaaoning 
 treating 
 
 .Total 
 coat of 
 aet in 
 mine 
 
 Uiipeeled. . . 
 
 lb. 
 
 $ 
 
 $■ 
 
 $ 
 8.50 
 8.76 
 9.18 
 10.60 
 12.42 
 9.82 
 
 
 
 
 0.26 
 0.40 
 0.80 
 0.80 
 0.80 
 
 Brushr-treated — creosote 
 
 28 
 130 
 312 
 
 13 
 
 ^0.28 
 
 ^*1 . 30 
 
 3.12 
 
 0.52 
 
 Full-cell process (Bethell) .... 
 Burnett process 
 
 In western United States the cost of treating mine timbers is 
 high. Some figures secured from practice in Montana in treating 
 square timbers are as follows:^ 
 Cost of untreated sets: 
 
 1127 feet B.M. squared timbers, at $20.50 per M B.M 125.36 
 
 Framing timbers 13 . 50 
 
 Cost of lagging, at $15 per M B.M 6.90 
 
 Switching and unloading charges . 85 
 
 Cost of placing set 18 . 00 
 
 Total cost of untreated set in place $63 . 61 
 
 Cost of treatment: 
 
 Cost of treating, including interest, depreciation, fuel, and labor 
 
 charges 3 . 34 
 
 Cost of creosote, at 16.6 cents per gallon; absorption 4.6 pounds 
 
 per cubic foot 8 . 03 
 
 Loading and unloading charges 1 . 23 
 
 Total cost of treatment 12 . 60 
 
 Total cost of treated set in place 76 . 21 
 
 Ecomony of Treatments. — ^Because of the rapidity with which 
 timber placed in most mines decays, the economy due to its 
 treatment is very striking. As stated in the opening of this chap- 
 
 1 Bulletin 107, United States Forest Service. 
 
 13 
 
194 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 ter, it is not advisable to treat all of the timber which is placed in 
 the mine because much of it is intended to serve only a short 
 period. But for permanent shafts, gangways and entries it will 
 almost invariably be found that a treating process of some sort is 
 advisable and will result in a marked economy. Fortunately, 
 some reliable records on the life of treated timber in mines is 
 available on which fairly accurate estimates of economy can be 
 based. (See Chapter XX, Reliable Records on the Life of Treated 
 Timbers.) Excluding all failures from crush and fire, which may 
 be nil or total, the economies that may reasonably be expected 
 when such woods as pine, red oak, etc., are used are shown in 
 Table 31. 
 
 Table 31. — Estimated Annual Charges op Treated and Untreated 
 
 Mine Sets 
 
 (interest 5 percent compounded annually) 
 
 Method of treatment 
 
 Life of 
 timber 
 (years) 
 
 Cost of 
 timber set 
 in mines 
 
 Annual 
 charges 
 
 Untreated 
 
 Brush-treated — creosote 
 
 Burnett process 
 
 Empty-cell process 
 
 Full-cell process (Bethell) 
 
 2 
 
 6 
 
 10 
 
 11 
 
 15 
 
 $8.50 
 
 9.18 
 
 9.82 
 
 10.60 
 
 12.42 
 
 $4.39 
 2.12 
 1.27 
 1.27 
 1.19 
 
CHAPTER XIII 
 
 PROLONGING THE LIFE OF PAVING BLOCKS 
 
 Progress of Wood Paving. — "The first use. of wood for paving is said 
 to have been in Russia, where crude blocks were laid several centuries 
 ago. Wood was introduced into New York City in 1835-36, and into 
 London in 1839. Continental Europe was slower to take it up. 
 
 Dxiring the first 30 years of wood paving in England and America 
 the chief consideration seems to have been the form of block. The large 
 and unequal interstices between the round blocks then commonly used 
 permitted the edges to wear off rapidly into a corduroy condition which 
 was uncomfortable to the traveler, and which hindered both drainage and 
 cleaning, thus making the pavement unsanitary and hastening its decay. 
 To remedy this, other forms of block were devised, many of which were 
 patented. 
 
 In the United States perhaps the most conspicuous of these blocks was 
 the 'Nicholson,' patented in 1848 and laid extensively in the 10 years 
 following the civil war. The block was rectangular, which gave equal 
 interstices; but this by no means solved the problem, and results were 
 no better than before. Little thought was given to the kind of wood 
 used, and as soft a wood as white pine was frequently laid. The blocks 
 were neither seasoned nor treated with chemical preservatives, and 
 quickly decayed. Wide joints permitted water to get under the pave- 
 ment, where it was absorbed by the blocks, with the result that they 
 swelled, so that the pavement often heaved from its foundation. Fin- 
 ally, the foundation was usually of untreated planks, laid directly upon 
 earth, so that they soon decayed, while the pavement sank into ruts 
 and holes. 
 
 Round blocks, mostly of cedar, were extensively laid in the Middle 
 West. They made neither a durable pavement nor in any way a satis- 
 factory one. But they were cheap and served a good purpose in tiding 
 fast-growing cities over a critical period. There have also been laid in 
 various cities pavements of oak, cypress, white pine, hemlock, Washing- 
 ton red cedar, cottonwood, mesquite, Osage orange, redwood, Douglas 
 fir, and tamarack. In nearly all these cases the blocks were untreated, 
 or at most dipped or boiled for a short time in tar, asphalt, or other mix- 
 ture of supposed preservative value, and they failed to give satisfactory 
 results. Untreated American red gum was tried in England, and for a 
 time raised great hopes, but it finally proved unsatisfactory. 
 
 195 
 
196 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 Some species of eucalyptus, especially karri (Eucalyptus diversicolor) 
 andjarrah (E. marginata), which are very dense, hard, Australian woods, 
 have been laid extensively in England. In London these woods have 
 shown a life of from fifteen to twenty years, but continued use has not 
 entirely justified the hopes first entertained for them. Their structure is 
 too dense to permit impregnation with chemical antiseptics, without 
 which they absorb water and swell. They wear much more shppery 
 than most native woods, and they are not immune from decay, though 
 because of certain antiseptic gum-resins which they contain they are 
 more so than any untreated native woods. In England, however, they 
 are still used. Jarrah blocks were laid on Twentieth Street, New York 
 City, in 1895, but were removed in 1904. The cost of this pavement was 
 about $5 per square yard, which would exclude these woods from exten- 
 sive use in America even should they make a better pavement than our 
 best creosoted native woods, which is not likely."' 
 
 The failure of the untreated woods turned attention to blocks 
 artificially preserved. One of the earliest records in our country 
 is in the city of Galveston, Texas, which laid some creosoted pine 
 blocks in 1873. These blocks gave satisfactory service for 30 
 years, when they were destroyed by a flood. Little progress was 
 made in advancing the use of wood blocks until within the past 
 10 years, when the demand for a high-class pavement, especially 
 in large cities, caused a big increase in the number laid. This 
 growth is shown by the following table: 
 
 Table 32. — Amount of Wood Used Annually in the United States 
 FOR Paving Blocks 
 
 Year 
 
 Amount of wood used — cubic feet" 
 
 1907.. 
 
 2,874,560 
 1;260,020 
 2,994,290 
 4,692,453 
 10,145,724 
 7,397,095 
 
 1908 
 
 1909 
 
 1910 
 
 1911 
 
 1912 
 
 " = divide figures given by 2.625 to convert into square yards. 
 
 Mr. George W. Tillson, Chief Engineer, Bureau of Highways 
 of New York City, conducted an inquiry on the comparative 
 value of various forms of pavements in which the opinions of 
 several city engineers were asked in regard to the salient points 
 to be considered in judging a street pavement. Mr. Tillson 
 summarized these opinions in his book entitled "Street Paving 
 
 ' Extract Circular 141, United States Forest Service. 
 
PROLONGING THE LIFE OF PAVING BLOCKS 
 
 197 
 
 and Paving Materials." 
 given in Table 33. 
 
 The results of this investigation are 
 
 Table 33. — Compabative 
 
 Valtje of Different Pavements 
 
 Pavement qualities 
 
 Per- 
 cent- 
 age 
 
 Gran- 
 ite 
 
 Sand- 
 stone 
 
 As- 
 phalt 
 (sheet) 
 
 As- 
 phalt 
 (block) 
 
 Brick 
 
 Mac- 
 adam 
 
 Creo- 
 soted 
 wood 
 
 Cheapness (first cost) . . 
 Durability 
 
 14 
 20 
 10 
 
 14 
 14 
 
 7 
 4 
 4 
 13 
 
 4.0 
 20.0 
 
 9.5 
 10.0 
 
 8.5 
 
 5.5 
 2.5 
 2.0 
 9.0 
 
 4.0 
 17.5 
 10.0 
 11.0 
 
 9.5 
 
 7.0 
 3.5 
 2.5 
 8.5 
 
 6.5 
 10.0 
 
 7.5 
 14.0 
 14.0 
 
 3.5 
 
 4.0 
 
 3.5 
 
 13.0 
 
 6.5 
 14.0 
 
 8.0 
 14.0 
 13.5 
 
 4.5 
 
 3.5 
 
 3.5 
 
 12.0 
 
 7.0 
 12.5 
 
 8.5 
 12.5 
 12.5 
 
 5.5 
 
 3.0 
 
 2.5 
 
 10.5 
 
 14.0 
 6.0 
 4.5 
 6.0 
 8.0 
 
 6.5 
 3.0 
 2.5 
 4.5 
 
 4.5 
 14.0 
 
 9.5 
 14.0 
 14.0 
 
 4.0 
 
 3.5 
 
 4.0 
 
 12.5 
 
 Ease of maintenance. . . 
 
 Ease of cleaning 
 
 Low traction resistance. 
 
 Freedom from slipperi- 
 ness (average of con- 
 ditions) 
 
 Favorableness to travel 
 
 Sanitary quality 
 
 Total number of points 
 
 Average cost per square 
 yard, laid, 1905 
 
 100 
 
 71.0 
 
 73.5 
 
 76.0 
 
 79.5 
 
 74.5 
 
 55.0 
 
 80.0 
 
 
 S3. 26 
 
 J3.50 
 
 S2.36 
 
 $2.29 
 
 J2.06 
 
 9(0.99 
 
 $3.10 
 
 Favorableness to travel is dependent chiefly upon smoothness and freedom from dust and 
 mud, secondarily upon the qualities composing "Acceptability." 
 
 Acceptability includes noise, reflection of light, radiation of heat, emission of unpleasant 
 odors, etc. It chiefly concerns the pedestrian and the adjoining resident. 
 
 Cost per square yard includes concrete, but not excavation, curbing, etc.; except for 
 macadam, which is not usually laid on concrete. 
 
 Other investigators have attempted similar comparative 
 studies, and while no two of them agree in all respects, a high 
 rating is given to wood-block pavement in regard to its noise- 
 lessness, durability, and sanitation. 
 
 On the other hand, the pavement has been severely criticized 
 on account of its high initial cost and troubles experienced with 
 slipperiness, expansion or buckling, and the exudation of oil, or 
 "bleeding." From investigations which have been conducted, 
 it is beUeved that much progress has been made in overcoming 
 some of these objections and that before long all of them, except 
 perhaps high initial cost, will be ehminated. 
 
 Selection of Species. — ^At present most of the wood blocks used 
 (over three-fourths of the total number) are cut from the "south- 
 ern yellow pine." This is rather indefinite as regards the exact 
 species, as the term may include the longleaf, shortleaf, Cuban, 
 or even loblolly pines. What is wanted, undoubtedly, is the 
 longleaf pine, but according to present practice there is no 
 certain way of telling these various pines apart except by a most 
 careful microscopic examination, which in commerical work is, 
 
198 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 of course, impracticable. Specifying a certain number of rings 
 per inch is of assistance but is by no means certain. As the 
 strength of wood is directly proportional to its dry weight, it is 
 believed that a specification coupling rings per inch with dry 
 weight would give the engineer more definitely what he desires. 
 Branding lumber at its point of production would also be of 
 assistance to the inspector. 
 
 In addition to the "southern yellow pine," blocks made of 
 Douglas fir, red gum, tamarack, larch, and Norway pine are also 
 used, although in comparatively small amounts. 
 
 The intrinsic properties demanded of a good block wood are 
 resistance to wear, uniformity in structure and freedom from 
 defects, adaptability to treatment, and ability to hold its shape 
 after treatment. These requirements coupled with a reasonably 
 low cost limit very materially the number of woods which can be 
 used. In addition to the woods already mentioned, it is believed 
 the following are worthy of trial : Beech, birch, black gum, maple 
 sycamore, tupelo, hemlock, lodgepole and western yellow pines. 
 They will, of course, have to be handled somewhat different 
 from standard practice, but some of them possess desirable 
 qualities for street pavements. 
 
 Blocks which are cut from a very hard wood have a tendency 
 to wear smooth, so that unless the pavement is sanded periodically 
 they may prove too slippery for satisfactory use. If some of the 
 woods above suggested give good service in pavements, it should 
 tend in certain cases to lower the initial cost of wood-block 
 pavements. 
 
 The Manufacture of Paving Blocks. — Paving blocks are usually 
 cut from planks of varying lengths, about 3 1/2 to 4 inches thick, 
 and 6 to 10 inches wide. These are fed into the paving-block 
 machine, which is fitted with a series of saws so spaced as to cut 
 the blocks to exact depth. In this manner many blocks are cut 
 at one time. The capacity of the machine varies but good 
 machines can turn out 200 square yards of 4-inch blocks per 
 hour. On leaving the block machine, the blocks fall onto a 
 conveyor, where they are inspected and all imperfect ones 
 removed. The rest are carried mechanically to the treating cyhn- 
 der or cylinder cars and dumped automatically. It is very 
 important that the blocks be cut to an exact depth, for if this is 
 not done the surface of the pavement will be uneven and its wear 
 greatly augmented. The prevailing depth of blocks for street 
 
PROLONGING THE LIFE OF PAVING BLOCKS 199 
 
 work varies from 3 to 4 inches, the smaller being used for light 
 and the larger for heavy traffic. In Europe the practice is 
 to use deeper blocks than in our country. This, of course, greatly 
 increases the cost of the pavement but is claimed to give longer 
 life and greater resilience. It is believed that the question of 
 proper depth of the block is not given the attention to which it is 
 entitled. As all woods vary in strength, it is only reasonable to 
 cut them to different depths depending upon their strength. 
 Blocks are laid with the grain vertical. This subjects them to 
 shear parallel to the grain, which is the weakest direction in which 
 a load can be applied. Failure from shear is therefore great, and 
 many blocks have been shattered in practice because of such 
 failure. It is believed, therefore, that if best service is to be 
 secured, blocks low in shear should be cut to greater depths than 
 blocks which are high. 
 
 The planks from which the blocks are cut are generally air 
 seasoned. It is believed unnecessary to do this, in fact some- 
 times inadvisable. If cut from green planks, the blocks will be 
 treated at their maximum size, so that danger from expansion 
 after they are placed in a street will be lessened. Most woods 
 treat easiest in the direction of the grain, so that the problem of 
 securing a good penetration in blocks only a few inches in length 
 is not a difficult one. 
 
 Specifications for paving blocks vary considerably. The fol- 
 lowing is a fair sample of what is generally required : The blocks 
 shall be made of prime, sound timber, and no wood averaging 
 less than 6 rings to the inch, measured radially from the center of 
 the heart shall be used or wood that is poorly manufactured and 
 contains loose knots, worm holes, and other defects. The blocks 
 shall be from 5 to 10 inches long, 3 to 4 inches in depth parallel to 
 the grain depending upon traffic, and 3 to 4 inches in width, pro- 
 vided all blocks furnished for one street are of uniform width and 
 depth. A variation of 1/16 inch in depth and 1/8 inch in width 
 will be allowed. 
 
 Methods of Treatment.^ — Nearly all of the paving blocks 
 treated in the United States are impregnated with coal-tar 
 creosote, either alone or in mixture with tar, by the full-cell 
 method. In, a few cases, the blocks are simply dipped in oil 
 (creosote or carbolineum) and lately the zinc-creosote process 
 has been advocated for blocks used in factories and shops. A 
 common method consists in placing the air-seasoned blocks in a 
 
200 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 treating cylinder (and sometimes drawing a vacuum), after which 
 the oil is admitted and forced into them under a pressure of about 
 150 pounds per square inch until the desired amount is absorbed. 
 The cylinder is then drained of excess oil and a vacuum drawn for 
 about 1/2 hour to dry the blocks, after which they are removed 
 and are ready for use. This practice is modified by certain opera- 
 tors, who steam the blocks after they are run into the cylinder 
 and then pull a vacuum after the steaming period. A few opera- 
 tors also steam the blocks after they have been impregnated with 
 the oil. 
 
 The amount and kind of oil inj ected varies considerably. Nearly 
 all specifications call for a heavy grade, viz., one with a specific 
 gravity of at least 1.08 at 25° C. and in some cases as high as 1.12. 
 Many engineers allow the oil to be mixed with certain amounts of 
 "filtered tar" in order to bring up its gravity. Some also allow 
 water-gas-tar creosote to be mixed with the coal-tar creosote. The 
 amount of oil required is generally 16 pounds per cubic foot, al- 
 though this varies from 12 to 20. It can thus be seen that the 
 practice in treating blocks is by no means a uniform one, but dif- 
 fers with the opinions of the various engineers. 
 
 The Chicago Creosoting Company has recently constructed a 
 block plant wherein the cylinders are placed vertically. (See 
 Plate XI, Fig. D.) The blocks are dumped into the top of the 
 cylinders by a mechanical conveyor. After the desired absorp- 
 tion has been obtained, the excess oil is drained from the cylin- 
 ders, and a door in the bottom of the cyUnder is opened allowing 
 the blocks to fall directly into cars ready for shipment. This 
 method does away with cylinder cars entirely and is claimed to 
 cut down the cost of handling. 
 
 Troubles Experienced with ■Wood-block Paving. — It has al- 
 ready been stated that wood-block paving at times has serious 
 objections. Unfortunately, the exact cause of these difficulties 
 is not known at present, so that definite remedies for all conditions 
 cannot be prescribed. Opinions and practice differ widely. The 
 chief objections are slipperiness, exudation of oil, and expansion of 
 the blocks. 
 
 Slipperiness. — In general, the harder the blocks the smoother 
 the pavement becomes. Blocks of softer wood give, therefore, 
 less trouble from slipperiness, but there is a limit to which the 
 softness can go, as blocks which are too soft will of course wear 
 rapidly. 
 
PROLONGING THE LIFE OF PAVING BLOCKS 201 
 
 Oil and tar on the surface of the pavement also increases 
 slipperiness. It is believed that this cause can be largely over- 
 come as will be discussed below. 
 
 If our streets were sanded from time to time, as is done abroad, 
 the surface of the blocks would become roughened because the 
 sand would embed itself in the wood. This should be done 
 particularly in cold weather, when ice forms on the pavement. 
 Asphalt is also subject to the same objection in cold weather and a 
 similar treatment should be given it. 
 
 Exudation of Oil. — This is about the most troublesome objection 
 raised against wood blocks. The oil and tar may at times exude 
 to the surface and form a thick, disagreeable mat, which sticks 
 to the feet of pedestrians and is generally objectionable. In 
 certain cities like Chicago, the trouble became so acute as to 
 arouse bodies of citizens into a protest against what was termed 
 the "black plague." Other cities like Minneapohs have for- 
 tunately been free from these troubles. It is probable that the 
 exudation of oil, commonly called "bleeding" or "weeping," 
 is due to several causes, such as too heavy an impregnation, too 
 much pitch or tar poured into the joints, too rapid-grown blocks, 
 improper treatment, and too close laying of the blocks. From 
 observations and tests made by the author it is believed that 
 bleeding can be eliminated if (1) only slow-grown wood is used 
 for the blocks; (2) if green timber or steamed seasoned timber 
 is used; (3) if a strong preliminary and final vacuum is drawn 
 before and after the oil is injected; (4) if when tar is used the 
 blocks are steamed slightly after the oil is injected; (5) if the 
 penetrations are made complete; (6) if impregnations no greater 
 than 16 pounds per cubic foot are given; (7) if straight coal-tar 
 creosote or coal-tar creosote containing only small amounts of 
 carbon-free tar is injected; (8) if the blocks are not laid too close 
 together; (9) if excess tar or pitch is not poured between the 
 joints. All of these requirements can be easily met without added 
 cost. 
 
 Expansion of the Blocks.— This is commonly called "mush- 
 rooming," "buckling," or "pop ups." (See Plate XXI, Fig. A.) 
 The true cause of it is not known except, of course, that the 
 blocks are under heavy pressure. If the blocks are laid very 
 dry and close together there will be little room for expansion and 
 the pavement will be very liable to buckle. It is believed that 
 if the blocks are well penetrated so that their tendency to absorb 
 
202 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 moisture will be decreased, are treated green or steam seasoned, 
 are laid fairly loose and have proper expansion joints, little or 
 no trouble from buckling will be experienced. 
 
 It is wasted effort to try and make the blocks nonexpansive, 
 for no matter how much oil is forced into them they will absorb 
 more or less water in time. Furthermore, the oil and wood will 
 expand due to rise in temperature. Best practice, therefore, is to 
 keep the absorption of water to a minimum by proper treatment 
 and to allow for expansion by carefully laying the pavement as 
 described above. 
 
 JMethod of Laying Wood Blocks. — In street work, a concrete 
 base about 4 to 8 inches thick is first constructed, this having the 
 desired crown. Over this is then placed a layer of coarse sand 
 about 1 inch thick. The blocks are then laid on this smoothed 
 sand cushion, after thich they are tamped and rolled into final 
 position. Asphalt, grout, or hot pitch is then poured into the 
 joints and further worked into them with a squeegee. The 
 surface is then covered with sand and the pavement is ready for 
 use. In a few days the excess sand is removed from the pavement. 
 
 Experiments have been tried in doing away with the sand 
 cushion by pouring hot pitch directly over the concrete base and 
 embedding the blocks in it. These pavements have not been in 
 service sufficiently long to judge of the results. 
 
 The angle at which the blocks are laid has also been tested. 
 It is found that blocks laid at an angle of 671/2° with the curb 
 show least wear, those at 45° next, and those at 90° most. 
 
 The character of filler to be used is still an open problem. 
 Coal-tar pitch and asphalt seem to be preferred. The former is 
 objectionable in that, if not properly applied, it will ooze to the 
 surface. Asphalt is free from this objection but is more difficult 
 to work into the joints. 
 
 Expansion joints are, at times, laid not only along the curb 
 (about 1 inch in width on a 50-foot roadway) but crosswise. 
 
 In some cities strips of wood about 1/4 inch thick are 
 placed between the blocks, thus leaving joints for a better footing 
 of horses. This practice, however, is not common. 
 
 When wood blocks are used on certain types of bridges, they 
 are laid directly upon creosoted plank. This adds considerably 
 to the lightness of the bridge and is considered a distinct 
 advantage over other forms of pavement. 
 
 Cost of Treatment. — The cost of treating wood paving blocks 
 
Plate XXI 
 
 assee^r"' 
 
 Fig. a. — A "popup," or failure in a street laid with creosoted blocks due 
 
 to their expansion. 
 
 Fig. B. — Wood block pavements — grading the sand cushion and laying the 
 blocks, Minneapolis, Minn. (Forest Service photo.) 
 
 {Facing page 202.) 
 
Plate XXI 
 
 Fig. C. — Working the tar filler into the joints of a newly laid wood block 
 pavement. (Forest Service photo.) 
 
 Fig 
 
 -Pine beams in a building completely rotted in the end after 30 
 years' service, Madison, Wis. 
 
PROLONGING THE LIFE OF PAVING BLOCKS 203 
 
 varies with the kind of oil specified, the amount to be injected, the 
 kind and size of the block, and other peculiarities in the specifica- 
 tions. If ordinary creosote is used it can be obtained for about 
 8 cents per gallon. Generally, however, a higher grade is re- 
 quired, which in some cases costs 12 to 15 cents or more per 
 gallon. Assuming the cost of the oil to be 1 cent per pound 
 and 16 pounds to be injected per cubic foot, the cost of treating a 
 square yard of 3 1/2-inch blocks will be about 45 to 50 cents, and 
 of 4-inch blocks about 52 to 57 cents. This, of course, is but a 
 fraction of the total cost of the pavement, which, in general, 
 varies from about $2.20 to 13.70 per square yard, making it one 
 of the most expensive pavements in use. 
 
 Advantages of Wood-block Paving. — Wood-block pavements 
 possess some very desirable properties, the chief ones being 
 sanitation, durability, ease of repair, low traffic resistance, ease of 
 cleaning, and absence of noise. Friends of the pavement will 
 find many other points to extoll, but the above list may be 
 considered conservative. 
 
 Coal-tar creosote is a strong antiseptic, and as large quantities 
 of it are forced into the blocks, its presence alone tends to keep 
 the street in a healthy, sanitary condition. 
 
 The durability of wood blocks when properly laid is surprising. 
 Data collected on a test pavement in Minneapolis, where ac- 
 curate traffic records are kept over one of the busiest streets in 
 the city, show a wear of about 1/32 inch per year. The expe- 
 riences of several cities have shown the marked value of wood 
 blocks in comparison with the durability of other kinds of 
 pavement. There is no doubt but what the good results already 
 obtained could be considerably bettered if American munici- 
 palities only took better care of their pavements. In this respect 
 Europe is far ahead of us. 
 
 The ease with which wood-block pavements can be repaired 
 is all the more reason why better care should be taken of them. 
 If a depression once starts it will grow rapidly until a considerable 
 hollow is formed. The time to repair such failures is in their 
 beginning when all that is necessary is to remove a few blocks, 
 smooth the sand cushion, and add new ones. 
 
 The depressions caused by vehicles and horses in asphalt on 
 hot days is well known. This, of course, means the load is 
 harder to pull. Wood blocks do not have this objection and 
 because of their smooth surface make traffic run smooth. 
 
204 THE PRESERVATOIN OF STRUCTURAL TIMBER 
 
 The even surface of wood-block pavements enables them to 
 be easily cleaned and, of course, adds to their santitation. 
 
 It is perhaps the noiselessness of wood blocks which makes 
 them so desirable, especially in congested business districts, 
 and has earned for them the title of the "silent pavement." 
 This quality has placed wood-block pavements in high regard 
 and is largely responsible for their rapid growth in our large 
 cities. 
 
 In all of the above, it has been assumed that the pavements 
 were properly laid, for if this is not done poor results are bound to 
 follow. There is no unusual difficulty in properly laying a wood- 
 block pavement. 
 
 Wood Blocks for Barns, Factories, Etc. — Considerable progress 
 has been made within the past few years in introducing wood- 
 block flooring in factories, car barns, ferry ships, etc., where it 
 has given good service. It is liked by the workmen in preference 
 to cement floors because of its "touch." It is durable, easily 
 repaired, sanitary, and dustless. For use under such conditions 
 the blocks are often cut smaller and treated with less oil than 
 blocks intended for streets. In fact, the Rueping and Card 
 processes are sometimes employed, thus decreasing perceptibly 
 the cost of treating the blocks. The blocks are laid in much the 
 same manner as for street work except that the angle of the 
 courses is almost invariably 90°. 
 
CHAPTER XIV 
 PROLONGING THE LIFE OF SHINGLES 
 
 Shingles are subject to common forms of destruction, (1) 
 decay and (2) fire. If made from durable woods, the problem 
 of protection from decay is not serious, as shingle roofs may 
 easily last 25 years or more. Protection from fire is of greater 
 importance, especially where the houses are close together. In 
 congested districts the use of shingles is now almost entirely 
 obsolete. However, shingle roofs possess certain desirable 
 properties so that their use in dwellings will undoubtedly continue 
 to be extensive. 
 
 Selection of Species. — In round numbers about 15 billion 
 shingles are used annually in the United States, about 75 per- 
 cent of which are of cedar — mostly the western red cedar of 
 Washington. Next in rank come cypress and yellow pine, each 
 furnishing about 9 percent. Then redwood with 3 percent, white 
 pine 2 percent, and spruce 1 percent. The other species such as 
 chestnut, hemlock, western pine, and oak all furnish less than 
 1 percent. With the exception of oak and chestnut, the total 
 cut of which is insignificant, it will be noticed that all of the 
 shingles are made from coniferous woods. 
 
 The ideal shingle is one which is light in weight, durable, and 
 will "lay flat" without checking, warping, or splitting. Western 
 red cedar admirably meets these requirements. Excellent service 
 is also secured from cypress and redwood shingles, both of which 
 possess remarkable durability. 
 
 The best grades of shingles are cut only from clear timber free 
 from all defects. Sapwood is also excluded, since it is not very 
 decay resistant. If, however, the shingles are given a thorough 
 preservative treatment, sapwood should not be considered a 
 defect, and in some cases treated sapwood shingles can be obtained 
 at no greater cost than untreated shingles of all heartwood. 
 
 METHODS OF TREATING SHINGLES 
 
 Treating against Decay. — The most common method of pro- 
 tecting shingles from decay is to dip them in a preservative and 
 
 205 
 
206 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 after they have dried nail them on the roof. There are several 
 preservatives sold on the market for this purpose under the name 
 of "shingle stain," which not only preserve the shingle but color it. 
 For best results, the shingles should be thoroughly air dry when 
 they are dipped and the preservative should be warm or even 
 hot. As a general rule, only that portion of the shingle which is 
 exposed is dipped, the upper or thinner portion being in this 
 manner covered by the treated portion of the shingle next above 
 it on the roof. Roofs laid in this manner are frequently given a 
 final coating of preservative after they are laid, in order to insure 
 a uniform color and the treatment of all exposed portions. 
 
 Cheaper and less efficient results are obtained if the shingles 
 are simply brush-treated with the preservative after they are laid. 
 It is doubtful if ordinary paint preserves the life of shingles; in 
 fact, it may hasten their decay. Paint is of value, however, in 
 certain cases, in that it tends to make the shingles lie flat and 
 hence prevent leaks. 
 
 Most efficient results in treating shingles against decay con- 
 sists in impregnating them with the preservative. This is 
 done either in open tanks or pressure plants. The absorption 
 of the preservative should not be so great as to unnecessarily 
 increase the cost of the shingles or cause them to ooze and 
 drip oil on hot days. An absorption of 10 pounds per bundle 
 is aniple. In either of these processes the shingles can be 
 treated in the bundle, provided they are not strapped too tight 
 together. If the open-tank process is used the shingles should 
 be removed while hot; if the pressure process is used, a final 
 vacuum should be drawn. These manipulations are advisable in 
 order to dry the shingles. If treated in this manner sap shingles 
 can be made as resistant to decay as heart shingles, and inferior 
 shingle woods like hemlock and yellow pine made exceedingly 
 durable. 
 
 Shingles treated with creosote or the so-called shingle-stains 
 have a very strong odor which to many people is objectionable. 
 This odor, however, decreases with age and in time ceases en- 
 tirely. Furthermore, the rain-water off a freshly treated roof is 
 very liable to smell and taste of the preservative at least until the 
 roof has been exposed for several weeks. 
 
 Treating against Fire.— Practically nothing has been done to 
 date in treating shingles against fire. The recent agitation against 
 shmgle roofs in certain cities, has, however, caused considerable 
 
PROLONGING THE LIFE OF SHINGLES 207 
 
 interest in this matter and several concerns are now at work 
 attempting to render shingles noncombustible. Ordinary fire- 
 proofing compounds like ammonium chloride, ammonium phos- 
 phate,, etc., are objectionable in that they are soluble in water and 
 consequently will soon be washed from the wood. It is possible, 
 however, that their use might be rendered practicable by paint- 
 ing the shingles treated in this manner with a waterproof paint 
 after they have been laid. A large variety of experiments are 
 now under way, some of which indicate hope of a satisfactory 
 solution of the problem, but at this writing no method that 
 can be called successful is known. Greatest danger from fire 
 is caused by the shingles curling and igniting from sparks or 
 brands. If the shingles ''are made to lie flat their liability to 
 catch on fire from such sources is greatly decreased. Some of the 
 so-called "fireproof" paints now on the market are of value in 
 this respect and tests known to the author have indicated that 
 even ordinary paint will be found of material assistance. 
 
 Cost of Treating Shingles. — If shingles are impregnated with 
 creosote, the cost will be about $1.25 to $1.75 per thousand. If 
 they are simply dipped into the creosote the cost will be about 
 $0.60 to $1.50 per thousand; if brush-treated with two coats after 
 the roof is laid, about $0.40 to $0.90 per 100 square feet. Shingle 
 stains which cost from about $0.40 to $1 per gallon make, of 
 course, a more expensive treatment, the cost of dipping per thous- 
 and being about$1.50to $3.50, and for simply brush-treating after 
 the roof is laid about $0.60 to $1.50 per 100 square feet. 
 
CHAPTER XV 
 PROLONGING THE LIFE OF LUMBER AND LOGS 
 
 Methods of Treating Lumber for Rough Construction. — An 
 
 immense quantity of structural timber is used annually in the 
 United States under conditions which subject it to decay. Un- 
 fortunately, only a small percentage is treated, so that our 
 depreciation losses are both rapid and large. Of course, wherever 
 the timber can be protected from the weather, or warm damp at- 
 mosphere, no artificial treatment is necessary, as it willu nder such 
 conditions last indefinitely. However, in bridges, trestles, piers, 
 walks, platforms, docks, etc., etc., where such timbers are used, 
 failure from decay is all too common. (See Plate XXI, Fig. D.) 
 This is particularly true.if the wood comes in contact with the 
 soil. While it is not possible to lay down a set of instructions 
 which will cover all cases, certain general rules should, however, 
 prove of direct value to those using this class of material. 
 
 Whenever possible, all such timbers should be kept from 
 contact with the ground. In many cases, they can be placed 
 on concrete or stone piers, and by this simple treatment, their 
 life considerably prolonged. 
 
 The most effective treatment which can be given such timbers 
 is to impregnate them with coal-tar creosote. For severe cases, 
 the full-cell process should be used; for less severe, the empty- 
 cell or Card. From 5 to 12 pounds of oil should be injected, 
 depending upon local conditions. As sapwood is just as strong as 
 heartwood, the treatment of this kind often enables the use of 
 sappy timbers, which, untreated, would not be used. Hence, 
 specifications for the raw material can be made more lenient and 
 the timber can frequently be secured at a lower initial price. All 
 structural timbers injected with preservatives should be framed as 
 close to final dimensions before treatment as possible. 
 
 Next to impregnation treatments, brush treatments with a 
 high-grade coal-tar creosote are recommended. If these are 
 
 208 
 
PROLONGING THE LIFE OF LUMBER AND LOGS 209 
 
 used, the wood should first be thoroughly air seasoned and dry 
 at the time the preservative is applied, otherwise little or no 
 beneficial results will be secured. Two coats are better than one, 
 and in all cases the oil should preferably be brushed on hot (about 
 150° to 175° F.), care being taken to soak especially all joints, 
 bolt holes, and laps. 
 
 In timbers which decay only at the joints, the joints only need 
 be coated with hot creosote, the rest of the member being left 
 untreated. All joints made in timber which has been impreg- 
 nated should always be brush-coated with hot creosote if these 
 are framed after treatment. 
 
 Timbers treated with creosote cannot as a rule be painted, as 
 the paint will not adhere to them. They will, however, be turned 
 a deep brown which, on prolonged exposure, will become lighter 
 in color. For rough construction, the oil will take the place 
 of paint, and in this connection also effect a saving. 
 
 Methods of Treating Ltunber for Buildings, Greenhouses, and 
 Cars. — In general lumber used in buildings, cars, etc., cannot be 
 creosoted because it is desirable to paint it, and as mentioned, 
 paint does not readily adhere to creosoted wood. In certain 
 cases, however, this is not necessary. For example, sills in build- 
 ings, beams in porches, etc., where the wood is covered, can be 
 profitably treated. Thus the sills and beams used in constructing 
 the so-called "Sanitary floors" in the South, particularly New 
 Orleans, are impregnated with 10 to 12 pounds of creosote per 
 cubic foot, and very good results obtained. Even in silos, if it is 
 not desired to paint them, creosoted lumber can be used to ad- 
 vantage provided it is permitted to air season before the silos are 
 filled. 
 
 When the wood is to be painted, a treatment with one of the 
 antiseptic salts is recommended. Zinc chloride, mercuric chloride 
 copper sulphate, or sodium fluoride will all give good results. As 
 mercuric chloride and copper sulphate cannot be used in steel 
 cylinders, it is necessary to soak the lumber in stone, concrete, 
 or wooden vats containing these preservatives. This is done as 
 described under the Kyanizing process. These salts have a 
 further disadvantage in that they will attack the steel in 
 carpenters' tools. Zinc chloride and sodium fluoride can be 
 handled as described in the Burnett process. The lumber should 
 then be air seasoned before it is placed in the building, after 
 which it can be handled like untreated lumber. Paint of all colors 
 
 14 
 
210 THM PRESERVATION OF STRUCTURAL TIMBER 
 
 will in general adhere readily to wood treated with the salts just 
 mentioned, and will aid materially in holding them in the wood. 
 Treatments of this kind are recommended particularly for such 
 places as floors and columns in porches, trim around the eaves, 
 bench boards and sills in greenhouses, roofs in dye houses, and in 
 fact, all places where the wood is subject to decay, and where it is 
 necessary to pain it with light colored pigments. Much has been 
 written of "dry rot" in buildings. This can be greatly re- 
 tarded or prevented by the treatments described, since it is caused 
 by a fungus. In all cases, the lumber should be framed to as 
 near the exact dimension it is to have as can be done because 
 any subsequent cutting will expose the untreated interior and 
 hence shorten the life of the wood. It is believed that there is a 
 good field for many lumber companies to operate treating plants 
 for preserving wood used in building construction. By so doing, 
 woods which are not naturally durable could be made to compete 
 with the more expensive and naturally durable woods like cypress, 
 cedar and redwood, and would in certaip cases be preferable in 
 that some of them possess greater strength. Treatments with 
 the above salts will also resist insect attack. 
 
 The life of untreated wood can be prolonged in many cases by 
 keeping a circulation of dry air about it. Stagnant air in 
 cellars or store rooms is particularly liable to start decay, and it 
 frequently happens that by simply improving the ventilation, 
 further decay can be arrested. Of course, when untreated 
 wood is used, sap wood is a detriment and " all heart" pieces are 
 always to be preferred. In certain types of flooring, creosoted 
 planks can first be laid and then faced with thinner planks of 
 untreated wood. If timber is set subject to decay, ordinary 
 paint will seldom arrest the decay unless all surfaces of the wood 
 are treated. In fact, the paint may actually hasten decay in some 
 instances, as for example, when only one or two surfaces are 
 painted and the others are left unpainted. The unpainted 
 surfaces will absorb moisture, while the painted surfaces will 
 retard it from evaporating, and thus the wood will actually have 
 more moisture in it and in such a condition be more susceptible 
 •to decay. This is a common occurrence in the floors of outdoor 
 porches, the upper side of which is usually the only surface 
 painted. 
 
 It has been reported that dry rot in factories can be checked 
 by raising the temperature in the rooms to 120° F. or more for a 
 
PROLONGING THE LIFE OF LUMBER AND LOGS 211 
 
 few hours. The author is unable to verify these reports but 
 beUeves the treatment well worthy of trial by those troubled 
 with this form of decay. 
 
 Methods of Preserving Logs from Decay. — It is very difficult 
 to store logs with bark on them for any length of time without 
 their being attacked by decay. This is particularly true of logs 
 having much sapwood, like the gums, sycamore, maples, birch, 
 etc. Decay can be retarded if the ends of these logs are given one 
 or two coats of creosote as soon as possible after they are cut. 
 The same should be done wherever the bark has been broken off. 
 If it is simply desired to retard checking, the ends of the logs 
 should be coated with paint, or better still, hot paraffin. In this 
 way the logs can be protected at a cost of only a few cents per 
 thousand feet of lumber. To protect logs from insect attack, it 
 is necessary to peel them or soak them in water. In special 
 cases, the methods described below might be used. 
 
 Methods of Treating Log Cabins and Rustic Furniture. — No 
 satisfactory method of keeping bark on wood for any appreciable 
 length of time is known, particularly if the bark is soaked by 
 rain from time to time. Fungus and insects are both very apt 
 to work in under the bark and cause it to fall off. 
 
 Damage of this kind can be largely prevented by cutting the 
 logs in late autumn and piling them so that they will dry as 
 rapidly as possible or by utilizing them immediately. Even 
 better, but more expensive and troublesome results can be ob- 
 tained by cutting the logs in the spring and stripping them in 
 laps of bark, which at this season peels readily. The bark can 
 then be soaked in a 1 percent solution of mercuric chloride 
 and the logs used directly. After the logs have air-dried, they 
 can be brush treated with one or two coats of coal-tar creosote or 
 carboHneum. When this has dried for several days, the bark can 
 then be nailed to the logs. Treatments of this kind are the 
 most effective known. Care should be taken in handling the 
 mercuric chloride solution as this is extremely poisonous, and 
 also in thoroughly air-seasoning the treated logs so that the 
 odor of oil will not prove objectionable. 
 
 Rustic furniture should be kept under cover and dry. Little 
 or no trouble will then be experienced with decay. Insects; 
 however, may attack it, as is evidenced by little mounds of saw- 
 dust and miniature pin holes in the bark. Sponging such 
 furniture thoroughly with kerosene or benzene will usually 
 
212 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 kill the insects and stop their depredations. Or if the 
 holes are caused by larger wood-boring insects, carbon bisul- 
 phide can be injected into the holes, which should then be im- 
 mediately stuffed with putty, or a similar substance. The 
 offensive odor of the bisulphide will leave the wood in a few days. 
 
CHAPTER XVI 
 THE PROTECTION OF TIMBER FROM FIRE 
 
 The use of wood as a construction material, especially in con- 
 gested centers as in cities, has a serious objection due to the 
 comparative ease with which it can be ignited and with which 
 it burns. The objection to its use because of this property is 
 rapidly growing and will undoubtedly continue to do so. The 
 fire losses in the United States are enormous, reaching the vast 
 sum of $215,000,000 per year. Of course, all of this is not due 
 to the use of structural wood, as the contents of even "fireproof" 
 buildings are inflammable and are frequently destroyed. A few 
 cities have already passed ordinances prohibiting the use of 
 natural wood in buildings over a certain number of stories in 
 height, and other cities have specified against the use of wooden 
 shingles within their more congested limits. Such action has 
 attracted keen attention of late to the possibiUty of rendering 
 wood noncombustible. This problem is quite different from the 
 problem of protecting wood from decay and has to do almost 
 entirely with the control of the gases driven off from wood when 
 heat is applied to it. If these gases can be diluted with a non- 
 combustible gas in proper proportions, the wood will charr and 
 not burn. On the other hand, if these gases can be kept from 
 mixing with requisite amounts of oxygen, a similar result can 
 be secured. In either event, the original properties of the wood 
 will be destroyed, so that, strictly speaking, it is practically 
 impossible, if not impossible, to render wood "fireproof." The 
 best that can be expected is to either make the wood noncom- 
 bustible or slow burning. The temperature at which natural 
 wood will ignite under ordinary conditions is about 500° F. The 
 temperature of a burning building is estimated at about 1700° 
 F. The ease with which natural wood ignites, therefore, when 
 subjected to such high temperatures, is readily seen. As great 
 progress in protecting wood from fire has not been made thus far 
 as in protecting it from decay, and but two companies are now 
 in operation in this country. Progress has been considerably 
 
 213 
 
214 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 retarded by fraudulent practices on the part of defunct companies 
 claiming to "fireproof" wood, and by contractors who claimed 
 to use such wood in their construction. Furthermore, a gross 
 misunderstanding exists concerning the possibilities of render- 
 ing wood noncombustible, which has often led to the drafting of 
 impracticable specifications. Much work remains to be done in 
 perfecting present methods and in enlightening the public to 
 what can reasonably be expected. 
 
 The chief objections raised against the use of "fireproofed" 
 wood aside from increased cost are the leachability of the 
 chemicals, their corrosive action on metals, their effect on the 
 strength of the wood, and their action on paints and varnishes. 
 Wood impregnated with the best known fire retardent chemicals 
 cannot be set in wet or damp situations or exposed to the 
 weather, as the chemicals will be leached from the wood. Nails, 
 hinges, etc., in contact with such fireproofed wood will, when it 
 becomes damp, be corroded. Wood treated with these chemicals 
 is rendered more brittle than wood not treated, although the loss 
 in strength can be greatly decreased by proper methods of treat- 
 ing and drying. For many purposes, as in trim in buildings, the 
 question of decreased strength should have little or no serious 
 consideration, as this property is not important. Due to their 
 hygroscopic nature, the salts are quite liable to keep the wood 
 moist and hence interfere with the adhesion of paint or varnish. 
 
 When not exposed to the weather or unusual dampness, "fire- 
 proofed wood, " as it is now known, has given very satisfactory 
 service. It retains its resistance to fire for long periods, and, so 
 far as its other properties are concerned, behaves in much the 
 same manner as untreated wood. 
 
 The Theory of Rendering Wood Fire Retardent.- — Those results 
 which have been most successful thus far have been founded 
 on one or more of the following theories: 
 
 1. To cover the wood with a chemical which, like sodium 
 silicate, when heated will fuse over the surface and prevent a free 
 access of oxygen to the wood. 
 
 2. To cover the wood with a noncombustible material which, 
 like asbestos or metal, will prevent a free access of oxygen to the 
 wood and thus produce a slow distillation. 
 
 3. To impregnate the wood with a chemical which, like borax, 
 when heated will liberate water vapor or steam, thus diluting the 
 combustible gases so that their ignition cannot occur. 
 
THE PROTECTION OF TIMBER FROM FIRE 215 
 
 4. To impregnate the wood with a chemical which, like salts 
 of ammonia, when heated will liberate a noncombustible gas, 
 thus diluting or combining with the combustible gases so that 
 combustion is impossible. 
 
 Owing to their manner of appUcation, these various theories 
 can be classified into two groups of treatment which may be 
 called superficial and impregnation processes. 
 
 Superficial Processes.^ — These consist in protecting the surface 
 of the wood from contact with flames. If the protective coating 
 is a liquid like sodium silicate, it is simply painted onto the 
 wood or the wood is dipped into it. Such treatments, while 
 effective in retarding the ease with which the wood will catch on 
 fire, are not conducive to best results. Other superficial proc- 
 esses consist in covering the exposed surface of the wood with a 
 noncombustible material such as asbestos or metal. Unless the 
 covering entirely surrounds the wood, the temperature of the 
 protected face may become so high as to cause the wood to 
 ignite. When, however, the covering entirely surrounds the 
 wood the protection is very efficient as burning is almost entirely 
 excluded and only charring is produced. As might be surmised 
 from its manner of application, this method of treatment has 
 only a limited use and is quite costly. 
 
 Impregnation Processes. — These are conducted at the present 
 time in much the same manner as the Bethell or Burnett processes ' 
 (see description) of protecting timber from decay. They 
 differ from them in two respects: (1) different chemicals are 
 used, and (2) the wood is generally kiln-dried after the chemicals 
 have been forced into it, in order to remove the large amount of 
 water injected into it. As a general rule, only thoroughly air- 
 seasoned wood is treated, this usually in the form of rough sawn 
 lumber. The kiln drying of " fireproof ed" timber requires a 
 nice adjustment in that the temperatures used must not be so 
 high as to volatilize the chemicals injected or cause them to " pull " 
 toward the surface. Checking and warping must also be guarded 
 against. Any efiicient kiln-drying process can, however, be 
 employed provided it is properly applied. 
 
 Chemicals, Used.; — A large variety of chemicals hve been tested 
 by various experimenters in the attempt to render wood non- 
 combustible. The more ipiportant of these chemicals thus 
 tried, either alone or in combination, are: Anymonium sulphate, 
 phosphate and chloride, zinc sulphate and chloride, borax, 
 
216 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 cresylates of mercury, lead, copper, iron, and zinc, sulphate of 
 iron, alum, calcium bisulphite and lime, sodium silicate, oxalic 
 acid, potassium and sodium carbonate. Best results have been 
 secured with the salts of ammonia, borax, and sodiuin silicate. 
 
 "Fireproofing" tests have been made at the U. S. Forest 
 Products laboratory on noble fir, using the following fire-retarding 
 agents. 1 
 
 strength of solution 
 
 Amount dry salt in- 
 jected per cubic foot 
 of wood 
 
 
 11 pounds 
 11 pounds 
 10 pounds 
 5 pounds 
 5| pounds 
 
 
 30 percent solution oxalic acid 
 
 20 percent solution borax 
 
 20 percent solution ammonium chloride 
 
 CHEMICAL FIRE RETARDENTS 
 
 Sodium Carbonate. — ^Sodium carbonate did not prove efficient 
 in retarding combustion (Fig. 24). It also caused a marked 
 weakening of the wood. 
 
 Sodium Bicarbonate. — Sodium bicarbonate did not prove 
 efficient in retarding combustion (Fig. 24), and also caused a 
 marked weakening of the wood. 
 
 Oxalic Acid.- — Oxalic acid did not prove efficient in retarding 
 combustion (Fig. 24), and also caused a marked weakening of 
 the wood. 
 
 Borax.: — Borax was of considerable value in retarding com- 
 bustion (Fig. 24). The dotted curve (G), Fig. 24, shows the 
 comparison with natural wood and the other fireproofing agents 
 used. The points determining the position of this curve were 
 obtained after the piece had become charred and incandescent. 
 A small amount of an inflammable gas, probably carbon mon- 
 oxide was generated, which burned with a small blue flame on 
 the top of the test specimen, but only with the aid of the pilot 
 light. 
 
 Ammonium Chloride. — Ammonium chloride proved of con 
 siderable value in retarding combustion (Fig. 24). . The points 
 determining the position of the dotted curve (F), Fig. 24, repre- 
 sent the same condition as was described under borax. How- 
 
 ' From Proceedings American Wood Preservers' Association, 1914, by 
 Robert E. Prince. 
 
THE PROTECTION OF TIMBER FROM FIRE 
 
 217 
 
 ever, amlnonium chloride is somewhat hygroscopic and its use 
 may be restricted for this reason. 
 
 Commercial Treatment.: — A number of tests were made on 
 pieces of red oak, treated by a commercial fireproofing company 
 with a solution containing ammonium phosphate and ammonium 
 sulphate. The strength of the solution was not known. Am- 
 monium phosphate and sulphate proved of considerable value in 
 retarding combustion. 
 
 Tests to Determine the Inflammability of Timber. — Several 
 methods of testing the inflammability of wood have beeit sug- 
 
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 100 126 160 136 200 
 
 226 260 276 300 326 360 
 Temperature-Degrees Centigrade 
 
 376 400 426 450 476 
 
 Fig. 24. — Time required to ignite natural wood and wood impregnated with 
 fire retardent chemicals when subjected to various temperatures. 
 
 gested. The more common of these are the shaving test, crib 
 test, spot test, and electric furnace. 
 
 Shaving Test. — Shavings planed from the treated wood are 
 placed in a wire basket over a Bunsen burner. Notes are taken 
 on the length of time required to ignite the shavings, the character 
 of the burning, the length of glow, and the loss in weight due to 
 the burning or smoldering. This method of test is faulty in that 
 the wood is so finely divided that the volatile gases are readily 
 driven from it and conditions comparable to practice are not 
 duplicated. Furthermore, it is difl&cult to get concordant results 
 due to varying air currents and temperatures. 
 
 Crib Test. — So called because small splints of wood about 
 
218 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 1/2 X 1/2 X 4 inches are cut from the treated wood and piled 
 in a crib over a Bunsen burner, the flame being permitted to 
 pass through them. While better than the shaving test, the 
 method is also open to similar criticism. 
 
 Spot Test. —A flame (usually of illuminating gas) ^ is played over 
 the surface of a treated piece of wood. The depth to which it 
 charrs or burns and the character of burning or glow are noted. 
 The temperature of the flame may be read from a pyrometer, the 
 thermocouple of which is placed against the wood at point of 
 test. This method is much more comparable to practice and 
 gives good indicative results, which, however, are faulty in that 
 they are difiicult of duplication. 
 
 Electric Furnace.' — This method of test gives concordant results 
 when small pieces of wood are treated, and enables an accurate 
 comparison between various treatments. It is objectionable, 
 however, in that the heat is applied to all sides of the test speci- 
 men and usually requires that the treated plank be cut into small 
 sizes. For laboratory work, however, this method of testing has 
 been found very satisfactory. The apparatus consists of a silica 
 tube, wrapped with nichrome ribbon. An iron tube fitted with 
 a mica sight is cemented below the silica tube. 
 
 The specimen of wood, after being lowered into the silica tube, 
 is heated at a uniform rate, by passing 24 amperes of electric 
 current through the nichrome ribbon. Temperature readings are 
 obtained from a thermocouple placed beside the specimen and 
 reading direct from a Hoskins pyrometer. A pilot light is used 
 to ignite the gases distilled from the wood. Compressed air par- 
 tially dehydrated by expansion is passed through the apparatus, 
 its intensity being indicated by a sensitive liquid manometer. 
 The temperature of ignition, character of combustion or glow, 
 and loss in weight due to the burning for a 3-minute period is 
 noted. After ignition the specimen is lowered into the iron tube, 
 where it can burn of its own heat. 
 
 Cost of Rendering Wood Noncombustible.^ — The cost of ren- 
 dering wood noncombustible is in general higher than to protect it 
 from decay. As has been mentioned, most effective results in 
 fireproofing wood have been secured by injecting chemicals into 
 it. These are more corrosive than the common preservatives and 
 hence increase plant depreciation. Then, the preservatives them- 
 
 ' A plate heated electrically has been suggested in place of the flame as 
 being easier of control. 
 
THE PROTECTION OF TIMBER FROM FIRE 219 
 
 selves are comparatively expensive. Finally, the wood, after it 
 has been treated, must generally be kiln-dried to avoid loss in 
 time" and checking in seasoning. Taking the above factors into 
 consideration, the cost of rendering wood fire retardent is ap- 
 proximately as follows, when chemicals like ammonium phosphate, 
 costing about 8.5 cents, and ammonium sulphate, costing about 
 3 cents per pound, are used. 
 
 Estimated Cost of Rekdeking Wood Noncombustible Per M.B.M. 
 
 Cost of handling »2.00- $3.00 
 
 Plant depreciation and maintenance . 90- 2 . 00 
 
 Chemicals 10.00- 18.00 
 
 Kiln-drying 2.00- 4.00 
 
 Total $14.9O-$27.00 
 
 The lower figure of $14.90 per thousand assumes the plant in 
 continuous operation and the consumption of chelnicals about 175 
 pounds per M.B.M. The upper figure of $27 covers opera- 
 tions which are not continuous and allows for a heavier injection 
 of the salts into the wood. 
 
 The Efifect of Zinc Chloride and Creosote on the Inflammability 
 of Wood. — Although zinc chloride is not one of the most ef- 
 ficient fire retarding chemicals, nevertheless wood treated with 
 it is much more difficult to burn than untreated wood. This 
 makes zinc-chloride treated timber of particular value in those 
 locations where decay is rapid and danger from fire important, 
 as for example in coal mines. Timber treated with zinc chloride 
 will ordinarily ignite at the same or lower temperatures as un- 
 treated wood but will burn far more slowly. This is due in a 
 large measure to the hygroscopic nature of the salt. Some tests 
 made in the electric furnace above described at the U. S. Forest 
 Products Laboratory on zinc-chloride treated hemlock gave a 
 temperature of ignition of 287° C. as against 320° C. for untieated 
 wood. Only 19 percent of the treated wood was destroyed, how- 
 ever, as against 29 percent of natural wood. 
 
 Much discussion has occurred concerning the inflammability 
 of wood treated with coal-tar creosote. This matter was also 
 investigated at the U. S. Forest Products Laboratory and it was 
 found that wood freshly treated with creosote was very inflam- 
 mable, but that its resistance to burning increased with its age. 
 This is undoubtedly due to the lighter oils volatilizing from the 
 
220 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 wood and leaving the heavier oils. When tested under the condi- 
 tions analogous to the zinc-treated specimens mentioned above, 
 freshly creosoted hemlock ignited at a temperature of 173° C. and 
 lost 40 percent of its weight in a 3-minute burning period. When 
 a;llowed to air-season for 90 days, the temperature of ignition rose 
 to 216° C. and a loss of only 27 percent in weight occuired. Many 
 instances showing the resistance of seasoned creosoted timber to 
 fire have been repoited, of which the following are cited: 
 
 After the Jacksonville fire the creosoted telephone poles were 
 standing in good condition although the buildings all about them 
 had been destroyed. 
 
 The Stuyversant docks at the same place were built of un- 
 treated and creosoted timber. The latter was easily extinguished 
 while the former was completely destroyed. 
 
 In Baltimore the creosoted wood-block streets did not burn 
 but came through the fire better than pavements of asphalt which 
 melted and ran down the sewers. 
 
 The author saw a shaft of a coal mine in Pennsylvania which 
 had caught fire, it being timbered with untieated and creosoted 
 props. Aftei the fire was extinguished by smothering the mouth 
 of the shaft, all the untreated props had been burned to such an 
 extent as to be useless while those creosoted were simply charred 
 and not replaced. 
 
 It appears that the creosote in timber when it does ignite burns 
 for a long time in much the same manner as oil does in a wick; 
 hence the reason why the wood itself is so slightly consumed. It 
 must not be construed that creosoted timber is fire resistant in the 
 same sense that zinc-treated timber is, but that wheuv thoroughly 
 air seasoned it burns for some time with less damage to the wood 
 than untreated wood. 
 
CHAPTER XVII 
 
 THE PROTECTION OF WOOD FROM MINOR 
 DESTRUCTIVE AGENTS 
 
 A description of the manner in which these minor destructive 
 agents attack wood has been given in Chapter II. We will now 
 consider methods of protection. 
 
 Alkaline Soils. — While it is well known that certain alkalies will 
 attack wood and eventually disintegrate it, there is no positive 
 evidence which shows that their presence in the so-called "alkali 
 soils " does this. It is quite likely that the alkali is not sufficiently 
 concentrated or heated to sufficient temperature to cause disin- 
 tegration. In all cases which have been examined by the author, 
 such as deteriorated wood from flume pipes, cross-ties or poles, 
 fungus was always present. It is beheved, therefore, that if the 
 growth of the fungus is prohibited, the deterioration can be materi- 
 ally reduced or eliminated. In other words, the wood should be 
 treated for decay, the process to be selected depending upon local 
 conditions as already described. By so doing it is quite likely that 
 the effect of the alkali in the coils can be generally disregarded. 
 
 Birds. — The destruction of structural timber by birds is so small 
 as to warrant little comment, and certainly does not justify kill- 
 ing them. Woodpeckers will at times drill holes into buildings 
 and poles, and the size of the holes and the oddity of the attack has 
 given rise to an exaggerated idea of the destruction done. When 
 buildings are attacked, they are generally more or less deserted and 
 usually good for nothing but birds' nests at best. 
 
 The so-called destruction in poles is apparent rather than real, 
 as has been shown in Chapter II, although at times the holes 
 drilled by the birds may cause a real damage. No good method of 
 preventing such attacks is known. Creosoting the poles under 
 pressure is of assistance, although the birds will at times attack 
 creosoted poles. Plugging the holes is of no value as the birds 
 will drill new holes. It often appears to be a matter of "life or 
 death," and considering the great good and little real damage that 
 they do, destruction caused by birds had best be charged as an 
 
 221 
 
222 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 operating expense and borne with a smile. Nesting boxes can 
 often be used with great satisfaction, if hung on posts, poles or 
 buildings, and thus prevent damage (see Plate XXIII Fig. C). 
 The use of such boxes has been extensively tested in the Grand 
 Duchy of Hesse, where in 2 years all the boxes were inhabited. 
 
 Sap Stain.^ — ^To be efficient, all known methods of protecting 
 wood from sap stain must be applied before the stain enters 
 the wood . If the logs are stained before they are cut into 
 lumber, no satisfactory process is known for removing the stain. 
 Logs should therefore be cut as soon as possible after they are 
 felled, particularly during warm weather. 
 
 The most effective means of preventing stain is to kiln dry 
 the lumber immediately after it has been sawed, and then keep 
 it under cover. In this manner, stain can be entirely prevented. 
 This method, however, is generally too expensive and cumbersome 
 for all but the best grades of lumber. 
 
 For rough lumber, dipping in a solution of bicarbonate of 
 soda gives best commercial results. In practice, this is done by 
 having the freshly cut boards cairied through a tank of the soda 
 solution on their way to the sorting table. In this manner no 
 extra expense for handling is required. A 5 to 8 percent 
 solution is usually sufficiently strong. • This should be kept warm 
 by means of a steam coil in the bottom of the tank, which can be 
 constructed of wood, iron or concrete. A few companies are. now 
 maufacturing "soda-dipping" tanks and will furnish a complete 
 outfit (see Plate XXII, Fig. A) or the tanks can be constructed by 
 an ordinary mechanic. After the lumber has been dipped in this 
 manner, it should be piled with open air courses so that it will dry 
 rapidly. 
 
 An extended series of tests were made by the United States 
 Forest Service in co-operation with the Great Southern Lumber 
 Company at Bogalusa, La., in which pine boards were dipped in a 
 variety of solutions. It was found that solutions of mercuric 
 chloride, varying in strength from about 0.2 to 0.3 percent, were 
 most effective in preventing stain, but on account of theii very 
 poisonous nature, cannot be generally recoitrimended. 
 
 The following conclusions are drawn from these tests i^ 
 
 1. Freshly cut sap lumber when stacked in the yard to dry 
 should be stacked in open piles to permit a free circulation of air. 
 Boards so piled season in about half the time required for those 
 
 ' Circular 192 United States Forest Service. 
 
PROTECTION OF WOOD FROM DESTRUCTIVE AGENTS 223 
 
 piled in close piles. Open piles, moreover, are not so severely 
 attacked by insects and are more effectively protected against 
 sap stain. 
 
 2. In commercial work sap stain can be most effectively 
 prevented by dipping boards in solutions of sodium bicarbonate. 
 Such solutions, though they give fairly good results, leave much 
 to be desired. The strength of the solution should be determined 
 by the severity of the conditions under which the boards are 
 to season, but in general it will require from 5 to 10 percent. 
 Care should be taken that the chemical used is not mixed with 
 adulterants. 
 
 3. The best results in preventing sap stain were secured with 
 mercuric chloride solutions, but on account of their poisonous 
 nature they are not recommended for general use. 
 
 4. The solution made by mixing sodium carbonate and lime 
 was not as effective as one of sodium bicarbonate alone. More- 
 over, it had a greater tendency to streak the surface of the boards 
 with a white precipitate. 
 
 5. Solutions of magnesium chloride, calcium chloride, sodium 
 hydroxide, phenol, copper sulphate, and zinc chloride did not 
 prevent sap stain; nor did sprinkling the boards with naphthalene 
 flakes give satisfactory results. 
 
 6. On account of cheapness and facility in operation, it is 
 recommended that sap-stain solutions be apphed to the boards 
 by machinery. If this is done, the cost of treating lumber with 
 solutions of sodium bicarbonate will amount to from about 7 to 
 10 cents per 1000 board feet. 
 
 7. The indications are that shavings planed from soda-dipped 
 boards do not burn as readily as those from untreated boards, 
 but the difference in inflammability is so slight that for com- 
 mercial purposes it may be neglected. 
 
 Sand Storms. — The destruction of timber in the United States 
 by sand storms is insignificant. Far more is destroyed by wind 
 and sleet storms against which there is, of course, no known 
 method of protection except heavier and more expensive construc- 
 tion. In certain portions of the Southwest the wind carrying 
 sand at high velocity so wears away poles, stakes and posts that 
 renewal is sometimes necessary. (See Plate XXII, Fig. B.) About 
 the only practical method known of retarding such damage is to 
 nail planks of wood or sheets of metal to the poles and posts and 
 after these have been destroyed, replacing them.- 
 
CHAPTER XVIII 
 
 THE STRENGTH AND ELECTROLYSIS OF TREATED 
 
 TIMBER 
 
 The Effect of Air Seasoning on the Strength of Wood. — It 
 
 has been stated in Chapter IV that a considerable amount of 
 water can be removed from green wood, without affecting its 
 strength. As soon, however, as the water begins to leave the 
 cell walls so that their moisture content is decreased, the strength 
 of the wood rapidly increases. This is shown in Fig. 109 where 
 the strength of wood is plotted against the amount of water 
 it contains. Prolonged air seasoning removes a certain amount 
 of water from the cell walls and hence increases the strength of 
 wood. The amount of water thus removed depends upon the 
 temperature and humidity of the surrounding air and the size 
 and kind of wood being seasoned. For example, it is greatest 
 in warm dry air (as in summer) and in thin boards (1 inch or less 
 in thickness). Material, of this kind is called "air dry or sea- 
 soned" when it contains about 8 to 12 percent of water. If dried 
 to lower moisture than this it is very probable that the wood will 
 re-absorb moisture. Air-dry lumber containing 8 to 12 percent 
 of moisture is therefore seasoned about 16 to 20 percent below 
 its fiber-saturation point and has about twice the strength of green 
 wood. On the other hand if the boards are larger, say 6 to 10 
 inches in thickness it is very likely their "air-dry" moisture will be 
 15 to 20 percent rather than 8 to 12 percent. Consequently 
 their strength will not be increased to the same degree. It is 
 evident, therefore, that the term "air dry" is a very variable and 
 arbitrary one. If now, the wood is dried in a kiln and its moisture 
 reduced to say 2 to 3 percent, its strength will be increased con- 
 siderably over what it was in an air-dry condition. Thus, other 
 things being equal, the more moisture there is removed from 
 wood, the greater will be its strength (Fig. 25). This relation 
 has been equated by Tiemann^ for longleaf pine with the following 
 formula : 
 
 ' BuUetin 70, United States Forest Service. 
 
 224 
 
Plate XXII 
 
 Fig. a. — Type of soda dipping tank manufactured by the Lufkin Foundry 
 
 and Machine Co. 
 
 Fig. .B. — Stake damaged by sand storms in southern California. Com- 
 pare portion in the ground with portion above ground. (Photo courtesy 
 of the Am. Tel. & Tel. Co.) 
 
 (Facing page 224.) 
 
Plate XXII 
 
 Fig. C. — Section of an experimental track laid with steel ties. (Photo 
 courtesy of the Ry. Eng. Ass'n.) 
 
 Fig. D. — A fence of concrete posts, Madison, Wis, (Photo courtesy Na- 
 tional Concrete Machinery Co.) 
 
THE STRENGTH OF TREATED TIMBER 
 
 225 
 
 C = G (22.1 P" - 1335 P + 25,610) 
 where C = crushing strength in pounds per square inch 
 
 G = specific gravity of dry wood 
 
 P = percent of moisture. 
 On account of the wide variability in the structure of wood, the 
 equation is applicable only within certain limits, and will not, of 
 course, give the exact strength for each and every piece of wood, 
 but is sufficiently close for most commercial engineering problems. 
 
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 1.000 
 
 900 
 
 5 10 15 20 25 30 35 40 45 SO 5S 60 65 70 
 Moistare-Per cent of Dry "Weight 
 
 Fig. 25. — Moisture-strength curves for longleaf pine, eastern spruce and 
 chestnut. Note fiber-saturation points. 
 
 Lowering the moisture content of wood below its fiber-satura- 
 tion point produces certain phenomeiia; the more important, so 
 far as strength is concerned, being shrinkage and cell slitting. 
 Both of these vary with the kind of wood, the degree to which 
 it is seasoned, and the manner in which it is seasoned. Conifers 
 
 shrink less than hardwoods, and the drier the wood the greater 
 la 
 
226 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 the shrinkage. Given the specific gravity of a piece of wood 
 its shrinkage from a green to oven-dry condition can be fairly 
 closely approximated from the following logarithmic equations 
 developed by J. A. Newlin: 
 
 Shrinkage in volume percent = 26.5 G' "'' 
 
 Radial shrinkage in percent = 9.5 G'"° 
 
 Tangential shrinkage in percent = 16.5 G^ '"' 
 where G = specific gravity. 
 
 When water leaves the cell walls it sometimes happens that 
 these check open and become more or less filled with microscopic 
 slits (Fig. 24) . These slits apparently weaken the wood but their 
 weakening effect by no means offsets the marked increase in 
 the strength of the wood due to its loss of water. If wood which 
 has once been thoroughly air- dried is resoaked in water until it 
 contains as much water as it originally had, its strength will be 
 found to be less than the original green strength. The slitting of 
 the walls probably has much to do with this. 
 
 From the above discussion, it can readily be seen that any 
 treating process which tends to keep wood dry will, provided it 
 does not in itself weaken the wood, tend to increase the strength 
 of the wood. Thus treatments with creosote tend to retard the 
 absorption of water and hence keep the wood in a stronger and 
 more resilient condition than untreated wood or wood treated 
 with a preservative like zinc chloride. This is of decided ad- 
 vantage in certain cases, as in paving blocks, and is undoubtedly 
 one reason why creosoted blocks have resisted wear so much 
 better than similar blocks laid untreated. On the other hand, 
 objections have been raised to the seasoning of wood, partic- 
 ularly in mines, where certain operators assert that they prefer 
 green wood to dry or partially dry as it bends more and gives 
 better warning of danger from rock fall. 
 
 The Effect of Steaming on the Strength of Wood. — ^Little is 
 known concerning the effect of superheated steam on the strength 
 of wood, but from our knowledge of the effect of temperature on 
 wood, the rapid drying of wood and practical operative results 
 with superheated steam, it appears that it is very prone to 
 seriously weaken wood and render it brash and brittle. 
 
 Saturated steam is in common use in preparing wood for treat- 
 ment as has been shown in previous chapters. Saturated steam 
 in itself does not dry wood, but heats it so that drying is possible. 
 In fact, while the wood is in the steam it may actually take up 
 
THE STRENGTH OF TREATED TIMBER 227 
 
 water, particularly if it is already partially seasoned. This is 
 shown in the following table: 
 
 Table 34. — Increase in Weight of Loblolly-pine Ties Due to 
 
 Steaming* 
 
 Conditions of steaming 
 
 Gain in weight per tie, due to steaming | 
 
 Period 
 
 Pressure per square 
 inch 
 
 Green ties 
 
 Air-seasoned 
 ties 
 
 Hours 
 4 
 4 
 4 
 4 
 4 
 6 
 10 
 
 Pounds 
 10 
 20 
 30 
 40 
 50 
 20 
 20 
 
 Pounds 
 2.13 
 
 Pounds 
 5.1 
 6.9 
 6.3 
 8.1 
 4.3 
 10.8 
 10.7 
 
 0.62 
 1.12 
 0.62 
 
 1.00 
 
 After the wood has been heated and the steam around it removed, 
 the heat units stored in the wood will evaporate much of the 
 water it contains and produce a condition of partial dryness 
 or "seasoning." A vacuum applied immediately after the steam 
 bath will further increase the drying, since it lowers the tem- 
 perature at which the water will vaporize. Common practice, 
 therefore, is to steam the wood and then apply a vacuum. The 
 important items to consider, in so far as the effect of steaming 
 on the strength of wood is concerned, are the temperature of the 
 steam and the length of time it is appUed to the wood. The best 
 data on this subject known to the author is contained in United 
 States Forest Service circular 39, which summarizes the results 
 of about 6000 tests. Due to the variability of the wood used 
 and the complexity of the problems, it is probable that further 
 tests might change some of the conclusions there drawn, but the 
 essential features are probably correct. In general, it appears 
 from these tests that steaming at high temperatures, or lower 
 temperatures for long periods, materially weakens the strength 
 of wood. The extent of the weakening will depend upon the kind 
 of wood, its moisture content at the time of seasoning, the 
 character of the wood structure such as density, rate of growth, 
 etc., and the manner in which the steam is applied. Disregarding 
 the individual effect of each of these, and lumping them all 
 together, the effect of the temperature of the steam and the 
 length of time it is applied is shown in Table 35.^ 
 
 1 Circular 39, United States Forest Service. 
 "United States Forest Service Circular 39. 
 
228 THE PRESERVATION OF STRUCTURAL TIMBER 
 
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THE STRENGTH OF TREATED TIMBER 229 
 
 In this table the word "control" refers to the test pieces cut from 
 the ends of the ties which were left untreated in order to furnish a 
 standard of comparison. It should be noted that these pieces 
 were tested immediately after treatment. It was found that if 
 they were air seasoned after treatment and then tested they 
 regained a large part of their original strength. Sufficient reliable 
 data is not available to state accurately what is the maximum 
 temperature of steaming or maximum duration of steaming that 
 should be used. The conclusion drawn from the tests just quoted 
 was that "for loblolly pine the limit of safety is certainly 30 
 pounds for 4 hours, or 20 pounds for 6 hours." It is well known 
 that some of the best results secured in the treatment of wood in 
 this country have been obtained from timbers (longleaf pine 
 piling) which were steamed at higher temperatures and longer 
 periods than this, hence it is entirely probable, when full informa- 
 tion is available, that more severe steaming treatments will be 
 found safe and practicable. 
 
 The Effect of Boiling Wood in Creosote upon its Strength. — ■ 
 If wood is submerged in creosote which is heated above the 
 boihng point of water under atmospheric pressure only, the water 
 contained in the wood will be converted into steam. Unless 
 confined, the steam will escape and thus the water content of the 
 wood will be reduced. It is obvious, therefore, that boihng wood 
 in creosote seasons the wood and is quite a different action from 
 steaming wood, which as already described, is simply a means of 
 heating it. If, however, the wood is heated in oil under pressure, 
 the action should be similar to that produced by steaming it, 
 since the pressure will prevent the water from vaporizing. 
 
 It is well known that rapidly seasoning timber is very apt to 
 weaken it, because it tends to develop checks and slits. This is 
 particularly true of woods having a complex structure such as 
 the oaks, maples, etc. Without definite knowledge we should 
 therefore expect to find a decrease in the strength of wood boiled 
 in creosote, particularly if the boiling reduces the moisture in the 
 wood much below its fiber-saturation point. Information on 
 this point is meager. Some green Douglas fir bridge stringers 
 boiled in creosote and then impregnated with the oil showed 
 about 40 percent loss in strength over similar stringers untreated. 
 This decrease was, apparently, permanent, because a year's 
 seasoning after treatment showed approximately the same 
 results. One example does not, of course, prove that the 
 
230 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 weakening was caused by the boiling, as it may have been due 
 either to the heat or the oil. The shrinkage of timber boiled 
 in oil is very rapid and its quite possible that this rapid shrinkage 
 may produce injury by setting iip a complex series of stresses in 
 the wood. Whether or not this is the case and the extent to 
 which it may affect the various woods is not known at the 
 present writing. 
 
 The Effect of Preservatives on the Strength of Wood. — This 
 is a much discussed problem on which little conclusive data is 
 available. A number of tests have, however, been made and 
 from them certain deductions can be drawn. The preservatives 
 which have been tested are creosote, zinc chloride, and crude oil. 
 
 Creosote. — It has commonly been supposed that creosote does 
 not enter the cell walls of wood and for this reason could have, 
 per se, little or no effect on the strength of wood. Careful tests 
 by Teesdale^ have shown that creosote enters the cell walls and 
 will cause them to swell. The amount which is absorbed by the 
 walls in practice is, however, insignificant compared with the 
 total amount injected. We should expect, therefore, that 
 creosote has but little weakening effect on the strength of wood 
 treated with it. Tests made on creosoted wood, tend to sub- 
 staotitate this (Table 6), these being made on small clear speci- 
 mens impregnated with about 8 pounds of oil per cubic foot. Green 
 loblolly pine steamed and creosoted with about 20 pounds of oil 
 per cubic foot showed no loss in strength over the ties which were 
 simply steamed and then tested. In fact, in creosoting loblolly 
 pine without steaming, the creosoted wood tested higher than 
 the untreated wood, the process apparently having a tendency 
 to dry the wood.^ Some full-sized longleaf pine bridge stringers 
 steamed, creosoted by the Bethel process with 12 pounds of oil per 
 cubic foot and then tested, showed no apparent loss in strength 
 over the stringers tested untreated and carefully matched with 
 them. It appears that when the wood is not damaged by the 
 process, creosote in' itself will produce little or no weakening of 
 practical significance. There is, however, a possibility that 
 this will not hold for all kinds of wood but at present data to 
 substantiate this is not known. 
 
 Zinc Chloride. — It is well known that a concentrated solution 
 of zinc chloride will dissolve wood. In practice, the solutions 
 
 1 Circular 200, United States Forest Service. 
 ^ Circular 39, United States Forest Service. 
 
THE STRENGTH OF TREATED TIMBER 231 
 
 rarely exceed a strength of 6 percent and at this concentration 
 their action on wood is very sUght. The common specification 
 calls for an injection of a half pound of dry zinc chloride per cubic 
 foot of wood. Assume the wood after treatment will season to 
 10 pounds of water per cubic foot and the preservative has been 
 diffused through it. This will give a strength of only 5 percent. 
 If, however, the solution only penetrates the outer fibers of the 
 wood and the zinc chloride concentrates itself in these fibers, 
 it may reach sufficient strength to do actual harm. In this 
 condition the wood is said to be "burnt" or "killed" and is in- 
 variably the result of poor workmanship. Proper treatments 
 use as weak solutions as possible in order to get the requisite 
 absorption, and thus avoid any liabiUty to injury of the wood 
 fiber. Green loblolly pine treated with zinc chloride solutions 
 of various concentrations and then tested in static bending, 
 compression parallel to the grain and in impact bending, gave 
 the following results when air dried to about 13 percent moisture.^ 
 
 strength of Average strength in 
 
 solution percent of steamed wood 
 
 2.5 98.0 
 
 3.6 95.1 
 
 5.0 91.8 
 
 10.0 91.8 
 
 The conclusions drawn from these and similar tests is that zinc 
 chloride when properly injected into wood will not weaken it to 
 any appreciable extent under static loading, but apparently tends 
 to render it brittle under impact, especially when strong concen- 
 trations are used. 
 
 Crude Oil. — Crude oil when heavily injected into wood ap- 
 parently weakens it. Thus some loblolly pine, shortleaf pine 
 and red gum ties, impregnated with about 14 pounds of crude oil 
 per cubic foot, gave only 73, 72, and 90 percent respectively of 
 the strength of the same kind of ties untreated, whereas the ties 
 treated with creosote and zinc chloride showed no loss whatever. 
 
 The Efifect of Temperature on the Strength of Wood. — Heat 
 tends to weaken wood, cold to stiffen it. In this respect wood, 
 therefore, behaves hke a plastic material. Tiemann^ has made 
 some careful researches along these fines, and the results secured 
 by him have been substantiated by further tests. He has soaked 
 
 ' Circular 39, United States Forest Service. 
 ' BuUetia 70, United States Forest Service. 
 
232 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 pieces of longleaf pine, spruce and chestnut in water for various 
 periods and then tested them at various temperatures. The 
 general results are shown in Table 36. The tests designated 
 "cold" were made when the wood was at temperatures ranging 
 from 7° to 19° F.; those marked "warm" at 45° to 68° F. An 
 examination of all the results shows a decided increase in both 
 the strength and stiffness of the frozen pieces, excepting the 
 very dry wood. Of course, in treating operations the timber 
 is seldom frozen, although this at times occurs. On the other 
 hand, the temperatures in the cylinder frequently rise to 250° 
 F. It is doubtful whether this is sufficiently high to cause in itself 
 any permanent weakening in the wood, so that after the timber 
 has again reached atmospheric temperature no weakening due 
 to the temperature of treatment has any practical significance". 
 
 Table 36. — The Effect of Temperature on the Strength of Wood 
 
 (Specimens about 2 X 2 X 5.75 inches'* 
 
 Kind of wood 
 
 How 
 tested 
 
 Moisture at 
 test, percent 
 
 Crushing strength, 
 lb. per sq. in. 
 
 Modulus of elasticity, 
 lb. per sq. in. 
 
 Longleaf pine. 
 
 cold 
 warm 
 
 23 
 
 24 
 
 6,440 
 5,750 
 
 1,418,000 
 1,360,000 
 
 Spruce 
 
 cold 
 warm 
 
 27 
 22 
 
 4,060 
 3,923 
 
 894,000 
 753,000 
 
 Chestnut 
 
 cold 
 warm 
 
 68 
 72 
 
 3,180 
 2,622 
 
 708,000 
 553,000 
 
 THE EFFECT OF PRESSURE ON THE STRENGTH OF WOOD 
 
 Pressures used in treating timber are all far too low to cause 
 any weakening of the wood. A pressure of 200 pounds per square 
 inch is about as high as is ever held and even this is much below 
 the crushing strength of our weakest commercial woods. It is 
 quite probable that the wood during treatment undergoes a 
 shght decrease in volume (less than 0.5 percent in general woods) 
 due to the pressure used, but that on the release of pressure this 
 is fully recovered. 
 
 The Effect of Various Treatments on the Strength of Wood. — 
 We have now considered the individual effect of the various units 
 in the treatment of timber upon the strength of the timber. Let 
 us now consider their combined effect as shown by some tests on 
 treated wood. For this information we are indebted to Dr. W. K. 
 
THE STRENGTH OF TREATED TIMBER 
 
 233 
 
 Hatt, who tested a number of ties treated by various processes at 
 commercial plants . In other words, no attempt was made to study- 
 more than the added effect of all factors entering into the treat- 
 ment in order to ascertain whether or not the treatment decreased 
 the strength of the ties over similar ties untreated. The results 
 of these tests are shown in Table 37. 
 
 Table 37. — Showing Effect of Teeating Ties upon Their Cbushing 
 Strength and Spike Holding Power' 
 
 Kind of wood 
 
 Treating 
 process used 
 
 Crushing 
 strength at 
 elastic limit 
 
 perpendicular 
 to grain in 
 
 percent of un- 
 treated tie 
 
 Resistance to spike pulling 
 
 in percent of untreated 
 
 tie with cut spikes 
 
 Cut spikes 
 
 Screw spikes 
 
 Red oak 
 
 Loblolly pine 
 
 Shortleaf pine.... 
 Longleaf pine. . . . 
 Red gum 
 
 Untreated. . . 
 Burnettized. 
 
 Lowry 
 
 Rueping 
 
 Full cell.... 
 
 Untreated. . . 
 
 Rueping 
 
 Lowry 
 
 Rueping 
 
 Full cell.... 
 Crude oil... . 
 
 Untreated. . . 
 
 Rueping 
 
 Full cell.... 
 Crude oil... . 
 
 Untreated. . . 
 
 Rueping 
 
 Full cell .... 
 
 Untreated. . . 
 
 Rueping 
 
 ' Full cell.... 
 Crude oil. . . . 
 
 100 
 97 
 
 104 
 92 
 
 104 
 
 100 
 99 
 104 
 112 
 100 
 73 
 
 100 
 
 103 
 
 108 
 
 72 
 
 100 
 109 
 101 
 
 100 
 97 
 99 
 90 
 
 100 
 98 
 93 
 93 
 
 101 
 
 100 
 
 123 
 
 94 
 
 109 
 
 84 
 
 53 
 
 100 
 
 100 
 
 103 
 
 45 
 
 100 
 100 
 105 
 
 100 
 
 102 
 
 105 
 
 70 
 
 173 
 172 
 163 
 162 
 172 
 
 215 
 209 
 219 
 246 
 184 
 192 
 
 241 
 209 
 223 
 176 
 
 202 
 205 
 270 
 
 228 
 222 
 252 
 270 
 
 ' A part of the differences in strength here noted are due to varying 
 moisture contents of the ties and the fact that different ties had, of course, 
 to be used, it being impossible to keep these absolutely uniform. 
 
 Data taken from experiments made under the direction of Dr. W.K. 
 Hatt and published in the bulletins of the American Railway Engineering 
 Association. 
 
234 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 It'^will be noted that all the treatments show httle or no decrease 
 in strength with the exception of crude oil. The increases noted 
 may be due to superior wood in the treated ties or to their having 
 dried out more than the untreated ties or to a combination of these 
 two. Of course, all these conclusions presuppose that the treat- 
 ments were properly made and are normal. Bad management on 
 the part of the treating engineers would, undoubtedly, have 
 yielded entirely different results. 
 
 The Electrical Resistance of Wood Treated with Creosote and 
 Zinc Chloride. — This a matter of considerable importance to 
 steam railroad companies in the operation of their block signals, to 
 electric traction companies in the return of their current, and to 
 telephone and hydro-electric companies in the seepage of current 
 carried in wires over their poles. As is usual in problems of 
 this kind, the opinions of operating men vary considerably, and 
 httle agreement is found. Mr. J. T. Butterfield conducted some 
 interesting and valuable experiments on this problem at Purdue 
 University in 1910, with ties treated at commercial plants, the 
 following information being taken from his work: 
 
 "The resistance was measured by the method commonly used 
 for measuring the insulation resistance of electrical machinery, 
 namely, by means of a direct-current voltmeter of known resist- 
 ance. This method was applied in two ways. (1) The contact 
 surface for flow of current in the ties was a sawn surface as nearly 
 plane as possible. Contact pressure of 250 pounds per square 
 inch was appUed in a Riehle Testing Machine by means of sheet- 
 iron pans, placed one above the other and filled between with 
 dry sand, by which constant surface resistance was obtained. 
 (2) After some of the fundamental laws were investigated, the 
 resistance of the various ties was compared by measuring the cur- 
 rent flowing between two spikes driven 20 inches apart in the 
 face of each tie. Then the relation of these latter tests, between 
 the two spikes, to the conditions obtaining in a full tie with 
 rails spiked thereto was investigated. 
 
 In beginning the tests the principal elements which cause the 
 resistance to vary were determined and investigated in the follow- 
 ing order: 
 
 1. Amount of moisture present. 
 
 2. Kind of wood. 
 
 3. Treatment. 
 
 4. Direction of grain. 
 
THE STRENGTH OF TREATED TIMBER 235 
 
 5. Contact pressure 
 
 6. Temperature. 
 
 7. Amount and time of current flowing. 
 
 8. Dimensions of specimen. 
 
 Moisture. — The important effect of moisture is plainly shown 
 by the following tables, determined by the testing-machine 
 method : 
 
 
 Test 
 
 OF 
 
 Red 
 
 Oak 
 
 Zinc-chloride treatment 
 it moisture 
 14.4 
 17. 
 
 1.7 percent 
 
 Ohms per cu. 
 
 3,370,000 
 414,000 
 
 19.1 
 
 27.4 
 
 
 
 
 94,000 
 2,140 
 
 35.7 
 
 
 
 
 1,381 
 
 47. 
 52.2 
 
 13.3 
 17.3 
 
 
 Untreated 
 
 1,310 
 1,100 
 
 5,020,000 
 784,000 
 
 21.6 
 
 
 
 
 198,000 
 
 26.6 
 
 
 
 
 136,300 
 
 38.0 
 43.3 
 
 
 
 
 7,100 
 6,440 
 
 47.3 
 
 
 
 
 5,070 
 
 In order to investigate the longitudinal distribution of resistance 
 through a tie, a number were cut up into 6-inch lengths and the 
 resistance measured parallel with the grain. The results plainly 
 showed that there was an enormous resistance at the ends of a 
 tie, which may have a uniformly low resistance in the interior. 
 The cause for this high-end resistance was, of course, the drying 
 out of the ends. / 
 
 KIND OF WOOD AND TREATMENT 
 
 In measuring the resistance of different woods, the method 
 used was that of determining the resistance between two spikes, 
 as described above. The ties were generally tested in the yard 
 and had been piled. Some were covered and were no doubt less 
 dry than others. Variation in resistance of untreated ties of 
 same species is to be accredited to moisture variation. Generally 
 tests of 5 treated and 15 natural ties enter into the average. 
 
236 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 LOWRY CBBOSbTE PROCESS 
 
 Resistance Ratio of, 
 
 (megohms per half tie) treated to 
 
 Natural Treated natural 
 
 Red oak 0.182 0.177 0.973 
 
 RuEPiNG Process 
 
 Loblolly pine 5.68 5.05 0.91 
 
 Shortl^af pine 2.97 1.035 0.35 
 
 Longleaf pine (very dry) 5.4 6 . 05 1 . 12 
 
 Red gum 0.39 0.22 0.68 
 
 Loblolly pine 1.46 1.41 0.96 
 
 Full-cell Process 
 
 Loblolly pine 2 . 94 1 . 00 . 34 
 
 Shortleaf pine 3.41 2.70 0.79 
 
 Longleaf pine 1 . 80 2.2 1 . 22 
 
 Red gum 0.225 0.28 1.24 
 
 Loblolly pine 4.47 0.905 0.20 
 
 Zinc Chloride Process 
 
 Red oak 0.08 0.0125 0.156 
 
 DIRECTION OF GRAIN 
 
 The direction of the grain has a decided effect upon the 
 resistance of wood, and as the resistance of ties was taken parallel 
 with the grain, little consideration was given the question aside 
 from the following tests: 
 
 Resistance in Megohms 
 
 Kind of wood 
 
 
 Radial to 
 
 Tangential 
 
 
 3-in. cubes, 
 
 Lengthwise 
 
 growth 
 
 to growth 
 
 
 air dried 
 
 
 rings 
 
 rings 
 
 
 Natural red oak 
 
 0.0175 
 
 0.12 
 
 0.15 
 
 26 
 
 Natural red oak 
 
 0.0175 
 
 0.041 
 
 0.07 
 
 40 
 
 CONTACT PRESSURE 
 
 The study of the effect of contact pressure on a number of 
 different specimens held between contacts in the testing machine 
 and involving the longitudinal resistance corresponding to 
 different loads developed the following results. As would be 
 expected, it was found that the resistance decreases rapidly with 
 increase of contact pressure. 
 
THE STRENGTH OF TREATED TIMBER 237 
 
 Red Oak, Zinc Chloride Treatment, 3-in. Cubes 
 
 Lengthwise of grain Air dried 
 Lb. per 
 
 sq. in. O^""^ 
 
 500.0 175 
 
 278.0 180 
 
 56.5 220 
 
 22.2 270 
 8.9 460 
 3.3 575 
 1.0 1550 
 0.0 5850 
 
 Red Gum, Natural, 3-in. Cubes 
 
 Lengthwise of grain Air dried 
 
 55.5 26,400 
 
 33.3 26,800 
 22.2 27,700 
 15.5 30,350 
 11.0 32,700 
 
 7.9 33,000 
 
 5.5 39,400 
 
 0.0 67,000 
 
 TEMPERATURE 
 
 Some preliminary tests were made upon the ties to discover 
 the effects of temperature. The results, although not capable 
 of representation by a smooth curve, showed that the resistance 
 decreased with an increase of temperature in a nearly direct 
 proportion. 
 
 Red Oak 
 
 Zinc chloride treatment — testing machine method. End of grain 
 
 Block =5X8X6 mch 
 
 Temperature = average of six thermometers 
 
 Temperature, Resistance, 
 
 degrees C. ohms 
 
 0.33 2500 
 
 3.65 2100 
 
 5.70 1945 
 
 7.50 1820 
 
 10.70 1560 
 
 12.20 1270 
 
 14.50 1050 
 
 16.70 910 
 
 21.00 670 
 
 22.50 623 
 
238 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 ELECTROLYTIC EFFECT 
 
 While measuring a low resistance in the testing machine with 
 a high voltage it was noticed that the voltmeter needle tended 
 to fall back rapidly if the circuit was allowed to remain closed 
 for a short time. This pointed to some kind of an electrolytic 
 effect, and some tests were therefore made in which the current 
 was allowed to flow for some time until the resistance became 
 nearly constant. Then the circuit was opened and the specimen 
 allowed to recover. The following are the results: 
 
 
 Electrolytic Effect 
 
 
 
 Natural red oak. 60 percent moisture 
 
 
 Time 
 
 Volts 
 
 Ohms per 
 cu. in. 
 
 0.00 sec. 
 
 13.00 
 
 1010 
 
 0.15 sec 
 
 12.80 
 
 1130 
 
 0.30 sec. 
 
 12.70 
 
 1190 
 
 1 . 00 min. 
 
 12.61 
 
 1248 
 
 2 . 00 min. 
 
 12.55 
 
 1288 
 
 3 . 00 min. 
 
 12.50 
 
 1320 
 
 4.00 min. 
 
 12.47 
 
 1340 
 
 6.00 min. 
 
 12.41 
 
 Circuit opened 
 
 1380 
 
 7 . 00 min. 
 
 12.40 
 
 1386 
 
 8 . 00 min. 
 
 12.79 
 
 1140 
 
 9 . 00 min. 
 
 12.86 
 
 1101 
 
 0.00 min. 
 
 12.92 
 
 1056 
 
 1.00 min. 
 
 12.92 
 
 1056 
 
 INFLUENCE OF VOLUME 
 
 The relation of resistance to the dimensions of the specimen 
 was .plainly showed to vary the sajne as with any conducting 
 material. 
 
 Red Oak — Zinc Chlobide Treatment 
 
 Length Section Resistance, 
 
 ohms 
 
 6 in. 3 sq. in. 9,790 
 
 9 in. 3 sq. in. 16,030 
 
 12 in. 3 sq. in. 22,500 
 
 15 in. 3 sq. in. 35,500 
 
 Red Oak — Natural 
 
 Length 3 in. Cross section varied 
 
 Cross section, sq. in. Resistance, ohms 
 
 9 6,000 
 
 18 11,000 
 
 27 16,000 
 
 36 22,000 
 
THE STRENGTH OF TREATED TIMBER 239 
 
 RELATION OF TESTS BETWEEN SPIKES TO ACTUAL TIE 
 
 A few tests were made with rails spiked to a whole tie, and the 
 resistance measured and compared to the resistance of spikes 
 20 inches apart. 
 
 The resistance between the rails spiked to the whole tie was 
 found to be about 18 times the resistance between spikes 
 driven 20 inches apart and 4 1/2 inches in the face of the tie. 
 
 The moisture condition of the surface of the tie was artificially 
 varied. 
 
 H = The percentage increase in conductivity between rail and 
 tie, due to rail bearing. For example, the value of H = 0.95 
 for oak ties is found as follows : 
 
 44400 44800 
 H = , ^^ X 100 = 0.95 percent. 
 
 44800 
 
 CONDUCTIVITY OF TIE WITH RAILS SPIKED THERETO AS COM- 
 PARED WITH SPIKES ALONE 
 
 Section of 85-pound Rail Spiked to Ties at Standard Gage Distance. No. 
 6 is Red Oak. No. 7 is chestnut 
 Condition of tie 
 
 Dry; spikes only ( No. 6 
 
 I No. 7 
 Dry; with rails f No. 6. 
 
 No. 7. 
 Wet at rail bearing; spikes only / No. 6. 
 
 I No. 7. 
 Wet at rail bearing; with rails ( No. 6. 
 
 I No. 7. 
 Wet all over; with rails / No. 6. 
 
 1 No. 7. 
 Bottom of tie in wet gravel; with rail. . . . No. 6. 
 
 Tie in moist gravel ballast; with rail No. 7. 
 
 Tie in very wet ballast; with rail f No. 6. 
 
 I No. 7. 
 Same as above; spikes only f No. 6. 
 
 I No. 7. 
 
 The resistance of the bearing between a newly spiked dry rail 
 and a dry red-oak tie will be found to be approximately 1 per- 
 cent of the total conductivity of the tie, but after the spikes 
 have loosened the pressure on the rail bearing is about the 
 
 Ohms. H. 
 
 Percent. 
 
 44,800 
 
 0.95 
 
 9,500 
 
 2 
 
 16 
 
 44,400 
 
 
 
 ',9,300 
 
 
 
 43,700 
 
 
 
 93 
 
 9,400 
 
 6 
 
 79 
 
 43,300 
 
 
 
 8,800 
 
 
 
 27,800 
 
 
 
 7,760 
 
 
 
 10,270 
 
 
 
 4,350 
 
 
 
 6,780 
 
 7 
 
 68 
 
 3,220 
 
 6 
 
 52 
 
 7,300 
 
 
 
 3,430 
 
 
 
240 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 weight of rail per tie divided by the area of the bearing. This 
 is about 2 pounds per square inch. Such light pressure means 
 high contact resistance. Considering the further fact that the 
 crosswise resistance of a tie is several times its lengthwise 
 resistance per unit of length, and that all leakage current through 
 the rail bearing must pass through a considerable amount of 
 cross-grain resistance, the total resistance of the leakage path 
 between rails is very high. 
 
 CONCLUSIONS 
 
 The results obtained tend to establish the following conclusions: 
 Timber is ordinarily classed with the nonconductors. When 
 dry and well seasoned, it has a very high dielectric strength and 
 practically infinite resistance. When green or moist, however, 
 timber becomes a kind of electrolytic conductor of comparatively 
 low resistance. The treatment with zinc preservatives has the 
 simple effect of producing in the wood a stronger electrolyte and 
 hence a better conductor of current. 
 
 1. The resistance of timber varies directly with the length 
 and inversely with the cross section. 
 
 2. The resistance of timber varies almost inversely with the 
 amount of moisture present, between the limits of 15 and 50 
 percent. 
 
 3. The resistance of timber is lowest when measured along 
 the grain, and highest when measured tangentially to the growth 
 rings. 
 
 4. When treated with a soluble salt such as zinc chloride, 
 the resistance varies approximately inversely as the amount of 
 the salt present. 
 
 5. Treatment with such a soluble salt does not change the 
 behavior of the resistance with respect to the percent moisture 
 present. Only the amount of the resistance is changed. 
 
 6. The resistance of timber varies almost inversely with the 
 temperature between the limits of zero and 50° C. 
 
 7. The resistance of nonporous woods, such as the pines, 
 is higher than that of porous woods, such as the oaks and red 
 gum. 
 
 8. Treatment of timber by different creosote processes does 
 not greatly change the natural resistance of the timber. 
 
 9. Finally, all the data taken goes to establish the view that 
 
THE STRENGTH OF TREATED TIMBER 241 
 
 the conductivity of wood is due primarily to the presence in the 
 pores of an electrolyte formed by an aqueous solution of the 
 salts found in the natuial timber, or of these salts and others 
 artificially introduced. 
 
 Assuming the worst condition for leakage covered by the test, 
 i.e., red oak ties treated with zinc chloride laid in wet ballast 
 and with wet rail bearings, the resistance between the rails of a 
 block 1 mile in length would approximate 30 ohms. This 
 would permit a leakage current of 0.05 ampere to flow with the 
 battery voltage of 1.5 volts. The leakage loss would, there- 
 fore, be 0.075 watt, or about 30 percent of the power required to 
 operate the relay. This sholud not seriously interfere with the 
 operation of signals, as leakages up to 60 percent exist without 
 such serious interference. 
 
 It is to be regretted that determinations of resistance were not 
 made with wet ties or with ties and rails paitially immersed in 
 water, as is' sometimes the case in practice, for it is believed that 
 under such conditions the leakage current would probably be 
 su;fficiently large to interfere with the successful operation of 
 relays. 
 
 As a final conclusion, it should be noted that since the above 
 results show only a reduction in resistance of a tie of from 26 to 
 53 percent when treated with zinc chloride, depending upon the 
 percentage of moisture, while a change of resistance by the ratio 
 of 25 to 1 may be effected by varying the kind of wood, a change 
 of 33 to 1 by varying the pressure upon the tie sufiiciently, and of 
 3.7 to 1 by temperature changes, it follows that the treatment of 
 ties with preservatives should not interfere With the operation of 
 signal circuits, except possibly in exceptional cases in which the 
 resistance of the leakage paths is abnormally low from o'ther 
 ■causes." 
 
 From a number of inquiries, it is the experience of several 
 signal engineers that little or no difficulty will be experienced with 
 zinc treated ties if the distance between signal blocks is not too 
 great and if the ties are not laid green. Some of them have 
 shortened the distance between signals to about 1000 to 1200 feet 
 and report complete satisfaction. Against creosoted ties no com- 
 plaint on this account is made. 
 
 A number of traction companies state that the zinc-treated 
 ties corrode their spikes very rapidly and for this reason they are 
 opposed to using them. It is entirely possible that this will occur, 
 
 16 
 
242 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 especially if the ties are liable to hold much Inoisture and are 
 situated a long distance from the power house. Ties which can 
 be kept fairly dry, and can be laid close to the power house so that 
 the return current will be through them, rather than away from 
 them, should give little trouble. 
 
 The leakage in current in poles and cross arms treated with 
 soluble salts should be very slight and of little or no practical 
 consequence since they are not counted upon for insulation, 
 this being taken care of by the insulators themselves. However, 
 it seems entirely probable that creosoted poles and arms will tend 
 to resist leakage more than those which are salt treated because 
 they will, in general, contain less moisture. As already stated, 
 such a difference can at most have little practical significance and 
 for this reason treated poles can undoubtedly be used in the same 
 manner as untreated poles. 
 
CHAPTER XIX 
 THE USE OF SUBSTITUTES FOR TREATED TIMBER 
 
 By the term "substitute" is here meant a material which is 
 offered in place of wood, wood having been the standard. Thus, 
 although wood and asphalt are both used extensively for street 
 pavements, asphalt is not considered a substitue for wood but a 
 competitor of wood. On the other hand a concrete tie is a 
 "substitute" for the wood tie. With this distinction in mind, 
 a clearer conception of the inroads being made by other materials 
 can be had. It is not intended to discuss in this chapter the 
 general substitution of other materials for wood but only for 
 treated wood. This has taken place in a wide variety of products 
 and, in certain instances, is making rapid headway. It is caused 
 by the rise in the price of ti;nber, the demand for better con- 
 struction and an improvement in the manufacture of the sub- 
 stitutes. 
 
 Substitutes for Wood Ties. — This was one of the first fields 
 entered and thousands of dollars have been spent in attempting to 
 find a satisfactory substitute for wood ties. Ties made of steel, 
 concrete, leather, and combinations of these materials have all 
 been tested both in this country and abroad. Best success has 
 been had with the steel ties, but their introduction has been very 
 slow, and the results secured from them by no means all that is re- 
 quired. The American Railway Engineering Association has gone 
 rather extensively into this problem and has made a report con- 
 taining much valuable data. ^ It states that " an improved form of 
 steel tie, as shown in Plate XXII, Fig. C, of the type manufac- 
 tured by the Carnegie Steel Co. with metal plate over the insu- 
 lating fiber and with the wedge clip rail fastening, seems to be 
 very promising." A few railroads report satisfactory experience 
 with the steel tie, while other companies have discarded them. 
 The general consensus of opinion at present seems to be that 
 these ties are still in the experimental stage but worthy of trial. 
 
 As a result of its studies, the American Railway Engineering 
 
 ' Bulletin 108, American Railway Engineering Association, 1909. 
 
 243 
 
244 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 Association committee concludes "that no form of reinforced 
 concrete tie has been made which is suitable for heavy and high- 
 speed traffic, but believes a properly reinforced concrete tie, with 
 proper fastenings, may be foxind economical in places where speed 
 is slow and where conditions are especially adverse to the life of 
 wood or metal." The Lake Shore & Michigan Southern Railroad 
 placed some "Buhrer Concrete Ties" in its track at Sandusky, 
 Ohio, in 1904. There were no renewals up to 1908 and all the 
 ties appeared in good condition. The more common experience, 
 however, seems to be like that of the Pennsylvania Railroad, which 
 placed 500 of these ties in 1903. " The concrete broke and crum- 
 bled and by December, 1906, all had been removed on account 
 of breaking." Kimball, Tercival, Affleck, Chenoweth, Keefer, 
 Hickey and Alfred concrete ties tested by various railroads all 
 cracked or crumbled in 2 or 3 years although in a few cases longer 
 lives were secured. It appears, therefore, that a satisfactory 
 substitute for the treated wooden tie still remains to be found. 
 
 Substitutes for Wood Poles. — Iron, concrete and glass have 
 been tested for poles. In cities, the iron pole has given very good 
 use and has very largely replaced the wood poles. However, in 
 the larger cities, even the iron pole has been done away with, ex- 
 cept for street lighting, its place being taken by conduits. Wood 
 poles are still used in large quantities in towns and cities and in 
 the country for trolley, telephone, telegraph and high power trans- 
 mission lines, although with the latter, steel towers furnish the 
 best construction. Concrete poles are largely in the experimental 
 stage as yet. Poles 100 feet or more in length have, however, been 
 constructed of reinforced concrete. On account of their great 
 weight, high cost, and difficulty of handling, it is doubtful whether 
 concrete poles will make serious inroads on wood poles for years 
 to come, except perhaps in isolated cases. Concrete poles have 
 not been in service long enough to know their merits. 
 
 Glass poles are purely an experiment and, from the results 
 secured thus far, success seems doubtful. 
 
 A review of past experiences shows that only in large cities has 
 any material been successfully substituted for wood in the manu- 
 facture of poles, and that no substitute which gives promise of 
 extended usage is in demand. 
 
 Substitutes for Wood Piling. — Wrought iron, cast iron, steel 
 and reinforced concrete have all been used for piles. Iron in all 
 its forms is, of course, free from attack by the marine borers. 
 
USE OF SUBSTITUTES FOB TREATED TIMBER 245 
 
 It corrodes, however, when driven in sea water. Wrought iron 
 apparently corrodes more rapidly than steel which contains 
 about 0.1 percent of carbon. Cast iron becomes pitted, the iron 
 being gradually dissolved leaving the carbon. The hfe of iron 
 piles is not knowfi, but from tests made by various investigators, 
 it appears that wrought iron and steel will corrode at the rate of 
 about 0.40 inches per 100 years. The actual usefulness of the 
 pile will depend largely upon the extent to which it becomes pitted 
 and apparently this varies between very wide limits. 
 
 Reinforced concrete piles have been used since 1896 and large 
 numbers have been placed in various harbors of the world. 
 These piles, are attacked at times by the sea water, which 
 disintegrates them. Furthermore, alternate freezing and thaw- 
 ing have, in cases, cleaved off much of the concrete. Yet in 
 spite of these difficulties, concrete piles possess considerable merit 
 and give promise of being perfected to an extent where they will 
 prove free from these objections. Concrete piles have not been 
 used sufficiently long or driven in sufficient numbers and under 
 such conditions as to furnish reliable data on their probable life. 
 
 Substitutes for Wood Posts. — Considerable progress has been 
 made in manufacturing concrete posts, and several railroads in our 
 country are now using large quantities of them. The cost of 
 making the posts varies from about 16 to 25 cents each. Nothing 
 is known of their life, but this is estimated by several manufac- 
 tures to be at least 40 years. Concrete posts are heavy, trouble- 
 some to make, liable to be thrown by frost heave, require careful 
 handling and have other ills, but in spite of them all, they 
 possess much merit, particularly because of their durability and 
 appearance, and have unquestionably come to stay and their con- 
 sumption will increase. (See Plate XXII, Fig. D.) 
 
 Posts are also made of cast iron, iron pipe and galvanized sheet 
 iron, but the number is so small as to be insignificant and prob- 
 ably will always remain so, except for a comparatively few 
 special cases. 
 
 Substitutes for Wood Mine Timbers. — Concrete, masonry and 
 steel have all been substituted for wood mine timbers, but only 
 in isolated cases. Concrete mine timbers are very expensive, 
 their installation interferes with the working of the mine and in 
 some cases they are crushed before they become "set." It is 
 doubtful if they will come into general use. (See Plate XXII, 
 Fig. A.) Iron mine " timbers " have been tested both here and in 
 
246 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 Europe. They are expensive, difl&cult to install, and are corroded 
 by the mine gases and water. Furthermore, if the mine once 
 starts to "cave," the iron "timbers" will fail although they will, 
 of course, hold a greater load than wood. In Europe a unique 
 method in the design of iron props has been tested. It consists 
 of two hollow pipes, one of which fits snugly inside the other. 
 Round iron balls are then placed in the lower pipe. In this man- 
 ner the upper pipe can be extended and held by the balls, pre- 
 venting further telescoping. When it is desired to remove the 
 prop, a plug in the lower pipe is opened and the balls allowed to 
 roll out. This makes a prop which can be fitted into place. Its 
 cost, of course, is high and in addition it is subject to most of 
 the objections raised against iron mine "timbers." Our largest 
 iron and steel company is using enormous quantities of wood in 
 its own mines, some of which is treated with preservatives. 
 Masonry, is, of course, out of the question because of its high 
 cost, trouble in laying, etc., except for very unusual situations, 
 so it doubtless will never become a serious rival to other forms 
 of "timbering." 
 
 Substitutes for Wood Bridge Timbers. — Steel, masoruy and re- 
 inforced concrete have almost entirely replaced wood in the 
 construction of permanent bridges. In addition to possessing 
 greater strength, such bridges are less subject to destruction by 
 fire. In so far as durability between steel and wood bridges is 
 concerned, doubt still exists in the niinds of some engineers and 
 conflicting data have been submitted. Creosoted wood bridge 
 timbers are known to have existed in perfect condition for over 
 30 years in the South where decay is generally rapid. Appre- 
 hension of the gradual deterioration ("fatigue") of such timber 
 due to repeated impacts, does not appear well founded. Some 
 railroads in our country are laying creosoted bridge timbers on top 
 of steel members, thus adding to the elasticity of the bridge and 
 deadening of sound. Considerable quantities of wood are still 
 used on steel bridges in the form of ties, guard rails, wall plates, 
 etc., and in wooden bridges and trestles, but as the demand for 
 high grade permanent structures increases, the use of wood will 
 unquestionably decrease. It is likely, however, that a demand 
 for wood shields under steel bridges which are subject to corro- 
 sion from the locomotive stacks will increase, especially when the 
 wood is rendered noninflammable. 
 
Plate XXIII 
 
 Fig. a. — Concrete mine props, Pennsylvania. (Forest Service photo.) 
 
 
 
 "1-S^M> 
 
 ^im\m.: 
 
 ^^^ ' ™^ 
 
 ^^M 
 
 Fig. B. — Indiana Tie Company's wood preserving plant, Joppa, 111. 
 Note depressed tracks and manner of running cylinder cars on flat cars for 
 loading ties into box cars for shipment. 
 
 (Focins page 246.) 
 
Plate XXIII 
 
 Fig. C. — Nest box used to protect poles and buildings from attack by 
 woodpeckers. (Photo courtesy Ernest Baynes.) 
 
 Fig. D. — Wood dowels screwed into softwood ties as a protection against 
 
 spike cutting. 
 
USE OF SUBSTITUTES FOR TREATED TIMBER 247 
 
 Substitutes for Wood in Buildings and Cars. — As only small 
 quantities of treated wood are used in the construction of 
 buildings and cars, the substitution of other materials affects but 
 little the wood preserving industry. 
 
 A special committee of the American Railway Association ap- 
 pointed in 1912 circularized the railroads of the United States 
 and received reports from 247 railroad companies operating 
 227,754 miles of track. The object of the circular was to ascer- 
 tain the progress being made in introducing steel passenger cars 
 in place of wooden cars. The following table summarizes the 
 findings of this committee : 
 
 
 Total 
 number 
 
 Steel, 
 percent 
 
 Percentages 
 
 steel Uner 
 
 frame 
 
 Wood, 
 percent 
 
 1909. 
 
 1880 
 3638 
 3756 
 2660 
 1649 
 
 26.0 
 55.4 
 59.0 
 
 68.7 
 85.2 
 
 22.6 
 14.8 
 20.3 
 20.9 
 11.5 
 
 "51.4 
 29.8 
 20,7 
 10.4 
 3.3 
 
 1910. 
 
 1911. . 
 
 1912 
 
 January, 1912 
 
 (Under construction) 
 
 The substitution of steel for wood in freight cars is also taking 
 place at a rapid rate. While opinions vary widely at present, it 
 appears that a combination of steel and wood will be the ultimate 
 solution of many of the freight car problems. Similar changes 
 are taking place in the construction of buildings in cities where 
 the tendency is to reduce the fire hazard to a minimum. Steel, 
 concrete, and clay products have replaced wood to a very 
 large extent and there is little doubt but what such replace- 
 ment is permanent. In certain cases, however, a reaction has 
 set in, as it was found that many buildings supposedly "fire- 
 proof" were really not so when put to the test. Thus wood 
 floors and trim will probably remain for years to come. "Slow 
 burning" factory construction has also been in demand. It is 
 believed that "fireproofing" wood used in such buildings will do 
 much to remove some of the serious objections raised against 
 wood and that this phase of the wood-preserving industry will 
 grow to much larger proportions than at present. 
 
 Substitutes for Wood Shingles. — There is a great variety of 
 roofing materials such as metal, slate, tile, asbestos, etc., now on 
 the market which are replacing shingles. This has been brought 
 about largely through the demand for fireproof construction — 
 
248 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 certain cities having passed ordinances prohibiting the use of 
 wood shingles within their congested hmits. As buildings be- 
 come more crowded and permanent, wood is invariably replaced. 
 In general, roofs built of these "substitute" .materials cost more 
 than shingle roofs, not only for the covering itself, but for the con- 
 struction necessary to hold up the greater weight. It is possible 
 that the progress being made in "fireproofing" shingles, will do 
 much to retain their existence. If this one very serious objection 
 could be removed, wood shingles would remain in favor. They 
 possess certain characteristics such as cheapness, ease of repair, 
 light weight, adaptability to artistic design, durability, resistance 
 to heat transmission, etc., which are in strong demand. 
 
 Substitutes for Wood Conduits and Pipes. — The use of treated 
 wood for these purposes is quite small, and forms but a small 
 percentage of the total amount. Fiber conduit, tile, brick, and 
 steel are all used in large quantities. Creosoted wood conduit is 
 very durable and has given excellent service. It is comparatively 
 inexpensive, easily laid and resistant to injury from settlement 
 of the surrounding earth. The oil will, of course, attack rubber 
 and under certain conditions cannot be used. Large quantities 
 of wood have been used in building pipes, particularly for irrigat- 
 ing purposes. One decided advantage seems to be a lowering in 
 the coefficient of friction through use — a result quite the opposite 
 of metal, which tends to become rough and hence decrease the 
 quantity of water which flows through it. 
 
CHAPTER XX 
 APPENDICES 
 
 Minor Wood-preserving Processes. — No attempt is made to 
 list and describe all of the various processes which have been 
 advanced in this country to preserve wood from decay. To do so 
 would prolong this book to several volumes. Some idea of the 
 number of wood-preserving processes suggested can be gained 
 by examining the list of patents given below. But to inform those 
 who might wish information on this phase of wood preservation, 
 a number of the better-known and more interesting methods 
 will be briefly discussed. Some of them may eventually be 
 extensively practised in our country. 
 
 Thilmany Process. — Patented by Thilmany in 1876, the proc- 
 ess consists in impregnating wood with copper sulphate (later 
 zinc sulphate was substituted) followed by a second injection of 
 barium chloride. The object was to produce a chemical reaction 
 giving copper chloride and barium sulphate; the latter being 
 insoluble in water was intended to plug the wood and prevent the 
 copper chloride from leaching out. The process was tested by 
 several railroads in this country without apparent success. 
 
 The B-M Timber-preserving Process. — This process uses 
 a combination of zinc chloride and aluminum sulphate as 
 covered by patents held by Hubertumtihle of Schopfurth, 
 Mark, Germany. It is claimed that the aluminum sulphate is 
 not only an antiseptic salt, but gives a better solution to the zinc 
 chloride and carries this salt deeper into the wood. It is also 
 claimed to combine in part with the wood structure. The 
 solution is injected into timber much in the same manner as zinc 
 chloride in the Burnett process except that the temperatures are 
 kept somewhat lower. From analyses of treated wood made by 
 certain reputable chemists, it appears that better penetrations are 
 secured in the B-M process than in the straight Burnett process. 
 Some treating companies in the United States are now ready to 
 treat timber by this process. 
 
 249 
 
250 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 The Goltra Process. — Named after W. F. Goltra of Cleveland, 
 Ohio. For handling ties the distinct steps in the process are: 
 (a) Steaming ties upon delivery at plant. 
 (6) Stacking ties for open-air seasoning. 
 
 (c) Machining ties. 
 
 (d) Drying and warming ties in ovens. 
 
 (e) Impregnation with antiseptic liquid. 
 
 The novel features in the process are the steaming of the ties 
 on delivery at the plant and then air -seasoning them; also 
 warming the ties in ovens before injecting the preservative. So 
 far as the author knows, this process is not in commercial use, 
 although it has been considerably agitated in the past few years. 
 
 The Hasselman Process. — Patented in the United States in 
 1897. This process consists essentially in injecting into wood 
 a solution containing sulphates of iron and aluminum to which 
 "Kainit" is added to neutralize the free acids which may be 
 formed. The process was tested experimentally in Texas with 
 poor results. Since then certain modifications of the process 
 have been proposed by Barschall and some timber treated in this 
 manner is now under test by the United States Forest Service 
 with no conclusive results to date. 
 
 The Creo-Resinate Process. — First practised by the United 
 States Wood Preserving Company, particularly for the treatment 
 of paving blocks. The wood is subjected to a dry heat, after 
 which a vacuum is drawn and the creo-resinate mixture forced 
 into the wood. This mixture consists of creosote (about 50 
 percent), 48 percent rosin, and 2 percent formaldehyde. A 
 subsequent treatment with a solution of lime is then given. It is 
 understood that the original treatment has undergone considerable 
 change since it was first advocated. 
 
 Robbins' Process. — Practised by the Suffold Wood Pre- 
 serving Company of Boston about 1869. It consisted in passing 
 vapor of naphtha into the retort after the wood had been run into 
 it, the vapor being heated to about 250-300° F. This vapor 
 was to expel the water from the wood, coagulate the albumen, 
 and expand the wood pores. The temperature in the retort 
 was then raised to 400° F. and vapor of creosote passed into the 
 wood. The process was tested extensively, but failed. 
 
 Powell Process. — This is an English process which has been 
 tested extensively abroad but is little known in our country. 
 It consists in boiling wood in a solution of sugar for a few hours 
 
APPENDICES 251 
 
 and then drying it in an oven at high temperatures. It is said 
 to render wood resistant to ants and decay and nonabsorptive 
 to water. Tests known to the author indicate the process has 
 decided merit in overcoming the hygroscopicity of wood. 
 
 Creoaire Process. — Advertised by the International Creosot- 
 ing & Construction Co. It consists in treating wood similar 
 to that employed in the full-cell creosote process, but after the 
 desired amount of oil is forced into the timber the cylinder is 
 drained of excess oil and an air pressure applied to drive the oil 
 further into the wood, thus producing an "empty-cell" effect. 
 Tests made by the author show that this method drives con- 
 siderable oil out of the wood and may cause "bleeding." 
 
 Vulcanizing Process. — Practised by the New York Vulcaniz- 
 ing Company of New York City. Sometimes called "Haskins' 
 process." The timber is placed in the treating cylinder. Air 
 compressed to 150 to 200 pounds per square inch is then forced 
 into the wood through a water separator to remove moisture, 
 and heated to about 400 to 500° F. for about 8 hours. The 
 process rapidly removes the water from the wood, and producing 
 a partial distillation, is claimed to render it antiseptic. A large 
 number of ties have been treated by this process, some of which 
 gave long service. 
 
 Cresol-calcium Process. — This is a Swedish process not 
 practised in this country except experimentally. Agents are 
 Blagden-Waugh Company of London. The timber is handled 
 much as in Burnettizing except that the solution consists of a 
 mixture of milk of lime and crysilic acid resulting in calcium 
 crysilate. It is under test in several places in the United States 
 but apparently with little success. 
 
 PATENTED, PROPRIETARY, AND MINOR WOOD PRESERVA- 
 TIVES USED IN THE UNITED STATES 
 
 A number of wood preservatives which fall under this heading 
 are used in the United States, few of them in any appreciable 
 amount. Perhaps the best known are the "carbolineums," 
 which are used quite extensively, especially for brush-treating 
 timber. 
 
 Cresol-calcium. — This is handled by Bladgen-Waugh & 
 Company, London, England, Messrs. Heidenstam and Freid- 
 mann being the inventors. It has been tested experimentally 
 
252 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 in the United States but is not used commercially here. The 
 results secured thus far have not been very s,atisfactory. The 
 preservative consists essentially of cresol ("tar acids") and 
 milk of lime mixed in varying concentration up to 15 percent in 
 strength and impregnated in a manner similar to Burnettizing. 
 
 S. P. F. Carbolineum. — Handled by Bruno-Grosche & Co. 
 of New York City. It is a preservative distilled from tar, which, 
 according to the engineering department of the American Tele- 
 phone and Telegr'aph Company, is somewhat similar on distil- 
 lation to Avenarius Carbolineum. It has been used in this 
 country for many years and has given good results. 
 
 Avenarius Carbolineum. — Made in Germany, but handled by 
 the Carbolineum Wood Preserving Company of Milwaukee, 
 Wis., and other cities. It is essentially a high-grade distillate 
 of coal-tar specially manufactured and has been used in this 
 country for many years with good results. 
 
 C-A-wood Preserver. — A foreign-made product handled in 
 this country by the C-A-Wood Preserver Company of St. Louis, 
 Mo., with agencies in other cities. Essentially a high-grade 
 distillate of coal-tar, which has been used in this country for many 
 years with good results. 
 
 Timberasphalt. — Sold by the Indian Refining Company of 
 New York City. It is an "asphaltic flux" resulting from the 
 refining of crude oil, and has no marked antiseptic properties, 
 relying more on its waterproofing and "plugging" action to 
 preserve wood. It is one of the more recent preservatives 
 placed on the market. 
 
 Preservol. — Sold by the Newbold Manufacturing Company, 
 135 Greenwich Street, New York City. Said to be a "creosote" 
 made from beech. It has not been very extensively tested in this 
 country. 
 
 Copperized Oil. — Handled by the Copper Oil Products Com- 
 pany of New York City. It is an oil containing copper. The 
 kind of oil used and amount of copper it contains apparently can 
 be varied for specific requirements. It is one of the new preser- 
 vatives placed on the market. 
 
 Sodium Silicate. — Made by several companies in the United 
 States. It does not readily penetrate wood, but has a marked ten- 
 dency to decrease the inflammability of wood. 
 
 Spirittine. — Manufactured by the Spirittine Chemical Com- 
 
APPENDICES 253 
 
 pany of Wilmington, N. C. This is a special "creosote" made 
 from coniferous wood, and has been used quite extensively in the 
 United States with good results. 
 
 B. M. Preservative.— The agent in this country is Franz 
 Workman, 31 Liberty Street, New York City. It is a mixture of 
 zinc chloride and normal aluminum sulphate, and has been tested 
 experimentally on a large scale in this country but has not been 
 commercially practised to any appreciable extent. It is forced 
 into wood in much the same manner as in Burnettizing. 
 
 Water-Gas Tar Creosote. — Made by a number of companies 
 in the United States but seldom sold under its own name. Often 
 mixed with coal-tar creosote. Tests by the U. S. Forest Service 
 show it to have considerable merit as a wood preservative, but not 
 as efficient for general purposes as coal-tar creosote. 
 
 Holz-Helfer. — Handled by the Vaughn Paint Co. of Cleveland, 
 Ohio, and made in Germany. The wood is either painted with or 
 dipped in the solution. It is a greenish-brown liquid containing 
 zinc chloride, copper, and creosote with a specific gravity at 60° C. 
 of 1.113. From tests made at the U. S. Forest Products Lab- 
 oratory it appears to be much less toxic than creosote. 
 
 Wood Creosote. — Made by several companies in the United 
 States but not used extensively. Tests by U. S. Forest Service 
 show it to have considerable merit as a wood preservative and its 
 use for this purpose will quite Hkely grow, especially for super- 
 ficial treatments. At present it varies greatly in composition and 
 toxic properties and costs more than coal-tar creosote. 
 
 Sodium Fluoride. — Made by large manufacturing chemists 
 in the United States. Little known in this country but exten- 
 sively tested abroad. Experiments by the U. S. Forest Products 
 Laboratory indicate the possibility of using this salt to decided 
 advantage. Further tests are necessary before is full value is 
 known. It is impregnated into wood as in the Burnettizing 
 process. 
 
 Aczol. — Manufactured by J. Gerlache, Boulevard du Nord, 
 68 Brussels, Belgium. This is a cuprous-ammonium salt, which 
 is not used to any extent as yet in the United States but is under- 
 going experiments with the U. S. Forest Service. 
 
 Sapwood Antiseptic. — Made and patented by J. W. Long, 
 Chicago, 111. It is a mixture of copper sulphate, sodium chloride, 
 calcium sulphate, zinc sulphate, and iron sulphate with water. Is 
 now undergoing test by the U. S. Forest Products Laboratory and 
 
254 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 elsewhere. Is claimed to prevent sap stain as well as decay. 
 Toxic tests show it to possess a very low resistance to fungi. 
 
 N. S. Special. — Manufactured by the Geo. W. Saums Co, 
 Trenton, N. J. It is a yellowish, oily liqiud with a strong varnish 
 or paint odor. Tests made at the U. S. Forest Products 
 Laboratory show it to have a low resistance to fungi. 
 
 Imperial Wood Preservative. — This is a comparatively light 
 gravity, greenish-black oil, handled in St. Louis, Mo., containing 
 a high percentage of jesidue at 315° C. It is under test by the 
 U. S. Forest Service and elsewhere, and is giving results not very 
 unlike those obtained from coal-tar creosote. 
 
 Kreodone. — This is a special wood-preserving oil made by 
 the Republic Creosoting Company of Indianapolis, Ind., and else- 
 where and used largely for preserving wood blocks. It is reported 
 as giving good service. 
 
 Locustine. — Manufactured by W. H. Huff, Beverly, N. J. 
 It is reported as being a patented compound of nonvolatile pe- 
 troleum products and certain animal and marine oils and anti- 
 septics, which can be applied to wood either by the brush, dipping, 
 or impregnation processes. 
 
 Creoline. — This is a very light gravity, brown oil containing 
 much tar acids and water. In spite of this it is giving good results 
 in some test pole lines set under the supervision of the U. S. 
 Forest Service and the Bell Telephone Company. 
 
 LIST OF MANUFACTURERS OF ZINC CHLORIDE IN THE 
 UNITED STATES 
 
 General Chemical Co. 112 W. Adams St., Chicago, lU. 
 Graselli Chemical Co. Cleveland, Ohio. 
 Sandoval Zinc Company. East St. Louis, HI. 
 
 LIST OF MANUFACTURERS OR DEALERS OF CREOSOTE IN 
 THE UNITED STATES 
 
 American Conduit Company, East Chicago, Ind. 
 Armitage Manufacturing Company, Richmond, Va. 
 American Wood Preserving Company, Chicago, 111. 
 
 Barrett Manufacturing Company, New York, Chicago, and various 
 ofi&ces. 
 Barnay, J. R., Seattle, Wash. 
 Betts, C. G., Spokane, Wash. 
 
 Burton Coal and Lumber Company, Salt Lake City, Utah. 
 Carolina Portland Cement Co., Atlanta, Ga. 
 
APPENDICES 
 
 255 
 
 Creosote Supply Co., Chalmette, La. 
 
 Chatfield Manufacturing Co., Carthage, Ohio. 
 
 Coal-tar Products Company of New York. 
 
 Clintock & Irvine Co., Pittsburgh, P'a. 
 
 Dominion Tar and Chemical Company, Sidney, Nova Scotia. 
 
 Diem & Wing Paper Co., Cincinnati, Ohio.' 
 
 Denver Gas & Electric Co., Denver, Colo. 
 
 International Creosoting Construction Co., Galveston, Texas. 
 
 C. Lembcke & Company, New York City. 
 
 J. F. Lewis Manufacturing Co., Chicago, 111. 
 
 National Analine & Chemical Co., New York City. 
 
 Nashville Chemical Co., Nashville, Tenn. 
 
 Pehlam Bay Chemical Co., Mount Vernon, N. Y. 
 
 Pacific Cresoting Co., Seattle, Wash. 
 
 Republic Creosoting Co., Minneapolis, Minn. 
 
 Semet-Solvay Company, Kingsley, Ala. 
 
 Southern Roofing Company, Atlanta. 
 
 United Gas Improving Co., Philadelphia, Pa. 
 
 Utah Light & Railway Co., Ogden, Utah. 
 
 Warren Brothers, Cambridge, Mass. 
 
 Western Electric Company, Salt Lake City, Utah. 
 
 Zopher Mills, 91 WUliams St., Brooklyn, N. Y. 
 
 LIST OF WOOD-PRESERVING PLANTS IN THE UNITED STATES 
 EASTERN STATES 
 
 
 
 Year 
 
 built 
 
 No. 
 
 Diam. 
 
 Length 
 
 Location of plant 
 
 Managing company 
 
 of re- 
 
 retorts 
 
 retorts 
 
 
 
 torts 
 
 (in.) 
 
 (feet) 
 
 Long Island City, N. Y. 
 Rome, N. Y 
 
 
 1878 
 
 4 
 
 72 
 
 100 
 
 Federal Oreo. Co 
 
 1910 
 1909 
 
 2 
 1 
 
 84 
 84 
 
 150 
 150 
 
 Bound Broolc, N.J 
 
 Federal Oreo. Co 
 
 Newarlc, N. J 
 
 American Creosoting Co 
 
 Federal Creo. Co 
 
 1906 
 
 2 
 
 78 
 
 105 
 
 
 1909 
 
 1 
 
 84 
 
 150 
 
 Maurer. N Y. 
 
 Barber Asphalt Pav. Co 
 
 1905 
 
 i 
 
 72 
 
 115 
 
 Port Reading, N. J.... 
 
 P. &R. R. R., C. R. R. of N. J... 
 
 1912 
 
 2 
 
 88 
 
 140 
 
 Greenwich, Pa 
 
 Penna. R. R 
 
 1910 
 
 2 
 
 72 
 
 132 
 
 Mt. Union, Pa 
 
 Penna. R. R 
 
 1909 
 
 1 
 
 72 
 
 132 
 
 Broadford Jo., Pa 
 
 Pittsburgh Wd. Pres. Co 
 
 1911 
 
 1 
 
 84 
 
 132 
 
 Bradford, Pa 
 
 Buff., Rooh. & Pgh. R. R 
 
 1910 
 
 1 
 
 75 
 
 95 
 
 Buell, near Norfolk, Va 
 
 U. S. Wood Prea. Co 
 
 1907 
 
 2 
 
 78 
 
 150 
 
 Buell near Norfolk. Va 
 
 Norfolk Creosoting Co 
 
 1896 
 
 i 
 
 78 
 
 100 
 
 
 
 
 1 
 
 78 
 
 105 
 
 
 
 1905 
 
 1 
 
 84 
 
 125 
 
 Norfolk, Va 
 
 Atlantic Creo. & Wood Preserving 
 
 
 1 
 
 78 
 
 62 
 
 
 Co. 
 
 
 1 
 
 78 
 
 82 
 
 
 
 1901 
 
 1 
 
 78 
 
 126 
 
 Portamouth, Va 
 
 Wyokoff Pipe & Creo. Co 
 
 1881 
 
 4 
 
 74 
 
 102 
 
 Green Spring, W. Va... 
 
 Balto. & Ohio R. R 
 
 1912 
 
 2 
 
 84 
 
 132 
 
256 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 Southern States 
 
 Location of plant 
 
 Managing company- 
 
 Year 
 built 
 
 No. 
 of re- 
 torts 
 
 Diam. 
 
 retorts 
 (in.) 
 
 Length 
 retorts 
 (feet) 
 
 Gainesville, Fla 
 
 Fensacola, Fla 
 
 Jacksonville, Fla 
 
 Hull, Fla 
 
 Macon, Ga 
 
 Atlanta, Ga 
 
 Ensley, Ala 
 
 Mobile, Ala 
 
 McAdory, Ala 
 
 Southport, near New 
 Orleans, La. 
 
 New Orleans, La 
 
 Slidell, La 
 
 Shreveport, La 
 
 Winnfield, La 
 
 Bogalusa, La 
 
 Grenada, Miss 
 
 Gulfport, Miss 
 
 Gautier, Miss 
 
 Louisville, Miss 
 
 Argenta, Ark 
 
 Texarkana, Ark 
 
 Beaumont, Tex 
 
 Denison, Tex 
 
 Texarkana, Tex 
 
 Houston, Tex 
 
 Houston, Tex 
 
 Somerville, Tex 
 
 Hugo, Okla 
 
 Atlantic Coast Line R. R 
 
 Southern Pav. Con. Co 
 
 Eppinger & Russell Co 
 
 Charlotte Harbor and Nor. Ry. 
 Co. 
 
 Central of Ga. R. R. Co 
 
 Southern Wd'. Pres. Co 
 
 Pioneer Lum. & Creo. Co 
 
 Republic Creoaoting Co 
 
 Tennessee Coal, Iron and Rail- 
 road Co. 
 
 American Creosote Wks 
 
 1912 
 1912 
 1909 
 1912 
 
 1912 
 1908 
 1911 
 1906 
 1909 
 
 New Orleans Wd. Pr. Co. . 
 Southern Creosoting Co. . . 
 
 Shreveport Creo. Co.. 
 Louisiana Creo. Co. . . 
 Colonial Creo. Co 
 
 1901 
 1888 
 1879 
 1902 
 1910 
 1906 
 
 Ayer & Lord Tie Co 
 
 Gulfport Creo. Co 
 
 W. Pascagoula Creo. Wks. 
 
 American Creo. Wks. . 
 Ayer & Lord Tie Co. . , 
 Int. Creo. & Con. Co. . 
 
 Int. Creo. & Con. Co. . 
 
 1912 
 1904 
 1906 
 1876 
 1903 
 1912 
 1907 
 
 Mo. Kan. & Tex. Ry. Co. of Texas 
 
 Nat. Lum. & Creo. Co 
 
 Nat. Lum. & Creo. Co 
 
 Tex. & N. O. R. R. Co 
 
 A., T. & S. F. R. R 
 
 American Creo. Co 
 
 1902 
 1892 
 1897 
 1909 
 1910 
 1912 
 1890 
 1906 
 1907 
 
 74 
 72 
 84 
 74 
 
 84 
 72 
 74 
 74 
 72 
 
 84 
 108 
 72 
 84 
 72 
 84 
 72 
 72 
 72 
 74 
 84 
 72 
 72 
 108 
 74 
 114 
 72 
 
 108 
 72 
 84 
 72 
 72 
 74 
 84 
 
 138 
 90 
 
 130 
 73 
 
 116 
 70 
 76 
 
 130 
 65 
 
 172 
 172 
 125 
 150 
 100 
 134 
 126 
 80 
 134 
 128 
 120 
 119 
 115 
 172 
 132 
 165 
 125 
 
 140 
 108 
 132 
 120 
 112 
 132 
 134 
 
APPENDICES 
 
 257 
 
 Central States 
 
 Location of plant 
 
 Managing company 
 
 Year 
 built 
 
 No. 
 of re- 
 torts 
 
 Diam. 
 
 retorts 
 
 (in.) 
 
 Length 
 retorts 
 (feet) 
 
 Toledo, Ohio 
 
 Federal Creo. Co. 
 
 1909 
 1910 
 1912 
 1909 
 1903 
 1905 
 1904 
 1912 
 1907 
 1909 
 
 1907 
 1907 
 
 3 
 2 
 
 1 
 1 
 1 
 2 
 2 
 2 
 1 
 1 
 
 2 
 2 
 4 
 4 
 2 
 
 84 
 72 
 84 
 72 
 74 
 84 
 72 
 132 
 84 
 72 
 
 72 
 72 
 72 
 74 
 84 
 
 134 
 130 
 132 
 
 76 
 130 
 134 
 120 
 
 20 
 134 
 
 45 
 
 110 
 134 
 122 
 132 
 134 
 
 Toledo, Ohio 
 
 
 Orrville, Ohio 
 
 
 Cincinnati, Ohio 
 
 Indianapolis, Ind 
 
 Comp. Wd. Pres. Co 
 
 
 
 Terre Haute, Ind 
 
 Terre Haute, Ind 
 
 Bloomington, Ind 
 
 Columbus, Ind 
 
 Evansville. Ind 
 
 Waukegan, 111 
 
 Carbondale, 111 
 
 Marion, 111 
 
 Indiana Zinc-Creo. Co 
 
 Chicago Creosoting Co 
 
 
 IndianapoUs, Columbia & South- 
 ern Trac. Co. 
 
 
 Aver & Lord Tie Co 
 
 
 1902 
 1907 
 
 Springfield, 111 
 
 Madison, III 
 
 American Creo. Co 
 
 Kettle River Co 
 
 1909 
 1907 
 
 i 
 5 
 1 
 1 
 1 
 2 
 1 
 3 
 2 
 2 
 2 
 2 
 2 
 2 
 
 84 
 
 74 
 74 
 72 
 72 
 72 
 72 
 72 
 74 
 72 
 84 
 84 
 84 
 73 
 
 135 
 132 
 132 
 117 
 132 
 110 
 42 
 112 
 130 
 120 
 134 
 134 
 134 
 117 
 
 Galesburg, 111 
 
 Mt. Vernon, 111 
 
 Metropolis, 111. . . 
 
 C, B. &Q. R. R 
 
 T.J. Moss Tie Co 
 
 Joyce-Watkins Co 
 
 1899 
 1914 
 1909 
 1893 
 1903 
 1905 
 1904 
 1907 
 1907 
 1907 
 1909 
 
 
 Bay City, Mich 
 
 Escanaba, Mich 
 
 Minneapolis, Minn 
 
 Sandstone, Minn 
 
 Brainerd, Minn 
 
 Springfield, Mo 
 
 Kansas City, Mo 
 
 Topeka, Kansas 
 
 
 Chi. & N. W. Ry. Co 
 
 
 Kettle River Co 
 
 Nor. Pac. Ry 
 
 American Creo. Co 
 
 American Creo. Co 
 
 Union Pacific R. R 
 
 17 
 
258 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 Rocky Mountain and Pacific States 
 
 Location of plant 
 
 Managing company 
 
 
 No. 
 
 Diam. 
 
 Length 
 
 built 
 
 of re- 
 torts 
 
 retorts 
 (in.) 
 
 retorts 
 (feet) 
 
 1901 
 
 4 
 
 72 
 
 110 
 
 1907 
 
 2 
 
 84 
 
 134 
 
 1910 
 
 1 
 
 72 
 
 43 
 
 1899 
 
 2 
 
 74 
 
 132 
 
 1903 
 
 2 
 
 73 
 
 117 
 
 1908 
 
 1 
 
 84 
 
 10 
 
 1912 
 
 1 
 
 84 
 
 130 
 
 1912 
 
 1 
 
 84 
 
 65 
 
 
 1 
 
 84 
 
 117 
 
 
 1 
 
 72 
 
 83 
 
 1895 
 
 1 
 
 72 
 
 62 
 
 1912 
 
 
 
 
 1884 
 
 3 
 
 75 
 
 120 
 
 1906 
 
 8 
 
 73 
 
 125 
 
 1904 
 
 4 
 
 72 
 
 114 
 
 1912 
 
 2 
 
 84 
 
 136 
 
 1893 
 
 2 
 
 72 
 
 112 
 
 1912 
 
 1 
 
 72 
 
 65 
 
 19C2 
 
 2 
 
 72 
 
 106 
 
 1908 
 
 2 
 
 74 
 
 132 
 
 
 1 
 
 72 
 
 108 
 
 1889 
 
 1 
 
 72 
 
 138 
 
 1907 
 
 2 
 
 72 
 
 112 
 
 1908 
 
 2 
 
 72 
 
 117 
 
 Somers, Mont 
 
 Paradise, Mont 
 
 Butte, Mont 
 
 Sheridan, Wyo 
 
 Laramie, Wyo 
 
 Kellogg, Idaho 
 
 Tacoma, Wash 
 
 Yardley, Wash 
 
 Lowell, Wash 
 
 Seattle, Wash 
 
 Eagle Harbor, Wash. 
 Wyeth, Ore 
 
 St. Helens, Ore 
 
 Latham, Ore 
 
 Bulrington (near Port- 
 land) Ore 
 
 Alamogordo, N. Mex. 
 Albutjuerque, N. Mex. 
 Oakland, Cal 
 
 Los Angeles, Cal 
 
 San Pedro, Cal 
 
 Great Northern Ry. Co 
 
 Nor. Pac. Ry. Co 
 
 Anaconda Cop. Min. Co 
 
 C, B. & Q. R. R. Co 
 
 Union Pacific R. R. Co 
 
 Bunker Hill and Sullivan Mining 
 
 Co... 
 
 St. P. & Tacoma Lum, Co 
 
 Western Wd. Pres. Co 
 
 Puget Sd. Wd. Pres. Co 
 
 J. M. Colm9,n Co 
 
 Pacific Creosoting Co 
 
 Oregon- Washington R, R. and 
 Nav. Co. 
 
 St. Helens Creo. Co 
 
 Southern Pac. R. R 
 
 Columbia Creo. Co 
 
 El. Paso & S.W.R.R. Co 
 
 A. T. &S. F. Ry. Co 
 
 So. Pacific Ry 
 
 So. Pacific Ry 
 
 S. P. L. A. &S. L. R. R 
 
 Open-tank Plants 
 
 Location of plant 
 
 Managing company 
 
 Year 
 built 
 
 Lowell, Mass 
 
 Otis Allen & Son. . ; ... 
 
 1848 
 1875 
 1907 
 
 1908 
 1910 
 1908 
 1908 
 1908 
 1908 
 1909 
 1908 
 1910 
 1895 
 1909 
 1910 
 1910 
 1899 
 1906 
 
 Portsmouth, N. H 
 
 Otis Allen & Son 
 
 Ninticoke, Pa 
 
 Del. Lack. & West. R.R. Coal Mining 
 
 Dept. 
 
 Phila. and Reading Coal and Iron Co. . . 
 
 New Philadelphia, Pa 
 
 
 
 U. S. Wood Pres. Plant 
 
 Milan, 111 
 
 U. S. Wood Pres Plant 
 
 Stillwater, Minn 
 
 U. S. Wood Pres. Plant 
 
 Fountain City, Wis 
 
 U. S. Wood Pres. Plant. 
 
 Cleveland, Ohio 
 
 
 Lead, S. Dak 
 
 Homestake Mining Co 
 
 Portland, Ore 
 
 Carbolineum W. P Co 
 
 Lowell, Wash 
 
 Puget Sound W. P. Co 
 
 Butte, Mont 
 
 
 San Joaquin Light and Power Co 
 
 San Joaquin Light and Power Co 
 
 So. Pac. Ry. Co 
 
 San Miguel, Cal 
 
 Oakland, Cal 
 
 Newark, N.J 
 
 Public Service Corporation 
 
APPENDICES 
 
 259 
 
 LIST OF "FIREPROOFING" PLANTS IN THE UNITED STATES 
 
 New York, N. Y Standard Wood Treating Company. 
 
 New York, N. Y Electric Fireproofing Company. 
 
 THE AMOUNT OF WOOD PRESERVATIVES USED IN THE 
 UNITED STATES 
 
 Creosote and zinc chloride are by far the preservatives con- 
 sumed in largest quantities in the United States for preserving 
 timber. About 3,000,000 gallons of other preservatives such as 
 crude oil, carbolineum, and other varieties of preservatives de- 
 rived from coal-tar were used in 1912. In addition, copper sul- 
 phate, mercuric chloride, and aluminum sulphate were also used, 
 the exact amounts being unknown. The consumption of creo- 
 sote and zinc chloride for preserving wood is shown in Table 38. 
 
 Table 38. — She Approximate Amount op Ckeosote and zinc Chloride 
 Consumed in the United States' 
 
 Years 
 
 ' Creosote (gallons) 
 
 Zino chloride 
 
 (pounds) ; 
 
 all domestic 
 
 Domestic 
 
 Foreign 
 
 Total 
 
 1908 
 
 17,360,000 
 
 38,640,000 
 
 56,000,000 
 
 19,000,000 
 
 1909 
 
 13,862,000 
 
 37,569,000 
 
 51,481,000 
 
 16,215,000 
 
 1910 
 
 18,184,000 
 
 45,082,000 
 
 63,266,000 
 
 • 16,803,000 
 
 1911 
 
 21,511,000 
 
 51,517,000 
 
 73,027,000 
 
 16,360,000 
 
 1912, 
 
 31,136,000 
 
 52,531,000 
 
 83,666,000 
 
 20,762,000 
 
 (Over 100,000,000 gallons of cresote reported used in 1913) 
 
 AMOUNT OF TIMBER TREATED IN THE UNITED STATES 
 
 The amount of timber treated annually in the United States is 
 shown in Table 39. 
 
 In addition to the amount shown in Table 39, a considerable 
 amount of wood was treated with other preservatives such as 
 carbohneum, crude oil, and various coal-tar products sold under 
 a variety of trade names, but the exact amount of which is 
 unknown. 
 
 ' American Wood Preservers' Association Proceedings, 1913. 
 
260 THE PRESERVATION OF STRUCTURAL TIMBER 
 
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APPENDICES 261 
 
 About 4,000,000 feet of lumber are also given a "fireproof" 
 treatment each year. 
 
 LIST OF COMPANIES IN THE UNITED STATES EQUIPPED 
 TO BUILD WOOD-PRESERVING PLANTS 
 
 Allis-Chalmers Co Milwaukee, Wis. 
 
 Basshor T. C. Co Baltimore, Md. 
 
 Bovaird & Seyfaud Mfg. Co Bradford, Pa. 
 
 Casey & Hedges Chattanooga, Tenn. 
 
 Chicago Bridge & Iron Co Chicago, IH. 
 
 Coeur d'Alene Iron Works Wallace, Idaho. 
 
 Cole, R. D Newan, Ga. 
 
 Erie Heating Co Chicago, 111. 
 
 Fairbanks Morse Co St. Paul, Minn. 
 
 Graves (Wm.)Tank Works East Chicago, Ind. 
 
 Gravier Tank Works Galveston, Tex. 
 
 Jacobs (S.) & Sons Birmingham, Ala. 
 
 Lockett (A.M.) & Co New Orleans, La. 
 
 Logan Iron Works Brooklyn, N. Y. 
 
 Manitowoc Engineering Works Manitowoc, Wis. 
 
 Mine-Smelter Supply Co Denver, Colo. 
 
 Mohr (John) & Sons Chicago, 111. 
 
 Moran Bros Seattle, Wash. 
 
 Morris Sherman Mfg. Co Chattanooga, Tenn. 
 
 National Boiler & Sheet Iron Works Indianapolis, Ind. 
 
 Payne & Joubert New Orleans, La. 
 
 Petroleum Iron Works Sharon, Pa. 
 
 Power & Mining Machinery Co Milwaukee, Wis. 
 
 Reeves Bros. Co Alliance, Ohio. 
 
 Struther- Wells Co Warren, Pa. 
 
 Union Iron Works San Francisco, Cal. 
 
 Vogt (Henry) Louisville, Ky. 
 
 WiUiamette Iron & Steel Works Portland, Ore. 
 
 Specifications for the Analysis of Creosote. — A number of speci- 
 fications for analyzing creosote oil have been proposed and are in 
 force. Perhaps the best known and the one in most extended use 
 is that adopted by the American Railway Engineering Associa- 
 tion, which reads as follows : 
 
 Specifications toe Analysis of Creosote Oil Approved 
 BY THE American Railway Engineering Association 
 
 1. The sample taken for analysis shall be strictly average of the 
 whole bulk of oil to be tested. The oil shall be completely 
 
262 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 liquefied and well mixed before samples are taken. Whenever 
 possible a drip sample of not less than 2 gallons shall be taken 
 commencing after the oil has started to run freely. When this 
 cannot be done, as for instance, in large storage tanks, samples 
 shall be taken from various depths in the tank by means of 
 a tube or bottle, the number of samples depending on local 
 conditions. 
 
 For taking samples during the process of treatment a 
 sample of the oil shall be taken from the storage tank about 1 
 foot from the bottom of the tank before the cylinder is filled, and, 
 where possible, a sample directly from the cylinder during the 
 process of treatment. For this purpose a thermometer well 
 may be used. 
 
 The sample to be analyzed shall be thoroughly Uquefied by 
 heating until no crystals adhere to a glass stirring rod, and also 
 well shaken, after which one-half shall be taken for analysis and 
 the balance reserved as check test. 
 
 2. The apparatus for distilhng the creosote shall consist of a 
 stoppered glass retort similar to that shown in diagram having 
 a capacity as nearly as can be obtained of 8 ounces up to the 
 bend of the neck when the bottom of the retort and the mouth 
 of the off-take are in the same plane. A nitrogen filled mercury 
 thermometer of good standard make, divided into full degrees 
 Centigrade, shall be used in connection therewith. In order to 
 insure uniform results for comparative purposes, the length of 
 the thermometer bulb shall be one-half (1/2) inch; but in no case 
 shall a thermometer with a long bulb be used. The bulb of the 
 retort and at least two (2) in. of the neck shall be and remain 
 covered with a shield of heavy asbestos paper, shaped as shown 
 in diagram, during the entire process of distillation, so as to 
 prevent heat radiation, and between the bottom of the retort and 
 the flame of the lamp or burner two sheets of wire gauze, each 
 20-mesh fine, and at least 6 inches square, shall be placed. 
 
 The flame shall be protected against air currents. An ordi- 
 nary tin can, from which a portion of the bottom and all of the top 
 have been removed, placed on a support attached to the burner, as 
 shown in diagram, will answer the purpose. 
 
 3. Before begiiming the distillation the retort shall be care- 
 fully weighed and exactly 100 grapas of oil placed therein, 
 the same being weighed in the retort. The thermometer 
 shall be inserted in the retort with the lower end of the bulb 
 
APPENDICES 263 
 
 1/2 inch froa the surface of the oil and the condensing tube 
 attached to the retort by a tight cork joint. The distance be- 
 tween the bulb of the thermometer and the end of the condensing 
 tube shall not be less than 20 nor Inore than 24 inches, and 
 during the progress of the distillation the thermometer shall 
 remain in the position originally placed. 
 
 The distillate shall be collected in weighed bottles and all 
 fractions determined by weight. Reports shall be "made on the 
 following fractions: 
 
 to 170° C. 235 to 270° C. 
 
 170 to 200° C. 270 to 315° C. 
 
 200 to 210° C. 315 to 355° C. 
 
 210 to 235° C. Residue above 355° C. 
 
 Reports shall be made on individual fractions. In making 
 such reports it is to be distinctly understood that these frac- 
 tions do not necessarily refer to individual cohapounds. In other 
 words, the fraction between 210 and 235° will not neces- 
 sarily be all naphthalene, but will probably contain a number of 
 other compounds. 
 
 The distillation shall be a continuous one, and should require 
 about 45 minutes. 
 
 When any measurable quantity of water is present in the oil 
 the distillation shall be stopped, the oil separated from the water 
 and returned to the retort, when the distillation shall be re- 
 commenced and the previous readings discarded. In obtaining 
 water-free oil, it is desirable to free about 300 to 600 c.c. of the oil 
 by using a large retort and using 100 grams of the water-free oil 
 for the final distillation. In the final report as to fractions, 
 a correction shall be made of the amount of water remaining, so 
 that the report may be "made on the basis of dry oil. 
 
 4. In order to determine the specific gravity of any oil, simply 
 heat the oil in a water bath until it is completely liquid. A 
 glass stirring rod dipped into the liquid should show no solid 
 particle on the rod when the same is withdrawn from the oil. 
 When completely liquid, it should be stirred thoroughly and the 
 hydrometer cylinder filled, which has previously been warmed. 
 Insert a specific gravity hydrometer of good make, taking care 
 that the hydrometer does not touch the sides or bottom of the 
 cylinder when the reading is taken. This reading should prefer- 
 ably be taken when the oil is at 38° C. (100° F.), because 
 
264 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 at this temperature almost all oils are completely fluid. 
 Where contract requirements specify a specific gravity at a dif- 
 ferent temperature, such gravity is obtained by multiplying 
 0.0008 by the number of degrees Centigrade, or 0.00044 by the 
 number of degrees Fahrenheit, the oil is found to be above the 
 temperature required by the contract, and adding the product to 
 the observed gravity. 
 
 If it is desired to ,make ftirther chemical analysis for the 
 detertnination of the low- boiling tar acids and the naphthalene, 
 the following method is recommended, tentatively: 
 
 "For the determination of low-boihng tar acids, the fractions 
 should be placed in a separating funnel, to which should be added 
 about 30 c.c. of the 15 percent hot sodium hydroxide solution, 
 vigorously shaken, and allowed to stand until the dissolved 
 phenols separate out and may be drawn off, after which repeat 
 with successive sodium hydroxide solutions 20 c.c. each time until 
 no phenols are left (the sodium solution comes off clear). The 
 phenols so obtained should be separated by the addition of a 25 
 percent sulphuric acid, slowly stirred in. When this reaction is 
 complete, the phenols so obtained should be decanted and 
 weighed." 
 
 The Committee on Wood Preservation of the National Electric 
 Light Association was not entirely satisfied with the above speci- 
 fications for analysis and drew up a set of its own.^ In the opin- 
 ion of this committee the above specification does not fully meet 
 present requirements because "it is generally admitted by chem- 
 ists that the retort is an antiquated piece of apparatus," and fur- 
 thermore the test is not sufficiently stringent to detect adultera- 
 tions. The specification for analysis which this committee rec- 
 ommended reads as follows: 
 
 ANALYSIS SPECIFICATIONS (NATIONAL ELECTRIC LIGHT 
 ASSOCIATION) 
 
 General 
 
 "The apparatus employed in making the distillation and other 
 tests required under these specifications shall conform in general 
 to that shown on drawings Fig 26 (Fig. No. a) and Fig. 27 at- 
 tached to and forming a part of these specifications, except that 
 a five percent (5%) variation from the dimensions given is 
 
 1 Report of Committee on Preservative Treatment of Poles and Cross 
 Arms, National Electric Light Association, 1911. 
 
APPENDICES 
 
 265 
 
 allowed. The distilling apparatus must be assembled as in draw- 
 ing Pig 28. As further defining the requirements in this re- 
 spect, the following description of certain parts and manner of 
 assembling is given: 
 
 (a) Flask. — The flask required is a Lunge side neck distilling 
 flask, provided with a trap (Fig. 26), and having a tubular 
 side neck thirty centimeters (30 cm.) long placed close to the 
 bulb. The flask must have a capacity of three hundred cubic 
 
 Dlatilling Flask 
 (PullSizel 
 
 Support for Flask 
 (Half Size) 
 
 Thermometer 
 
 Fig. 26. 
 
 Fig. 27. 
 
 centimeters (300 c.c.) when filled to a height equal to its maximum 
 horizontal diameter. 
 
 (6) Thermometer. — The thermometer must be made of Jena 
 glass and be nitrogen filled and graduated at intervals of one 
 millimeter (1 mm.) in single degrees Centigrade, the scale reading 
 to plus four hundred degrees Centigrade (-f 400° C). 
 
 (c) Receivers. — The glass receivers may be of any convenient 
 size and shape; the flask shown on drawing No. 114 is, however, 
 recommended. 
 
266 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 (d) Shield. — A shield ten centimeters (10 cm.) in diameter 
 and eight centimeters (8 cm.) high, made of asbestos, must 
 be provided (Fig. 27). 
 
 (e) Support for Flash. — The flask must rest on an asbestos 
 board one-half centimeter (0.5 cm.) in thickness by fifteen centi- 
 meters (15 cm.) in diameter, a hole iive centimeters (5 cm.) in 
 diameter being cut in the center of the board. The board shall 
 rest on a ring stand (Fig. 27). 
 
 ASSEMBLING APPARATUS 
 
 The apparatus must be assembled as shown in figure No. 
 28. The thermometer passes through a cork in the top of the 
 
 Fig. 28. 
 
 flask and is so placed that the top of the bulb of the thermometer 
 is on a line with the bottom of the tubular outlet. The asbestos 
 shield is placed around the bulb of the flask and the flask mounted 
 on the asbestos board supported on the ring stand as shown on 
 drawing Fig. 28. 
 
 Distillation Test 
 
 Two hundred grams of the oil shall be used in the analysis, 
 this amount being weighed on a balance sensitive to one milligram 
 (1 mg.), in the following manner: 
 
APPENDICES 267 
 
 The flask is first placed on the pan of the balance and weighed, 
 and the weight recorded. Without' removing the flask, a two 
 hundred (200) gram weight is placed on the opposite pan of the 
 balance and a sufficient quantity of the oil dropped into the 
 flask through a long stem funnel to bring the pans into equi- 
 librium. The flask is then removed from the balance and set up 
 as in drawing Fig. 28. Care must be taken that the cork 
 stopper carrying the thermometer fits tightly into place. The 
 flask should be heated, preferably by a Bunsen or other standard 
 form of gas burner. The distillation shall be continuous and 
 at such a rate that two (2) drops of oil per second (5 c.c. per 
 minute) leaves the end of the tubular after the thermometer 
 registers two hundred and five degrees Centigrade (205° C), 
 or after all of the water has been driven off. The percentage 
 weights of the following fractions shall be recorded : 
 
 To 205° C. 
 To 235° C. 
 To 245° C. 
 To 270° C. 
 To 315° C. 
 To 360° C. 
 
 DETERMINATION OF FREE CARBON 
 
 The apparatus required is as follows : 
 Knorr Condenser. 
 Knorr Flask. 
 
 C. S. & S. No. 575 Filter Papers, 15 cm. diajneter. 
 Wire for supporting filter papers. 
 Ten grams of the oil should be weighed into a small beaker 
 and digested with C. P. toluol on a steam bath. A cylindrical 
 filter cup is prepared by folding two of the papers around a rod 
 about five-eights of an inch (5/8") in diameter. The inner 
 paper should be cut to fourteen centimeters (14 cm.) diameter. 
 Prior to using the filter papers, they should have been extracted 
 with benzol to render them fat free. The filter cup is dried at 
 one hundred (100) to one hundred and ten (110) degrees 
 Centigrade and weighed in a weighing bottle. 
 
 The contents of the beaker are now decanted through the 
 filter cup, and the beakf washed with hot toluol, passing all 
 washings through the cup. "^he filtrate should be passed through 
 
268 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 the filter a second time, the residue washed two or three times 
 with hot C. P. benzol and transferred to the exti action ap- 
 paratus, in which C. P. benzol is used as the solvent, which 
 solvent is vaporized by means of a steain or water bath. The 
 extraction is continued until the filtrate is colorless. The filter 
 cup is then removed, dried and weighed in the weighing bottle. 
 C. P. benzol followed by chloroform may be used instead of 
 C. P. toluol followed by C. P. benzol. 
 
 Precautions. — In removing filter paper from the extraction 
 apparatus see that no particles of mercury find their way into the 
 precipitate. To prevent splashing, the filter paper should be 
 elevated as near to the outlet of the condenser as possible. A 
 good precaution is to cover the top of the filter cup with a round 
 cap of filter paper. 
 
 Sulphonation Test 
 
 Ten cubic centimeters (10 c.c.) of the total distillate to three 
 hundred and fifteen degrees Centigrade (315° C.) are placed 
 in a flask and warmed with four (4) to five (5) volumes of con- 
 centrated sulphuric acid to sixty degrees Centigrade (60° C.) and 
 the whole transferred to a graduated separatory funnel. The 
 flask is rinsed three times with small quantities of concentrated 
 sulphuric acid and the rinsings added to the contents of the 
 funnel, which is then stoppered and shaken, cautiously at first, 
 afterward vigorously, for at least fifteen (15) minutes and al- 
 lowed to stand over night. The acid is then carefully drawn 
 down into the graduated portion of the funnel to within two 
 cubic centimeters (2 c.c.) of where the unsulphonated residue 
 sho*ws. If no unsulphonated residue is visible the acid should 
 be drawn down to two cubic centimeters (2 c.c). In either case 
 the test should be carried further as follows: Add about twenty 
 cubic centimeters (20 c.c.) of water and allow to stand for 1/2 
 hour. Then draw off the water as close as possible without 
 drawing off any supernatant oil or emulsion, and ten cubic 
 centimeters (10 c.c.) of strong sulphuric acid and allow to stand 
 for from fifteen to twenty (15 to 20) minutes. Any unsulphonated 
 residue will now separate out clear and give a distinct reading. 
 If under two-tenths of a cubic centimeter (0.2 c.c.) it should be 
 drawn down into the narrow part of the funnel to just above 
 the stop-cock, where it can be estimated to one one-hundredth 
 of a cubic centimeter (0.01 c.c.) The volume of residue thus 
 obtained is calculated to the original oil." 
 
APPENDICES 269 
 
 DETERMINATION OF TAR ACIDS 
 
 One hundred cubic centimeters (100 c.c.) of the total distillate 
 to three hundred and fifteen degrees (315° C), to which forty- 
 cubic centimeters (40c. c.) of a solution of sodium hydroxide having 
 a specific gravity of one and fifteen hundredths (1.15) is added, is 
 warmed slightly and placed in a separatory funnel. The mixture 
 is vigorously shaken, allowed to stand until the oil and soda solu- 
 tions separate and the soda solution containing most of the tar 
 acids diawn oif. A second and third extraction is then made 
 in the same manner, using thirty (30) and twenty (20) cubic centi- 
 meters of the soda solution, respectively. The three alkaline 
 extracts are united in a two hundred cubic centimeter (200 c.c.) 
 graduated cylinder and acidified with dilute sulphuric acid. The 
 mixture is then allowed to cool and the volume of tar acids noted. 
 The results shown should be calculated to the original oil. 
 
 COKE TEST 
 
 In making the coke determination, hard glass bulbs are to be 
 used. The test is to be carried out as follows : 
 
 Warm the bulb slightly to drive off all moisture, cool in a 
 desiccator and weigh. Again heat the bulb by placing it momen- 
 tarily in an open Bunsen flame and place the tubular side neck 
 underneath the surface of the oil to be tested and allow the bulb 
 to cool until sufficient oil is sucked in to fill the bulb about two- 
 thirds full. Any globules of oil sticking to the inside of the tubu- 
 lar should be drawn into the bulb by shaking or expelled by slight- 
 ly heating it, and the outer surface should be carefully wiped off 
 and the bulb re- weighed. This procedure will give about one gram 
 of oil. Cut a strip of thin asbestos paper about one-quarter inch 
 wide and about 1 inch long, place it around the neck of the bulb and 
 catch the two free ends close up to the neck with a pair of crucible 
 tongs. The oil should then be distilled off as in making an ordi- 
 nary oil distillation, starting with a very low flame and conducting 
 the distillation as fast as can be maintained without spurting. 
 When oil ceases to come over, the heat should be increased 
 until the highest temperature of the Bunsen flame is attained, the 
 whole bulb being heated red hot until evolution of gas ceases 
 and any carbon sticking to the outside of the tubular is completely 
 burned off. The bulb should then be cooled in a desiccator and 
 weighed and the percentage of coke residue calculated to water - 
 free oil. 
 
270 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 Still" more refined specifications for analyzing creosote oil, 
 especially as regards the method of distillation and sulphonation 
 residues, are those in use by the U. S. Forest Service. In the 
 author's opinion these tests are much more exact than either of 
 the two just given. They are, however, more troublesome and 
 hence expensive to make, but where accuracy is desired, their use 
 is recommended. 
 
 Specifications FbR Analyzing Cbeosote Used by the 
 U. S. FoBEST Sebvice 
 
 {Note. — All temperatures referred to in the following are on 
 the centigrade scale.) 
 
 SPECIFIC GRAVITY OF THE WHOLE OIL 
 
 "The perfectly liquefied oil is poured into a hydrometer cylinder, 
 and, at a temperature of 60°, the specific gravity is read with 
 hydrometer standardized against water at 60°. 
 
 The somewhat prevalent method of determining specific 
 gravity with a hydrometer standardized at 15° and then calculat- 
 ing the results from the temperature of the determination back 
 to 15° is roundabout and involves the expression of the specific 
 gravity, of creosote in the liquid condition at a temperatuie at 
 which the oil does not exist as a liquid. The method is illogical 
 and open to inaccuracies. With very rare exceptions creosotes 
 are all liquid at 60°, and if the weight of a unit volume of the oil 
 at 60° is compared with the weight of a unit volume of water at 60°, 
 a true specific gravity is obtained. . . . 
 
 FRACTIONAL DISTILLATION 
 
 The Hempel distilling flask of resistance glass is employed. 
 The empty flask is tared, 250 grams of melted, well-shaken oil 
 introduced, the platinum- wire plug and the glass beads put in 
 place, and a second weight taken. The thermometer is then 
 inserted in the flask, so that the first emergent reading is 200°. 
 The flask is supported on an asbestos board with a slightly ir- 
 regular opening of very nearly the largest diameter of the flask. 
 A condensing tube is employed and the fractions are collected in 
 
 ' Circular 206, United States Forest Service. 
 
APPENDICES 271 
 
 taied flasks. The distillation is run at the rate of 1 drop per 
 second, and fractions collected between the following tempera- 
 tures: Up to 170°, 170°-205°, 205°-225°, 225°-235°, 235°-245°, 
 245°-255°, 255°-285°, 285°-295°, 295°-305°, 305°-320°, and if 
 feasible, 320°-360°. 
 
 The characters of the fractions and their weights are recorded 
 and the results plotted as a curve, in which the ordinates are per- 
 centages by weight and the abscissae temperatures. . . . 
 When the distillation has reached the 225° point, an asbestos- 
 board box should be placed around the distilling flask, to cover 
 the bulb, but leave the Hempel column exposed. Drafts upon 
 the distilling apparatus must be avoided. 
 
 INDEX OF REFRACTION 
 
 The indices of refraction of the different fi actions between 235° 
 and 305° are determined at 60° in a refractometer with light 
 compensation. The results are plotted with temperatures as 
 abscissae and indices of refraction as ordinates. 
 
 "index of Refraction. — The index of refraction is the ratio between the 
 sines of the angles of incidence and of refraction of light, expressed by the 
 
 formula "f; = ~ s' where -h means the index of refraction referred to 
 
 D sme it U 
 
 sodium light, I equals the angle of incidence, and R the angle of refraction. 
 The index of refraction varies with the temperature, but is constant for 
 any given oil at a stated temperature. In makiag measurements of the 
 index of refraction of the different fractions of a creosote distillation, it was 
 necessary to make the measurements at 60°. The determinations were 
 made with an Abbe refractometer provided with a light compensator. By 
 means of this instrument the index of refraction may be read with great 
 accuracy, and the measurement is one of the most exact which can be 
 applied to such an oU. 
 
 "Sulphonation Test. — In contradistinction to the hydrocarbons of the 
 paraffin series, those of the aromatic series react with concentrated sulphuric 
 acid with marked ease. The products of this reaction, in which a sulpho 
 group or groups replace hydrogen in the aromatic compound, are called 
 sulphonic acids and the process is known as sulphonation. For example, 
 the reaction with benzene would be CeHe + HzS04 = CeHsSOsH + H2O. 
 The sulphonic acids are characterized by their solubility ia water. If a 
 fraction from the distillation of a creosote oil be treated under proper con- 
 ditions with concentrated sulphuric acid, it will be converted into a mixture 
 of sulphonic acids, which will readily dissolve in water. If, however, there 
 are paraffin bodies present they wUl not be attacked to the same degree as 
 
 1 The following explanation of the index of refraction and of the sulphona- 
 tion test is taken from U. S. Forest Service Circular 112: 
 
272 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 the aromatic hydrocarbons, and when the products of the sulphonation are 
 treated with water the paraffin components will remain as a residual oil. 
 In applying this test to creosote oils it has been found that the most 
 information is obtained by using it on the higher boiling fractions." 
 
 Specific Gravity. — The specific gravities of the fractions 
 between 235° and 305° are determined by means of specific- 
 gravity bottles. These bottles are filled at 60° and the weights 
 referred to water at the same temperature. The results are 
 plotted as a curve in which the ordinates are specific gravities 
 at 60° and the abscissae temperatures. 
 
 Sulphonation Tests.^ — Ten cubic centimeters of the fraction of 
 creosote to be tested are measured into a Babcock milk bottle. 
 To this is added 40 c.c. of 37 times normal acid, 10 c.c. at a 
 time. The bottle with its contents is shaken for 2 minutes after 
 each addition of 10 c.c. of acid. After all the acid has been 
 added the bottle is kept at a constant temperature of from 98° 
 to 100° C. for 1 hour, during which time it is shaken vigoiously 
 every 10 minutes. At the end of an hour the bottle is re- 
 moved, cooled, and filled to the top of the graduation with ordi- 
 nary sulphuric acid, and then whirled for 5 minutes in a Babcock 
 separator. The unsulphonated residue is then read off from the 
 graduations. The leading multiplied by 2 gives pfercent by vol- 
 ume directly. (Each graduation equals one two-hundredth of a 
 cubic centimeter.) 
 
 In well-equipped chemical laboratories the usual steam-jacket 
 ovens, capable of maintaining a temperature of from 98° to 100° 
 C, will keep the reaction mixture of the sulphuric acid and creo- 
 sote at the proper temperature. It frequently happens, however, 
 that creosotes are analyzed in a laboratory equipped only for that 
 purpose, and for such cases a special steam bath or oven can be 
 made by any tinsmith at small cost. It is essential that the 
 chamber be of sufficient size to completely contain (under the 
 cover) the Babcock bottle; otherwise the exact dimensions of the 
 steam bath are unimportant, and any two vessels of suitable di- 
 mensions, which are at hand or can most readily be obtained, may 
 be utilized in its construction. 
 
 Tar Acids. — Fifty cubic centimeters of the creosote under analy- 
 sis are measured at 60° into a small distilling flask by a pipette. 
 The oil is distilled as completely'as possible without breaking the 
 distilling bulb, and the distillate is caught in a short-stemmed 
 
 ' U. S. Forest Service Circular 191. 
 
APPENDICES 273 
 
 100 c.c. separating funnel. At the end of the distillation 25 
 c.c. of boiling hot 15 percent sodium hydroxide are added to 
 the distillate and the mixture thoroughly shaken. The alkaline 
 extract is then drawn off into a 100 c.c. cylinder and 25 c.c. 
 more of hot sodium hydroxide added. After extracting with 
 this second portion for 5 minutes, with frequent shaking, the 
 solutions are allowed to separate and the alkaline extract added 
 to the first portion in the cylinder. A third extraction is made 
 with 15 c.c. of alkali. The total alkaline extract is cooled, 
 acidified with sulphuric acid, thoroughly shaken, brought to 60°, 
 and the volume of supernatant oil read off. 
 
 Water. — ^After weighing the first two fractions of a fractional 
 distillation they are united in a small separatory funnel and any 
 water which is present is separated frotn the oil and its amount 
 accurately determined. If particular accuracy is required in 
 the estimation of the water it may be done by the Marcusson xylol 
 distillation method.^" 
 
 METHOD FOR DETERMINING THE AMOUNT OF MOISTURE IN 
 CREOSOTE AND CREOSOTED WOOD 
 
 "The creosoted wood, in the form of borings, turnings, saw- 
 dust, or similar material, is quickly weighed and transferred to 
 the 250 c.c. Erlenmeyer flask, and 75 c.c. of water-saturated 
 xyloP added. The basin in which the flask is placed should 
 be two-thirds full of melted paraflin or of some heavy lubricat- 
 ing oil such as cylinder oil. The bath is heated and the distil- 
 lation continued until the distillate comes in clear drops. At 
 the end of the distillation the condenser should be rinsed with 
 the stream from a wash bottle containing xylol. After it has 
 stood for a short time, the emulsion of water and xylol separates, 
 giving two clear liquid layers. The mean of the readings at the 
 top and bottom of the meniscus, between xylol and water, gives 
 the volume of water, and the percentage of moisture in the 
 wood is obtained by multiplying the water volume by 4. There 
 are always small globules of water adhering to the sides of the 
 graduate in the portion filled with xylol. These are readily 
 
 ' Forest Service Circular 134, The Estimation of Moisture in Creosoted 
 Wood, A. L. Dean. 
 
 ^ Water-saturated xylol is readily prepared by heating a mixture of water 
 and xylol with frequent shakings and subsequently removing the water in a 
 separatory funnel. 
 18 
 
274 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 scrubbed down with a piece of rubber tube on the end of a piece 
 of glass tubing, which is better for this purpose than the rod com- 
 monly used for a "policeman." 
 
 It is important that the distillation be carried on slowly to 
 allow all the water in the wood to volatilize. The finer the wood 
 particles, the more rapid may be the distillation. If rather 
 coarse material is used, the distillation should not run faster than 1 
 drop per second. 
 
 The" apparatus shown in Fig. 29 was devised for making 
 large numbers of moisture estimations on creosoted wood. The 
 
 Fig. 29. — Apparatus for making several moisture determinations in 
 
 creosoted wood. 
 
 compartments of the paraffin bath are larger than necessary for 
 the 260 c.c. flasks, but the apparatus was designed so that larger 
 flasks might be employed when considerable wood was to be used, 
 for purposes of investigation, to obtain very accurate results. 
 
 Marcusson's method is well adapted to the estimation of water 
 in creosote oils. The apparatus used for creosoted wood is satis- 
 factory for creosote, except that a wire gauze should be sub- 
 stitute for the paraffin bath. The 250 cubic centimeter flask 
 is weighed, 50 cubic centimeters of melted, well-shaken creosote 
 introduced, and a second weight taken. Seventy-five cubic 
 centimeters of water-saturated xylol are added and the mixture 
 distilled until the water ceases to come off. The percentage of 
 water is obtained by dividing the volume (cubic centimeters) 
 of water in the distillate by the weight (grams) of creosote. The 
 results are likely to run one or two-tenths of a percent too low. 
 
APPENDICES 
 
 275 
 
 THE DURABILITY OF AMERICAN TIMBERS 
 
 The durability of timber is so exceedingly variable that any 
 general table is of value solely in securing an approximate idea of 
 the durability of one wood as compared with another — and not 
 as an index of what the wood will actually do under all con- 
 ditions. For example, timber used in the South and exposed to 
 the weather will decay quicker than the same timber placed under 
 similar conditions in the North; timber cut from a given tree 
 may be more durable than timber cut from the same kind of 
 a tree which grew next to it; timber placed in one kind of soil 
 may be far more durable than the same timber placed in another 
 soil, etc. All of these variations have been discussed in the 
 preceding chapters. Taking all of them into consideration and 
 striking an average for common practice. Table 40 has been 
 compiled. It naturally follows that these figures are of chief 
 value in comparing the relative durability of one kind of 
 untreated wood with another, and it is believed that most of them 
 are approximately correct. As more authentic data is collected, 
 it is quite likely that changes in the estimated durability will be 
 necessary. 
 
 Table 40. — The Estimated Dukability of Untreated Wood in Contact 
 
 With the Soil 
 
 Class A. — Very durable 
 
 Class B. — Durable woods. 
 
 Class C. — Nondurable woods. 
 
 woods. 
 
 (These woods will probably 
 
 last more than 25 years 
 
 (These woods willprobably 
 last more than 10 years but 
 less than 25 years in contact 
 
 (These woods will probably 
 last less than 10 years in 
 contact with the soil) 
 
 in contact with the soil) 
 
 with the soil) 
 
 
 Black locust 
 
 Chestnut 
 
 Aspen 
 
 Northern white cedar 
 
 Southern white cedar 
 
 Ash 
 
 Western red cedar 
 
 Douglas fir 
 
 Beech 
 
 Cypress 
 
 Red gum (heart) 
 
 Bhch 
 
 Mulberry 
 
 White oaks 
 
 Basswood 
 
 Osage orange 
 
 Longleaf pine 
 
 Balsam 
 
 Redwood 
 
 
 Cottonwood 
 
 Elm 
 
 Red gum (sap) 
 
 Blue gum 
 
 Hemlock 
 
 Red oaks 
 
 Western yellow pine 
 
 Lodgepole pine 
 
 Loblolly pine 
 
 Sitka spruce 
 
 White spruce 
 
 Sycamore 
 
 Tamarack 
 
 Tupelo 
 
276 THE PRESERVATION OF STRUCTURAL TIMBER 
 List of U. S. Patents on Wood Preservation 
 
 Name and address of 
 inventor 
 
 Title of patent 
 
 No. of 
 patent 
 
 Date issued 
 
 Henry Aitken, Darrooh, 
 Falkirk, Scotland 
 
 Preserving timber. 
 
 352,216 
 
 Nov. 9, 1886 
 
 Hugo Akerhielm, Chicago, 
 111. 
 
 Improvement in compositions for 
 preserving wood. 
 
 185,058 
 
 Deo. 5, 1876 
 
 Augustus, Allen, Cass Co., 
 Mich. 
 
 Improved method of preventing 
 decay in the timbers of bridges, 
 buildings, etc. 
 
 106,647 
 
 Aug. 23, 1870 
 
 Edw. R. Andrews, New 
 York, N. Y. 
 
 Composition for preserving wood. 
 
 247,234 
 
 Sept. 20, 1881 
 
 W. C. Andrews, New 
 York, N. Y. 
 
 Vulcanizing wood. 
 
 430,055 
 
 June 10, 1890 
 
 Philip F. Apfel, Seattle, 
 Wash, and Ralph L. Earn- 
 est, Portland, Ore. 
 
 Protecting piles against worms, etc. 
 
 883,507 
 
 Mar. 31, 1908 
 
 Oliver App, Blue Mound, 
 111. 
 
 Improvement in compositions for 
 preserving wood. 
 
 219,377 
 
 Sept. 9, 1879 
 
 R. W. Archer, Corpus 
 Christi, Tex. 
 
 Improvement in processes for pre- 
 serving wood. 
 
 153,515 
 
 July 28, 1874 
 
 MoKenzie Arnn, Bristol, 
 Va. 
 
 Composition for coloring and pre- 
 serving wood. 
 
 601,767 
 
 Apr. 5, 1898 
 
 McKenzie Arnn, Bristol, 
 Va. 
 
 Wood preserving compound. 
 
 633,778 
 
 Sept. 26, 1890 
 
 Chas. Arnoudts, Seattle, 
 Wash. 
 
 Composition for preserving piles 
 from teredo, etc. 
 
 526,552 
 
 Sept. 25, 1894 
 
 Max Bachert, New York, 
 
 N. Y. 
 
 Apparatus for saturating wood. 
 
 666,915 
 
 Jan. 29, 1901 
 
 Max Bachert, New York, 
 N. Y. & D. W. O'Neil, 
 Newark, N. J. 
 
 Preserved wood and process of pre- 
 paring same. 
 
 602,713 
 
 Apr. 19, 1898 
 
 Thurman Bailey, Brid- 
 port, Vt. 
 
 Improvement in processes for pre- 
 paring wood for roofing. 
 
 125,251 
 
 Apr. 2, 1872 
 
 Jas. J. Barr, Slidell, La. 
 
 Automatic retort-cover. 
 
 857,148 
 
 June 18, 1907 
 
 Jaa. R. Bate, Cincinnati, 
 Ohio. 
 
 Process of preserving wood. 
 
 522,284 
 
 July 3, 1894. 
 
 Frank Batter, Marshfield, 
 Ore. 
 
 Apparatus for preserving piles. 
 
 452,513 
 
 May 19, 1891 
 
 J. H. Bauer, Scranton, Pa. 
 
 Improvement in processes for treat- 
 ing sounding-boards. 
 
 149,426 
 
 Apr. 7, 1874 
 
 S. Beer, New York, N. Y. 
 
 Improved process for seasoning and 
 preserving wood. 
 
 73,565 
 
 Jan. 21, 1868 
 
APPENDICES 
 List of U. S. Patents on Wood Preservation. — Continued 
 
 277 
 
 Nane and address 
 inventor 
 
 Title of patent 
 
 No. of 
 patent 
 
 Date issued 
 
 Andries Bevier, New York, 
 N. Y. 
 
 Method of preserving wood. 
 
 681,032 
 
 Aug. 20, 1901 
 
 V. W. Blanchard, Brid- 
 port, Vt. 
 
 Improved mode of preserving wood. 
 
 94,704 
 
 Sept. 14, 1869 
 
 Guido Blenio, New York, 
 
 N. Y. 
 
 Process for ^reproofing wood. 
 
 779,761 
 
 Jan. 10, 1905 
 
 A. T. Bleyley, Conception, 
 Mo. 
 
 Improvement in processes for pre- 
 serving burial oases, etc. 
 
 175,329 
 
 Mar. 28, 1876 
 
 H. H. Blodgett, Omaha, 
 Nebr. 
 
 Wood-preserving composition 
 
 606,702 
 
 July 5, 1898 
 
 John B. Blythe, Bordeaux, 
 France. 
 
 Treating railway-sleepers. 
 
 313,912 
 
 Mar. 17, 1885 
 
 John B. Blythe, Bordeaux," 
 France. 
 
 Apparatus for treating, seasoning 
 and preserving timber. 
 
 313,913 
 
 Mar. 17, 1885 
 
 John Borner, Rahway, 
 N.J. 
 
 Apparatus for impregnating wood. 
 
 703,522 
 
 July 1, 1902 
 
 S. B. Boulton, Cooped 
 HaU, County of Hertford, 
 England. 
 
 Treating timber with preservative 
 fluids. 
 
 247,602 
 
 Sept. 27, 1881 
 
 S. B. Boulton, London, 
 Eng. 
 
 Method of preserving timber. 
 
 360,947 
 
 Apr. 12, 1887 
 
 Edmond Bouvier, Pensa- 
 cola, Fla. 
 
 Improvement in solutions for pre- 
 serving timber. 
 
 218,659 
 
 Aug. 19, 1879 
 
 Joachim Brenner, Gain- 
 farn, Austria-Hungary. 
 
 Process of dyeing wood. 
 
 755,993 
 
 Mar. 29, 1904 
 
 Jas. P. Bridge, Boston, 
 Mass. 
 
 Improved compound for preserving 
 wood, leather, etc. 
 
 86,808 
 
 Feb. 9, 1869 
 
 Robert E. Bright, Gren- 
 ada, Miss. 
 
 Apparatus for treating timber. 
 
 887,583 
 
 May 12, 1908 
 
 H. R. Brinkerhoff, Oak- 
 park, 111. 
 
 Waterproofed wood and method of 
 making same. 
 
 686,582 
 
 Nov. 12, 1901 
 
 Albert Brisbane, New 
 York, N. Y. 
 
 Improvement in processes for treat- 
 ing wood for paving and other 
 purposes 
 
 155,788 
 
 Oct. 13, 1874 
 
 Wm. Brisley, and Wm. S. 
 Finch, Toronto, Canada 
 
 Composition for preserving wood. 
 
 359,384 
 
 Mar. 15, 1887 
 
 Chas. Brown, Albemarle 
 Co., Va. 
 
 ^Improved process of preserving tim-. 
 ber from decay. 
 
 83,758 
 
 Nov. 3, 1868 
 
278 THE PRESERVATION OF STRUCTURAL TIMBER 
 List of TJ. S. Patents on Wood Preservation. — Continued 
 
 Name and address of 
 inventor 
 
 Title of patent 
 
 No. of 
 patent 
 
 Date issued 
 
 Saml. P. Brown, WasMng- 
 ton, D. C. 
 
 Improvement in preserving wood. 
 
 115,931 
 
 June 13, 1871 
 
 W. C. Bruson, Chicago, 
 111. 
 
 Compound for preserving wood. 
 
 251,346 
 
 Dec. 27, 1881 
 
 Walter Buehler, Minne- 
 apolis, Minn. 
 
 Preserving wood. 
 
 899,237 
 
 Sept. 22, 1908 
 
 Walter Buehler, Minne- 
 apolis, Minn. 
 
 Preserving wood. 
 
 899,480 
 
 Sept. 22, 1908 
 
 Wm. W. Bunnell," Thomas- 
 ville, Nebr. 
 
 Compound for preserving wood. 
 
 238,341 
 
 Mar. 1, 1881 
 
 Peter Grant Burns, St. 
 Louis, Mo. 
 
 Wood-preserving apparatus. 
 
 864,092 
 
 Aug. 20, 1907 
 
 Rudolph G. Burstenbin- 
 der, Hamburg, Germany 
 
 Preservation of wood. 
 
 266,092 
 
 Oct. 17, 1882 
 
 Jas. J. Byers, Gulfport, 
 Miss. 
 
 Wood saturating and coating 
 apparatus. 
 
 858,950 
 
 July 2, 1907 
 
 Saml. Cabot, Jr., Boston, 
 
 Mass. 
 
 Improvement in processes for pre- 
 serving wood. 
 
 184,141 
 
 Nov. 7, 1876 
 
 Saml Cabot, Brookline, 
 Mass. 
 
 Compound for bleaching and pre- 
 serving wood. 
 
 515,191 
 
 Feb. 20, 1894 
 
 Jas. Calkins, New York, 
 N. Y. 
 
 Improvement in. preserving wood. 
 
 78,514 
 
 June 2, 1868 
 
 Jos. P. Card, Sf. Louis, 
 
 Mo. 
 
 Preserving wood. 
 
 254,274 
 
 Feb. 28, 1882 
 
 Jos. P. Card, St. Louis, 
 Mo. 
 
 Process of preserving wood. 
 
 317,440 
 
 May 5, 1885 
 
 J. P. Card, Chicago, 111. 
 
 Solution for preserving wood. 
 
 419,582 
 
 Jan. 14, 1890 
 
 Jos. B. Card, Chicago, 111. 
 
 Method of preserving wood. 
 
 815,404 
 
 Mar. 20, 1906 
 
 C. S. Chamberlain, Oak- 
 land, Cal. 
 
 Wood-preserving apparatus. 
 
 621,774 
 
 Mar. 21, 1899 
 
 Octave Chanute, Kansas 
 City, Mo. 
 
 Preserving timbered structures. 
 
 430,068 
 
 June 10, 1890 
 
 Octave Chanute, Chicago, 
 111. 
 
 Process of preserving wood. 
 
 688,932 
 
 Dec. 17, 1901 
 
 S. B. Chapman, Abbeville, 
 Ga. 
 
 Solution for preserving lumber. 
 
 764,913 
 
 July 12, 1904 
 
APPENDICES 
 List of U. S. Patents on Wood Preservation. — Continued 
 
 279 
 
 Name and address of 
 inventor 
 
 Title of patent 
 
 No. of 
 patent 
 
 Date issued 
 
 Sydney B. Chapman, Sky- 
 land, N. C. 
 
 Treated wood and process of pro- 
 ducing the same. 
 
 839,55] 
 
 Dec. 25,19 06 
 
 Emile Chevigny 
 
 Composition of matter for painting 
 and preserving wood. 
 
 824,794 
 
 July 3, 1906 
 
 William B. Chisholm 
 Charleston, S. C. 
 
 Preservation of wood. 
 
 802,680 
 
 Oct. 24, 1905 
 
 Chas. E. Clarke, Geo. 
 Hadley, and J. C. Clif- 
 ford, Buffalo, N. Y. 
 
 Improved mode of preserving wood. 
 
 67,104 
 
 July 23, 1867 
 
 E. W. Clark, Hartford, 
 Conn. 
 
 Improved solution for the treat- 
 ment of wood. 
 
 94,869 
 
 Sept. 14, 1869 
 
 Seth L. Cole, Brooklyn, 
 N. Y. 
 
 Improvement in preserving wood. 
 
 124,419 
 
 Mar. 12, 1872 
 
 Seth L. Cole, Brooklyn, 
 N. Y. 
 
 Improvement in processes of pre- 
 serving wood. 
 
 124,420 
 
 Mar. 12, 1872 
 
 Edw. Z. Collings, Camden, 
 N.J. 
 
 Apparatus for preserving wood. 
 
 310,880 
 
 Jan. 20, 1885 
 
 Edw. Z. Collings, Camden, 
 N.J. 
 
 Method of preserving wood. 
 
 317,730 
 
 May 12, 1885 
 
 Jos. H Connelly, Alle- 
 gheny, Pa. 
 
 Preserved wood. 
 
 243,062 
 
 June 21, 1881 
 
 Silas Constant, Peekskill, 
 N. Y. and John Smith, 
 Brooklyn, N. Y. 
 
 Improvement in seasoning and pre- 
 serving wood. 
 
 65,545 
 
 Mar. 17, 1867 
 
 Silas Constant, Peekskill, 
 and John Smith, Brook- 
 lyn, N. Y. 
 
 Improvement in seasoning and pre- 
 serving wood. 
 
 116,274 
 
 June 27, 1871 
 
 Geo. C. Cowles, Bay Mills, 
 Mich. 
 
 Undressed lumber and process of 
 preserving same. 
 
 746,678 
 
 Deo. 15, 1903 
 
 E. L. Cowling, Boston, 
 Mass. 
 
 Improvement in preserving wood. 
 
 84,733 
 
 Deo. 8, 1868 
 
 C. M. Cresson, Philadel- 
 phia, Pa. 
 
 Improvement in preserving wood. 
 
 79,554 
 
 July 7, 18.68 
 
 C. M. Cresson, Philadel- 
 phia, Pa. 
 
 Improvement in seasoning and pre- 
 serving wood. 
 
 109,872 
 
 Dec. 6, 1870 
 
 C. M. Cresson, Philadel- 
 phia, Pa. 
 
 Improvement in seasoning and pre- 
 serving wood. 
 
 109,873 
 
 Deo. 6, 1870 
 
 Wm. Cross, Brisbane, 
 Queensland. 
 
 Method of preserving timber. 
 
 643,762 
 
 Feb. 20, 1900 
 
280 THE PRESERVATION OF STRUCTURAL TIMBER 
 List of U. S. Patents on Wood Preservation. — Continued 
 
 Name and addresa of 
 inventor 
 
 Title of patent 
 
 No. of 
 patent 
 
 Date issued 
 
 W. G. Curtis, and J. D. 
 Isaacs, San Francisco, 
 Cal. 
 
 Process of preserving timber. 
 
 545,222 
 
 Aug. 27, 1895 
 
 W. G. Curtis, and J. D. 
 Isaacs, San Francisco, 
 Cal. 
 
 Process of preserving wood. 
 
 11,515 
 
 Dec. 3, 1895 
 
 A. R. Davis, Cambridge, 
 Mass. 
 
 Improved process of treating wood 
 for covering walla. 
 
 74,056 
 
 Feb. 4, 1868 
 
 Edw. Davis, Redondo, 
 Cal. 
 
 Pliable-flange pile-casing. 
 
 464,960 
 
 Dec. 15, 1891 
 
 J. C. Day, Hackettstown, 
 N. J. 
 
 Improvement in seaaoning and pre- 
 serving wood. 
 
 100,380 
 
 Mar. 1, 1870 
 
 J. A. Deghuee, New York, 
 N. Y. 
 
 Method of preaerving and water- 
 proofing wood. 
 
 802,739 
 
 Oct. 24, 1905 
 
 E. J. De Smedt, New 
 York, N. Y. 
 
 Improved composition for pre- 
 aerving timber and wood. 
 
 100,608 
 
 Mar. 8, 1870 
 
 B. H. Detwiler and 
 S. G. Van Gilder, Wil- 
 liamspoTt Fa. 
 
 Improvement in preaerving woods. 
 
 111,045 
 
 Jan. 17, 1871 
 
 Fred Dixon, Loudon, Eng. 
 
 Improvement in processes for treat- 
 ing wood. 
 
 181,651 
 
 Aug. 29,1876 
 
 B. V. B. Dixon and J. P. 
 Card, St. Louis, Mo. 
 
 Preserving wood. 
 
 239,033 
 
 Mar. 22, 1881 
 
 John Dolbeer, San Fran- 
 cisco, Cal. 
 
 Apparatus for steaming piles. 
 
 333,204 
 
 Dec. 29, 1885 
 
 H. C. Dorr, San Francisco, 
 Cal. 
 
 Compound for preserving wood. 
 
 293,955 
 
 Feb. 19, 1884 
 
 C. J. Doyle, Philadelphia, 
 Pa. 
 
 Apparatus for preserving wood. 
 
 645,793 
 
 Mar. 20, 1900 
 
 J. A. Draper, Shaftsbury, 
 Vt. 
 
 Improvement in compounds for 
 preserving wood. 
 
 152,620 
 
 June 30, 1874 
 
 Wm. Dripps, Coatesville, 
 Pa. 
 
 Improved process of restoring and 
 preaerving decaying railroad ties. 
 
 96,405 
 
 Nov. 2, 1869 
 
 P. H. Dudley, New York, 
 N. Y. 
 
 Apparatus for impregnating wood. 
 
 381,682 
 
 Apr. 24, 1888 
 
 P. H. Dudley, New York, 
 N. Y. 
 
 Preserving railway-ties. 
 
 406,566 
 
 July 9, 1889 
 
 Firmin Dufouric, New 
 York, N. Y. 
 
 Improvement in processes for pre- 
 serving wood. 
 
 150,841 
 
 May, 12 1874 
 
APPENDICES 
 List of U. S. Patents on Wood Preservation. — Continued 
 
 281 
 
 Name and address of 
 inventor 
 
 Title of patent 
 
 No. of 
 patent 
 
 Date issued 
 
 P. F. Dundon, San Fran- 
 cisco, Cal. 
 
 Timber-treating process. 
 
 753,052 
 
 Feb. 23, 1904 
 
 Chas. J. Eames, New 
 York, N. Y. 
 
 Improvement in processes for pre- 
 serving wood. 
 
 134,133 
 
 Dec. 24, 1872 
 
 Edw. Earle, Savannah, Ga. 
 
 Improvement in the mode of pre- 
 serving timber. 
 
 934 
 
 Sept. 20, 1838 
 
 H. F. Eclcert, San Fran- 
 cisco, Cal. 
 
 Apparatus for preserving timber. 
 
 509,724 
 
 Nov. 28, 1893 
 
 H. L. Eddy, Geneva, N. Y. 
 
 Improved method of preserving 
 wood. 
 
 53,217 
 
 Mar. 13, 1866 
 
 W. E. EverettB, Tacoma, 
 Wash. 
 
 Method of preserving wood. 
 
 801,859 
 
 Oct. 17, 1905 
 
 L. S. Fales, Monmouth 
 Junction, N. J. 
 
 Improvement in compounds for 
 preserving wood. 
 
 142,453 
 
 Sept. 2, 1873 
 
 H. W. Fawcett, Titusville, 
 Pa. and Thomson Mc- 
 Gowan, Meredith, Pa. 
 
 Improvement in preserving wood. 
 
 123,009 
 
 Jan. 23, 1872 
 
 J. S. George, Ferndale, 
 Wash. 
 
 Injecting apparatus. 
 
 765,312 
 
 July 19, 1904 
 
 Jos. L. Ferrell, Philadelphia, 
 Pa. 
 
 Method of and apparatus for fire- 
 proofing wood, etc. 
 
 620,114 
 
 Feb. 28, 1899 
 
 Jos. L. Ferrell.Philadelphia, 
 Pa. 
 
 Process of impregnating wood. 
 
 694,956 
 
 Mar. 11, 1902 
 
 Jos. L. Ferrell, Philadelphia, 
 Pa. 
 
 Process of impregnating wood with 
 fireproofing preservatives, etc. 
 
 695,450 
 
 Mar. 18, 1902 
 
 Jos. L. Ferrell, 
 Philadelphia, Pa. 
 
 Fireproofed wood and method of 
 of making same. 
 
 695,678 
 
 Mar. 18, 1902 
 
 Jos. L. Ferrell, 
 Philadelphia, Pa. 
 
 Fireproofing compound and method 
 of making same. 
 
 695,679 
 
 Mar. 18, 1902 
 
 Jos. L. Ferrell, 
 Philadelphia, Pa. 
 
 Apparatus for impregnating wood. 
 
 716,400 
 
 Deo. 23, 1902 
 
 Jos. L. Ferrell, 
 Philadelphia, Pa. 
 
 Apparatus for implregnating wood. 
 
 716,401 
 
 Dec. 23, 1902 
 
 Jos. L. Ferrell, 
 Philadelphia, Pa. 
 
 Apparatus for impregnating wood. 
 
 727,928 
 
 May 12, 1903 
 
 Jos. L. Ferrell, 
 Philadelphia, Pa. 
 
 Fireproof wood, etc., and the art of 
 making same. 
 
 728,452 
 
 May 19, 1903 
 
282 THE PRESERVATION OF STRUCTURAL TIMBER 
 List of U. S. Patents on Wood Preservation. — Continued 
 
 Name and address of 
 inventor 
 
 Title of patent 
 
 No. of 
 patent 
 
 Date issued 
 
 Joa. L. Ferrell, 
 Philadelphia, Pa. 
 
 Process of fireproofing wood. 
 
 767,514 
 
 Aug. 16, 1904 
 
 Lewis Feuohtwanger, 
 New York, N. Y. 
 
 Improvement in preserving wood. 
 
 123,467 
 
 Feb. 6, 1872 
 
 J. W. Fielder, 
 Princeton, N. J. 
 
 Improvement in apparatus for pre- 
 serving wood by the Robbins 
 Process. 
 
 115,946 
 
 June 13, 1871 
 
 Henry Flad, 
 St. Louis, Mo. 
 
 Method of seasoning wood. 
 
 231,783 
 
 Aug. 31, 1880 
 
 Henry Flad, 
 St. Louis, Mo. 
 
 Process of preserving wood. 
 
 231,784 
 
 Aug. 31, 1880 
 
 Henry Flad, 
 St. Louis, Mo. 
 
 Apparatus for the treatment of 
 timber for preserving it. 
 
 253,361 
 
 Feb. 7, 1882 
 
 Webster Flockton, 
 Bermondsey, Eng. 
 
 Inprovement in metallic solutions 
 tor the preservation of timber. 
 
 130 
 
 Feb. 16, 1837 
 
 H. P. Folsom, and Howard 
 Jones, Circleville, Ohio. 
 
 Sterilized erected pole. 
 
 837,820 
 
 Deo. 4, 1906 
 
 Henry Page Folsom and 
 Howard Jones, 
 Circleville, Ohio. 
 
 Sterilizing and preserving posts 
 and poles. 
 
 894,619 
 
 July 28, 1908 
 
 B. S. Foreman, 
 Morrison, 111. 
 
 Improvement in preserving wood, 
 railroad ties, etc. 
 
 43,191 
 
 June 21, 1864 
 
 B. S. Foreman, 
 
 Improvement in preserving wood, 
 railroad ties, etc. 
 
 4,360 
 
 May 2, 1871 
 
 E. M. Fowler, 
 New York, N. Y. 
 
 Improvement in preserving blocks 
 of wood. 
 
 112,136 
 
 Feb. 28, 1871 
 
 J. D. Franoks, 
 Hanover, Germany. 
 
 Process for preserving wood. 
 
 231,419 
 
 Aug. 24, 1880 
 
 Chas. S. Friedman, 
 Philadelphia, Pa. 
 
 Method of creosoting wood. 
 
 693,697 
 
 Feb. 18, 1902 
 
 Wm. T. Garratt, 
 
 San Francisco, Cal. and 
 S. J. Lynch, 
 
 Santa Cruz, Cal. 
 
 Improvement in protecting wooden 
 piles. 
 
 215,600 
 
 May 20, 1879 
 
 Louis Cathman, 
 Washington, D. C. 
 
 Drying apparatus. 
 
 766,340 
 
 Aug. 2, 1904 
 
 Jas. H. Catling, 
 Murfreesborough, N. C. 
 
 Improvement in treating the timber 
 of old field pines. 
 
 113,158 
 
 Mar. 28, 1871 
 
APPENDICES 
 List of U. S. Patents on Wood Preservation. — Continued 
 
 283 
 
 Name and address of 
 inventor 
 
 Title of patent 
 
 No. of 
 patent 
 
 Date issued 
 
 J. W. Geibel, 
 Loysburg, Pa. 
 
 Process of removing sap, etc., from 
 wood. 
 
 825,819 
 
 July 10, 1906 
 
 Joseph F. Geisler, 
 New York, N. Y. 
 
 Fireproofing and preserving wood. 
 
 660,614 
 
 May 19, 1896 
 
 Jos. F. Geisler, 
 New York, N. Y. 
 
 Process of fireproofing and preserv- 
 ing wood. 
 
 675,826 
 
 June 4, 1901 
 
 Jos. F. Geisler, 
 New York, N. Y. 
 
 Process of fireproofing wood. 
 
 679,739 
 
 Aug. 6, 1901 
 
 J. S. George, 
 Newport, Cre. 
 
 Method of preserving timber. 
 
 533,587 
 
 Feb. 5, 1895 
 
 P. H. Gerhard, 
 Austin, Tex. 
 
 Apparatus for treating timber. 
 
 794,605 
 
 July 11, 1905 
 
 John Knowles and 
 Robert Gilbert, 
 London, Eng. 
 
 Method of preserving timber and 
 other vegetable products. 
 
 391 
 
 Sept. 21, 1837 
 
 C. C. & G. B. Gilman, 
 Eldora, Iowa. 
 
 Fireproofing building materials. 
 
 560,580 
 
 May 19, 1896 
 
 J. T. Gilmer, 
 Pensacola, Fla. 
 
 Sap and gum extractor. 
 
 858,380 
 
 July 2, 1907 
 
 J. L. Gilmore, 
 Minneapolis, Minn. 
 
 Apparatus for creosoting the ends 
 of poles. 
 
 797,275 
 
 Aug. 15, 1905 
 
 Edw. Gold, 
 Vancouver, Can. 
 
 Method of protecting piles. 
 
 686,282 
 
 Nov. 12, 1901 
 
 A. J. Goodwin, 
 New Smyrna, Fla. 
 
 Impregnating wood, etc., with 
 copper. 
 
 414,111 
 
 Oct. 29, 1889 
 
 Geo. Wm. Gordon, 
 Philadelphia, Pa. 
 
 Process of preserving wood. 
 
 751,981 
 
 Feb. 9, 1904 
 
 Aug. Gotthilf, 
 New York, N. Y. 
 
 Improvement in the method of pro- 
 tecting timber from destruction by 
 worms, dry rot or other processes 
 of spontaneous decay. 
 
 232 
 
 June 14, 1837 
 
 Wm. D. Grimahaw, 
 New York, N. Y. 
 
 Improvement in processes and ap- 
 paratus for preserving and curing 
 wood. 
 
 218,624 
 
 Aug. 19, 1879 
 
 Gustaf Grondal, 
 Djursholm, Sweden. 
 
 Channel-furnace for treating wood. 
 
 245,162 
 
 Oct. 31, 19Q5 
 
 Hugo Gronwald, 
 Berlin, Germany. 
 
 Process of preserving cork. 
 
 273,645 
 
 Sept. 11,"1906 
 
284 THE PRESERVATION OF STRUCTURAL TIMBER 
 List of U. S. Patents on Wood Preservation. — Continued 
 
 Name and address of „.., , 
 
 Title of patent 
 inventor 
 
 No. of 
 patent 
 
 Date issued 
 
 Hugo Gronwald, 
 Berlin, Germany. 
 
 Process of preserving cork. 
 
 830,831 
 
 Sept. 11, 1906 
 
 Tomaso Guisaani, 
 Milan, Italy. 
 
 Process of preserving wood. 
 
 707,224 
 
 Aug. 19, 1902 
 
 Tomaso Guissani, 
 Milan, Italy. 
 
 Apparatus for impregnating wood. 
 
 713,630 
 
 Nov. 13, 1902 
 
 Stuart Gwynn, 
 New York, N. Y. 
 
 Improved process of saturating 
 wood, cloth, paper, etc., with 
 paraffine. 
 
 52,788 
 
 Feb. 20, 1866 
 
 Erwin Hagen, 
 St. Louis, Mo. 
 
 Preserving wood. 
 
 246,762 
 
 Sept. 6, 1881 
 
 Francis Hall, 
 Tacoma, Wash. 
 
 Method of preserving wood. 
 
 806,493 
 
 Cot. 10, 1893 
 
 Wm. A. Hall, 
 New York, N. Y. 
 
 Art of coloring and fireproofing 
 wood. 
 
 961,123 
 
 June 14, 1910 
 
 Alex, Hamar, 
 Hungary, Austria. 
 
 Improvement in preserving wood 
 from decay. 
 
 48,636 
 
 July 4, 1865 
 
 Alex, Hamar, 
 Hungary, Austria. 
 
 Improvement in preserving timber. 
 
 51,628 
 
 Deo. 12, 1865 
 
 Louis Hanson, 
 Wilmington, N. C. 
 
 Apparatus for preserving and creo- 
 soting wood. 
 
 722,505 
 
 Mar. 10, 1903 
 
 Ludvig Hansen and 
 Andrew Smith, 
 Wilmington, N. C. 
 
 Apparatus for creosoting wood. 
 
 316,961 
 
 May 5, 1885 
 
 Ludvig Hansen and 
 Andrew Smith, 
 Wilmington, N. C. 
 
 Process for preserving wood. 
 
 317,129 
 
 May 5, 1885 
 
 Ludvig Hansen and 
 Andrew Smith, 
 Wilmington, N. C. 
 
 Wood-preserving apparatus. 
 
 322,819 
 
 July 21, 1885 
 
 Thos. Hanvey, 
 Lancaster, N. Y. 
 
 Improvement in preparing and 
 preserving wood. 
 
 62,956 
 
 Mar. 19, 1867 
 
 Smith T. Harding, 
 Morrison, 111. 
 
 Improved compound for preserv- 
 ing wood. 
 
 68,069 
 
 Aug. 27, 1867 
 
 Louis Harmyer, 
 Cincinnati, Ohio. 
 
 Improved composition for preserv- 
 ing wood, metal, canvas, etc. 
 
 73,246 
 
 Jan. 14, 1868 
 
 S. E. Haskin, 
 Avooa, N. Y. 
 
 Method of vulcanizing wood. 
 
 399,196 
 
 Mar. 5, 1889 
 
APPENDICES 285 
 
 List of U. S. Patents on Wood Preservation. — Continued 
 
 Name and address of 
 inventor 
 
 Title of patent 
 
 No. of 
 patent 
 
 Date issued 
 
 S. E. Haskin, 
 Avooa, N. Y. 
 
 Process of and apparatus for vul- 
 canizing wood. 
 
 488,967 
 
 Deo. 27, 1892 
 
 Fritz Hasselmann, 
 Rapfelburg, Germany. 
 
 Method of impregnating wood. 
 
 580,488 
 
 April 13, 1897 
 
 Fritz Hasselmann, 
 Munich-Nymphenburg, 
 Ger. 
 
 Method of impregnating wood. 
 
 626,538 
 
 June 6, 1899 
 
 Hermann Haupt, 
 Philadelphia, Pa. 
 
 Improvement in drying, preserving, 
 and coloring wood or other fibrous 
 material. 
 
 99,186 
 
 Jan. 25, 1870 
 
 Robt. T. Havens, 
 Wilmington, thio. 
 
 Improved process for preparing 
 wood for boots and shoes. 
 
 54,339 
 
 May 1, 1866 
 
 Joshua R. Hayes, 
 Washington, D. C. 
 
 Improvement in preserving wood. 
 
 107,904 
 
 Oct. 4, 1870 
 
 Ira Hayford, 
 Boston, Mass. 
 
 Improvement in the process and 
 apparatus for treating wood. 
 
 101,012 
 
 Mar. 22, 1870 
 
 Ira Hayford, 
 Boston, Mass. 
 
 Improvement in processes and ap- 
 paratus for treating wood. 
 
 127,482 
 
 June 4, 1872 
 
 Ira Hayford, 
 Boston, Mass. 
 
 Improvement in apparatus and 
 processes for preserving wood. 
 
 194,773 
 
 Sept. 4, 1877 
 
 Wm. Hayman, 
 Taunton, Mass. 
 
 Improvement in compositions for 
 preserving wood. 
 
 110,652 
 
 Jan. 3, 1871 
 
 Theo. Wm. Heinemann, 
 New York, N. Y. 
 
 Improved mode of purifying^ sea- 
 soning, and preserving wood. 
 
 76,767 
 
 Apr. 14, 1868 
 
 Theo. Wm. Heinemann, 
 New York, N. Y. 
 
 Improved method of seasoning and 
 preserving wood. 
 
 94,204 
 
 Aug. 17, 1869 
 
 T. W. Heinemann, 
 New York, N. Y. 
 
 Improved process and apparatus 
 for preserving wood. 
 
 95,474 
 
 Oct. 5, 1869 
 
 Hubert, Higgins, 
 Cambridge, Eng. 
 
 Apparatus for impregnating and 
 seasoning wood. 
 
 695,152 
 
 Mar. 11, 1902 
 
 Arthur Holmes, 
 Cortland, N. Y. 
 
 Improvement in preserving wood 
 from decay. 
 
 62,334 
 
 Feb. 26, 1876 
 
 Ira Holmes, 
 Moscow, N. Y. 
 
 Improvement in compounds for 
 preserving wood. 
 
 124,358 
 
 Mar. 5, 1872 
 
 H. L. Houghton, 
 Morrison, 111. 
 
 Improved composition for harden- 
 ing and preserving wood. 
 
 65,674 
 
 June 11, 1867 
 
 Chas. Howard, 
 New York, N. Y. 
 
 Process of and apparatus for satu- 
 rating wood. 
 
 657,271 
 
 Mar. 31, 1896 
 
286 THE PRESERVATION OF STRUCTURAL TIMBER 
 List of U. S. Patents on Wood Preservation. — Continued 
 
 Name and address of 
 inventor 
 
 Title of patent 
 
 No. of 
 patent 
 
 Date issued 
 
 Chas. Howard, 
 New York, N. Y. 
 
 Process for preserving wood. 
 
 899,400 
 
 Sept. 22, 1908 
 
 Wm. Howe, 
 Seattle, Wash. 
 
 Pile-protector. 
 
 900,929 
 
 Oct. 13, 1908 
 
 Frank A. Howig, 
 San Francisco, Cal. 
 
 Improvement in production of 
 wooden bottle-stoppers and bungs. 
 
 197,220 
 
 Nov. 20, 1877 
 
 Pierre Hugon, 
 Paris, France. 
 
 Improvement in apparatus for car- 
 bonizing wood. 
 
 48,882 
 
 July 18, 1865 
 
 D. W. Hunt, 
 San Francisco,Cal. 
 
 Improved machine for kyanizing 
 wood. 
 
 91,848 
 
 June 22, 1869 
 
 David W. Hunt, 
 San Francisco, Cal. 
 
 Improvement in machines for kyan- 
 izing wood. 
 
 6,848 
 
 Jan. 11, 1876 
 
 John Huntington, 
 Cleveland, Ohio. 
 
 Improvement in devices for impreg- 
 nating timber with antiseptic fluid. 
 
 171,135 
 
 Deo. 14, 1875 
 
 John Huntington, 
 Cleveland, Ohio. 
 
 Improvement in devices for impreg- 
 nating timber with antiseptic 
 fluids. 
 
 171,136 
 
 Dec. 14, 1875 
 
 Warren Iddings, 
 Warren Ohio. 
 
 Preserving and hardening wood. 
 
 398,619 
 
 Feb. 26, 18&9 
 
 B. A. Jeager, 
 Bower's Station, Pa. 
 
 Improved compound for preserving 
 wood. 
 
 81,172 
 
 Aug. 18, 1868 
 
 Paul Jaeger, 
 Esslingen, Germany. 
 
 Method of and apparatus for im- 
 pregnating and dyeing wood. 
 
 578,516 
 
 Mar. 9, 1897 
 
 B. H. Jenks, 
 Bridesburg, Pa. 
 
 Improved process for coloring wood. 
 
 55,110 
 
 May 29, 1866 
 
 B, H. Jenks, 
 Bridesburg, Pa. 
 
 Improved mode of treating wood 
 for the manufacture of carding- 
 eugines. 
 
 55,111 
 
 May 29, 1866 
 
 B. H. Jenks, 
 Bridesburg, Pa. 
 
 Improved process of seasoning 
 wood. 
 
 58,425 
 
 Oct. 2, 1866 
 
 Joseph Jones, 
 New Orleans, La. 
 
 Improvement in preserving wood. 
 
 118,245 
 
 Aug. 18, 1871 
 
 Thoa. Jones, 
 Calstock, Eng. 
 
 Improvement in processes for pre- 
 serving wood. 
 
 155,191 
 
 Sept. 22, 1874 
 
 'Wm. H. Jones, 
 Rochester, N. Y. 
 
 Improvement in processes of pre- 
 serving wood. 
 
 132,584 
 
 Oct. 29, 1872 
 
APPENDICES 
 List of U. S. Patents on Wood Preservation. — Continued 
 
 287 
 
 Name^and address of 
 inventor 
 
 Title of patent 
 
 No. of 
 patent 
 
 Date issued 
 
 Chas. Karmrodt and 
 Nicholas Tiiilmany, 
 Bonn, Prussia. 
 
 Improvement in preserving wood. 
 
 132,584 
 
 Mar. 30, 1869 
 
 Carl Kleinsclimidt, 
 Seattle, Wash. 
 
 Wood-preserving compound. 
 
 697,632 
 
 Apr. 15, 1902 
 
 Ernst Koepfer, 
 Vienna, Austria-Hungary. 
 
 Apparatus for impregnating wood. 
 
 910,546 
 
 Jan.' 26, 1909 
 
 Franz L. Konrad, 
 Munster, Germany. 
 
 Method of fireproofing wood. 
 
 '629,861 
 
 Aug.'l, 1899 ' 
 
 H. E. Kreuter, 
 Dallas, Tex. 
 
 Apparatus for treating timber, rail- 
 way ties, etc. 
 
 249,953 
 
 Nov. 22, 1881 
 
 Rudolph KroU, 
 Spearfish, So. Dak. 
 
 Wood preservation by means of 
 borings in timber to permit the 
 entrance of air. 
 
 727,975 
 
 May 12, 1903 
 
 George Kron, 
 Copenhagen, Denmark. 
 
 Method of producing liquid-tight 
 joints for impregnating wood. 
 
 256,456 
 
 April 19, 1905 
 
 Berthold Kuokuck, 
 Wannsee near Berlin, Ger. 
 
 Apparatus for impregnating wood 
 or other substances. 
 
 866,487 
 
 Sept. 17, 1907 
 
 John Howard Kyan, 
 Cheltenham, Eng. 
 
 Improved mode of preserving tim- 
 ber and other vegetable sub- 
 stances from decay. 
 
 800 
 
 June 23, 1838 
 
 Sylvester W. Labrot, 
 New Orleans, La. 
 
 Process of preserving wood. 
 
 862,488 
 
 Aug. 6, 1907 
 
 Jas. Guy La Fonte, 
 Indianapolis, Ind. 
 
 Improvement in treatment of wood 
 for corset stays, etc. 
 
 201,022 
 
 Mar. 5, 1878 
 
 Fred. E. Lampert, 
 San Francisco, Cal. 
 
 Coating for piles. 
 
 454,744 
 
 June 23, 1891 
 
 C. S. Lawrence, 
 Plainfield, Wis. 
 
 Wood-preserving compound. 
 
 682,363 
 
 Sept. 10, 1901 
 
 Fred. Lear, 
 St. Louis, Mo. 
 
 Improvement in coloring and pre- 
 serving wood. 
 
 109,027 
 
 Nov. 8, 1870 
 
 Fred. Lear, 
 St. Louis, Mo. 
 
 Improvement in preserving, color- 
 ing, and seasoning wooil 
 
 116,969 
 
 July 11, 1871 
 
 Georg Friedrich Lebioda, 
 Boulogne-sur-Seine, 
 France. 
 
 Apparatus for dyeing and impreg- 
 nating wood. 
 
 609,442 
 
 Aug. 23, 1898 
 
 Georg Friedrich Lebioda, 
 Boulogne-sur-Seine, 
 France. 
 
 Apparatus for impregnating wood. 
 
 644,252 
 
 Feb. 27, 1900 
 
288 THE PRESERVATION OF STRUCTURAL TIMBER 
 List of U. S. Patents on Wood Preservation. — Continued 
 
 Name and address of 
 inventor 
 
 Title of patent 
 
 No. of 
 patent 
 
 Date issued 
 
 Georg Friedrioh Lebioda, 
 Boulogne-sur-Seine, 
 France. 
 
 Apparatus for impregnating wood. 
 
 655,788 
 
 Aug. 14, 1900 
 
 Georg Friedrioh Lebioda, 
 Boulogne-sur-Seine, 
 France. 
 
 Apparatus for impregnating wood. 
 
 689,317 
 
 Deo. 17, 1901 
 
 Georg Friedrich Lebioda, 
 Boulogne-sur-Seine, 
 France. 
 
 Process of obtaining impregnated 
 wood. 
 
 729,362 
 
 May 26, 1903 
 
 Clias. T. Lee, 
 Boston, Mass. 
 
 Process of preserving wood. 
 
 419,858 
 
 Jan. 21, 1890 
 
 Louis L. Le Franc, 
 Bosc-le-Hard, France. 
 
 Manufacture of wooden stoppers. 
 
 663,234 
 
 Deo. 4, 1900 
 
 lens P. Lihme, 
 Cleveland, Ohio. 
 
 Preserved wood and process of pre- 
 paring same. 
 
 756,173 
 
 Mar. 29, 1904 
 
 John T. Lloyd, 
 New York, N. Y. 
 
 Vulcanizing wood. 
 
 566,591 
 
 Aug. 25, 1896 
 
 Fred. A. Lobert, 
 National City, Gal. 
 
 Compound for preserving timber. 
 
 546,960 
 
 Sept. 24, 1895 
 
 Rembrandt Lockwood, 
 Brooklyn, N. Y. 
 
 Improvement in processes of treat- 
 ing wood. 
 
 174,914 
 
 Mar. 21, 1876 
 
 John Thos. Logan, 
 Texarkana, Tex. 
 
 Process of preserving wood. 
 
 831,793 
 
 Sept. 25, 1906 
 
 J. T. Logan, 
 Texarkana, Tex. 
 
 Apparatus for treating the butt- 
 ends of logs. 
 
 836,592 
 
 Nov. 20, 1906 
 
 John Loomis, 
 JefFersonville, Ind. 
 
 Solution for seasoning and pre- 
 serving wood. 
 
 273,861 
 
 Mar. 13, 1883 
 
 Ira Loughborough, 
 Pittsford, N. Y. 
 
 Apparatus for saturating railroad 
 ties. 
 
 533,543 
 
 Feb. 5, 1895 
 
 Cuthbert B. Lowry, 
 Lexington, Ky. 
 
 Wood impregnation. 
 
 831,450 
 
 Sept. 18, 1906 
 
 Cuthbert B. Lowry,. 
 
 Lexington, Ky., 
 Richard Bernhard, 
 
 Chicago, 111. 
 
 Means for withdrawing and con- 
 densing vapors. 
 
 902,097 
 
 Oct. 27, 1908 
 
 M. A. Luckenbach, 
 Denver, Col. 
 
 Process of treating wood to prevent 
 decay. 
 
 473,705 
 
 Apr. 26, 1892 
 
 Geo. A. Ludington 
 Akron, Ohio. 
 
 Method of vulcanizing tires in con- 
 tinuous lengths. 
 
 754,078 
 
 Mar. 8, 1904 
 
APPENDICES 
 List of U. S. Patents on Wood Preservation. — Continued 
 
 289 
 
 Name and address of 
 inventor 
 
 Title of patent 
 
 No. of 
 patent 
 
 Date issued 
 
 Gregory Lukina, 
 Sweetwater, 111. 
 
 Preserving wood. 
 
 245,845 
 
 Aug. 16, 1881 
 
 Antionette Macauley, 
 Ft. Dodge, Iowa. 
 
 Wood-preserving compound. 
 
 778,321 
 
 Dec. 27, 1904 
 
 J. C. Mallonee, 
 Charleston, S. C. 
 
 Process of preserving wood. 
 
 386,999 
 
 July 31, 1888 
 
 Ernst Marmetsohke, 
 Sohopfurth near 
 Eberawalde, Ger. 
 
 Method of impregnating timber 
 and the like. 
 
 898,246 
 
 Sept. 8, 1908 
 
 J. C. Marshall, 
 Oakland, Cal. 
 
 Wood-preserving compound. 
 
 259,030 
 
 June 6, 1882 
 
 J. A. Mathieu, 
 Detroit, Mich. 
 
 Apparatus for preserving railway 
 ties. 
 
 332,097 
 
 Dec. 8, 1885 
 
 H. G. MoGonegal. 
 Washington, D. C. 
 
 Improvement in apparattus for pre- 
 serving wood. 
 
 140,520 
 
 July 1, 1873 
 
 Jas. McKeon, 
 Oakland, Cal. 
 
 Process of preserving timber. 
 
 461,365 
 
 Oct. 13, 1891 
 
 John McLaohlan, 
 Chicago, 111. 
 
 Process of solidifying wood. 
 
 575,973 
 
 Jan. 26, 1897 
 
 A. R. MoNair, 
 New York, N. Y. 
 
 Improvement in preserving wood 
 from decay and mildew. 
 
 94,626 
 
 Sept. 7, 1869 
 
 Wm. K. Miller, 
 Canton, Ohio. 
 
 Improvement in burial cases. 
 
 57,545 
 
 Aug. 28, 1866 
 
 E. P. Morong, 
 Boston, Mass. 
 
 Improvement in preserving wooden 
 pavements. 
 
 134,479 
 
 Deo. 31, 1872 
 
 L. D. Mott, 
 Marshalltown, la. 
 
 Compound for preserving wood and 
 metal. 
 
 251,918 
 
 Jan. 3, 1882 
 
 H. G. Muller, 
 San Francisco, Cal. 
 
 Preserved wood. 
 
 236,065 
 
 Dec. 28, 1880 
 
 Peter Murray, 
 Seattle, Wash. 
 
 Method of preserving timber. 
 
 495,991 
 
 Apr. 25, 1893 
 
 H. C. Myers, 
 Cleveland, Ohio. 
 
 Method of vulcanizing wood. 
 
 537,393 
 
 Apr. 9, 1895 
 
 Robt. Newell, 
 Philadelphia, Pa. 
 
 Improvement in compounds for 
 coating wood and other articles to 
 render them acid proof. 
 
 140,530 
 
 June 21, 1873' ' 
 
 B. R. Nickerson, 
 San Francisco, Cal. 
 
 Improvement in preserving and 
 hardening wood. 
 
 107,620 
 
 Sept. 20, 1870 
 
 19 
 
290 THE PRESERVATION OF STRUCTURAL TIMBER 
 List of U. S. Patents on Wood Preservation. — Continued 
 
 Name and address of 
 inventor 
 
 Title of patent 
 
 No. of 
 patent 
 
 Date issued 
 
 Wm. C. Jones, 
 W. J. R. Stratford, 
 F. B. Byrnes, and 
 E. J. Nixon, 
 Texarkana, Tex. 
 
 Process of saturating wood. 
 
 216,286 
 
 Nov. 7, 1905 
 
 Patrick O'Brien, 
 South Bend, Ind. 
 
 Improvement in processes for pre- 
 paring the surface of wood- work of 
 carriages. 
 
 175,621 
 
 Apr. 4, 1876 
 
 John Oliver, 
 Toronto, Can. 
 
 Improvement in preserving and 
 drying lumljer. 
 
 142,347 
 
 Sept. 2, 1873 
 
 Geo. Palmer 
 Littlestown, Pa. 
 
 Improvement in preserving wood. 
 
 49,146 
 
 Aug. 1, 1865 
 
 Chas. W. Parker, 
 Genesee Fork, Pa. 
 
 Preserving posts, etc. 
 
 378,459 
 
 Feb. 28, 1888 
 
 Wm. D. Patten, 
 New York, N. Y. 
 
 Fireproofing compound. 
 
 802,311 
 
 Oct. 17, 1905 
 
 Jos. Paul, and 
 Ira Hayford, 
 Boston, Mass. 
 
 Improved process of treating wood 
 to preserve, season and give it a 
 better surface. 
 
 95,583 
 
 Oct. 5, 1869 
 
 Chas. Payne, 
 South Lambeth, Eng. 
 
 Improvement in processes for pre- 
 serving wood. 
 
 7,399 
 
 May 28, 1850 
 
 Wm. T. Pelton, 
 New York, N. Y. 
 
 Improvement in portable appa- 
 ratus for preserving wood. 
 
 113,338 
 
 Apr. 4, 1871 
 
 Wm. T. Pelton, 
 New York, N. Y. 
 
 Improvement in apparatus for 
 seasoning and preserving wood. 
 
 124,080 
 
 Feb. 27, 1872 
 
 Herbert Elmer Percival, 
 Houston, Tex. 
 
 Wood-preserving compound. 
 
 891,726 
 
 June 23, 1908 
 
 Saml. R. Percy, 
 New York, N. Y. 
 
 Preserving wood. 
 
 249,856 
 
 Nov. 22, 1881 
 
 Josef Pfister, 
 Vienna, Austria-Hungary. 
 
 Method of preserving timber. 
 
 683,792 
 
 Oct. 1, 1901 
 
 Josef Pfister, 
 Vienna, Austria-Hungary-. 
 
 Process of staining woods. 
 
 708,069 
 
 Sept. 2, 1903 
 
 Josef Pfister, 
 Vienna, Austria-Hungary. 
 
 Apparatus for impregnating or 
 staining wood. 
 
 735,019 
 
 July 28, 1903 
 
 Geo. Phillips, 
 Key West, Fla. 
 
 Coating for wooden structures. 
 
 414,247 
 
 Nov. 5, 1889 
 
 Geo. Phillips, 
 Key West, Fla. 
 
 Process of preserving wood. 
 
 414,249 
 
 Nov. 5, 1889 
 
APPENDICES 
 List of U. S. Patents on Wood Preservation. — Continued 
 
 291 
 
 Name and address of 
 inventor 
 
 Title of patent 
 
 No. of 
 patent 
 
 Date issued 
 
 A. M. Pierce, 
 Brooklyn, N. Y. 
 
 Process of fireproofing wood. 
 
 737,468 
 
 Aug. 25, 1903 
 
 Wm. Powell, 
 Liverpool, Eng, 
 
 Vulcanized wood and process of 
 vulcanizing same. 
 
 755,240 
 
 Mar. 22, 1904 
 
 Theo. Pridham, 
 Petersham, 
 New So. Wales. 
 
 Coating for timber. 
 
 453,821 
 
 June 9, 1891 
 
 D. R. Prindle, 
 East Bethany, N. Y. 
 
 Improved process of preserving 
 wood and timber. 
 
 63,300 
 
 Mar. 26, 1867 
 
 Thos. N. Prudden, 
 San Francisco, Cal. 
 
 Method and apparatus for protect- 
 ing marine wooden structures. 
 
 855,588 
 
 June 4, 1907 
 
 A. D. Purinton, 
 Dover, N. H. 
 
 Improved composition for setting 
 posts, timbers, etc. 
 
 78,691 
 
 June 9, 1868 
 
 Geo. Pustkuchen, 
 Hoboken, N. J. 
 
 Improved apparatus for impreg- 
 nating wood with tar and other 
 materials. 
 
 64,703 
 
 May 14, 1867 
 
 Jos. W. Putman, 
 New Crleans, La. 
 
 Apparatus for treating wood for 
 preserving it. 
 
 247,947 
 
 Oct. 4, 1881 
 
 Jos. W. Putman, 
 New Orleans, La. 
 
 Apparatus tor treating timber with 
 antiseptics. 
 
 266,516 
 
 Oct. 24, 1882 
 
 Jos. W. Putman, 
 New Crleans, La. 
 
 Compound for preserving timber. 
 
 404,302 
 
 May 28, 1889 
 
 Jos. W. Putman, 
 New Crleans, La. 
 
 Wood-preserving compound. 
 
 406,907 
 
 June 25, 1889 
 
 Randolph. F. Eadebaugh, 
 Tacoma, Wash. 
 
 Process of and apparatus for treat- 
 ing wooden stopples. 
 
 535,770 
 
 Mar. 12, 1895 
 
 Frederick Ransome, 
 Ipswich, Great Britain. 
 
 Improvement in preserving timber. 
 
 65,216 
 
 May 29, 1866 
 
 John M. Reid, 
 Allegheny City, Pa. 
 
 Improvement in preserving wood. 
 
 154,767 
 
 Sept. 8, 1874 
 
 Peter C. Reilly, 
 Indianapolis, Ind. 
 
 Preserved wood and method of 
 making same. 
 
 901,557 
 
 Oct. 20, 1908 
 
 Peter C. Reilly, 
 Indianapolis, Ind. 
 
 Preserved wood. 
 
 899,904 
 899,905 
 
 Sept. 29, 1908 
 
 R. P. Reynolds, 
 Walla Walla, Wash. 
 
 Timber preservative. 
 
 792,458 
 
 July 13, 1905 
 
 H. L. Ricks, 
 Eureka, Cal. 
 
 Method of preserving Bubmeged 
 timbers. 
 
 380,820 
 
 Apr. 10, 1888 
 
292 THE PRESERVATION OF STRUCTURAL TIMBER 
 List of TJ. S. Patents on Wood Preservation. — Continued 
 
 Name and address of 
 inventor 
 
 Title of patent 
 
 No. of 
 patent 
 
 Date igsued 
 
 Saml. Ringgold, Fla. and 
 Edw. Earle, 
 Savannah, Ga. 
 
 Improved mode of preserving tim- 
 ber by boiling the same in lime- 
 water. 
 
 877 
 
 Aug. 6, 1838 
 
 L. S. Robbins, 
 New York, N. Y. 
 
 Improved process for preserving 
 wood. 
 
 47,132 
 
 Apr. 4, 1865 
 
 L. S. Robbing, 
 New York, N. Y. 
 
 Improved mode of preserving 
 telegraph poles. 
 
 89,345 
 
 Apr. 27, 1869 
 
 L. S. Robbing, 
 New York, N. Y. 
 
 Improvement in processes for pre- 
 serving wood. 
 
 165,768 
 
 July 20, 1875 
 
 L. S. Robbing, 
 Elizabeth, N. J. 
 
 Improvement in processes and ap- 
 paratus for preserving wood or 
 lumber. 
 
 217,022 
 
 July 1, 1879 
 
 L. S. Robbing, 
 New York, N. Y. 
 
 Preserving wood. 
 
 9,512 
 
 Deo. 21, 1880 
 
 J. G. Robingon, 
 Brooklyn, Ala. 
 
 Fence-post. 
 
 655,638 
 
 Aug. 7, 1900 
 
 W. W. Robinson, 
 Ripon, Wig. 
 
 Process of preserving wood. 
 
 294,676 
 
 Mar. 4, 1884 
 
 H. N. Roge, 
 Edouard Poret, 
 Pierre Baffoy, and 
 Pierre Dupre, 
 Paris, France. 
 
 Improvement in processes of pre- 
 serving wood and other vegetable 
 matters. 
 
 191,257 
 
 May 29, 1877 
 
 Jas. Rowe, 
 San Francisco, Cal. 
 
 Composition for protecting piles. 
 
 440,832 
 
 Nov. 18, 1890 
 
 Sam'l. M. Rowe, 
 Chicago, 111. 
 
 Door mechanism for creosoting 
 tankg. 
 
 908,144 
 
 Dec. 29, 1908 
 
 Karl Rucker, 
 Zernsdorf, Ger. 
 
 Method of fireproofing wood. 
 
 691,812 
 
 Jan. 28, 1902 
 
 Max Ruping, 
 Charlottenburg, Ger. 
 
 Method of impregnating wood. 
 
 707,799 
 709,799 
 
 Sept. 23, 1902 
 
 Julius Rutgers, 
 Berlin, Germany. 
 
 Wood-impregnating compound and 
 method of making game. 
 
 662,310 
 
 Nov. 20, 1900 
 
 Emile Sabathe, and 
 Louis Jourdan, 
 Paris, France. 
 
 Improvement in impregnating 
 substances with preservative 
 material. 
 
 58,036 
 
 Sept. 11, 1866 
 
 Thos. H. Sampson 
 New Orleans, La. 
 
 Process of preserving lumber. 
 
 403,144 
 
 May 14, 1889 
 
APPENDICES 
 List of U. S. Patents on Wood Preservation. — Continued 
 
 293 
 
 Name and address of 
 inventor 
 
 Title of patent 
 
 No. of 
 patent 
 
 Date issued 
 
 J. L. Samuela, 
 San Francisco, Cal. 
 
 Improved composition for prepar- 
 ing and hardening wood and pre- 
 serving the same. 
 
 60,794 
 
 Jan. 1, 1867 
 
 Chr. Schallberger, 
 Seattle, Wash. 
 
 Compound for protecting timber. 
 
 678,201 
 
 July 9, 1901 
 
 Chr. Schallberger, 
 Vancouver, Can. 
 
 Wood-preserving compound. 
 
 714,521 
 
 Nov. 25, 1902 
 
 Julius Schenkel, 
 Dortmund, Ger. 
 
 Process of impregnating wood. 
 
 655,459 
 
 Aug. 7, 1900 
 
 Julius Schenkel, 
 Dortmund, Ger. 
 
 Process of fireproofing wood. 
 
 647,428 
 
 Apr. 10, 1900 
 
 P. Schmidt, 
 
 Preserving wood. 
 
 4,560 
 
 June 6, 1846 
 
 Jos. Schnelble, 
 New York, N. Y. 
 
 Method of and apparatus for sat- 
 urating corks. 
 
 599,798 
 
 Mar. 1, 1898 
 
 Chas. A. Seely, 
 New York, N. Y. 
 
 Improved method of impregnating 
 wood with oleaginous and saline 
 matters. 
 
 69,260 
 
 •Sept. 24, 1867 
 
 Jos. A. Bewail, 
 Denver, Colo. 
 
 Process of preserving wood. 
 
 374,208 
 
 Dee. 6, 1887 
 
 A. J. Sheldon, 
 Buffalo, N. Y. 
 
 Improvement in preserving wood. 
 
 106,625 
 
 Aug. 23, 1870 
 
 Morris Sherman, 
 Chattanooga, Tenn. 
 
 Means for securing heads to boilers, 
 cylinders, etc. 
 
 781,371 
 
 Jan. 31, 1905 
 
 S. L. Shuffleton, 
 Seattle, Wash. 
 
 Method of protecting wooden piles. 
 
 676,704 
 
 June 18, 1901 
 
 J. E. Siebel, 
 Chicago, 111. 
 
 Improvement in depilating hides 
 and preserving wood. 
 
 116,638 
 
 July 4, 1871 
 
 H. V. Simpson, 
 London, Eng. 
 
 Fireproofing wood. 
 
 646,101 
 
 Mar. 27, 1900 
 
 H. Y. Simpson, 
 London, Eng. 
 
 Process of fireproofing wood. 
 
 668,227 
 
 Feb. 19, 1901 
 
 Archibald J. Sinclair, 
 Chicago, 111. 
 
 Process of coating porous material 
 with asphalt. 
 
 893,391 
 
 July 14, 1908 
 
 Smith A. Skinner, 
 Hoosiok Falls, N. Y. 
 
 Cordage and twine to be used in 
 binding sheaves of grain. 
 
 255,040 
 
 Mar. 14, 1882 
 
 Bat Smith 
 Spanish Camp, Tex. 
 
 Composition for preserving wood. 
 
 244,327 
 
 July 12, 1881 
 
294 THE PRESERVATION OF STRUCTURAL TIMBER 
 List of U. S. Patents on Wood Preservation. — Continued 
 
 Name and address of m-.i ,^ ^ ^ 
 
 Title of patent 
 inventor 
 
 No. of 
 patent 
 
 Date Issued 
 
 Geo. B. Smith, 
 Philadelphia, Pa 
 
 Improvement in apparatus for pre- 
 serving wood. 
 
 160,846 
 
 Mar. 16, 1875 
 
 Geo. B. Smith, 
 Philadelphia, Pa. 
 
 Improvement in wooden shingles 
 made fire-proof. 
 
 199,001 
 
 Jan. 8, 1878 
 
 W. B. Smith, 
 La Fayette, 111. 
 
 Improved apparatus for saturating 
 timber. 
 
 62,295 
 
 Feb. 19, 1867 
 
 W. H. Smith, 
 Steubenville, Ohio. 
 
 Improvement in apparatus for in- 
 jecting preservative liquids into 
 wood. 
 
 111,784 
 
 Feb. 14, 1871 
 
 W. L. Smith, 
 New York, N. Y. 
 
 Apparatus for impregnating wood. 
 
 711,080 
 
 Cct. 14, 1902 
 
 P. S. Smout, 
 Everett, Wash. 
 
 Composition for preserving piles 
 and timber. 
 
 806,591 
 
 Deo. 5, 1905 
 
 Edw. Spaulding, 
 Brooklyn, N. Y. 
 
 Improved process for treating wood. 
 
 77,777 
 
 May 12, 1868 
 
 S. F. Spaulding, 
 Jerico, Conn. 
 
 Improvement in preparing veneers 
 for butter-boxes. 
 
 164,945 
 
 June 29, 1875 
 
 Geo. Speiz, 
 Dutch Kills, N. Y. 
 
 Preserving wood. 
 
 387,375 
 
 Aug. 7, 1888 
 
 Chas. F. Spicker, 
 New York, N. Y. 
 
 Improvement in coloring and hard- 
 ening wood. 
 
 3,635 
 
 June 24, 1844 
 
 I. B. Sprague, 
 Everett, Wash. 
 
 Process of preserving wood. 
 
 694,212 
 
 Feb. 25, 1902 
 
 Jas. D. Stanley, 
 Eastover, S. C. 
 
 Device for charring surface of 
 timber. 
 
 361,095 
 
 Apr. 12, 1887 
 
 Jas. D. Stanley, 
 Wilmington, N. C. 
 
 Apparatus for charring timber. 
 
 282,395 
 
 July 31, 1883 
 
 Jas. D. Stanley, 
 Eastover, S. C. 
 
 Device for charring logs. 
 
 361,193 
 
 Apr. 12, 1887 
 
 Chas. W. Stanton, 
 Mobile, Ala. 
 
 Apparatus for steaming wood. 
 
 735,608 
 
 Aug. 4, 1903 
 
 Adolphe Ste. Marie and 
 Alfred Hoffman, 
 Lyons, France. 
 
 Process of seasoning wood. 
 
 675,500 
 
 June 4, 1901 
 
 Jas. C. Stead, 
 Jersey City, N. J. 
 
 Improvement in apparatus for pre- 
 serving wood. 
 
 148,630 
 
 Mar. 17, 1874 
 
 L. M. Stern and Edw. M. 
 Kempner, Buffalo, N. Y. 
 
 Apparatus for impregnating wood. 
 
 662,104 
 
 Nov. 20, 1900 
 
APPENDICES 
 List of U. S. Patents on Wood Preservation. — Continued 
 
 295 
 
 Name and address of 
 inventor 
 
 Title of patent 
 
 No. of 
 patent 
 
 Date issued 
 
 F. A. Stevens, 
 Chicago, 111. 
 
 Improvement in apparatus for pre- 
 serving wood. 
 
 102,725 
 
 May 3, 1870 
 
 Chas. StoUberg, 
 Toledo, Ohio. 
 
 Sheet-metal sap receptacle or 
 vessel. 
 
 857,846 
 
 June 25, 1907 
 
 Richard Sutphen, 
 Freehold, N. J. 
 
 Improvement in wood-preserving 
 compositions. 
 
 120,009 
 
 Oct. 17, 1871 
 
 Geo. W. Swan, 
 San Francisco, Cal. 
 
 Improvement in the processes for 
 softening and toughening blocks of 
 wood. 
 
 142,298 
 
 Aug. 26, 1873 
 
 Wm. Taggart, 
 San Francisco, Cal. 
 
 Preserving piles. 
 
 261,045 
 
 July 18, 1882 
 
 A. H. Tait, 
 Jersey City, N. J. 
 
 Improvement in preserving wood. 
 
 115,784 
 
 June 6, 1871 
 
 Rudolf Tanczos, 
 Vienna, Austria-Hungary. 
 
 Fireproofing wood. 
 
 329,973 
 
 Nov. 10, 1885 
 
 Chas. Taylor, R. I. Murch- 
 iscn, and Geo. Sharpe, 
 Melbourne, Victoria. 
 
 Composition for preserving timber. 
 
 391,209 
 
 Oct. 16, 1888 
 
 J. H. Taylor, 
 New York, N. Y. 
 
 Improved process of preventing 
 decay in wood. 
 
 70,761 
 
 Nov. 12, 1867 
 
 Wm. B. Taylor, 
 Winterpark, Fla. 
 
 Composition for preserving wood. 
 
 759,938 
 
 May 17, 1904 
 
 L. N. Teachman, 
 Lincoln, Nebr, 
 
 Wood-preserving composition. 
 
 277,810 
 
 May 15, 1883 
 
 Horace Thayer, 
 Warsaw, N. Y. 
 
 Treating wood for the manufacture 
 of boxes, cases, etc. 
 
 45,537 
 
 Dec. 20, 1864 
 
 Waldemar Thilmany, 
 Cleveland, Ohio. 
 
 Improvement in apparatus for im- 
 pregnating timber with antiseptics. 
 
 177,770 
 
 May 23, 1876 
 
 Waldemar Thilmany, 
 Cleveland, Ohio. 
 
 Improvement in processes for pre- 
 serving timber. 
 
 202,678 
 
 Apr. 23, 1878 
 
 Nathan H. Thomas, 
 New Orleans, La. 
 
 Improvement in processes for pre- 
 serving wood. 
 
 113,706 
 
 Apr. 11, 1871 
 
 A. B. Tripler, 
 New Orleans, La. 
 
 Improvement in preserving wood. 
 
 104,916 
 
 June 28, 1870 
 
 A. B. Tripler, 
 New Orleans, La. 
 
 Improvement in preserving wood 
 for railroad ties, etc. 
 
 104,917 
 
 June 28, 1870 
 
 A. B. Tripler, 
 Philadelphia, Pa. 
 
 Improvementln processes for pre- 
 serving wooden pavements from 
 rot. 
 
 126,592 
 
 May 7, 1872 
 
296 THE PRESERVATION OF STRUCTURAL TIMBER 
 List of U. S. Patents on Wood Preservation. — Continued 
 
 Name and address of 
 inventor 
 
 Title of patent 
 
 No. of 
 patent 
 
 Date issued 
 
 A. B. Tripler, 
 New York, N. Y. 
 
 Improvement in processes for stain- 
 ing wood. 
 
 207,630 
 
 Sept. 3, 1878 
 
 A. B. Tripler, 
 New York.N. Y. 
 
 Improvement in the art of preserv- 
 ing wood. 
 
 208,649 
 
 Oct. 1, 1878 
 
 Abel D. Tyler, 
 Worcester, Mass. 
 
 Impregnating wood. 
 
 553,547 
 
 Jan. 28, 1896 
 
 Geo. S. Valentine, 
 Brooklyn, N. Y. 
 
 Process of and apparatus for pre- 
 serving wood by impregnation to 
 given heights. 
 
 285,087 
 
 Sept. 18, 1883 
 
 Rose L. Valleen, 
 Seattle, Wash. 
 
 Wood-preserving compound. 
 
 579,101 
 
 Mar. 16, 1897 
 
 G. A. Vivien and 
 Paul C. Vivien, 
 HonSeur, France. 
 
 Improvement in compositions for 
 preserving wood, coating ships' 
 bottoms, etc. 
 
 123,801 
 
 ? 
 
 J. G. Voorhees, 
 Aqueduct Mills, N. J. 
 
 Improvement in preserving wood. 
 
 121,141 
 
 Nov. 21, 1871 
 
 Martin Voorhees, Prince- 
 ton, andG. W. N. Custis, 
 Camden, N. J. 
 
 Improved process and apparatus for 
 seasoning and impregnating wood 
 with preservative material. 
 
 87,226 
 
 Feb. 23, 1869 
 
 John F. Walter, Jr., 
 Brooklyn, N. Y. 
 
 Process of drying and seasoning 
 lumber. 
 
 287,351 
 
 Oct. 23, 1883 
 
 Fred J. Warren, 
 Newton, Mass. 
 
 Wooden block pavement. 
 
 794,758 
 
 July 18, 1905 
 
 Chas. G. Waterbury, 
 New York, N. Y. 
 
 Improvement in processes for hard- 
 ening and preserving wood. 
 
 124,402 
 
 Mar. 5, 1872 
 
 Ezra Webb, 
 New York, N. Y. 
 
 Improvement in preserving wood. 
 
 108,659 
 
 Oct. 25, 1870 
 
 Peter Welch, 
 St. Louis, Mo. 
 
 Improvement in preserving wood. 
 
 129,503 
 
 July 16, 1872 
 
 Wm. Wellhouse, & Erwin 
 Hagen, St. Louis, Mo. 
 
 Improvement in preserving wood. 
 
 216,589 
 
 June 17, 1879 
 
 Pelag Werni, 
 Philadelphia, Pa. 
 
 Improvement in compounds for 
 preserving wood. 
 
 164,786 
 
 June 22, 1875 
 
 S. P. Wheeler, 
 Bridgeport, Conn. 
 
 Improvement in the manufacture of 
 articles of compressed wood. 
 
 101,552 
 
 Apr. 5, 1870 
 
 S. P. Wheeler, 
 Bridgeport, Conn. 
 
 Improved process of treating wood. 
 
 101,553 
 
 Apr. 5, 1870 
 
APPENDICES 297 
 
 List of U. S. Patents on Wood Preservation. — Continued 
 
 Name and address of 
 Inventor 
 
 Title of patent 
 
 No. of 
 patent 
 
 Date issued 
 
 Thos. B. White, 
 Warsaw, Mo. 
 
 Post-protector. 
 
 868,953 
 
 Oct. 22, 1907 
 
 Sidney S. Williams, 
 Providence, R. I. 
 
 Apparatus for use in treating wood. 
 
 904,589 
 
 Nov. 24, 1908 
 
 Sigmund Willner, 
 London, Eng. 
 
 Apparatus for impregnating wood. 
 
 620,627 
 
 Mar. 7, 1899 
 
 Sigmund Willner, 
 London, Eng. 
 
 Apparatus for impregnating wood. 
 
 676,060 
 
 June 11, 1901 
 
 Sigmund Willner, 
 New York, N. Y. 
 
 Apparatus for impregnating wood. 
 
 771,689 
 
 Oct. 4, 1904 
 
 Sigmund Willner, 
 Memphis, Tenn. 
 
 Apparatus for forcing fluids into 
 wood. 
 
 807,411 
 
 Deo. 12, 1905 
 
 Sigmund Willner, 
 Chicago, 111. 
 
 Apparatus for injecting chemicals 
 into logs. 
 
 896,785 
 
 Aug. 25, 1908 
 
 Jas. P. Witherow, 
 Pittsburg, Pa. 
 
 Process of and apparatus for vul- 
 canizing wood. 
 
 446,501 
 
 Feb. 17, 1891 
 
 Jas. P. Witherow, 
 Pittsburg, Pa. 
 
 Apparatus for vulcanizing wood. 
 
 446,500 
 
 Feb. 17, 1891 
 
 Jas. H. Young, 
 New, York, N. Y. 
 
 Apparatus for impregnating wood. 
 
 329,799 
 
 Nov. 3, 1885 
 
 Wm. Youngblood, 
 Jamaica, N. Y. 
 
 Method of preserving wood. 
 
 398,366 
 
 Feb. 19, 1889 
 
 METHOD OF ANALYZING ZINC CHLORIDEi 
 
 Sampling. — A fair average sample must be taken from one out 
 of every ten drums. Quickly transfer the sample to a clean, dry. 
 salt-mouthed bottle, stopper, hermetically seal and send to the 
 laboratory for test. The sample should be marked with a 
 number or other device, corresponding to the drum or lot from 
 which it was taken. 
 
 Insoluble Basic Zinc Chloride. — Pulverize about 10 grams of 
 the fused zinc chloride by crushing between filter papers, and 
 quickly transfer to a weighing bottle. This operation must be 
 performed quickly, owing to the deliquescent nature of the sub- 
 stance. Weigh the bottle plus the sample, transfer the sample to 
 500 c.c. of water in a beaker, and weigh the bottle again; the 
 
 ^ From the Proceedings of the American Wood Preservers' Association. 
 
 20 
 
298 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 weight of the sample is thus obtained by difference. Cover the 
 beaker and allow the solution to stand for 12 hours. 
 
 Filter through a weighed Gooch crucible into a liter flask. 
 Wash the residue with cold water until it is free from chlorides. 
 Dry the basic zinc chloride at 100° C. for about 12 hours and 
 weigh. 
 
 Dilute the filtrate to 1000 c.c. and mix thoroughly. 
 
 Ferric Chloride. — -Take 100 c.c. of the solution, boil, and pre- 
 cipitate the iron with ammonium hydroxide. Boil off the excess 
 of ammonia, filter and reject the filtrate. Dissolve the precipi- 
 tate off the paper with hot dilute hydrochloric acid, and reprecipi- 
 tate with ammonium hydroxide. Filter through the original 
 filter paper. Wash the ferric hydroxide 5 to 6 times with hot 
 water, ignite and weigh as Fe203. 
 
 Factor for metallic iron, 7, 
 
 Factor for ferric chloride, 1.0156. 
 
 Soluble ZincJ — Take 50 c.c. of the original solution, and add a 
 concentrated solution of sodium carbonate, until the solution is 
 slightly alkaline. Zinc is precipitated as basic carbonate. 
 Boil for 15 minutes. Decant through a weighed Gooch crucible 
 and wash by decantation three or four times. Ignite at a high 
 temperature and weigh as ZnO. Subtract the percentage of 
 ferric oxide found above. 
 
 Factor foi metallic zinc, 0.8034. 
 
 Factor for zinc chloride, 1.7644. 
 
 Free Acid.- — ^Dissolve 10 grams of the fused chloride in 100 c.c. 
 of distilled water, and test with methyl orange. If free acid is 
 present, which is rarely the case, determine by titration with 
 standard alkali. Factor, chlorine from hydrochloric acid, 0.973. 
 
 Total Soluble Chlorine. — Titrate 25 c.c. of the solution with 
 standard silver nitrate, using potassium chromate as indicator. 
 Subtract the amount of chlorine equivalent to the free hydro- 
 chloric acid present, if any, and also the chlorine combined as 
 ferric chloride, and calculate the remainder to zinc chloride, 
 by using the factor 2.04. The amount of zinc chloride thus 
 obtained should check with that found from soluble zinc. 
 
 RECORDS ON THE LIFE OF TIMBERS 
 
 Mine Timbers. — The U. S. Forest Service treated a large num- 
 ber of mine timbers according to various methods and placed 
 
APPENDICES 
 
 299 
 
 them in the coal mines of the Philadelphia and Reading Coal 
 and Iron Company at Pottsville, Pa. Inspections were made 
 
 Description of Material 
 
 Oondrtion of Material 
 
 Condition 
 
 of 
 
 Timber 
 
 G-reeii 
 Unpeeled 
 
 Seasoned 
 Peeled 
 
 Seasoned 
 Peeled 
 
 Green 
 Peeled 
 
 Green 
 
 Peeled 
 
 Seasoned 
 Peeled 
 
 Green 
 Peiled 
 
 Seasoned 
 Peeled 
 
 Green 
 Pesled 
 
 Seasoned 
 Peeled 
 
 Green 
 Peeled 
 
 Green 
 Peeled 
 
 PcrderyativB Used 
 
 Sold Aa 
 
 Coal Tar 
 
 Creosote 
 
 Arenariua 
 Oarbolineum 
 
 Sodium & 
 
 Magnesium 
 
 Chloride 
 
 (15% Solution) 
 
 Zinc 
 
 Chloride 
 
 (6^ Solution) 
 
 Zinc 
 
 Chloride 
 
 (6% Solution) 
 
 Water Gas 
 
 Tar 
 
 Creosote 
 
 Water Gas 
 
 Tar 
 
 Creosote 
 
 Coal Tar 
 Creosote 
 
 Coal Tar 
 Creosote 
 
 Coal Tar 
 Creosote 
 
 Zinc 
 
 Chloride 
 
 (2^t Solution) 
 
 Amount 
 PerCu.Ft. 
 
 , .5Lb. 
 (iJiGala. 
 Per Set) 
 
 .5 Lb. 
 m Gals. 
 Per Set 
 
 ILb. 
 Dry Salt 
 
 Dry Salt 
 
 J^Lb. 
 Dry Salt 
 
 3 Lbs, 
 Dry Salt 
 
 Method 
 
 of 
 
 Application 
 
 Untreated 
 
 Brush 
 
 Treatment 
 
 2 Coats 
 
 Brush 
 
 Treatment 
 
 2 Coats 
 
 Open Tank 
 Process 
 
 Open Tank 
 Process 
 
 Open Tank 
 Process 
 
 Open Tank 
 Process 
 
 Open Tank 
 Process 
 
 Open Tank 
 Process 
 
 Open Tank 
 Process 
 
 Bethel 
 Process 
 
 Burnett 
 Process 
 
 Years 
 Service v% 
 
 mji 
 
 C 
 
 Legend 
 
 ■ Sound 
 
 ^ Partly Decayed, Still SerriceaWe 
 
 ^ Entirely Decayed^ to be Bejuoved, not Seirlceable 
 
 U Eemovals Due to all Ciuises 
 
 Fig. 30. — Comparative condition of treated and untreated loblolly pine 
 gangway sets placed in the mines of the Philadelphia and Reading Coal 
 and Iron Co. 
 
 each year for 4 years with the results graphically shown in 
 Fig. 30.1 
 Paving Blocks. — ^In January, 1910, the American Association 
 
 > Bulletin 107, U. S. Forest Service. 
 
300 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 1 II 
 
 
 1 
 
 
 
 
 
 Li. 
 
 1 
 
 t 5 1 
 1 = 1 1 
 a ^ 1 
 
 Brusli-l Coat 
 
 ' 1 Coat 
 » 2 Coats 
 
 ICoat 
 t> 2 Coats 
 
 '» 1 Coat 
 " 2 Coats 
 
 ' 1 Coat 
 " 2 Coats 
 
 " 2 Coats 
 Open Tank 
 
 1 
 
 o 
 
 1 
 
 ■s 
 
 a> 
 
 < 
 o 
 
 Coal Tar 
 Creolin 
 
 Wood Creosote 
 
 i.P.F. Carbolineun 
 
 Arenarius t» 
 
 Coal Tar Creosote 
 
 n 
 
 Condition 
 
 before 
 Ire at meat 
 
 Green 
 
 Seasoned 
 
 Green 
 Seasoned 
 
 
 
 
 
 
 
 ■ r 
 
 ■ ■ 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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 M ft 
 
 1^ 
 
 ,=3 
 
 n 
 
 
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 .a U 
 o I 
 
 M 
 
APPENDICES 
 
 301 
 
 of Creosoted Wood Blocks Paving Manufacturers sent inquiries 
 to various American cities to learn their experiences with wood- 
 block paving. The replies are suminarized in Table 41. 
 Table 41. — Experience of Some Cities with Wood-block Paving 
 
 City 
 
 Years of service 
 at last inspec- 
 tion. 
 
 Condition 
 
 Authority 
 
 Brooklyn 
 
 7 
 31 
 8 
 7 
 5 
 4 
 9 
 5 
 9 
 
 Good 
 
 Blocks good 
 No repairs 
 Excellent 
 No repairs 
 No repairs 
 No repairs 
 No repairs 
 Excellent 
 
 J. C. Sheridan 
 R. E. Slade 
 E. R. Button 
 J. C. TravHIa 
 T. F. McGilvray 
 J. MacVicar 
 G. W. Touson 
 R. H. McCormick 
 L. W. Anderson 
 
 New Orleans 
 
 Minneapolis 
 
 St. Louis 
 
 Duluth 
 
 Des Moines 
 
 Toledo 
 
 Detroit 
 
 Grand Rapids, Mich.. . 
 
 Poles. — About 1000 chestnut poles treated in various ways 
 were set by the U. S. Forest Service in 1905 in cooperation with 
 the American Telephone and Telegraph Company in Pennsyl- 
 vania. The results after 5 years of service are shown in Fig. 31.^ 
 
 Descript'ion of Experiment 
 
 Preservative Hsed 
 
 Method 
 
 of 
 Treating 
 Material 
 
 Character 
 
 of 
 
 Ground 
 
 where Set 
 
 
 Sold as 
 
 
 
 Untreated 
 
 Brush 
 I >> 
 Charred 
 
 Sand 
 
 landy Loam 
 
 Crushed 
 
 Stone 
 
 laudy Loam 
 
 
 
 
 
 
 
 ^^^ 
 
 
 
 
 
 
 
 apiritfclne 
 AvenariuB Carbolineui 
 
 
 
 
 ■^" 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 m^ 
 
 
 0.5 1.0 1.5 2.0 
 
 Average Loaa in Oircumferance at Ground Line-Inches 
 
 Fig. 32. — Condition of experimental poles in the Poughkeepsie-Newton 
 Square line 8 years after placement. 
 
 A similar line was set up by the U. S. Forest Service in New 
 Jersey in 1902. All the poles were chestnut. The results after 
 8 years of service are shown in Fig. 32.^ 
 
 The German government has kept record on the life of its 
 poles when treated by various processes, these records extending 
 over a period of about 50 years. The general results to date are 
 shown in Table 42.' 
 
 ' Circular 198, U. S. Forest Service. 
 2 Circular 198, U. S. Forest Service. 
 ' Archiv fiir Post und Telegraphie. 
 
302 THE PRESERVATION OF STRUCTURAL TIMBER 
 
 
 
 
 
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APPENDICES 
 
 303 
 
 Cross Ties. — The reported life of cross-ties in service is given 
 in Table 43, which is taken from Bulletin 118 of the U. S. Forest 
 Service. 
 
 Table 43. — Reported Life of Ties in Service 
 
 Species 
 
 Laid by 
 
 How treated 
 
 Life 
 
 White oaks.. 
 
 Spruce 
 
 Pine (probably 
 western yel- 
 low, longleaf, 
 and pin on 
 pines). 
 
 Baltic pine . . 
 
 Hemlock 
 
 Tamarack. . . 
 Beech 
 
 Maple 
 
 Red oaks 
 
 Duluth & Iron Range Ry. Co. 
 
 Union Ry. Co. (horse) 
 
 [A., T. &S. F. Ry. Co 
 
 ] T. & N. O. Ry. Co 
 
 [ H. &T. C. Ry. Co 
 
 English railroads 
 
 C. R. R. of N. J 
 
 C, R. I. & P. Ry. Co 
 
 Duliith & Iron Range Ry.Co, 
 do 
 
 \ Pittsburg, Ft. Wayne & Chi- 
 cago Ry. Co. 
 French, German, and Aus- 
 trian railroads 
 
 I C. R. R. of N. J 
 
 I, German railroads 
 
 ' Wabash R. R 
 
 French and German railroads 
 
 Untreated 
 Burnettized 
 
 do.... 
 
 do .... 
 
 Creosoted 
 
 do.... 
 
 do.... 
 
 Wellhouse 
 Burnettized 
 
 do.... 
 
 Wellhouse 
 
 I Untreated 
 Burnettized 
 Creosoted 
 Burnettized 
 
 do 
 
 do 
 
 Creosoted 
 
 Years 
 
 8 to 9 
 
 8 to 20 
 
 lOi to 15| 
 
 10 to 11 
 
 19 
 
 8 to 18 
 
 15i 
 10 to 15 
 8 to 10 
 
 9i 
 8.84 
 
 4 to 5 
 10 to 12 
 
 18 to 30 
 15 + 
 
 16 
 
 5 to 6 
 
 19 to 26 
 
INDEX 
 
 Abrasion, importance of, 25 
 
 protection of ties from, 141 
 Absorption, effect of density of wood 
 upon, 31 
 diflSculty in measuring, 116 
 measured by gages and scales, 
 
 103 
 variation in different woods, 138 
 of preservatives (see penetra- 
 tion) 
 A.C.W. process, description of, 59 
 Aczol, description of, 253 
 Adzing, advantages of before treat- 
 ment, 147 
 machines, apparatus and cost 
 of, 106 
 Air pressure, effect of upon treat- 
 ment, 112 
 pumps, cost and use of in plants, 
 
 97 
 seasoning, description of, 44 
 Alkaline soils, action upon wood, 26 
 
 soils, decay of wood in, 221 
 Allardyce process, description of, 63 
 Allis-Chalmers Co., table on plant 
 
 costs, 125 
 American Ry. Eng. Ass'n, specifica- 
 tions for creosote, 83, 261 
 Ammonium chloride, as a fire retard- 
 ant, 216 
 Analysis, of creosote, 261 
 of zinc chloride, 297 
 Anchors, construction of, 93 
 Angier, F. J., on the use of air 
 pumps, 97 
 on grouping ties, 138 
 Annual ring, definition of, 34 
 Asbestos packing, use of in doors, 94 
 Association for Standardizing Pav- 
 ing Spec, specifications for 
 creosote, 84 
 
 305 
 
 B 
 
 Bailey, I. W., experiments of, on 
 
 penetration, 38 
 Bark, necessity for peeling, 41 
 
 effect of on life of piling, 183 
 Barrels, used for open tank plants, 
 
 89 
 Barns, paving blocks in, 204 
 Bateman, E., method for analyzing 
 
 zinc chloride, 74 
 Bethell process, description of, 56 
 Birds, destruction of wood caused 
 
 by, 27 
 protection against, 221 
 Bleeding, of wood blocks, 201 
 Block signals, use of treated ties 
 
 between, 241 
 Blocks, equipment for making, 105 
 
 oU for, 84 
 B.M. Process, description of, 249 
 B.M. Preservative, description of, 
 
 253 
 Boats, preservation of, 186 
 Boiling, effect of on strength of 
 
 wood, 229 
 Boiler house, construction of, 98 
 Boiling process, description of, 57 
 Bolts, use of in doors, 94 
 Bolt doors, construction of, 94 
 Borax, as a fire retardant, 216 
 Boring ties, machines for, 106 
 
 effect of, in holding spikes, 146 
 Boring, holes in posts to preserve 
 
 them, 175 
 Boucherie process, for treating poles, 
 
 163, 
 Bridge timbers, substitutes for, 246 
 Brush treatments, description of, 51 
 Brush treatments, for poles, 160 
 
 for posts, 175 
 Buehler process, description of, 68 
 Buggies, (see cars) 
 
306 
 
 INDEX 
 
 Buildings, methods of treating lum- 
 ber in, 209 
 substitution for wood in, 247 
 Builders, of treating plants, 261 
 Burlap, used in protecting piling, 183 
 Burnett process, description of, 60 
 Burnett, Wm. 73 
 
 Butterfield, J. T., tests on the elec- 
 trical resistance of wood, 
 234 
 
 C 
 
 Canals, use of in plants, 100 
 Capital, invested in wood preserv- 
 ing plants, 2 
 Carbolineum, Avenarius, description 
 
 of, 252' 
 Carbolineum, S.P.F., description of, 
 
 252 
 Carbolic acid, toxicity of, 72 
 Carbon, in creosote, 121 
 Card process, description of, 61 
 Cars, construction of cylinder, 100 
 treatment of wood in, 209 
 substitutes for wood in, 247 
 C. A. Wood Preserver, description of, 
 
 262 
 Cell walls, absorption by, 32 
 Cement, used in protecting piles, 184 
 Charring, as a means of preserving 
 
 wood, 51 
 poles, 160 
 posts, 174 
 Checks, prevented by "S-irons" 158 
 Chemical composition of cell wall, 
 
 effect of on penetration, 39 
 Chicago Creosoting Co., design of 
 
 block plant, 106 
 Coal tars, discussion of, 78 
 Coal tar creosote, composition and 
 
 value of, 81 
 specifications for, 83 
 Coils, construction of in retort, 93 
 Compression, of wood in cylinder, 
 
 117 
 Concrete, poles set in, 160 
 Concrete ties, use of, 244 
 Conduits, substitutes for wood, 248 
 
 Conservation of timber, affected by 
 
 preserving wood, 2 
 Consumption of wood preservatives 
 
 in the U. S., 269 
 Copper sulphate, its value as a wood 
 
 preservative, 71 
 Copperized oil, description of, 262 
 Corrosion of steel, by preservatives, 
 
 68 
 Corrosion of spikes, in zinc treated 
 
 ties, 241 
 Cost, of pressure plants, 124 
 of treating ties, 160 
 of treating poles, 165 
 of treating cross arms, 170 
 of treating mine timbers, 192 
 of fireproofing wood, 218 
 of treating paving blocks, 202 
 of treating posts, 178 
 of treating piling, 185 
 of treating shingles, 207 
 Cranes, use of in plants, 100 
 Creo-resinate process, description of, 
 
 250 
 Creoaire process, description of, 261 
 Creoline, description of, 264 
 Creosotes, their value as wood pre- 
 servatives, 75 
 classification of, 77 
 Creosote, definition of, 76 
 evaporation of, 67 
 expansion of, due to tempera- 
 ture, 117 
 method of manufacture, 79 
 Creosote, pro cess, (see Bethell proc- 
 ess). 
 Creosote, as a fire retardant, 219 
 effect on the strength of wood, 
 
 230 
 effect on human skin, 82 
 list of manufacturers of, 264 
 specifications for, 261 
 Forest Service method of analy- 
 sis, 270 
 ■ Cresol-calcium process, description 
 of, 251 
 Cross arms, woods used for, 168 
 methods of seasoning, 168 
 manufacture of, 168 
 
INDEX 
 
 307 
 
 Cross arms, economy in treating, 171 
 cost of treating, 170 
 treatment of, 169 
 
 Crude oils, value of, as wood pre- 
 servatives, 75 
 
 Crude oil, for treating posts, 174 
 effect on strength of wood, 231 
 
 Crumby, J. J., on the life of posts, 
 179 
 
 Curtis, W. G., 57 
 
 Cutting Season, effect of, on treat- 
 ment, 140 
 
 Cylinder cars, construction gf, 100 
 
 Cylinders, (see retorts) 
 
 Cylinder, expansion of due to tem- 
 perature, 117 
 
 D 
 
 Decay, discussion of, 15 
 Decayed poles, reenforcement of, 164 
 Density of wood, effect upon pene- 
 tration, 31 
 Deterioration of timber, discussion 
 of factors, which cause, 15 
 Dipping treatments, description of, 
 52 
 posts, 174 
 Dock, construction of loading, 99 
 Doors, construction of in retorts, 94 
 Durability, of green and seasoned 
 wood, 43 
 of American timbers, 275 
 records on life of wood, 298 
 
 E 
 
 Economy, in treating ties, 151 
 poles, 166 
 posts, 178 
 piling, 186 
 mine timbers, 193 
 Egypt, history of wood preservation 
 
 in, 9 
 Electrolysis, in protecting piling, 
 
 184 
 Electrical, resistance of treated 
 
 wood, 234 
 Empty cell process, (See Lowry and 
 
 Rueping processes) 
 Errors, in operating plants, 116-120 
 
 Europe, history of wood preservation 
 
 in, 9 
 Evaporation, of creosote, 67 
 Expansion, of creosote due to tem- 
 perature, 117 
 
 F 
 
 Factories, paving blocks in, 204 
 
 treatment of wood in, 210 
 Fence posts, (see posts) 
 Fiber-saturation point, definition of, 
 
 44, 225 
 Final vacuum, effect of, 109 
 Fire-killed timber, utilization of, 8 
 Fire, destruction of wood caused by, 
 
 25, 213 
 in mines, 192 
 Fire protection, in plants, 105 
 Fireproof ed wood, objections to, 214 
 Fireproofing wood, theory of, 214 
 methods of, 215 
 chemicals used in, 216 
 tests to determine the efficiency 
 
 of, 217 
 cost of, 218 
 Fireproofing plants, list of, 259 
 Fir, used for cross arms, 168 
 Form, of ties, 131 
 Forest management, effect of wood 
 
 preservation upon, 3 
 Forests, composition of affected by 
 
 wood preservation, 3 
 Freight, decreased by seasoning 
 
 poles, 159 
 Full-cell process, (see Bethell proc- 
 ess) 
 Fungi, description and classification 
 
 of, 16 
 Furniture, methods of protecting 
 
 rustic, 211 
 
 G 
 
 Gerry, Eloise, experiments on tylo- 
 ses, 36 
 Guissani process, description of, 54 
 Goltra, W. F., on transfer tables, 99 
 Goltra process, description of, 260 
 Greeks, on methods of preserving 
 . wood, 9 
 
308 
 
 INDEX 
 
 Greenheart, for piling, 181 
 Greenhouses, treatment of wood in, 
 
 209 
 Grouping, value of, in ties, 139 
 Growth, effect, of upon treatment, 
 
 141 
 Gages, location and construction of, 
 
 92 
 use of, in measuring absorption, 
 
 103 
 Guard rails, construction of, 93 
 
 H 
 
 Hatt, W. K., tests on the strength of 
 spikes, 147 
 effect of various processes on 
 strength of ties, 233 
 Hasselman process, description of, 
 
 250 
 Heartwood, effect on penetration, 33 
 Hewn ties, (see ties) 
 Herodotus, on preservation of mum- 
 mies, 9 
 History, of wood preservation, 9 
 Holz-Helfer, description of, 253 
 Humphrey, C. J., toxicity test by, 65 
 Hunt, G. M., on Boucherizing poles, 
 163 
 
 Imperial Wood Preservative, de- 
 scription of, 254 
 
 Inflammability, of wood treated with 
 zinc and creosote, 219 
 tests to determine, of wood, 217 
 
 Initial absorption, difficulty in meas- 
 uring, 116 
 
 Insects, destruction of wood by, 18 
 in rustic furniture, 211 
 
 Inspector's laboratory, equipment 
 for, 104 
 
 Inspection, of treatments, notes on, 
 122 
 
 Isaacs, J. D., 57 
 
 K 
 
 Kempfer, W. H., on treating poles, 
 
 162 
 Kickback, significance of, 118 
 
 Kreodone, description of, 254 
 Kyanizing, description of process, 53 
 for poles, 163 
 
 Laboratory, need for an inspector's, 
 
 104 
 Lagging, the retort, advantages of, 95 
 
 treatment of, in mines, 192 
 Leakage, prevention of, in doors, 94 
 Liebig; on theory of decay, 15 
 Lightning equipment, in plants, 105 
 Limnoria, description of, 24 
 Loading dock, (see dock) 
 Locustine, description of, 254 
 Logs, effect of wood preservation 
 
 upon inferior, 8 
 methods of preserving, 211 
 Log cabins, methods of protecting, 
 
 211 
 Lowry process, description of, 59 
 Lumber, methods of treating, 208 
 
 M 
 
 Machine shop, construction of, 98 
 Marine borers, description of, 20 
 Measuring tanks, types of, 101 
 Mechanical abrasion, destruction of 
 
 wood by, 25 
 Mercuric chloride, its value as a 
 
 preservative, 71 
 Mine timbers, selection of, 188 
 
 manufacture of, 189 
 
 seasoning of, 189 
 
 methods of treatment, 190 
 
 durability of, 298 
 
 cost of treating, 192 
 
 economy in treating, 193 
 
 substitutes for, 245 
 Mines, danger of fire in, 192 
 Mixing tanks, construction of, 101 
 Moisture, distribution in posts, 65 
 
 effect of in wood on treatment, 
 140 
 
 method of determining in creo- 
 soted wood, 273 
 Mummies, preservation of, 9 
 
INDEX 
 
 309 
 
 N 
 
 National Electric Light Ass'n, analy- 
 sis of creosote, 264 
 specifications for water gas creo- 
 sote, 85 
 
 Nausitoria, description of, 21 
 
 Newlin, J. H., experiments in driving 
 spikes, 145 
 tests on shrinkage, 226 
 
 Nonpressure process, description of, 
 53 
 
 N. S., Special, description of, 254 
 
 O 
 
 Odor, of preservatives, 69 
 
 Oil, seasoning in, 48 
 
 Oils, crude, value of, 75 
 
 Oil tars, discussion of, 78 
 
 Operation, of plants, 89 
 
 Open tank process, description of, 54 
 
 Open tank plants, types of, 89 
 
 list of in U.S., 258 
 Open tank, treatments for poles, 161 
 Oxalic acid, as a fire retardant, 216 
 
 Packing, for retort doors, 94 
 Paint, on treated wood, 69 
 
 value of in preserving wood, 87 
 Palmetto, for piling, 181 
 Patents, list of, for preserving wood, 
 
 276 
 Pavements, efficiency of various, 197 
 Paving blocks, manufacture of, 105- 
 198 
 
 oil for, 84 
 
 troubles with, 200 
 
 expansion of, 201 
 
 methods of laying, 202 
 Paving blocks, cost of treatment, 202 
 
 history of, 195 
 
 woods used for, 197 
 
 number used, 196 
 
 methods of treatment, 199 
 
 advantages of, 203 
 
 for barns and factories, 204 
 
 durability of, 299 
 
 Penetration, of preservative, effect 
 of structure on, 31 
 effect of sapwood on, 33 
 effect of heartwood on, 33 
 in summerwood, 34 
 in springwood, 34 
 efiect of vessels upon, 35 
 effect of tyloses upon, 35 
 effect of resin ducts upon, 36 
 effect of pits upon, 38 
 effect of composition of cell wall 
 
 upon, 39 
 effect of cell slits upon, 39 
 of various preservatives in 
 wood, 70 
 Peeling timber, necessity for, 41 
 Peeling bark, necessity for, 37 
 Perforations, in poles to aid pene- 
 tration, 161 
 Petri dish, method for determining 
 
 toxicity, 65 
 Petroleum, (see crude oils) 
 Pettigrew, experiments with mum- 
 mies, 9 
 Pholas, description of, 22 
 Piling, life of, 16, 
 
 woods used for, 181 
 manufacture of, 182 
 methods of seasoning, 182 
 
 treatment, 183 
 cost of treating, 185 
 economy in treating, 186 
 substitutes for wood, 244 
 Piping, use of in plants, 104 
 Pitch streaks, in preserving posts, 
 
 177 
 Pits, effect on penetration, 38 
 Plants, construction and operation 
 of, 89 
 cost of pressure, 124 
 list of wood preserving in U. S., 
 255 
 Plates, bearing on ties, 141 
 Pliny, on Grecian methods of pre- 
 serving wood, 9 
 Pole borer, description of, 19 
 Poles, attacked by woodpeckers, 27 
 woods used in making, 156 
 manufacture of, 156 
 
310 
 
 INDEX 
 
 Poles, perforations in, 161 
 
 seasoning of, 156-168 
 
 selection of species for, 156 
 
 shrinkage in, 169 , 
 
 saving in freight due to season- 
 ing, 159 
 
 methods of treating, 159 
 reinforcing decayed, 164 
 
 cost of treating, 165 
 
 economy of treatment, 166 
 
 life of, 166-301 
 
 substitutes for, 244 
 Pollution, of streams, 122 
 Pores, (see vessels) 
 Posts, woods used in making, 172 
 
 method and time of cutting, 173 
 of seasoning, 173 
 
 treatment of, 174 
 
 cost of treating, 178 
 
 economy in treating, 178 
 
 life of, 179 
 
 substitutes for wood, 245 
 Powder post insects, description of, 
 
 18 
 Powell process, description of, 250 
 Preliminary vacuum, effect of, 107 
 Preliminary air, effect of, 112 
 Preservatives, corrosive action of, 68 
 
 properties of efficient, 64 
 
 purity of, 121 
 
 used in treating wood, 251 
 
 amounts used in U. S., 259 
 
 toxicity of, 66 
 Preservol, description of, 262 
 Pressure plants, essential parts of, 91 
 Pressure, effect of, on treatments, 
 
 115 
 Pressure, effect of, on strength of 
 
 wood, 232 
 Prince, R. E., on fireproofing woods, 
 
 216 
 Processes, for preserving wood, 50 
 Pump house, construction of, 96 
 
 R 
 
 Rails, construction of guard, 93 
 Receiving tanks, use of, 101 
 Records, on the durability of timber, 
 298 
 
 Resin ducts, effect upon penetration, 
 
 36 
 Retorts, construction of, 91 
 Retort house, construction of, 91 
 Robbins process, history of, 13 
 
 description of, 250 
 Roofs, on ties, value of, 135 
 Rueping process, description of, 60 
 Rutgers process, description of, 61 
 
 S 
 
 Sapwood, effect on penetration, 33 
 
 distribution on ties, 132 
 
 absorption by, 138 
 Sapwood Antiseptic, description of, 
 
 253 
 Sap stain, damage caused by, 29 
 
 protection against, 222 
 Sand storms, protection against, 223 
 Sawmill, in plants, 106 
 Scales, use of, in measuring absorp- 
 tion, 103 
 Season, of year, effect of on treat- 
 ment, 40, 140 
 Seasoning timber, necessity for, 42 
 
 effect on decay, 43 
 checking, 43 
 decreasing freight, 43 
 strength of wood, 224 
 
 methods used in, 44 
 
 in hot air, 46 
 
 in open air, 44 
 
 in saturated steam, 46 
 
 in superheated steam, 47 
 
 in oU, 48 
 
 in water, 48 
 
 ties, 197 
 
 poles, 168 
 
 mine timbers, 189 
 
 posts, 173 
 
 cross arms, 245 
 
 piling, 182 
 Seasoning yards, care of, 45 
 Seeley process, history of, 12 
 
 description of, 54 
 Shipworms, description of, 20 
 Shingles, woods used for, 205 
 
 method of treating, 206 
 
 treated against fire, 206 
 
INDEX 
 
 311 
 
 Shingles, cost of treating, 207 
 substitutes for wood, 247 
 
 Shower baths, use of for employees, 
 104 
 
 Shrinkage, in poles, 159 
 equations for, 226 
 
 S-rons, prevention of checking, 158 
 
 Signals, block, use of treated ties 
 between, 241 
 
 Silos, treatment of wood in, 209 
 
 Slits, effect of, in cell walls upon 
 penetration, 39 
 
 Slipperiness, in wood blocks, 200 
 
 Smith, C. S., on treatment of poles, 
 163 
 
 Sodium carbonate, as a fire retard- 
 ant, 216 
 
 Sodium fluoride, its value as a pre- 
 servative, 72, 253 
 
 Sodium silicate, its value as a pre- 
 servative, 252 
 
 Soil, effect of alkaline, upon wood, 
 26, 221 
 
 Specifications, for creosote, 261 
 for zinc chloride, 73 
 
 Spider doors, construction of, 94 
 
 Spikes, kinds, and use of, 143 
 use of screw, 146 
 
 Spirittine, description of, 252 
 
 Springwood, effect on penetration, 
 34 
 
 Square sets, treatment of, 191 
 
 Stains, value of, in preserving wood, 
 87 
 
 Steel, corrosion of, by preservatives, 
 68 
 
 Steel ties, use of, 243 
 
 Steam, seasoning in saturated, 46 
 superheated, 47 
 
 Steam coils, (see coils). 
 
 Steaming, effect on strength of wood, 
 226 
 
 Stone, poles set_in crushed, 160 
 posts set in crushed, 174 
 
 Streams, pollution of, 122 
 
 Strength of wood affected by seas- 
 oning, 43, 224 
 by preservatives, 70, 230 
 by crude oil, 231 
 
 Strength of wood affected by boil- 
 ing, 229 
 by pressure, 232 
 by various processes, 232 
 by temperature, 231 
 zinc chloride, 230 
 steaming, 226 
 of ties, 144 
 Storage tanks, use and construction 
 
 of, 101 
 Stubs, used for reinforcing poles, 164 
 Substitutes, for treated timber, 243 
 Summerwobd, effect of on penetra- 
 tion, 34 
 
 Tanks, construction of, 101 
 Tars, classification of, 77 
 Teesdale, C. H., experiments on 
 penetration, 37 
 on absorption of creosote by 
 wood, 230 
 Temperature, effect of on strength of 
 
 wood, 231 
 Teredo, description of, 21 
 Test tracks, need for, 154 
 Thermometer, location of in retort, 92 
 Thinning forests, effect of wood pre- 
 servation on, 7 
 Thilmany process, history of, 13 
 
 description of, 249 
 Tiemann, H. D., experiments in 
 penetration, 39 
 effect of temperature on wood, 
 
 231 
 tests on strength of wood, 224 
 Tie plates, types and use of, 141 
 Ties, selection of species for, 128 
 cost of treating, 150 
 crushing strength of, 144 
 durability of, 303 
 economy in treating, 151 
 form of, 131 
 grouping, to secure uniform 
 
 treatment, 136 
 hewn vs. sawed, 129 
 length of time to season, 135 
 peehng, 41 
 sawed, value of, 129 
 
312 
 
 INDEX 
 
 Ties, seasoning of, 134 
 
 selection of treating process for, 
 
 148 
 substitutes for wood, 243 
 Tillson, G. W., studies of street 
 
 pavements, 196 
 Timber supply, effect of wood pre- 
 serving on, 2 
 Timberasphalt, description of, 252 
 Toxicity, of preservatives, 65 
 Transfer tables, use of, 99 
 Track scales, use of, 103 
 Treated timber, amount of in U. S., 
 
 259 
 Turtles, (see anchors) 
 Tyloses, effect of, on penetration, 35 
 
 U 
 
 United States, history of wood pres- 
 ervation in, 11 
 
 Utilization, of top logs, caused by 
 wood preservation, 8 
 
 V 
 Vacuum, effect of in treating timber, 
 
 107 
 Vessels, effect of, on penetration, 35 
 Volume, of charge, difl&culty in 
 
 measuring, 116 
 Vulcanizing process, description of, 
 
 251 
 
 W 
 
 Waste, in hewing ties, 130 
 Water-gas-tar creosote, derivation 
 and composition of, 85 
 
 description of, 253 
 
 specification for, 85 
 Water-gas tar, (see oil tars) 
 Water, its existence in wood, 43 
 
 in oil, 121 
 
 soaking wood in, 48 
 Wellhouse process, description of, 62 
 Winslow, C. P., on creosotes, 75 
 Winter, effect of, on cutting timber 
 
 in, 40 
 Wood-block paving, oil used for, 84 
 Wood creosote, description of, 253 
 Wood, effect of water in on strength, 
 43 
 
 Wood, expansion of due to tempera- 
 ture 120 
 
 Wood louse, description of (see 
 Limnoria) 
 
 Wood preservation, definition of, 1 
 
 Wood preserving industry, impor- 
 tance of, 1 
 
 Wood preserving plants, list of in 
 U. S., 255 
 builders of, 261 
 
 Woodpeckers, destruction of wood 
 by, 27 
 
 Wood tars, discussion of, 79 
 
 Wood tar creosote, derivation and 
 composition of, 86 
 
 Working tanks, use of, 101 
 
 Wyoming Experiment Station, tests 
 on posts, 175 
 
 X 
 
 Xylotrya, description of, 20 
 
 Yard, arrangement of, 99 
 care of, 45 
 
 method of handling timbers in, 
 100 
 Yarborough, R. W., on lagging 
 
 retorts, 96 
 Year, effect of time of, on treatment, 
 40 
 
 Zinc chloride, as a fire retardant, 219 
 changes in solutions, 122 
 effect upon the strength of wood, 
 
 230 
 its value as a preservative, 72 
 manufacturers of, 254 
 method of analyzing, 297 
 
 in wood, 74 
 specification for, 73 
 visual tests for, 74 
 Zinc chloride process, (see Burnett 
 
 process), 
 Zinc tannin process, (see Wellhouse 
 
 process) 
 Zon, R., on the manufacture of ties, 
 130.