A PRACTICAL TREATISE ON THE RAW MATERIALS AND FABRICATION OF GLUE, GELATINE, GELATINE VENEERS AND FOILS, ISINGLASS, CEMENTS, PASTES, MUCILAGES, ETC., BASED UPON ACTUAL EXPERIENCE. BY F. DAW1DOWSKY, TECHNICAL CHEMIST. TRANSLATED FROM THE GERMAN, WITH EXTENSIVE ADDITIONS, INCLUDING A DESCRIPTION OF THE MOST RECENT AMERICAN PROCESSES, BY WILLIAM T. BRARNT, GRADUATE OP THE ROYAL AGRICULTURAL COLLEGE OF ELDENA, PRUSSIA. ILLUSTRATED BY THIRTY-FIVE ENGRAVINGS. PHILADELPHIA: HENRY CAREY BAIRD & CO., INDUSTRIAL PUBLISHERS, BOOKSELLERS, AND IMPORTERS, 810 WALNUT STREET. LONDON: SAMPSON LOW, MARSTON, SEARLE & RIVINGTON, Crown Buildings, 18S Fleet Street. 1884 . COA)S rP 76 ? DO-6 /J / ??'/• Copyright by HENliY CAREY BAIRD & CO. 1SS4. COLLINS, PRINTER. THE GETTY CENTER LIBRARY PREFACE. The importance of glue and gelatine, by reason of their constantly-increasing consumption in the arts and for culinary and medicinal purposes, has rendered necessary some instruction relative to their manufac¬ ture. In the multitude of books, treating of every conceivable subject and matter, which have issued from the prolific press of the United States during the last ten years, there is none which treats of this impor¬ tant branch of industry. The only information in regard to it is scattered through encyclopedias, chemi¬ cal books, etc., difficult to find and troublesome to study. The object of this work is to present to the reader, in a handy and comprehensive form, complete informa¬ tion regarding the subject. The work upon which the book is mainly based is an excellent one, and has met with great success in Germany, it being thoroughly practical and easily comprehended by the ordinary workman. Like nearly every other branch of industry, the manufacture of glue and gelatine has lately made great progress towards perfection. Ingenious and practical men have devoted their energies to actual IV PREFACE. experiments, and the aid of chemistry has been invoked until the manufacture has been lifted from the slough of stagnation, into which it was sunk for so many years, to the position of a great industry, carried on in immense establishments, and giving employment to a lanje number of workmen. In the following pages will be found the principal improvements in machinery and manufacture up to the present date, due regard having been given to the present advanced American practice, as well as a description of the various and numerous uses of the manufactured pro¬ duct, and full instructions for preparing the com¬ pounds of which it forms a constituent. To make the book still more acceptable to the manufacturer, mechanic, artisan, and artist, for whom it is especially intended, a treatise on the manufacture of cements and pastes has been added. Great care has been used in selecting the receipts, and only such have been given as have stood a prac¬ tical test and can be recommended. Many of the receipts are entirely new. The entire work has been compiled with a view to practical utility, so that whether the article to be mended is a fine China vase or a defective iron casting, a suitable cement will, by referring to the following pages, be readily found. W. T. B. Philadelphia, April 21, 1884. CONTENTS. I. Wiiat is Glue. PAGE Sources of Glue ; Materials richest in Glue-yielding sub¬ stances ......... 25 Glue, the product of several transformations ; Distinction of the various transition stages of Glue ... 26 Glue-yielding substance; Crude Glue; Jelly; Glue; Characteristics of Glue . . . .. . .27 Glutin; Chondrin; Pure Glutin . .... 28 Aqueous solution of Glutin, how precipitated . . 29 Dehydration of Glutin ; Gonnor’s experiment in reducing the size of a print; Chondrin and its precipitation . 30 Chemical composition of Chondrin ; Leucine ; Glycoeoll; Properties of Glue, and its behavior towards other sub¬ stances . . . . . . . . .31 The behavior of Glue-solution towards different salts . 32 Tannic Acid a valuable test of the presence of Glue . 33 Chemical composition of Glue; Chemical composition of Isinglass . . . . . . . . . 34 Tests for Glue; Bisler-Beumat’s process . . .35 Lippowitz’s Process for testing Glue . . .37 Results obtained in examining different Glues by Lippo- witz ..38 Table of results of tests by the foregoing methods . 39 Facts shown by the previous table .... 40 Testing the Strength and Tenacity of Glue . . .41 1* * VI CONTENTS. II. Raw Materials and Manner of Preparing them for the Manufacture of Glue. page Animal Skin ; The Corium or Cutis ; Mode of trimming by Tanners .••••••• ^3 Value of the refuse from Tanneries .... 44 Danger of the refuse being spoiled .... 45 Freeing the Glue stock from Lime 40 W. A. Hoeveller’s Glue Stock Washer . . . .47 Arrangement of work in a Factory .... 52 Manner of treating Fresh Waste ..... 53 Bones and Cartilages, their composition ; Sorting of Bones 54 Crushing Bones in a mill; Steaming the Bones . . 55 Use of Lime Bath ....... 56 Freeing the Bones from Acid ; Gcrland’s use of Sulphu¬ rous Acid . . . • • • • • .57 Leather waste ; How to select and treat it 58 Preparation in the Hollander, etc. .... 59 Raw materials for Fish Glue; Isinglass and how to pre¬ pare it 60 III. Fabrication of Glue. Boiling Glue . . • • • • • . G2 Description of Boiler; Use of Straw 03 Directions for successful Boiling ..... G4 Clarification of Glue . . • • • • .65 New Process for Glue Boiling ..... G6 Classification of Glue . . • • • • .67 Precipitation of the Lime . • • • • .68 To free the Gelatinous Solutions from coloring substances 69 Use of Sulphurous Acid in producing entirely colorless Glue Moulding the Glue . • • • • • .71 CONTENTS. VI1 PAGE Cutting the Cubes of Glue ...... 72 Drying the Glue . . . . . . .73 Construction of the Drying-Room ..... 74 Temperature of the Drying-Room ..... 75 W. A. Hoeveller’s Apparatus for Drying Glue . . 76 Use of Epsom and Glauber’s Salt for withdrawing water from Gelatinous- Cakes ; Defects and Advantages of this process ........ 80 A more suitable plan for the same purpose . . .81 IV. Plan and Arrangement oe a Glue Factory. Description of the required Plant and Utensils . . 82 Choice of Location ....... 83 Arrangement of the Factory ...... 85 Construction of Lime Vats ...... 86 Comminution of Rones ...... 87 Vats for converting Stock into Jelly .... 88 Construction of the Drying-Room .... 89 Sketch illustrating arrangement of rooms ... 90 Machines and Apparatus used in a Glue Factory . . 92 Apparatus for crushing the Bones; Extracting the Fat . 93. Use of Benzine for freeing Bones from fat; Use of Liquid Hydrocarbon for freeing Bones from fat; Patent pro¬ cess of Messrs. Win. Adamson and Chas. F. A. Simonis, of Philadelphia, for the treatment of Animal and Vege¬ table Substances with Hydrocarbons for the purpose of extracting therefrom oily, fatty, and resinous matter 94 Adamson’s Method for treating substances with Hydro¬ carbon Vapor for the purpose of extracting Oils, Fats, etc.98 Adamson’s Method for treating substances with Liquid Hydrocarbon for the purpose of extracting Oils, Fats, etc.101 CONTENTS. viii PAOE Adamson’s Process for removing Hydrocarbons from sub¬ stances which have been treated therewith . . .104 Benzine Process as patented by F. Seltsam . . .108 Convenient Apparatus for boiling Waste into Glue, adapted for small establishments . . . .110 Plan of Manufacture pursued in all extensive Glue Fac¬ tories . . . • • • • • .112 Illustration and description of a Vat . . . .113 To keep the Jelly liquid during Clarification . .114 Use of Sulphurous Acid and how to develop it; Appara¬ tus of Dr. Bruno Terr.e of Mass, for development of Sulphurous Acid . . . . . . .115 Instrument to indicate amount of dry Glue in a solution 118 Discharging the solution into Cooling Boxes . . .119 Tools for cutting Jelly into Cakes ; Sehneible’s Machine for slicing and spreading Glue Jelly preparatory to drying . . . . . . . . .120 M. Devoulx’s Cutting Machine . . . . .123 Drying Nets . . . . . . . .126 Use of horizontally stretched wires; Frames for placing Nets . . . . . . . . .127 Y. Gelatine and its Preparation. Gelatine, its uses, and the raw material for its manufac¬ ture . . . . . • • • • .128 Solution of the Glue Cartilage and the amount of solid Gelatine yielded by Bones ..... 129 D. J. Briers’s Method of preparing Bone Glue ; Descrip¬ tion of Apparatus . . . . . . .130 Illustration of Apparatus . . . . . .131 Preparation of the Bones ; Reduction of the Bones . 138 Extracting the Jelly ....... 139 Evaporation of the Gelatinous Solutions . . . 140 CONTENTS. ix PAGE Modern process of preparing Gelatine . . . .142 Preparation of the finished Gelatine . . . .143 Fabrication of Gelatine according to Dr. Schwarz . .144 Jullion’s and Pirie’s Method of preparing Bone-Glue . 146 Hagen’s and Seltsam’s Process of preparing Bone-Glue . 14 7 VI. Uses of Glue and Gelatine. Use of Glue as a Cement ...... 148 Use of Glue as an Agglutinant . . . . . . 149 Glue in Sizing and Dressing . . . . . .150 Glue for Culinary and Medicinal purposes . . .151 Use of Glue for Elastic Mas’ses and as a partial substitute for Caoutchouc . . . . . . . .153 Use of Glue for Fancy Articles . . . . .154 VII. Different Varieties of Glue and Gelatine, and Special Directions for their Preparation. Joiner’s Glue . . . . . . . .155 How to make and use Glue ...... 156 Holding power of Glue ; Cologne Glue .... 158 Russian Glue . . . . . . . .159 Patent Glue . . . . . . . . .160 Gilder’s Glue; Size Glue and Parchment Glue; Paris Glue.161 A new Glue size for paper-makers’ use . . . .162 New substitute for Glue Size ..... 163 Parementine or Policolle ; New Size .... 164 Manufacture of Glue Size ; Process of G. J. Lesser, of Frankfort, Germany . ... . . . .165 Liquid Glue ; Receipts for keeping Glue Solutions liquid 167 Steam Glue; Russian Steam Glue ; Pale Steam Glue; Dark Steam Glue ; Chrome Glue 169 X CONTENTS. PAGE Glue for Attaching Leather to Metal . . . .170 Glue for Leather, Paper, etc. ; Glue for Parchment Paper in making Sausage Skins.171 Tungstic Glue ; Indestructible Mass for the Manufacture of Ornaments, Toys, etc. . . . . . .173 Compound for Billiard Balls; Mouth Glue . . .174 Water-proof Glue ; Process of Coloring Glue ; Process of G. J. Lesser, of Frankfort, Germany, for Coloring Glue . . • • • ■ • • .175 Prevention of the Cracking off of Glue; Glue for the Clarification of Wine and Beer . . . . . 17G Gelatine Capsules for medicinal purposes; Court Plaster 177 Gelatine Veneers, Preparation of the Plates . . .178 Preparation of the Glue Solutions . . • .179 Imitations of Enamels; Imitations of Pearl Veneers . 181 Essence d’ Orient . . . • • ■ * .182 Pouring the Colored Solutions of Glue upon the plates . 183 Imitations of Malachite . . • • • .184 Transferring the Layer of Glue to a Layer of Gelatine . 185 Drying and Detaching the Veneers .... 18G Gelatine Foils, their Manufacture and Coloring . .188 Imitation of Marble . . . • • • .189 Elastic Glue for Printers’ Rollers.190 Isinglass and its Substitutes . . . ' . • .191 Leaf Isinglass; Book Isinglass.192 Tongue Isinglass; Ribbon Isinglass; Thread Isinglass; Russian Isinglass ; Siberian purse Isinglass ; Samovey Leaf. ..193 Russian Mode of preparing Isinglass . . . .194 North American or New York Isinglass ; East India Isin¬ glass . . • • • • • • .195 Hudson Bay Isinglass; Brazilian Isinglass . . .196 German Isinglass; Rohart’s Substitute for Isinglass, Ichthyocholle Frangaise.197 CONTENTS. XI PAGE Substitute for Animal Isinglass; “Chinese Isinglass;’’ Japanese Agar-Agar . . . . . . .198 Artificial Isinglass . . . . . . .199 VIII. Cements and Pastes. Strohmann’s Classification of Cements and Pastes . . 200 Term Agglutinant or Paste, application of; Division of Cements according to the bodies to be cemented . 201 Chemical Nature of Cements ; Oil Cements . . . 202 Resinous Cements ....... 204 Caoutchouc and Gutta-Percha Cements .... 206 Glue and Starch Cements ; Lime Cements . . . 207 Oil Cements; Glaziers’ Putty ..... 208 Litharge Oil Cement; Minium Oil Cement . . . 210 Zinc Oil Cement . . . . . . . .211 Mastic Cement, Mastic or Pierres de Mastic . . .212 French Mastic; Paget’s Mastic; Cement for Wash¬ basins . . . . . . . . .213 Water-proof Linseed Oil Cements ..... 214 Serbat’s Linseed Oil Mastic . . . . . .' 215 Stephenson’s Oil Cement ; Alum Oil Cement . .216 Oil Cement for Glass ; Oil Cement free from Lead for Steam Pipes; Oil Cements for Steam Pipes . .217 Oil Cement for Marble; Linseed Oil Cement for attach¬ ing Metal Letters to Glass ; Linseed Oil Cement for Metal.218 Oil Cement for Porcelain; Diamond Cement ; Hager’s Diamond Cement; Resinous Cements ; Resinous Ce¬ ment for Amber . . . ... . .219 Resinous Cement for Turners; Resinous Cement for Ivory and Rone; Resinous Cement for White Enamelled Clock Faces; Resinous Cements for Glass 220 CONTENTS. xii PAGE Resinous Cement for Glass upon Glass ; Resinous Cement for Glass upon Metal; and for Metal Letters upon Glass, for Wood Resinous Cements for Knife Handles; for Petroleum Lamps, for Porcelain, for Porcelain which is to be heated Shellac and Petroleum Cement; Resinous Cement for Horn, Whalebone, and Tortoise Shell; Best Cement for Tortoise Shell ...•••• Cement for Terra-Cotta Articles; Mastic Cement for Glass ....••••• Stick Mastic Cement; Sulphur Porcelain Cement; In¬ soluble Resinous Cement for Wooden Vessels ; Cement for Bottle Corks • •••••• Caoutchouc Cements; Caoutchouc Cements for Glass Soft Caoutchouc Lime Cement; Hard Caoutchouc Cement; Marine Glue • ••••• Gutta-Percha Cements; Gutta-Percha Cement for Leather ; Cement for Hard Rubber Combs Elastic Gutta-Percha Cement; Gutta- Percha Cement for Horses’ Hoofs .••••••• Caseine Cements ; Preparation of Pure Caseine Caseine Cement which can be kept for a long time; Caseine Cement for Glass; Caseine Cement for Metals; Caseine Cement for Porcelain Caseine Cement for Meerschaum ; Caseine and Borax Cements for Wood, etc. . • • • • • Caseine Cement for Glass and Porcelain; Water-Glass and Water-Glass Cements ; Water-Glass . Water-Glass Cement for Cracked Bottles; Water-Glass Cement for Glass and Porcelain ; • Water-Glass Cement for tightening Joints of Pipes exposed to Red Heat . Water-Glass Cement for Uniting Metals, etc. ; Water- Glass Cement for Marble and Alabaster 221 222 223 224 225 226 227 229 230 231 232 233 234 235 236 CONTENTS. Xlll Glycerine and Glycerine Cements; Glycerine and Lead Oxide Cement ........ Lime Cements ; Lime and Chalk ..... Lime Oil Cement for Glass; Lime Cement for Joiners, etc. ; Lime Cement for Cracked Clay Crucibles and Porcelain . . . ■ Lime and Glue Cement; Gypsum Cements . Cement for Plaster-of-Paris Statues; Cement for Glass and Porcelain ........ Cement for Iron and Stone ; Plaster-of-P^ris and Alum Cement for Porcelain; Plaster-of-Paris and Gum Arabic Cement for Porcelain; Universal Plaster-of- Paris Cement ........ Iron Cements ; Iron Cement resisting Heat; Water and Steam-proof Iron Cement; Cement for Iron Fire-proof Cement for Iron pipes ; Iron Cements for high temperatures ........ Iron Cement for tilling in defects in Casts ; Iron Cement for Cracked Stove Plates, etc.; Iron Cement for Iron Water Tanks ; Iron Cement for Cracked Iron Pots Black Iron Cement for Stoves; Sehwatze’s Cements for Iron Stoves ........ Cements for Chemical Apparatus ..... Linseed Oil and Clay Cement; Linseed Oil, Zinc, and Manganese Cement; Clay Cement for very high tem¬ peratures ......... Cement resisting Acids ; Caoutchouc Cement for Chemi¬ cal Apparatus ; Scheible’s Cement for Chemical Appa¬ ratus ......... Cements for special purposes ; English Cement for Por¬ celain ; Cement for attaching Metallic Letters to Glass, Marble, Wood, etc. ; Cement for closing the Joints of Iron Pipes ........ Cement for uniting Leather and Metal; Cement for Leather Belting ....... 2 PAGE 23 7 238 239 240 241 242 243 244 245 246 247 248 249 250 251 XIV CONTENTS. Steam Boiler Cement; Turner’s Cement; Cement for Rubber ......... How to use Cements ....... Obstacles to the junetion of any two surfaces . IX. Pastes and Mucilages. Preparation of Paste ....... Starch Paste ......... Flour Paste . . * Means for preventing the spoiling of Paste Shoemakers’ Paste ....... Gum Arabic, Dextrine, and Tragacanth ; Gum Arabic; Dextrine ......... T. Blumenthal’s patented method for preparing Dextrine Tragacanth ; Pastes and Mucilages for special purposes ; Liquid Pastes Sugar and Lime Paste ; Liquid Sugar and Lime Paste . Improved Paste for Wall Paper ..... Paste for uniting Leather Straps; Pastes for Paper and fine Fancy Articles; Mucilage for Postage Stamps Mucilage to prevent the detaching of Postage Stamps and the opening of Envelopes, Fox’s Patent Paste for attaching Cloth or Leather to Table Plates ; Prevention of Mould in Mucilage; Very Adhesive Mucilage ......... Paste superior to Gum Arabic; Paste for Labels on Bot¬ tles, etc. ; Improved Gum Arabic Mucilage Strong adhesive Paste . ... Paste for attaching Labels to Metal; Permanent Paste ; Paste for Leather; Adhesive Gum from Phosphate of Alumina ... ....... A New Paste ........ PAGE 252 253 255 25G 257 258 259 260 262 264 265 266 267 268 269 270 271 272 273 274 CONTENTS. XV X. Present Status of the Fabrication of Glue. page Fabrication of Animal Charcoal and Bone Meal . .275 Production of Glue ; United States of America . . 277 Table of Glue Industry in the United States, as given by the census report of 1880 . . . . .279 France ......... 280 Belgium; England; Germany and Austria . . .281 Italy ; Sweden ; Denmark ; China and Japan . . 284 Index . 285 PRACTICAL TREATISE ON THE MANUFACTURE OF GLUE. i. WHAT IS GLUE? 1.—Sources of Glue. When certain substances contained in the animal organism are boiled for some time with water, the solu- © tion so obtained sets to a jelly on cooling. The result of drying the jelly will be a solid, brittle, glassy pro¬ duct, of a light-yellow to black-brown color, which is known as glue. The following materials, being richest in glue-yield¬ ing substance, are of the most importance to the glue boiler: Scraps of ox and other thick hides, the ten¬ dons and intestines of many animals; tissues of bones, cartilages, lymphatic vessels, buclcshorn, the swimming bladder of many fishes, fish scales, etc. Rabbit skins, deprived of their fur, scraps of parch¬ ment, old gloves, and many other apparently worse than useless matters, all contribute their quota in the manufacture of glue. 3 26 MANUFACTURE OF GLUE. Glue does not pre-exist in the animal organism, ex¬ cept under abnormal conditions, as a phenomenon of disease, but is the product of several transformations. The first of these takes place in drying the hide, as the result of boiling green hide prepared in the usual manner, by liming, etc., but not dried, will be an en¬ tirely different product of less consistency than that ob¬ tained by drying the hide after liming and then boiling. A second transformation seems to take place in boiling the material, and a third in drying the obtained jelly, which may explain the fact that the latter, which is not yet converted into actual glue, differs in its beha¬ vior from glue solution. The series of transforma¬ tions does not end even with the actual glue, for it is a well-known fact, that glue dissolved in water, and boiled for some time, does not gelatinize on cooling, but remains liquid. We have here to deal with an organic combination, differing from the more solid in¬ organic ones, by passing more quickly into decompo¬ sition, and more readily from one combination into another. 2.—Distinction of the Various Transition Stages of Glue. We distinguish therefore : — a. Glue-yielding substance. b. Crude Glue. c. Jelly. d. Glue. AVTIAT IS GLUE? 27 a. Grim-yielding substance is produced by the ani mal economy from proteine bodies, albumen, fibrine and caseine in a manner similar to that in Avhich new substances are formed in the ripening fruit by the transformation and separation into constituent parts of others previously present. b. By crude glue Ave understand glue-yielding sub¬ stance freed from all foreign matter, and physically prepared by drying. It forms an intermediate linlc between glue-yielding substance and jelly. We believe that, by reason of our experience, .we are justified in making this distinction between glue- yielding substance and crude glue. Lime carefully, for instance, fresh calves’ heads, such as the tanner cuts off after raising the skin, and then boil them Avithout previous drying, the result will be a turbid soup, containing, though everything be dissolved, no jelly whatever, or, at least, very little. c. Jelly is obtained by boiling the crude glue. Its adhesive power is far less than that of solution of finished glue, and it will become more quickly putrid than the latter. d. The finished product glue is, in most cases, not a definite chemical combination, but a mixture of sub¬ stances, Avith two of which scientific research has made us thoroughly acquainted. 8.—Characteristics of Glue. Independent of' impurities and accidental constitu¬ ents, glue consists of two distinctly distinguishable 28 MANUFACTURE OF GLUE. combinations, a, glutin , and b, chondrin , the former being formed from the hide and osseous parts, and the latter from the young bones, whilst yet in a soft state, and the cartilage of the ribs and joints. The manufacturer has it, of course, in his power to allow either of these substances to predominate in his product, but since experiments have shown glutin to possess much greater adhesive power than chondrin, it is advisable to separate as much as possible the car¬ tilaginous matter from other glue-yielding material. It is possible that a more careful study of chondrin may prove it to be possessed of qualities which would make the manufacture of it by itself desirable.* As an accurate knowledge of these constituents of glue is of the greatest importance to the manufacturer, we will here briefly state what scientific research has made known to us in regard to them. Pure glutin is obtained by submitting buckshorn, etc., to the action of water mixed with hydrochloric acid, until the calcium phosphate serving, so to sav, as a frame for the glue-yielding substance, is dissolved and only the glue cartilage remains behind. After freeing the latter from fat by steeping it in milk of lime and careful washing, it is boiled, and the result¬ ing jelly, when cold, mechanically distributed in cold water, in which it softens, but does not dissolve. By thoroughly stirring the mass the glutin yields its * It is now largely manufactured and used as a size.— Trans¬ lator. WHAT IS GLUE ? 29 coloring matter to the water, which must be replaced by fresh water until all coloring matter is extracted. Then pour off the water, and after dissolving the jelly in hot water, filter the solution through a cloth. By mixing the filtered solution with an equal volume of alcohol, a precipitate of pure glutin is obtained. When drv, pure glutin is almost colorless, transparent, hard, and endowed with great, but variable coherence according to the kind of material from which it is obtained. It is inodorous and insipid. Its specific gravity is greater than that of water. It exerts no influence whatever upon vegetable colors, and has a neutral reaction. It is insoluble in spirit of wine, ether, fat, and volatile oils. In cold water it softens, absorbing as much as 40 per cent., intumesces, be¬ comes opaque, but does not dissolve. A liquid which contains one-hundredth part of its weight of glutin be¬ comes viscous on cooling, but when it has only the one-hundred-and-fiftieth the menstruum remains fluid. An aqueous solution of glutin is precipitated by chlorine, platinum bichloride, tannin, and alcohol, but not by hydrochloric acid, acetic acid, sugar of lead, alum, and ferric sulphate. By dry distillation glutin gives ammonium carbonate, ammonium sulphide, am¬ monium cyanide, amines, pyridine bases, pyrol, and other compounds, and by boiling with dilute sulphuric acid, glycocoll and leucine, and other products. When heated, glutin diffuses a peculiar odor, enters into a state of semi-fusion, bends, tumefies, and then exhales the odor of burnt horn. In the air it takes 8 * 30 MANUFACTURE OF ULUE. fire with difficulty, smokes, flames only for a few min¬ utes, and leaves a bulky charcoal difficult to incinerate, the ashes of which consist principally of calcium phos¬ phate. Glutin, when in the jellied state, and treated with alcohol, undergoes a dehydration, under the influence of which it contracts greatly. It was by this means that Gonnor succeeded in reducing in a remarkable degree the size of a print obtained in a very hydrated film of glutin, and transferring it, so reduced, to stone, from which he obtained a new impression, quite simi¬ lar to the first, but more or less diminished. By taking these prints, on the contrary, w'ith glutin very little hydrated, and afterwards steeping them in water, a dilatation of the plate is obtained, which en¬ larges the figures with the same regularity. Pure cliondrin is prepared by boiling for from 24 to 48 hours the cartilages of the ribs, of the larynx with the exception of those of the epiglot, or of the windpipe and the bronchi. Chondrin is precipitated from its solution by spirit of wine. The precipitate is redissolved in warm water, evaporated, and dried. It forms a semi-trans¬ lucent mass of a slightly yellow color and resembles glutin as regards fracture and all external properties, but differs from it in being precipitated from it aqueous solution by mineral acids, sugar of lead, alum and ferric sulphate, and also by organic acids such as vine¬ gar, citric and oxalic acids, none of which precipitate WHAT IS GLUE ? 31 Chondrin, as regards its chemical composition, is poorer in nitrogen than glutin, and contains more sul¬ phur. Its formula approaches more closely that of albumen, which corresponds also with the origin of chondrin, for the cartilages may be considered as transition-links between the proteine and glue-yielding substances. By treating chondrin with sulphuric acid, it gives only leucine. By caustic potash it is transformed into glutin and yields then, like the latter, leucine and glycocoll. By boiling with concentrated hydrochloric acid, it yields a fermentable sugar to which the term chondroglucose has been applied. 4.—Properties of Glue, and its Behavior TOWARDS OTHER SUBSTANCES. Glue, as found in commerce, is always a mixture of glutin, chondrin, and other substances not yet accu¬ rately determined. Its quality depends on the crude glue and glue-yielding material used for the production of the jelly. We would here remark that even if the quantity of glutin contained in the various combinations could not be determined by scientific means, the product obtained from the different glue-yielding materials can be readi¬ ly distinguished by external characteristics. Every manufacturer knows that glue from hides differs from bone-glue in adhesive power, elasticity, and fracture, and that a larger yield of glue and of greater coherence 32 MANUFACTURE OF GLUE. is obtained from the glue-yielding tissues of old animals than from those of young and weak ones. Glue from fish-bladders and scales, though consisting mainly of glutin, differs materially in its behavior from hide or bone glue. Generally speaking, the jelly, no matter whether consisting of glutin or chondrin, possesses, before drying to glue, different properties from glue solution. It has less power of adhesion and spoils more quickly. At a temperature of 16° to 18° R. (20° to 22.5° C., 68° to 72.5° F.) jelly putrefies inside of 24 hours, smells of ammonia and decomposes, while glue solution can be kept much longer without suffering deterioration. The jelly absorbs ozone with avidity and is de¬ composed by it, this being the reason why an approach¬ ing thunderstorm may cause great damage by destroying the coagulating power of the glue soups, or causing the glue to turn on the nets, i. e ., to lose its con¬ sistency and become liquid and foul. The behavior of glue solution towards different salts also deserves attention. By adding potassium or sodium carbonate, neutral potassium tartrate, Rochelle or Epsom salts to a luke¬ warm fluid containing 15 to 20 per cent, of glue, the latter coagulates by the salt withdrawing the water from it. A lukewarm solution saturated with common salt, sal ammoniac, saltpetre, or barium chloride does not gelatinize. By adding to glue solution a large quantity of alum, the glue is precipitated as a transparent mass. WHAT IS GLUE? 33 Glue compounded with dilute hydrochloric acid does not gelatinize by itself, but will do so on adding com¬ mon salt. Boiling with slacked lime deprives glue solution of its power of gelatinizing, and changes it, on evapora¬ tion, into a gum-like colorless mass soluble in cold water and in saturated solution of common salt. By repeated boiling and cooling (for about six days), glue solution loses its property of gelatinizing. Tannic acid is a valuable and delicate test of the presence of glue. When added to a solution contain¬ ing only one-five-thousandth part of glue, nebulosity is immediately apparent. When more concentrated gelatinous fluids are treated with tincture or infusion of galls, a dense, white, caseous subsidence occurs, which, on desiccation, becomes brownish-yellow, agglutinates, and forms a hard brittle mass, easily reduced to powder, soluble in potash lye, but insoluble in water, ether, and spirit of wine. This precipitate is closely allied to the combination of tannin with skin which we call leather. Glue exposed to a dry heat melts, diffuses a dis¬ agreeable strong odor of burned horn, and leaves a charcoal having a powerful discoloring effect like ani¬ mal charcoal. By dry distillation it gives an aqueous solution of ammonium carbonate and a thick brown oil consisting of a mixture of ammonium carbonate, sul- phur, ammonium cyanide, etc. 34 MANUFACTURE OF GLUE. Chemically glue is composed of: — Per cent. Carbon ..... 49.1 Hydrogen . . . . .6.5 Nitrogen ..... 18.3 Oxygen and Sulphur . . . 26.1 which may be represented by the formula : C 12 H 10 N 2 O 4 . The composition of glue differs but little from that of the glue-yielding substance. Isinglass is composed of:— Carbon Hydrogen Nitrogen Oxygen Per cent. 49.5 6 9 18.8 24.8 This justifies the assumption that glue in its various transition stages does not represent different chemical combinations, but only modifications of one and the same combination distinguishable from each other by physi¬ cal characteristics, as is the case with starch, which, without suffering an alteration in its composition, appears as dextrine and grape-sugar, or as with cellulose, which, without altering its composition, can be transformed into amyloid and grape-sugar. WHAT IS GLUE? 35 5.—Tests for Glue. It is important that the manufacturer and dealer should know how to test the quality of glue. This can be accomplished either by ascertaining the per¬ centage of glutin by chemical means, or the adhesive power in a mechanical way. The percentage of glutin in a glue solution is esti¬ mated by precipitating it with tannin, filtering, drying, and weighing the precipitate, and by calculating from the amount of tannate of glue obtained (the composi¬ tion being taken in 100 parts at 12.74 parts of glutin and 57.26 of tannin) the quantity of pure glutin in the glue. Bisler-Beumat , while employing the same principle, prepares two normal fluids, one of which contains 10 grammes (0.35 oz.) of pure tannic acid to the litre (2.11 pints), while the other contains in 1 litre (2.11 pints) 10 grammes (0.35 oz.) of pure isin¬ glass and 20 grammes (0.7 oz.) of alum. As equal bulks of these fluids do not saturate each other, the author determines by titration the relation between them, and dilutes the tannic acid solution with the re¬ quisite quantity of water. In order to test a glue, he dissolves 10 grammes (0.35 oz.) of the sample to be tested with 20 grammes (0.7 oz.) of alum in a litre (2.11 pints) of water, heat being applied if necessary. Next 10 cubic centimetres (2.74 fluidrachms) of the tannic acid solution are taken to which an equal bulk of the glue solution is at once added, because one may be sure that this is not too much, as no sample of glue 36 MANUFACTURE OF GLUE. met with in commerce is as pure as isinglass. The vessels containing the mixed liquid being well shaken and the precipitate having settled, another cubic centi¬ metre (0.27 fluidrachm) of glue solution is added to the tannin solution, which is next filtered through a moistened cotton filter. If one drop of the glue solu¬ tion still produces a precipitate in the clear filtrate, another cubic centimeter is added to the tannin solu¬ tion, and then again filtered, these operations being repeated until the filtrate is no longer rendered tur¬ bid by the glue solution. According to numerous examinations made by skilled technologists, the quantity of glutin contained in different kinds of glue varies between 68 and 81 per cent. The chemical modes of testing glue give only the quantity of glutin contained in it, but do not prove that the substance combined with tannin corresponds to the actual adhesive power of the glue, for it is pos¬ sible that a glue containing a large quantity of glutin may possess but little adhesive power, and a jelly from which the glue is formed may contain an equal amount of glutin with the latter, but not possess yin equal power of adhesion. It is certain that the determination of the glutin alone is not a criterion of the quality of glue. In the absence of a reliable method of direct analysis, attempts have been made to deduce the quality of glue from indirect properties. One of these methods consists in immers'nsr the slue WIIAT IS GLUE? 37 to be tested in a large quantity of water at 12° R. (15° C., 59° F.) for a considerable time. The glue tumefies, absorbing 5 to 16 times its own weight of water. The more consistent and elastic the glue in this state is found to be, the greater its adhesive power, and the larger the quantity of water absorbed the more economical will the glue be in use. This method does not give thoroughly reliable results, and should only be employed with bone glue, as that obtained from animal offal does not behave in a similar manner. A more reliable method is to test the consistency of a gelatinized glue solution of known concentration at a determined temperature. Lippowitz has proposed the following method: After soaking 5 parts of the glue to be tested in water, dissolve it in sufficient hot water to make the weight of the solution equal to 50 parts. To gelatinize the solution keep it at 18° C. (64.4° F.) for 12 hours. To determine the degree of consistency place the obtained jelly in a cylindrical glass vessel. Place a piece of tin perforated in the centre across the top of the vessel. The hole in the tin should be large enough to allow of the ready passage of a stout iron wire. To the upper end of the wire is soldered a funnel, while the lower end is provided with a saucer-shaped piece of tin with the convex side turned downward and touching the surface of the jelly into which it is forced by loading the funnel with weights. The greater the consistency of the glue, the greater the weight which will have to be used. 4 38 MANUFACTURE OF GLUE. The following results have been obtained by com¬ parative experiments with this apparatus: — Variety of Glue. Weight required to force the saucer down. Breslau . . . . 1704 grammes (8.74 lbs.) Russian . . 1446 “ (3.18 “ ) Cologne . 1215 “ (2.67 “ ) Muhlhausen I . 727 (1.599 “ ) Nordlingen . . 724 (1.592 “ ) Muhlhausen II . 387.5 “ (0.85 “ ) The following results were obtained by testing glue by the previously mentioned methods :— WHAT IS GLUE ? 39 “a a a ® oi 03 *1 03 bC >£® 00 TJJ © © CO CO CQ •enxS jo sja'Bd g jCq sjtioq j-g at psqaosqB | O 1C (M O J> O COO 1C GOO O 1C 1 ^COH W C-1 CO COCO CO HW CO CQ •s^naa aad ui^ntQ 55.69 56.8 52.2 52.9 53.8 50.7 49.7 51.1 53.7 54.4 47.7 54.2 52.2 49.4 •ppu oiunei ^q paxeitdpa.ul e.tt; au[S jo sprad ooi 74.62 76.2 70.0 71.0 71.5 68.0 66.6 68.5 72.0 73.0 64.0 72.6 70.0 66.0 (■J o8bS oj o6£S) '0 oOSl J 03^ ^?s5i .—> bo co co > ^ - o^l ■5 s *0 ; fe rs 5? p*> 5 o & o o O Ph S ^ * T3 C c3 a? fl cS * CQ H 0 3 ■ 2 'S 0.2 ® a • Js a a ’So, o> . - % § >.1 ’ g c ,5 ■- * fl « | f- fe .5 tc 55 05 5 35 ® 03 « 03 JJ CD ^ Cfi So a" cd c5 ® -3 '■ 3 oi n ■pHpq - 2 J ^3 o ^ C § ~ s .2 § ^ pt “3 5 — ®" -0) z - 'So S be 3 p •" 2 be.S ’be cd a £ eS 43 O Of S £'®'f s-» • s fl.o c- c5 C 35 ■ &0 a od "n ■£ *5 ■£§• a „r '•2| 3 be ' ” « oT “ gs '5b ■ a £ o 1 -a a a 'co ^ a o c5 jj fs 32 t> c3 bo a ’? ‘5b CD h • S to • § "3 w> . 32 c— ^ a *g|l ■|'3j|'? bO-g CGrg g 3 a “S , •a o 0i3 ! WH 03 ( 05 O 33 co _CD 2 “s r 5’3 OW co Ph «Ph si . be w • w 1 a ^ §ll = o S 03 ^pq *4 a ■3 C o g bg’ ^35 -sr 2. .__ -iii •*-> > CO u >,.±4 >1 3 3 •3 £? i " 1 '-I 33 3 ®5 c3H O H(M COrtilOO cr O 40 MANUFACTURE OF GLUE. This table shows the following facts :— 1. The percentage of water in the 14 dry varieties of glue examined, varies between 9.0 and 21. The loss of water from isinglass is surprisingly large, especially as it cannot be explained by an artificial admixture of water, since the six varieties examined reabsorbed the same percentage of water from the air. The percent¬ age of water in the other varieties of glue differs but little. 2. The various varieties of glue required different quantities of tannic acid for their precipitation, the amount for 100 parts of glue varying between 66 parts and 76.2, or calculated to percents., between 49.4 and 56.8. •3. Placed in cold water, glue intumesces and ab¬ sorbs from 12 to 40 parts of water. The behavior of the various varieties differs very much in this respect, and in most of the experiments, with the exception of variety No. 4, the percentage of glutin is in exact proportion to the quantity of water absorbed. 4. The strength of the gelatinized glue varies be¬ tween 12 grammes (185.18 grains), and 64 grammes (987.67 grains), for a 10 per cent, solution. This property corresponds neither with the absorption of water nor the percentage of glutin. Variety No. 4, in the table, contains 52 per cent, of glutin, but does not gelatinize, its strength being therefore equal to 0, while variety No. 14, with 49.4 per cent, of glutin, therefore less than No. 4, shows a strength of 42. As no close connection between the WHAT IS GLUE? 41 properties mentioned in the table can be recognized, and as the strength and tenacity of glue do not always depend merely upon its amount of glutin, it has been proposed to test it by mechanical rather than chemical means. These consist in estimating the ad¬ hesive power of glue from the weight required to tear asunder two pieces of wood glued together and dried. But as the results obtained by this purely practical test, must necessarily vary on account of the impossi¬ bility of having the two surfaces of wood always exactly alike, and the uncertainty of applying every time the same quantity of glue, the following method has been devised. It consists in ascertaining the weight of force required to break a given bar of the material as compared with that used to break a speci¬ men of known quality, which is employed as a stand¬ ard. To do this with the degree of exactness neces¬ sary, sticks of very pure gypsum or plaster-of-Paris are cast of precisely the same dimensions, and then saturated with solutions of different glues, and thoroughly dried. They are placed one by one in a metallic ring having notches, which receive them, and a lever, having the centre of the stick as the resistance, and a graduated mercury cup upon the long arm as the counterpoise. A certain quantity of mercury having been poured into the cup until the stick employed as a standard commences to break, we may take this as the absolute standard, which may be marked 0, and the scale may then be numbered at equal distances above and below. For a glue less tenacious than the 4* 42 MANUFACTURE OF GLUE. standard, of course a less amount of mercury would be required, and making so many degrees below zero , but if a stick saturated with a stronger glue be placed in the apparatus, the mercury would stand above zero . The scale might be so graduated as to indicate for every degree of change a glue one per cent, stronger or weaker than the standard. II. RAW MATERIALS AND MANNER OF PREPARING THEM FOR THE MANUFACTURE OF GLUE. The raw materials used for the manufacture of glue consist of a variety of animal offal. The principal substances employed are refuse from the tanyard, such as scraps of ox and other thick hides, the debris of the workshops of leather-dressers, morocco leather manufacturers, etc. The tendons and intestines of many animals, rabbit and hare skins, deprived of their fur, cat and dog skins, scraps of parchment, surons, waste of turners and button makers, and offal from butcher shops and households, help to swell the series of materials used for the manufacture of glue. The materials are collected and sold either directly to the glue-boiler, or to dealers making a specialty of glue stock. Asa thorough knowledge of these waste products RAW MATERIALS. 43 is of great importance to the manufacturer, we shall devote this chapter to their discussion. 1.—Animal Skin. Strictly speaking, the skin of animals is composed of two parts, the corium or cutis and the cuticle or epidermis. The latter consists of separate and dis¬ tinct cells, and constitutes the exterior covering in which the wool, fur, or hair of the animal is rooted. It is of no importance to the glue manufacturer. The corium or cutis is the portion which furnishes the material for glue. Deprived of the epidermis, it is a substance organized of a number of fibres ramifying and intersecting one another in every direction, leaving, however, interstices contracting in size as they reach the outer portion, and which are more or less charged with fluid matter that serves to renew the cuticle and keep the skin pliant and moist. Beneath the corium lies a cellular tissue consisting of fat cells. When it is contaminated, as is frequently the case, with shreds of fat and flesh, it exerts a disturbing influence upon the manufacture of glue. The tanner trims the skins before steeping them in the ooze. From sheep and calf skins he removes the head portions, it being more advantageous to use them for glue stock. He also cuts off the skin covering the lower part of the thighs, and, to give the skin a neat finish, the ragged edges of the belly part. Of bullock 44 MANUFACTURE OF GLUE. hides the ears, tails, and foot pieces are utilized for glue stock, while the head parts are tanned. The refuse of tanning works and scraps of parch¬ ment are highly valued as glue stock, since they are in a fit condition for boiling without further preparation. Of still greater value are the so-called calves’ heads, which, after liming and drying, form a special article of commerce. Skins of hogs, hares, and rabbits yield a light-col¬ ored glue of little consistency. It is, therefore, best to use these last-named raw materials for the prepara¬ tion of glue-water, such as is used in sizing, in the manufacture of paper, etc. The older the animals from which the skins have been derived, the more solid the glue will be. In many cases, especially where a certain quality of glue is to he produced, it may be recommended to separate the different kinds of skin refuse into lots, provided there is enough of each kind to boil it separately. To prevent putrefaction, which is always accom¬ panied by decomposition of glue-yielding substance and consequent loss, the scraps must be carefully pre¬ served, especially in summer. The tanner prepares the refuse by macerating it during fifteen to twenty days in milk of lime, which is frequently renewed. By the action of the lime, adher¬ ing particles of blood and flesh are dissolved, and the fatty matter is saponified. After taking the scraps from the lime bath they are spread in the open air to drain and dry. This desiccation is accelerated by RAW MATERIALS. 45 turning them over with a fork several times a day. When sufficiently dry, the materials are packed up and sent to the glue factory. In case this work is not done carefully in the tan- yard, as is only too frequently the case, the stock is of hut little value to the manufacturer. By allowing the refuse to lie too long in a heap, as is sometimes done, a putrid fermentation sets in, the injurious effects of which cannot be remedied by sub¬ sequent liming, or the lime bath has not been strong enough, or has not acted sufficiently long upon the scraps to destroy the adhering particles of blood and flesh. The lime bath, on the other hand, may have been too strong, so as to attack the glue-yielding sub¬ stance. Frequently it is also the case that the scraps having been dried under unfavorable circumstances, mould has commenced to form, and finally they may be spoiled in winter by allowing them to freeze. Frozen glue leather yields glue of very little consistency. It will be seen from the foregoing that great pre¬ caution and care are required wffien buying glue- leather. The manufacturer should especially see that it is dry and tough, free from mould and all organic and inorganic substances, and not too strongly limed. The glue-boiler should, in all cases, be prepared to undertake the preparation of the glue stock himself. The following arrangements are required for the pur¬ pose. We assume that the glue factory is located on a stream of water. In the immediate neighborhood of 46 MANUFACTURE OF GLUE. the stream a sufficient number of pits to prepare all the glue stock used, each 2 metres (6.56 feet) deep, and 2 to 3 metres (6.56 to 9.84 feet) in diameter, and lined with cement, are so arranged that their bot¬ toms are about 1 metre (3.28 feet) above the level of the water. They are supplied with water by means of a conduit connecting them with each other. Each pit is provided with a discharge pipe for drawing off the dirty water. As the glue stock, before undergoing other opera¬ tions, has to be freed from the lime, it is packed in large strong willow baskets, and the latter submerged in the water by means of a travelling crane or other contrivance erected on the bank of the stream. The object is still better accomplished and in a shorter time, by the use of large wash-drums driven by the water itself, such, for instance, as are employed in tanneries for washing hides. They should be so con¬ structed as to allow of their easy filling or emptying without loss or waste. A good plan is to have them rest upon a frame with two wheels, by means of which they can be pushed into the stream after having been filled with 100 to 200 kilogrammes (220 to 440 pounds) of glue stock. One workman, assisted by the water, attends to the revolving of each drum. After washing, the drum is pushed to the drying ground and readily emptied by turning the part with the trap¬ door downward. The drying ground should, if possi¬ ble, be in the immediate neighborhood of the pits and in a sunny and airy location, and provided with an in- RAW MATERIALS. 47 dined floor of planks or cement, so arranged as to allow of the admittance of air from beneath. The glue-stock washer shown in figures 1, 2, 3, and 4 is the invention of Mr. W. A. Hoeveler (American patent), and it relates to the construction of appa¬ ratus for washing glue-stock. In apparatus for this purpose the stock is very commonly damaged by being broken up too much, and considerable loss results, besides, from the fact that the small particles are allowed to escape with the wash-water. By the present construction and arrange¬ ment these defects are remedied and other advantages derived. Fig. 1. Fig. 1 is a transverse vertical section on line x-x of Fig. 2 of this apparatus ; 48 MANUFACTURE OF GLUE. Fig. 2 is a longitudinal vertical section of the same ; Fig. 3 is an enlarged plan illustrating the screen and hinged covers, one being open and one closed ; and Fig. 2. Fig. 4 is a detail of the hub, stems, and part of one paddle. RAW MATERIALS. 49 Fig. 4. The apparatus is constructed in the form of a rect¬ angular trough-like structure, with its sides and ends, A, substantially water-tight by means of the double walls, a a. The upper portion of the interior is occu¬ pied by the swinging wash-box, B, semicircular in shape, with flat sides and rounded bottom throughout, the bottom being perforated. Upon a transverse shaft, N ATSON.—The Modern Practice of American Machinists and Engineers : Including the Construction, Application, and Use of Drills, Lathe Tools, Cutters for Boring Cylinders, and Hollow-work generally , with the most Economical Speed for the same ; the Results verified by Actual Practice at the Lathe, the Vise, and on the Floor. Together HENRY CAREY BAIRD & CO.’S CATALOGUE. 29 with Workshop Management, Economy of Manufacture, the Steam- Engine, Boilers, Gears, Belting, etc., etc. By Egbert P. Watson. Illustrated by eighty-six engravings. l2mo. . . . $2.