THE GETTY C E N 1 E K E 1 iH< A R Y APPLIED CHEMISTRY; MANUFACTURES, ARTS, AND DOMESTIC ECONOMY. EDITED BY * EDWARD ANDREW PARNELL, AUTHOR OF "ELEMENTS OF CHEMICAL ANALYSIS," LATE ASSISTANT CHEMICAL LECTURKR IN THE MEDICAL SCHOOL OF ST. THOMAS'S HOSPITAL, ETC. I. PRELIMINARY OBSERVATIONS. II. GAS ILLUMINATION. III. PRESERVATION OF WOOD. IV. DYEING AND CALICO-PRINTING. TP le^f Hi NEW YORK: • D. APPLETON & CO., 200 BROADWAY. PHILADELPHIA: GEORGE S. APPLETON, 148 CHESNUT ST. MDCCCXLIV. THE GETTY CENTEKy LIBRARY PREFACE. The " Preliminary Observations," with whicli this volume commences, comprise some brief considerations on the fundamental doctrines of chem- istry, most of which may be included in an account of the general laws which govern, and the phenomena and changes which accompany, the chemical combination of different bodies. This introduction concludes with an explanation of Chemical Symbols, and a table of Equivalents. The article on Gas Illumination comprises not only a detailed account of the process of making light-gas from coal, and of the chemical and physical properties of the constituents of coal-gas, but several important collateral subjects ; among which are some considerations on the modes of bimiing gas and on the economy of gas illumination, descriptions of the process for making light-gas from other sources than coal, and an account of the applications which the secondary products of the coal-gas manufacture have received. The construction of different kinds of regu- lators and meters, and the process of " naphthalizing" gas, are also con- sidered. In the article on the Preservation of Wood, which follows that on Gas Illumination, means are pointed out for effectually guarding against the ordinary decomposing influences of air and water on timber. A consid- erable portion of the article is devoted to an account of the important ex- periments of Mr. W. Hyett, on the effects of the impregnation of wood with foreign substances. Dyeing and Calico-printing forms the comprehensive subject of the concluding article of the present volmne. Most of the leading processes now practised by the calico-printers of this country are there described, accompanied with explanations of the scientific principles on which they are based. Several of these processes, new to treatises on the subject, will be found of considerable value. iv PREFACE. In many parts of the article on Calico-printing, I have derived material assistance from my esteemed friend Mr. Mercer, of the Oakenshaw print- works, near Blackbm-n, to whom I feel myself boimd to return my sin- cere thanks. I am also desirous of expressing my obligations to Mr. John Graham of the Mayfield print-works, Manchester; and to Mr. James Hindle of the Sabden works, near Whalley. TABLE OF CONTENTS. PAGE. Preliminary Observations • • 1 Attainments of the ancients in some chemical arts.— Probably acquired by chance. —Processes mostly devised and improved now by deductions from principles.— Theoretical principles may be erroneous, and the processes successful.— A few- valuable processes discovered accidentally in modern times.— Amalgamation pro- cess of Hernando Velasquez ^ Chemical affinity • / ' " j ' a Elements.— Difference between a chemical compound and a mechanical compouna. 4 Chemical affinity exerted with diflferent degrees of force between different substan- ^ Chemical" union of substances takes place in fixed and definite proportions.— The same element combines with difi'erent quantities of diflferent substances.— Table of chemical equivalents of elements.— Bodies always unite chemically m the pro- portion of their equivalents ^ Heat developed through chemical combination i V 'Vi' Chemical combination may be direct or indirect.— Double decomposition and double combination. — Single decomposition and single substitution 9 Solution.— Crystallization • V: Proximate and ultimate constituents Symbols J* Table of equivalents of acids and bases 1* I.— GAS ILLUMINATION. Outline of the process of making light-gas }^ § I.— Historical Sketch of the Progress of Gas Illumination lo § II. — Composition of Coal 19 .rvmnnoifmn A tnmip pfinstitntion of SDunt and can- 19 General composition.— Ultimate composition.— Atomic constitution of splint and can- nel coal. — Extraneous matters . § III. — Hydrocarbons ; ^1 Illuminating power of coal-gas due to hydrocarbons.— Isomerism 31 Light carburetted hydrogen. — Its composition and properties 22 Olefiant gas.— Mode of preparation.— Its properties and composition.— Fire-damp.— • Safety-lamp • *~ Naphthalin and paranaphthalin. — Coal-oil • ** § rV". — EProcess of making Coal-Gas 25 Coal-gas apparatus , *^ Figure exhibiting the arrangements of a gas-work *2 Table of the products of the destructive distillation of coal 27 Retort. — Mouth-piece. — Hydraulic main ■ ~° Gas carbon. — Method of removing it *2 Tar cistern.— Cooler or condenser.- Coolers of Mr. Perks and Mr. Malam ^ Lime purifier. — Wet-lime and dry-lime purifiers ^ Gasometer. — Telescope gasometer : •. • * Coal aflbrds diflferent products at different stages of the distillation.— Composition of coal-gas in one hundred volumes *. *i j Rules for producing good coal-gas.— Rotary retort.- Temperature of retort should not be above bright redness.— Advantage of selecting a rich coal.— Advantage of using coal with a minimum of sulphur, and previously dried 34 VI CONTENTS. . „ , ■ . PAGE. Ammonia formerly contained in purified coal-gas.— Process of Mr. Phillips, of Exe- ter, for removing the ammonia.— Use of copperas, dilute sulphuric acid, chloride of calcium, sulphate of manganese, and sulphate of lead, for removing the ammo- nia 37 § V. — Secondaky Products of the Coal-Gas Manufacture 33 Ammoniacal liquor [ * gg Coal-tar. — Coal-oil.— Coal-naphtha. — Pitch .*.'.*.'.'.'.'!!.'.'!!*. 39 Coke.— Composition and properties of coke. — Uses in metallurgic works, &c'. '. '. '. '. '. 39 § VI.— Oil-Gas. 40 Blind of oil used. — Process. — Apparatus.— Composition of oil-gas. — Liquids obtain- ed by the compression of oil-gas. — Benzin. — Oil-gas too expensive to be adopted in this country , § VII.— Resin-Gas 42 Resin-gas not adapted for this country. — Apparatus for making resin-gas. — Applica- tion of the volatile oil disengaged from the resin. — Product of gas. — Illuminating power of resin-gas 42 Turf-gas 43 § Vni. — Mode of burning Gas ; 43 Ignition. — Structure of an ordinary flame.— Luminous flame always contains solid matter heated to whiteness. — Luminosity of a flame depends on the consecutive combustion of the hydrogen and carbon. — Diflferent kinds of gas-burners. Cock- spur.— Union jet or fan.— Bat-wing — Fish-tail or swallow-tail.— Argand. — Bude light. — Solar gas-lamp 43 A given quantity of gas gives more light in one flame than in several flames. . . . . . 46 Influence of the shape of the chimney on the amount of light 46 Disadvantages of too free a supply of air . 47 Arrangement for burning gas as a source of heat in the laboratory . 47 Ventilation of gas-lights ' [ 4g § IX. — ^Economy OF Gas Illumination 49 Expenses of the manufacture, and the value of the products, in London . 49 Light from gas compared with that from other sources 50 Table showing the relative value of coal-gas made at difi'erent works '..* 51 Relative economy of coal-gas and oil-gas ^ 52 § X. — Estimation of the Value of Light-Gas , 52 Photometrical processes of Lambert, Dr. Ritchie, and M. Arago ..'.'!!!! 52 Illuminating power of light-gas related to the density 64 Illuminating power related to the quantity of oxygen required for the perfect com- bustion of the gas 55 Eudiometrical process , \\' 55 Process for the complete analysis of coal-gas 57 Simple process for estimating the value of light-gas by means of chlorine 58 § XI. — Regulators and Meters 68 Water and mercurial regulators.— Constant-pressure regulator.— Platow's gas mod- erator 58 Common water meter. — Edge's "improved gas meter" (note). — Clegg's "dry gas meter." — Lowe's meter. — Station meter ; 69 Naphthalized gas Apparatus used for « naphthalizing" gas.— Economical advantages of naphthalized gas ; 62 Attempt to convert tar into gas 62 n.— PRESERVATION OF WOOD. Rot and decay of wood are chemical changes. — Two conditions in which decay of wood can take place.— Nature of dry-rot 63 § I. — ^Pboperties and Composition of Wood G4 CONTENTS. vii PAGE. Woody tissue.— Cellular tissue— Structure of the first year's stem of an exogen.— Manner of growth of exogens.— Medullary rays.— Duramen or heart-wood. — ^Al- burnum or sap-wood. — Origin of woody tissue. — Endogens 64 Seasoning of wood Density of different kinds of wood 67 Soluble matters in wood.— Vegetable albumen. — Starch • • • 68 Preparation and properties of pure lignin.— Dextrin.— Starch Sugar.— Composition of oak-wood and beech-wood.— Researches of M. Payen on wood.— Cellulose. — Products of the destructive distillation of wood.— Flame of burning wood.— Wood smoke.— Heating power of different kinds of wood in a state of combustion. — Composition of wood ashes 68 § II. — ^Nature and Causes of the Decay of Wood 73 Decay of woody |B|re a process of oxidation. — ^Eremecausis • • • 73 Decay of wood always produced by the contact of another body undergoing a simi- lar change 15 Decay of wood closely analogous to acetification '5 Albuminous matter in wood acts as a ferment 76 Processes for ascertaining the proportion of albuminous matter in wood 76 § ni. — Preservative Materials 76 Decay of wood may be prevented by removing the albumen, or by preventing its de- composition ' 76 Removal of the albumen by water 76 Corrosive sublimate - 77 Action of corrosive sublimate confined to the albumen 77 Process for applying corrosive sublimate 77 Protection of wood by the application of a varnish 78 List of preservative materials 78 Sulphate of copper, sulphate of iron, and sulphate of zinc 78 Alkalies and alkaline earths 78 Alum 79 Common salt 79 Vegetable and animal oils 79 Vapor from fixed oils 79 Arsenious acid. — Mundic water 79 Tannin. — Durability of wood imbedded in bogs 80 CJreosote • 80 Tar 80 Oil of wood-tar • 80 Peroxide of tin ; perchloride of tin. — Oxide of copper ; nitrate of copper; chloride of copper 81 Solution of bitumen in oil of turpentine 81 Yellow chromate of potash ; bichromate of potash. — Solution of caoutchouc. — Lime- water of gas-works. — Beeswax and turpentine. — Drj'ing oil and turpentine 81 Chloride of zinc (SirW. Burnett's patent) 81 Iron liquor 82 Bojicherie's experiments to determine the relative amount of protection from decay afforded by corrosive sublimate, sulphate of iron, iron liquor, and arsenious acid. 82 § IV. — Modes of applying Preservative Agents 82 Application of the aspirative force of the tree suggested by Dr. Boucherie. — Process of impregnating wood with a liquid by aspiration. — Different liquids are une- qually absorbed. — A more advantageous mode of impregnation. — The most porous woods are not those most easily penetrated. — Process for impregnating seasoned timber. — Apparatus used at the Portsmouth dock-yard for injecting into wood a solution of chloride of zinc 83 § V. — Other Effects of the Impregnation of Wood with Foreign Sot- stances 85 The hardness of the wood increased 85 The flexibility and elasticity of wood preserved • • 85 Experiments of Mr. Hyett on the deflection of larch and beech impregnated with different substances 85 viii CONTENTS. Strength of the wood may be increased or diminished gj Resinous and non-resinous trees require different treatment .* 87 Inflammability and combustibility of wood reduced by impregnation with foreign sub- stances Tendency to warp diminished .'.'.'.".*.' 88 Application of colors to wood by the aspirative process 88 Density of wood increased by foreign substances 89 Tables showing the specific gravity of prepared larch and beech .'.'*.' 89 Table embodying the principal results of Mr. Hyett's experiments on the best ma- terials for preserving wood 9q III.— DYEING AND CALICO-PRINTING. Dyeing a chemical art. — Object of dyeing Hl^ 92 § I. — History of Dyeing and Calico-Printing 92 Dyeing practised from time immemorial in the East. — Tyre celebrated for its dyers. — Tyrian purple. — Dyers of ancient Greece and Rome 92 Progress of dyeing in Europe affected by the invasion of the Northern barbarians in the 5th century.— The art did not revive until the 12th or 13th century .—Flor- entine dyers 93 Progress of the art affected by the discovery of America.— Application of a salt of tin. — ^Use <5f logwood and indigo prohibited. — Madder introduced.— Application of mineral colors. — Turkey red 93 Proficiency of the ancients in topical dyeing.— Variegated linen cloths of Sidon.— Derivation of the term calico-printing. — Pliny's account of the Egyptian process of topical dyeing. — Pallampoors.— Topical dyeing in Mexico 94 Progress of calico-printing in Europe — Printed cottons and linens of Augsburg.— First print-ground in England.— Calico-printing favored by the prohibition of the importation of chintzes. — Duty imposed on printed calicos. — Wearing of all print- ed calicos prohibited in 1720.— A mixed fabric of linen and cotton was allowed to be printed in 1730, and the uniform cotton fabric in 1774.— Duty of three- pence-halfpenny per square yard repealed in 1831 94 Mechanical improvements in calico-printing.— A copper-plate the first improvement on the wooden hand printing block. — Invention of cylinder or roller printing. Capabilities of cylinder printing.— Surface printing.— Mule machine.— Press ma- chine 95 Chemists who investigated the principles of dyeing during the last century.— Appli. cation of chlorine for bleaching.— Introduction of mineral colors.—Antimony, or- ange, and manganese bronze first introduced by Mr. Mercer, and the two chro- mates of lead by M. Kcechlin gg § II. — General Properties of Vegetable Coloring Matters 96 Only a few have been isolated in a pure state.— General composition.— Action of humid air. — Action of acids and alkalies. — Many organic coloring matters are feeble acids.— Lakes.— The attraction of coloring matters for insoluble bases is chemical affinity, and not a mere surface attraction 96 Action of chlorine, chromic acid, and sulphurous acid, on organic coloring matters'. —Animal charcoal.— Several coloring matters are oxides of colorless radicals.— Deoxidizing agents.— Other coloring matters form colorless hydrurets 98 Coloring matters attach themselves to tissues.— Divisions of coloring matters into two classes.— Mode of applying members of each class to tissues 99 Nature of color 2qq List of vegetable and animal coloring matters *.*.*.!'.!'.!*.!'. 101 Alkanet !.'!!.*.'."!.'.',".*." 101 Annatto !.'.'.'!!.*!!!!!!..' 101 Archil, litmus, turnsole, cudbear i .'!'.!!!!'..'!'.!.*!'.'. .* id Barwood, camwood .'!!!.*!!!.*!!.*.*.'.' 102 Brazil-wood, sapan-woo^ Fernambouc wood, peach-wood, Nicaragua-wood .' 102 Catechu, or tena Japonictt * Cochineal ; coccinellin .'.'.*.'.*!.'.*.'.*.'.*..* 102 French berries ; Avignon berries ; Persian berries !!!!*.*.!!!". 102 Fustet, or yellow fustic .'!!.'.'!.'.".*!.*!.'" 102 Fustic, or old fustic .'.*.*."!!.'.'!! '. " 102 CONTENTS. a PAGE. Indigo; indigotin 103 Kermes grains 103 Lac-dye; stick-lac 103 Logwood 103 Madder 103 Quercitron 103 Saflflower 103 Sandal-wood (red Sanders-wood) 104 Sumach, galls, valonia, and saw-wort .' 104 Turmeric 104 Weld 104 Woad 104 List of mineral colors employed in dyeing 104 Antimony orange 104 Arseniate of chromium 104 Chrome-yellow 104 Chrome-orange 104 Manganese brown 104 Orpiment , 104 Peroxide of iron (iron huff) 105 Prussiate of copper 105 Prussian blue 105 Scheele's green (arsenite of copper) 105 § in. — General Natuke of Dyeing Processes 105 Processes for different kinds of fabrics dissimilar 105 Singeing of cottons by furnace 105 Singeing by gas 106 List of operations practised in bleaching cottons 106 Bleaching of mousselin de laines 106 Preparation of silk for printing 107 Coloring matters must be applied in solution 107 Arrangement of all dyeing processes under four heads 107 Nature of the processes for applying mineral colors 107 Modes of applying coloring matters which are soluble in water 108 Mordants 108 The mordant should exist on the cloth about to be dyed in an insoluble form 109 An insoluble subsalt is often produced through the desiccation of the mordant on the doth 109 Cases in which the desiccation of the mordant may be omitted 110 Reasons for removing all excess of mordant 110 Alterant 110 Dyeing from a mixed solution of coloring matter and mordant Ill Different colors of the compounds of the ^ame coloring matter with different mor- dants Ill Mordants in common use 112 Alumina 112 Alum 112 Basic alum 113 Red liquor and acetate of alumina. — Preparation of red liquor. — Composition of common red liquor. — Decomposition of red liquor by heat. — ^Acetate of alumina 113 Aluminate of potash 116 Tin mordants. — Peroxide of tin. — Perchloride. — Mixture of perchloride and perni- trate. — Pink salt. — Stannate of potash 116 Protoxide of tin. — Salts of tin. — Plum spirits 117 Iron mordants. — Acetate of iron. — Iron liquor. — Peroxide of iron. — Pernitrate. — Sub-pernitrate. — Basic persulphate 118 Assistant mordant 119 Brightening action of dilute acids on the teints of compound of coloring matters and mordants. — Acids may act by preventing the attachment of an excess of coloring matter. — Disintegration of the mordant the principal effect of the acid. — Acids may unite permanently with the compound of coloring matter and mor- dant 119 X CONTENTS. PAGE. Dunging. — Object of dunging. — Process. — Composition of cow-dung. — ^Action of the dung 122 Dung substitute. — Mode of preparation.— Cleansing liquor. — Mode of applying dung substitute 124 Branning 126 Preparation of dyeing infusions 126 Dyeing. — Dye-beck 126 Modes of dyeing with insoluble coloring matters 127 Mode of imparting a color by partially corroding the fibre 127 Temperature of the dye-beck 127 Finishing operations on calico printed and dyed with madder colors. — Dash-wheel. — Rinsing machine.— Clearing. — Water extractor. — Starching machine. — Steam drying machine. — Calendering 128 Purity of the water employed in dyeing 132 § IV. — Calico-Pkinting Processes 133 Characteristics of the six different styles of printing processes 133 Block-printing. — Rainbow style 134 Stereotype printing plate 135 Perrotine • 135 Cylinder printing 135 Modes of engraving copper rollers 136 Press printing 137 Surface printing ; • • 138 Thickeners • • . 138 Madder style.— Printing.— Drying.— Ageing.— Dunging.— Dyeing.— Clearing 140 Madder purple of two shades 143 Madder red of two shades 143 Madder reds and purples combined 145 Other coloring matters applied in the madder style. — Quercitron. — Madder and quercitron. — Logwood. — Cochineal 144 Topical and steam colors.— Topical black. — Catechu brown. — Spirit purple. — Spirit chocolate.— Spirit pink.— Spirit yellow.— Topical blues 144 Steam colors. — Previous preparation of the cloth 148 Steam black. — Steam red.— Steam purple.— Steam yellow and orange. — Steam blue. — Steam green 148 Process of steaming • • 152 Design in steam colors entirely 153 Design in madder colors and steam colors combined 153 Modes of applying mineral coloring matters as grounds and as figures 153 Padding machine 154 Prussian blue. — Chrome-yellow. — Chrome-orange. — Iron bufi". — Manganese bronze. — Scheele's green 154 Example of the combination of mineral colors with madder and steam colors 156 Resist style 157 Fat resists ; 157 Resists for mordants. — Acid resists. — Protochloride of tin as a resist for iron liquor. — Citrate of soda as a resist for iron liquor and red liquor 157 Resists for the coloring matter. — Chiefly adapted to indigo.— Materials employed. — Course of operations. — Mode of action of salts of copper and mercury. — Ac- tion of sulphate of zinc. — Blue-vat. — Receipts for resist pastes 159 Process for obtaining figures in white and light blue on a dark blue ground. — Mode . of procuring figures in yellow or orange on a blue ground. — Figures in yellow and light blue on a dark blue ground. — Figure in buff on a blue ground. — Fig- ure in buff on a green ground 160 Lapis or neutral style. — Resist red. — Course of operations. — Resist black. — Pro- cess for obtaining figures in light blue and a madder color on a blue ground. — The same with a white figure. — Design in chrome-orange, white and crimson on a blue ground.— Chocolate ground neutral style 161 Resist for catechu brown 163 Principle of the discharge style 163 Dischargers for coloring matters 164 White discharge by chloride of lime and an acid 164 Dischargers for Turkey red and other madder colors .♦. . 164 CONTENTS. xi Imitation of Bandanna handkerchiefs. ^^?64 Colored designs on Turkey red ground.— Chrome yellow and Prussian blue oii red 165 Chromic acid discharge for indigo jg5 Combination of madder style with the preceding jgg Dischargers for mineral coloring matters. — For Prussian blue.— For manganese brown. — Colored designs on manganese ground. — Dischargers for chrome yel- low, chrome orange, and iron buff 266 Dischargers for mordants.— Course of operations practised in this style of work*. '. 167 Combination of the indigo resist style with the preceding ] 168 Combined mordant and discharger jgg China blue style 169 Printing of mousselin de laines, silks, chalis, &c 172 Manderining style 174 INDEX. Acetate of iron, see Iron liquor. of alumina, see Red liquor. Acids, action of, on compounds of coloring mat- ters and mordants, 119. Adrianople red, see Turkey red. Affinity, chemical, 3. Ageing of cottons printed with aluminate of pot- ash, m. printed with red liquor, 115. printed with iron liquor, 118. Albumen, compound of, with corrosive subli- mate, 77. muriate of, 77, note. vegetable, contained in wood, 68, 76. ^ vegetable, how removed from wood, 76. Albuminate of mercury, 77, note. Alburnum, 65. Alizarine, 103. Alkanet, 101. Alterants, 110. Alum, 112. basic, 113. proximate and ultimate constituents of, 11. test for the purity of, 112. use of, for preserving wood, 79. use of, in purifying coal-gas, 37. Alumina, acetate of, see Red liquor, how applied to cloth, 112. how prepared, 112, note, nitrate of, 116. subsulphate of, 112. tartrate of, 116. Aluminate of potash, 116. action of muriate of ammonia on, lib. effects of ageing cottons printed with, 116. of soda, 116. Aluminum, chloride of, 116. Ammonia in coal-gas, 37. , , , Ammoniacal liquor of gas-works, 15 ; composi- tion and uses of, 37. Annatto, 101. how applied to tissues, 100. when introduced into Europe, 93. Antimony orange, 96, 104. Apophylite, formula for, 13. Aqua-fortis, 7. Archil, 93, 101. Argand burner, 45. Arseniate of chromium, 104. Arsenious acid, use of, for preservmg wood, 79, 82. Aili from wood, 71, 72. Assistant mordant, 1190 Arsenite of copper, 105. Avignon berries, 102. Bandanna handkerchiefs, 164. Barwood, 102. Bases, 4. Basic alum, 113. Bat-wing burner, 45. , Bergmann, researches of, m dyeing, 96. Berthollet, introduction of chlorine by, 96. researches of, in dyeing, 96. Berries, Persian, French or Avignon, 102. Bichromate of potash, use of, for preserving wood, 81. , „, Bitumen, use of, for preservmg wood, 81. Black, steam, 148. resist, for the blue-vat, 162. topical, 107. Bleaching of cotton, 106. of mousseUn de lames, luo. Block, hand printii.g, 134. Blue, Prussian, 105. steam, ISO. topical, 147. Blue-vat, 159. Bone-size, 124. Boracic acid 5. Boucherie's mode of impregnating wood with a liquid, 83. Bran, use of, in clearing dyed goods, 126. Branning, 126. Brazil-wood, 93, 102. British gum, 138. Brown, resist for catechu, 163. , topical, 145. Bude liglit, 46, note. Burnett, patent of Sir William, for preservmg wood, &c., 81. Calendering, 131. CaUco-printing, derivation of the name of, 94. history of, 92. processes in, 133. progress of, in England, 95. Cambium, 64. Camwood, 102. Carbonate of lime, 5. Carburetted hydrogen, 22. Catechu, 102. resist for, 163. Cellulose, 69. Charcoal, animal, decolorizing power of, 98. Chemical affinity, 3, 5. combinations, definite nature of, 6 ; di- rect and indirect, 9. China blue style, 134, 169. China blue, mixture for, 164. order of dipping for, 168. China clay, use of, as a thickener, 139. Chloride of calcium, use of, in purifying coal-gas, 37. of copper, use of, for preserving wood, 78. of lime, use of, in clearing dyed goods, 1 30. of mercury, use of, in preserving wood, 77, 82. of zinc, use of, for preserving wood, 81. Chlorine, action of, on vegetable coloring mat- ters, 98. how applied in calico-printing as a dis- charger, 163, et seq. relative affinity of different metals for, 4. Chocolate, spirit, 146. ground neutral style, 163, 169, note. Chromates of potash, use of, for preserving wood, 81. Chrome-orange, 104, 154, 161. dischargers for, 167. Chrome-yellow, 104, 154, 161. dischargers for, 167. mode of applying a design in, to a Tur- key red ground, 165. Chromic acid, use of, for discharging indigo, 166. action of, on vegetable coloring mat- ters, 98. Chromium, arseniate of, 104. Cleansing liquor of print-works, 124. Clearing excess of coloring matter by bran, 130, 141. excess of coloring matter by chlonde of lime, 130, 141. excess of coloring matter by soap, 130, 142. Clegg's dry gas-meter, 60 INDEX. xiii Coal, composition of, how ascertained, 19. impurities in, 9. products of tlie destructive distillation of, 27, 34. secondary products of the distillation of, 38. value of tlie products of the distillation of, 49. Coal-gas retort, 28. Coal-gas, advantage of using dry coal in making, 36. ammonia in, 37. comparison of the illuminating power of, with that of oil-gas, 53. composition of, at different stages of the process, 33. cost of, compared with that of other sources of light, 50. density of, compared with its illumina- ting power, 55. disadvantages of too high a temperature in making, 35. how freed from ammonia, 37. lime purifier for, 30. mode of burning, as a source of heat, 47. modes of estimating value of, 52. outline of process for making, 15, 25. present consumption of, in London, 18. process for the complete analysis of, 57. process of making, 25, 34. product of, from different kinds of coal, 35. production of, at different gas-works, 52. state of the manufacture of, in London in 1823, and at the present time, 18. Coal-naphtha, composition and uses of, 39. Coal-oil, 39. Coal-tar, 15, 39, 62. Coccinellin, 102. Cochineal, 102. dyeing cottons with, 144. Cockspur name, 45. Coke, uses of, 39. Color doctor, 136. nature of, 100. Coloring matters, attachment of, to tissues, 99. dischargers for, 164. form compounds of different colors with different mordants. 111. general composition of vegetable, 96. general properties of vegetable, 96. how imparted to wood, 88. list of vegetable and animal, 101. mineral, how applied to cloth, 106. mostly derived from vegetables, 96. organic, division of, 99. organic, how applied to tissues, 99. resists for, 99. vegetable, action of chromic acid on, 98. vegetable, action of chlorine on, 98. vegetable, action of sulphurous acid on, 98. vegetable, colorless bases of, 98. vegetable, combinations of, with alumi- na, &c., 98. vegetable, unite chemically with bases, 97. Combining proportions, 5. Condenser for coal-gas, 29. Cooler for coal-gas, 29. Copper, arsenite of, 105. prussiate of, 105. use of chloride of, for preserving wood, 81. use of oxide of, for preserving wood, 81. use of salts of, for resisting indigo, 159. use of the sulphate of, for preserving wood, 78. Copperas, use of, in purifying coal-gas, 37. Corrosive sublimate, use of, in preserving wood, 77, 83, 87. Cotton, bleaching of, 106. e Cow-dung, composition of, 123. Creosote, use of, for preserving wood, 80. Cudbear, 102. Cylinder printing, 135. capabilities of, 95. Cylinder printing, invention of, 95. Cylinder-printing machine for pencil-blue, 147. Dash- wheel, 128. Davy lamp, 23. Decay of wood, 63 ; causes of the, 73. a process of oxidation, 73. Decoctions for dyeing, how made, 128. Decompositions, double, 9. De laines, bleaching of, 106. printing of, 172. Dextrin, 139 ; produced from lignin, 69. Discharge, chlorine, 164. Discharge of indigo by chromic acid, 165. style, 163. style, principle of, 134. Discharger and mordant combined, 169. for coloring matters, 164. for iron buff, 167. for manganese brown, white and col- ored, 166. for Prussian blue, 165. Dischargers for chrome-yellow and chrome-or- ange, 167. for mordants, 167. Doctor, color, and lint, 136. Drying machine, steam, 131. Dry gas meter, 60. Dry-lime purifier for coal-gas, 31. Dry-rot, 63. Dung, action of, in the dunging process, 124. composition of, from the cow, 123. Dung substitute, 125 ; how best applied to cloth, 125. Dunging process, how performed, 132. Dunging sometimes superseded by branning, 126, use of, in calico.printing and dyeing, 123 Duramen, 65. Dye-beck, 126. how heated, 126. Dyeing, history of, 92. materials used jsy Romans in, 92. objects of, 92. operation of, 127, 128. processes of, different for different kinds of tissues, 105. processes of, general nature of, 105, 107. purity of water used in, 132. Dyers' spirits, 118. Elements, 3. Endogens, structure of, 66. Epsom salts, or sulphate of magnesia, 11 Equivalents, chemical, 6, 7. tables of chemical, 7, 14. Etching of printing rollers, 136. Eudiometer, Ure's, 55. Eupion, 80. Exogenous trees, growth of, 64. structure of stem of, 64. Fancy colors, 146, note. Fat resists, 157. Felspar, 4, 13. Fernambouc wood, 102. Fibre, affinity of the animal and vegetable, foi coloring matters, 99. Fire-damp, 23. Fish-tail burner, 46. Flame, cause of the luminosity of, 44. structure of, 43. Flour, 138. French berries, 102. Furnace, singeing, 105. Fustet, 102. Fustic, 102. Galls, 104. Gas cooler, 29. flames, chimneys for, 46. illumination, 15 ; see Coal-gas. economy of, 49. history of the progress of, 15 lights, ventilation of, 48. xiv INDEX. Gas meters, 59. meter, Clegg's dry, 60. moderator, Platow's, 59. regulators, 58. Gas; mode of burning. 43. naphthalized, 51. Gas-works, arrangement of, 25, 26. Gasometer, 32 ; telescope gasometer, 32. Garancine, 103, 142. Glazing of cottons, 131. Granite, 4. Green, steam, 152. Gum arabic, 138. Senegal, 138. tragacanth, 138. Gum, British, 138. Gypsum in coal, 20. Humus from oak, composition of, 74. Hydraulic main, 15, 28. Hydriodic acid, composition of, 6. Hydrocarbons, 21. Hydrochloric acid, composition of, 6. Hydroferrocyanic acid, 152. Hyett, experiments of Mr. W. H., on the impreg- nation of wood, 84, 90. Ignition, 43. Indigo, 103. Indigo-vat, 159. Indigo, as a topical color, 147. how applied to tissues, 100. how discharged by chromic acid, 166. peculiar action of chlorine on, 98. use of, formerly prohibited, 93. resist style with, 160. when introduced into Europe, 93. Indigotin, 103. Iron buff, 105, 155, 161. discharger for, 167. liquor, how prepared, 118. resists for, 157, 159. use of, as a mordant, 118. use of, for preserving wood, 81, 88. mordants, 1 18. pyrites in coal, 21. Iron, acetate of, see Iron liquor, aceto-persulphate of, 119. pemitrate of, 119. peroxide of, 105. pyrolignite of, see Iron liquor. use of, for preserving wood, 81, 88. sub-pernitrate of, 119. sub-persulphate of, 119. test for the presence of, 113. Isomerism, 21. Kermes grains, 103. Kyan's process for protecting wood, 77. Lac dye, 103. Lakes, 97. Lamp, ventilating, 49, safety, 23. Lamp-black, composition of, 70, note. Lapis style, 161. Lazulite style, 161. Lead, chromate of, 104. use of sulphate of, in purifying coal-gas, 38. Light carburetted hydrogen, 22. Light, constitution of, 101. Light-gas, see Coal-gas, Gas illumination. density of, compared with the illumi- nating power, 55. process for the complete analysis of, 57. modes of estimating the value of, 53. Lignin, 68. Lignin-sulphuric acid, 69. Lime, aflSnity of, for tissues, 100, note. Lime, experiment on, as a preservative for wood, 78. Lime purifier for coal-gas, 30. Lint doctor, 136. Liquor, patent purple, 119. Liquor, iron, see Iron liquor. red, see Red liquor. Litmus, 103. Logwood, 103. dyeing cottons with, 145. when introduced into Europe, 93. use of, prohibited by Queen Elizabeth, 93. Lowe's naphthalized gas, 61. Macquer, M., researches of, in dyeing, 96. Madder, 103. colors, application of fat resist to, 157. combination of, with mineral and steam colors, 156. combination of, with steam colors, 153, 156. purples, 143. and reds conjoined, 143, 169. reds, 143. style of printing, principle of, 140. style of printing, processes in, 141,etseq. style, combination of, with the' discharge style, 16fi, 168. Madder, use of adding sumach to, 142, note. Mandarining style; 174. Manganese brown, 104, 156. white and colored dischargers for, 166. Manganese, use of sulphate and chloride of, in purifying coal-gas. 38. Matters, coloring, see Coloring matters. Medullary processes, 64. 65. Mercer, Mr., introduction of antimonv orange by, 98. introduction of manganese bronze bv. 98. Mercury, albuminate of, 77, note. Meters for gas, 58. Mica, 4. Mineral coloring matters, combination of, with madder and steam colors, 156. how commonly applied to cloth, 107. modes of applying, 154. Mordant, 108. Mordant and discharger combined, 169. assistant, 119. Mordants, aluminous, 113. dischargers for, 167. how applied, 109, 111. iron, 118. resists for, 157. tin, 116. Mouldered wood, composition of, 75. Mousselin de laines, bleaching of, 106. printing of, 173. " Mule" printing machine, 96. Murdoch, Mr,, introduction of coal-gas by, 17. Muriate of ammonia in coal, 20 Naphthalin, 24. Naphthalized gas, 61. Neutral style, 161. Nicaragua wood, 103. Nitrate of alumina, 116. Nitrates of iron, 119. Nitric oxide, 7. acid, 7. Nitrous acid, 7. oxide, 7. Oak-wood, composition of humus from, 74. Oil of wood-tar, preparation of, 80. use of, for preserving wood, 80. Oils, vegetable and animal, use of, for preserving wood, 79. Oil-gas, 40. apparatus for making, 40. comparison of the illuminating power of, with that of coal-gas, 53. liquids obtained by compression of, 41. properties and composition of, 41. defiant gas, 22. Orange, antimony, 96, 104. Orpiment, 104. mDEX. XV Oxide of copper, preservation of wood by, 81. Padding style, 134. Pallampoors, 94. Paranaphthalin, 24. Parrot coal, 21. Pastes, resist, for indigo, 160. Peach- wood. 103. Pencil blue, 147. Perchloride of tin, 117. Pernitrate of iron, 119. Peroxide of iron, 105. of nitrogen, 7. of tin, how applied to cloth, 1 16. preservation of wood by, 81. use of, as a mordant, 116. Perrotine, 135. Persian berries, 102. Phlogiston, theory of, 2. Photometer, Ritchie's, 54. Pink salt, 117. Pink, spirit, 146. Pipe-clay, use of, as a thickener, 139. Pitch, 39. Platow's gas moderator, 59. Plum spirits, 118. Potash, aluminate of 116. stannate of, 117. use of chromates of, for preserving wood, 81. Preservation of wood, 63. by alum, 79. , by arsenious acid, 79, 82. by bitumen, 81. by chloride of line, 81. by the chromates of potash, 8l. by common salt, 79. by corrosive sublimate, 77. , by creosote, 80. ' by iron liquor, 81, 88. i by oil of wood-tar, 80. by oxide of copper, 81. by peroxide of tin, 81. by a resinous coating, 78. by solution of creosote, 80. by sulphate and acetate of copper, 78. by sulphate of iron, 78, 82. by sulphate of zinc, 78. by tannin, 79, 80. by vegetable and animal oils, 79. by wood-tar, 80. Preservative materials for wood, 76. Preserving wood, Kyan's process for, 77. press printing, 137. Printing by roller, 135. invention of, 95. roller, how made, 136.- Protochloride of tin, 117 ; use of, as a resist for iron liquor, 158. Protosulphate of iron, use of, in purifying coal- gas, 37. Protoxide of tin, use of, as a mordant, 117. Pro.ximate constituents, 11. Prussian blue, 105, 151, 154. as a topical color, 147. , how discharged by an alkali, 166. how applied to wood, 88. how applied as a steam-color, 150. mode of applying a design in, to a Tur- key red ground, 165. Prussiate of copper, 105. Purple liquor, patent, 119. Purple, madder, 143. spirit, 146. steam, 149. Tyrian, durability of, 92. Pyrolignite of iron, see Iron liquor. Quartz, 4. Quercitron, 103. dyeing cottons with, 144. Rainbow style, mode of printing for the, 135. Rays of light, colored, 100. Red liquor, altered by heat, 115. Red liquor, constitution of, 114. effects of ageing on cottons printed with, 114. preparation of, 113. resist for, 158. Red resist for the blue-vat, 162. Sanders wood, 104. spiiits of dyers, 118. Red, steam, 149. Resin, covering of, for wood, 78. products of the distillation of, 42. Resin-gas, 42. apparatus for making, 42. Resist black for the blue-vat, 162. pastes for indigo, 160. purple and chocolate, for the blue-vat, 163. red, for the blue- vat, 161. for catechu brown, 163. style, principle of the, 134. processes in the, 157. Resists for coloring matters, 159. for indigo, 159. for mordants, 157. Resists, adaptation of, to the madder style of work, 157, 158. fat, 157. Retort, Clegg's rotary, 34. coal-gas, 28 Regenerator, Malam's gas, 62. Regulators, 5S. Rinsing machine, 129. Ritchie's photometer, 54. Roller printing, 135. capabilities of, 95. invention of, 95. Rotary retort, 34. Royal blue, 173. Safety lamp, 23, Safflower, 103. how applied to tissues, 100. Sago starch, 138. Salop, 138. Salt, common, in coal, 20. use of, for preserving wood, 79. composition of, 9, 11. general meaning of the term, 4. Salts of tin, 118. Sandal -wood, 104. Sapan-wood, 102. «aw-wort, 104. Scneele's green, 105, 156. Seasoning of wood, Langton's mode of, Sightening of mordants, 140. Silk, how prepared for printing, 107. printing of, 173. Singeing, 105. Soap, use of, in clearing dyed goods, 130. Soda, aluminate of, 116. citrate of, use of, as a resist, 157. Solution, 10. Soot, composition of, from wood, 70, note. Spirit chocolate, 146. colors, 146, note. pink, 146. purple, 146. yellow, 146. Spirits, dyers', 118. Spurious coal, 21. Squeezing-rollers, 130. Stannate of potash, 1 17 ; application of, to cot- ton for steam colors, 148. Starch contained in wood, 68. sugar, 69. Starch, wheat, 138. Starching machine, 131. Station meter, 61. Stearn black, 148. blue, 150. for woollen goods, 173. colors, 148, 153. for woollen goods, 173. combination of, with madder colors, 153, 157. xvi INDEX. Steam colors, combination of, with madder and mineral colors, 156. adaptation of, to resist style and madder style, 157. preparation of cotton for receiving, 148. Steam drying machine, 131. green, 162. printing, principle of, 134. purple, 149. red, 149. Steam scarlet for woollen goods, 173. yellow, 149. Steaming process, 152. Stereotype printing-plate, 135. Stick-lac, 103. Substitute liquor, 125. Substitute dung, 124. Substitutions, double and single, 9, 10. Sulphate of copper, use of, for preserving wood, 78. use of, for resisting indigo, 159. Sulphate of iron, use of, for preserving wood, 78, 82. of lead, use of, as a thickener, 139. use of, in purifying coal-gas, 38. of magnesia, 11, 12. of zinc, use of, for preserving wood, 78. Sulphuretted hydrogen, composition of, 6. Sulphuric acid, use of, in purifying coai-gas, 48. relative affinity of different bases for, 4. Sulphurous acid, action of, on vegetable coloring matters, 98. Sumach, 104. Surface printing, 138. Swallow-tail burner, 45. Symbols, 12 ; table of, for elements, 12. Tannin, use of, for preserving wood, 79, 80. Telescope gasometer, 32. Temperature, change of, a result of chemical action, 8. Terra Japonica, 102. Thickeners used in calico-printing, 138. Tin mordants, 116. Tin, peroxide of, use of, as a mordant, 116. protoxide of, use of, as a mordant, 117. use of perchloride of, for preserving wood, 81. use of protochloride of, as a resist for iron liquor, 158. Tissues, affinity of lime for, 100, note. Topical and steam colors, 144. black, 107. blue, 147. brown, 145. style of printing, principle of, 134. Tragacanth, gum, 138. Turf-gas, 43. Turkey red, history of, 93. mode of applying a design in Prussian blue to a ground of, 165. mode of producing a chrome-yellow de- sign on a ground of, 165. white discharge for, 164. Turmeric, 104. Turnsole, 104. Tyrian purple, durabiUty of, 92. Ultimate constituents, II. Union-jet flame, 45. " Union" printing machine, 96. Ure's eudiometer, 55. Valonia, 104. Vegetable albumen, 68. how removed from wood, 76. how to ascertain proportion of, in wood. 76. r r , , Vegeto-sulphuric acid, 69. Wash-off colors, 145. Water, composition of, 6. Water extracter, 130. used in dyeing, 131. Weld, 104. Wheat starch, 138. Winsor, Mr., introduction of coal-gas into the metropolis by, 17. Woad, 104. Wood, amount of water in, 66. ash, 72. Boucherie's mode of impregnating, with a liquid, 83. composition of mouldered, 75. decay of, 63, 73, 75. density of, 67, 89. effects of the impregnation of, with for- eign substances, 85. how freed from albumen, 76. how to apply colors to, 88. how to ascertain proportion of vegetable albumen in, 76. how to increase or diminish strength of, 87. how to preserve flexibility and elasticity of, 85. how to reduce the inflammability and combustibility of, 87. Kyan's process for preserving, 77. necessary condition for the decay of, 75. preservation of, 63, see Preservation of wood. preservative materials for, 76, 78. products of distillation of, 70. properties and composition of, 64. starch contained in, 68. smoke from, 70. tar of, products of distillation of, 80. tar, use of, for preserving wood, 80. Woody fibre, composition of, 75. tissue, function of, 64. origin of, 65, note, structure of, 64. Woollen goods, printing of, 172. steam colors for, 173. Yellow fustic, 102. lake, 97. Yellow, steam, 149. spirit, 146. Zinc, use of chloride of, for preserving wood, 81. Zinc, use of sulphate of, for preserving wood, 78 ; for resisting indigo, 160. APPLIED CHEMISTRY, IN MANUFACTURES, ARTS, AND DOMESTIC ECONOMY. PRELIMINARY OBSERVATIONS. Really valuable improvements of old and inventions of new processes in the chemical arts and manufactures are not often the result of chance, in the present advanced state of chemistry, but of a logical application of recognised chemical principles of greater or less generality. Such has been the case since the existence of chemistry as a distinct science possessed of general laws. The surprising attainments of the ancients in certain chemical arts would lead us to infer that processes may be invented, and even successfully applied, without the smallest conception of the principles on which they depend. The ancient Egyptians and Phoenicians were not only acquainted with the means of extracting iron, copper, gold, silver, lead, and tin, from the ores containing these metals, but with complicated processes for the preparation of several metallic compounds. They extracted soda from the soil in which that alkali naturally exists, and understood the means of purifying it ; they procured pot- ash from the ashes of plants, and made soap by combining the alkalies with oils and fats. They were acquainted with the mode of converting an alkaline carbonate into a caustic alkali bv the action of quick-lime, and even took advantage of this property of lime to give to soda (carbonate of soda) a degree of causticity which deceived the purchasers of this article as to its real value. The arts of making earthenware, glass (both colorless and colored), porcelain, and various pigments, and certain processes in dying, were brought to a state of perfection not exceeded, nay, in some instances, scarcely equalled, by artists of the present day. These and other processes were not only invented without the aid science, that term being accepted in its ordinary sense of inductive systematic truth, but they were also practised for ages before even an attempt was made to dis- cover the causes of the varied phenomena presented in the different operations. The successive improvements fortunately achieved in some of the processes were contrived, like each original process itself, by chance, and consequently, in general, at the expense of great labor ; the experimentalist being guided in his researches for improvements by no fixed principles or general laws. Where improvements are to bo. the result of accidental observations, they must of necessity be rarely made. The Chinese, it is true, practise certain chemical arts with surprising success ; but these arts are no further advanced now than they have been for ages past; not because they have attained perfection, but from the want of recognition of the principles on which the processes depend. In departing from, or even in merely modifying, the original process, there is a danger of losing it altogether. This is the reason, we apprehend, of the loss of some of the most refined processes of the ancients during the middle ages. But since chemistry has existed as a science founded on certain laws, and since the properties of individual substances have been so minutely studied that the action of two or more bodies on each other in certain circumstances can be partly predicated before ascertained by experiment, new processes are 2 PRELIMINAEY OBSERVATIONS. devised and others improved by a scientific deduction from recognised princi- ples, and from the known properties of the substances employed in the art or manufacture. Refine'd as were some of the processes of the ancients, there are those prac- tised in the present day which it is difficult to conceive could have been in- vented by any number of hazard experiments on substances presented by na- ture. They were devised and improved by a logical induction from known principles or admitted theories. The greater number of our calico-printing processes are illustrations of our assertion. For instance, we can not imagine that any number of chance experiments would have led to the procuring from chrome-iron ore (a black heavy mineral), by the action, first of an alkali, and afterward of an acid, of a substance by which, when applied in a proper man- ner, the calico-printer is enabled to produce a white pattern on a piece of cloth died with indigo-blue. This was, of course, discovered experimentally, but by experiments founded on scientific principles. Again, the common process for preparing carbonate of soda from common salt, invented toward the close of last century by Leblanc and others, which is scarcely second in importance to any chemical manufacturing process, could hardly have been devised other- Avise than by a series of experiments conducted on certain chemical principles. This process consists, first, in the conversion of common salt to sulphate of soda by the action of sulphuric acid ; in the next place, in the conversion of sulphate of soda to sulphuret of sodium by the action of carbonaceous matters at a high temperature ; and, lastly, in the conversion of sulphuret of sodium to carbonate of soda by the action of chalk. The last two operations are now conducted simultaneously. Such a process as this we can hardly conceive to have been discovered by hazard experiments. The theoretical principles on which a process is invented may be false, and yet the process itself turn out successful. Thus it was with the original pro- cess for obtaining sulphuric acid by the combustion of sulphur with nitre, which was contrived by Lefevre and Lemery soon after the development, by Stahl and Beccher, of the theory of phlogiston. According to that theory all combustible bodies are compounds oi phlogiston, or the principle of inflamma- bility (which is parted with in the act of combustion), and some elementary basis, which is, in fact, the material product of the combustion. The latter is now known to be the compound body, being composed of the combustible matter and oxygen ; the act of combustion is merely the combination of oxy- gen with the combustible. But consistently with the then prevailing theory of phlogiston, sulphur is a compound body, being composed of phlogiston united with (what is now termed) sulphuric acid : to procure the latter, there- fore, it became necessary to withdraw phlogiston from the sulphur. Now nitre was considered to be a substance possessed of a dephlogisticating property in an eminent degree ; and, when a mixture of sulphur and nitre was set on fire over water, sulphuric acid was found to be produced. Here the expected result was obtained, but the principle which led to the experiment was errone- ous ; for the nitre, instead of withdrawing anything from the sulphur, actually imparts oxygen to it : sulphuric acid being produced by the combination of the sulphur with a portion of the oxygen contained in the nitre. Such is a simple expression of the first changes in the process ; afterward they become sonae- what more complicated. The reason why the process was successful, while the theory on which it was founded is false, is obvious. The terms a dephlo- gisticating body (on the theory of phlogiston), and an oxidating body (accord- mg to our present views, are synonymous : as are also a dephlogisticated and an oxidated substance. It can not be denied, however, that valuable processes and improvements have been devised of late years independently of chemical hypotheses and principles. The amalgamation ffocess of Hernando Velasquez for obtaining silver from the ore (practised in Mexico) must ever be considered a wonderful instance of the discovery, by chance, of a process dependant in its details on complicated chemical agencies. The inventor was entirely unacquainted with theoretical chemistry, and was led to his process by experiment after exper- CHEMICAL AFFINITY. 3 iment without connexion, and guided it would seem, by no general principles. But so refined is the process that its theory has only been developed of late years, with the united efforts of Gay-Lussac, Humboldt, Karsten, Boussingault, and Sonneschmidt. Instances like this, are, however, very rare. Although many processes in the chemical arts are dependant for their suc- cessful practice chiefly on a knowledge of principles, yet, in general, the ambition of those engaged in working the process is to attam dexterity in the mechanical operations, without the smallest endeavor to comprehend the most obvious principles of their process. Although chemistry is making rapid advances, many of the arts dependant on the science are stationary, the artisan or manufacturer being, generally, too ignorant of chemistry to know where to look for improvements. By this neglect of the practical man, scientific chem- istry is also much retarded. In a die-house and a calico-print-work, for in- stance, how many interesting phenomena pass unobserved, or at least with- out being investigated, which, if carefully examined by a scientific chemist, might prove the sources of brilliant discoveries, conducive no less to the advancement of theoretical chemistry than of the chemical art itself ! To consider minutely the general principles of chemical philosophy would be inconsistent with the plan of the present work. But for facility of reference, and for the convenience of those who have not especially studied the prin- ciples of theoretical chemistry, it has been considered proper to commence with a few observations on the nature of chemical affinity, and on the laws which govern, and the phenomena which accompany, the chemical combina- tion of diff'erent substances. All other important theoretical considerations affecting the various practical subjects treated of m this work will be adverted to under the respective articles. CHEMICAL AFFINITY. The vast variety of substances by which we are surrounded, animate and inanimate, solid, liquid, and gaseous, are composed of, comparatively, a very small number of elements or simple substances ; of bodies, that is, which con- tain one kind of matter only. According to the present state of our knowledge, the number of elements does not exceed fifty-six ; and, as the only evidence we can obtain of the elementary character of a substance is of a negative kind, namely, that we are unable now to decompose it, or resolve it into other kinds of matter, it is not unlikely that some of the substances now considered as elements may hereafter turn out to be compound. But until such is proved to be the case, it is proper to consider them as simple substances. Every substance in nature, then, is either an element, or else it results from the combination of two or more elements with each other. This union of the elements does not take place indiscriminately : some of them when brought into contact exhibit a remarkable proneness to unite, while others may be mixed most intimately without the occurrence of combination. Peculiar attachments and indiff"orences certainly subsist between different substances. The former may be conveniently distinguished as chemical affinity, or chem- ical attraction. The exertion of this force is not confined to simple substances merely ; compound bodies, as sulphuric acid and water, for instance, are equally subject to its influence. When the constituents of a compound body are thus held together by chem- ical affinity, the resulting substance is called a chemical compound, to distin- guish it from a mechanical compound. The latter is a mere mixture of diff'er- ent substances, which are held together by no chemical affinity, but, if the body is a solid or a liquid, merely by the force of cohesion or of adhesion. Chemical compounds are definite combinations of two or more elements, united in a particular manner, and always, when forming the same compound, in fixed proportions ; the substance formed always wants the chemical characters of its constituents, and in the act of combination there is commonly a very obvious change, even in the most general, of physical properties. Mechanical compounds, which constitute by far the greater number of natural substances, 4 PRELIMINARY OBSERVATIONS. are on the contrary indefinite mixtures of elementary bodies or chemical com- pounds of the elements, retaining both the form and the properties of their constituents. The atmosphere around us, for example, is a mechanical mix- lure of two elementary gases, oxygen and nitrogen. These same elements when chemically united in a certain proportion give rise to one of the most corrosive of all acids, namely, nitric acid, or aqua-fortis as it is popularly designated. Again, the rock granite is a mechanical mixture of three chemical com- pounds : 1°, quartz, which is a chemical combination of two elements, silicon and oxygen ; 2°, felspar, which is composed of four elements, silicon, oxygen, potassium, and aluminum ; and 3°, mica, composed of six elements, namely, silicon, oxygen, iron, aluminum, magnesium, and potassium. The three minerals, quartz, felspar, and mica, each a chemical combination, thus con- stitute the rock granite by their mechanical admixture. The nature of chemical affinity and the characters of chemical compounds may be conveniently considered under the four following heads : — \ °, Chem- ical affinity is exerted with different degrees of force between different sub- stances. 2°. The union takes place in certain fixed and definite proportions. 3°, The resulting compound always differs essentially in chemical, and often in physical properties from its constituents; and 4", The union may take place indirectly by substitution, or directly. 1. Chemical affinity is exerted with different degrees of force between different substances. — On examining various metallic oxides it is found that the oxygen and metal are united together with very different degrees of intensity in the different oxides. Thus, oxide of silver is easily decomposed when heated to redness, oxygen gas being given off and metallic silver remaining behind. Oxide of copper, on the contrary, is not reduced to the metallic state at the highest temperature to which we can expose it. It is therefore reason- ably inferred that oxygen has a more powerful affinity for copper than for silver. Again, oxide of copper is reduced to the state of metallic copper with the greatest facility if heated to redness in a glass tube through which a stream of hydrogen gas is made to pass. But potash, the oxide of potassium, does not undergo the smallest decomposition under such circumstances. Hence oxygen has a more powerful affinity for potassium than for copper. The truth of the proposition is clearly exhibited in the decomposition of a compound substance by another body. On introducing metallic copper into a solution of chloride of mercury (corrosive sublimate), the latter is decomposed, metallic mercury is precipitated, and a proportional quantity of copper is dis- solved, uniting with chlorine to form chloride of copper. But chloride of cop- per may be decomposed in a similar manner by metallic tin, and chloride of tin by metallic zinc. The relative affinity of these metals for chlorine may there- fore be arranged in the following order. Chlorine, 1. Zinc, 3. Copper, 2. Tin, 4. Mercury: a solution of chloride of zinc is not decomposed by any of the metals men- tioned, while a solution of chloride of mercury is decomposed by each. A series of tables was contrived by Geoffroyand Bergmann, founded on such experiments as these, intended to exhibit the order of affinity of different bases* for an acid, aad of different acids for a base. The name of an acid or a base is put at the head of a list, and after it the names of all the bases or acids in the order of their affinity. For example, the affinity of alkalies and earths for sulphuric acid is expressed as follows : — Sulphuric Jlcid. 1. Barytas, 5. Lime, 2. Strontian, 6. Magnesia, 3. Potash, 7. Ammonia. 4. Soda, * By a base is meant an alkali, or a metallic oxide which has a tendency to unite with an acid and thus form a salt. Thus potash is the base of nitre, or nitrate of potash ; oxide of lead is the base of sugar of lead, or acetate of lead. CHEMICAL AFFINITY. 5 Barytes, the first in the list, is capable of taking sulphuric acid from the sul- phate of either of the bases which follow, while sulphate of barytes is not de- composed by any other base. Potash has a stronger affinity for sulphuric acid than the bases which follow, but not so strong as that of barytes. The exper- iments are supposed to be made on aqueous solutions of the several sulphates. Such tables, however, show the order of decomposition, and the relative force of affinity, in one set of conditions only ; for when the same two substan- ces are brought together under different circumstances, very different reactions may ensue. Of this, Bergmann himself was aware, and hence gave two lists or columns in some of his tables of affinity ; one showing the order of decom- position when the substances are mixed together dissolved in water, as above, and the other when mixed in a dry state and strongly heated. Boracic acid possesses very feeble acid characters when dissolved in water ; it is hardly able to destroy the alkaline properties of potash or soda ; but at a red heat, from its great fixedness, it comports itself as a most powerful acid. If dry nitrate of ammonia and carbonate of lime are mixed and exposed to heat, a decomposi- tion takes place with production of nitrate of lime and carbonate of ammonia; from which circumstance it would be inferred that nitric acid has a stronger affinity for lime than for ammonia, or carbonic acid a stronger aflRnity for am^ monia than for lime. But if the conditions in which the nitric acid, carbonic acid, lime, and ammonia, are brought together, are altered, very different re- sults take place. On mixing aqueous solutions of nitrate of lime and carbonate of ammonia, carbonate of lime is precipitated, and nitrate of ammonia remains in solution. Again, carbonate of potash dissolved in water is instantly decom- posed on the addition of acetic acid, carbonic acid gas being evolved and acetate of potash formed. Acetic acid manifests in this case a stronger affinity for pot- ash than carbonic acid does. Butif a stream of carbonic acid gas is passed through a solution of acetate of potash dissolved in alcohol, the carbonic acid seems to be the most powerful, for carbonate of potash is formed, and acetic acid liberated. The result in the latter case seems to depend on the insolubility of carbonate of potash in alcohol. If the composition of two salts is such as to permit the formation of an insoluble product by their mutual decomposition (as in the case of carbonate of ammonia and nitrate of lime), such a change is sure to take place when solutions of the salts are mixed. The order of decom- position seems to be decided, in such a case, not by the superior affinity of this or that acid or base, but by the tendency to the formation of an insoluble sub- stance. These and many other examples, which might be adduced if necessary, show that though chemical affinity is exerted between different bodies with different degrees of force, yet accessory circumstances do sometimes materially affect the relative affinities of different substances. 2. The chemical union of substances takes place in certain fixed and definite proportions. — The circumstance, that the proportions in which two or more Bodies can unite chemically are limited on both sides, has been already alluded to as a distinction between a chemical and a mechanical compound (page 3). Common salt, for instance, by whatever process it may be formed, is invariably composed of 60 parts of sodium, and 40 parts of chlorine; and, so far as is known, these elements are incapable of uniting in any other proportion. Pure carbonate of lime, whether formed ages ago by the hand of nature, or quite re- cently by the chemist, whether in the form of white marble, chalk, or a stalac- tite, whether in the six-sided prism of arragonite, or in the rhomboidal crystal of calc spar, is always composed of 43"7 parts of carbonic acid and 56"3 parts of lime. That the composition of chemical combinations is always fixed and invariable, is constantly borne out by analyses ; and from this definite nature of chemical combination is derived in a great measure the character of chemistry as an exact science. The same element combines with very different quantities of different sub- stances. This is shown in the following table of the composition of water, sulphuretted hydrogen, hydrochloric acid, and hydriodic acid, each of which substances contains hydrogen as a common constituent. 6 PRELIMINAEY OBSERVATIONS. Hydrogen Oxygen . . Water. .. IM 88-9 Hydrogen Sulphur. . , Sulphuretted Hydrogen. 5-9 94-1 100-0 100-0 Hydrogen Chlorine . Hydrochloric Acid. Hydriodic Acid. .... 0-79 .... 99-21 2-7 97-3 Hydrogen Iodine... . 100-0 100-00 By such a mode of expressing the composition of these bodies no simple re- lation is perceptible between the respective quantities of hydrogen in the differ- ent compounds. But if a constant number, say 1, is given to hydrogen, then it will be seen that 8 parts of oxygen, 16 parts of sulphur, 35-5 parts of chlorine, and 126 parts of iodine, combine respectively with 1 part of hydrogen. Now the numbers mentioned are in some degree characteristic of the substances to which they are attached ; for, on examining the composition of the compounds which these elements form with lead, copper, and potassium, it is found that the above numbers of parts of oxygen, chlorine, &c., actually combine with the same quantity of the metal, although the amounts of the different metals in the respective compoimds are not the same. Thus: — By extending this inquiry to other substances, a series of numbers may be obtained, which exhibits either the exact relative quantities in which bodies unite to form chemical combinations, or else multiples of such quantities. These numbers are called combining proportions or equivalents. The latter term is employed to signify that the combining proportion of one body has the same value, or is, in one sense, equivalent to that of another body, and may be substituted for it in combination. The same quantity of potassium which unites with 35-5 parts of chlorine, also combines with 126 parts of iodine; therefore the numbers 35-5 for chlorine, and 126 for iodine, are as it were equiv- alent to each other, as they have an equal power in combining with, and alter- ing the nature of, 39 parts of potassium. Hitherto we have considered the equivalent numbers with reference to hy- drogen as unity, but this is quite arbitary, and any other series of numbers may be used, provided the proper relation between them is preserved. Thus it is the practice of some chemists to form the series with reference to oxygen as 100, and others make oxygen 1. The series of numbers in which hydrogen is con- sidered as 1 is called the hydrogen scale of equivalents ; the others are called the oxygen scales. The hydrogen scale will be employed in the present work. The following table contains a list of all the elements which have been discov- ered up to the present time, with their combining numbers on both the hydro- gen and oxygen scales : — 8 parts of oxygen 35-5 parts of chlorine 16 parts of sulphur 126 parts of iodine 1 part of hydrogen, 104 parts of lead, 32 parts of copper, 39 parts of potassium. CHEMICAL AFFINITY. TABLE OF CHEMICAL EQUIVALENTS. 7 Names of Elements. Aluminum. Antimony . Arsenic . . . Barium . . . Bismuth . . . Boron . . . . Bromine . . Cadmium.. Calcium . . Carbon.. . . Cerium . . . Chlorine . . Chromium Cobalt Columbium Cupper.. . . Didymium . Fluorine . . Glucinum . Gold Hydrogen . Iodine . . . . , Iridium . . . , Iron Lantanum. , Lead Lithium . . , Magnesium Equivalents. Oxygen = 100. 171-2 1612-9 940-1 856-9 886-9 136-2 978-3 696-8 256-0 75-0 574-7 442-6 351-8 369-0 2307-4 395-7 ? 233-8 331-3 2486-0 12-5 1579-5 1233-5 339-2 ? 1294-5 80-3 158-3 Hydrogen 13.7 129-0 75-3 68-7 71-1 10-9 78-4 55-8 20.5 6-0 46-05 35.5 28- 2 29- 6 184-9 31-7 ? 18-7 26- 5 199-2 1-0 126-6 98-8 27- 2 ? 103-7 6.4 12-7 Names of Elements. Manganese . Mercury . . . Molybdenum Nickel Nitrogen . . . Osmium ... Oxygen .... Palladium . . Phosphorus . Platinum. . . , Potassium .. , Rhodium Selenium. . . , Silicon Silver , Sodium . , Strontium . . . Sulphur Tellurium .. . Thorium . . , . Tin Titanium . . . Tungsten Vanadium. , . Uranium .. . . Yttrium Zinc Zirconium . . Equivalents. Oxygen Hydrogen = 100. 345-9 27-7 1265-8 101-4 598'5 48-0 369-7 29-6 175-0 14-0 1244-5 99-7 100-0 8-0 665-9 53-4 392-3 31-4 1233-5 98-8 489.9 39-2 651-4 52-2 494-6 39-6 277-3 22-2 1351-6 108-3 290-9 23-3 547-3 43-8 201-17 16-1 801-76 64-2 744-9 59-8 735-29 58-9 303-66 24-3 1183-0 94-8 856-9 68-7 2711-4 217-3 402-5 32-2 403-2 32-31 420-2 33-7 The principal law which governs chemical combinations is, that bodies-, unite chemically with each other only in the pro-portion of their equivalents, or in multiples of their equivalents, and in no intermediate proportions. This law is well illustrated by the five compounds which are formed by the union of oxygen and nitrogen. The first of these, protoxide of nitrogen, or nitrous oxide, contains 14 parts of nitrogen and 8 of oxygen ; that is, one equivalent of each constituent. The second combination of these elements, deutoxide of nitrogen, or nitric oxide, confains 14 parts of nitrogen and 16 of oxygen; that is, two equivalents of oxygen and one of nitrogen. The third, nitrous acid,, contains 14 parts of nitrogen and 24 of oxygen, or three equivalents of oxygen and one of nitrogen. The fourth combination, peroxide of nitrogen, contains 14 parts of nitrogen or one equivalent, and 32 parts of oxygen or four equiva- lents. The fifth and last, nitric acid, of which aqua-fortis of commerce is a solution in water, is composed oi 14 parts of nitrogen or one equivalent, and 40 parts of oxygen or five equivalents. In the five compounds, therefore, one eq, of nitrogen is combined respectively with one, two, three, four, and five equivalents of oxygen. The law illustrated in the last paragraph applies equally to combinations among bodies themselves compound. The equivalent of a compound body is always the sum of the equivalents of its constituents. Thus the equivalent of water on the hydrogen scale is 9 ; water being composed of one eq. of hydrogen = 1, and one eq. of oxygen = 8. The equivalent of potash is 47 ; that alkali containing one eq. of potassium a= 39, and eq. of oxygen = 8. Now 47 parts of potash combine with exactlj 8 PRELIMINARY OBSERVATIONS. 9 parts of water to form the hydrate of potash or compound of potash and water. As sulphuric acid is composed of one equivalent of sulphur = 16 and three equivalents of oxygen = 24, the equivalent of sulphuric acid is 4o! 10 form neutral sulphate of potash, consisting of one eq. of potash and one eq. 01 sulphuric acid, 47 parts of potash combine with exactly 40 parts of sulphuric acid, and the equivalent of the resulting sulphate of potash is 87. An equiva- lent of sulphuric acid unites in like manner with 9, 18, and 27 parts of water to form hydrates containing respectively one, two, and three equivalents ol water. Here is, therefore, an example of combination in multiple propor- tions between bodies themselves compound. However great may be the number of the equivalents of the elements of a compound body, the universal- ity of the law that the equivalent of the compound is the sum of the equiva- lents of its constituents is by no means affected. 3. The resulting compound always differs in chemical, and often in physical properties, from its constituents.~A change in the properties of the combining substances is the leading circumstance that distinguishes chemical combination from mechanical admixture. In the former, the change is never wanting ; in the latter, the properties of the mixture are the mean of those of its con- stituents. We should not suppose from its appearance that common salt is a compound body : much less that this harmless substance is composed, on the one part, of a body which when uncombined is a highly irritating and noxious gas (chlorine), which causes instant death if inhaled; and, on the other part, of a metal (sodium) as bright as silver, which has the extraordinary property of taking fire when moistened with water. Sometimes a change in density and form attends the chemical combination of two substances. Thus two gases may give rise to a solid, as happens when ammoniacal gas and muriatic acid gas are mixed together. A solid sometimes assumes the gaseous state by combining with a gas ; thus sulphur and char- coal form gases by combining with hydrogen gas. Gases sometimes unite, however, without any alteration in bulk. When combination takes place among solids and liquids with the formation of a solid or liquid, condensation IS a more frequent result than expansion; and, if other evidence of chemical combination is wanting, that of the occurrence of a condensation may be con- si-dered conclusive. Thus the contraction which results when water and alco- hol are mixed in certain proportions, is considered, of itself, a sufficient proof of the chemical union of the water with the alcohol. A change of color very frequently attends chemical combination ; sulphur forms a red and black compound with mercury, black compounds with lead and copper, a white compound with zinc, and two yellow compounds with arsenic. Iodine, whose vapor is violet colored, forms a white compound with copper, a yellow compound with lead, and a scarlet compound with mercury. An example of a change in properties is afforded, in short, by almost every case of chemical combination. Change of temperature is a frequent result of chemical action. It is said that the direct chemical combination of two or more substances never occurs without the development of a certain amount of heat, on which circumstance depend all our ordinary artificial modes of obtaining heat. The production of neat in the act of combination may be sometimes referred partly to the conden- sation which usually takes place, the compound formed having a smaller spe- cific heat than its constituents ; but in a great many cases this explanation is inadmissible. The true cause of the evolution of heat in chemical combina- tion still remains to be accounted for. The intensity of the heat developed through the combination of two bodies differs greatly, according to the circum- stances in which the combination takes place ; but it is a remarkable fact that the quantity or absolute amount of heat (to apply to an imponderable agent terms which belong to material substances) is the same for like quantities of the combining substances, whether the union takes place rapidly or slowly. Oxygen and hydrogen gases may be made to unite and form water quickly, as by contact with flame or spongy platinum ; and slowly, by placing the mixed gases in contact with some earthy mould. In the first case, the intensity of CHEMICAL AFFINITY. 9 the heat produced is sufficient to fuse with facility many substances which are quite intusible at the highest temperature of a smith's forge : hi the second case, the temperature rises very little above that of the surrounding atmo- sphere. But there is reason to believe that the actual quantity of heat developed is the same in both cases for like quantities of the gases ; the difference is only in intensity or state of concentration ; the slowness of the action in the second case allowmg the distribution of the heat to surrounding bodies to a far greater extent than could possibly be the case in the rapid combustion of the gases ihe superior vivacity of the combustion of tallow, a match of wood, &c in oxygen gas compared with air, depends entirely on the same circumstance. Apiece ot charcoal burns with far more heat and light in oxygen gas than in air ; but it unites with oxygen, or is consumed, proportionally faster. 4. Chemical union may take place indirectly by suhstUution, or directlv— ihe lollowing examples will serve to illustrate this proposition. When the two component parts of common salt, chlorine and sodium, are placed in con- tact, a direct conibination instantly ensues. But the union of the chlorine and sodium can be effected in a very different manner, with the formation of the same compound. The combination takes place indirectly, for instance, when hydrochloric or muriatic acid (a compound of hydrogen and chlorine^ is brought into contact with soda (a compound of sodium and oxygen). Again if a mixture of iron filings and flowers of sulphur is projected ^to a crucible heated to dull redness, a direct combination of iron and sulphur ensues, the su phuret of iron bemg formed. But the same compound is formed when a solution of sulphurei of potassium (a compound of sulphur and potassium) is mixed with a solution of chloride of iron (a compound of iron and chlorine) indirect combinations of this nature are characterized by tAvo imnortant Hr- cumstances. While union is taking place on the one hand, there is neces- sarily decomposition on the other ; for the substances which are to unite are brought into contact in a state of previous combination with other sub- stances, in the formation of common salt or chloride of sodium by hvdro- cMoric acid and soda, there must be a decomposition both of the hydrochloric acid and the soda m order that the chlorine and sodium may unite S Hite/J ? ''.f 'Ti!' sulphuret of potassium with clifoude of iron the sulphur and iron can not unite Avithout a decomposition of he sulphuret of potassmm and of the chloride of iron. As there are two dis- unions, so there are likewise, generally, two combinations. When hydrochloric acid is made to act on soda, union is effected, not only between the chlorine monr.^ wTt'l. ^^'^T? hydrochloric acid unites at the same momem with the oxygen of the soda, to produce water. Chloride of sodium and water, therefore, are the products of the action of hydrochloric acid on soda ihe manner m which the decompositions and combinations occur is more clearly exhibited in the subjoined diagram. The first column contains the llTl ^^i^^:^"^ o'^Jgi"^! substances; the second, the names of their constituents; and the third, the names of the compounds which are formed, the lines indi^ catmg how the constituents of the original substances become arranged. „ , ^- HI. Hydrochloric C Hydrogen Water acid I Chlorine Soda 5 Soda Chloride of sodium. In like manner, as two decompositions occur when sulphuret of notas^ium and chloride of iron are made to act on each other, so are there likrA^se tw^ at'urS; ^"^P^^^ °f the sulphu7I oVpo- tassium unites with the iron of the chloride of iron, the chlorine of the latter unites_ with the potassium of the sulphuret of potassiumTo ?orm chl^^^^^^^^^ potassium. The amiexed diagram wilHUustrale these changes 10 PRELIMINARY OBSERVATIONS. Sulphuret of potas- sium < Potassium ( Sulphur Chloride of potassium. Chloride of iron f Chlorine \ Ij on Sulphuret of iron. Such reactions as these are described as double decompositions or double substitutions. But another kind of indirect union frequently occurs, in which there is a single decomposition and a single substitution, only one of the two substances which are to be united being then in a state of previous combina- tion with another substance. The action of iodine on sulphuretted hydrogen, explained in the annexed diagram, is of this nature. Sulphuretted Hydro- ( Sulphur Sulphur (free) gen ( Hydrogen — Iodine ' Hydriodie acid. In this example there is a single union and a single decomposition ; or, in fact, merely a substitution of iodine for sulphur in the sulphuretted hydrogen. A great number of compounds may be readily formed by reactions of this kind, all attempts to obtain which by direct combinations have been fruitless. Solution. — The attractive force by which one body is dissolved in another in the liquid state has been considered by some to be identical with chemical affinity. — One of the characters of a chemical union is certainly in some degree fulfilled in solution, namely, change in properties ; but several circumstances manifest a difference between the two forces. In most cases of solution there is not only no increase of temperature, but a production of cold from the abstraction of a certain amount of heat from surrounding bodies, which is rendered latent by the dissolved substance, as always happens when a body passes from the solid to the liquid condition. In solution, the union takes place in no fixed proportions : a certain quantity of water can dissolve or com- bine with any quantity of common salt less than 37 per cent, of the weight of the water ; and the solution has the same appearance, whether it contains a large or a small proportion of salt. Water, it is true, has a constant max- imum solvent power for every soluble salt at a particular temperature ; but the quantity of water and the quantity of salt in solution bear, in general, no simple relation to the chemical equivalents of these substances. Again, chemical combination takes place with so much the more energy as the prop- erties of the combining substances are more opposed ; but solution on the contrary, with a readiness corresponding to their similarity in properties. Thus, to dissolve combustible bodies containing a large proportion of carbon and hydrogen, such as resin, fixed oils, essences, and caoutchouc, combustible liquids must be used, as alcohol, ether, naphtha, and oil of turpentine. To dissolve a metal, another metal must be used, as mercury : * oxidated bodies, as most salts, require oxidated solvents, as water and acids : very few saline matters soluble in water are also soluble in ether and in oils. An essential difference exists, therefore, between the act of solution and that of chemical combination ; the former being exerted by preference between similar, and the latter between dissimilar particles. With a single exception, the solubility of a salt varies with the temperature of the solvent, the largest amount being taken up at the higher temperature. The exception to this law referred to is in the case of common salt, of which the same proportion is dissolved by water at all temperatures below 230° Fahr- enheit. In another case, that of sulphate of soda, the solubility of the salt increases rapidly up to the temperature 92° Fahrenheit, at which it is at the * When a metal is said to be dissolved in an acid, as copper in nitric acid, for example, it is, in reality, not the metal itself which dissolves, but a substance formed by the chemical action of the acid on the metal as nitrate of copper. PROXIMATE AND ULTIMATE CONSTITUENTS. 11 maximum : the solution at that temperature contains 52 parts of dry sulphate to 100 parts of water, but at a higher temperature water is incapable of dis- solving so large a proportion of that salt. In all other cases, so far as is known, the amount of a salt dissolved increases with the temperature, unless a de- composition and formation of a less soluble substance take place under the influence of the heat. Advantage is taken of the increased solubility of salts at a high temperature to effect their crystallization. When a solution of a salt saturated (containing its maximum quantity of the salt) at a high temperature is allowed to cool, it retains in solution only that quantity proper to its reduced temperature : the excess is deposited, it may be in the state of crystals. Thus a saturated solution of Epsom salts at the temperature of 212^ contains 74 parts of that salt to every 100 parts of water ; but, on being cooled down to 50° Fahrenheit, 44 parts are deposited in crystals, 100 parts of water at 50° being incapable of holding in solution more than 30 parts of Epsom salts. Some cases of solution, however, are undoubtedly accompanied with the chemical union of the solvent with the body dissolved ; as, for example, when dry potash or dry chloride of calcium is dissolved in water. In these, as in other cases of direct chemical combination, there is development of heat, while cold is produced in a case of solution merely. When such a combination takes place, it is, strictly speaking, the compound formed which dissolves ; as, the hydrate ol^ potash, or the hydrate of chloride of calcium. Proximate and ultimate Constituents, and Symbols. — The composition of a compound body may be expressed in the simple elements which form what are called its ultimate constituents, and also very frequently by those compound bodies which by their immediate union compose the substance in question The latter are called proximate constituents. Of dry sulphate of magnesia, for instance, the ultimate constituents are sulphur, oxygen, magnesium : the proximate constituents are sulphuric acid and magnesia : thus, „ , , . . , ( Sulphur Sulphuric acid J q^^^^^ Sulphate of magnesia Magnesium Oxygen. f Magnesia The composition of crystallized alum is more complex : thus, Proximate Constituents. Alum • Sulphate of alumina Sulphate of potash Sulphuric acid Alumina Sulphuric acid Potash Ultimate Ccmstituents. Sulphur Oxygen ( Alumi I Oxyge Aluminum jen Sulphur Oxgen Potassium Oxygen Water 5 Hydrogen ■ • ; Oxygen. Now the composition of crystallized alum may be expressed in so many parts of sulphur, oxygen, aluminum, potassium, and hydrogen ; or in so many parts of sulphuric acid, potash, alumina, and Avater ; or in so many parts of sulphate of alumina, sulphate of potash, and water. The expression of the composition of a substance which is a chemical, and 12 PRELIMINARY OBSERVATIONS. not a mere mechanical compound, should include, if possible, the atomic com^ position of the substance, that is, the relative proportions of the equivalents of its constituents, as well as the ultimate or per-centage composition. Much more information may be conveyed in such a statement than in that of the per-centage composition alone, represented either according to the proximate or ultimate constituents. The reasons of this will be obvious from the con- siderations offered at page 5, et seq., on the definite proportions in which chemical union takes place. As an example, the composition of crystallized sulphate of magnesia may be represented thus : Equivalent Mamie Per-centage or atom. weight. composition. Magnesia 1 21 16-1 Sulphuric acid 1 40 32-1 Water 7 63 50-8 Sulphate of magnesia.... 1 124 100-0 The readiest method of representing the composition of a compound body is by the association of symbols of its elementary or proximate constitiaents. Each elementary substance is represented by a particular symbol, which is the initial letter of its Latin name ; but when the names of two or more elements begin with the same letter, the distinction is made by an additional letter in a smaller character. Thus, phosphorus being represented by the letter P, plati- num is indicated by Pt, and Palladium by Pd ; C being the symbol for carbon, calcium is represented by Ca, chlorine by CI, and cobalt by Co ; the small let- ter is significant only when in conjunction with the large letter. The follow- ing table includes the symbols of all the elementary substances known. : Aluminum Antimony (Stibium) Arsenic Barium Bismuth Boron Bromine Cadmium Calcium Carbon , Cerium Chlorine Chromium Cobalt , Columbium (Tantalum), Copper (Cuprum) Didymium Fluorine Glucinum Gold (Aurum) Hydrogen Iodine Iridium Iron (Ferrum) Larntanum Lead (Plumbum) Lithium Magnesium Syrnb. Al Sb As Ba Bi Bo B Cd Ca C Ce CI Cr Co Ta Cu Di Fl Gl Au H I Ir Fe La Pb Li Mg Manganese Mercury (Hydrargyrum) . Molybdenum Nickel Nitrogen Osmium Oxygen Palladium Phosphorus Platinum Potassium (Kalium) Rhodium Selenium Silicon Silver (Argentum) Sodhim (Natrium) Strontium Sulphur Tellurium Thorium Tin (Stannum) Titanium Tungsten or Wolfram. . . . Vanadium Uranium Yttrium Zinc Zirconium CHEMICAL SYMBOLS. 13 The foregoing symbols represent, at the same time, the chemical equivalents of the elements. Thus the letters H and 0 express not hydrogen and oxygen indefinitely, but a single equivalent of these elements : that is, on the hydrogen scale, 1 part of hydrogen and 8 parts of oxygen ; and on the oxygen scale, 12.5 parts of hydrogen and 100 parts of oxygen. The symbol of itself expresses only one equivalent, and, when several equivalents are to be indicated, this symbol may be repeated ; thus, 000 would signify three equivalents of oxy- gen ; or else a figure showing the number of equivalents may be placed imme- diately before the symbol, thus, 30 ; or, what is preferable, a smaller figure may be placed after the symbol, either above or below it, thus, 03 or O3. Now the association of symbols either with or without the + sign, signifies combination : thus, the formula K+0 or KO represents a compound of one equivalent of potassium and one equivalent of oxygen, which is the alkali potash. H-f-Cl or HCI represents hydrochloric acid, composed of one equivalent of hy- drogen and one equivalent of chlorine. SO3 signifies acid, a compound of one equivalent of sulphur with three equivalents of oxygen. Something more may be expressed in symbolic notation than the names of the elements of a compound body and the numbers of their equivalents; the constitution of the compound, or the mode in which the elements are arranged, may also be represented. The formula, Fe S04 expresses truly the composition of proto-sulpliate of iron (copperas), but not the arrangement of the elements ; on the contrary, the formula FeO^-SOs or FeO, SO3 signifies that the salt in question is composed of oxide of iron and sulphuric acid, the -f- sign, or the comma, indicating a distribution of the elements of sulphate of iron into its proximate constituents, oxide of iron and sulphuric acid. The small figure on the right hand of a symbol does not apply to any other symbol than that 10 which it is immediately attached ; but a large figure placed before the symbol, like a co-eflFicient in algebra, affects the whole com- pound expressed, or at least all the symbols before the first comma, or plus sign. Thus 3N05 and 2S03 signify three equivalents of nitric acid and two equivalents of sulphuric acid. The formulse 2H0, SO3 and 2HO-4-S03 express not twice HO, SO3 but a compound of two equivalents of water with one equivalent of sulphuric acid : the SO3 not being eflfected by the figure 2 at the beginning, because of the interposition of the comma or plus sign. To make the whole symbol subject to the influence of the figure at the beginning, it should be enclosed within a parenthesis, thus 2(H0, SO3 ) represents two equiv- alents of hydratcd sulphuric acid, and 2(MgO, S03 +7H0) two equivalents of crystallized sulphate of magnesia. The following formulse of some minerals afford examples of the application of these rules : Felspar, KO, SiOg 4- AI0O3, SSOg . Analcime. SNaO, 2S1O3 + SAlgOa, 2Si03 -f- 6H0. Apophyllite, 8(CaO, 8103) + KO, 28103 + 16H0. To avoid mdistinctness or confusion from the great length of the formulae of some bodies, several abbreviations have been introduced. "When two equiva- jents of an element are to be expressed, a line is sometimes drawn through the symbol or placed under it ; thus, H and H signify two equivalents of hy- drogen. An equivalent of oxygen in a compound is expressed by a dot placed over the symbol of the other element, the number of dots being the same as the number of equivalents of oxygen ; S expresses sulphuric acid, and K pot- ash ; therefore K S stands for sulphate of potash. Alum is represented by K S, Al 3S+24H, Sulphur in a compound is sometimes represented in a simi- lar manner by a comma placed over the symbol of the other element, selenium by the sign — , and tellurium by the sign+; but such abbreviations will not be made use of in the present work. The vegetable and animal acids are conveniently represented by their initial letter with a dash placed over it ; thus, A stands for acetic acid, C for citric acid, Tar for tartaric acid, and F for formic acid. 14 PRELIMINARY OBSERVATIONS. In addition to the table of the equivalents of the elements at page 16, the following, which contains the equivalents of several acids and bases, will be found convenient for reference. TABLE OF EQUIVALENTS. L ACIDS. Acetic (dry), A= (C4H3O3) 51-0 Arsenic, As O5 115-4 Arsenious, As O3 99-4 Benzoic, Bz = (C14H5O3) 113-0 Boracic, BO3 34-9 Bromic, Br O5 118-5 Carbonic, C O2 22-0 Chloric, CI O5 75-5 Chromic, Cr 0 3 52-2 Citric,'C=(C4H204) 58-0 FormicJF = (C2HO3) 37-0 Gallic,"G= (C7 HO3) 67-0 Hydriodic, HI 127-6 Hydrobromic, H Br 79-4 Hydrochloric, H CI 36-5 Hydrocyanic, H Cy 27-4 Hydrofluoric, H Fl 19-7 Hydrosulphuric, H S 17-0 Hypermanganic, Mn2 O7 112-0 Hyposulphuric, O5 72-3 Hj'posulphurous, 83 O2 48-3 Iodic, I O5 166-6 Lactic,T"= (C6H5O5) 81-0 Malic, M'= (C8H4O8) 116-0 Manganic, Mn O 3 51-7 Nitric, N O5 54-0 Do hydrated, H O, N Ojj 63-0 Oxalic, C2 O3 36-0 Phosphoric, P O5 71-5 Silicic, Si 0 3 46-3 Sulphuric, S O3 40-1 Do hydrated, H O, S O3 49-1 2(H 0,803) 98-2 Sulphurous, SO2 32-1 Tannic, Tn = (CI8H5O9) 285-0 Tartaric, Tar= (C8H4O16) 132-0 11. BASES. Alumina, AI2 O3 51-5 Ammonia, NH3 17.0 Antimony, oxide of 153-0 Barytas, Ba 0 76-7 Chromium, oxide of, Cr2 03 102-4 Cobalt, oxide of, Co O 37-6 Copper, protoxide of, Cu O . ... 39-7 Copper, suboxide of, Cu2 0 71-4 Iron, peroxide of, Fe2 O3 78-4 Iron, protoxide of, Fe 0 35-2 Lead, protoxide of, Pb 0 111-7 Lime, CaO 28-5 Magnesia, MgO 20-7 Manganese, protoxide of, Mn 0 37-7 Mercury, oxide of, Hg O . 109-4 Mercury, suboxide of, Hgo 0 . . . 210-9 Nickel, oxide of, Ni 0 37-6 Platinum, oxide of, Pt 0 106-8 Potash, K O 47-3 Silver, oxide of, Ag 0 116-3 Soda, NaO 31-3 Strontian, Sr 0 51-9 Tin, peroxide of, Sn O2 74-9 Tin, protoxide of, Sn O 66-9 Zinc, oxide of, Zn 0 40-3 HISTORY OF GAS ILLUMINATION. 15 GAS ILLUMINATION. .2 J< CO „ eS i>> p. ^ -S a •2 .a V ■-' rt 'i S ^ «5 3 « a> — o M d u S o 2 " '3 S 2 o 5 M a v .2 -a 4 5P .S 5 5 r, p. «rt 02 3 C -BO o. a -a eS eS >3 C !> r^ O , o « S .« ° ° i> bo a a; Qj o/) o o 60 0) 133 28 GAS ILLUMINATION. (J Fig. 4. The quality of the gas depends in no small degree on the shape and size of the retort. The original form was that of a cylinder placed upright (fig. 2), large enough to hold about fifteen pounds of coal, with the exit-tube at top by Fig°2. Fig. 3. the side. Such a retort is very readily charged, and the gas produced from it is of good quality ; but its form is very incon- venient for the removal of the coke at the end of the process. One of the means devised in order to remedy this defect Avas to have an opening at the bottom of the retort (fig. 3) at which the coke might be easily withdrawn, the coal being introduced at top, as before ; but the trouble of closing both of the aper- tures at each charge was found to be as great as the removal of the coke in the original form. A much larger retort, of the original form, was afterward used, capable of holding from ten to fifteen hundred weight of coal, from which the coke was easily removed by an iron basket or grappler (fig. 4), suspended by chains, and put into the retorts before the charge of coal. At the end of the process, the grappler with the coke was removed by a crane. The great disadvantage of this retort is, that the heat re- quires a considerable time to penetrate to the interior of the great mass of coal, the cake of coke formed at the side of the retort being a very badly conducting medium, and gas produced slowly is far inferior in illuminating power to that formed quickly, as in the original small retort, for reasons which will afterward appear. To the latter it vvas found expedient to return and the inconvenience experienced in -.c®i;i>tgas^ the removal of the coke was lessened by placing the retort in a horizontal position ; the coal is usually introduced by a common square spade, and sometimes by a tray of sheet-iron, similar to a grocer's scoop, which is pushed to the end of the retort, inverted so as to turn out the coal, and withdrawn. , , • ■ ^ The forms of the retort generally used at present are shown m vertical sec- tions, parallel to the door, at figs. 5, 6, and 7 ; fig. 5 is called the D or semi- circular retort, fig. 6 the kidney-shaped retort, and fig. 7 the elliptical retort. The greatest breadth of each form is about twenty or twenty-two inches, and the height in the middle from nine to twelve inches. The kidney-shaped retort is said to require the least heat, and to yield the largest quantity of good gas in. the shortest time; the circular or cylindrical retort is seldom employed in well-conducted gas-works, unless its diameter is made less than twelve or fourteen inches.* The length of the retort is commonly seven feet six inches. Cast-iron is the only material used for gas retorts in this country, but in some parts of the Continent baked clay is emploved. The ordinary duration of a retort charged four times in twenty- four hours is three months. The door of the retort is secured by a cross-bar and Fig. 5. Pig 7. Fig. 8. hold-fast screw, as shown in fig. 8, and rendered air-tight by a luting, for which purpose the re- fuse lime from the purifier is found convenient. Three, five, or seven retorts are arranged in one furnace or " bed," according to the extent of the works. Each retort has what is called a mouth-piece a, fig. 8, projecting from the front of the brickwork, from which rises the upright tube leading into the hydraulic main. The diameter of this tube is three or four inches, its height to the bend from ten to fourteen feet, and the distance of the hydrau- lic main from the bend from three to four * The circular retort of ten or eleven inches in diameter is preferred at the Manchester gas- works, where cannel coal only is employed. c PROCESS OF MAKING COAL-GAS. 29 feet. The bend is commonly made by a plain curve, but sometimes by a saddle joint, as in fig. 8. As the extremity of each tube from the retorts dips under the liquor in the hydraulic main, all direct communication between the gas in the latter and that in the retort is cut off, so that either of the retorts may be emptied and discharged while the others are being worked, without interfering with the process. The height of the exit-tube above the hydraulic main must be suf- ficient to prevent the liquor being driven into the retort by the pressure on the gas in the lime purifier g, fig. 1, page 26. In extensive gas works there are from four to six hundred retorts, of which from two to three hundred are worked on the average of summer and winter, each retort being charged with about a hundred and twenty pounds of coal every six hours. The retort furnaces are arranged in rows, generally on each side of the retort house, the flues from the diflferent furnaces meeting in a* central chimney. As coke is the fuel generally employed to heat the retorts, little or no smoke is given olf. In a well-conducted establishment, two men are suflScient for the management of three furnaces of five retorts each ; but, as the retorts are kept m constant work throughout the twenty-four hours, relays of men are required for the night-work. By the decomposition of the olefiant gas and vapors of hydrocarbons at a high temperature (page 23), the interior of the retorts becomes lined with a dense carbonaceous deposite, which, by its imperfect conducting power, offers an impediment to the transmission of heat. A patent was obtained in 1837, by Mr. Kirkham, engineer, for a mode of removing the incrustation by means of a jet of heated atmospheric air, which is impelled with force into the interior of the retort, maintained at a red heat during the operation. The air is conveyed by means of an iron pipe with flexible joints proceeding from a blowing ma- chine, and bent so as to allow the nozzle, at its extremity, to be directed to any point on the surface of the interior of the retort. The tube which conducts the tar and ammoniacal liquor to the cistern d, usually proceeds from the end of the hydraulic main, a little above the middle, so as to leave the latter always half full, or nearly so, of liquor. The tar and ammoniacal liquor are not miscible; and the former, being the heaviest, is found at the bottom of the cistern, whence it may be withdrawn by the cock i. Although a very large quantity of tar and ammoniacal liquor is deposited in the hydraulic main, yet the gas, in consequence of its high temperature, retains a considerable amount of these bodies in the state of vapor, which must be re- moved before it enters the lime purifier. To effect their separation, the tem- perature of the gas is reduced by passing it through the cooler or condenser (/. fig- 1). Fig. 9. Fig. 10. Tr cz^'cz^ €=3 cr f% /r% f% M ^ %^ %J) \i) Figs. 9 and 10 represent a convenient and eflTective condenser, which was in- vented by Mr. John Perks, in 1817. It consists of a series of four-inch tubes, ar- ranged in a rectangular iron chest, double-bottomed and open at top. The di- mensions of the tank for a moderate-sized establishment may be ten feet in height, six feet six inches in length, and six feet in breadth. The bottoms of 30 GAS ILLUMINATION. the tubes are open, and terminate ia the plate a, between which and the true bottom are placed partitions, to separate ihe extremity b from the extremity c, h' from c', b" from c", &c. ; but these partitions do not quite extend to the true bottom. The tubes are severally connected at top, either by a curved tube or a saddle-joiat, so as to form, with the partitions at bottom, one continuous tube. The appearance of the top of the tank is shown in fig. 10. A tank of the above dimensions may contain forty-eight upright tubes, each eight feet six inches in length, making, with the bends at top and communications at bottom, a continuous°tub'e of a length of 432 feet. Cold water is poured into the cooler by the funnel-tube d, the heated water passing off by the pipe e. The tar and ammoniacal liquor fall into the space /, from which they are withdrawn by the tube s, and conducted, in some gas-works, into the tar cistern. Sometimes, instead of enclosing the tubes in a cistern of water, they are made somewhat longer, and cooled bv mere exposure to the air. The condenser represented in fig. 1, page 26, is of a different construction from that just described, and not so generally adopted as the latter. This form, which was proposed by Mr. Malam, and is reported to be satisfactory in its op- erations, consists of an iron rectangular vessel about nine feet long, five feet wide, and four feet deep, containing several horizontal partitions or shelves of cast-iron plates, which have edges of about three inches in height, for the pur- pose of holding water. These shelves are all fastened to the sides, and, alter- nately, to one end of the tank, a space of about six inches remaining between the other end of the shelf and the tank. Water is first poured in through an opening at top, and when the first shelf is full, the water flows over into the second shelf, and so on until all are filled. The excess of water flows out by the pipe t. The gas enters the box at u, and passing over successive sheets of water, equal to the area of each shelf, becomes thoroughly cooled, and passes out at's. The condensed matters flow out by the pipe t. From the cooler the gas is next conducted to the lime purifier fig. 1, where it is freed from carbonic acid, sulphuretted hydrogen, hydrocyanic acid (or cyan- ogen), and some ammonia. (See table, page 27.) The separation of the sulphuretted hydrogen is the most important object in all the purifying operations. This gas not only affords no light on combustion, but diffuses an intolerable odor if it escapes into the atmosphere unburned, is highly poisonous, and produces by its combustion sulphurous acid, which, by the action of the oxygen of the air and moisture, passes into the state of sul- phuric acid, or oil of vitriol. The complete removal of sulphuretted hydrogen comes, therefore, to be a matter of no small importance. The only manner of effecting its separation is by the action of some substance for Avhich it has a chemical affinity, but which is without action on the pure gas. A substance of this kind is lime, which was suggested as a purifier by Dr. Henry, of Manches- ter, in 1808, but was not used generally on the large scale until several years afterward. Lime not only absorbs sulphuretted hydrogen, but also carbonic acid, and a little hydrocyanic acid, forming, respectively, sulphuret of calcium (hydrosul- phate of lime), carbonate of lime, and cyanide of calcium. The principal methods employed to get rid of sulphuretted hydrogen, previous to the intro- duction of lime, were, passing the gas through' hot iron pipes and through a large quantity of water; but such methods are quite ineffectual. Lime may be applied to the gas in two ways : 1st, mixed up with water to about the consistence of thin cream (in the "wet-lime purifier"); and 2dly, as slaked lime slightly moistened with water (in the " dry-lime purifier"). The former method is most commonly practised. The wet-lime purifier represented at fig. 1, is a round cistern, into which the gas is conducted by the pipe k ; this pipe is greatly expanded at its ex- tremity into a cone and flat disc, and the latter is pierced with a great num- ber of very small apertures : / is a rouser or agitator, to stir up the lime at the bottom of the purifier; it consists of an upright shaft, with a wooden or iron framework at bottom. The shaft of the rouser passes through a stuf- fing-box at the top of the purifier, and is turned by wheel and pinion work. In PROCESS OF MAKING GAS. 31 large gas-works the rouser is kept in motion by a steam-engine, which is also used for lifting coals, pumping up water, and other heavy work ; but in small gas-works the rouser is worked by the hand. The milk of lime is made with one part of slaked lime to about twenty-five parts of water: it is introduced by the tube p, and v.'ithdrawn by the opening r, four times in twenty-four hours. The height of the liquid above the disc is usually about ten inches. In small gas-works o'aly one lime purifier is used at a time ; but in larger establishments the gas is passed through two, and sometimes three purifiers successively. In some of the London gas-works the gas is passed through three or four purifiers at different elevations ; the second stands at a higher level than the first, and the third higher than the second. By this arrangement the lime is made to enter and leave the purifiers in an uninterrupted current: the highest purifier, which is also the last through which the gas is passed, receives the milk of lime from a cistern placed above it, and, as the liquid attains a certain height, it is conducted by a discharge-tube, or waste-pipe, into the second puri- fier on a lower level, whence the liquid is conducted into the first purifier. From the latter it is let off by an exit-pipe. As the gas travels in the opposite direction to the lime liquor, it is brought gradually into contact with purer lime ; in the first vessel it meets liquor which has already purified other por- tions of gas in the vessels above ; in the second vessel it meets a purer liquor ; and, almost purified itself, passes thence into the third vessel, where it meets lime fresh from the cistern above. A more effectual method of obtain- ing the complete absorption of the condensable gases could hardly be devised. When the gas is arrived at the last purifier, to ascertain if all the suphu- retted hydrogen is absorbed, it is tested by carbonate or acetate of lead, which, like all other salts of lead, have the property of becoming brown or black when put into contact with sulphuretted hydrogen, the sulphuret of lead being formed. These tests are commonly applied by allowing a jet of the gas to escape, by opening a stop-cock fixed for the purpose to the cover of the purifier, and holding against the jet a card smeared with the carbonate or moistened with a solution of the acetate or subacetate of lead. If sulphuretted hydrogen remains, to the amount of no more than the thirty-thousandth part of the bulk of the gas, it may be easily detected by the coloration of the card. It is neces- sary that the card should be moist in ibis experiment, as some salts of lead thoroughly dry are not affected by sulphuretted hydrogen gas, if the latter is also perfectly dry. Another way of applying the lead test is, by attaching to the cover of the purifier one end of a bent tube, provided with a stop-cock, the other end of which is made to dip into a vessel containing an aqueous solu- tion of acetate or subacetate of lead. If the gas is pure, it is commonly next conducted by the pipe m, to the gasometer h. In the process of purifying the gas by slaked lime, merely moistened, in the " dry-lime purifier," patented by Mr. Reuben PhiUips, of Exeter, the gas is in- troduced at the bottom of a rectangular iron vessel (of the dimensions for five hundred lights, of five feet in length, five feet in breadth, and three feet in depth), and passed upward through several layers of lime, placed on iron ora- tings or on perforated shelves of cast-iron, about seven or eight inches apart. The perforations are three eighths of an inch in diameter, and three quarters of an inch distant from centre to centre. The gas is conducted by a pipe from the top of the purifier to the gas-holder. Fresh slaked lime, moistened, but not sufficiently to be adherent to the hand, is placed on each shelf to the depth of three or four inches, and is then wetted with about a gallon of water from a watering-pot with a rose. The top of the tank is moveable, and fits into a wa- ter-joint, or trough, ten inches deep and six inches broad. The shelves are also moveable, so that the upper ones may be removed while the lower are being charged. This form of purifier is found very convenient in small works, but is too bulky when adapted to large establishments. Mr. Malam, however, pa- tented, in 1822, an effective purifier for the use of extensive gas-works, on the sarno principle, but more complicated. This method is said to require nearly twice as much lime as the wet purifier, without the purity of the gas being in- 32 GAS ILLUMINATION. creased; but it has a great advantage in requiring no constant mechanical power. In the wet purifier a bushel of lime is sufficient to purify, on the aver- age, about twelve thousand cubic feel of gas. The spoiled and foetid lime was formerly allowed to run to waste, to the great annoyance of the neighborhood ; it is now preserved and employed as manure, and also as a cement to luie the covers of the retorts. The foetid li- quor which is dramed from the lime obtained in the wet-lime purifier, is thrown into the ash-pits of the furnaces, where it evaporates, its vapor passing through the fire and up the chimney. By keeping the bars of the furnace cool, the va- por tends materially to their preservation. The gasometer, h, fig. 1, consists essentially of two parts : a round cistern, open at top, and filled with water; and the gas-holder, which is a cylindrical vessel, open at bottom and closed at top, very little smaller in diameter than the cistern within which it floats. The size of the gasometer varies from thirty to fifty feet in diameter, accor- ding to the extent of the works. It is considered that a capacity of thirty thousand cubic feet is the largest dimensions which can be given to the gas- ometer with advantage, as the sheet-iron of which it is formed must then be inconveniently thick, and very strong internal cross-bars would be required to strengthen the hollow cylinder. The cistern, or exterior tank, is commonly made of plates of cast-iron, but sometimes of masonry, made tight with hy- draulic mortar. In some gas-works the whole cistern is sunk in the ground. The gas-holder may be supported Avithm the cistern by means of a chain n, cormected with rods, which are attached to the top of the gas-holder : the chain runs over two pulleys, o and 6, and bears a comiterpoise j>, to the gas-holder, which leaves the latter to exert only as much pressure as is necessary for the proper expulsion of the gas. Large gas-holders are usually suspended by three or more points at their circumference. The tuhe which conducts the gas from the lime purifier to the gasometer and the tube q, which is to distribute the gas to the street-pipes, terminate a little above the water in the cistern. Nothing can be simpler than the action of this gasometer. When the gas is to be collected, the gas-holder is sunk deep in the cistern so as to be full of water. As the gas is emitted by the tube m, the weight p being about equal to that of the gas-holder, the latter rises, and at length reaches the top ; but, its edge being under water, the gas within has no communication with the external air. To expel the gas, the weight of p may be reduced a little, so as to increase the pressure of the gas-holder ; the tube y being open, the gas will be driven out, and the gas-holder become again filled with water ready to receive a fresh supply of gas. There are several gasometers in large works, some being filled while others are being emptied.* According to the hydrostatic law, that dm weight of a body in water is less than its weight in air by the weight of the water which it displaces, it is ob- vious that the weight of the gas-holder decreases as it sinks in the cistern, according to the weight of the Avater displaced by the submerged sides of the gas-holder. To obviate any inconveniences arising from this inequality of pressure, the weight of the chain n is so adjusted as to compensate for the loss in the weight of the gas-holder by immersion, the length of chain which passes the pulley o being made equal to one half of the loss; the other half is compensated by the same weight of chain passing the other pulley, to add to the weight of the counterpoise. But as the coal-gas within is considerably lighter than the air without, and, moreover, varies in density according to the manner in which it is prepared, the exact diminution in the weight of the gas-holder is not easily determined by calculation. The inconveniences which attend the bulkiness of the ordinary gasometer have led to different contrivances by which a greater bulk of gas may be col- lected over the same area of ground. The most successful of these is the telescope gasometer, fig. 11, the gas-holder of which consists of two, three, or more cylinders of unequal diameter, and concentric. The bottoms and tops of * At the Westminster station of the Chartered Gas Company there are no less than twenty-one fasometers, each containing on the average thirty thousand cubic feet. PROCESS OF MAKING GAS. 33 the cylinders are provided with flanges curved in op- posite directions, the flange turning inward and up- ward at bottom, and outward and downward at top. The outermost cylinder is covered at top, but all the others are open both at top and bottom. Supposing the cylinders to be sunk in the cistern and ready to receive gas, the outermost first rises on the admission of gas, and, when its bottom reaches nearly to the surface of the water, its curved flange catches the flange of ' the next cylinder, which then rises, and in like manner lifts the next. It will be perceived that the two rims form together a water-lute which prevents the egress of gas and the ingress of air. This gasometer is sometimes constructed in such a manner that the innermost cylinder (which is then the covered one) rises first, and the outermost last ; the= ■ — curves are then made in the opposite directions, but the nrincinlp nf the onn STat thr''"'^\^ '''' • TJ^e telescope gasoSTafe^^Lursus: 'Xys I^:^^^^^^^ --/over 7™erous substances given off from coal when that body is subjected to the destructive distillation (mentioned in the table at page 27), are not afforded in the same relative proportions at the same periods of the distillation On the first application of heat to coals in a retort, steam comes off, tocretS with the air of the retort. As the heat approaches redness, a con^derable quantity of tar is disengaged, but only a small proportion of gas below a red heat ; and what gas is produced at that temperature possessess ver^feeWe illuminating power. When the retort has attained a bright red heat the evolution of gas is at its maximum ; but tar is still produced, though in srn'alle? quantity than at a lower temperature. At a tvhite beat, and after the opeTation has been earned on for two hours, the proportion of tar is very small tS of the gas IS still large, but decreasing. At length the evolutioh of gas ceases completely, whatever degree of heat is applierL ^ The difference in the bulk of the gas given off from coal at different periods of the process is shown m the following taMe, by Mr. Peckston of th p obtamed from a chaldron of Newcastle co«l distributed fnto Sg&el retofts The coal was heated to bright redness immediately. retorts. In the first hour ^""^'L-t^' In the second hour 2000 In the third hour J^^^ In the fourth hour * fg^' In the fifth hour t^/J. In the sixth hour '.V, In the seventh hour In the eighth hour 775 In eight hours The composition and iUuminating power of the gas produced at different periods of the process vary considerably. The gas evoked reforfthe reto? attains a red heat contams a considerable amount of carbonic oxide • hence hs eeble lUummatmg power. That produced at a bright red heat conSs f ll^'yjT'Tf'^'^^''' "^'^ vaporsof hydfocarbonrtharwhat is formed at any higher or lower temperature. As the distillation advances thp emperature being somewhat increased, the proportion of illumin^^^^^^ decreases considerably, while that of carbonic oxide and hySgen £fS m proportion. The density of the gas also, which is to a certair^Ttp?.f^rf portxonal to its illuminating power,Vaduaily decreases ^ith the duration' 0/ 34 GAS ILLUMINATION. the process and the increase of the temperature. The following tabular vie-w of results of the examination, by Dr. Henry, of the gas evolved from cannel coal at different periods of the process, will show more clearly the difference in the composition. COMPOSITION OF COAL-GAS IN 100 VOLUMES. 1. 2. 3. 4. 5. Olefiant gas and vapors of hydrocarbons 13 12 12 7 0 Light carburetted hydrogen 82-5 72 58 56 20 Carbonic oxide 3-2 1-9 12-3 11 10 Hydrogen gas 0 8-8 16 21-3 60 Nitrogen gas 1-3 5-3 1-7 . 4-7 10 100-0 100-0 100-0 100-0 100 Density of original gas (air as 1000) 650 620 630 500 345 Measures of oxygen required for combustion of 100 measures of gas 217 194 196 166 78 Measures of carbonic acid produced 128 106 108 93 30 Density of gas remaining after agitation with chlorine 575 527 533 450 345 Nos. 1, 2, and 3, of the preceding table were produced during the first hour of the distillation, No. 4 at the commencement of the sixth hour, and No. 5 ten hours after the commencement. Some of the rules for the production of good coal-gas may be deduced from the preceding observations. In the first place, to reduce the product of tar as much as possible, the coal should be rapidly heated to bright redness ; the retort, in fact, should always be at a bright red heat when the coal is intro- duced ; a portion of the tar, which would otherwise distil over into the hydraulic main, is thereby converted into excellent gas. For the same reason, the coals should not be introduced into the retort in large masses. In that case, an exterior coating of coke is soon formed, which retards, by its non- conducting power, the transmission of heat to the interior (rf the mass. The advantage in the use of the D-ghaped, kidney-shaped, and elliptical retorts, over the circular or cylindrical (^age 28), is wholly referable to the circum- stance, that the coal is more rapivjly heated in the former than in the latter, from the exposure of a greater surface to the heat. The average quantity of gas obtained from a ton of Newcastle coal in the D-shaped, kidney -shaped, or elliptical retort, is 9,000 cubic feet in the circular retort, the diameter of which is about the same as the widestdiameter of the other construction, the average quantity from the same kind of coal, at the same degree of heat, and worked in the same manner, is 6,400 feet. According to the experiments of Mr. Peckston, the charge in elliptical, kidney-formed, or D-shaped retorts, may be worked off in half the time require^! with circular retorts. Five of the former, worked with 120 pounds of coal to each, during a four-hours' charge, will produce, in twenty-four hours, as xnuch gas as ten cylindrical re- torts, worked at eight-hour charges with 160 pounds of coal to each retort every charge. (Peckston, Practical Treatise on Gas-lighting, p. 126, 3d edit.) The form of retort said to behest adapted for the rapid decomposition of the coal is the " rotary retort," patented by Mr. Clegg in 1816, but its expensive- ness has hitherto proved an obstacle to its general introduction. In consists essentially of a large rectangular iron box, containing fifteen little boxes, each charged with about fifty pounds of coal. Only a portion of the large box is heated to redness, the temperature of the remainder being insufficient to cause the decomposition of coal. The small boxes remain for four hours in the cooler part of the large box, during which time the coal becomes thoroughly dried ; they are then (by five at a time) for two hours at the part heated to redness. The gas obtained from the rotary retort is of excellent quality, and a ton of common coals is said to afford 11,400 cubic feet. Twenty-seven hundred-weight of coals may be worked off in twenty-four hours. PROCESS OF MAKING COAL-GAS. 35 Curing the whole process, the temperature of the retort should not exceed that of a bright red heat. At a higher temperature, the proportion of hydro- gen, carbonic oxide, and nitrogen gases, is greatly increased ; while the pro- duction of olefiant gas, the chief illuminating ingredient, almost ceases. This arises from the decomposition of the olefiant gas at a- high temperature into free hydrogen or light carburetted hydrogen and carbon ; the latter is depos- ited m a solid state around the sides of the retort in a peculiar form, known as gas-carbon. The carbonic oxide gas (CO or CgO^) is derived from the conabination of carbonic acid gas (COj) with carbon ; one equivalent of car- bonic acid giving rise to two equivalents of carbonic oxide, by uniting with one of ca.rbon. The nitrogen is probably derived immediately from the de- composition of ammonia into its elementary constituents, hydrogen and nitro- gen. If both the carbonic acid and ammonia had remained as such, instead of being converted into carbonic oxide, nitrogen, and hydrogen, they might have been readily separated in the process of purification ; but no efficacious and simple means are known of removing the above products of their decom- position. Hence the disadvantages of increasing the temperature beyond that of bright redness. As nitrogen and carbonic acid oxide gases are always dis- engaged in abundance at the end, in the ordinary manner of conducting the process, if gas of a very superior quality is required, the operation should be stopped two hours after the commencement. But the quality and quantity of the gas depend, as might be supposed, on the quality of the coal, as well as on the manner of conducting the distilla- tion. The selection of a proper kind of coal for making gas is a subject which seems to deserve more attention from the managers of gas-works than it com- monly receives. It is probable that in the end there would be a considerable saving, even in the London gas-works, by the adoption of richer kinds of coal than those commonly employed, as cannel coal, for instance, which would generate a more highly carburetted gas, and give as brilliant a light in smaller quantity, without the production of so much heat as is developed in the combus- tion of the highly hydrogenated gas derived from the commoner kinds of coal. In such case, the price of the gas per meter might reasonably be increased. Less labor and a smaller capital, too, are required to work a rich than a poor coal, as the apparatus for the former need not be on so extensive a scale as for the latter. The following table shows the quantity of gas obtained on the large scale from several diiferent kinds of coal in elliptical retorts at a bright cherry-red heat by daylight, the charge to each retort being about 126 pounds of coal :— Names 0/ Corns. Scotch Cannel Lancashire Ciinnel Yorks.'iire raiinel Bew/cke and Craister's Wallsend Rujsell'5 Wallsend Pewicke's Wallsend Tanfield Moor Bell's Wallsend Forest of Dean (High Delph) . . . Heaton Main Hartley's Cowper's High Main Killingworth Main Benton Main Pontops , Wigan Ovall Wear Wallsend Burdon Main Brown's Wallsend Wellington Main Cubic Feet of Gas obtained from one Ton of Coals. 11,850 11,680 11,240 10,370 • 10,360 10,131 10,070 9,963 9,880 9,740 9,600 9,460 9,393 9,082 9,0^^0 9,000 8,652 ...... . 8,341 8,336 8,270 36 GAS ILLUMINATION. Names of Coals. Temple Main Headsworth Hebburn Seam Hulton Seam . . .*. Nesham Manor Wallsend Forest of Dean (Low Delph) . . Bleyth Forest of Dean (Middle Delph) Eden Main Straffordshire Coal, first kind . . Primrose Main Staifordshire, second kind Do. third kind Do. fourth kind Pembry The results in the preceding tahle were the fruit of a series of carqful and laborious experiments by Mr. Peckston, the greater part of which were performed on an extensive scale, and all sufficiently large for obtaining results of great practical value. {Practical Treatise on Gas-lighting.) _ In the process of puiification by lime,' to which the gas is subjected in order to deprive it of sulphuretted hydrogen and carbonic acid, the illuminating power of the gas appears to be reduced to a consideraljle extent ; hence the advantage of selecting such kinds of coal as contain least iron py- rites. The reduction in illuminating power, where extensive purification is required, is shown in the results of some experiments by Dr. lire, who found, in a specimen of coal-ga?, as delivered from the retorts of one of the metropolitan companies, no less than 18 per cent, of olefiant gas, or of the vapors of hydro-carbons and oleft^nl gas ; but, after having been passed through the purifiers, there remained only 11 per cent. Mr. John Dayies, of Manchester, estimates that 10 per cem, more of light might be realized by making use of a coal nearly free from sulphiir, in the place of the common coal containing pyrites. (Meeting of Brit. AssDciaiion, 1842.) There is rea- son to believe, however, that this estimate is too high for general application. M. Penot has called the attention of the manager? of gas-works to the great advantage which would result by the employment of coal previously deprived of its hygrometric moisture by drying. In its ordinary state, coal, according to M. Penot, contains 10 per cent, of hygrometric Water. When steam comes into contact with olefiant gas and the vapors of hydrocarbons at a red heat, mutual decomposition takes place, with the productitn of carbonic acid for carbonic oxide) and hydrogen or light carburetted hydrogen. The loss of the luminiferous constituents of the gas from this cause seems to be very consid- erable, but may be prevented to a great extent by making Mse of coal previ- ously dried. It is stated that the quantity of olefiant gas produced from coal containing its ordinary proportion of hygrometric moisture, is to that pro- duced iTrom the same coal in a dry state as 1 : 1-5. One kilogramme of coal, containing 10 per cent, of water, afforded 160 litres of gas of good quality, giving a white flame, 92 litres of inferior gas, giving a red flame, 252 leaving 632 kilogrammes of coke. One kilogramme of coal, previously well dried, afforded 240 litres of good gas, 92 litres of inferior gas, 332 leaving 668 kilogrammes of coke. Cvhic Feet of Gas obtained from wie Ton of Coals. 8,180 8,052 7,896 7,785 7,763 7,700 , 7,660 7,420 7,260 6,670 6,474 6,220 6,090 5,840 5,807 4,200 PROCESS OF MAKING COAL-GAS. 37 The difFerence is certainly far greater than might have been anticipated, but the exactitude of the proportions determined by M. Penot has been con- firmed by experiments made on an extensive scale at the Mulhausen gas- works by a committee appointed by the Societe Industrielle of Mulhausen. M. Penot's paper on this subject may be found in , the Journal fur prakhschen Chemie, xxiv., 106, and the report of the committee in the Bulletin of the society. The presence of ammonia in coal-gas, after having been subjected to ihe or- dinary processes of purification, seems to have escaped notice until lately. A considerable quantity of the sulphuretted hydrogen which enters the lime purifier is in a state of combination with ammonia, as hydrosulphate. This substance is decomposed by the lime in the purifier, with formation of sulphu- ret of calcium and evolution of free ammonia. Carbonate of ammonia also enters the lime purifier in the state of vapor, and is decomposed by the lime in a similar manner, with production of carbonate of lime and free ammonia. A small proportion of the ammonia formed by these sources remains dissolved in the water of the purifier ; but the greater part comes off as gas, mixed with coal-gas. This impurity is not very injurious to the illuminating power of the coal-gas, and, if the gas is kept in the gasometer for a short time, the water abstracts it almost entirely ; but several processes have been proposed for the removal of the ammonia before the gas enters the gasometer. The process patented by Mr. Phillips, of Exeter, consists in conducting the gas from the lime purifier into a tank containing a solution of alum. In order to expose a large surface of the purifying liquid to the gas, a quantity of broom is im- mersed m the solution. In the course of a few hours the bottom of the puri- her becomes covered with a quantity of alumina, produced through the de- composition of the alum. The sulphate of alumina contained in the alum produces, with free ammonia, sulphate of ammonia, which remains in solu- tion, and alumina, which is precipitated. _ A solution of protosulphate of iron (gyeen vitriol) was substituted for alum m the above process with a corresponding result, oxide of iron bemg precipi- tated, and sulphate of ammonia formed in the solution ; but green vitriol pre- sents advantages which are not possessed by alum. Hydrosulphate of ammo- nia and hydrocyanic acid, traces of which sometimes escape the action of the lime in the purifier, are imperfectly absorbed bv a solution of alum : the latter absorbs only the ammonia of the hydrosulphate ; the sulphuretted hydrogen passes on to the gasometer. But green vitriol absorbs hydrosulphate of am- monia as well as free ammonia, producing in the former case sulphuret of iron and sulphate of ammonia, instead of oxide of iron and sulphate of ammonia, as happens Avith free ammonia only. The hydrocyanic acid, or, more prop- erly, hydrocyanate of ammonia, is likewise absorbed by green vitriol, with the production of a variety of Prussian blue. Mr. Lowe, of the Chartered Gas Company's works, proposed to separate the ammonia by passing the gas through dilute sulphuric acid, after having passed the lime purifier. As concentrated sulphuric acid (oil of vitriol) rap- idly absorbs the vapors of the oily hydrocarbons, and also olefiant gas, it can not be used for this purpose ; but, when the dilute acid has been so long in use as to be saturated with ammonia, a small quantity of oil of vitriol may be ^"troduced by a funnel-tube, fitted to the purifying vessel for that purpose. When It is required to separate the ammonia on the small scale, as by the consumer himself, the gas may be exposed to the dilute acid in Mr. Lowe's naphthalising box with perforated shelves, a description of which may be lound in another part of the present article. Anothe ' method of separating the ammonia was proposed by M. Blondeau de Carolles, which consists in conducting the gas from the lime purifier through a vessel containing layers of coke covered with chloride of calcium, a sub- stance which rapidly absorbs ammonia. V^^^^^*^ °^ these purifying agents is much employed at present, as it is tound that the ammonia may be very easily and completely separated by merely washing the gas with water. The most effectual method of washing the gas 38 GAS ILLUMINATION. is to conduct it from the purifier to the bottom of a tank containing broom- twigs, water being introduced at the top and allowed to trickle slowly over the broom. The ordinary wet-lime purifier {g, fig. 1) may also be used for the same purpose. The solution of ammonia which is thus obtained is em- ployed in the manufacture of sal-ammoniac and sulphate of ammonia. Mr. Mallet has proposed to transmit the gas, as it comes from the condenser, through two purifiers, containing solutions of green vitriol or solutions of sul- phate of manganese,* and afterward through the milk of lime. The sulphate of ammonia thus obtained would not only cover the expense of the green vit- riol, or sulphate of manganese, but give a clear profit. It is said that very little sulphuretted hydrogen remains to be absorbed by the milk of lime, and that the gas thus purified does not produce a trace of sulphurous acid in its combustion. An incidental advantage attending this method is, that much less labor is required to keep the lime in a state of agitation. In 1841 a patent was granted to Mr. Croll, superintendent of the Erick Lane gas-works, for the use of a solution of chloride of manganese, dilute sulphuric acid, and dilute muri- atic acid, for a similar purpose : the gas is afterward passed through the lime purifier. . . , , i Sulphate of lead, which is a by-product in calico print-works, has been pro- posed by M. Penot as a purifying agent in districts where it may be procured at a very cheap rate. It absorbs hydrosulphate of ammonia completely, the oxide of lead retaining sulphuretted hydrogen, and the sulphuric acid ammo- nia. In no part of this country, hoAvever, can sulphate of lead be procured sufficiently cheap for such an application. § V. SECONDARY PRODUCTS OF THE COAL-GAS MANUFACTURE. Next to the gas itself, the most important and valuable of the volatile prod- ucts of the distillation of coal is the ammoniacal liquor, or gas-water. This liquid and the tar are condensed, for the most part, in the hydraulic main h, fig. 1, whence they are conducted into the tar-cistern. A further quantity is also separated from the gas in the condenser. The tar is found at the bottom of the cistern, the ammoniacal liquor floating over it. The ammoniacal liquor of the coal-gas works is at present the principal source whence the commercial demand for sal-ammoniac and carbonate of ammonia is supplied. The average price of this liquor may be taken at half a crown per butt of 108 gallons. A ton of good coals affords rather more than two hundred pounds of ammoniacal liquor. This liquid is essentially an aqueous solution of hydrosulphate and carbonate of ammonia ; but it also contains muriate of ammonia, sometimes in consider- able quantity,! hydrocyanate of ammonia, acetate of ammonia,| gallate of ammonia (Mr. Leigh), and sulphite of ammonia. Muriate of ammonia is pre- pared from this source by saturation with muriatic acid, when sulphuretted hydrogen, carbonic acid, and a little hydrocyanic acid are given off, and an equivalent quantity of muriate of ammonia remains in solution. By evapora- tion to dryness and sublimation, this salt is obtained nearly pure. Sulphate . of ammonia is prepared in very considerable quantity from ammoniacal liquor ; not to be used itself, but to be afterward converted into carbonate of ammonia (smelling-salts). The sulphate is made either by saturating the liquor with sulphuric acid, or by the addition of green vitriol, procured by the oxidation of iron pyrites. In the latter case, sulphuret and carbonate of iron are first formed and precipitated, being insoluble compounds. Sulphaite of ammonia remains in solution, and is obtained by evaporation and crystallization. At the Dept- ford chemical works, which is one of the principal manufactories of ammonia- cal salts from gas-liquor in this country, there is a yea,rly consumption of be- tween five and six hundred thousand gallons of the liquor. A pipe is laid from * Sulphate of manganese is obtained as a by-product in the manufacture of bleaching-powder. + Four ounces of muriate of ammonia have been obtained from o.ne gallon of gas-water from cannel coal (Mr. Leigh.) t Acetate of ammonia is a constant product, according to Lampadims. SECONDARY PRODUCTS OF COAL-GAS MANUFACTURE. 30 the Deptford gas-works to the above establishment for the purpose of conveying the liquor. Of late years it has been proposed to make the hydrocyanate of ammonia con- tained in ^as-liquor available as a source of Prussian blue. The common method of preparmg- this pigment from gas-liquor is first to saturate the liquor with muriatic acid, and to add afterward a solution of green vitriol : but this method presents no economical advantages over the ordinary process. The proportion of tar obtained from coal in the process of making gas gen- erally amounts to about 8 per cent, of the coal. The disagreeable smell of this substance is an impediment to its extensive employment ; but it is used as a paint, to protect Avood, &c., from injury by moisture. When distilled, one hundred pounds of tar afford about twenty-six pounds of an oily liquid known as coal-oil ; the light product which first distils over is coal-naphtha. A black resinous substance, joj7cA, remains behind, of the chemical nature of which little is known : it is largely used for paying wooden piles, &c., which are to be im- mersed in water, and the bottoms of ships ; but it is not so well adapted for these purposes as pitch obtained from wood-tar ; it maybe procured, however, at a cheaper rate than the latter. Coal-naphtha is a mixture of several bodies, some of which are neutral, some possess the properties of an acid, and others those of a base. The most re- markable constituent is naphthalin, the properties of which, together with those of paranaphthalin, have already been described. Under the names of carbolic acid, rosolic acid, brunolic acid, pyrrol, leucol, and cyanol, M. Eunge has described some of the compounds said to be contained in coal-naphtha, but some of these bodies were probably products of the decomposition of the true ingredients. According to M. Dumas, benzin forms an ingredient of this com- plicated mixture, and M. Laurent believes a substance Avhich he has named the hydrate of phenyle to be an essential constituent. Coal-naphtha is a substance of considerable importance in the arts, it being one of the best and most, available solvents we possess for caoutchouc. It is also burned for the production of light in a peculiar kind of lamp, knoAvn as the naphtha-lamp, and is employed to impregnate coal-gas with its vapor, by which a considerable increase in the illuminatmg power of the gas is obtained. (The means of effecting the impregnation of coal-gas with the vapor of naphtha will be afterward described.) Tar may be viewed as an intermediate product in the conversion of coal into gas. It is given off from the coal at a comparatively lower temperature than gas, and is always the first product of the decomposition of coal. To reduce the product of tar, it was proposed by Mr. Parker, of Liverpool, to pass the gas, as it issues from the coal retorts, through iron lubes heated to Ijright redness, by which the quantity of gas would be greatly increaseu, and that of tar dimin- ished ; but the olefiant gas would become converted to light carburetted hydro- gen, with deposition of carbon, by long exposure to a bright red heat. The illuminating power of the gas would thereby be diminished, although the vol- ume of the gas would be increased. In some gas-works tar is made available as fuel for heating the retorts. About forty gallons are found to be sufficient for a ton of cannel coal. The coke which remains behind in the retort in the process of gas-making is not the least valuable of the secondary products. It consists of carbon to the amount of from 75 to 95 per cent., the remainder being the fixed saline and earthy matters of the coal. The proportion of coke formed generally amounts to about two bushels from a hundred weight of coal, or 60 per cent, on the original weight of the coal. Coke is always considerably lighter than the coal from which it is produced ; the bulk of the coke formed from those kmds of coal which are used for making gas in this country is generally 30 per cent, greater than that of the coal. In its physical aspect coke presents as many differences as exist in the varieties of coal from which it is produced. Some kinds of coal produce an infusible, and others a fusible coke, or rather a coke which fuses before it becomes fully carbonized. The coke from the former kinds of coal has the same shape as the original masses ; but the coals which 40 GAS ILLUMINATION. produce a fusible coke swell up considerably before becoming fully carbonized, the coke retaining the expanded form. Coals which produce an infusible coke, give, on destructive distillation, more water and less tar than the fusible coals. Coke is a reducing agent of great importance in certain metallurgic opera- tions, as it produces by its combustion a higher temperature than any other fuel, bulk for bulk. It is estimated in metallurgic works that one part of coke by volume will afford as high a temperature as two parts by volume of wood charcoal ; by weight, one part of the latter is considered equal to from one and a quarter to one and a half parts of the former. To produce a given effect, there is always consumed more of coke than of wood charcoal by weight, especially if a very elevated temperature is not required. The reason of this is that coke does not bum well, except in large masses, and with a powerful current of air, by which some of the heat is quickly dissipated. The earthy impurities contained in coke are a serious inconvenience in its employment in certain operations in metallurgy and the assaying of ores. § VI. OIL-GAS. In a few localities, where coal is difficult to procure, oil may be advanta- geously substituted as a source of gas. The oil employed for this purpose is the crudest and cheapest that can be prociyed; even pilchard dregs and the sediment of whale-oil, quite unfit for burning in the ordinary manner, are suf- ficiently pure for making gas. But oil is not at present used in the manufac- ture of gas on the large scale in any place where coal is accessible at a tnoderate price. The process of making oil-gas is much more simple than that of coal-gas, as the former requires far less purification. In one circumstance the two pro- cesses difl'er essentially. The oil is not introduced in quantity into the retort and heated for several hours, as coal is ; in such a case the greater part of the oil would distil over without Undergoing much alteration, and that portion only would be converted into combustible gas which is in immediate contact with the heated sides of the retort. What is required is the means of bring- ing a small quantity of the oil rapidly to a high temperature, even a red heat ; this is effectually attained by means of a simple apparatus invented by Messrs. J. and P. Taylor in 1815. The original apparatus consisted merely of a furnace with a contorted iron tube, containing fragments of brick or coke, into which, when red-hot, the oil was allowed to drop. When heated in this manner, oil is immediately decomposed, gases are given off, accompanied with a considerable quantity of vapors of substances which are liquid at common temperatures, and a large deposite of carbon takes place in the retort tube. An improvement has since been effected in the apparatus, which consists in conducting the exit-tube from the retort into an air-tight cistern, or receiver, in which the more easily-condensed products are collected in the liquid state Fig. 12. and returned to the retort. The gas proceeds from a pipe leading from the top of the cistern. In the annexed figure, a represents the retort, filled with pieces of coke about the size of a hen's egg ; b is the exit-tube, leading into the cistern c, from which the pipe d proceeds to the gasometer. The oil, melted fat, or distilled liquid of the cistern, is intro- duced into the retort by the tube e. The coke is changed every fortnight or three weeks, as the in- terstices become obstructed by the deposite of carbon. Oil-gas contains neither nitrogen nor sulphuret- ted hydrogen. It contains more carbonic oxide than coal-gas ; but the presence of that gas (which has hardly any illuminating power) is more tbaa OIL-GAS. 41 counterbalanced by the large relative proportion of olefiant gas, on which the illuminating power of both oil-gas and coal-gas essentially depends. From the presence of so much olefiant gas and vapors of hydrocarbons which are liquid at common temperatures, the illuminating power of oil-gas is reckoned at three times that of ordinary coal-gas, and twice that of the best coal-gas. The specific gravity of good oil-gas is 900; but it varies much, according to the temperature at which the gas is produced. The proper heat is that of dull redness ; if lower, the gas contains too large a proportion of the vapors, which, instead of being condensed in the cistern, are condensed gradually in the pipes and gasometer, occasioning not only a great loss of product, but no small inconvenience from the stoppage of the pipes. On the other hand, if the heat is above dull redness, the bulk of the gas is greater ; but its density and illuminating power are less, the olefiant gas being decomposed into car- hon and light carburetted hydrogen, as before explained. The following table by Dr. Henry exhibits the different qualities of gas produced from oil at dif- ferent temperatures : — COMPOSITION OF OIL-GAS IN 100 VOLUMES. No. 1. No. 2. No. 3. No. 4. 38 22-5 19 6 46-5 50-3 32-4 28-2 9-5 15-5 12-2 14-1 3 7-7 32-4 45-1 3 4 4 6-6 100 100 100 100 906 758 590 464 Volumes of oxygen required for com- 260 220 178 116 Volumes of carbonic acid produced . . 158 130 100 61 No. 1 was made from train-oil, in the ordinary manufacturing process, at a dull-red heat ; No. 2, at a higher temperature ; and Nos. 3 and 4, higher still. One gallon of whale-oil alFords on the average about 90 cubic feet of gas of the specific gravity of 900. A gallon of palm-oil afforded 95 feet. When oil-gas is subjected to a pressure of from twenty to thirty atmo- spheres, as in the process formerly conducted on an extensive scale for ren- dering gas portable, about one fifth of the bulk of the gas is condensed into an oily, volatile liquid, having a specific gravity of 821 ; when the pressure is removed, this liquid does not entirely reassume the vaporous state, and it may be preserved in ordinary well-stoppered bottles. Mr. Faraday ascertained the condensed liquid to be a mixture of several hydro-carbons differing considera- bly in their degrees of volatility. The boiling point of one is under the freez- ing point of. water, and is therefore gaseous at common temperatures. This body has the same composition as olefiant gas in 100 parts, but twice the den- sity. The principal constituent is a substance now known by the name of benzole, or benzin, which was found by Mr. Faraday to consist of carbon and hydrogen in the proportion of two equivalents of the former to one equivalent of the latter, and was hence called bicarburet of hydrogen. It was afterward observed by M. Mitscherlich to be the principal product of the decomposition of crystallized benzoic acid, when heated to redness in contact with lime. It is a limpid, colorless liquid, having the specific gravity 850. It freezes at 32° into a white crystalline mass, which melts again at 44° Fahr. Its boiling point is 186° ; and its specific gravity, in the form of vapor, at 60° is 2738. Its odor is peculiar, but not disagreeable. It is soluble in ether and alcohol, but insoluble in water. It burns with a bright flame and much smoke ; and, like most other of the denser hydrocarbons, when passed through a red-hot tube is resolved into carbon and light carburetted hydrogen. Its probable formula is Ci2 He. 42 GAS ILLUMINATION. Notwithstanding the great illuminating power of oil-gas, the abundance of the product, compared with that from coal, and the simplicity of the process, yet the commonest oil is far too expensive in this country to rival coal as a source of gas. Several extensive oil-gas establishments were erected at dif- ferent places in Great Britain, but aU these have gradually become converted into coal-gas manufactories. Not a slight objection to oil-gas is the gradual liquefaction which it§ most valuable constituents undergo on standing with exposure to moderate cold, to the great deterioration of the gas and the clog- ging of the pipes. § VII.— RESIN-GAS. Resin is another substance which may be advantageously substituted for coal in the manufacture of light-gas, where coal is not readily accessible. It affords an abundance of gas of excellent quality, nearly equal to oil-gas ; but the price of resin, compared with that of pit-coal, must ever prevent the for- mer from coming into successful competition with the latter in Great Britain. The attempt made, a few years ago, to introduce the manufacture on the large scale into this country proved a decided failure ; but in some parts of France resin-gas is, I believe, manufactured with success. The apparatus for making resin-gas is much the same as that for oil-gas. In the first attempts to obtain gas from resin, the oil-gas apparatus was used without any modification ; melted resin being caused to trickle as oil on the fragments of coke. But the exit-tube of the retort, which was carried to a considerable height to allow the return of some of the condensed volatile oil, became clogged by the bituminous matter which distilled from the resin. Pro- fessor Daniell overcame this difficulty, by conducting the exit-pipe from under the retort into a cistern, or hydraulic main, by which the return of the bitu- minous matter is effectually prevented. The construction of the apparatus. Fig. 13. as erected at Bow, near London, under the su- permtendence of Professor Daniell, for the late Resin Gas Company, will be understood with the assistance of the annexed figure. The re- tort a is charged with fragments of coke, and heated to bright redness by the furnace under- neath. The exit-tube b passes into an air-tight cistern, or hydraulic main c, wnich is kept cool by a refrigerator, and supplied with water from a cistern above. The volatile oil, which con- denses in c, is conducted into another cistern rf, by the discharge-pipe e. The uncondensed gas- es and vapors pass up the pipe /, and deposite more volatile oil in the cistern g, from which it is conducted into by a syphon-tube. From the cistern g the gas passes by the pipe h into the gasometer or other reservoir. The large quantity of volatile oil which is col- lected in this process is employed to dissolve the resin, instead of melting the latter alone. The commonest resin of commerce is put into the vessel i, and mixed with the oil in the proportion of about eight or ten pounds of resin to a gallon of oil ; the so- lution of the resin is assisted by the heat of the furnace below. The partition shown in the vessel i is a wire-gauze screen, to prevent any solid resin or im- purity from entering the retort. The dissolved resin passes through the stop- cock k, funnel, and syphon-tube, into the retort. The distilled oil contains a little acetic acid, formed during the process, which it is necessary to neutralize by the addition of lime before the oil is mixed with the resin. The quantity of oil produced is a little more than what is required for the solution of the resin. It is stated that a hundred weight of resin affords, in a properly-conducted MODE OF BURNING GAS. 43 operation, from one thousand to twelve hundred cubic feet of gas of the aver- age specific gravity 850. The illuminating power of resin-gas, compared with coal-gas, is as two to five : that is, two cubic feet of resin-gas afford as much light as five cubic feet of coal-gas. At an establishment in France, the illu- minating power of resin-:gas, compared with coal-gas, is estimated as five to nine ; one kilogramme of resin producing 497 litres of gas. The distilled oil is almost wholly transformed into gas, if quickly heated to redness. Turf-Gas. — A series of experiments was conducted at the gas-works at Newry (Ireland), by Mr. Peckston, in 1823, in order to ascertain whether gas could be obtained from turf ; from which he was led to conclude that, where that substance is abundant, it may be advantageously substituted for coals in the production of light-gas. According to M. Merle, the light of the gas ob- tained from turf is more brilliant tlian that of coal-gas (?). The gas is easily purified, and the charcoal which remains in the retorts answers perfectly for domestic purposes ; it gives considerable heat, and inflames readily. § VIII.— MODE OF BURiNING GAS. The quantity of light obtained by the combustion of gas is greatly influ- enced by the mode in which it is burned. The truth of this statement will appear from the consideration of the structure of an ordinary flame. A solid substance, which does not aff'ord a gas when heated strongly — a piece of iron or of charcoal, for instance — presents, at a red heat, the phe- nomenon of ignition, but it never produces flame. All combustible bodies, on the contrary, which are either gaseous themselves, or are convertible, partially or entirely, into a gas, as hydrogen, sulphur, and phosphorus, always burn with flame. Hence flame might at first be regarded as lurm?ious gaseous matter ; but we shall immediately see that such a definition can only be taken in a very limited sense. It is doubtful whether pure gaseous matter is, under any circumstances, ca- pable of becoming luminous. If a gas is capable of emittmg light when heated, it is certainly no more than a sensible glow, although the temperature may be sufficiently high to heat a metallic wire to whiteness. The air which rises from a gas-flame at an Argand jet is hot enough to heat a fine metallic wire to bright redness an inch or two above the highest part of the flame. The flame of pure hydrogen gas is so feebly luminous as to be scarcely visi- ble in broad daylight ; yet its temperature is sutficiently high to heat to white- ness a piece of thin platinum wire, or particles of lime thrown into the flame. The luminosity of flame, in fact, does not depend altogether on its temperature ; but on the presence of solid matter diff'used through the flame, and ignited by it, the solid particles acting as radiating points. Hence a luminous flame has been justly described by Davy as always containing solid matter heated to whiteness. No flame possesses less light than that of the oxhydrogen blow-pipe ; but, on introducing into it some solid infusible substance, the light that is emit- ted is too intense to be borne by the naked eye. The feeble luminosity of the flames of hydrogen, sulphur, and carbonic oxide is owing to the products of the combustion — namely, water, sulphurous acid, and carbonic acid — being gaseous at the temperature of the flame. On the other hand, the flames of phosphorus and of metallic zinc are very intense, because the products of the combustion — namely, phosphoric acid in the case of the former, and oxide of zinc in the case of the latter — are solid, and being diffused through the flame serve as radiating points for the light and heat. If the luminosity of flame depends on the presence of solid matter, where then is the source of the solid matter in the flame of gas or an ordinary combustible 1 The combustion of coal-gas — that is, the conversion of its hydrogen into water, and its carbon into carbonic acid, through the combination of these el- ments with the oxygen of the air — can of course only take place where the gas or vapor is in contact with the air. In an ordinary flame, such as that of a spirit-lamp, tallow-candle, or gas issuing from a' plain jet, the, gaseous matter is in free contact with the air only at the exterior of the flame, where 44 GAS ILLUMINATION. alone perfect combustion takes place. In the interior, combustible gases still tinburned exist. That such is the structure of the flame may be readily seen by depressing upon it a sheet of wire-gauze of small mesh (through which the flame is unable to pass), so as to view the flame in section. The i combustion is then seen to be limited to the margin of the flame. But if the structure of the flame is examined a' little more minutely, it is seen to consist of four parts, three of which are represented in the annexed "figure. 1°, The shaded interior represents the unburned combustible gas ; 2°, around this is the brilliant part of the flame, or the flame, strictly so called ; 3°, on the very exterior is another por- tion, hardly visible, but which may be perceived with attention in the flame of a tallow-candle ; and 4°, the blue flame at the bottom con- stitutes another distinct portion. In the blue part at the bottom, and on the very exterior of the flame, per- fect combustion of the gas takes place, the whole of the carbon and hydrogen uniting with the oxygen of the air to form water and carbonic acid, and with- out the production, therefore, of solid matter to aff'ord light. But in the lu- minous part of the flame, b, the supply of air is insufiicient for complete com- bustion. The carburetted hydrogen gas in this part is decomposed by the heat into free carbon and hydrogen, as when passed through a red-hot porce- lain tube ; the hydrogen alone, or principally, burns, while the carbon is de- posited in minute particles, which become heated to whiteness. The carbon does not burn entirely until it reaches the exterior of the flame. Thus the light of the flame of ordinary combustibles depends on the consecutive com- bustion of the hydrogen and carbon. The combustion of the hydrogen and some of the carbon serves to produce the requisite heat, and the particles of the remaining carbon radiate the light. The hottest part of the flame is just at the top of the luminous cone, where the combustion is perfect, but the air not in sufficient excess to carry away the heat quickly, as is the case in the exterior of the flame at the side and at the blue part at bottom. The heat in the centre of the flame is so low that gunpowder may be held there without being ignited ; even fulminating silver has been held for some seconds in the interior of a flame without explosion. The chemical effects produced on many substances by the exterior and interior parts of the flame are exactly op- posite. Just within the apex of the luminous cone certain metallic oxides are rapidly deprived of their oxygen and reduced to the metallic state ; but at the very summit of the flame, or a little beyond, the metals reduced from the same oxides re-absorb oxygen, reverting to the state of oxide. If a piece of clean copper wire is held at the very summit of the flame, it rapidly becomes covered with a coating of oxide ; but, on depressing the wire into the interior of the flame, the oxide is reduced, and the wire again becomes bright. That the luminosity of the flame of ordinary combustibles depends on the deposition of solid carbon, through the consecutive combustion of the carbon and hydrogen, may be proved by some interesting experiments with coal-gas. If that gas is mixed with an equal volume of air before being burned, it de- posites a smaller proportion of solid carbon, and loses half of its illu- minating power. On increasing the quantity of air the light is still fur- ther diminished. If a sheet of fine wire-gauze is held close to the orifice of a gas-burner, and the gas kindled above it, it will of course burn with its or- dinary brilliancy : but if the gauze is gradually elevated, so as to mix the gas with air in different proportions before it passes the gauze and burns, it will be found that the brilliancy of the flame diminishes with the height of the gauze ; that is, with the quantity of air mixed with the gas. At a particular elevation the gas burns with a faint blue flame, ' not more luminous than that of sulphur, and hardly visible in the direct rays of the sun. It is then mixed with the quantity of air necessary for the complete combustion both of the carbon and hydrogen simultaneously. The heat of such a flame is more intense than from the same quantity of gas burned in the ordinary man- ner, because the combustion takes place within a smaller compass in the for- mer than in the latter. The intensity of the heat is seen by projecting into it MODE OF BURNING GAS. 45 solid particles of some fixed matter, as oxide of zinc, which instantly become heated to whiteness. The conditions requisite to obtain the fiiil amount of light from a flame may be deduced from the consideration of the preceding facts. In the first place, the carbon and hydrogen must be burned completely, though not at the same place. When the combustion of the carbon is incomplete, the hame is smoky, and a large proportion of light is lost. As this arises from the gas being in too a large a proportion compared with the air, the remedy is obviously either the reduction of the amount of gas, or tlhe increase of that of the air. The great object of almost all improvements in the form of gas-burners and chimneys, is to aff'ord the means of increasing and regulating the amount of air brought into contact with the surface of the flame, so that the intensity of the combustion may be increased, witlhout any derangement of the order of the combustion. From a plain jet, the diameter of the orifice of which is a quarter of an inch, a flame higher thain two inches and a half can not be obtained without smoke : but the same amount of gas which would give a smoky flame from a plain jet may be made to burn with a clear and brilliant flame by extending or dividing the aperture of the jet, so as to give the flame a larger surface in contact with the air. The entire superficies Fig. 15. of the aperture need not be enlarged ; it may, on the contrary be diminished. In the place of a single aperture, the gas may issue, for example, from two holes drilled obliquely to make a cross flame, or from three holes, as fig. 15, which gives a I flame called the " cockspur." More light is obtained by such a jet than by the single aperture ; but the intermixture of air with the gas at the lateral jet prevents the deposition there of the proper proportion of carbon, so that tlhe full amount of light is not obtained. It is to be observed tha t the supply of air is required merely at the surface of the flame, and in no larger quantity there than is requisite to maintain a proper combustion. "When the same burner has several apertures, the light is improved by making them so near to each other that all the jets of gas shall unite laterally into one, as in fig. 16, which represents a semicircular jet of several holes, the flame from which is called the " union jet," or " fan ;" or as fig. 17, the aperture for which is a slit across the top of the beak ; the latter gives a sheet of flame called the " bat- wing." Of burners of this kind, that which seems to af- ford most light by the consumption of the same quantity of gas is the " fish- tail" or " swallow-tail" burner. In this the gas issues from a single small round bole in the centre of the top of the burner, but the single jet which is emitted is formed by the union of two oblique jets within the burner immediately before the gas is emit- ted. The result is a perpendicular sheet of flame, much the same in appearance as the " bat-wing" (fig. 37), but presenting somewhat more light at the bottom, on account of the smaller intermixture of common air with the gas at that part of the flame. The " fish- tail" burner and " bat- wing" are much more exten- sively used than the "fan," "cockspur," or any other of this description. Another method of increasing the proportion of air is by the burner known as the Argand, which allows the passage of a current of air through the cen- tre of the flame, as in the Argand oil-lamp. This burner pig. is. Fig. 19. consists of a circle of small holes of equal size, the cen- tre of the circle being open to admit an upward current of air. The view of this burner, from above, is shown in fig. 18, and in perpendicular section, in fig. 19. The ^iv internal current of air thus applied to the flame causes more combustion in the same time than with the plain Fig. 16. Fig. 17 46 GAS ILLUMINATION. jet, and therefore a higher temperature, but a sufficient quantity of solid car- bon is still deposited to radiate the light. The same amount of gas, which, proceeding from a plain jet, would give a very tall, smoky, and dull flame, would give a much shorter and more luminous flame from an Argand burner, without any production of smoke. The increase of light is far greater, if, in the place of air, pure oxygen gas is passed up the internal opening, as in the original* Bude light of JVlr. Goldsworthy Gurriey. The intensity of the com- bustion on the surface of the flame is greatly increased by the oxygen, but the consecutive order of the combustion is by no means disturbed. For the same consumption of gas, the flame from an Argand burner of or- dinary construction does not aff'ord so much light as the fiat flames from the " fish-tail" and " bat-wing" burners. The reason of this is obvious : as lumi- nous flame is opaque, each side of the interior surface of an Argand flame dif- fuses light into an apartment only above or below the flame on the opposite side. If the diameter of the circle of the burner does not exceed an inch (which may be taken as the average size), only a trifling amount of light is obtained from the interior surface of the flame. When a great deal of light is required, the most economical burner seems to be a large circle of " fish-tail" burners, with as little metal-work at bottom as possible, in order to allow the radiation of light from the interior surfaces underneath the opposite sides. The light from such a burner may be greatly increased by adjusting to the top of the flame a horizontal reflector formed of a circular piece of metal with a round opening in the centre, over which a short glass chimney should be placed. The lateral union of the " fish-tail" jets should be avoided, as smoke is thereby produced ; and if a profuse light is required, other jets may be placed behind the intervening spaces, so as to form a double circle. A burner of this construction was first introduced, I believe, by the Liverpool New Gas and Coke Companv, and named the " solar gas-lamp." When a considerable quantity of gas is burned together in one flame with- out smoke, the increase of light is much greater than the increase in the amount of gas consumed ; hence, when a great deal of light is required, there is always a saving in burning a considerable quantity of gas together! An Argand burner supplied with Cubic feet of gas per hour, H gave light equal to 1 candle, 2 " 4 candles, 3 « 10 candles. To obtain the full amount of light from any burner, the flame should al- ways be made as large as possible without smoking. The construction of the chimney may have a marked influence on the pro- portion of air brought into contact with the surface of the flame. A very wide, short, and cylindrical chimney, hardly increases or diminishes the pro- portion of air ; it is advantageous, however, in causing a more steady flame. But the draught of air is greatly increased if the chimney is tall and narrow, or Fig. 20 Fi. 21 F.. 22 coi^t'^acted toward the top, as figures 20, 21 ; or if it ^ ■ ^ ■ have a sudden contraction near the bottom, as in fig. 22. A short chimney with a slight contraction gives the flame a much better light than a wide chimney does, but the gas (or oil) is consumed faster in just the same proportion. Such a chimney is advantageous S S where a very strong light is required with a profusion J of gas, especially if the gas is unusually rich in car * r • • TT recently prepared oil-gas. A tangential cur rent ot air is produced by the contraction, which sweeps the outer surface oi thr J*"^ ^! the Bude light is nothing more than an ordinary gas-flame from two S^construcUon""^" concentric Argand burners, with chimneys and reflecting^fpLatus of part.^u MODE OF BURNING GAS. 47 the flame. The same effect is produced at the bottom of the flame by what is called the " double cone gas-burner," which is an Argand burner rising through a double brass cone terminating close to the top of the burner. The air rises between the two cones and impinges on the flame in a tangential current. . . Such are the means of increasing the proportion of air brought into contact with the surface of a flame, without diminishing the quantity of gas. But the inconveniejaces which arise from too much gas, or too little air, are not greater than those which proceed, on the other hand, from too great a supply of air. With a very great draught, two evils are likely to result : 1°, the in- termixture of air with the interior of the flame, which always happens in such a case to a greater or less extent, produces a more complete combustion of the carbon than is proper ; aad 2o, a rapid current of air in larger quantity than is necessary for the combustion of the gas, carries away the heat, and thus pre- vents the flame from attaining its maximum temperature. If a gas-flame from a large Argand burner of several holes be depressed (bv turning the stop-cock, of the jet) until the yellow -flame disappears, the flame which remains is blue, and so feebly luminous as to be hardly visible in broad daylight. But the same or a smaller quantity of gas when made to pass through three or four holes, as by shutting off" the remainder of the holes with a flat glass plate, will give a far more luminous flame. In the first case, the proportion of air is so large as to cause complete combustion of the carbon and hydrogen at the same time, but not so in the latter case. When a jet of gas issues froin a small orifice with great velocity, it becomes mixed by expansion with atmo- spheric air, and the deposite of carbon is consequently deficient. A great loss of light is' also experienced with a very tall chimney, on account of the ra- pidity and completeness of the combustion through the unnecessary draught. Of late years gas has come into very general use in the chemical laboratory as a source of heat. The most convenient mode of applying it for this pur- pose is in the form of the inflammable mixture with air. The mixture affords a very intense heat, because a considerable quantity of gas is consumed within a small compass, and it has the advantage of giving a flame without smoke. The apparatus represented in figure 23 is lound advantageous for this purpose- The mixture of gas and air is made in the chimney ; a piece of wire-gauze is fastened over the top, above which the in- flammable mixture is igni- ted : a is a copper chimney, supported by the ring of a retort-stand having a ridge or pegs for that purpose on the outside ; the bottom is open to admit air : 5 is a plain gas jet, the extremity of which is near the bottom of the chimney ; the crucible or capsule to be ignited is supported over the flame on a triangular piece of iron wire, placed on another ring of the retort-stand : c is a sec- ond chimney or jacket to be placed over the crucible, to cre' ^e a constant and equal dri ; fht. The proportion of ga. ! md air is regulated by thej 5top-cock d, and by rais- ing or depressing the chim Fig. 21 ney over the extremity of the gas jet. The flame should not bum yellow, but 48 GAS ILLUMINATION. u ^^"^ ^° produce any deposite of carbon on a body held in it. A little experience will show what kind of flame produces the most intense heat. Ariother excellent mode of obtaining heat through the combustion of gas is by adapting to an ordinary Argand burner a chimney with a contraction, sim- ilar to hg. 22, made by simply fastening a circular disc of copper with a round hole m the centre into a common cylindrical copper chimney. It is said that the temperature is further increased by punching out a circle of small holes m the disc, as in the top of an Argand burner. The attention of the pubhc has been lately drawn, by Mr. Faraday, to the necessity of paying more than ordinary attention to the proper ventilation of gas-lights. The importance of this subject will be readily admitted when it is considered that one part by weight of well-made coal-gas produces in com- bustion nearly two and a half parts by weight of carbonic acid ^as. If at- tempted to be breathed in a state of moderate dilution with air,* that o-as soon proves fatal ; and causes asphyxia, even if largely diluted. Thou^rh the atmosphere of a chamber would hardlv acquire from gas-lights the quantity necessary to produce such effects, yet the continued respiration, for several hours, of air contammg not more than one or two per cent, of carbonic acid IS known to have produced alarming effects. But carbonic acid gas is not the only deleterious product of the combustion of coal-gas. Unfortunately, none ol the ordinary operations of purification will withdraw the whole of the bi- sulphuret of carbon which is contained in coal-gas, from whatever kind of coal the gas may be made. Bisulphuret of carbon, composed, as its name implies ot carbon and sulphur, is a liquid at common temperatures, but so very vola- tile that It IS retained in the state of vapor bv" the gas, though exposed to a very low temperature. In the combustion of gas containing this vapor the sulphur becomes sulphurous acid, which, bv the action of moisture and the oxygen m the air, passes into the slate of sulphuric acid, or oil of vitriol Ihis corrosive liquid attaches itself to the walls and furniture of the apart- ment and, bemg very fixed, does not dissipate by evaporation and ventilation. 1 he destruction of the bindings of the books in the library of the Athenaeum Club was partly attributed by Mr. Faraday to the action of sulphuric acid thus formed and condensed on the backs of the books. The water collected in a receiver from the combustion of gas at the Athenaeum gave abundant evidence of tiie presence of sulphuric acid when tested by chloride of barium t ine common mode of carrying away these deleterious vapors, where any means at all are had recourse to, is suspending at a little height above the chimney of the lanip a bell-shaped vessel, connected at its top with a narrow tube, leading out of the apartment. The diameter of the bottom of the bell- vessel IS usually much greater than the diameter of the chimney of the lamp. 1 he ventilation, or the ascent of the hot air from the lamp through the bell- Shaped vessel and tube, takes place with a rapidity corresponding to the dif- ference between the density of the hot air Avithin and the external cold air. As the difference in density depends on the difference in temperature, to have a vigorous draught m the tube it is necessary to keep up the temperature of the latter as high as possible. But the extent of surface presented by the bell-vessel a lows so much of the heat to escape by radiation; that sometimes the temperature of the tube is scarcely raised above that of the surrounding atmosphere, in which case ventilation hardly takes place at all. This incon- venience may be surmounted (as shown by Mr. Faraday) by dispensing with lmPtp7nf tl ^^''^''^f^ and conducting a copper tube of about the'same «ntwS f "I""' 5°"? the flame to the exterior of tne hS^i^^u i u P/^^ed, the copper tube necessarily becomes more strondy heated than the bell-vessel in the common mode of ventilation : a rapid ml lf«Vr *^?tf ^^'hed : not only are all the products of the combustion of the gas carried away, but even the external air itself may be sucked in at the top 4lEfS^r^?-r"-^^^ T iiecture at the Royal Institution, April 7, 1843. ECONOMY OF GAS ILLUMINATION. 49 of the chimney. If any objection can be raised to this mode of ventilation, it consists in the rather unsightly appearance of the tube so near the flame. A very elegant lamp was devised by Mr. Faraday (and patented by his brother), in which the ventilating current is made to descend between two concentric glass chimneys of unequal height, the interior being the lowest, and to pass from the bottom through a tube, which is afterward bent up- ward. The burner is an Argand, supplied with air in the ordinary manner ; the tube to conduct away the gases, or ventilating pipe, terminates in a box at the bottom of the lamp, formed of two concentric cylinders, the space be- tween which is closed at bottom, but open at top, in order to communicate with the space between the two chimneys ; the Argand burner, with the air necessary to feed it, rises through the interior cylinder of the box at the bot- tom of the lamp. The exterior chimney, which is the highest, is covered with a plate of mica. The descending current is determined, in the first place, by applying heat for some time to the bend of the ventilating tube where it begins to ascend ; when fully established, the gas is lighted, and the exterior chimney covered with a plate of mica. The gases from the flame then pass from the top of the interior chimney, downward through the space between that .and the ex- terior chimney, into the box in which terminates the ventilating pipe to con- vey the gases without the apartment. A globe of ground glass now placed over the lamp gives it a very elegant appearance. It is said that a greater amount of light is obtained with such a lamp from the same quantity of gas, and certainly a larger flame is afforded without opening the stop-cock further ; but it seems probable that the force of the draught sucks up a little more gas than would otherwise be emitted. Particular attention must always be paid in this lamp to determine the downward current fairly, by applying heat to the bend of the ventilating tube before the gas is lighted. The neg- lect of this is sure to be attended with the destruction of some of the glass paints of the apparatus. § IX.— ECONOMY OF GAS ILLUMINATION. • From the statements contained in the preceding section, it is evident that the amount of light obtained from the combustion of gas, and hence the rel- ative economy of gas-light, depends in no inconsiderable degree on the man- ner in which the combustion is eflfected : and, as the cost df the production of gas entirely depends on the facility of procuring coal, and of disposing of the by-products of the manufacture, which must vary more or less in every locality, it is impossible to make an estimate of the advantage of gas illu- mination in an economical point of view of general application. The follow- ing considerations on this subject have especial reference to the London gas- works. The average cost of a ton of Newcastle coal, delivered at the work? in London, may be takea at seventeen shillings, and the value of the products from the same quality of coals as follows : — £. s. d. 8,500 cubic, feet of gas at 9«. per 1,000 cubic feet 3 16 6 36 bushels of coke 0 12 0 12 imperial s;allons of ammoniacal liquor 0 0 3j 190 pounds of tar 0 4 0 4 12 9i According to this estimate there is yielded for every ton of coals about 3/. 15s. 9d., to be placed against the current expenses of the manufacture and the capital. The fuel employed to heat the retorts in London is coke, of which there is required a little more than one third of the amount produced ;* there- fore four shillings and threepence may be deducted from the above estimate for fuel. About two thirds of a bushel of lime, which costs, say ninepence, *A ton of coals requires about thirteen bushels of coke (heap measure) 4 50 GAS ILLUMINATION. is required to purify the gas from a ton of coals. Where alum, green vitriol, sulphate of manganese, or sulphuric acid, is employed to separate ammonia, the value of the ammoniacal salt formed is a little more than the original cost of the material. After making the above deductions, there remains 31. 10s. 9d. per ton to be placed against the wages of workmen, salaries of man- agers, clerks, and collectors, repairs, and interest of capital. Such is an outline of the advantages of this manufacture to the producers, where the annual consumption of gas amounts to three thousand millions of cubic feet, and where more thaa thirty thousand street lamps are supplied at an average price of four pounds per lamp per annum. In small establish- ments the profits are considerably less. It appears that, in most localities in the south of England, where about one hundred lights are required, a coal- gas apparatus may be found profitable ; but the recent improvements in the construction of oil-lamps render it doubtful whether a gas apparatus would be advantageous for less than a hundred lights. With reference to the economy of gas illumination to the consumer, Mr. Peckston offers the following considerations (Practical Treatise on Gas-light- ing, 3d edit., p. 27). An imperial gallon of sperm-oil burned in an Argand la.mp, which yields light equal to five candles, will burn about 100 hours, or give an amount of light equal to 500 candles burning one hour each ; the ex- pense per hour, when sperm-oil is nine shillings per gallon, will be a little more than a penny for such a lamp ; but when whale or seed oil, at three shillings, or three shillings and sixpence per gallon, is substituted for sperm- oil, and the solar lamp used, which furnishes light equal to 4| mould candles of six to the pound, an imperial gallon will burn about 90 hours, and give a total amount of light equal to 4275 candles, each burning one hour. The solar lamp with whale or seed oil costs something less than a halfpenny per hour. It is generally admitted that an Argand burner of fifteen holes, con- sumes about five cubic feet of gas per hour, and yields light equal to twelve mould candles of six to the pound. Takins: as a standard the amount of light which would be produced by a certain number of^wax candles of six to the pound, the relative cost of that amount of light from other sources is the following : — Wax candles lOO-O Sperm oil burned in Argand lamps 49-6 Ill-snufTed tallow candles 49-6 Tallow candles (mould) six to the pound .... 36-8 Whale or seed oil burned in the " overflowing shadowless lamp," or the " solar lamp". . . 23-4 Coal gas 10-0 Or, if the cost of wax candles is estimated at one shilling, the cost of the other sources of equal light, will be as follows :— £. s. d. Wax 0 10 Sperm oil 0 0 6 Ill-snufTed tallow candles ... 0 0 6 Tallow candles 0 0 41 Whale or seed oil 0 0 2f Coal-gas nearly 0 0 1| • The following table, showing the relative intensity and cost of light ob- tained from diflerent sources, was constructed by Mr. Rutter, engineer to the Old Brighton Gas Company. The cost of gas is estimated at ten shillings per 1000 cubic feet, and the numbers in the third column represent the number of cubic feet of gas which afford as much light as the quantities of the materi- als mentioned in the first column. ECONOMY OF GAS ILLUMINATION. 53 1. 2. 3. Cubic feet of gas. 4. Cost of gas. Source of light. Cost. 1 gal. whale (solar) oil 1 gal. sperm oil 1 lb. wax candles 1 lb. fallow candles (moulds) *. d. 0 8 1 0 2 6 3 6 9 0 21 25 25 175 217 s. d. 0 2i 0 3 0 3 1 9 2 2 Ihe table m the following page is a copy of a paper laid before a Commit- tee 0/ the House of Commons, by Mr. Hedley, of the Alliance Gas Works, Dublin, showing the relative economy of the gas manufactured at different places m this kingdom, compared with candles. The price of one hundred pounds of the candles referred to is 3/. 25. 6c/., and that quantity is estimated to bum, one at a time, for five thousand seven hundred hours. 52 GAS ILLUMINATION. Specific gravity of tlie gas. Net cost of gas equal to 100 pounds of candles. I- O O O CO CO lO O r TH n (H -rf ci ooo- ■ffOOOOO-^iOlOJ— CO CO S mcoOCTih-coco'*coco oo o >p 0 .5 a! i -S o 2 § a V a ESTIMATION OF THE VALUE OF LIGHT-GAS. 53 Concerning the relative economy of coal-gas and oil-gas as sources of light, no estimate can be offered of constant application, as the price of oils, from the precarious nature of the sources from which they are obtained, is subject to considerable fluctuation. If the relative cost of light from coal-gas and oU- gas is estimated as one for the former to five or six for the latter, the cost for oil-gas is probably under the truth. But the illuminating power of oil-gas is far greater than that of coal-gas, taking bulk for bulk. Recently prepared oil-gas has occasionally more than three times as much illuminating power as coal-gas ; the average is about the proportion of 1 of coal-gas to 2.6 or 2.7 of oil-gas. The following table, by Drs. Christison and Turner, shows the rel- ative illuminating powers of these gases at different densities :— Density. , ' Proportion of light. A r Coal-gas. Oil-gas. Coal-gas. Oil-gas. 659 818 100 140 578 910 100 225 605 1110 100 250 407 940 100 354 429 965 100 356 Mean 535 948 100 265 Of oil-gas of the specific gravity of 900, an Argand burner, giving a light equal to seven mould-candles, consumes a cubic foot and a half per hour. § X.— MODES OF ESTIMATING THE ILLUMINATING POWER AND PU- RITY OF LIGHT-GAS. The only method of strict accuracy by which the value of an illuminating gas may be determined, is by a complete chemical analysis; but this is an operation of extreme delicacy, requiring far more adroitness in minute manip- ulation than IS possessed by the generality of gas engineers. Results, how- ever, of sufficient accuracy for all ordinary purposes, mav be readily obtained by methods much more easily executed ; namely, 1°, by a photometrical ex- periment ; 2°, by determining the specific gravity of the gas ; and 3°, by de- termming the quantity of oxygen required for the complete combustion of the gas, with the amount of carbonic acid produced. The first of these methods IS the simplest; and the results it affords, when performed with care, are equal in value to those got by the two other methods. The photometrical processes which I shall briefly describe are founded up- on principles of extreme simplicity. Though the eye is unable to judge with precision of the relative intensity of two lights, yet it can determine with con- siderable accuracy when contiguous shadows of an opaque object thrown upon a screen by different lights are equally dark-, or when two similar adjoining surfaces are equally illumined, provided the lights are of the same teint. If the two lights which produce these effects are equal in intensity, obviously their distance from the screen must also be equal ; but if unequal, the most intense light is placed farthest from the screen. Now, as the rays of light are propagated continually in straight divergent lines, their intensity dimin- ishes in the direct proportion of the square of their distance from their source, iakmg, as a standard, the amount of light on a screen derived from a flame at the distance of one foot, then at two feet the light on the screen from the same source would be one fourth, at three feet one ninth, and at four feet one sixteenth of the standard. Therefore, if two or more sources of light are so placed as to cast an equal light on the screen, their relative intensities are di- rectly as the square of their distances from the screen. The objection to this mode IS, that it does not readily admit of a fixed standard of comparison. i he method of contrasting the shadow of an opaque object formed by dif- ferent lights was first employed by Lambert {Photo?netria, 1760), but is com- 54 GAS ILLUMINATION. monly attributed to Count Rumford, by whom it was proposed in the PhiL Trans., vol. Ixxxiv. The apparatus required is extremely simple, consisting merely of a smooth perpendicular surface of uniform color, and a rod for throwing the shadow. The two lights which are to be compared are so placed that, when the rod is interposed between them and the screen, the two shadows may be contiguous ; and, so long as the shadows are of unequal depth, one of the lights must be advanced toward, or retired from, the screen, until an -equality in depth is procured. Suppose a wax candle at the distance of two feet, and a gas jet, at the distance of two feet six inches, to produce equal shadows, then, according to the above rule, the relative intensity of the lights is as 4 to 6.25, or as 1 to 1.5625. Similar in principle is the elegant little instrument constructed for the same purpose by the late Dr. Ritchie, by which a very correct estimate may be made of the relative brightness of two lights, provided they are of the same teint. The apparatus, which is shown in section lengthwise in figure 24, consists of a rec- F'S- 24. tangular box about two inches square, open at both ends, and blackened upon its inner surface to absorb extraneous light. •> On the top of the box is a narrow slit about one inch long and one eighth of an inch broad, covered with tissue or oiled paper. Within are placed two rectangular plates, a, i, of plane looking-glass, cut from the same piece to ensure uniformity in reflecting power. Their width is the same as that of the box, and their length may be equal to the hypoth- enuse of a right-angled isosceles triangle, whose side is the height of the box, or a little less, as in the above figure. The plates are fastened together so as to meet at the top, in the middle of the slit (or in the line of that perpendicu- lar), their reflecting surfaces being toward the open ends of the box. In using this instrument, it is placed in a straight line between the two lights whose intensities are to be compared, so that the light from each source is reflected from the respective mirrors to the tissue. The instrument is then moved nearer one or the other light, until, to an eye situated above the box, the two portions of the slit which correspond to the respective mirrors appear equally illuminated. The squares of the distances of the lights from the vertical c, give the proportion of the intensities required. A very ingenious and accurate mode of determining when two rays of light from diflferent sources have the same intensity, has been proposed by M. Arago ; but this method will hardly supersede those just described, at least for the use of gas engineers, until a more simple apparatus is devised for its application. The method of M. Arago is founded on the property possessed by a ray of light of dividing itself, when polarized and passed through a doubly refracting prism into two rays of the complementary colors, red and green. Rays from the two lights which are to be compared are polarized by the ordinary means, as transmission through a plate of tourmaline, or reflec- tion from glass at the polarizing angle, then received on a plate of rock crys- tal, and observed through a doubly-refracting prism. Each light will then give two images tinged with red and green. On bringing the images into such a position that the red of one light falls over the green of the other, if the intensities of the two lights are equal, the superposition completely neutrali- zes the color, and a white or colorless image is the result ; but if the intensi- ties are unequal, the image is slightly colored with red or green, according as the one or the other predominates. Another mode of estimating the illuminating power of coal-gas is by deter- mining its density ; the light aff'orded by illuminating gases being in general proportioned to their density. The most valuable constituent of coal-gas, namely, olefiant gas, has the density 997 (air as 1000) ; the next in value, light carbur'etted hydrogen, has the density 560 ; and the density of hydrogen, which is the principal deteriorating constituent, is 69. Thus far it would seem that the illuminating power of coal-gas might be estimated with accuracy by ta- ESTIMATION OF THE VALUE OF LIGHT-GAS. 55 king its density ; but, unfortunately, carbonic oxide and nitrogen, which are of no value as sources of light, are heavy gases compared with light carbu- retted hydrogen and hydrogen. The density of carbonic oxide is 967, and that of nitrogen 970. Hence the estimate thus obtained can not be relied on in all cases. The density of the gas may form, nevertheless, a valuable datum in the estimate, as appears from the following results of some experiments by Mr.Hedley*:— . . ^ Number of candles equal to gas when mrnea Density of gas. in a single jet four inches high. 412 ) • S 1'562 412 5 specimens J j.^gg 420 1-645 424 448 453 455 462 466 528 530 534 539 580 1-234 1-453 1-929 1-929 1-777 1-826 1- 826 2- 228 2-295 2- 441 3- 306 Fig. 25. The late Dr. Henry, whose researches on coal-gas form the subject of me- moirs of great interest, considered that the comparative value of the different light-gases may be accurately determined by the quantity of oxygen required for the perfect combustion of equal volumes, and the quantity of carbonic acid produced thereby. The larger the proportion of hydrocarbons present, the great- er amount of oxygen will be required ; light carburetted hydrogen requires more oxygen for combustion than carbonic oxide or hydrogen, and oleflant gas more than light carburetted hydrogen. In fact, both the illuminating powers of the different gases, and the amount of oxygen required for their combustion, de- pend in a great measure on the proportion of gaseous carbon contained m one volume of the gas. If one hundred volumes of one gas require for perfect combustion one hundred volumes of oxygen, and one hundred volumes of another gas require two hundred volumes of oxygen, the value of the second will be double, or a little more than double that of the first. A convenient instrument in which to cause the combination of the gas with oxygen is Dr. Ure's Eudiometer, represented in figure 25. It is formed ol a stout glass tube about twenty inches in length, and a quarter of an inch internal diameter, sealed at one end,' and doubly bent at the middle. Th^; limb with the sealed end is graduated into equal parts according to an arbitrary scale. Two pla- tinum wires are sealed into the glass near the closed end, with their extremities within the tube about one tenth of an inch apart. On placing one of these wires in communication with the knob of a charged Leyden jar, and the other with the outside of the jar or the ground by a f ' metallic chain, the electric spark passes within the tube. In the first place, a mixture of the gas to be tested, and pure oxygen, in known propor- tions, the oxygen being in excess (say, three vol- umes of oxygen to one volume of the gas), is made in a graduated jar at the water-trough. Enough of this mixture is transferred to the eu- diometer, previously filled with water or mercury, to occupy about two inches * For a short account of the method of obtaining the density of gases, see "Elements of Chem ical Analysis," p. 274 ; and, for more minute details, consult Faraday's " Chemical Manipulation. 56 GAS ILLUMINATION. of the sealed end ; and the amount of the mixture introduced is carefully ob- served, the liquid standing at the same level in both limbs. The mouth of the open limb is now closed with a cork, which is secured by a wire and the electric spark taken through the wires. The gaseous mixture explodes and immediately afterward a contraction is perceived from the condensltion of the steam formed by the combustion. The gas which remain?, supposTng the combustion to be complete, consists of the excess of oxygen, carbonic acid formed by the combustion and the nitrogen in the coalias. l?e Cuid is agam brought to the same level in both limbs, and the measure of the^as s accurately noted : the carbonic acid gas is next absorbed by agitating the gas with a little solution of caustic potash ; for which purpose it is conven ent ?c mtroduce a few fragments of iused potash through the open end of the Tube and shake them mto the sealed limb. With a slight agitation the who e of the carbonic acid is immediately absorbed. The measure of the rema^nin^ gas being noted, and the closed end of the instrument completely filled wTth water, by a litt e dexterity the gas is brought into the limb with the opened The ms rument being mverted (the bend upward), and the open end under water at the pneumatic trough, a stick of phosphorus attached to a piece of copper wire is introduced mto the open limb and brought into contact with the gas. The phosphorus soon absorbs the excess of oxygen in the mixture an ^ what remams IS the nitrogen of the coal-gas, to determine the amounfof which t must be returned to the sealed limb. The excess of oxygen, and theTefore the quantity required for the combustion, is also then ascertained. The resSts obtained should always be tested by a second similar experiment; and by a third, if any discrepancy is observed in the first tw6 results ^ From the data obtamed by such an experiment, tlTat is, the volume of oxv- gen emp oyed m the combustion, and the volume of carbonic acid produced a tolerably accurate estimate of the value of illuminating gases may be formed! The reason of this will appear on examining the result of the combustion wfth pure oxygen of each of the combustible gases contained in coal-gas ^"'^ Name of gas. 100 vols, gas require Contraction of the mix- Vols of carbonic Olefiant^as °'^Qnf''*i t^re after explosion. acid produced. Uleftant gas. . . . . 300 vols. one half 2OO Light carburetted hydrogen... 200 " two thirds 100 Hydrogen... 50 « complete Carbonic oxyde 50 " one third lOO That a relation generally subsists between the amount of oxygen required and the value of the coal-gas, may be perceived by the table atplge 34, show: ing the composi ion of coal-gas evolved at different periods of the disti lation See also the table of the composition of oiJ-gas, pao-e 41 buiiduon. For the complete analysis of coal-gas, the process given in the following table seems to be the best we are. possessed of, but it is not altogether fref from objections. The chief source of error lies in the determination of the carbomc oxide and hydrogen, for potassium, at a particular temperature ah- sorbs some hydrogen as w;ell as carbonic oxide, but this circumstance does not mterfere with the estimation of the important constituents of coal-gas ESTIMATION OF THE VALUE OF LIGHT-GAS. 57 p o f P g-o S P » s- " 52. £L » c =^ — o 3f? t? M o , g E' S a> s • g t3 aq & a: P c-5 § ^ tn _^ ft ^ fD ^ f B ITS D" _ M 3 3 o 2. P p o S 7 ^ p- O M n ^ » o a o i cr' — . 2 a ^ p P vP* Oq ^ p s 2, — P Oq c c 2' <^ S! g o s c ™ • ^ * g ^ S B S " P e - ►J p (t a> i-i "-^ =2 2 fo 2 _ 5^ 2. ^ hH fa '* < 3 sr Co p p a 0 a- CL o ,^ g 3 — 5 p O m p fD ^. o- S- & O P rt- ft f=»- cr P t^Tp (ti to . 5 i-( P- P" o CD § o w. 2. rt- 5 ~ el si P" (B 'S, ^ p» S g-g. p CO S » cr. o o" p O "5 P 3 ■ o S S S. 3 P Sg-^ CD fB « a p CO SI- p.. (Ti p ^ p &». CD p o B < (t (jq 3 ^ B ^ *5 p p tr-aq P oq oq P 3- o p p p p a. s g ^- pp ^ p- p- P 3>g CO Cfq ^ I ? O o n P I P o P p* C. CM 58 GAS ILLUMINATION. In the preceding method of analyzing coal-gas, the defiant gas and vapors ot hydrocarbon are estimated together as the contraction by chlorine. The determination of the hydro-carburetted vapors may be accurately effected as shown by Mr. Faraday, by means of oil of vitriol. That liquid absorbs both the vapors and olefiant gas, but the latter not so rapidly as the former • and il the coal-gas is diluted with three or four times its volume of atmospheric air or hydrogen, and the mixture kept in the shade, the absorption of olefiant gas is prevented. Another portion of the gas under examination may be taken lor the remaining operations. As the principal luminiferous constituents of light-gas are olefiant gas and the vapors of hydrocarbons, a good approximation to its true value may be obtained by determining merely the contraction which the gas experiences when mixed with chlorine, neglecting the other operations in the preceding method ol analysis ; and instead of removing the excess of chlorine by caustic potash at the close of the experiment, the amount of chlorine absorbed by water m similar circumstances may be noted and deducted from the entire condensa- tion. The necessity of carefully excluding the mixture from solar light, arises froni the property which chlorine possesses of condensing carbonic oxide under the influence of solar light and moisture ; but no condensation from the pres- ence of carbonic oxide takes place in the dark, or in candle-light. The purity of the chlorine employed in this process should be previously ensured by as- certaining whether it is absorbed by water, or by a dilute alkaline solution without leaving a residue. The chlorine should be added to the gas so Ions as the volume of the latter diminishes. § XL REGULATORS AND METERS. The flow of gas from the gasometer for distribution along the pipes is not commonly regulated by a stop-cock, but by a water or mercurial valve, which IS, m fact, merely a small and very delicate gasometer. The water-valve has precisely the construction of the ordinary gasometer, excepting being square and the upper part having a vertical partition descending about half way from the covered top to the bottom ; not so far as the surface of water in the cistern except when it is required to cut off the supply of gas entirely. This parti- tion is placed between the entrance and exit pipes, so that, in proportion as the weight of the counterpoise is diminished or increased, the partition approaches or recedes from the surface of water in the cistern, and of course retards or permits the flow of gas from the entrance to the exit pipe. The flow of gas is, theretore, regulated by the weight of the counterpoise. With this small gasometer is sometimes connected a vertical rod, which carries a black-lead pencil made to bear upon a paper cylinder; the latter rotates on its axis by communication with a time-piece. By this contrivance every change of pres- sure which may take place during the absence of the observer is shown by the aberration of the line ; it is, therefore, a pressure register. A sufliciently precise idea of the construction of the mercurial valve may be formed by the consideration of fig. 26. In this apparatus the cistern is the moveable part to regulate the flow, the upper part be- ing fixed ; a and b represent the tAvo gas-pipes termi- . nating in a rectangular iron vessel c, open at bottom, which dips into the cistern d, containing mercury up to the level e. By means of a screw working against the bottom of the cistern, the latter is raised or lowered so as to bring the surface of mercury nearer to, or to draw it further from, the vertical partition/, by which the flow of gas is impeded or retarded at pleasure. The screw may be turned by an index working over a graduated circle, by which the- exact size of the open- ing between the bottom of the partition and the sur- _ - face of mercury may be indicated. Bi large gas-works a regulator of a more complicated construction is made Fig. 26. REGULATORS AND METERS. 59 Fig. 27. use of, so contrived as to preserve at all times a given rapidity in the passage of gas, however fluctuating the pressure of the gasometer. The principle of the action of this instrument, different modifications of which are made use of, may be understood by reference to figure 27. It consists of a rectangular cistern con- taining water up to the level a a ; b is. the part which answers to the gas-holder of the ordinary gasometer, sustained at any re- quired height by chains working over the pulleys c c, and bearing the counterpoise d. The gas enters by the pipe e, and passes out by /. Within the entrance-pipe, which is contracted at top, is suspended by the chain g, a cone h, the base of which is a little wider than the aperture at the top of the pipe. Whenever the pressure on the gas- ometer is increased, the weight of the coun- terpoise d remaining the same, the vessel b rises, lifts the cone, and contracts the aper- ture through which the gas enters. By properly adjusting the length of the chain the flow may be at all times equally maintained, having been first adjusted by the counterpoises. The pressure in the gas- ometer may be ascertained and registered as in the common water-valves. Platow's " gas moderator" is an ingenious instrument for preserving a uniform flow of gas on the small scale. The extremity of the tube which supplies the gas is immedi- ately opposed by a disc, which is connected with a spring and crank in such a manner that when the former would be driven from the extremity of the gas-pipe by an increased flow of gas, if not subject to the action of the spring, the latter causes the disc to approach the tube, and therefore offer an impediment to the flow of the gas. These parts of the moderator are enclosed in an air-tight cylinder hardly exceeding two or three inches in length, from the top of which issues the gas delivery-tube. The consumers of light-gas in London, and many other places, are now generally required by the respective gas companies to burn the gas by meas- ure. The principle of the action of the ordinary gas meter, or apparatus for measuring the quantity of gas which passes through a pipe, may be understood with the assistance of figure 28, which represents a section of the working part of the apparatus perpendicular to its axis. This part consists of a cylindrical case a, within wllich revolves a shorter cylinder b, shut at both ends, and divided into four compartments by the partitions c, c/, e, /. Each compartmeni commu- nicates with the exterior vessel by slits on the periphery of the cyhnder. The size of the diam- eter of the cylinder of a meter to supply five.' lights is about thirteen inches. About two thirds of the cylinder revolve in water, and the gas en- ters the space above by the elbow tube g, which enters at the axis, and terminates imrnediately above the surface of the water. As the gas en- ters, and exerts a pressure against the partition c, it causes the cylinder to revolve on its axis from left to jight ; and, when the slit h gets above the surface of the water, the gas in that compartment escapes into the exterior cylinder, whence it is con- ducted a way by a tube not shown in the figure. Connected with the oppo Fig. 28. 60 GAS ILLUMINATION. site end of the axis of the cylinder is an endless screw, which moves a toothed wheel attached to an upright shaft, and the latter communicates with the dial-work of the registers, by which the number of cubic feet of gas which pass through the apparatus in a given time can be read olF.* Clegg's patent dry gas meter" is an ingenious apparatus, intended to show the quantity of gas which passes through it, by measuring the temperature of a little brass cylinder heated by an inflamed jet of the gas. Tlae jet pro- ceeds from the side of a small brass knob about an inch and a half long ; the upper part of which is without the meter. The bottom of this knob, within the meter, is connected at right angles with a hollow brass case, called the heater, about two inches long, and half an inch broad. The gas enters the meter at a prolongation of one extremity of the heater; a minute quantity passes up the knob, and out at the jet, but the bulk of the gas escapes froin the heater downward into the body of the meter by three descending tubes, each about three quarters of an inch in length. By its passage through the heater and the three descending tubes, the gas becomes heated ; a measure of its temperature would, therefore, other circumstances being equal, be a measure of the intensity of the combustion in the small flame issuing from the knob at top. The manner in which the temperature is measured and the registration ef- fected, may be understood by reference to fig. 29 ; a is the cone, the dot in which represents the aperture through which the jet of gas issues ; b is the heater in cross-section ; c one of the tubes descending from the heater, by Fig. 29. which the gas enters the body of the meter; d is a glass instrument similarly constructed to the differential thermometer of Leslie; but e and/, instead of being two round bulbs, are two cyl- inders of three inches in length. This ther- mometer, the cylinders of which are half-filled with alcohol and exhausted of air, is made to vibrate by the rod o- on the centre h, and is bal- anced by the weight i. Supposing the appara- tus in action, and the thermometer placed as in the figure, the heated gas descends through the three tubes, of which c is one, and impinges on the top surface of the cylinder/. The vapor of alcohol in this cylinder is immediately expand- ed, and drives the liquid into the cylinder e ; the . . latter soon becomes the heavier, and descends until it lies immediately under the tube c, when it becomes heated in its turn and again rises. A pendulous motion is thus kept up so long as the gas flows, and the jet in the knob continues burning; and each vibration, being communicated to a train of wheel-work, is registered in the ordinary manner. The number of vibrations in a given time corresponds with the intensity of combustion in the small jet of flame from the knob, which is nearly, though not exactly, proportional to the quantity of gas which passes through the meter. Cast-iron hoods, not represented in the figure, project over the upper glass cylinder on each side, which serve to carry off" any superfluous caloric, so that the temperature of the heater and that of the hood which surmounts the top glass cylinder may bear the same relative proportion to each other, whatever the temperature of the external atmosphere. A meter of this construction, * Considerable sensation has been lately excited among the gas consumers of the metropolis in consequence of the allegations contained in a pamphlet on gas meters, by Mr II. Flower in which the author proves that the registry of the ordinary gas meter is subject to an excess over the ac- tual amount of gas transmitted amounting to from eight to thirty per cent. The chief source of error seems to consist m the want of a proper adjustment of the surface of the water. An undue quantity of water in a meter, according to Mr. Flower, will make an excess of about twenty per cent, in the amount registered over the quantity actually consumed. In Edge's " improved gas meter, an excess of water is prevented by having an open tube or waste-pipe leading from the proper surface of the water downward into a close cistern, or waste-water box, from which it is withdrawn when requisite, by an opening at bottom. NAPHTHALIZED GAS. of about five inches in diameter and four inches deep, is said to be sufficiently- large to measure gas for six burners, and is called " a six-light meter." Nei- ther the temperature nor pressure of gas from the main affects the indications of this meter ; it works without membranes or valves, and without interfer- ing with the steadiness of the light ; it is cheaper than the common gas-me- ter, and IS not subject to the great irregularities of the latter from variations m the water-hne. But, unfortunately for the Eiccuracy of the registrations of this instrument, the temperature of a gas-flame is not proportional to its light : as a measurer of the temperature of the flame, and also of the light of a gas-flame if gas of the same quality is always used, it might probably be made to aflord very accurate indications, but there is reason to doubt its accu- racy as a measurer of the light of gas of varying quality. Taking the average, however, of a periodical consumption, it may probably be made as accurate as most other meters. A modification of the ordinary meter has been contrived by Mr. Lowe, by which all pressure of the gasometer may be dispensed with. The chief' pe- culiarity in its construction is, that it possesses the action both of a suction- pump and a forcing-pump ; by the former it draws the gas from the service- main, without assistance from the gasometer, and by the latter it emits the gas for combustion. In the place of the water in which the drum of the common meter revolves, a solucion of caustic alkali is substituted, which does not freeze as readily as.water, and, moreover, serves to separate from the gas any sulphuretted hydrogen, carbonic acid, and sulphurous acid yet remaining. A large meter, called the station meter, is placed at the gas-works between the purifier and the gasometers, to ascertain at pleasure the quantity of gas made during any given period, so that the weekly, monthly, and annual pro- duction can be compared with the quantities registered by the meters of the consumers. Naphthalized Gas. — One of the most important of the. late improvements in gas illumination is Mr. Lowe's process for naphthalizing gas, or for impregna- ting ordinary coal-gas with the vapor of naphtha (pages 24 and 38 ) almost immediately before it issues from the burner. To efi'ect this, the coal-gas is passed either through some porous substance, as sponge or pumice-stone satu- rated with naphtha, or else over surfaces of that liquid contained in shallow trays. For the first method a rectangular box is employed, called the naph- tha-box, made of tm-plate or other suitable material, divided into two com- partments by a vertical partition in the middle, but which does not quite reach to the bottoin of the box. Each compartment contains a series of shelves formed of wire gratings, on which are placed strata of sponge or pumice- stone saturated with naphtha. The gas enters the box by an opening in the end at top, passes down through the several shelves of one compartment, then under the partition and up through the shelves of the other compart- ment, escaping from the box through an opening corresponding to that at which it entered. The apparatus employed to saturate the gas with vapor, by passing it over surfaces of the liquid, is equally simple. A rectangular box is fitted up with five or six shallow trays to contain the naphtha, placed one over the other, Near the end of each tray is a slit or aperture extending across the whole breadth of the tray, and furnished with sides rising to about half the depth of the tray. These apertures, which are placed alternately at opposite ends of contiguous trays, answer the purpose of waste-pipes to conduct the naph- tha from one tray to that next below it, when the liquid in the former rises higher than the side of the opening. The naphtha is poured by a funnel into the uppermost tray, which it fills to the top of the waste aperture, and then, falling into the trays below, fills them also in succession. *When the naph- tha issues from a small stop-cock at the bottom of the box, a sufficient quan- tity has been introduced. The gas enters the box at bottom from the meter, and, passing upward through the several apertures, is exposed to the surface 62 GAS ILLUMINATION. of the naphtha m each tray successively. By the time it reaches the top, it is thoroughly saturated with the vapor, and is then emitted for combustion. The latter plan is more convenient than the former in one respect, namely, that it does not require so frequent replenishing with naphtha. A thousand cubic feet of gas absorbs about a gallon of naphtha. The increase in the illuminating power of coal-gas, by being impregnated with naphtha is very considerable. A jet of hydrogen gas, which burns, when pure, with a pale blue flame hardly visible in the direct solar rays, gives a brilliant flame if the gas is passed through naphtha previous to being ignited. A good flame may be obtained even by impregnating common air, moderately warm (as the breath), with naphtha vapor. It has been estimated that one thousand cubic feet of naphthalized gas is equal in illuminating power to two thousand feet of common gas. If such is the case, the saving in this process amounts to twenty-five per cent., taking the cost of a thousand feet of gas at nine shillings. The expense of the naphthalized gas is — s. d. 1000 cubic feet of gas 9 o 1 gal. of naphtha 3 6 License for using the process per 1,000 feet 1 0 Cost of naphthalized gas equal to 2,000 feet of common gas 13 6 Saving 4s. 6d., or 25 per cent. But it is doubtful whether the illuminating power of the gas is so much as doubled ; according to another estimate, which seems nearer the truth, the savmg is about 15 per cent., reckoning the common gas to be burned in the most advantageous manner. The naphthalizing box, of the construction first described, is made subser- vient to the separation of any traces of sulphuretted hydrogen and carbonic acid which may have escaped the ordinary purifying processes. To this end the sponge or pumice-stone in the first compartment through which the gas passes is saturated with caustic potash, or caustic soda ; the shelves of the other compartment containing naphtha as usual. The small quantity of am- moniacal gas, which coal-gas purified in the ordinary manner generally con- tains, not only deteriorates slightly the illuminating power of the gas, but is injurious to the pipes. To separate this, a third compartment is given to the naphthahzmg box ; the porous material on the shelves of which contains di- lute sulphuric, muriatic, or other suitable acid. The metallic partitions and sides of the box may be protected from the acid by a covering of a mixture of bees-wax and tallow. In a box of three corttpartments, the first may contain sulphuric acid, the second caustic soda, and the third naphtha. As the tar produced in the distillation of coal may be regarded as a kind of ^'^termediate product in the conversion of coal into gas, its formation is at- tended, therefore, with the loss of a proportion of gas. Many contrivances have been suggested to reduce the amount of the product of tar, or to convert the tar into gas, by exposing the mixture as it issues from the retort to the turther action of heat. In 1835, Mr. John Malam, of Hull, obtained a patent lor the use of a second retort, or "regenerator," as termed by the patentee, into which the gas and tar vanor are passed before being conducted into the hydraulic main. The regenerator is a cylindrical vessel, like a retort, but composed of two tubes, one within the other, furnished with mouth-pieces, and arranged as a retort. The mixture of gas and vapors passes from the re- tort by a tube into the interior tube of the regenerator through a prolongation or mouth-piece at one end, passes into the other end of the tube, which is open and then escapes into the outer cylinder. After having traversed the Whole length of the latter, heated to redness, it is conducted to the hydraulic main. •' The quantity of tar obtained when the process is thus conducted is said to be only one third of the ordinary product ; the remaining two thirds being PRESERVATION OF WOOD. converted into gas. According to some experiments by Mr. Peckston, the average production of gas, when Mr. Malam's regenerator is made use of, is 12,500 cubic feet per ton of coals. The quality of the gas js not deteriorated, as might at first be supposed, but is improved ; the average specific gravity of the gas obtained by Mr. Peckston being 569. It is stated that the quantity of coal required for charging the retorts, and also of fuel for heating them, may be reduced 25 per cent. The Marquis Montaubon, and Messrs. Lowe and Kirkham, have also obtained patents for apparatus by which the greater portion of the tar is converted into gas, similar in principle to Mr. Malam's regenerator. [For some valuable suggestions which the Editor has received in this arti- ticle, he is greatly indebted to Mr. John Leigh, of Manchester, the chemical director of the gas-works of that town.] PRESERVATION OF WOOD. •i i. Properties and Composition of Wood. —II. Nature and Causes of Decay of Wood.— III. Pre- servative Materials.— IV. Modes of Applying Preservative Materials.— V. Other Effects of the Impregnation of Foreign Substances. The changes to which wood is liable under certain circumstances, known as rot and decay, are strictly chemical changes, and can only be properly un- derstood and guarded against by their chemical investigation. When wood is exposed to the simultaneous influence of water and air, it often loses all its tenacity, becoming pulverulent and at the same time darker in color. Tf a piece of wood is examined which has lain for some time in a damp situation, its surface being partially protected by paint or varnish, it is found that the parts which are unprotected have become corroded, soft to the touch, and probably, in great part, detached from the mass. For some time after the decay is commenced, the protected parts remain sound ; but, if the decayed portions are not re.moved, the entire piece becomes at length con- verted into a brown mass, which falls to a coarse powder when touched. The decomposition of woody fibre may take place in at least two condi- tions, namely, in the moist state subject to the free access of air, and under the surface of water, where the air obtains access only by being dissolved in the water ; the products of the decomposition in the two conditions are dif- ferent. When the access of air is limited, the decayed part does not acquire a brown color, but becomes grayish-white, and a matter soluble in water is produced during the decay, the nature of which has not been minutely inves- tigated. If the wood is freely exposed to the air, it may suffer another kind of de- composition, known as the dry-rot, by which it is rendered brittle, and has its cohesion completely destroyed. If absolutely dry, the wood is not subject to this disease, but it is capable of absorbing sufficient moisture from the air to continue the decomposition when once commenced. In damp and ill-ven- tilated situations the dry-rot produces the most serious damage, causing the destruction, in a few years, of entire buildings and ships. But though favored by a close and damp atmosphere, it may occur where the ventilation is per- fect and the atmosphere in its usual state of humidity. Dry-rot has been commonly attributed to the attacks of fungi ; the disinte- gration being effected partly by the introduction of their filamentous spawn between the Avoody fibres, and partly by the moisture they are the means of conveying to the interior of the wood. In most cases of dry-rot, fungi are certainly present, but often not till some time after the commencement of the disease ; in a few cases, however, fungi never make their appearance. Al- though, therefore, they may be intimately concerned in the rapid propagation 64 PRESERVATION OF WOOD. of the disease when once commenced, they do not appear to be its orieinal cause. ° That the decay of wood, once dried, is in all cases produced by an exter- nal cause, is evident from the circumstance that if the surface of the dried wood IS completely covered with a varnish impermeable to the air, decompo- sition IS effectually prevented. Under the surface of water, if putrefying or- game matter is absent, wood seems also to be able to resist decomposition for an indefinite time, and in dry air it may be kept for thousands of years without undergoing any sensible change. In order to examine minutely into the means of guarding against the decay of wood. It will be found convenient to consider, in the first place, the char- acters and composition of wood in a healthy state, and afterward, the chem- ical changes which take place in the processes of decay. § I. PROPERTIES AND COMPOSITION OF WOOD. _ The function of the woody tissue of plants, in a physiological point of view IS to support the various deciduous organs for digestion, respiration, &c , being m this respect similar to that of bones in animals ; to receive certain secre- tions, and to contain the sustenance necessary for the newly-forming parts be- fore a more direct communication is established between "them and the soil 1 hough perfectly homogeneous to the naked eye, woody tissue is perceived when examined by the microscope, to be composed of long, thin, transparent' tough, membranous tubes, which seem to be originally derived, like all other solid parts of plants, from a simple rounded cell. Woody tissue, though the chief and essential, is not the only constituent of wood or timber. Interspersed between the tubes which form the woody tissue, is the cellular tissue which consists of cells or cavities closed on all sides, formed of a delicate and 'usually transparent membrane. Cellular tissue is more abundant in herbs than in trees, and decreases m proportion as the plant attains maturity. In exooenous trees it forms perpendicular plates radiating from the pith, as a centre, to the bark. The cross section of a first year's stem of an exogen (lo which class belong al- most all trees producing woods employed for mechanical purposes in this coun- try ) presents, io, in the centre, pith, composed of cellular tissue : 2", around the pith a layer composed principally of woody tissue ; 3°, around the woody tis- sue a layer of bark (composed of several similar layers) ; and, lastly, 4o, from the pith to the exterior of the wood lines of cellular tissues, which are sections of the radiating plates above referred to, distinguished as medullary rays, me- dullary processes, or medullary plates. These are often imperceptible by the naked eye, but always present. At the commencement of the second year's growth, a spontaneous separation of the layer of wood and the innermost layer of the bark or Itber takes place, and the intervening space becomes occupied with a viscid gelatinous liquid, ^ the cambium. In this liquid are deposited elongated cells or tubes, which form the woody tissue of another layer of wood immediately surround- ing the first year's layer, and the principal part of the cellular tissue that con- nected the wood and the liber becomes arranged in perpendicular plates, forming continuations of the medullary rays of the first year. This second year s layer of wood is quite similar to that formed in the first year, to which 1 1 IS firmly attached. The increase of wood goes on in this manner, circle around circle, or rather zone upon zone, each year ; so that, with young trees, where the line of distinction between the several layers is easily perceived, the age of the tree may be estimated by the number of layers. Besides the external ring of wood, there is also formed yearly an internal ring of bark (liber), which at length becomes the external ring, those rings previously exterior to it hav- ing decayed as the stem increases in diameter. The name of the class of trees havmg this r^ner of growth, or exogens, has reference to the external aug- mentations (fl^woddy matter ; unlike endogens, in which the wood is formed br successive augmt^ntations from the interior. PROPERTIES AND COMPOSITION OF WOOD. 65 The length of the medullary plates varies from a quarter of an inch or less as m the sycamore and maple, to several inches, as in the oak. When viewed by the microscope with a low power, they present a granular appearance • but with a high power, a cellular structure similar to that of the pith is percepti- ble, ihe light and glossy appearance of polished vertical pieces of several kmds ot wood, known among carpenters by the term silver-grain, or flower of wood, IS produced bv the exposure of the medullary plates. The tubes which form the woody tissue vary in diameter from ^y^^, to part of an inch. They taper acutely at each end, and do not appear to have any direct commumcation with each other ; no pores are perceptible in their sides. They are very tough, and usually cylindrical, but have sometimes been observed in a prismatic form. The reason why the yearly increments of woody matter in exogens are de- hned (they being in juxtaposition and composed of a similar structure), is, that the woody tissue formed toward the close of the growing season is denser and more compact than that formed at the commencement. If, however, through an equable climate or any other cause, the tissue formed at the close of the befw^PnT"" 'T'-" ^""'^^^^ '^'^ commencement, no distinction rmltlc^^ ^'f^ increments will be perceptible ; in the wood of tropical countries, the absence of concentric circles is a very frequent occurrence. in trees of less than eight or ten years old, there is usually no perceptible difference (excepting the lines of demarcation) between the several laj^Vs of woody tissue ; but, after the lapse of ten or twelve years, the two or three in- DroTer]7.T. llT^ considerably hardened, and pass into the state of -timber properly so called. The interior hardened layers are distinguished as the IZS '''^"-^^o"^' and the softer exterior layers as the alburnum and .K-'?^ I^r. ^( tubes of the woody tissue forming the alburnum are-v«rv thm, and hardly any solid matter is contained in the interior of the tubes bat> merely sap - the alburnum being the principal channel through which the sap ' IS conveyed from the roots to the leaves. The alburnum is always lighter in CO or than the duramen, and, having little solidity and power o7adhfsion, "s readily susceptible ot disintegration and decomposition on which account it ^ IS always separated from the heartwood when the timber is worked up The superior hardness and durability of the heartwood is owing to the thickening Skri! ^[ the deposition of various solid matters ; as Ef fannin wifh''^ tr'!f '^'^f,^^^ ^^lls, and resins, insoluble compounds of tanmn with matters derived from the sap, coloring matters, &c., which im- fulTZ to^different species of woods • the sapwood has nearTy the same appearance in all trees. ' takp.'nwV'^^''^f' ""^^ ""^^ conversion of sapwood into heartwood rhTlrl f '° "'V'"' ''^ P^P^^"" ^""^ ^illo^^' very sl>3wly, or not at all. wooarrif u^^'! ^^J-'i''' technically called white- Tnv A durability of that of the former, and is unfit for any but temporary uses. r^AiT f«'^"iation of heartwood is once commenced, the number of layers ot sapwood usually continues the same at all stages of the growth of the tree • Sr.f l.r\^"^'' of heartwood is produced annually' The heartwood itselt IS not of the same density throughout ; its interior layers gradually attain t-Z fr i^""'"'^' "^^''^ f acquired by the other lay'ers iS yearly succes^ tirL 1 '''''^ reinained for some time at the maximum density, the in- wIX. ^^!f "^^^"5^' becoming lighter in color, softer, weaker, and readily altered by the action of decomposing agents.* Ac*cord1frtoThe?Lorvo^^^^^^ "/"^eming the origin of woody tissues, sidered a! roots of Ihl F^^jj"^^^^^ ^1 ^'"dley and otliers, wood may be con- length reach the extreme rools of thP trir'^'p ".^ ''"^"^ard through the cambium, and at which entirely surrounds thP wn°H ' close lateral adherence they form a layer the new wood Consiste^?!^ w^fh H^it t. P'*'"''.'"^ y^"""' and becomes itself a component part^f proportional to the amoun o^^^^^^^ amount of wood is generally observed to be tree are more vLrous tha^ on tL n^h leaves and branches whicli grow on one side of a heat),thetWctaess of^L laverrof w^^ ^^'f ""^^ ^.^PP^? exposure to more light and /, luo uucKness ol the layers of wood is greater on the side with vigorous leaves and branchet 66 PRESERVATION OF WOOD. Such is the structure and manner of growth of exogens. With reference to the growth of the other great class of trees, endogens, which includes palms, bamboos, grasses, &c., it will be sufficient for our purpose merely to mention that it is essentially different from that of exogens, the new woody matter being first developed toward the centre of the trunk ; whence the name of the class, Endogens are not possessed of a well-defined cylindrical column of pith, nor of medullary rays : the densest part of their section is near the sur- face, instead of being near the centre, as in the heartwood of exogens. Wood is unfit to be used for building in the state in which it is felled. The tissues, being then distended with sap, experience a contraction when the water in the sap evaporates ; and, if the recently-felled wood is placed in a confined situation, the humid nitrogenized matter in the sap rapidly decom- poses, and induces the decomposition or decay of the wood. To avoid these inconveniences, the wood, before being worked up, is care- fully dried or " seasoned," by which it is reduced in bulk across the grain, and the nitrogenized matter of the sap is rendered less susceptible of decoinposi- tion. The ordinary process of seasoning wood consists in merely exposing it to a free current of air, the wood being either in the form of planks or logs, or in smaller pieces of about the sizes and forms to which they will afterward be reduced. If the pieces are thin, twelve months' exposure in a dry situation with a free current of air will complete their desiccation to the extent required ; but thick pieces often require several years. In general, the closer the grain, the longer is the time required ; thus' a large piece of oak is not thoroughly seasoned in less than eight or ten years. The exposure ought to be continued until the wood ceases to lose weight from evaporation, but this would require twice the period usually allowed for the process. The seasoning of wood is said to be effected better and more rapidly by pre- viously washing out or diluting the sap, which may be accomplished by ex- posing the wood for some weeks to running water, or by boiling the wood in water. A quantity of the soluble matter in the sap is brought to the surface when the wood is exposed to the action of steam, as in the operation for fa- cilitating the bending of oak and other timbers for ship-building, &:c. A patent for an improved method of seasoning timber was obtained in 1825 by Mr. J. Langton, of Lincolnshire, which consists in drying the wood in a vacuum, or in a highly-rarefied atmosphere. The timbers are placed vertically in an air-tight cast-iron cylinder connected with an exhausting- pump, and, when exhausted of its air, the cylinder is heated by means of a vapor-bath. The moisture given off from the wood is condensed in an air- tight refrigerator, so as to prevent its reabsorption. The amount of contraction which takes place through desiccation is very different in different woods, being usually greatest in soft woods. In teak- wood the contraction is scarcely perceptible ; in some soft woods it amounts to half an inch in the foot. The entire proportion of water in green woods varies from 38 to 45 per cent., according to the species and age of the wood ; but the whole of the water can not be removed by drying in the air at common temperatures, however long the desiccation may be continued. Woods from the mulberry -tree, hazel-tree, and linden-tree, cut from branches of mean size at the close of autumn, de- creased in weight in six months in the following proportions: mulberry, 26 per cent. ; hazel, 33 per cent. ; and linden, 40 per cent. After being dried during twelve months, wood generally retains from one fifth to one fourth of its weight of water. A beam of oak-wood, kept for a century in a dry situation, was than on the otlier. When the growth of the branches is equal on all sides, the thickness of the layers of wood is also usually equal 8ill around. But leaves are not the only agents by which the woody tissue is developed, for many parts of plants, and some whole orders (as cactaceae), possess no leaves, and yet develop woody tissue. It has also been proved, by Dr. Lankester, that trees from the stems of which the bark is removed at the spring of the year, will present new woody- tissue between the bark and wood at the end of the year. Other circumstances may also be ad- duced in opposition to the theory which supposes buds to be the only agents concerned in the pro- duction of wood. The recent researches of Dr. Schleiden go far to prove that the original cells, which become elongated into tubes forming woody tissue, are developed in the same manner as the cells of the cellular tissue ; that is, as excrescences proceeding from particles (cytoblasts) i» the sides of anteriorly-formed cells PROPERTIES AND COMPOSITION OF WOOD. 67 found by Count Rumford to lose 9 per cent, of its weight when dried at a high temperature. According to M. Karsten, oak-shavings perfectly desiccated in the air lose 10-3 per cent, of water when heated at 212° ; but even at that temperature they retain a sensible quantity of water capable of being expelled at higher temperatures. The Avoods of the willow and birch, in a state of fine powder, and freed from sap by digestion in boiling water, retain 14-5 per cent, of water after desiccation in the air, for the expulsion of the whole of which the wood must be heated gradually to a temperature near 310°Fahr. (Prout.) When wood, rendered perfectly dry by the aid of heat, is exposed at coin- «7ion temperatures to the atmosphere in its ordinary state of humidity, it re- absorbs a certain proportion of water, varying according to the compactness of the wood and to the quantity of deliquescent saline matters present. In a dry room without a fire, the quantity absorbed usually amoun^g to about 10 per cent. If covered with a resinous varnish, dry wood does not absorb atmo- spheric humidity. In its ordinary state, wood is a conductor of electricity, from the presence of saline solutions ; when rendered perfectly dry by the aid of heat, it is a non- conductor, but its conducting power returns upon the absorption of moisture, which takes place on re-exposure to the air. Although nearly all kinds of wood float on water, yet the density of the true woody fibre is considerably greater than that of water. The apparent light- ness of wood is owing to the presence of a large quantity of air in the pores of the wood, which is not displaced by water at common atmospheric pressure without a very long digestion. But if a piece of wood is placed on water in (he receiver of an air-pump, and a vacuum made, as the air in the pores of the wood is Avithdrawn, water enters the pores, and the wood sinks. According to Count Rumford, the specific gravity of the true woody fibre is much the same for all kinds of woods, varying only between 1-46, which is that of fir and maple, and 1-53, which is that of oak and beech. The specific gravity of the different kinds of woods in their ordinary state must therefore indicate their porosity, or the proportion of air within their pore§. To take the specific gravity of wood in water for this purpose, the absorption of water by the wood should be prevented by applying to the surface of the wood a resinous varnish of the same density as water, which may be obtained by a mixture in certain proportions of wax and resin.* • The first column in the following table exhibits the specific gravity of different woods as adopted by the Annuaire du Bureau des Longitudes ; the second column contains the results obtained by M. Karmarsch : — I. II. Box 942 Plum-tree 872 Hawthorn 871 Beech 852 Ash 845 670 Yew 807 744 Elm 800 568 Birch , 738 Apple 733 734 Pear 732 Yoke-elm... , 728 Orange-tree 705 Walnut-tree 660 Pine 657 763 Maple 645 Linden-tree 604 559 Cypress 598 Cedar 561 Horse-chestnut 551 Alder 538 White poplar 529 Common poplar 383 387 Cork 240 * The specific gravity of wax is 0.967, and that of resin 1.07a 68 PRESERVATION OF WOOD. The same kind of wood varies considerably in density according to the soil on which the tree is grown, the climate, the age of the wood, and other circumstances. According to Rumford, the specific gravity of a piece of wood taken from the trunk of an oak in active growth is 961 ; that of billets of oak, cut and dried for a few years, is 8S3 ; that of a beam of oak, cut for at least six hundred years, was found to be 682 ; and that of the same wood when compleielv desiccated, 610. Several exotic' woods are considerably heavier than those kinds grown in Eu- rope : the wood of the guaiacurn officinale, for example, possesses the specific gravity 1263 ; the specific gravity of ebony is 1213. Probably the heaviest of all woods is that known by the name of the iron-bark wood, brought from New South Wales, the density of which is 1426. Its strength, compared with the English oak, was found by Mr. HoltzapflTel to be as 1557 is to 1000. The lightest of true woods known in this country is the CorUca, or Anona palus- 'ris, the density of which, according to Mr. Holtzapffel, is only 206. This wood resembles ash in color ; but is paler, finer, and softer. From three to six per cent, of exsiccated wood is composed of solid mat- ters derived from the evaporation of the sap, in which ihey were previously contained in a state of solution. These consist partly of saline matters, the proportion of Avhich varies in different woods from two parts in a thousand to two per cent. But by far the principal part of the residue of the evaporation of the sap is a substance termed vegetable albumen, which closely resembles animal albumen (while of egg) both in properties and composition. It c-on- tains nitrogen, and, like animal albumen, is exceedingly prone to decompo- sition. The use of this substance in the living plant is to lubricate the sides of the various vessels, being the same as that of the mucous membrane of animals. It will be seen in another part of this article that the decay of woody fibre is generally an induced effect of contact with vegetable albumen in a state of decomposition. Different woods vary very considerably in the proportion of albumen which they contain. ^ ■ r It has been lately shown, by M. Hartig, that a considerable quantity ot starch is deposited in the interior of the vessels of the wood, which is capable of being extracted by mechanical means. The proportion of starch is said to be greatest in the winter season. To procure starch from this source, it is recommended to reduce to powder the dried shavings of green wood, and to rub the powder with a quantity of water. After standing for five or ten min- utes, the ligneous powder may be separated by decanting the liquid, from which the starch is gradually deposited. Like all other varieties of starch, this substance is colored intensely blue by iodine, and, when examined by the microscope, is perceived to be composed of spherical granules. The taste of its solution in warm water is slightly astringent. By digesting the sawings of wood or the fibre of lint and cotton, succes- sively in ether, alcohol, water, a diluted acid, and a diluted caustic alkali, so as to separate all the matters soluble in these liquids, without continuing the action of the acid and alkali so long as to alter essentially the constitution of the wood, there remains behind a white, spongy, pulverulent substance, which is the basis of the wood, or lignin, constituting from 95 to 97 per cent, ol all kinds of desiccated wood. . Lignin is possessed of certain physical and chemical properties, whicn am- ply distinguish it from every other vegetable principle. These properties are always the same, if the lignin is prepared as above, however great the diner- ence which may exist between the plants, or parts of plants, from which it is prepared. White unsized paper, digested in dilute hydrochloric acid to re- move the earthy matters which it contains, and then Avashed with distilled water, affords a very pure form of lignin. In a state of purity, lignin possesses the following properties :— It is white, tasteless, and inodorous, and presents, when examined by the microscope, a cellular or tubular structure. It is considerably heavier than water, but usually floats on that liquid in consequence of containing air im- prisoned within its cells or tubes. It is insoluble in water, alcohol, ether, PROPERTIES AND COMPOSITION OF WOOD. 69 fixed and volatile oils, diluted alkalies and diluted acids. It dissolves in the most highly concentrated nitric acid, without producing the decomposition of the acid ; and, if the solution is immediately diluted with water, it fives a white pulverulent precipitate, which is a neutral substance highly combusti- ble, insoluble in water, containing, according to Robiquet, the elements of nitric acid. Weaker nitric acid converts it into oxalic acid, suberic acid, and other products. When fused with a caustic alkali, lignin is converted into either ulmic acid or oxalic acid, according to the proportion of alkali and the temperature which is applied. When lignin is mixed cautiously with concentrated sulphuric acid, so as to avoid elevation of temperature, it is converted partly into dextrin, a gummy substance which is produced by the action of dilute acids and other agents on starch. A portion of the sulphuric acid unites at the same time with some of the ligneous matter to form a compound which has received the names of lignin-sulphuric acid, and ve geto-sulphuric acid, which forms soluble salts with barytes and oxide of lead. When the above mixture of concentrated sul- phuric acid and dextrin is diluted Avith water and boiled, the dextrin passes into the state of starch sugar. To prepare starch sugar from this source, six parts^f clean hempen or lin- en cloth, divided into small pieces, is intimately mix^d with eight and a half parts of concentrated sulphuric acid, added in very small quantities. In the course of half an hour, when the cloth has become converted into a brown viscous mass, entirely soluble in cold water, sufficient water is added to dis- solve the mass, and the mixture is boiled for eight or ten hours, fresh water being added from time to time to replace that which is expelled by evapora- tion. The saccharification is then complete, and the free sulphuric in the so- lution is separated by the addition of an excess of chalk, which becomes con- verted into the insoluble sulphate of lime. The filtered liquid leaves a residue of starch sugar on evaporation. According to M. Braconnot, twenty parts of lignin afford about twenty-three parts of sugar, Lignin resembles starch not only in being convertible into dextrin and sugar by the action of acids, but also in being converted into dextrin (or an analo- gous substance) by mere torrefaction. The identity in the nature of the ligneous matter derived from all kinds of trees is evidenced not only by its chcnical properties, but by its analysis. The composition of washed and dried wood from the oak and beech was found by MM. Thenard and Gay-Lussac to be the following :— Carbon 51-45 Hydrogen 5- 82 ) Oxygen 42-73 ( = "^^^er 48-55 100-00 Analyses of washed and dried wood from the box and willow afforded Dr. Prout similar results. / From these and other anaWes the formula Cgg O22 has been assigned to pure lignin. / According to the more r/cent researches of M. Payen, the lignin of wood is not a homogeneous substance, but a mixture of two principles, which he had succeeded in separating. One of these is the primitive woody tissue, which has the same composition as starch (0,2 H,o Ojo), and is named cellulose by M. Payen. The other principle is the true ligneous matter, and is contained in the interior of the cells in a proportion varying according to the nature of the wood and the age of the tree. It forms the principal part of the solid matter which gives durability and hardness to the heartwood. The separation of the true lignin (matiere incrustante) from the cellulose was effected by M. Payen by the agency of highly concentrated nitric acid, which dissolves lig- nin, but leaves the cellulose without alteration. The remaining cellulose is soluble in concentrated sulphuric acid without being blackened. The true iigoin is considered by M. Payen to contain more hydrogen than is required 70 PRESERVATION OF WOOD. to form water with the oxygen present ; that from hemp, lint, straw, and lin- en cloth corresponded in composition with the formula C35 H24 Oao- When wood is subjected to destructive distillation in close vessels, a great variety of volatile products is disengaged, comprising water, acetic acid, a black mass known as wood-tar (containing several peculiar combustible liquids and solids), several oily and spirituous substances, carbonic oxide gas. and gaseous compounds of carbon and hydrogen. The higher the temperature at which the distillation is conducted, the larger is the proportion of gaseous matters among the products. A residue of charcoal of the same shape as the original pieces of wood, but less in size, is found in the retort, the weight ol which varies from 16 to 28 per cent, of the weight of the wood. _ The flame of burning wood proceeds from the combustion of the same kind of gaseous matters as are given off" when the wood is subjected to destructive distillation in close vessels. As the proportion of these products is partly de- pendant on the temperature at which the distillation is conducted, it follows that, to obtain the largest possible flame, the wood should be dry, in order to avoid loss of heat by the evaporation of the water, and in small pieces which may be quickly heated to their centre and applied to the fire in small quanti- ties at a time. If the temperature necessary for active combustion is main- tained, and sufficient ah has access, the combustion of the wood is complete ; the only residue being a small quantity of white ash derived from the sahne and earthy matters formeily contained m the sap. The carbon of the wood in this case is entirely converted into carbonic acid, and the hydrogen into water, by combining with tl\e oxygen of the air and of the wood. But it is difficult to unite at all times the conditions necessary for perfect combustion, namely, a high temperature and sufficient air ; the ■ combustion or oxidation of the volatile products is hence often incompletely effected, and smoke • The soot which is deposited o\i a cold body from the smoke of burning wood has been analyzed by M. Braconnot, wi\h the following results ;— A nitrogenized carbonaceous ipatter insoluble in alcohol M'W Ulmin.! \ ^^'^ An acrid and bitter principle . .\ Water • ^^'^^ Carbonaceous matter insoluble itt alkalies 3-85 Acetate of potash ». Acetate of ammonia \ Acetate of lime \ Acetate of magnesia •> \ Acetate of iron \ Chloride of potassium , Sulphate of lime • Ferruginous phosphate of lime Carbonate of lime .Q5 Silica 100-00 i^ampblack differs from common soot in being more completely carbonized. Ac- cording to the analysis of M. Braconnot, the compoiition of lampblack from wood la the following : — ^g.j ca'^^o" ;;;;;; s-o Water... 53 Kesin j.y Bitumen .g Ulmin ,M Sulphate of potash „ _ Sulphate of ammonia g Sulphate of lime.. Chloride of potassium. airace. Ferruginous phosphate of lime * Quartzy sand 100-0 4, PROPERTIES AND COMPOSITION OF WOOD. 71 (wkich consists chiefly of solid particles of a carbonaceous substance) is pro- ducted. Compact woods burn only at the surface ; the volatile combustible products which produce flame are quickly disengaged, and a mass of charcoal remams which burns away slowly without the production of flame or at least of the yellow flame which is perceived at the commencement 'of the combustion. Light porous woods, which freely admit air to their interior bum more rapidly than compact woods, and aff^ord a yeUow flame almost the whole time of their combustion, leaving a very small residue of char- coal. With a view of determining the heating power of diflj-erent kinds of wood m a state ot combustion, a set of experiments was performed by MM Peter- son and Schodler to ascertain the quantity of oxygen required for the com- bustion of a given weight of the different woods. If the woods are equaUy dry, the amount of heat disengaged by the combustion is very nearlv propor- S Vl'^^'Xf^'"'^^'''' ^^'''^ """^^ the combustible: The results obtained by MM. Peterson and Schodler are the following:— Names of trees. - , , , Oxygen required to bum „ 100 parts of each. 1 ila Auropea, kme. 140-523 Ulmus suberosa, elm * 1^Q'408 Pinus abies, fir . . . . , . [ . . . 138-377 Pinus larix, larch '....*!.".'!!.**!*.,.'! 138-082 Msculus hippocastanum, horse-chestnut !!'.'.!!".!!!".!'. 13S-002 Buxns sempervirens, box *.**.".' 137-315 Jlcer campestris, maple 1 '*.!*.'.".".!". 136-960 Pinus sylvestris, Scotch fir ..V........... ...... 136-931 Pinus picea, pitch pine . . . . . . . . 136-886 Populus nigra, black poplar 136-628 Pyrus communis, pear-tree 13.5-881 Juglans regia, walnut .'."...."!'..*.!!...." 135-690 Betula alnus, alder ".. '. *. ".! 133-959 Salix fragilis, willow ISS-QtI Quercus robur, oak . V. 133-472 Pyrus mulus, apple-tree ".!.".'.!.!.'.!!.......*..! 133-340 Fraxinus excelsior, ash iqq osi Betula alba, birch ISs'Sq Prunus cerasus, cherry-tree 133.130 Robinea pseudacacia, acacia 132-543 Fagus sylvatica, white beech IS^-'? 12 Prunus domestica, plum J32.088 F agus sylvatica, red beech 130-834 Biospyros ebenum, ebonj ,...[ 128-178 Heat is dissipated from a body in a state of ordinary combustion in two v^ays entirely distinct from each other: l^by the ascending cu ent of and gases from the combustible; and, 2°, by radiation in all directions both from the surface of the burning body and from the flame. M. Met has ascertamed by experiment that the radiating power of burning wood is not the same for diff-erent kinds of wood ; and that for the same kind it is^rea^er when the wood is in large than in small masses, because the radiatin/power of the charred surface of the wood is much greater than the radia iSf Sowe of flame. If the wood is m very small pieces, the amount of heat fadiaTed s very nearly the same for all kinds of wood, and is equal to one Sird of in I*!f r^""^'*^ f "^^"^ "^^^^.^ ^^"'^^"^ the combustible matter SfrlrentwoorP r'h^Vfr""''^. k/"/ ""'^ considerabl^from aitterent woods. The followmg table shows the quantity which remains after the^combustion and mcmeration of 1000 parts of severd di^ereTkSds of 72 PRESERVATION OF WOOD. Spindle 4 Ash 4 Filbert 4 Box 3'6 Poplar 2 Cork 2 Maple 2 Oak (faggots) 22 Ebony 16 Mahogany 16 Aspen 6 Pine 4 Birch 4 Fir 4 Barked oak 4 These ashes are composed of alkaline salts soluble in water, and earthy matters insoluble in water. The soluble alkaline salts consist of carbonates and sulphates of potash and soda, chlorides of potassium and sodium, aiid a little silicate of potash. The insoluble earthy matters are composed of lime or carbonate of lime, according to the temperature at which the incineration is performed, phosphate of lime, phosphate of magnesia, phosphate of iron, oxide of manganese, and silica. The proportions of ash given in the prece- ding table do not represent the actual quantities of saline matter in the differ- ent woods ; as the greater part of the potash, soda, and lime, exists in the woods in combination with vegetable acids, as tartaric, oxalic, acetic, &c., which become destroyed by the combustion. One of the products of the decomposi- tion of the vegetable acids is carbonic acid, part of which combines with the bases formerly united to the vegetable acids. This is the only source of the carbonic acid in the carbonates of potash and soda found in the ash ; as the wood before calcination does not contain a trace of an alkaline carbonate. The results given in the preceding table are those obtained when the ash is cal- cined at a full white heat, by which the carbonate of lime becomes converted into quick-linae. When thus calcined, the ash weighs nearly one third less than it does if the residue of the combustion is simply incinerated at a red heat, until the charcoal is completely consumed. The relative proportion of ash obtained from the young and old wood of a few different kinds of trees is shown in the following table of the results of some experiments by M. Karsten : — From young oak-wood 15 parts of ash in 1,000 of wood. « old " 11 « " young red beech-wood (rothbuchenholz) 37-5 « " old " « 40 « « young white beech-wood (weissbuchenholz) . 32 « « old " 35 «e " young alder-wood 35 « " old " 40 « " young birch-wood 25 " " old " 30 « " young red pine (fichtenholz) 15 « "old " « 15 « " young white pine (tannenholz) 22*5 ** "old " " 25 «« " young pitch pine (kiefcrnholz) 12 *' "old " « 15 « The difference in the composition of the ash derived from the wood of dif- ferent kinds of trees is not very considerable. The portion soluble in water comprises from one eighth to one fourth of the entire ash. Analyses of the uisoluble portions of the ashes of oak-wood and beech-wood afforded the fol- lowing results (M. Berthier) : — From oak-wood. From beech-wood. Lime, as carbonate and phosphate 53-2 42*6 Magnesia — 7.O Oxide of iron — I.5 Oxide of manganese 9-0 4-5 Carbonic acid (as carbonate of lime) 24*4 32-9 Phosphoric acid (as phosphate of lime) 7-0 5-7 Silica 6-4 5-8 100-0 1000 . NATURE AND CAUSES OF THE DECAY OF WOOD. 73 Tke soluble portions of the same ashes were found to be composed of Potash and soda °65-r°^' ""'""^ I'^f'^'"'^ Carbonic acid 24-3 22*4 Sulphuric acid ' * * ' jq.q y.g Muriatic acid .c Silica '.'.'.'.".".*.".'.'.".'.".'. _ I'.Q 100-0 100-0 § 11. NATURE AND CAUSES OF THE DECAY OF WOOD. By referring to the observations contained in the preceding section on the structure and composition of wood in a healthy state, it will be perceived that accordmg to the analyses of MM. Gav-Lussac and Thenardf and Dr. f ront, pure woody fibre may be considered to contain carbon united with the elements of water ; but that, besides the pure fibre, wood contains, in its or- dinary state, from three to five per cent, of soluble matter, of which, nitrogen lorms an essential constituent. ^ It appears from the experiments of De Saussure that the decay of wood?/ fibre _ IS essentially a process of oxidation. On exposing moist wood to oxygen gas, It was found that, for every volume of oxygen absorbed by the wood, one volume of carbonic acid gas was disengaged. As carbonic acid gas contains Its own volume of oxygen gas, the result might seem to be merely a separatioiv of a portion of the carbon of the wood by a process of oxidation ot combustion at low temperatures. Such cases of slow oxidation have been distinguished by Liebig by the name of erernacausis, which is compounded from tpUa, by degrees, and Kavcn, burning. ^ r > : But the examination of the products of the action of oxygen on dry wood, and the analysis of the residuary mould or humus, show that wood loses by the process of slow combustion or erernacausis, besides carbon, a certain amount of its hydrogen and oxygen in the proportion to form water. On ex- posing 240 parts ol dry saw-dust of oak-wood to the action of oxygen gas, De baussure found that the oxygen became converted into the same volume of carbonic acid gas contaming 3 parts by weight of carbon. But the wood di- mmished m weight by 15 parts ; 12 other parts were therefore separated in the lorm ot oxygen and hydrogen. For the following considerati'ons on the nature of the decay of woody fibre I am indebted to Professor Liebig's valuable work entitled " Organic ChemisI ry applied to Agriculture and Physiology." In an agricultural point of view h.\ni?w-fl,^ ''^^ t Tl' importance as being the means of furnishing nl vin ^"^T \ °^ tl^e air, becomes a means of sup- plying the roots of plants with carbonic acid. ^ Notwithstanding the separation of carbon from wood during" the process of decay, m the form of carbonic acid, if the composition of the decaying wood IS examined at different stages in the process, it is found that the relative pro- portion of carbon m the diff-erent products augments as the decay advances, ihe weight of the hydrogen and oxygen, therefore, which are given off simul- taneously with the carbon, IS greater than the weight of the separated carbon. According to Gay-Lussac and Thenard, 100 parts of oak-wood dried at 212° from which all soluble matters had been separated by means of water and alcohol, contained ol-4o parts of carbon ; the remainder being hydrogen and wifr. ? % "^""l proportion as in water. A specimen of mouldered oak- wood, taken from the interior ot the trunk, of a chocolate-brown color, and re- tainmg the^structure of wood, was found by M. Meyer to contain 53-36 per norrinnl'" "'.^""^ ^^'^ hydrogen and oxygen, in the same pro- portions as exist in water. Another specimen of mouldered oak-wood, ki a Sip r,^ t""^ ' ^ ^^^^^ ^^""^ and easily reducible to J"' ^""T^ ^^^^ ^°"^ai^ 56-2 per cent, of carbon, and 4d 8 of hydrogen and oxygen in the usual proportions. The composition of 74 PRESERTATION OF WOOD, these substances in equivalents is represented by the following^ formulae, witb which the percentage composition, as obtained by analysis, closely agrees : — It appears from these data that, for each equivalent of carbon separated from the wood, there are also separated two equivalents of oxygen and two equiva- lents of hydrogen. The process is merely a case of slow combustion through the oxygen of the air, but it remains to be decided whethe? the carbon or the hydrogen of the wood unites with the oxygen absorbed from the air. One of these elements is doubtless oxidized by the air, the other unites m-ore inti- mately than before with the oxygen of the wood. If, as some suppose, the hydrogen and oxygen of the wood already exist in the state of water, the wood being a hydrate of carbon, there can be no doubt that the carbon is oxidized immediately by the air. But the characters of woody fibre favor the idea that its hydrogen and oxygen do not exist in the form of water ; for, were that the case, dry starch, sugar, and gum, must likewise be considered as hy- drates of carbon. And, if the hydre^en does not exist in woody fibre in the form of water, the direct oxidation of the carbon can not be considered as at all probable without rejecting all the facts established by experiment regarding- the process of combustion at low temperatures. (Liebig, Agricultural Chem- istry, p. 295, third edition.) If such were the case, it would be a combustion in which the carbon of the burning body constantly augmented, instead of being diminished. It may therefore be concluded that it is the hydrogen which is oxidized at the ex- pense of the oxygen of the air, while the carbonic acid is wholly formed from the elements of the wood. It is uncertain to what extent this decomposition of the wood may proceed under the ordinary influence of moisture and air, favored with warmth and light, but certainly not so far as to the entire separation of the hydrogen and oxygen ; for, with ihe increased proportion of carbon in the residuary humus,, its affinity for the remaining hydrogen increases, until at length it equals the affinity of the oxygen for the same element. Such are the changes which wood suffers when exposed in a humid state to an unlimited quantity of air. But when the air is entirely or partially exclu- ded, water still having access, the order of decomposition is considerably modi- fied. _ Carbonic acid is then evolved in the same manner as when air is freely admitted, but ihe hydrogen of the wood remains behind. Two analyses of the white decayed wood, obtained from the interior of the trunk of a dead oak which had been in contact with water, yielded, after having been dried at 212", Carbon..., 47-11 48-14 Hydrogen 6-31 6-06 Oxygen 45.3 1 44.43 Ashes 1-27 1.37 The mean of these numbers corresponds very nearly to the formula C33 Hj^ O24, which gives, by calculation, carbon 47-9, hydrogen 6-1, oxygen 46. By coinparing the formula with that assigned to woody fibre by Gay-Lussac and Thenard, it is seen that the elements of water become united with the wood, and a portion of the carbon of the wood is separated in the form of carbonic acid. The oxygen of the carbonic acid is derived partly from the wood and partly from other sources, particularly from free oxygen contained in solution in the water, and derived from the atmosphere. It is supposed by Liebig that in this, as in all other cases of putrefactive decomposition, the oxygen of the water itself assists in the formation of the carbonic acid. The above formula for mouldered oak is obtained by adding to the formula Fresh oak-wood, by Gay-Lussac and Thenard Humus from oak, by M. Meyer Humus from oak, by Dr. Will C36 H22 O28 C35 H20 O20 C34 H18 O18 100-00 100-00 NATURE AND CAUSES OF THE DECAY OF WOOD. 75 for pure woody fibre the elements of five equivalents of water, and three equivalents of oxygen, and subtracting therefrom three equivalents of carbonic acid. Woody fibre C36 H22 O22 5 eq. water _ H5 O5 3 eq. oxygen — — O3 ^ , „ C38 H27 O30 Deduct 3 eq. carbonic acid C3 Oe Mouldered oak C33 H27 O24 But the composition of mouldered wood varies according to the facility with which oxygen has access. A specimen of white mouldered beech-wood af- forded, on analysis, carbon 47-67, hydrogen 5-67, and oxygen 46-68, numbers which correspond to the formula C33 HiiO^i (Liebig). The decomposition which wood suffers in marshy soils, and under water in contact with decaying vegetable matter, the access of free oxygen being wholly prevented, is a case of putrefaction or transformation of the constituents of the wood into other forms of matter, differing from the preceding cases in the circumstance that the decomposition is not effected by the separation of one of the elements of the wood through the affinity of an external substance. In the cases already considered, the decomposition is partly effected through the affinity of oxygen for the hydrogen and carbon of the wood. When the wood is imbedded in marshy soils, the access of free oxygen is prevented by the wood being surrounded by attenuated decomposing vegetable matter, which has a more powerful affinity for oxygen than the denser wood. In such cases of transformation, the carbon of the wood is shared between the hydrogen and oxygen of the wood ; the carbon forming with hydrogen hght carburetted hydrogen or marsh-gas (CHa), and with oxygen, carbonic acid. A portion of the hydrogen and oxygen of the wood may probably unite to form water at the same time. The mouldy residue always contains a much larger relative proportion of carbon than previously existed in the wood. In assigning a cause for these transformations, it is not sufficient to ascribe them to the action of air and water. It is known that in dry air woody fibre may be preserved without decomposition for thousands of years ; and under water, in certain conditions, it appears to be equally durable. The general condition for the production of such decompositions is contact with a body already undergoing a similar cha7ige. When fresh wood is placed in contact with decaying Avood, or other decaying vegetable matter, the latter acts the part of a ferment, and causes the transformation of the elements of the fresh wood, from the same cause as yest causes a transformation of the elements of sugar. The result differs according to the composition of the sub- stance to be decomposed, and the presence or absence of free oxygen ; but the cause is the same, and the decay in the case of dry-rot may be considered as a process of fermentation and oxidation combined. In this respect it closely resembles acetification or the process of fermenta- tion and oxidation, by which alcohol is converted into acetic acid. By absorb- ing oxygen the alcohol becomes entirely converted into water and acetic acid. But pure alcohol, whether strong or diluted Aviih water, may be exposed to free oxygen without the formation of the smallest particle of acetic acid, or al- teration of any kind ; as also may pure woody fibre without formation of hu- mus. One of the conditions necessary to the conversion of alcohol into acetic acid is contact with a nitrogenized body, as yest, in a state of slow oxidation or putrefaction ; a condition precisely similar to that under which the decom- position of wood is originated. The' transformation of the elements of alcohol, or woody fibre, is considered by M. Liebig as a reflex action of the transforma- tion of the contiguous decomposing body consistently with the physical law proposed in another application, by Laplace and BerthoUet, that " a molecule set in motion by any power can impart its own motion to another molecule with which it may be in contact." 76 PRESERVATION OF WOOD. The albuminous matter which wood contains distributed over the cellular tissue is intimately connected with the decomposition of the wood. It is a nitrogenized substance, and identical in composition with animal albumen; like which body, it is putrescible in a high degree, and therefore an element of fermentation and putrefaction. It is particularly adapted for food for insects, which are often found in the interior of the cells, penetrating the wood in all directions. The disintegration of the fibres, thus occasioned by insects, also greatly accelerates the chemical action going on at the same time, from the increased facility for the introduction of air and water to the mterior of the wood. The products of the spontaneous decomposition of vegetable albumen are the same as those produced from animal albumen ; namely, carbonate of ammonia, nitrate of ammonia, carburetted hydrogen, and water. The influ- ence of ammoniacal salts in favoring the growth of fungi accounts for the ap- pearance of the latter among the earliest signs of decay of wood.* The spontaneous decomposition of the vegetable albumen, acting as a fer- ment, is the primary cause of the decomposition of the wood ; and the pres- ence of sugar, starch, and other matters capable of being easily transformed by a ferment, considerably hastens the decomposition. Hence it is found that those woods which contain the smallest quantity of albumen and amylaceous matters are the most durable. The wood of a tree of the acacia tribe, which has been largely employed of late in France and America for purposes in which the wood is subject to more than ordinary exposure, contains merely a trace of albumen, and hence resists decomposition in situations where all oth- er woods enter into a state of decay. Placed in the same circumstances in which oak-wood decays in one or two years, the wood of the acacia is said to remain perfect for fifteen or twenty years (M. Payenf). Before a considerable quantity of wood is appropriated to building purposes, an experiment should be performed to ascertain, by chemical analysis, the proportion of albumen which it contains. A method recommended by M. Payen consists in digesting the wood with the aid of heat in a dilute solution of caustic soda, which has little or no action on the woody fibre, but dissolves the albumen ; and the quantity of the latter thus separated may be estimated by washing, drying, and weighing the wood. As the presence of starch and gum in the wood would prevent such a pro- cess as the preceding from affording anything more than an approximation ta the proportion of albumen, a more advantageous method would be to deter- mme the absolute amount of nitrogen in the wood by the simple and easy process devised by MM. Will and Varrentrapp for the ultimate analysis of or- ganic bodies. From the proportion of nitrogen thus obtained, that of the al- bumen in the wood may be calculated ; but such a calculation is unnecessary, as the relative amount of nitrogen in different specimens of wood would of course indicate (according to the principles before developed), their relative disposition to decay. An account of the manner of conducting the process referred to, may be found in the " Elements of Chemical Analysis," page 267. § III. PRESERVATIVE MATERIALS. ff the decay of wood is, in the first place, an induced effect of the contact of decomposing albumen, a means of preserving the wood is naturally sug- gested in the removal of the albumen ; or els^ in so modifying it, by causing it to combine with other substances, that it shall no longer possess the prop- erty of decomposing spontaneously. The solubility of albumen in cold and tepid water aff'ords a simple means of withdrawing from the wood this element of decomposition. Unless the wood is in very thin pieces, however, the removal of the albumen by the pro- cess of washing in water is extremely slow. To test the efficacy of merely washing in water, equal weights of washed and unwashed wood, equally dry, » The growth of mushrooms is found to be remarkably acceJorated by watering them with a solu tion of sulphate of ammonia. t Cours de Chimie Ort;anique, 1843. PRESERVATIVE MATERIALS. 77 were moistened with. the same quantity water, and the amount evaporated was replaced in each quantity equally. .In the coarse of a few weeks the un- washed wood was always found to be covered with a thick mould, while none appeared on the washed wood for six months. At the expiration of that pe- riod the unwashed wood was found to have sensibly dmiinished in weight, while the weight of the washed wood remained unaltered (Dr. Boucherie). As the decay of wood advances, the proportion of soluble matter decreases from tive or six to less than one per cent. But, as the removal of the albumen seems to diminish the adhesion of the fibres and the tenacity of the wood, a better method of preserving wood is to cause the albumen to enter into combination with another substance, to form a compound Avhich is insoluble in water, and not susceptible of spontaneous decomposition. This is the mode of action of all the antiseptic substances which have been of late applied to wood, either in aqueous solution or in the form of vapor, as effectual preventives of decay. Corrosive sublimate, or chloride of mercury, is one of the most efficient of these antiseptic applications. It was proposed by Mr. Kyan* as a preventive of dry-rot, under the idea of its acting as a poison to tlie fungi and insects which were the supposed cause of the disease. But this explanation of the action of corrosive sublimate is no longer tenable, as it is now generally ad- mitted that the fungi and insects are not to be considered the origin, but the result of dry-rot. It has been suggested that its action depends on the for- mation of a compound of lignin, or pure woody fibre, with corrosive subli- mate,which resists decomposition in circumstances where pure lignin is liable to decay ; but pure lignin possesses no tendency to combine with corrosive subli- mate. The action of this substance is in reality confined to the albumen, with which it unites to form an insoluble compound not susceptible of spon- taneous decomposition, and, therefore incapable of exciting fermentation.! Vegetable and animal matters, the most prone to decomposition, are com- pletely deprived of their property of putrefying or fermenting by the contact of corrosive sublimate. It is on this account advantageously employed as a means of preserving animal and vegetable specimens. Its expensiveness in this country is a great obstacle to its extensive employment, but few antisep- tic applications are more effectual. In Mr. Kyan's process the wood to be im- pregnated is sawed up into blocks or planks, and soaked for seven or eight days in a solution containing one pound of corrosive sublimate to five gallons of water. The impregnation is sometimes effected in an open tank, and sometimes in an air-tight vessel from which the air is first exhausted by a pump as far as possible ; and the solution is then pressed into the pores of the wood under a force of about a hundred pounds to the square inch. To test the efficacy of Mr. Kyan's process, protected and unprotected piwes of timber were placed in a trench in the Royal Arsenal at Woolwich in con- tact with putrefying vegetable matter, and with pieces of wood affected with dry-rot ; and the trench was covered with horse-dung to increase the temper- ature and accelerate the decomposition. At the expiration of five years the protected wood was found to be unaltered, while the same kind of wood, un- protected, became considerably affected before the end of the first year. *Tlie use of corrosive sublimate was previously siigg-ested to the Admiralty and Navy Bowd by Sir H. Davy ; but, this substance being slightly volatile at common temperatures, it was considered that the atmosphere surrounding the prepared timbers might become vitiated, and the proposal was not at that time carried into execution. t A compound quite similar to, if not identical with, that referred to in the text, is thrown down as a white precipitate when an aqueous sulution of corrosive sublimate is mixed with a solution of white nf es for the application of the process to the preservation of wood for the Frsnch navy. 84 PRESERVATION OF WOOD. DifTerent kinds of liquids are not absorbed with equal facility ; neutral so- lutions, for example, are absorbed more readily than either acid or alkaline. A plantain, the trunk of which was about twelve inches ia diameter, absorbed in seven days two and a half hectolitres (very nearly 8-8 cubic feet) of a solu- tion of chloride of calcium of specific gravity 1-1095 (about 22" Twaddell). An objection to the process of impregnating trees by vital absorption is, that it can only be executed in the sap-season, which is limited to a few months in the year, and the cutting of the wood at this period is contrary to established practice. A simpler and equally effective method, by which trees may be impregnated at all seasons of the year, has since been discovered by Dr. Boucherie, and also, independently, by Mr. W. H. Hyett, of Stroud, Gloucestershire, whose Prize Essay on the best solutions for impregnating trees to impart durability, incombustibility, &c., in the Transactions of the Highland Society,* contains a great deal of highly valuable information. The process consists simply in inverting the newly-felled tree, stripped of all superfluous branches, 'divided into convenient lengths, and if necessary, squared, and applying the preserving liquid to the butt-end of the tree, now the uppermost. The liquid may be contained either in a bag of impermeable cloth, adapted to the upper ex- tremity, or in a cup hollowed out of the end of the tree. In most cases, the liquid quickly penetrates by the superior extremity, and the sap flows out at bottom almost immediately. The operation is terminated when the liquid which issues from the bottom of the piece is the same as that introduced at top. "With some woods, which contain a considerable quantity of gas m their pores, the flowing does not commence until the gas is expelled. It is remarkable that the most porous woods are not those which are most easily penetrated. The poplar resists more than the yoke-elm and the beech ; and the willow more than the pear-tree, the maple, and the plane. The ash, according to Mr. Hyett, completely resists the percolation of the liquid. I am informed by Mr. Hyett that in the month of May every part of the trunks of large beech-trees, with the exception of three or four years' growth immediately around the pith, admitted the solution perfectly. At the same season, nine or ten inches in diameter of the heart-wood of Scotch fir-trees of about two feet in diameter resisted the liquids effectually. The impregnation of timber which has been already seasoned or cut for some time is best attained by first exhausting all its pores of gas, and then introducing the liquid under a considerable pressure. This method was pat- ented by Mr. John Bethell, in 1838. The vessel in which the impregnation is effected, is an air-tight iron tank, of sufficient strength to withstand an internal pressure of two hundred pounds to the square inch. The circular wrought-iron boilers for high-pressure steain- engines, are well adapted for the purpose. The tank is fitted with an air- tight lid or door, and with a common steam-boiler safety-valve, and is con- nected by one pipe with an exhausting air-pump, and by another pipe with a pressure-pump, for forcing the liquid into the pores of the wood. When the wood is introduced into the tank, it is nearly covered with the preserving liquid, and the tank is exhausted of its air. After a short time, air is read- mitted, and the liquid forced into the exhausted pores of the wood by the pressure-pump. In some cases, the penetration of the liquid requires to be assisted by applying a gentle heat to the outside of the tank ; in others, the liquid enters readily after the exhaustion, without the assistance of pressure. The escape of air from the pores of the wood is expedited by placing the logs of wood in a perpendicular or slanting position, with their top ends above the surface of the liquid. The apparatus used for injecting wood with a solution of chloride of zinc (Sir William Burnett's patent), at the Portsmouth dock-yard, consists of a cylinder of fifty-two feet in length, and six feet in diameter, capable of con- taining about nineteen or twenty loads of timber. It is fitted out with a set * Vol. viii. New series, 1843, p. 635. IMPREGNATION WITH FOREIGN SUBSTANCES. 85 of exhausting-pumps, and a set of pressure-pumps, and has been proved up to 200 pounds to the square inch. When tlie cylinder is loaded, the air is exhausted to 27-5 inches of mercury, and the liquid is introduced by a pipe in connexion with a reservoir. Air is then readmitted and pressure applied, and as the wood absorbs the fluid, the cylinder is again exhausted and the pressure renewed, whereby the fluid is driven into every pore of the wood.* § V. OTHER EEFECTS OF THE IMPREGNATION OF WOOD WITH .FOREIGN SUBSTANCES. Besides protection from decay, whether the wood be kept in a dry or hu- mid stale, the following effects may be produced by impregnation with cer- tain foreign substances : — 1. The increase of the hardness of the wood ; 2. The preservation and increase of the flexibility, elasticity, and strength of the wood ; 3. The reduction of the combustibility of the wood ; 4. The prevention of the expansion and contraction of the wood, and the disjunctions which consequently occur in buildings through variations in the hygrometric condition of the atmosphere ; 5. The application of various persistent colors and odors; and 6. The increase of the density of the wood. 1. From the effects of wood prepared with pyrolignite of iron (page 82) on cutting tools, its hardness has been estimated by workmen at double that of the unprepared wood. Of some specimens of beech impregnated by Mr. Hyett, a carpenter con- sidered that with acetate of copper to be the hardest ; those with common salt, yellow prussiate of potash, sulphate of copper, and corrosive sublimate, to be'next in hardness ; and those with pyrolignite of iron, sulphate of iron, and nitrate of soda, next. Of some specimens of prepared larch, the hardest was that with pyrolignite of iron ; the next in hardness were those with sul- phate of iron and corrosive sublimate ; and the next, those with acetate of copper, sulphate of copper, and prussiate of potash. 2. The flexibility and elasticity of wood may be preserved any length of time, according to Dr. Boucherie, by slightly impregnating the wood with some deliquescent substance, as a dilute solution of chloride of calcium or chloride of magnesium, by which a certain degree of humidity is always pre- served in the wood, if exposed to the atmosphere. The solution preferred by Dr. Boucherie, as the most economical, is the mother-liquor of the salt- works, which contains small quantities of each of the above chlorides. The flexibility and elasticity are stated to be in proportion to the quantity of saline matter introduced. A plate of pine-wood charged with the mother-liquor, of three millimetres (-US inch) in thickness, and sixty centimetres (23;6 inches) in length, was capable of being bent into three concentric circles without be- ing broken, and when allowed, would again become straight. Its flexibility and elasticity were found to be undiminished after the lapse of eighteen months. Wood which contains a small quantity of chloride of calcium or chloride of magnesium does not become dry by exposure to the sun in the middle of summer, and the little moisture lost by the wood during the day, is again ab- sorbed at night. The adherance of paints and resinous varnishes does not seem to be affected by the application of these deliquescent substances. The mother-liquor of salt-works would of itself tend to preserve the wood from decay ; for security, however, it is recommended to add to the solution about a fifth part of the pvrolignite. But Mr. Hyett has been led to conclude, from his experiments, that the flexibility of wood does not depend in all cases on the presence of moisture. * United Service Journal, April, 1843. 86 PRESERVATION OF WOOD. Pieces of larch impregnated with acetate of copper and sulphate of copper, were found to be lar more flexible than a piece impregnated with chloride of , calcium. To ascertain the flexibility and strength of wood impregnated with different substances, three specimens of each tree were planed down to an inch square, till they passed as accurately as possible through a gauge, and cut to the length of four feet. The lengths were then placed horizon- tally in a frame so constructed that a Weight suspended from the middle could not vary its position from the irregular bending of the piece ; the ends were supported on props three feet apart. The weights were applied as marked in the following tables every half-minute, and the deflection at the end of the interval, and the breaking point, were noted for each weight. The tables show the mean of the three observations for each piece. I.— DEFLECTION OF BEECH, IN INCHES. Weight applied in pounds. Corrosive subli- mate. — No. 1.* Nitrate of soda. No. 2.* Prussiate pot- ash.— No. 3.* Pyrolignite of iron.— No. 5.* Chloride of sod- ium.— No. 6.* Sulphate of iron. — No. 7.* Sulph'ate of copper.— No. 8.* Acetate of cop- per.— No. 9.* Natural state. No. 17.* Natural state. No. 26.* Natural state. No. 28.* 56 •33 •51 •06 •26 •4 •26 •36 •33 •38 •25 •4 112 •71 1^8 •33 •63 M6 •83 M •86 •84 -.56 •8 140 •98 •5 •85 1-2 1-8 1-26 1-16 •75 1-05 154 1-15 •6 1^0 1-41 2-9 1-55 1^37 •85 1-2 161 1-26 •65 M 1-55 1^76 1^49 •9 1-25 168 1-41 •71 M8 1-73 2-0 1-66 •95 1-35 174 1.51 •76 1-26 1-88 2-21 1-79 1^01 1-4 180 1-66 •81 1-36 2-06 2-48 1^95 1-05 1-5 184 1-78 •83 1-45 2-76 2^1 M 1-55 188 1-86 •88 1^51 3-1 2-27 M3 1-6 192 1-98 •91 1-6 3-6 2-48 M6 1-65 196 2-1 •96 1-66 3-98 2-69 1-2 1-7 200 2-26 1-00 1-76 1-23 1-75 204 2-41 1-05 1-85 1-28 1-85 208 1^08 1-95 1-33 1-9 212 Ml 2^06 1^36 2-0 216 M5 2^16 1-43 2-0 220 1-2 2^3 1^46 2-1 224 1-26 2^41 1-48 2.15 229 1-31 2^6 1-53 2-25 233 1-4 2-78 1-61 2-35 238 1-5 3-01 1-68 2'5 243 1-6 1-78 2-6 247 1.68 1-85 2-75 252 1^8 1-93 3-0 257 1-96 2-03 3-3 261 2-05 2-13 266 2-21 2-23 270 2-4 274 2-58 279 2-83 283 3-16 288 3-48 * The numbers refej to the table— pages 90, 91. IMPREGNATION WITH FOREIGN SUBSTANCES. 87 II.— DEFLECTION OF LARCH, IN INCHES. Weight ap- plied in pounds. Chloride of cal- cium.— No. 13.* Sulphate of iron.— No. 19.* Sulphate of cop- per.— No. 20.* Corrosive subli- mate.— No. 21.* Acetate of cop- per.— No. 22." Pyrolignite of iron.— No. 23.* Natural state. — No. 24.* 1 Prassiate of pot- ash.— No. 25.* 28 •43 •26 •63 •33 •51 •28 •53 •36 56 •83 •63 • 1-5 •73 1^23 •65 1-38 •88 84 1-36 Ml 3-3 1-6 2-68 Ml 4-6 2-03 98 1-73 1-48 2-06 5-03 1^5 105 2-05 1-8 1-81 112 2^43 2-18 2^65 118 2-85 2-85 124 3^73 3.58 128 4-7 " The numbers refer to the table — pages 90, 91.] From the results of Mr. Hyett's experiments, contained in the preceding tables, it appears that the strength of the wood may be greatly increased or diminished by impregation with foreign substances, and that it is most dimin- ished by those substances which tend most to preserve or increase the flexibili- ty of the wood. In the case of beech, the greatest deflection with a weight of 112 pounds is produced by nitrate of soda, chloride of sodium, and sulphate of copper ; but the pieces impregnated with nitrate of soda and chloride of sodium were the first to break, being unable to support a weight of 140 pounds ; the piece with sulphate of copper broke next, under a weight of 161 pounds. On the other hand, the piece of beech which showed least deflection with a given weight, namely that impregnated with prussiate of potash, was the strongest, and able to support the weight of 288 pounds. It is to be observed that the flexibility and strength of larch and beech are not aS'ected in a similar manner by the same substance, but the experiments on both kinds of wood lead to the conclusion that those prepared pieces which are deflected most by a given weight are those which are broken soonest on, increasing the weight, and the reverse. The preceding tables also lead to the important conclusion that the two diff'erent classes of trees, resinous and non-resinous, require very diff'erent treatment. In the beech, and probably all other non-resinous trees, prussiate of potash and pyrolignite of iron are the only agents which do not impair the strength of the wood in its natural state ; while in the larch, prussiate of potash and sulphate of copper are the only substances which do not increase the strength of the wood. By far the greatest strength is imparted to beech by prussiate of potash ; on larch, the same agent produces no alteration. Sulphate of iron diminishes the strength of beech, but considerably increases that of larch. Sulphate of copper and acetate of copper also diminish the strength of beech, but not that of larch. For beech, the sulphates of iron and copper are not so beneficial as the corresponding acetates; this circumstance may be referred to the corrosive action which sulphuric acid exerts on woody fibre, especially on that of trees which do not contain any resin. Acetic acid exerts no such corrosive in- fluence. Corrosive sublimate produces much the same effect on larch as on beech. The pyrolignite of iron may be considered the best single material to be ap- plied to both kinds of trees, but prussiate of potash is decidedly the best for beech, and chloride of calcium the best for larch. 3. The reduction of the inflammability and combustibility of the wood is not the least important of the effects attainable by impregnation with saline sub- stances, especially common salt, chloride of calcium, and chloride of magnesium. Not only is the inflammability of the wood diminished, but its combustion, 88 PRESERVATION OF WOOD. when fairly commenced, is rendered difficult by. the access of air to the car- bonized wood bemg impeded by the ihin film of fused alkaline or earthy salt. 1 wo huts, one built of prepared wood, and the other of unprepared, were set on fire at the same time by applying equal weights of the same lighted combustible matter. When the hut built of ordinary wood had become redu- ced to ashes, the interior surface of the other had hardly become carbonized (Dr. Boucherie). If perfectly dry, there appears to be little or no difference •between the inflammability of prepared and unprepared wood. 4. The expansions and contractions which wood often experiences through changes in the hygrometric state of the atrhosphere, and the consequent loosening of jomts which thereby occurs, may also be prevented or diminished by impregnation with some deliquescent substance. According to Dr. lioucherie, wood containing a small amount of moisture is not subject to these changes m volume, and they may be entirely prevented by a httle chloride ot calcium or chloride ol magnesium. A few large thin tables made of wood tbus prepared underwent no change in form or size during a twelvemonth, wnue similar tables in the same situation, made of unprepared wood, became exceedmgly warped. The addition of a little pyrolignite of iron to the deli- quescent substance is also recommended, to ensure durability. 5. The colors which are most easily applied to wood by the aspirative pro- cess are those which are produced by double decomposition between two sub- stances in solution, the respective solutions being introduced into the wood consecutively. Thus, to produce a blue teint, the wood may be first impreg- nated with a solution of yellow prussiate of potash, and afterward with a solution of persulphate of iron ; or the same solutions may be applied in the reverse order. The teint in this case is derived from Prussian blue. A black teint may be imparted by introducing successively a solution of sulphurei 01 sodium and a solution of acetate of lead, whereby sulphuret of lead is pro- duced. Wood may also be stained black by introducing an infusion of galls and pyrolignite of iron. A green (Scheele's green) may be applied by means 01 acetate ol copper and arsenious acid ; a reddish brown (prussiate of copper), by sulphate of copper and yellow prussiate of potash ; and a delicate vellow (chrome yellow), by acetate of lead and bichromate of potash. A solution of sulphate of copper to which a slight excess of ammonia has been added, penetrates the wood with facility, and produces an agreeable bluish teint. AS the impregnation is not effected equally through the whole substance 01 the wood, the temting is not uniform, but in veins and waves, which pre- sent an agreeable appearance when the wood is worked up and polished, wifvf ?f ^y^"' solutions do not penetrate the same parts with equal facility. In applying acetate of copper and prussiate of potash to larch, It was observed that the sap-wood was colored most, and the heart- wood least, when the acetate was introduced first. But when the prussiate was first applied, the heart- wood became most deeply colored. With sulphate or acetate of copper first, and prussiate of potash next, beech may be made to appear very much like mahogany. Iodide of lead and iodide of mercury can not be applied to wood Avith advantage as coloring materials. Pyrolignite of iron alone produces in beech a dark gray color, from the ac- tion of the tannin contained in the wood on the oxide of iron ; but in larch and bcotch fir it merely darkens the natural color of the wood. Prussiate of potash alone produces a dingy green color. The teints of most of these color- mg materials especially of the prussiates of iron and copper, are improved bv exposure to light ; and the richest colors are obtained when the process is rapidly executed. (Mr. Hyett.) Vegetable coloring matters do not easily penetrate the wood by the aspira- tive process, probably on account of the affinity of the woody fibre for the coloring principle, whereby the whole of the latter is abstracted from the so- lution by those parts of the wood with which it is brought at first into contact. ° Essential oils and other odoriferous matters may be easily introduced into me wood m a state of solution in weak alcohol ; and the odors thus imparted IMPREGNATION WITH FOREIGN SUBSTANCES. 89 are considered to be as durable as those supplied by nature. Wood may also be impregnated with resinous substances in alcoholic solution, by which it may be rendered impervious to water, and far more inflammable. 6. The increase which wood experiences in density by being impregnated with foreign substances is shown in the following tables drawn up from the experiments of Mr. Hyett : — SPECIFIC GRAVITY OF PREPARED BEECH. No. in Table — Preparation. Specific eravitv pp. 90 and 91. r e j No. 28. Dried two years over stove 681 " 26. Soaked in water two years, and dried in air three years 763 " 2. Nitrate of soda 809 " 7. Sulphate of iron 832 " 17. Natural state (green) 840 " 1. Corrosive sublimate 844 " 5. Pyrolignite of iron 859 " 8. Sulphate of copper 866 " 3. Yellow prussiate of potash 876 " 6. Chloride of sodium 888 " 9. Acetate of copper and vinegar 937 SPECIFIC GRAVITY OF PREPARED LARCH. No. in Table— Preparation. Specific eravity. pp. 90 and 91. . ^ ' No. 24. Natural state (green) 488 « 20. Sulphate of copper 533 " 21. Corrosive sublimate 541 " 25. Yellow prussiate of potash 551 " 22. Acetate of copper and vinegar 552 « 13. Chloride of calcium 560 « 19. Sulphate of iron 595 « 23. Pyrolignite of hon 608 The most important results of Mr. Hyett's experiments on the best mate- rials for impregnating wood are imbodied in the following table. 90 PRESERVATION OF WOOD. RESULTS OF EXPERIMENTS ON By Mb. W. H. Hyett. Experiment. s 6 o C u o O d (S Q • Q 1 1 May 3 24 2 It 22 3 ec 23 4 It oU 5 May 5 19 6 <( 21 7 May 6 19 8 July 13 17 9 (C 17 10 May 13 20 11 cc 20 1 12 12 13 May 15 17 14 May 14 15 15 (C 14 16 17 June 2 18 (C 19 July 13 17 ;2o cc 17 it 17 22 tt 17 23 ft 17 24 July 30 25 July 13 17 26 tt 27 tt 28 tt Tree. Beech Larch Scotch fir tt Larch Lime Elm White poplar Beech Larch Beech Pear Beech 55 45-5 48i imperfect 56 34 6| 56 42 61 56 54| 6i 56 28i 7 5.6 34| 8| 12 32 5 \ 29 5 12 22 4 12 34 5 12 21 12 18 3 I- m 56 37 9 56 12 34 6 12 351 7 12 35 5 12 29 6 12 29i 6 12 36 7 12 33 7 Material applied. Corros. sublim. Nitrate soda Pruss. potass Imp. gas-tar Pyrolig. iron Common salt Sulphate of iron Sulphate copper Acetate copper and vinegar Gas-tar Corros. sublim. Chlor, of cal. Corros. sublim. Natural state Sulphate of iron 1 18 3L Sulphate copper Corros. sublim. Acetate copper and vinegar 1 pint Pyrolig. iron Natural state Pruss. potass. large old timber, cut five years, soaked in water contain- ing much carbonate of lime for two years, and after- ward dried in an open shed, cut five years and perfectly dried over a stove cut two years and perfectly dried over a stove 1 pint 1 B _1_ 1 8 JL 1 8 Saturated solution o c m o 16J 12 71 14 17 m m 1 1 91 9 91 71 10 12i 2 1 15 7 6 lOf 2 8 13f 11 0 1 0 10 13| 13' "9 IMPREGNATION WITH FOREIGN SUBSTANCES. 91 MATERIALS FOR PRESERVING WOOD. (Trans, of the Highlavd Society.) Timber, its weight and strength ght in pounds to break. deflection be- ig, in inches. Observations on the state of preservation of the prepared woods, after hav- ing remaiined for nine months in a damp cellar surrounded with decaying saw-dusit full of fungi. Specific grav Average wei| required Last average fore breakii 844 809 876 858 888 832 866 240 162 302 247 ZD I 176 198f 158f 3-63 3- 76 4- 3 2-9 3*81 2-9 2- 71 3- 33 ( Very alean and dry, except where the solution had not touched, ( wheire there are fungi. Covered with fungi, not very damp. Tendency to fungi and decay. Fungi, particularly on parts where the tar abounds. Clean and dry. Very wet:, black, a little fungi. Dry and clear, except where the iron did not reach. Tendency to decay. 937 222 5-73 Dry, much fungi. 574 132 7-87 Tendency to fungi and decay. 600 140 3-6 Dry and clean, with little or no fungi. 474 560 474 730 102 I4li ]08| 152 2- 6-33 3-25 6- Light, dry, and clean. Tendency to decay. A little fungi. Much fungi. 434 126f 4-33 Dry and clean. 840 246i 5-35 Decay amd fungi. 828 259f 5-5 Fungi and mouldiness. 595 533 541 140 91 116 5-66 3-46 3-5 Clean where solution had touched, but not elsewhere. Clean, but a little fungi. Dry and clean. 552 608 488 551 763 100| 137i 88f 88f 282 6-5 5-23 5-83 2-23 2-56 Dry, with a little fungi. 5 Clean and dry, except on the parts untoached by the solu- ( tion. Clean and dry. Light and dry, but a little fungi. Wet, tendency to decay and fungi. 732 681 229 257 2- 5 3- 3 Dry and clean. DYEING AND CALICO-PRINTING. DYEING AND CALICO-PRINTING.* 1 1 History of Dyeing arid Calico-Printing.— II. General Properties of Vegetable Coloring Matters. —III. General Nature of Dyeing Processes.— IV. Calico-Printing Processes. In the various operations of dyeing and calico-printing are exhibited some of the most refined and ingenious applications of chemical science. Though many processes in these arts were practised for ages before any just views were entertained of the chernical nature of tinctorial substances, yet dyeing is strictly a chemical art, and it can not be properly understood without some acquaintance with the chemical properties of the acting bodies. The great object of all dyeing operations is the impregnation of a textile fabric with colored substances derived from animals, vegetables, and min- erals, in such a manner as to render them incapable of being removed by washing with water. The modes of effecting this object vary as greatly as the coloring matters differ from each other in their chemical habitudes. Though the chemical reactions which are exhibited in the various dyeing and printing processes are, for the most part, sufficiently intelligible, yet they are sometimes of a highly complex character ; and the theoretical principles of a few valuable processes, discovered accidentally, are even yet but imperfectlv understood. § I. HISTORY OF DYEING AM) CALICO-PRINTING. In the East Indies, in Persia, in Egypt, and in Syria, the art of dyeing has been successfully practised from time immemorial. In the books of the Pen- tateuch frequent mention is made of linen cloths dyed blue, purple, and scar- let, and of rams' skins dyed red ; and the works of the tabernacle, and the vestments of the high-priest, were enjoined to be of purple. The place of antiquity where dyeing was most extensively carried on, as the general business of the inhabitants, was probably Tyre, the opulence of which city seems to have proceeded in a great measure from the sale of its rich and durable purple. This color was prized so highly, that in the time of Augustus a pound of wool dyed with that material cost, at Rome, a sum nearly equal to thirty pounds of our money. The Tyrian purple is now gen- erally believed to have been derived from two different kinds of shell-fish, described by Pliny under the names purpura and buccinum, and was extracted from a particular organ in their throats to the amount of one drop from each fish. It is at first a colorless liquid, but by exposure to air and light becomes successively citron-yellow, green, azure, red, and, in the course of forty-eight hours, a brilliant purple. If the liquid is evaporated to dryness soon after being collected, the residue does not become colored in this manner. The purple is remarkable for its durability ; it resists the action even of caustic alkalies and most acids. Plutarch observes, in his Life of Alexander, that, at the taking of Susa, the Greeks found in the royal treasury of Darius a quan- tity of purple stuffs of the value of five thousand talents, which still retained its beauty, though it had lain there for one hundred and ninety years. The properties of the coloring juices of shell-fish have been investigated by Cole, Gage, Plumier, Duhamel, and Reaumur, who have succeeded in procuring a purple dye, though inferior to what may be obtained by other dye-stuflTs. _ It does not appear that the art of dyeing was much cultivated in ancient * For a considerable portion of the materials from which the present article is compiled, I am in- debted to iVlr. Mercer, of the Oakenshaw print-works, near Blackbiirn, and to Mr. John Graham, of the Mayfield print-works, Manchester. HISTORY OF DYEING AND CALICO-PRINTING. 93 Greece. In Rome it received a little more attention ; but very little is now known of the processes followed by the Roman dyers, such arts being held, by them, in too little estimation to be considered worth describing. The principal ingredients used by the Romans were the following: of vegetable matters — alkanet, archil, broom, madder, nutgalls, woad, and the seeds of pomegranate, and of an Egyptian acacia ; of mineral productions — copperas, blue vitriol, and a native alum mixed Avith copperas. The progress of dyeing, as of all other arts, was completely arrested in Eu- rope, for a considerable time, by the invasion of the northern barbarians in the fifth century. In the East the art still continued to flourish, but it did not revive in Europe until toward the end of the twelfth, or the beginning of the thirteenth century. One of the principal places where dyeing was then prac- tised was Florence, where it is said there were no less than two hundred dye- ing establishments at work in the early part of the fourteenth century. One of the Florentine dyers having ascertained, in the Levant, a method of ex- tracting a coloring matter from the lichens which furnish archil, introduced this material into Florence on his return ; by its sale be acquired an immense fortune, and became one of the principal men of the city. The discovery of America tended greatly to the advancement of the art, as the dyers became supplied thence with several valuable coloring materials previously unknown in the old world ; among which are logwood, quercitron, Brazil-wood, cochineal, and annatto. A great improvement in dyeing also took place about the year 1560, which consisted in the introduction of a salt of tin as an occasional substitute for alum. With cochineal, the salt of tin was found to afford a color far surpassing in brilliancy any of the ancient dyes. The merit of this application is attributed to Cornelius Drebbel, a Dutch chem- ist, whose son-in-law established an extensive dye-house at Bow, near London, about the year 1563. About the middle of the sixteenth century, logwood and indigo began to be employed in Europe as dyes, but not without considerable opposition from the cultivators of the native woad. The use of logwood was prohibited in Eng- land, by Queen Elizabeth, by a very heavy penalty, and all found in the coun- try was ordered to be destroyed. Its use was not permitted in England till the reign of Charles IT. Indigo, one of ihe most valuable and important of dye-stuffs, was also forbidden to be used in England and on the continent, and denounced as " food for the devil." These, and similar prejudices, were gradually surmounted, and in the eigh- teenth century the art of dyeing made very considerable progress. Madder, from which the color known as Turkey or Adrianople red is produced, then began to be properly appreciated ; and quercitron, a fine yellow dye, was brought extensively into notice by Dr. Bancroft. But the chief improvements of the moderns in this art consist in the employment of pure mordants, and in the application of colors derived from mineral compounds, as peroxide of iron, Prussian-blue, chrome-yellow, chrome-orange, manganese-brown, &c. Each of these coloring matters may be obtained as an insoluble precipitate on mixing together two solutions : in the dyeing processes the proper solutions are made to mix and produce the precipitate within the fibre, by impregna- ting it first with one solution, and afterward with the other. As the precipi- tate thus produced is imprisoned within the fibre, it is not reraoveable by mere washing with water. The mode of dyeing Turkey red, which is the most durable vegetable color known, was discovered in India. It was afterward practise^l in other parts of Asia and in Greece ; and, about the middle of last century, dye-works for this color were established near Rouen and in Languedoc by some Greek dyers. In 1765, the French government, convinced of the importance of the process, caused an account of it to be published ; but it was not introduced into Eng- land until the end of last century, when a Turkey-red dye-house was estab- lished in Manchester by M. Borelle, a Frenchman. M. Borelle obtained a grant from government for the disclosure of his process, but the method which was published does not appear to have been very successful. A better 94 DYEING AND CALICO-PRINTING. process was introduced into Glasgow about the same time by another French- man, named Papillon. Previous to this, however, Mr. Wilson, of Ainsworth, near Manchester, had obtained the secret from the Greeks of Smyrna, and published it in two essays, read before the Literary and Philosophical Society of Manchester ; but the process was said to be expensive, tedious, and less applicable to manufactured goods than to cotton in the skein. The greater part of the Turkey-red dyeing executed in Great Britain is still carried on in the Glasgow district. The ancients seem to have attained considerable proficiency in the art of topical dyeing, or of producing colored patterns on cloths. The variegated linen cloths of Sidon are noticed by Homer, who lived nine hundred years be- fore Christ, as very magnificent productions. In India the art of imparting a colored pattern to a cotton fabric has been practised with great success from time immemorial, and it derives its English name of calico-printing from Cal- icut, a town in the province of Malabar, where it was formerly practised on a very considerable scale. According to Herodotus, who wrote more than four hundred years before Christ, the inhabitants of Caucasus adorned their garments with representations of various animals by means of an aqueous in- fusion of the leaves oi a tree ; and the colors thus obtained were said to be ■so fast as to be incapable of being removed by washing, and as durable as the cloth itself The material of which the cloths were made is not stated, but ihey were probably woollen, as that part of Asia was then, as at present, celebrated for the superior quality of its wool. From the following account by Pliny of the nature of the process of topical dyeing practised by the ancient Egyptians, it would appear that this people had attained such proficiency in the art, as could only have been originally ac- quired by extensive practice and close observation. " An extraordinary method of staining cloths is practised in Egypt. They there take white cloths and apply to them, not colors, but certain drugs which have the power of absorbing or drinking in color ; and in the cloths so oper- ated on there is not the smallest appearance of any die or tincture. These cloths are then put in a caldron of some coloring matter, scalding hot, and after having rernained a time are withdrawn, all stained and painted in vari- ous colors. This is indeed a wonderful process, seeing that there is, in the said caldron, only one kind of coloring material ; yet from it the cloth ac- (juires this and that color, and the boiling liquor itself also changes, accord- ing to the quality and nature of the dye-absorbing drugs which were at first laid on the white cloth. And these stains or colors, moreover, are so firmly fixed as to be incapable pf being removed by washing. If the scalding liquor were composed of various tinctures and colors, it would doubtless have con- founded them all in one on the cloth ; but here one liquor gives a variety of colors, according to the drugs previously applied. The colors of the cloths thus prepared are always more firm and durable than if the cloths were not dipped into the boiling caldron." (Pliny, Hist. Nat., lib. xxxv., cap. 11.) In as few words the principle of the common operations of calico-printing could hardly be more accurately described. The pallampoors, or large cotton chintz counterpanes made in the East In- dies from a very early period, have similar dye-absorbing drugs applied to them by the pencil, and certain parts of the cloth are coated with wax to prevent the absorption of color when immersed into the vessel containing the dye. The topical dyeing of cotton goods seems to have been practised for a con- siderable time in Mexico. When Cortez conquered that country, he sent to Charles V. cotton garments with black, red, yellow, green, and blue figures. iThe North American Indians have also been for a long time in possession of a mode of applying patterns in different colors to cloth. The art of calico-printing does not appear to have been much practised in Europe until the close of the seventeeath or the beginning of the eighteenth century, when Augsburg became famous for its printed cottons and linens. From that city the manufacturers of Alsace and Switzerland were long sup- plied with color-mixers, dyers, &c. The first print-ground in England was HISTORY OF DYEING AND CALICO-PRINTING. 95 founded by a Frenchman on the hanks of the Thames near Richmond, and soon afterward a more considerable one was established at Bromley Hall in Essex. Several others were some time afterward founded in Surrey, in order to supply the London shops with chintzes, the importation of which from In- dia had been prohibited by an act of parliament passed in 1700, on account of the excessive clamors of the silk and woollen weavers. Though merely intended as a protection to the English silk and w;oollen manufacturers, this act had the effect of greatly stimulating and increasing the infant art of cali- co-printing ; for the demand for printed calicoes and chintzes could then be gratified only by printing, in this country, white Indian calicoes, the importa- tion of which was still allowed under a duty. An excise duty of threepence per square yard was imposed on the printed calicoes in 1712, which was increased to sixpence in 1714 ; but the importation of calico being still considerable, a new alarm was raised, and a law enacted in 1720, which prohibited the wear- ing of all printed calicoes whatever, whether of foreign or home production. The operations of the printer were then confined to the printing of linens. The oppressive and absurd act of 1720 was repealed in 1730 ; but the cali- coes then permitted to be printed were to have the warp of linen and merely the heft of cotton, and Avere subject to a duty of sixpence per square yard. With such discouragements, the progress made in calico-printing was ex- tremely slow : so lately as the middle of last century it was computed that only fifty thousand pieces of the mixed cloths were printed annually in the whole of Great Britain ; whereas, at the present time, several manufacturers turn out as much as three and four hundred thousand pieces per annum each. The part of the act of 1730, by which the warp was required to be made of linen yarn, was repealed in 1774 ; but the printed calicoes were still subject to a duty of threepence-halfpenny per square yard, the repeal of which in 1831 has been of the utmost advantage both to the manufacturer and the consumer. The wonderful development which calico-printing has received within the last half-century is to be attributed, in a great measure, to the adaptation of numerous ingenious miechanical inventions. The improvement in patterns, and the reduction in the price of cotton prints during this period, are striking illustrations of the advancement which has been made in machinery. The first improvement on the original wooden hand-printing block,* which is quite similar to the block of a wood-engraving, consisted in the substitution, for some styles of work, of copper plates, about three feet square (similar to those employed for printing engravings on paper), on which a much more delicate pattern could be engraved than on wood. The color being laid on the copper plate and the superfluous color removed by a thin steel scraper, the plate was passed with the cloth through a press similar in principle to that of a copper- plate printer. The engraving of the plate was executed either by a common graver or by a punch. The greatest mechanical improvemerst ever effected in this art was the invention of cylinder or roller printing, which is said to have been first made by a calico-printer at Jouy in France, named Oberkampf, in whose hands alone it remained for some time. The invention appears also to have been made independently by a Scotchman of the name of Bell, and was first suc- cessfully applied in the large way about the year 1785, at Mousey near Pres- ton. Cylinder-printing has received its gre atest development in Lancashire ; and the perfection to which the process has been there brought is the chief cause (k the admitted superiority of our calico-printing establishmeiits over those on the Continent, where cylinder-printing is comparatively but little practised. Printing by the cylinder is executed with not only greater accuracy than by the wooden block, but with a saving of time and labor almost incredible. One cylinder machine, attended by one man to regulate the rollers, is capable of printing as many pieces as a hundred men and a hundred girls could with the hand-block during the same time ; or as much work may be executed by a cylinder machine in four minutes as b^ the ordinary method of block-print- * A description of the various modes of printing cloths now practised will be found in another part of the present article. 96 DYEING AND CALICO-PRINTING. ing in six hours. A length of calico equal to one mile has been printed off with four different colors in a single Lour. The successful application of an engraved copper cylinder was followed by that of a wooden roller having the pattern in relief, the mode of printing by which is known as " surface printing." The " union" or " mule machine," which is a combination in one machii e of the engraved copper cylinder with the wooden roller in relief, was inven.ed about 1805 by Mr. James Burton, of Church, near Blackburn, One of the most iniportant of recent improvements in the mechanical de- partment of calico-printing is a very ingenious method of executing block- prmting with several colors by press-work, in an arrangement similar to one of the naodern type-printing machines. (An account of this mode of printing is contained in another section of the present paper.) Another important modern improvement, more particularly adapted to the press-machine, consists in the substitution of stereotype blocks made of a mixed metal, tin, lead, and bismuth, in the place of the wooden block. During the last century the chemical principles of dyeing and calico-printing were investigated by Dufay, Hellot, Bergmann, Macquer, and BerthoUet, and numerous and valuable improvements were suggested by some of their re- searches. The application of chlorine, by BerthoUet, to the bleaching of tis- sues, especially cotton and flax, contributed in no small degree to the advance- ment of these arts ; it is during the present century, however, and from the researches of numerous chemists still living, that they have received the most essential assistance from chemistry. The chief improvements introduced by the moderns consist, as already observed, in the application of colors derived from mineral substanees. Among the earliest introduced of this class of bo- dies, were iron buff and Scheele's green, which were followed by antimony orange (first applied by Mr. Mercer) and Prussian blue. The two chromates of lead (chrome-yellow and chrome-orange) were next introduced by M. Koechlin of Mulhausen, in 1821, and a few years afterward, Mr. Mercer first applied, on the large scale, the peroxide of manganese, known as manganese bronze. § II. GENERAL PROPERTIES OF VEGETABLE COLORING MATTERS. By far the greater number of the coloring matters employed in the art of dyeing are derived from vegetables, but the animal and mineral kindoms also contribute a small number. Coloring principles are abundantly distributed over all the organs of vegetables, but never in a state of purity ; they are al- ways mixed, more or less, with other substances, and their isolation in a pure state often requires very complicated processes. Only a small number, com- paratively, of these substances have as yet been obtained sufficiently pure to have their chemical composition determined. Like almost all other vegeta- ble principles, they are composed either of carbon, hydrogen, and oxygen, or else of the preceding elements togetner with nitrogen, and have received par- ticular designations derived in general from the names of the plants by which they are furnished. The most common tolor of the vegetable kingdom is green, but as the substance which gives rise to this color in leaves and trees is of an unctuous nature, it can not be easily applied to cloth : to obtain a green, the dyer generally has recourse to the admixture of a yellow with a blue coloring matter. It is remarkable that the most vivid and brilliant o^ vegetable colors, namely, those of flowers and other parts of the plant ex- posed to solar light, are so small in quantity, and so fugitive, that they are of all the most difficult to isolate. In the organs which are protected from the light, as the interior of stems, branches and roots, the coloring matters are generally devoid of all brilliancy, but when separated from the accompanying substances, they exhibit considerable lustre, and are by far the most durable. Nearly all the coloring matters of plants which are capable of being isola- ted are yellow, brown, and red ; the only blue substances which have been procured from plants are indigo and litmus, and no black vegetable sub- stance, strictly speaking, has ever been isolated. PROPERTIES OF VEGETABLE COLORING MATTERS. 97 As a particular class of bodies, vegetable coloring matters do not possess many chemical characters in common ; they are associated rather on account of their common application in the arts, than from the possession of similar properties. Most of them are entitled to be ranked among acids, but others are strictly neutral. By far the greater number of them are soluble in water and always m larger proportion in hot than cold water. Those which are insoluble in water generally dissolve in alcohol, ether, and fixed oils. In dry air, vegetable .coloring matters appear to be permanent, but in humid air, and especially under the influence of the solar rays, they gradually lose color, and become converted, by the absorptioti of oxygen from the air into yellowish brown or colorless compounds. The ultimate action of air or'oxy- gen on organic coloring matters in the presence of moisture, is to convert their cai',.«on into carbonic acid, and their hydrogen into water. Solutions of oro-anic cobring matters in water are acted on by oxygen with far greater facilitv^than the dry colors. The color of some of these bodies is changed in a very remarkable manner by the application of acids and alkalies. The blue color of most flowers that of the flowers of the violet, for instance, is rendered red by acids, and oreen by ^kahes. The purple infusion obtained by boiling red cabbage in water is aflected in a similar manner ; acids produce with it a lively red, and alka- lies a full green. If the dried petals of the red rose are digested in spirits of wme, or hot water, they lose their color without aff'ording any, or at most only a trace of color to the liquid. On adding a few drops of sulphuric acid, however, the liquid immediately acquires a fine red color, and, if a slight ex- cess of an alkali is afterward added, it becomes green. The change from red to green may be produced indefinitely. The purple color of litmus is rendered red by an acid, and blue, not green, by an alkali. Some animal and vegetable coloring matters must undoubtedly be regarded as neutral bodies, that is, as possessing neither the characters of an acid nor those of a base ; but most of them, particularly such as are soluble in water, have all the essential characters of a weak acid, being capable of uniting with and neutralizing salifiable bases, as potash, soda, lime, magnesia, alumina, &c. This tendency to combination is not confined, as some have supposed' to soluble coloring matters and insoluble bases ; but the union is more obvious m such cases, as the resulting compound is always insoluble, while soluble bases usually form soluble compounds with soluble coloring matters. For alumina and certain metallic peroxides, especially peroxide of iron and peroxide of tin, some organic coloring matters possess an energetic attraction. The pigments commonly called lakes are insoluble compounds of coloring matters with alumina or oxide of tin, which may be formed by mixino- a so- lution of alum or of perchloride of tin* with the infusion of the dye-stu%; and adding afterward an alkaline carbonate to liberate peroxide of tin or alumina : as the latter precipitates, it unites with and carries down the coloring matter m solution, frequently leaving the supernatant liquid entirely colorless. The infusion of the dyc-stiiif is sometimes made with an alkaline"liquor and mixed with a solution of alum after being filtered. In this way ijellow lake is made with a decoction of turmeric, and annatto and quercitron lakes from the re- spective dye-stuffs. Important applications are made in dyeing and calico-printing of the attrac- tion which exists between alumina and metallic peroxides on~the one hand, and organic coloring principles on the other. By first impregnating a piece of cloth with alumina, green oxide of chromium, peroxide of iron, or peroxide of tin, and then dipping it into the infusion of the dve-stuff", the coloring mat- ter leaves the solution to unite with the base, forming an insoluble compound, whereby it becomes strongly attached to the tissue, and is rendered less sus- ceptible of alteration by the air, the solar rays, and other decomposing agents. The attractive force of coloring matters for insoluble bases has been regard- ed by some as a naere attraction of surface, analogous to, if not identical with, the force of cohesion or adhesion, being the same as the attractive power by * Commonly called spirits of tin. 98 DYEING AND CALICO-PRINTING. which charcoal is enabled to withdraw coloring^ substances from their solu- tions, and also the same as that by which a solid body condenses a permanent gas upon its surface. This mechanical attraction, which always exerts itself between a solid on the one hand, and a substance in solution or a gas on the other, depends entirely on the state of the surface of the solid, and is in no way connected with the chemical relations of the combining substances. But the combinations of alumina, &c., with soluble coloring matters seem to be cases of true chemical combinations, taking place in definite propor- tions, and under the influence of different degrees of attractive force for differ- ent coloring principles. Thus, alumina has a stronger attraction for the col- oring principle of madder than for that of logwood, and a stronger attraction for that of logwood than for that of quercitron. When a piece of cloth im- pregnated with alumina is immersed in a decoction of quercitron bark, it ac- quires a fast yellow color ; if the same cloth is washed for some time and kept in a hot decoction of logwood, the alumina parts with the coloring prin- ciple of quercitron to combine with that of logwood, and the color of the cloth becomes changed from yellow to purple. If the same cloth is nest immersed for a fiew hours in a hot infusion of madder, the alumina parts with the col- oring principle of logwood to unite with that of madder, the color of the cloth changing from purple to red. The quantity of alumina on the cloth does not appear to diminish while these substitutions are taking place. These inter- esting facts were communicated to me by Mr. John Thom, of the Mayfield print-works. By contact with chlorine, and in presence of a little moisture, the color of most, but not all, vegetable and animal dye-stuffs, is instantly destroyed ; the organic substance is decomposed, being commonly converted into colorless products, from which the original color can not be reproduced by any known process. In at least one case, however, which is that of indigo, the color is reproducible after having been discharged by chlorine, provided the quantity of chlorine applied to the indigo has been no more than sufficient to change the blue color to a buff, and not enough to destroy all color. The rich crim- son color into which some preparations of indigo are changed by chlorine is also convertible into blue, though not to so deep a shade as the original indigo (Mr. Mercer). In most cases of the destruction of vegetable colors by chlorine, the decom- position is effected, without doubt, through the powerful affinity of chlorine for hydrogen, which may be manifested in two ways ; 1st, in the direct abstraction of hydrogen from the organic substance, and 2dly, in the decom- position of water, the hydrogen of which unites with the chlorine to form hydrochloric acid, while the oxygen of the water decomposes the coloring matter, forming carbonic acid with its carbon, und water with its hydrogen. Chlorine does not bleech readily in the absence of a\l moisture, and hydrochloric and carbonic acids may generally be discovered among the products. In a few cases, however, the bleaching action of chlorine simply consists in the dtrect combination of the chlorine v/ith the coloring matter to form a compound which is devoid of color. Chromic acid is another powerful bleaching agent, which acts by affording oxygen to the coloring matter, becoming itself reduced to the state of green oxide of chromium. The color of the vegetable substance is even more readily destroyed than if chlorine had been apphed. Most vegetable coloring matters are also bleached by sulphurous acid in the presence of water. The action of this substance is not so energetic as that of chlorine, and differs from it essentially in the circumstance that the colors are not entirely destroyed, but may in general be restored by exposure to the air, or by the application of a stronger acid or an alkali. It is uncertain whether the bleaching power of sulphurous acid depends on the partial deoxidation of the coloring matter, or lon the union of the sulphurous acid with the coloring matter to form a colorless combination. Charcoal has also been classed among bleachiing agents, as it readily with- draws coloring matters from their solutions, freqiaently leaving the supernatant PROPERTIES OF VEGETABLE COLORING MATTERS. 99 liquid entirely colorless. The charcoal which absorbs coloring matters with most avidity is that obtained by the calcination of bones and other animal matters, the superiority of which seems to depend merely on its minute state of division, whereby the contact of the liquid and charcoal is rendered more perfect. The action of charcoal in bleaching vegetable infusions is altogether different from that of chlorine, and also from that of sulphurous acid. The coloring matter is not decomposed, but is merely mechanically attached to the surface of the charcoal, without having experienced any chemical altera- tion whatever. When brought into contact with deoxidizing agents, several organic coloring matters part with a portion of their oxygen, and at the same time lose their color. But if afterward exposed to the air, or any source of free oxygen, the deoxidized bodies reassume oxygen, and with that element their original color. The colored bodies would therefore appear to be compounds of oxygen with a colorless radical. The alternate reduction and oxidation may be prac- tised on the same substance indefinitely. As examples of coloring matters susceptible of .these changes, may be meniioned litmus, logwood. Brazil-wood, sapanwood, peachwood, red beet-root, and the red cabbage. The most con- venient deoxidizing agents to be employed in such experiments are the fol- lowing : — 1". A mixture of granulated or feathered tin and a caustic alkali. 20. Protoxide of iron, or protoxide of tin, recently precipitated, and still moist. 3 >. Hydrogen gas, applied in the nascent state, by introducing a piece of zinc or iron into the infusion of the coloring matter, rendered acid by the addi- tion of muriatic or sulphuric acid. 4". Sulphuretted hydrogen gas, a stream of which may be passed through the colored infusion, or the latter may be agitated in a jar containing the gas. As the color disappears, a whitish precipitate of sulphur is produced. 5". Double metallic sulphur salts containing an alkaline sulphuret, such as the sulphuret of arsenic and potassium (sulpharsenite of potash). It is worthy of note that the colorless or white radicals of Brazil-wood, log- wood, sapanwood, &c., do not unite with alumina and metallic peroxides to form insoluble compounds or lakes, like their oxides, or the true coloring matters. Other vegetable coloring principles than those above mentioned become converted into colorless substances when exposed to the action of deoxidizing agents, but the chemical change which some of them suffer appears to be the acquisition of hydrogen instead of the yielding up of oxygen. When exposed to the air or other source of free oxygen, this hydrogen is removed, and the original color returns. Indigo is one of the coloring matters susceptible of such changes. Several coloring principles are contained in the plants from which they are derived in their white, deoxidized, or hydruretted state. Such is the case, for example, with indigo. That substance does not exist in the blue or dehydru- retted state in the plant by which it is furnished, but as white indigo, or indi- gotin, the colorless hydruret of indigo-blue. Most vegetable juices, the recent pulp of fruits, detached leaves, &c., become colored brown and yellow by ex- posure to the air, from the absorption of oxygen. If carefully kept in a vessel of some gas devoid of free oxygen, such bodies experience no change in color. Coloring matters have the property of uniting with animal and vegetable tissues, by virtue of an attraction of surface quite similar to that by which they unite to animal charcoal. When well-scoured wool or silk is digested in a decoction of cochineal, logwood, or Brazil-wood, or a solution of sulphate of indigo, it abstracts the color so completely as to leave the liquid colorless, as if animal charcoal had been introduced. The affinity of vegetable tissues for coloring matters is in general not so great as that of animal tissues for the same substances. The vegetable fibre readily combines with a coloring mate- rial ; but unless the latter is insoluble in water, the combination is exceedingly feeble. A familiar example of the affinity of the vegetable fibre for organic 100 DYEING AND CALICO-PRINTING. coloring matters is presented in the staining of a linen napkin by red wine. The portion of the cloth on which the wine falls soon abstracts the whole color from the liquid, becoming dyed red ; but beyond the spot thus produced, the cloth becomes moist without acquiring an appreciable color, the wine having been deprived of all its color by the portion of the cloth with which it came first into contact. The attractive force by which this result is obtained must not be considered as peculiarly subsisting between tissues and organic coloring matters, as many mineral substances are withdrawn from their solu- tions by tissues in quite a similar manner. Thus, cotton cloth readily separates lime from lime-water,* and the insoluble sulphate of alumina from an aqueous solution of basic alum. Vegetable and animal coloring principles are divisible into two classes, with reference to their solubility or insolubility in water. Those which are soluble readily attach themselves to tissues, but only with a feeble affinity, as they may be separated by continued washing in water, especially with the assis- tance of heat. Logwood, madder. Brazil-wood, cochineal, and in fact, the greater number of dye-stuffs, belong to this class. To unite them firmly to a tissue, another substance is applied, which possesses the property of forming an insoluble combination with the coloring matter. Those coloring matters which are of themselves insoluble, or but slightly soluble in water, generally form, as might be expected, much faster combinations with tissues. Indigo, annatto, safBower, and such yellow and brown dyes as contain tannin combined with substances of the nature of apotheme, are the principal members of this class. To eflect their solution, some other solvent than pure water must he applied. Thus, indigo is dissolved by bringing it, through the action of a deoxidizing agent, to the state of white indigo or indigotin, which is soluble » in water in the presence of an alkali or some lime. If a piece of cloth is dip- ped into such a solution, the white indigo is absorbed inio the pores of the fibres, and on exposing the cloth to the air, imbibes oxygen, by which it becomes converted into the original insoluble indigo blue. The latter remains firmly attached to the fibre, being imprisomed within the pores, and therefore incapable of being removed by mere washing in water. The coloring matters of annatto and safflower, though very sparingly soluble in water, are easily dissolved by alkaline liquids, from which they may be precipitated on the addition of an acid. A piece of silk might be dyed with either of these colors, by first impregnating it with the alkaline infusion of the dye-stuff, and then passing it through a weak acid : the best method, however, of dyeing both silk and cotton with annatto or saflSower is by wincing the piece in an imper- fectly neutralized alkaline infusion of the dye-stuff, which contains the color- ing matter in a state of feeble suspension, readily precipitated on a solid body presenting a finely-divided surface, such as cloth. The partial neutralization of the alkali in this process is effected by a very weak acid, or an acidulous salt, such as bitartrate of potash (cream of tartar). Such are the principal general properties of organic coloring principles, a knowledge of which is of the highest importance to the practical dyer and calico-printer. But these bodies differ so much from each other in many re- spects, that the best means of extracting them from the organs by which they are produced, and the most effectual manner of applying them to textile fabrics, can only be discovered by the accurate investigation of the chemical and gene- ral properties of each distinct coloring matter separately. *• Nature of Color. — The appearance of color may almost be regarded as an optical delusion, since it does not exist in the object, but in the light which the object reflects. It is well known that a ray of white light from the sun is resolvable into three rays of the primary colors, red, yellow, and blue. As a mixture or combination of these three colored rays, white or colorless light * The separation of lime from lime-water by cotton cloth is exhibited when a drop of a solution of bleach ing powder (which always contains free lime) is allowed to fali on a piece of cotton dyed with indigo. On the spot where the solution first touches the cloth, the color remains unaltered, the lime only having been there intimately absorbed ; but on the ring surrounding this spot, th» color becomes discharged through the action of the chloride of lime. LIST OF VEGETABLE COLORING MATTERS. 101 may be coasidered, the absence of color depending on the exact equilibrium of the th ree. When the colored rays are partially separated by the refractive force of a glass prism, an image or spectrum is obtained, presenting seven different colors, namely, red, oran/e, yellow, green, blue, indigo, and violet. The orange, green, indig'o, and violet teints proceed from the intermixture in various proportions of the three primary rays. Among opaque substances, there are some which completely absorb the three colored rays incident on their surface, and therefore, having no light to reflect to the eye, appear black. Others, on the contrary, reflect all the light, and are consequently white. But others possess the power of decomposing the light, that is, of absorbing the whole or a portion of one of the three primary rays and reflecting the remainder ; or, it may be, of absorbing unequal • proportions of each of the three rays. When such is the case, the body ap- pears to be colored, not from the inherent possession of a color, but because the light which it reflects to the eye is not homogeneous white light. A blue substance, for example, is said to reflect the blue rays only, or in greatest pro- portion, the yellow and red rays being absorbed. If red, it is said to absorb the yellow and blue rays, and reflect the red ; and by the absorption of the rays in unequal proportions, and by the reflection of more or less of the white or undecomposed light, every shade of color may be produced. The same re- marks apply to transparent colored substances ; only, instead of the decom- posed light being reflected to the eye, it is transmitted. According to this manner of viewing the coloring principle, it has been observed that the art of dyeing consists in fixing upon stuffs, by means of molecular attraction, sub- stances which act upon light in a manner different from the stuffs themselves. The production of white by the combination of the three primary colors is practised in one of the finishing operations to which goods are subjected in the process of bleaching. To whatever length the ordinary operations may be continued, some kinds of goods always retain a brownish-yellow hue, which may be removed, and a pure white imparted, by applying a little smalts, in- digo, archil, or a mixture of Prussian -blue and cochineal pink. In such cases the blue, or mixture of blue and pink, supplies the teints necessary to the pro- duction of white with the brownish-yellow color of the goods. But when the dyer attempts to form white by combining red, yellow, and blue, he often ob- tains a dark brown, or black, because the resulting combination does not re- flect as much light as the three colored ingredients separately. The following alphabetical list of coloring matters, with their origin, uses, and principal chemical characters, may prove useful for reference. The his- tory and applications of some of them will be fully discussed in separate arti- cles. I. LIST OF VEGETABLE AND ANIMAL COLORING MATTERS. Alhanet. — The root of the Anchusa tinctoria. Its coloring principle, which is red, is nearly insoluble in water, but soluble in alcohol, ether, oil of turpen- tine, and fixed oils. It is used as a coloring matter for ointments and other unctuous preparations, but not in dyeing. A variety of alkanet was formerly met with in commerce, derived from the roots of the Lawsonia inermis. Annatto. — A hard paste prepared by inspissating the washings from the fermented seeds of the Bixa orellana. Its coloring matter is yellowish-red, nearly insoluble in water, soluble in alcohol and alkaline liquids. It forms an orange-colored compound with alumina, a citron-yellow compound with prot- oxide of tin, and a greenish-yellow compound with protoxide of copper. It IS used to dye silks golden-yellow, by simply digesting the goods in an alkaline solution of annatto, and orange-red by exposing them afterward to the action of a dilute acid. It is also used to dye cotton yellow, with the aluminate of potash as the mordant, and as a coloring matter for cheese. Archil. — ^A violet-colored paste, made from different species of lichens : that 102 DYEING AND CALICO-PRINTING. of the Canaries, which is the most esteemed, is from the lichen rocellus ; and that of Auvergne, from the lichen parellus. Litmus, turnsole, and cudbear, are merely modifications of archil. The coloring principle of these dye-stuffs is soluble in water and alcohol, and its color is changed by the weakest acids from purple or violet to bright red. It is a brilliant color, but {)ossesses little permanence, and is chiefly used to give a violet or purple bloom as a finish to silks and woollen cloths already dyed with other colors. It is rarely used for cotton goods. Barwood. — This is a dull red dye-stuff, the coloring matter of which is only slightly soluble in water, but sufficiently so for dyeing without the application of another solvent, such as an alkaline liquid, in which it dissolves with facihty. It gives red compounds with alumina and peroxide of tin, and is mostly used for dyeing silks and woollen cloth. The coloring matter of camwood is quite similar in its properties to that of barwood, but is somewhat brighter in color. Both barwood and camwood possess much more permanence than peachwood, for which they are now frequently used as substitutes. Brazil-wood. — This and Sapanwood, Fernambouc-wood, Peachwood, and Nicaragua-wood, are derived from certain species of Cesalpina. Their coloring matter, which seems to be identical, is red soluble in water, rendered purple or blue by alkalies, and yellow by acids. It forms a red compound with alumina, a black compound with peroxide of iron, a violet compound with protoxide of tin, and a rose-colored compound with peroxide of tin. It is of itself a fugitive color, being easily bleached by light with exposure to the air ; but its stability is considerably increased by being combined with peroxide of tin or alumina. It is used in dyeing wool, silk, and cotton, with the tin and aluminous mordants. Of these woods peachwood and sapanwood are the most extensively employed at present. Camicood. — (See Earwood.) Catechu, or Terra Japonica. — This is an extract from the heart-wood of the khair-tree of Bombay and Bengal {mimosa catechu), made by evaporating the decoction of the wood nearly to dryness. Its chief constituent is a variety of tannin, differing slightly in its characters from that contained in galls. Catechu is very soluble in water and alcohol, with the exception of a little earthy mat- ter. It gives a rich brown-gray color with nitrate of iron, a fast bronze by being oxidized through the agency of a mixture of sulphate or nitrate of copper and muriate of ammonia, a brownish-yellow with protochloride of tin, and a reddish-brown with acetate of alumina. It is extensively used in calico-print- ing as a topical broAvn, when mixed with nitrate, sulphate, or acetate of cop- per, and sal-ammoniac. Cochineal.-— A. female insect found on the cactus opuniia or nopal, dried. Its coloring principle, termed coccinellin, is naturally of a purplish-red color ; it is soluble in water and weak alcohol ; its color is changed to red by. acids, and to crimson by alkalies. It forms a fine crimson compound with alumina, a violet compound with protoxide of tin, and a scarlet compound with peroxide of tin. Wool and silk are dyed of a fine scarlet by moans of a mixture of decoc- tion of cochineal with cream of tartar and dyers' spirit, which is a mixture of protochloride and perchloride of tin ; and of a crimson, by a decoction of cochineal with alum and perchloride of tin. Cochineal is also used in the preparation of the pigment called carmine. Cudbear. — (See Archil.) French Berries, called also Avignon berries and Persian berries. — The fruit of the rhamnus infectorius. The berries afford a bright yellow liquid when boiled in water, which gives a golden-yellow color with protochloride of tin, a lemon-yellow with peroxide of tin, a rich yellow with alumina, and a drab with a salt of iron. They are much used as a bright yellow topical color when combined with a tin or aluminous mordant. Fustet or Yelloio Fustic. — The wood of the rhus cotinus, the coloring matter of which is yellow. Being a fugitive dye-stuff, it is very little employed at present in dyeing processes. Fustic or Old Fustic. — The wood of the morus tinctoria. Its aqueous decoc- LIST OF MINERAL COLORING MATTERS. 103 tion is orange-colored, and is brightened by cream of tartar, alum and solution of tin. Its principal use is to dye woollen and cotton cloths of a permanent yellow with an aluminous mordant. It is also used to produce a brownish teint with copperas. Indigo. — A blue insoluble pigment procured by the oxidation of a colorless substance (indigotin) contained in the leaves of the indigofera, by subjecting the leaves to a process of fermentation. Indigo blue may be reconverted to indigotin by applying a deoxidizing agent, and then becomes soluble in alkaline liquids, in which form it may be applied to cloth (see page 100). Kerines o-rams.— Dried female insects of the species coccus tlicis, which are found on the leaves of the quercus ilex or prickly oak. The decoction of ker- mes in Avater is red, and is rendered brownish by acids, and violet by alkalies. Kermes was formerly much used as a crimson dye with a mordant of alum, but it is now superseded by cochineal and lac-dye. Lac-dye. — Stick-lac is an exudation produced by the puncture of an insect on the branches of several plants, by which the twig becomes incrusted with a brownish-red resin. This is a complicated mixture, containing a small portion of a red coloring matter quite similar to that of cochineal. Lac-dye is the residue of the evaporation of the aqueous infusion of ground stick-lac. It is employed to dye wool of a brilliant scarlet color with a mordant of dyers' spirit. The solution of the lac for this purpose is effected in very dilute muriatic acid. Litmus.- — (See Archil.) Logwood. — (Campeachy wood.) — The wood of the hocmatoxylon campechi- anum. Though the coloring principle of logwood is red in its natural state, yet it forms blue or violet compounds with almost all metallic oxides. It is soluble in water, affording .a reddish liquid, which is rendered purple by alka- lies, or, if added in excess, brownish-yellow. It is employed in dyeing all kinds of stuffs of a variety of shades between light purple and black with an aluminous mordant, and between lilac and black with the acetate of iron as the mordant. Madder. — Dutch madder is the root of the ruhia tinctorum, and Turkey and French madder that of the rulia pere<^rifia. According to M. Runge, madder contains five distinct coloring principles ; madder red (called also alizarine), madder purple, madder orange, madder yellow, and madder brown. Madder red is soluble in water, but only in small proportion, and therefore can not be employed in a concentrated soluiion. It is very extensively used in the dye- ing and printing of coUon goods for the production of a permanent bright red color with an aluminous mordant; of a lilac, purple, and black, with oxide of iron ; and of a variety of shades of chocolate with a mixture of the iron and aluminous mordants, with or without the addition of sumach. Turkey madder is preferred for producing the Turkey-red dye, pinks, and light lilacs ; and Dutch madder for producing purples, chocolate, and black. A form of madder containing more coloring matter than the natural root is now met with in commerce, under the name of garancine. This article is said to be prepared by digesting powdered madder in cold oil of vitriol, which destroys most of the constituents of the root, but leaves the red coloring matter unaltered. Nicaragua-wood. — (See Brazil-wood.) Peachwood. — ^See Brazil-wood.) Quercitron. — The bark of the quercus nigra-, or yellow oak, which grows in North America. Its coloring principle, which is yellow, is very soluble in water. Quercitron is much used to impart a yellow color to cotton with the intervention of an aluminous mordant, and to produce drabs with an iron mor- dant, and olives with a mixture of the iron and aluminous mordants. It is also much used, when mixed with a small quantity of madder, to produce an orange with a mordant of alumina. Safflower. — The flowers of the carthamus tinctorius. Safflower contains two coloring matters ; a yellow substance soluble in water, which is of no value in dyeing ; and a fine red substance, insoluble in water, but soluble in an alkaline liquid. It is used to dye silk and cotton of a rose color by wincing^ the piece in an imperfectly neutralized alkaline infusion of the dye-stuff. 104 DYEING AND CAL]CO-PRINTmG. Sandal-wood. (Red Sanders wood.) — The wood of the plerocarpus santa- linus. Its coloring matter is red, scarcely soluble in water, but soluble in alka- line lyes. The color may be applied to tissues by dipping them alternately in an alkaline decoction of sandal-wood and in some acidulous liquid. Tt does not stand exposure to light well. Sapanwood. — (See Brazil-wood.) Sumach, Galls, Valonia, and Sawwort. — These and some other astringent vegetable productions are used to impart to cloth a variety of shades from slate color to black, with peroxide of iron as the itordant. These matters can hardly be classed among coloring matters, as their active ingredients, tannic and gallic acids, are white when pure. By unitiag with peroxide of iron, however, these acids form bluish-black compounds, which are the basis of common writing-ink, and may be communicated to cloth by first boiling the piece in a decoction of the astringent material, and afterward digesting it in a solution of copperas. An infusion of logwood is commonly added to the solution of cop- peras. Vegetable astringent principles are also used in some other dyeing processes, in which their action seems to partake of that of a mordant. Turmeric. — The root of the curcuma longa. Its coloring principle, which is orange-yellow, is slightly soluble in water, and readily soluble in an alkaline solution, becoming dark brown. As a dye, it is applied only to silk. Turnsole. — (See Archil.) Weld. — The entire dried plant, reseda hteola. Its decoction in water is yellow. Silk, woollen, and cotton goods may be dyed of a permanent and bright yellow by a decoction of weld with alumina or peroxide of tin as the mordant. With the latter, weld affords to cloth the fastest vegetable yellow color we possess. Woad. — The coloring matter of this plant [isatis tinctoria) seems to be identical with indigo. Woad is commonly employed as a fermentative addition to indigo in the pastel vat. II. LIST OF MINERAL COLORS EMPLOYED IN DYEING. Antimony Orange. — This orange-red substance has been applied to cloth by passing the piece through a solution of the sulphuret of antimony and a little sulphur in a caustic alkali, and afterward exposing it to the air to precipitate the sulphuret, through the absorption of carbonic acid. Arseniate of Chromium. — This is a fine grass-gieen colored compound, which may be imparted to cloth, by the application, first of a solution of chloride of chromium, and afterward of a solution of arseniate of soda. Chrome-Yellow, or Chr ornate of Lead. — The color of this pigment is bright yellow ; it may be communicated to cloth by the consecutive application of solutions of acetate or nitrate of lead and bichromate of potash ; or the oxide of lead may be first fixed on the cloth in an insoluble state, as carbonate, tar- trate, or sulphate. It consists of one equivalent of chromic acid and one equivalent of oxide of lead. Chrome-Orange, or Subchromate of Lead. — This is a dark orange-red pigment, consisting of one equivalent of chromic acid and two equivalents of oxide of lead. To apply it to cotton, the piece is first dyed with chrome-yellow, and is afterward passed through hot milk of lime, by which a portion of the chromic acid of the chrome-yellow is separated. Manganese Brown [Hydrated Peroxide of Manganese). — Cloth is dyed with this substance by being passed, first, through a solution of sulphate or chloride of manganese ; next, through a caustic alkaline solution, to precipitate pro- toxide of manganese ; and lastly through a solution of chloride of lime, to con- vert the protoxide of manganese into peroxide ; or the peroxidation may be effected by mere exposure to air. Orpiment {Sulpharsenious Acid). — This is a bright but alterable yellow, which may be communicated to silk, wool, and cotton, by first passing the goods through a solution of orpiment in ammonia, and afterward suspending GENERAL NATURE OF DYEING PROCESSES. 105 them in a -warm atmosphere to volatilize the ammonia and precipitate the orpiment. This substance is sometimes applied in the form of a solution in a caustic fixed alkali, in which case the precipitation is afterward effected by- passing the cloth through dilute sulphuric acid. Peroxide of Iron {Iron Buff).— This oxide is applied to cloth to produce a yellowish-brown shade of different intensities, by passing the piece through a solution of a salt of the peroxide of iron, and a solution of an alkalme carbonate, in succession. . . Prussiate of Copper.— A. delicate cinnamon color is sometimes communicated to cotton by means of this substance, Avhich is applied by first passing the cloth through a solution of sulphate of copper, then through a dilute alkali to precipitate oxide of copper, and lastly, wincing ia a solution of yellow prussi- ate of potash, containing a little muriatic acid. Prussian Blue.— To apply this pigment, the cloth may be first impregnated with a solution of acetate of iron (iron liquor), and afterward passed through a solution of yellow prussiate of potash, acidified with a little muriatic acid. Scheme's Green {Ar senile of Copper).— T\\\s grass-green colored substance may be applied to cloth by the double decomposition of nitrate of copper and arseaite of potash ; the cloth being passed through solutions of these salts consecutively. A better method is, first to precipitate oxide of copper on the cloth by the action of an alkali, and to wince the piece afterward m a solution of arsenite of potash. § III. GENEliAL NATURE OF DYEING PROCESSES. The processes by which different kinds of textile fabrics are impregnated with the same coloring material are often very dissimilar, and few dyeing processes are applicable in iheir details to goods of cotton, silk, and wool. For this reason, the observations in the present section refer chiefly to cotton fab- rics the treatment of which requires greater assistance from chemistry than the more easily dyed animal tissues. The dyeing of cottons, however, is mostly practised as a part of the process of calico-printing ; but the chemical principles involved in the different operations are precisely the same, wfiether the cloth is merely dyed and finished in that slate, or both prmted and dyed. The object of the ftrst operation to Fig- 30- which cotton goods are subjected, whether intended to be afterward printed or merely dyed, is the re- moval of the fibrous down or nap on the surface of the cloth. This is effected by the process of singeing, which may be performed in two different Avays equally efficacious. The old method consists in drawing the cloth swiftly over a red-hot semi-cylindrical bar of copper, three quarters of an inch in thickness, placed horizontally over the hue of a fireplace, situated immediately at one end of the bar. The disposition • , u of the different parts of a singeing furnace may be understood with the assis- tance of the sectional representation in fig. 30 ; a represents the fireplace, and b the ash-pit ; c is the semi-cylindrical bar of copper, forming the top of the flue ; and d is the strip of cotton, which is rapidly drawn over the ignited bar, and immediately passed round a wet roller, e, to cool from the effect of singe- ing. In the figure, the flue is represented as passing downward to communi- cate with the common draught-chimney. * For detailed accounts of distinct dyeing processes, the reader is referred to other articles treat- ing of individual coloring materials. 106 DYEING AND CALICO-PRINTING. An iron bar of two inches or more in thickness at the top, was formerlv used instead of a copper bar ; but the latter is found to last about ten times as long as the former, and to singe nearly three times as many pieces of cotton with the same consumption of fuel. With a copper bar, about fifteen hundred pieces may be singed by a ton of coals in a well-arranged furnace. The cot- ton is generally passed over the bar three times ; twice on the side which is to be printed, or the "face," and once on that which is to be the "back i5y this operation the color of the calico becomes very similar to nankeen ' ihe other method of singeing consists in passing the cloth rapidly throu<^h a coal-gas flame, for which a patent was obtained by Mr. Hall of Basford riear Nottingham, in the year 1818. The gas issues from numerous perforations through the upper surface of a horizontal tube, and the cloth to be singed is drawn over the flame rapidly by rollers. In the method first patented, the flame is drawn up through the web of cotton or other fabric by a flue leading into a common draught-chimney; but the draught not being always suflScient to draw the flame through immedmiely, an improvement in the apparatus was devised by Mr. Hall, and patented in 1823, which consisted in placino- imme- diately over the gas-flame a horizontal tube, with a slit lengthwise Ihrou^h Its lower surface, which tube is placed in communication with a fan or an ex- hausting apparatus. An arrangement of this kind, so constructed as to allow the passage of two pieces of cloth at the same time over two gas-flames is capable of singeing, when properly managed, fifty pieces per hour. lhat the colors of the tinctorial matters applied to tissues may appear in their purity, it is essential that the cloth be wholly freed from the foreign mat- ters which adhere to its surface, whether imparted in the processes of spinning weaving, &c., or. else naturally adherent to the fibre of the cloth. In cotton goods, this IS accomplished by the process of bleaching by means of chlorine • and in siJk and woollen goods, by the action of sulphurous acid. ihe ordinary operations practised in the process of bleaching by chlorine consist in subjecting the cloth to the successive action, 1", of a dilute alkaline solution ; 2", of a dilute solution of chloride of lime or bleaching powder (com- monly called "chemic" in bleach-works and print-works) ; and 3", of dilute sulptiunc acid. The operation of submitting the cloth to a solution of bleach- powder IS known as " chemicking ;" and to dilute sulphuric acid, as " sourino- •'' 1 he action of sulphuric acid on the cloth impregnated with a solution of bleach- mg power IS to hberate chlorme by combining with the lime to form sulphate. lUe details of this important process will form the subject of another article- lor the present, the following list of the successive operations to which a coU ton labric is subjected in order to prepare it for printing, will suffice for pur- poses of reference : — ^ 1. Washing in cold water , 2. Soaking for eight hours in boiling lime-water ; 3. Washing in cold water ; 4. Souring ; 5. Washiag : 6. Soaking for ten hour hours in a dilute solution of soda-ash ; 7. Washing; • 8. Chemicking ; 9. Souring ; 10. Washing ; 11. Soaking in solution of soda-ash ; 12. Washing ; 13. Chemicking ; 14. Souring ; 15. Washing; 16. Soaking in hot water ; 17. Squeezing and drying. In the process of bleaching mousselin-de-laines by means of sulphurous acid, the goods are usually passed two or three times through a solution of soap and soda, at about the temperature 130' Fahr.,and then exposed for several hours GENERAL NATURE OF DYEING PROCESSES. 107 to the action of sulphurous acid gas, produced from burning sulphur in a close chamber. The latter operation is termed " sulphuring." The goods are next passed through a very weak solution of caustic soda, dried, and usually im- pregnated with a dilute solution of tin, which imparts considerable brilliancy to the colors afterward applied to the goods. For this purpose, de laines (which are formed of cotton and wool) are impregnated with two different solutions of tin consecutively, one intended to afford oxide of tin to the wool, the other to the cotton. The solution first applied is a mixture of per- chloride of tin and muriatic acid, for the wool ; the nther is stannate of potash,* from which oxide of tin is precipitated on the cotton by passing the piece afterward through dilute sulphuric acid. For the finer work, the sulphuring of de laines is usually performed twice. The only operations to which silken cloth is subjected preparatory to being printed, are, 1", boiling in a solution of soap and soda to remove the " gum ;" 2', passing through dilute sulphuric acid; and 3', washing and drying. To impart a permanent dye to a tissue, it is essential that the coloring ma- terial, or the substances from which it is to be produced, should be applied in a state o£ solution, or in a condition to penetrate to the interior of the fibre of the cloth, either at its open extremity, or through the parietes. If a piece of cloth is dipped into common writing-ink, the black color acquired by the cloth may be removed by washing with water, because the taniiate of iron, which is the basis of the ink, instead of being in solution, is in an insoluble state, being merely suspended in the liquid, and therefore unable to enter the interior of the fibre. To apply the tannate of iron in a permanent manner, it is neces- sary to produce it %oilhm the fibre, which is accomplished by first imbuing the cloth with an infusion of galls or other liquid containing tannin, and afterward with a solution of a salt or iron. That the colors in solution in the dye-beck should attach themselves to the stuff in the form of a compound insoluble in their original solvent, is the principle on which the dyeing of fast colors rests ; and the more insoluble the compound in other liquids, so much the faster the color. In nearly all the different processes for dyeing cloths, the color is applied by one of the four following methods: — 1. From two solutions ; the coloring material not existing in either separate- ly, but produced on the mixture of the two. The cloth is first impregnated with one solution, and afterward with the other. 2. From the solution of the coloring material; the cloth being first irapreg- aated with some substance (usually existing on the cloth in the solid state), which has the property of combining with the coloring matter to form an in- soluble compound. 3. From the solution of the coloring material itself, or its basis ; the cloth having previously undergone no essential preparation. 4. By effecting a chemical alteration of the fibre of the cloth, with the for- mation of a colored product. By the first method of dyeing, which is the simplest and most intelligible, all mineral colors, such as chrome-yellow, Prussian-blue, peroxide of iron (iron buff), and manganese-brown, may be applied to textile fabrics. The proper coloring matter in all these cases is insoluble in water, and is thrown down as a precipitate whenever the two solutions proper for its formation are mixed. Thus, whenever an aqueous solution of the salt called bichromate of potash is mixed Avith an aqueous solution of acetate of lead, an insoluble pre- cipitate of chrome-yellow (chroraate of lead) is produced. In like manner. Prussian-blue is precipitated when a solution of yellow prussiate of potash is mixed with a solution of a salt of the peroxide of iron. In the processes of dyeing cloth with these and all other mineral colors, the mixture of the prop- er solutions, and consequent formation of precipitate, is made to take place within the elongated cell or tube which forms the fibre of the cloth ; so that the resulting solid, being imprisoned within the fibre, is rendered incapable of being removed by mechanical means. The fastness of colors applied to * A solution of oxide of tin in caustic polasli. 108 DYEING AND CALICO-PRINTING. cloth in this way is entirely a mechanical effect, and in no way referable to a chemical attraction of the fibre for the coloring matter. A piece of white cotton cloth moistened with either a solution of bichromate ol potash or of acetate of lead, may be easily cleaned from every panicle of the soluble bichromate or acetate by simply washing with water. But if the piece of cloth is first imbued with the solution of the acetate, and afterward with the bichromate (or the order of impregnation may be reversed), the precipitate of chrome-yellow is produced within the fibre, and can never be removed oy washing with water. The chrome-yellow that is washed away m this experiment was merely loosely attached to the exterior of the fibre It may be observed here, that as all the coloring matter which is deposited on the exterior of the fibre is a loss of material, it is advantageous to remove the excess of the solution with which the cloth is first imbued, by draining, squeez- ing, and sometimes by slightly washing the cloth when taken out of the first solution and about to be immersed in the second. So far as the mere operations are concerned, the processes now commonly practised for applying mineral colors to cloth, are rather referable to the second style of dyeing according to the classification here adopted. Instead of pass- ing the cloth through the two solutions consecutively, one of the two materials usually the base of the mineral coloring matter, is first applied in an insoluble state, and the cloth is afterward winced or agitated in a dilute solution of the other, lo apply ferro-prussiate of copper, for example, to cotton in this way the piece is first impregnated with a solution of sulphate of copper. The oxide of copper is, in the next place, fixed in an insoluble state by passin^^ the cloth through a dilute alkaline solution : and the prussiate of copper il formed, lastly, by wincing the cloth in a dilute solution of vellow prussiate of potash containing a little muriatic acid. The economization of the solution last applied is the chief advantage of such a mode of proceeding over the old method of applying the two solutions in succession, without the fixation of a substance derived from the first ; since the production of any superfluous color- ing material is entirely avoided. In the process of dyeing cotton with chrome- yellow, the same depth of color mav be imparted to a piece containing precip- itated oxide or carbonate of lead, from a solution of eight ounces of bichro- mate of potash to a gallon of water, as from a solution of twenty-four ounces of bichromate in a gallon of water, when the cloth contains only the soluble acetate or nitrate. It is to be observed, that although the mere operations in this kind of work are the same as those of the second style to be noticed im- mediately, yet the principles of the two styles are dissimilar, for the coloring material is not contained in the second solution any more than in the first. lo apply to cloth in a permanent manner those coloring substances which are naturally soluble in water, and have not in themselves a strong affinity for tissues (see page 100), of which kind are the greater number of veo-etable and animal tinctorial matters, it is essentially necessary to effect their con- version on the cloth into compounds which are insoluble in water. This is accomplished by first applying to the cloth some substance (most frequently the sub-salt of a metallic oxide^ which has an affinity for the coloring matter whereby it is enabled to withdraw it from the solution and convert it into an insoluble compound. The substance which thus acts as the bond of union between the tissue and the coloring matter, is distinguished as the mordant. Une circumstance in which this style of dyeing differs from the preceding is, that in this, the mordant must be applied to the cloth before the coloring mat- ter, except in some case where both may be applied at the same time^ but with mineral colors, which may be imparted bv the successive application of two solutions. It IS generally a matter of indifference which of the two solu- tions the cloth is first impregnated with. In its common acceptation by the T)ractical dyer the term mordant is as in- defamte as it is inappropriate, since a includes anv kind of substance which can facilitate the application of a dye-stuff to a tissue. Properly speaking, a inordant IS a substance which has an attraction of surface for the tissue, a cliemical affinity for the coloring matter in solution (see page 97), and the GENERAL NATURE OF DYEING PROCESSES. " 109 property of forming an insoluble conipound with the coloring? matter. By- virtue of the combination of these properties, it is enabled to effect in a dura- ble manner the union of the tissue with the coloring substance. But with the practical dyer, the term mordant has a much wider significa- tion ; even the solvent of the dye-stuff, if the latter is insoluble in water, re- ceives that designation ; thus sulphuric acid is sometimes termed a mordant when employed as a solvent for indigo in the preparation of Saxon blue. The name, which was given by some French dyers at a time when litde was known respecting the chemical principles of dyeing, is derived from morJere, to bite ; the mordant being supposed to exert a corrosive action on the fibre which serves to expand the pores and allow the absorption of the color. In most cases of cotton dveing with the intervention of a mordant, the lat- ter must exist on the cloth about to be dyed in a form insoluble in water. But as it is also essential that the mordant should be contained in the interior of the fibre of the cloth, it must be applied at first in a state of solution, for no substance in a solid form can penetrate to the interior of the fibre. The cloth, therefore, must be first impregnated with a liquid, by the decomposition of which the insoluble substance is to be produced. The form in which a mordant exists on a piece of cloth ready to be dyed is usually That of a sub-salt ; that is, a body of a saline constitution (consisting of an acid and a base), in which the proportion of base is in considerable ex- cess. When a piece of cotton, for example, is moistened with a solution of basic alum (soluble subsulphate of alumina) and dried, an insoluble subsul- phate of alumina is produced on the cloth, containing less sulphuric acid than exists in the soluble subsulphate. It is not probable, however, that, when the cloth thus mordanted is immersed in the dye-beck, the insoluble sub-salt com- bines as such with the coloring matter in solution ; the combination, which is doubtless a chemical one, takes place between the coloring matter and the base of the sub-salt. In this case, either all the acid of the sub-salt or else the corresponding soluble neutral salt is liberated and dissolved, the whole or the excess of base remaining on the cloth to fix the coloring material. When a piece of cotton impregnated with subsulphate of alumina, for ex- ample, is put into the madder-beck, the coloring matter of the madder com- bines with either the whole of the alumina in the subsulphate, or else that portion of the alumina only which is in excess over the amount contained m the soluble sulphate. In the first case, the subsulphate of alumina is simply decomposed into alumina on the one hand, and sulphuric acid on the other; while in the second case it is resolved into alumina on one side, and the solu- ble and neutral sulphate on the other, r 1- ■ From the preceding observations may be inferred the necessity of distinguish- in P rtreL^rattaSS^ ^"'^ m^JeHal become: permanently attached. Ihe second mordant wh ch is applied in this mannpr IS known among dyers by the name of alterant, proposed^ Dr Banc "of^ A particular examp e will render such a process m^re intellio-fble If a piece of rnlnr l M tT'^'T ^^g^ood, the cloth assumes an uneven violet color, feebly attached and removeable by washing. But if the perSloride re- maming on the surface is tboroughlv removed before the cloth L nut into X decoction, the piece assumes a dSll brownish violeTLnt • b7p op^edv adiust jng the strength of the solution of perchloride to thS of tL^ dTco Ln atter may be entirely deprived of color. If, in the next place a sSl auan uy of a solution of perchloride of tin, or acetate of alumina is aS to the ''''' - ^^^^^ - ^r of logwood, peroxide of tin forms a compound possesse^of a hvercSoI which compound IS capable of uniting loosely with more of the coS maU e of logwood, the proper teint of which, by itself, is red. The co S ma - ter in excess does not partake of the lively violet or purple teint of 3 mav plv nfl';'™.:dt^7as;?^ T'^'^'f- 4^-^^^ niorLnrbuTthe el^ct of ap^ SthTexceTof colirt r'"'^ ^^"^'^"^'^^ ^ "^^^^^^ compound wi ntne excess ot coloring matter possessing the proper violet or purple color Josed tZS^Jilu'r'"" "i?"'^ '''' rnordan'ied'and washed cKth s cxI posed, is mixed with a very small quantity of a free acid, the precipitation of an excess of coloring matter is prevented partly, it would seerZouTthe solvent power of the acid) ; so that the cloth as umes a Lely ^dor at once and the application of an alterant is unnecessary ^ ' thai ofrm?rrnt'' Wt" -^^f ^f'r "^^^'"^"^^ ^^at its action partake of matte" ^ "'''"'^^^ combination with the coloring In an extended sense, tbe term alterant may be applied to any substance which can effect a permanent change in the color of a dyed cS whatever S m ^'T- "'^^l'^ ^-^i J becomes an alterant when Ip- phed to the purple woollen cloth obtained by cochineal with a rnordant of GENERAL NATURE OF DYEING PROCESSES. Ill nrotoxide of tin, whereby the purple becomes changed to scarlet ; bichromate rpotash may also be called A aherant when applied to a piece of cotton dyed viok with logwood and alumina, in order to change the Yiolet into a black In aTewcales, where the affinity of the J^^^^^XtTom not sufficiently strong for the former to separate, by itsell, the mordant trom ?h suStance^with which it is already in «"™bination the so u„^ mordant and that of the coloring material may be mixed without the tormation precipUate. Thus, no precipitate of coloring matter and mordant ensues when the soluble combination of alumina and caustic potash (alummate of potash) is mixed with a solution of the coloring matter ol annatto ; nor when a solu ion of protochloride of tin is added to a cold decoction of logwood. When his is the case, the cloth is not always first impregnated with the mor- Lt and'fterward with the coloring matter, but both -^Y be applied at once bv exoosin!i^ impurity which common alum is likely to contain of greatest moment to the practical dyer is zron, existing in the state of sulphate fusually both of he peroxide and protoxide), and chloride. It is deriVed froTUe Ser liquor from which the alum was crystallized "'^"'^^^ ^i^om tlie mother- The readiest method of detecting this impurity is by adding to the aaueous solution of alum a few drops of a solution of yellL or^red prussiate of pTaT tTace ofTon '^'^^^'^'V^- precipitate o/prussian blue^ithtverrsmali Ipnfr 11 precipitate at first produced with the yellow prussiate is ffrTaKrinu^T^^^^ becomes blue on exposing fhe r^xS to he air lor a lew mmutes. In this case the iron is present in the alum in the state the sulphuric acid. To prepare Dure ahfrninn H, i ; ^""^l' ^ process, but retains some of in dilute sulphuric acfd, prec p,>rted bv am?.?n ."'"tk '•^dissolved minais very soluble in water and diSif t^^-^ f^v '^ "1"°^" neutral sulphate of alu- beco.es coUon alu'^,^niSl„t^h7JL'LSit aad ^e'rVeas^/cl^s^talLrd^^^ P"'^^^> ^ ALUMINOUS MORDANTS. 113 of a salt of the protoxide ; and a solution of the red prussiate, instead of the yellow, causes the immediate production of Prussian blue. If the solution of alum to be tested is first boiled with a few drops of nitric acid to convert the protoxide of iron into peroxide, Prussian blue is immediately formed on apply- ing the yellow prussiate. In the few processes of cotton-dyeing in which alum is employed as the mordant, the strength of the solution of alum and the manner of applying it entirely depend on the nature of the dye and the depth of the color to be pro- duced. In most cases, where the entire surface is to be impregnated with the coloring material, the goods may be allowed to remain for twenty-four hours, or more, in a cold solution containing about one part of alum to four parts of the cloth, with as much water as is requisite to cover the cloth. Silk may be digested for from eight to twenty-four hours, or longer, in a cold solution of three or four parts of alum to ten or twelve parts of silk and one hundred of water. AVool may be impregnated with alum by heating it in a solution con- taining of alum from one sixth to one fourth of the weight of the wool, and maintained at the boiling point for one hour, or a little longer ; but ebullition for two hours is prejudicial. A very common addition to alum when employed as a mordant, especially for wool which is intended to be brightened by an acid after being dyed, is tartar (crude cream of tartar), which diminishes the tendency of alum to crystallize, and brightens the resulting color. The quan- tity which is added varies for different dye-stuff's from one fourth to one half of the weight of the alum. When employed as a mordant for topical or steam colors, a quantity of sugar is usually added to the alum. 2. iSasic alum. — As common alum, of itself, has very little disposition to form an insoluble subsalt, it is a weak mordant for cotton goods, and has. hence been superseded by other aluminous preparations, from which subsalts may be more easily produced. One of these is basic alum, which is made by separating from common alum a portion of its acid by the application of an alkaline carbonate. It is found that one third of the acid contained in com- mon alum is sufficient to retain in solution all the alumina of the alum, pro- vided the liquid is cold and in a concentrated state. The partial separation of the acid may be eff'ected either by carbonate of potash or carbonate of soda, added until it begins to produce a permanent precipitate. A gelatinous precipitate is formed from the first additioa of the alkaline carbonate, but it redissolves on stirring, until two thirds of the quantity necessary for complete saturation has been applied.* In this state alum is a powerful mordant, as the excess of base is held in solution very feebly, and is easily removed in the state of an insol- uble subsulphate through the surface attraction of the tissue. Animal charcoal also readily withdraws the excess of alumina, by virtue of the same force, A solution of subsulphate of alumina is also produced when chalk is digested in a solution of common alum, sulphate of lime being then formed. Accord- ing to Hausmann, one part of alum, with the addition of one eighth part of chalk, may be retained in solution during summer by five parts of water. One part of common alum requires between eighteen and nineteen parts of cold water for its solution. A solution of basic alum prepared by an alkaline carbonate, as above, can not be well employed except in a concentrated state, as mere dilution with water determines the formation of a precipitate of insoluble subsulphaie of alumina. But this inconvenience maybe overcome, and an excellent mordant obtained, by adding acetic acid to the solution of basic alum. The mixture thus formed, which is quite analogous to common red liquor, aff'ords no pre- cipitate on dilution with water. 3. Red liquor and acetate of alumina. — Red liquor is much more extensively employed as a raoirdant than any other preparation of alumina. The com- mon method of preparing this liquid for the use of the dyer and calico-printer * A convenient mode of preparing the solution of basic alum is to dissolve in water two thirds of the quantity of common alum operated on, to add carbonate of soda to the solution until the mixture exhibits a slight alkaline reaction, and then to add the remaining one third of alum witi» agitation. 8 114 DYEING AND CALICO-PRINTING. IS by adding a solution of acetate of lead or acetate of lime to a solution of alum, when a portion of the sulphuric acid of- the alum combines with the oxide of lead or the lime of the acetate to form an insoluble sulphate, and the acetic acid previously in combination with oxide of lead or lime combines with alumina to form a soluble acetate. To produce complete decomposition both of the sulphate of alumina and the sulphate of potash in the alum, with formation of sulphate of lead and acetates of alumina and potash, 478 parts, or 1 eq. of alum, require 756 parts, or 4 eqs. of crystallized acetate of lead. And for the complete decomposition only of the sulphate of alumina in the alum, 478 parts, or I eq. of alum, require 567 parts, or 3 eqs. of crystallized acetate of lead. The reactions which occur on mixing solutions of these materials in the latter proportions are expressed in the following diagram: / 1 eq. sulphate of potash J \ 24 eqs. water alum \ 1 eq. sulphate ^ I ''I- alumina. 1 eq. acetate / of alumina ) ^ ^1^, sulphuric of alumina. ^ ( acid ^ ^ 3 eqs. C 9 eqs. water acetate < 3 eqs. acetic acid . . of lead ( 3 eqs. oxide of lead But the quantity of acetate of lead employed in the preparation of red liquor IS never greater than that of the alum, and commonly one third less, the pro- portions being slightly varied according to the purposes for which the mordant IS required. A small quantity of carbonate of soda (from one twentieth to one tenth of the weight of the alum) is also sometimes added to the mixture to separate a portion of the sulphuric acid contained in the excess of alum. The following proportions of the materials afford a strong mordant of specific gravity about 20° Twaddell* (1,100), "well adapted for producing dark reds with madder : No. 1. 5 gallons of water, 10 pounds of alum, 1 pound of soda crystals, 10 pounds of acetate of lead. The alum is first dissolved in boiling water, and to this solution the soda is added gradually ; when the effervescence is subsided, the acetate of lead is added in a state of fine powder, and the mixture having been well agitated is allowed to stand for the sulphate of lead to settle, after which the supernatant liquid may be decanted for use, A red liquor, better adapted than the above for producing a yellow dye with the coloring matter of quercitron, may be made by mixing, in the same manner, No. 2. 5 gallons of water, 10 pounds of alum, 1 pound of soda, 7| pounds of acetate of lead. In consequence of the expense of acetate of lead, this salt is commonly superseded, in the preparation of red liquor, by acetate of lime, obtained by * Degrees on Twaddell's Iiydiometer may be converted into the ordinary sp. gr. formula (water heing 1,000) by multiplying them by 5 and adding 1,000. 3 eqs. sulphate of lead. ALUMINOUS MORDANTS. 115 neutralizing with quick-lime the crude acetic acid or pyroligneous acid afforded by the distillation of wood ; but the red liquor thus prepared does not produce with coloring matters such delicate and bright shades as that prepared by acetate of lead. The usual proportions of acetate of lime and alum employed for this purpose are two pounds and a half of the latter to a gallon of solution of the former of specific gravity 12° or 13° Twaddell. As met with in com- merce, red liquor usually has a spec. grav. about 18° Twad. The following mode of preparmg red liquor by acetate of lime is recom- mended by M. Koechlin-Schouch [Bulletin de la Societe induslrielle de Mul- hausen, t. i. p. 277). In twenty-five gallons of hot water dissolve two hundred pounds of alum, and to the solution add three hundred pounds of the crude solution of acetate of lime of specific gravity 16° Twad. The resulting red liquor has the density, while hot, of 22" Twad., but on cooling it deposites crystals of alum, and falls in specific gravity to 18° Twad. In neither of the preceding preparations is sufficient acetate of lead or ace- tate of lime employed to decompose the whole of the sulphate of alumina in the alum, and it is doubtful, moreover, whether acetate of hme, in any quan- tity, would effect the complete decomposition of sulphate of alumina. Eut this undecomposed alum or sulphate of alumina, instead of being useless, as some have supposed, forms a highly important constituent of the mixture. By its action on the acetate of alumina in the solution, it gives rise to the formation of subsulphate of alumina or basic alum, and free acetic acid, and the latter serves to retain the former in a state of more permanent solution than water would alone. On applying heat to red liquor, a precipitate of subsulphate of alumina is produced in the liquid, containing, according to the analysis of M. Koechlin- Schouch, eight equivalents of alumina and three equivalents of sulphuric acid, or, eight times as much alumina as the neutral sulphate in common al- um. The temperature at which the precipitation commences varies accor- ding to the strength of the liquor and the proportions of acetate of lead and alum employed in its preparation. When made as No. 1, page 114, the pre- cipitation commences at about 154° Fahr. If the source of heat is withdrawn soon after the precipitate appears, so as to avoid the evaporation of acetic acid and the aggregation of the precipitate, the latter completely redissolves as the liquid cools; but if the heating is continued until a sensible quantity of the acetic acid is evaporated and the precipitate is become dense, the subsul- phate does not redissolve on cooling, nor even on the addition of free acetic acid. Such a precipitation of insoluble subsulphate, accompanied with the evaporation of acetic acid, always occurs during the drying and " ageing" of cottons printed with red liquor.* A solution of pure acetate of alumina obtained by dissolving recently-pre- cipitated hydrate of alumina in acetic acid is uncrystallizable, and driesj on evaporation, into a gummy mass, very soluble in water. The aqueous solu- tion of the pure acetate may be boiled without decomposition ; but if a solu- tion of alum is added to acetate of alumina, so as to form a mixture analogous to red liquor, the liquid affords, on the application of heat, a precipitate of subsulphate, of the same composition as that produced from common red liquor, which redissolves on the cooling of the liquid if the acetic acid has not been expelled. Acetate of alumina made without excess of alum is very rarely used as a mordant, the proportions of alum and acetate of lead employed in almost all cases being four parts of the former to three parts of the latter. The chief use of the pure acetate, or rather of the mixture of pure acetate with sul- phate of potash, such as is obtained by mixing eight parts of alum with nine and a half parts of acetate of lead, is to add to mixtures for topical colors containing a strong acid, such as muriatic, sulphuric, or nitric, in the free state. The strong acid combines with the alumina of the acetate, and liber- ates acetic acid, which exerts no corrosive action on the fibre of the cloth. * Concentrated red liquor deposites a small quantity of the subsulphate of alunnina at com- mon temperatures, if kept for a considerable time. The precipitate thus gradually formed is some- times too aggregated to be redissolved on the apphcation of acetic acid. 116 DYEING AND CALICO-PRINTING. 4. Aluminate of Potash. — Another preparation of alumina much employed as a mordant for cotton goods, is the solution of alumina in caustic potash, known as the aluminate of potash. The following method of preparing this solution is recommended by M. Kcechlin-Schouch. A solution of caustic pot- ash is first made by boiling for half an hour a mixture of eighty pounds of carbonate of potash, thirty-two pounds of quick-lime, and forty gallons of wa- ter. The caustic ley being allowed to settle, thirty gallons are decanted and evaporated down to the density 35° Baume (60° Twaddell), and sixty pounds of powdered alum are added to the boiling liquid. As the solution cools, a quantity of sulphate of potash is deposited in crystals. When a piece of cloth impregnated with the aluminate of potash is sus- pended freely in the air, the carbonic acid of the atmosphere seizes upon the caustic potash which holds the alumina in solution, causing the formation of carbonate of potash and precipitation of alumina. If the apartment in which cottons printed with the aluminate of potash are suspended is imperfectly ven- tilated, after a short time not a trace of carbonic acid can be detected in the atmosphere by the ordinary test of lime-water ; hence the necessity of pay- ing particular attention to the means of producing a proper ventilation in the " hanging" or " ageing" room, if the complete precipitation of the alumina during that stage of the process is required. The time of hanging the mordanted goods, however, is seldom prolonged sufficiently to allow of the complete decomposition of the aluminate of pot- ash. This is insured by afterward passing the cloth through a dilute solution of muriate of ammonia,* which immediately determines the complete pre- cipitation of the alumina. The reactions which take place when a solution of aluminate of potash is mixed with a solution of muriate of ammonia are expressed in the following diagram : — . , • , ( Alumina ----- free. Aluminate > . r\ ^ , V < „ s Oxygen.... ■ — water. of potash ^ Potash J Pou'ssium ^ Muriate of J ^uj-. j Hydrogen ^ n r t ^nm ammonia ) ^ ^ Chlorine chloride of potassium* Ammonia ----- free. The aluminate of soda may be prepared in the same manner and used for the same purposes as aluminate of potash. It is said that no difference is perceptible between the eflects obtained by aluminate of potash, and those by aluminate of soda. The other simple preparations of alumina which are occasionally used as mordants are, nitrate of alumina, chloride of aluminum, and tartrate of alu- mina. Of these, the most extensively employed is the nitrate, which may be prepared of sufficient purity for the use of the dyer and calico-printer by mix- ing concentrated solutions of equal weights of alum and nitrate of lead, when sulphate of lead is formed and precipitated, and nitrate of alumina remains in solution. Tin mordants. — Several preparations of tin are employed as mordants in dyeing and calico-printing, comprising salts of the protoxide and of the per- oxide, and mixtures of the salts of both oxides. The oxides of tin have a strong tendency to unite with soluble vegetable and animal coloring matters, producing distinct and definite combinations; and the compounds with the peroxide are generally distinguished for possessing a vivacity of teint far su- perior to that presented by the combinations of the same coloring matter with any other mordant. Peroxide of tin is used as a mordant chiefly with cochineal. Brazil-wood, peachwood, barwood, French berries, and logwood, and is commonly applied . * The muriate of ammonia is sometimes mixed with the duns-beck, and sometimes with the so lution of "'dung substitute. " In a few particular styles of caiit-o-printing. where the ageing of cottons printed with aluminate of potasli is altogether omitted, the clotli is passed through a solu tion of muriate of ammonia before the dung emulsion. TIN MORDANTS. 117 in the state of a solution of the perchloride (permuriate), or as a mixture of the solution of the perchloride with that of the pernitrate. Such solutions, which are known among dyers by the name of red spirits or simply spirits, may be obtained by dissolving metallic tin, in a granulated or " feathered" state, in one of the following liquids : 1°. Aqua regia, which is a mixture of nitric and muriatic acids; 2°. A mixture of nitric acid and muriate of ammonia ; and 3°. A mixture of nitric acid, muriate of ammonia, and common salt. The perchloride of dn, or a mixture of the perchloride and pernitrate, is aiso sometimes prepared from crystals of the protochloride (salts of tin) by means of nitric acid or aqua regia. The nitric acid used for this purpose should be quite free from sulphuric acid. A great number of receipts for the preparation of this mordant have been prescribed, varying very considerably in the proportions of the materials, ac- cording to the nature of the fabric to be dyed, and that of the dye-stuff for which it.is to be used as the mordant. Some of the preparations contain the peroxide or perchloride only ; but others, which are preferred for general use, contain both the perchloride and the protochloride. A common process for preparing a mixture of the two chlorides is to add granulated tin very grad- ually to a mixture of three parts by measure of muriatic acid, and one part of commercial nitric acid, so long as any tin is dissolved in the cold. If the tin is not added gradually, instead of being dissolved, it is converted into the in- soluble peroxide, which is deposited as a white powder. The above proportions answer well for a mordant for general use, and es- pecially for Brazil-wood ; but for particular purposes the proportions of mu- riatic and nitric acids are varied from six parts of the former, and one of the latter, to equal parts. The solution of the perchloride of tin, or mixed perchloride and protochlo- ride made by dissolving tin in a mixture of nitric acid and sal-ammoniac, is much used by silk and woollen dyers, but a considerable difierence exists be- tween the proportions of the materials as recommended by different dyers. For general purposes, the solution afforded by the following proportions re- ceives a decided preference : — 3 quarts of nitric acid of specific gravity 1'300, 4 quarts of water, 12 ounces of muriate of ammonia, 30 ounces of granulated tin. The muriate of ammonia is first dissolved in the mixture of acid and water, and to this solution the tin is added in small quantities at a time, so as to pre- vent the mixture from becoming very hot. The salt met with in commerce under the name of pink salt is the double perchloride of tin and muriate of ammonia (chloride of tin and ammonium), which is made by adding muriate of ammonia to a solution of the perchloride, and evaporating to obtain crystals. It is chiefly used as a mordant with peach- wood. Peroxide of tin is often applied to cloth in the state of the soluble combina- tion of caustic-potash and oxide of tin, known as stannate of potash, which may be obtained by adding a solution of caustic-potash to a solution of per- chloride of tin, until the precipitate at first produced is entirely redissolved. If a piece of cotton impregnated with such a solution is dipped into dilute sul- phuric acid, or a solution of muriate of ammonia, the alkaline combination on the cloth is decomposed, and peroxide of tin percipitated within the fibre. The decomposition which ensues on mixing stannate of potash with muriate of am- monia is quite analogous to that which occurs on the mixture of aluminate of potash with mariate of ammonia (page 116). Protoxide of tin is frequently used as a mordant alone, as well as the per- oxide. This oxide may be applied from the protochloride of tin, which is prepared by dissolving metallic tin in pure muriatic acid to saturation, with the assistance of heat. One part of tin may be dissolved in about three parts 118 DYEING AND CALICO-PRINTING. of concentrated muriatic acid, and on evaporation the solution affords small colorless cry stals, distinguished as salts of tin. The solution of the protochlo- ride is known among dyers by the name of plum spirits, being used in the preparation of the plum tub, which is a mixture of decoction of logwood with the prolochloride. This salt has several interesting applications in calico-printing, both as a mordant and a deoxidizing agent, to which we shall again have occasion to advert. The solution of protoxide of tin in a caustic alkali, obtained by ad- ding the alkali to the solution of prolochloride of tin until the protoxide at first precipitated is redissolved, is frequently used in the place of the protochloride. When exposed to the air, a solution of protochloride of tin absorbs oxygen, and affords, if not very acid, a white precipitate consisting of a subsalt of the peroxide. This inconvenience may be counteracted to a great extent by the addition of muriate of ammonia which combines with the protochloride to form a double salt, less disposed to absorb oxygen than the pure protochloride. The colors of the compounds of coloring rnatters with peroxide of tin are generally much brighter than those of the same compounds with protoxide of tin, but solutions of the protoxide enter the pores of cotton fabrics better than solutions of the peroxide. On this account, a practice sometimes pursued in dyeing cotton goods by a tin mordant, is first to apply the tm in the state of protochloride, and to form the peroxide afterward, within the fibre, by win- cing the goods in a dilute solution of chloride of lime. Iron Mordants. — The principal simple preparations of iron which are em- ployed as mordants are the following: copperas, which is the sulphate of the protoxide ; iron liquor, which is an impure acetate of the protoxide ; the per- nitrate, the sub-persulphate, and the perchloride. The most available of these forms of iron is copperas; but this salt is not well adapted as a mordant for cotton goods, as the powerful aflinity of sulphuric acid for protoxide of iron is an impediment to the formation of an insoluble subsalt. Acetate of Iron ; Iron Liquor. — The iron mordant commonly used in calico- pririting is the acetate, which may be prepared by mixing a solution of acetate of lime, or acetate of lead, with a solution of copperas. A double decomposition occurs on the mixture of these solutions, with the formation of sulphate of lime or sulpha,te of lead, which falls as a heavy precipitate, and acetate of protoxide of iron, which remams in solution. For the complete decomposition of copperas by acetate of lead, 10 parts of the former require about 13^ parts of the lat- ter ; but in the preparation of acetate of iron in this wav on the large scale, the copperas is always employed in excess, being seldom'in so small a propor- tion to the acetate of lead as an equal weight. By exposure to the air the acetate of the protoxide becomes partially peroxidized, being converted into a subacetate of the peroxide. But nearly all the acetate of iron used in print-works is now prepared by digesting, for several weeks, old iron hoops, nails, &c., in the crude acetic acid obtamed by the distillation of wood. A dark brown solution, known as the pyrolignite of iron or iron liquor, is thus obtained, composed of the ace-' tate of the protoxide of iron, and a quantity of tarry, oily, and spirituous mat- ters, produced in the destructive distillation of wood. As a mordant, this mixture is in general preferred to the purer article prepared by means of acetate of lead or acetate of lime, probably because the peroxidation of the protoxide of iron by exposure to the air during the "ageing" of the goods is retarded by the spirituous and unctuous matters present, which have a stronger affinity for the oxygen of the air. A small quantity of the acetate of the peroxide of iron is sometimes contained in iron liquor, but by no means as an essential constituent. The principal pure persalt of iron used in dyeing and calico-printing is the nitrate, which is prepared by dissolving clean pieces of iron in nitric acid of specific gravity 1-305. Soon after the evolution of brown fumes ceases, the acid solution should be decanted, so as to avoid the formation of the insoluble sub-pernitrate of iron. This solution of iron is used as a mordant with vege- table coloring matters, and also for producing a buff color with an alkali (see page 105), and Prussian blue with yellow prussiate of potash. IRON MORDANTS. 119 A preparation of iron extensively employed at some print-works in the place of the common acid pernitrate, is a mixture of the neutral pernitrate with free acetic acid, obtained by adding- about a pound of powdered acetate of lead to two pints of a solution of the pernitrate, of the density 1-55. The acetate of lead is decomposed by the free nitric acid present in the solution, with formation of nitrate of lead, which is precipitated, and free acetic acid. A solution of a sub-pernitrate of iron, made by adding a small quantity of an alkaline carbonate to the pernitrate, is also sometimes advantageously sub- stituted for^ the pernitrate prepared as above. The peroxide of iron at first precipitated may be redissolved on agitation, if only a small proportion of al- kali has been applied. Two other forms of peroxide of iron have been occasionally employed as mordants ; one analogous in its chemical constitution to basic alum, and the other to red liquor (page 113). The first is prepared by partially de- composing, by means of an alkaline carbonate, the persulphate of iron, made by boiling copperas in dilute nitric acid. The oxide at first precipitated by the alkali is slowly redissolved by the undecomposed persulphate, giving rise to the subsulphate of the peroxide. The preparation of peroxide of iron, analogous to red liquor, may be made by adding one part, by weight, of ace- tate of lead to four parts of a solution of persulphate of iron of the density 1-65. Sulphate of lead is precipitated, and the solution comes to contain sub- sulphate of the peroxide of iron, and peracetate of iron or free acetic acid. A patent has been recently obtained by Mr. Mercer and Mr. Barnes for the preparation of an acidulous liquid for mixing with ferruginous mordants, which imparts considerable brilliancy to the leints of all compounds of color- ing matters (particularly that of madder) with peroxide of iron. This liquid, known as " assistant mordant," or " patent purple liquor," is niade by digest- ing farinaceous substances, starch, or sugar, in warm nitric acid, of moderate strengtli. The temperature of the mixture is not allowed to become high, in order to prevent the formation of oxalic acid. When all the nitric acid pres- ent is decomposed, a little pyroligneous acid is added, and the mixture is then ready for use. For producing a black dye, with oxide of iron and madder, one measure of iron liquor may be mixed with one or two measures of " assistant ;" for light purples, the proportion of " assistant" may be increased to five or six meas- ures. The beneficial action of this preparation is considered to consist chiefly in the retardation of the peroxidizement of the iron mordant during the "ageing." The enlivening action of strong acids and acidulous salts on the teints of some vegetable and animal coloring matters, when applied in a diluted state to the compounds of coloring matters and mordants, is a subject which de- serves the particular attention of the dyer and calico-printer. Instances of this effect of the application of acids, either to the dyed cloth or to the infu- sion of the coloring matter, are of frequent occurrence ; and some bright shades of color can not be obtained without the assistance of an acid, though the mode of action of the acid is by no means obvious. If a piece of cotton is printed or padded with iron liquor, dunged, winced in a mixture of chalk and hot water, and then dyed in a decoction of valonia or other vegetable matter containing tannin, it acquires merely a dull drab color. But if the cloth thus dyed is exposed for a short time to the fumes of hydrochloric acid, or if winced in very dilute sulphuric or hydrochloric acid, the color of the cloth changes from drab to slate color or black, according to the quantity of mordant on the cloth. Acetic acid produces the same effect, but not in so powerful a manner as sulphuric acid, of which a mere trace is as effective as a. much larger quantity. The color of the compounds of both oxides of tin (but especially that of the protoxide) with the coloring matter of logwood may also be greatly enlivened by the application of very dilute 120 DYEING AND CALICO-PKINTING. sulphuric acid, and a good scarlet or crimson can not be obtained from cochi- neal with a tin or aluminous mordant without the introduction of tartaric or oxalic acid or cream of tartar. That the mode of action of the acid in such cases varies with different col- oring matters and mordants hardly admits of doubt. The quantity of acid required in some cases is far too small to warrant the supposition that it en- ters into a permanent chemical union with the coloring matter and mordant ; but in other cases a sensible quantity of acid disappears, and seems to enter as an essential constituent into the composition of the coloring material. In cases where the acid does not enter into a permanent chemical combi- nation with the mordant and coloring matter, it may be considered to act in two ways : — 1. By preventing the deposition of an excess of the coloring matter on the mordanted cloth, or by removing such an excess, if already deposited, through its solvent power ; 2. By effecting the disintegration of ihe particles of the mordant, whereby the latter is enabled to form a more intimate combination with the coloring material. When a piece of cotton cloth impregnated with a mordant in the ordinary manner is imimersed in the dyeing decoction, it often absorbs more coloring matter than is necessary to form what may be considered as the neutral com- pound of coloring matter and mordant. But this excess of the coloring prin- ciple is frequently prejudicial to the teint of the compound of the mordant with a smaller proportion of coloring matter, with which the excess is in a state of loose combination, being held, probably, by a mere attraction of sur- face (see page 97), and not by chemical affinity. Thus the compounds of both oxides of tin with an excess of the coloring matter of logwood are con- siderably inferior in vivacity of color to the compounds of the same oxides with a smaller proportion of the coloring matter. The dulness of the color of a piece of cotton mordanted with iron liquor, dunged, winced in hot chalky wa- ter, and died in a decoction of valonia (see page 119), may be attributed to the deposition of an excess of tannic acid (which is the astringent principle of the valonia) on the neutral and darker colored tannate of iron. Now one effect of the application of a small quantity of a strong acid to the decoction of the dye-stuff, may be the prevention of the attachment of this ex- cess of coloring matter to the mordanted cloth ; an acidulous liquid being generally a more powerful solvent of the coloring principle than pure water ; and a corresponding effect may take place when the dyed cloth containmg an excess of coloring matter is exposed to an acidulous liquid, the excess being then partly removed from the cloth, through the solvent power of the acid. But a more important effect to be attained by the application of an acid is the disintegration of the mordant on the cloth, whereby the interior particles of the mordant become placed in a better condition for combining with and retaining the coloring matter. During the drying of a mordanted piece of cotton, the mordant always becomes more or less aggregated ; and if the cloth is exposed to a high temperature, the aggregation may become so great with some mordants that very little colorin;^ matter is absorbed when the cloth is immersed into the dyeing liquid containing no free acid. A remarkable dif- ference may be observed between the quantity of the coloring matter of log- wood absorbed by a piece of cotton impregnated with either perchloride or protochloride of tin, and dried at a very gentle heat, and the quantity of the same coloring matter absorbed by a piece of cloth containing the same mor- dant, but dried at as high a temperature as the cloth will well support. Even two pieces of cotton containing similar quantities of the same tin mordant, both dried at a low heat, but one washed in cold water after being dried, and the other in hot water, present a very sensible difference in shade when dyed in the same infusion of logwood. It is difficult to conceive how such effects are produced, except through differences in the state of aggregation of the mordant on the cloth. But the addition of a small quantity of sulphuric acid to the dyeing liquid, ACTION OF ACIDS ON COLORING MATTERS. 121 causes the production of a uniform and bright color in both pieces of cotton, whether dried at a high or low heat, or washed in hot or cold water. A mere trace of acid is generally sufficient to produce this effect, hence it can not be supposed to act in all cases by forming a permanent chemical combmation with the coloring material. , , , u The disintegration of the precipitated mordant on the cloth seems to be the principal effect of the application of an acid in such cases as those now under consideration. The interior, uncombined, particles of the mordant thereby become exposed, and placed in a condition to unite intimately with the color- ing material, the latter being derived either from the dyeing liquor or trom the excess in loose combination with the exterior particles of the mordant. The disintegration of the mordant by the acid may possibly be a mere mechani- cal effect,* independent of any chemical alteration of the mordant, but the action of the acid admits of a more satisfactory explanation. The precipitated mordant is probably first dissolved by the acid, but is immediately reprecipi- tated in intimate combination with the coloring matter ; the acid thereupon be- comes liberated, and enabled to act in the same manner on other portions of the mordant. Whether the acid be mixed with the dyeing infusion, or applied as an alterant (see page 110) to the dyed cloth containing an excess of coloring matter, its action is of the same nature. An illustration of this principle is afforded by an experiment before referred to, which consists in exposing to the diluted fumes of muriatic acid a piece of cotton, with oxide of iron as the mor- dant, dyed to a drab color in infusion of valonia (see page 119). The tannm or the astringent principle of the valonia is united only with the exterior parti- cles of the oxide of iron, but is there contained in excess ; on the applicalion of the acid both the excess of tannin and the interior particles are dissolved, brought into contact, and precipitated in intimate combination, the muriatic acid being liberated to act on other portions of oxide of iron and tannin in a similar manner. , i i_ v The preceding explanation of the enlivening effects produced by the appli- cation of acids to compounds of organic coloring matters and mordants, refer only to those cases in which the quantity of acid sufficient to produce the effect is too small to warrant the supposition that it enters into a permanent chemical combination with the coloring material. In other cases a sensible quantity of free acid unites with the compound of mordant and coloring mat- ter, and modifies the properties of the latter by causing a new disposition of its particles. , • i • . -j That the purple compound of the coloring ma iter of cochineal with protoxide of tin, for example, is capable of uniting with free sulphuric acid appears evident from the following experiment, communicated to me by Mr. Mercer. When a solution of protochloride of tin is added to a decoction of cochineal, a purple lake is precipitated, consisting of a compound of the coloring matter of cochineal with protoxide of tin mixed with an excess of the protoxide. Ihis lake is collected on a filter, carefully washed with distilled water, and Jigested in a given quantity of a solution of carbonate of soda of known strength. The proper compound of coloring matter and oxide of tin then dissolves in the alkaline carbonate, and the excess of oxide of tin remains undissolved. On mix- ing an excess of sulphuric acid with the alkaline solution the pure lake is reprecipitated of a much richer color than before being thus treated ; but the reprecipitalion of the pure lake requires considerably more acid than is necessary to neutralize the alkali. None of the lake is thrown down if no more acid is applied than the quantity exactly necessary for the neutralization ; but on adding more, the precipitation immediately commences, though no tree acid can be detected in the mixture until the lake is completely thrown down. It is difficult to determine precisely the nature of the modification which coloring matters, or compounds of coloring matters and mordants, experience by combining with an acid in such a case as the preceding ; some considera- * Examples of the disintegration of precipitates, by being digested in an acid liquid, which exerts no chemical action on the precipitates, are by no means rare. Thus, an intimate mixture of pure Prussian blue with hydrochloric acid appears to become a perfect solution on standing ; but tlie particles of the pigment are merely disintegrated, and still exist in an insoluble form. 122 DYEING AND CALICO-PRINTING. tions on this subject, however, may not be without a practical application in the operations of the dye-house. Soluble vegetable and animal coloring matters have the property of uniting both with acids and bases : with acids, they form feeble combinations pos- sessed of lively teints ; but with bases, they afford stronger combinations, hav- ing less vivacity of color. In general, the more closely a mordant resembles an acid in its chemical character, the brighter are the teints of its compounds with coloring materials. Thus, peroxide of iron and peroxide of tin, which appear to act the part, sometimes, of feeble acids, produce compounds with coloring matters having brighter colors than similar compounds with protox- ide of iron and protoxide of tin. But metallic protoxides, which possess a greater basic power than their corresponding peroxides, generally form more intimate combinations with soluble organic coloring materials, than the per- oxides, especially if the protoxide is of itself a stable substance, as protoxide of tin. Some metallic protoxides also unite with a larger quantity of coloring matter than peroxides, but it is uncertain whether the excess is held by chem- ical affinity or by a mere attraction of aggregation dependant on the slate of the surface of what we may consider as the neutral compound of coloring matter and mordant. For tissues which can combine with and retain strong acids without injury to the fibre, as wool and silk,* protoxide of tin is as suitable a mordant as the peroxide, because the brightening effect which the mordant fails to produce may be obtained by the application of an acid. For this purpose, oxalic acid is frequently applied to woollen goods containing protoxide of tin as the mor dant. But as very few strong acids can be applied to cotton goods without weak- ening the fibre to a greater or less extent, it becomes necessary, in order to ob- tain bright colors, to apply such mordants only as possess some resemblance to acids, as alumina, and the peroxides of iron and tin. In the action of such bodies on soluble organic coloring materials two forces may be recognised : by one, the mordant acts as an acid, producitig an enlivening of teint ; by the olher, it acts as a base, producing an intimate and stable combination. DUNGING. As the precipitation of the mordant in the form of an insoluble subsalt du- ring the hanging or " ageing" of cotton goods is never complete, it becomes necessary to remove the unpreqipitated mordant from the cloth before the dye- ing, else a quantity of superfluous coloring matter will be deposited on the surface of the cloth, which would have to be removed by subsequent opera- tions, besides causing an unnecessary impoverishment of the dyeing liquid. But the necessity for renaoving the superfluous mordant is chiefly experienced with cotton goods on which the mordant is printed so as to produce a pattern. If all the mordant which remains in a soluble form is not completely removed from such goods, a portion of it may become distributed over the whole sur- face of the cloth when the pieces are washed in water or put into the dye- beck. One process for effecting the complete removal of the unprecipitated mor- dant consists in simply drawing the dried goods through a warm emulsion of cow-dung and water. The emulsion is usually contained in two stone cis- terns, each about six feet long, by three feet wide, and four feet deep : that in one cistern contains about two gallons of dung, to the cistern-full of hot water that in the second contains only half this proportion of dung. The cloth, on being taken from the " ageing"-room, is first drawn pretty quickly through the emulsion containing most dung, and immediately afterward through the other the cisterns being usually placed end to end, to allow the cloth to be conducted * If silk and wol are digested in dilute sulplmric or muriatic acid, a portion of the acid combines with the stuffs, and the liquid is found wealior after than before the immersion. The animal tissues also combine with tartaric acid when digested in a sulution of cream of tartar (bitartrate of potash), leaving neutral tartrate of potash behind. But cotton exhibits no such disposition to unite with acids, and when digested in dilute sulphuric or muriatic anid, abstracts the water in preference to the acid, thus making the liquid more acid than before the immersion of the cotton. DUNGING— COMPOSITION OF COW-DUNG. 123 directly from the first to the second. The cloth is guided in its passage through the cisterns by four or five rollers placed at each end, it being essential to the success of tills operation that the pieces should be extended and free from folds. Immediately on issuing from the second cistern, the cloth is passed over the reel of a contiguous wince-pit (see figs. 31, 32, page 127), where it is well washed in clean water, and from the wince-pit it is generally taken to the dash-wheel. If the mordant on the cloth is the aluminate of potash, some muriate of ammonia is added to the dung emulsion, to ensure the precipita- tion of alumina, which it%lfects by a reaction explained at page 116. Occa- sionally, the cloth containing aluminate of potash is passed through a solution of muriate of ammonia before it is exposed to the dung emulsion. In calico-printing, the dunging process is necessary for all kinds of alumi- nous, iron, and tin mordants, when applied to the cloth before the coloring matter. The time of immersion, the temperature of the mixture, and the number of pieces which may be passed through a given quantity of dung and water, depend entirely on the state and quality of the mordants, and on the nature of the thickeningpaste by which the mordants are applied. A piece of cotton with a mordant which has a strong acid requires a longer time than a piece the mordant on which has a weak acid ; and when the thickening paste for a mordant is flour or starch, a higher temperature is required than when British gum or common gum is used. The usual temperature of the dung emulsion is 160° or 180° Fahr. Dunging is one of the most important steps in the process of calico-printing ; and if badly performed, especially when the mordant on the cloth is alumina, the success of the subsequent dyeing is sometimes greatly endangered. The operation has for its object, not merely the removal of the superfluous mordant, and in printed goods of the thickening paste by which the mordant is applied, but the deternunation of a more intimate union between the mordant and the stuff, which it seems to effect by converting the sparingly soluble subsalts on the fibre into other compounds, perfectly insoluble. Although the objects of the operation of dunging are sufficiently obvious, yet the precise manner in which they are attained is involved in some uncertain- ty. According to an analysis by "M. Penot, cow-dung contains the following ingredients in 100 parts. COMPOSITION OF COW-DUNG. Woody fibre 26-39 Albumen 0-63 Chlorophyl 0-28 A sweet substance 0*93 A bitter matter 0-74 Chloride of sodium 0'08 Sulphate of potash 0-05 Sulphate of lime 0-25 Carbonate of lime 0*24 Phosphate of lime 0-46 Carbonate of iron 0-09 Silica 0-14 Water 69-58 (Loss 0-14) 100-00 It is generally admitted that the superfluous or unprecipitated mordant is immediately dissolved by the hot water; but instead of remaining in a state of solution it is entirely precipitated in an insoluble form, partly by the albumi- nous constituent of the dung, partly by the phosphate and carbonate of lime, and partly by the insoluble ligneous fibre, and is therefore rendered incapable of attaching itself permanently to the cloth. But it appears that a small por- tion ot'the superfluous mordant dissolved from the cloth by the hot water, in- 124 DYEING AND CALICO-PRINTING. stead of being afterward precipitated, is permanently retained in solution in a peculiar state of combination with the animal matter of the dung; one of the characters of which combination is, that it is incapable of afiording a precip- itate of subsalt or oxide to the cloth. The precise nature of this compound of the mordant with organic matter is not known, but it is believed to be anal- ogous to that of several soluble combinations of metallic oxides with organic matters which are not affected by certain chemical reagents in the same man- ner as ordinary salts of such oxides. Thus, a salt of the protoxide of copper in the presence of several organic substances, sugar for instance, is not precip- itated by a solution of a caustic alkali ; the double tartrate of the peroxide of iron and potash does not afford a precipitate of peroxide of iron when mixed with a solution of caustic potash, nor does it yield a subsalt to cotton, like most other ferruginous salts. The constituents of the dung which appear to be principally concerned in the fixation of the mordant on the cloth are the albuminous and soluble vegeta- ble matters and the phosphate of lime. The former act partly by uniting with the base of the subsalt on the cloth, liberating its acid and forming a new com- bination more insoluble than the previous subsalt. The liberated acid may soon be detected in the liquid by the test of blue litmus paper, and requires to be neutralized, in a few processes, by the introduction of chalk.* The al- buminous matter of the dung seems" also to exercise an influence as a deter- gent or an emollient, whereby it considerably facilitates the detachment of the loosely combined mordant. The action of the phosphate of lime in the dung emulsion is to cause the formation on the cloth of phosphate of alumina or phosphate of iron by a double decomposition, the acid in the subsalt uniting at the same time with the lime of the phosphate. Both phosphate of iron and phosphate of alumina are quite insoluble in water, and also in acetic acid, if warm. Within the last few years the dung emulsion has been superseded, either partially or entirely, in all well-conducted print-works in Great Britain, by a solution of phosphate of soda and phosphate of lime, known by the name" of "dung substitute," or simply " substitute," for the preparation of which a pat- ent has been obtained by Mr. Mercer, Mr. Prince, of Lowell, Massachusetts, and Mr. Blyth. A solution of an alkaline arseniate had been long previously used as a substitute for dung by Mr. Mercer. Dung substitute is prepared by mixing sulphuric acid with bone-earth, which consists chiefly of phosphate of lime ; the acid not being applied in sufficient quantity to decompose the phosphate of lime entirely, but to pro- duce an acid phosphate, or a solution of the phosphate in free phosphoric acid. Carbonate of soda is then added to neutralize the free acid completely, and the mixture is evaporated until the residuary mass becomes almost dry. When the concrete thus obtained is mixed with water, it affords a solution of phos- phate of soda containing some phosphate of lime : a white mud remains un- dissolved, consisting of sulphate, carbonate, and a little phosphate of lime, which should be carefully stirred up when the liquid is about to be used. This preparation is not, of itself, an eflScient substitute for all the essential, or at least for all the important constituents of the dung emulsion. To supply an emollient and detergent substance in the place of the albuminous matter of the dung, it is found necessary to mix with the above liquid a solution of glue or some other form of gelatine. The material employed for this purpose in most print-works is a solution of bone-size, called " cleansing liquor," which is made by boiling bones in water for nearly a week, separating the fat which rises to the surface of the liquid, and evaporating the aqueous solution of gel- atme until it attains a density about 36° Twaddell (1-180). The advantage of making this addition to the phosphates was first pointed out- by Mr. Mercer. When the " aged" cloth is passed through a mixed solution of substitute * On the Continent, it is a common practice to add to the dung emulsion, in all cases, either chalk or bicarbonate of soda, the latter being- preferred ; but it is unusual in this country to make any such addition to the dung, except in cases where the clotli contains a free acid or acidulous salt, as lemon-juice or bisulpbate of potash. The smallest excess of an alkaline carbonate shoulf be avoid- ed when alumina is the mordant on the cloth. DUNG SUBSTITUTE— DUNGING. 125 and gelaline, the latter greatly facilitates the separation of the loosely-com- bined mordant, and prevents its reattachment, while the phosphate of lime and phosphate of scua in the former serve to fix the alumina and oxide of iron in more intimate combination with the stuffs by converting them into phos- phates. The acids previously in combination with the alumina and oxide of iron (when these bases existed as subsalts) unite at the same time with the soda and lime of the substitute. The following detailed account of the best mode of applying the solution of subsiitute to mordanted goods has been communicated to me by Mr. Mercer. It refers to cases in which dung is entirely dispensed with, and in which the mordant is applied to the cloth topically. The cloth is exposed to the action of two solutions of the substitute consec- utively ; that first applied, which is considerably stronger than the other, may be contained in a common dung-cistern capable of holding not less than six hundred gallons, and furnished with a series of rollers, so as to allow the im- mersion of fifteen yards of cloth at the same time. The weaker solution of substitute is applied to the cloth in a wince-pit. A normal solution of substitute, called " substitute liquor," is first made by dissolving the substitute in warm water at the rate of two pounds to the gal- lon. Six gallons of this substitute liquor and two gallons of the cleansing liquor are introduced into the cistern, which is then filled with hot water, and the pieces of cloth are passed through at the rate of thirty yards per minute. The temperature of the solution may be the same, in general, as that of the dung-beck, in tiic common dunging process : for madder purples and pale reds it should never exceed 140° Fahr., but for madder blacks and full reds it may be a little higher. This cistern requires to be frequently renewed by the addi- tion of fresh quantities both of substitute liquor and cleansing liquor. A gal- lon of the former and a quart of the latter may be added for every thirty or fifty pieces, according to the " heaviness" of the work, -or the quantity and strength of the mordant on the cloth. "When removed from the first cistern, the pieces are well washed in water ;* after which they are winced in the weaker solution of substitute. This so- lution may be contained in a wince-pit or cistern capable of holding about three hundred gallons, with which quantity of hot water there should be mixed two quarts of substitute liquor and one quart of cleansing liquor. In this liquid twenty-eight or thirty pieces are winced for twenty or twenty-five minutes, at a temperature about 10° lower than the solution first applied. The second cistern requires to be renewed by the addition of two' pints of sub- stitute liquor and one pint of cleansing liquor for every twenty-eight pieces. Both this and the first cistern should be fresh charged every morning, and emptied at night. The only remaining operation to which the pieces are subjected, previous to being dyed, is a thorough washing in water ; and if the work is heavy, they should also be passed between the squeezing-rollers, and again washed. Where the use of dung is only partially superseded by that of the substitute, tlie pieces are sometimes first passed through the common dung emulsion and afterward winced in a weak solution of substitute mixed with cleansing liquor or glue ; or the pieces may be first passed in the ordinary manner through a mixture of half the usual quantity of dung with half the above proportions of substitute liquor and cleansing liquor, and be afterward winced in a solution of substitute of the same strength as the second applied as above without any dung. For madder reds, the mixture of dung and substitute seems to be more advantageous than substitute or dung alone ; but for madder purples and black a preference is given to the use of the substitute only. The expj iire to dung or substitute* of cloths mordanted with alumina, should not be pr j!. !U f;d a sufficient time to allow of the unioii of the alumina with a full proix r: io 1 jf phosphoric acid ; for coloring matters do not readily displace phosphoric acid from such a combination. The phosphate of iron, on the contrary, is i- isily decomposed by coloring matters. * If the work is iieav/, it is also recommended to pass them between the squeezing-rollers and again wash them in water. 126 DYEING AND CALICO-PRINTING. In a few dyeing processes where it is of importance to avoid the aggrega- tion of the particles of the mordant as much as possible, the pieces, instead of being exposed to dung or substitute, may be winced in a mixture of chalk and size with hot water. In this case, the chalk serves to fix the mordant on the cloth by withdrawing the small quantity of acid remaining in the subsak; and the loosely-combined mordant separated by the water is precipitated by the chalk, and thus rendered incapable of attaching itself to the fibre. If the goods contain an aluminous jnordant, the process of wincing in chalky water should not be prolonged, and only a small proportion of chalk should be em- ployed, as the precipitaLed alumina itself is apt to be removed by the action of an excess of chalk. The dunging process is sometimes superseded by the operation of hrammio-, which consists in wincing the goods in a mixture of bran and hot water. Th'e action of bran is probably quite analogous to that of dung, the unprecipilated mordant dissolved by the water being separated from the liquid by the insol- uble ligneous matter, while the undissolved mordant becomes more strongly attached to the cloth by combining with the mucilaginous and glutinous mat- ters present, and also with the phosphoric acid of the phosphate of lime in the bran. The only cases in which branning is preferred to dunging are those in which the cloth is afierward dyed to delicate shades of color bv means of cochineal and fugitive coloring matters. After having been thus exposed to the action of either dung, substitute, chalk, or bran, the mordanted goods are ready to be exposed to the infusion of the dye-stuff; and in general, the sooner this is done, the better is the col- or they assume. The different vegetable coloring matters vary so considerably in properties, that few observations of general application can be offered on the modes of preparing the various dyeing liquids. If the substance is very soluble, its so- lution may be made, in the cold ; but if only slightly soluble, heat may be ap- plied, provided the color is not deteriorated by exposure to a moderate heat. When a highly-charged solution is required (such as the topical and steam colors used in calico-printing), concentration by evaporation is had recourse to ; many vegetable colors, however, will not support a continued ebullition with- out losing something of their color. If the goods are not kept in consiant mo- lion when in the dye-beck, the infusion should be freed from the insoluble lig- neous matters by decantation or filtration ; in some cases this operation may be avoided by enclosing the tinctorial matters in bags, which are withdrawn from the liquid when sufficient color is imparted. But if the goods are kept in continual motion in the vegetable infusion, as is almost always done with cottons, the separation of the insoluble matters is unnecessary. The vegeta- ble material is commonly introduced in a state of coarse powder into the dye- beck containing cold water ; the pieces of mordanted cotton to be dyed are put in at the same time, and the temperature of the liquor is gradually in- creased by the introduction of steam. In the dyeing of cottons, motion may be communicated to the goods, while in the dye-beck, by a wince or reel placed horizontally over the middle of the dyeing vessel, so that the cloth may be made to descend into either compart- ment of the dye-beck by the rotation of the reel. The dyeing vessel, which is commonly constructed of wood,* is rep- resented in cross and longitudinal section at figures 31 and 32: a is the reel, containing six long wooden spars on its circumference ; it is set in motion by being connected with one of the driving shafts of the factory. Sieani is admitted to the vessel by the pipe b, the upper surface of which has a great number of small perforations. Twelve, eighteen, or twenty-four pieces of cotton, which are stitched together at their ends so as to form one endless web, pass over the reel in the direction of the arrows, and fall on a sloping iron ledge g, on one side of the vessel, from which they pass under the two rollers c and d. Four, five, or more of such endless webs may be set * For madder work, dye-becks made of iron have been lately substituted for those of wood. When tlie metal is completely covered with oxide, it exerts no injurious action on the colorine matter. ^ DYE-BECK. 127 Fig. 31. Fig. 32. in motion by the same reel, they being prevented from entangling by wooden bars represented at e, which reach from a cross-bar at the top of the vessel to the back. An inclined partition, /, extends through the whole length of the dyeing vessel, formed of several wooden spars placed a few inches apart from each other. The ordinarj' dimensions of the dyeing vessel, are six feet in length, fpur feet in width, and four feet in depth. Such is a general view of the course of operations practised in the dyeing of goods with coloring matters, which are naturally soluble in water, by the intervention of a mordant. If the coloring principle is insoluble in water, the mordant may be dispensed with ; but it then becomes necessary to devise some means of obtaining such a solution of the coloring substance as will al- low the deposition of the latter in its insoluble state, when a cloth impregna- ted with the solution is exposed to some chemical agent. This forms the third style of dyeing in the classification proposed at page 107. The principal in- soluble vegetable coloring materials are indigo, safflower, and annatto, the na- ture of the processes for applying which to cloth has already been explained (page 100^. The only other style of dyeing which remains to be noticed is entirely dif- ferent from either of the preceding; it is practised only on goods formed of the animal tissue, and admits of no more than one example in illustration. By this style, an orange color is imparted to silk and wool, not from the solu- tion of a coloring matter, but by effecting a certain chemical change in the fi- bre, through the action of dilute rutrie acid. The orange color is due to a substance formed by the decomposition of a portion of the silk or wool itself by the acid. The temperature of the dye-heck at the time of dyeing depends almost en- tirely on the nature of the coloring matter. If it is readily attachable to the tissue, as indigo and coloring principles derived from metallic substances, for instance, and if easily altered by heat, as safflower, the dyeing solution may be used cold. But a hot liquid generally affords the most uniform color, partly oa account of the more ready disengagement of air-bubbles from be- tween the fibres of the cloth. Dyeing with vegetable and animal coloring rnatters which require a mordant, is also effected more rapidly with the as- sistance of heat, owing to the increased disposition of the mordant to unite with the coloring principle. In a few dyeing processes, however, where the mordant exists on the cloth in a soluble state when about to be dyed, a high temperature in the dye-beck is injurious, from the separation of a portion of the mordant from the cloth by the solvent action of the dyeing liquor. Hence it is that cotton, silk, and flax, impregnated with alum, absorb more coloring matter from some solutions at the ordinary temperature than at the boiling point. Where the operations are conducted on anything approaching a con- 188 DYEING AND CALICO-PRINTINa. siderable scale, the most convenient and the most economical source of heat for the dye-beck is steam, which may be applied in three ways: 1°, by intro- ducing it directly into the liquid by a pipe leading from the boiler ; 2", by causing it to circulate through a spiral pipe placed in the dye-beck ; and 3°, by introducing it between the dye-copper and an exterior wooden case. The vessels in which the dyeing decoctions are made and concentrated by evaporation, are usually of copper ; for some delicate dyes, when a steam heat is applied, they are made of tin or of copper tinned inside. Copper boilers sometimes exercise considerable influence on the teints of the decoctions pre- pared, in them, owing to the solution of some oxide of copper from the surface of the metal, by an acid existing either in the mordant or the dyestuff. A solution of alum which has been boiled for some time in a copper vessel, affords with ammonia a blue instead of a white precipitate; and wool acquires a greenish-gray teint when kept for some hours in a boiling solution of alum with cream of tartar contained in a copper vessel, which would not happen with the same solution in a vessel of tin. In general, the vegetable and animal fibres become colored much more readily when unspun than when wove into cloth. Wool in flocks, after having been washed, digested in an alkoline ley, and bleached by sulphurous acid, takes more color than when spun into yarn, and the yarn more than when wove into cloth. This doubtless arises from the comparative difficulty with which the solution of the coloring matter obtains access to the internal fibres of the spun or woven tissue. The color of the interior of a piece of thick woollen cloth dyed in the piece, is often less intense to the eye than the color of the exterior. Certain disadvantages, however, sometimes attend the dyeing of wool in flocks and in thread : some colors, for instance, are susceptible of alteration in the subsequent manipulations in weaving ; the texture of the fibre is sometimes altered so as to present inconveniences in these operations, and it is more expensive from the subsequent waste of some of the material. The routine of finishing operations practised on cloths after being dyed, is varied considerably, according to the style of work and the nature of the stuff operated on. When the goods have remained a sufficient length of time in the dye-beck, they are removed and carefully washed in water to separate the colored liquid retained mechanically between the fibres. The drymg of the washed goods, if silk and wool, is usually effected by exposure to the air at common temperatures; but occasionally heat is applied, the gopds being introduced into a well-ventilated apartment heated by the circulation of steam- pipes. The drying of goods dyed with delicate colors should always be per- formed in the shade. The following account of the course of finishing operations practised on calico printed and dyed according to the madder style, will afford a general view of the treatment of cotton goods after having been dyed by means of a vegetable infusion with the intervention of a mordant. Some of the opera- tions here noticed are unnecessary, however, in other styles of dyeing and printing. Immediately contiguous to the dye-beck are usually placed two stone cisterns containing cold water, each surmounted by a reel, similar to that shown in tigs. 31 and 32. In one of these cisterns the cloth is washed as soon as it is taken out of the dyeing liquor, motion being communicated to the cloth by means of the reel." From the first cistern the pieces are transferred to the second, containing clean cold water, and from thence to a washing vessel of particular construction, called the dash-wheel (tig. 33). This is a hollow, circu- lar, perpendicular wheel of five or six feet in diameter, and nearly two feet in depth, divided into four equal compartments by partitions proceeding from the axis to the circumference, each of which has a circular opening on one face of the wheel. Water is admitted into the compartments by a pipe concentric with the axis on which the wheel rotates. The pieces of cloth to be washed are put into tlie compartments through the circular openings in front, and water being admitted, the wheel is made to rotate rapidly, and thus wash the doth with considerable agitation. FINISHING OPERATIONS. 129 In the washing of cloths which require delicate treatment, as those dyed with fancy or spirit colors, for which the action of the dash-wheel is much too energetic, another washing apparatus is employed, called the rinsing machine, an idea of the ordinary construction of which will be afforded by the represen- tation of its longitudinal section at fig. 34. It consists of a rectangular wooden cistern of from twenty to thirty feet long, three feet wide, and four feet high at one end, and three feet high at the other. The cistern is divided transverse- ly into from six to ten compartments, by partitions which gradually decrease Fig 34. in height from the higher to the lower end of the vessel. In each compart- ment except the highest, are placed three rollers, to regulate ihe passage ot the cloth through the cistern, two of the rollers being near the bottom and the other at the top. Above each partition are placed two more rollers nearly in contact ; and those above the higher end of the cistern and the first parti- tion are squeezing rollers subject to considerable pressure, and worked by machinery connected with one of the driving shafts of the factory. The pieces of cloth to be washed are introduced into the cistern at the lower end, and traverse each compartment successively, being drawn through by the traction of the squeezing rollers at the upper end. A stream of clear water is made to flow into the cistern at the higher end and out at the lower, while the cloth is passing in the opposite direction ; by which arrangement the cloth is brought successively into contact with purer portions of water and is discharged at the top perfectly clean. In the machine represented in the above figure, the water flows from one compartment into another through apertures near the tops ot the partitions, and not over the partitions. In another form of the rinsing machine, the water passes from one compartment into the next through aper- tures at the tops and bottoms of the partitions alternately. It is to be obser- ved that this machine is used only for goods which require more delicate treat- ment than is compatible with the dash-wheel or the wmce-pit. While the cloth is in the dye-beck, a considerable quantity of coloring mat- ter attaches itself to the surface of the cloth, not in chemical combination with 9 130 DYEING AND CALICO-PRINTING. the mordant, but too strongly attached to be easily removed by washing in clean water. To get rid of this superfluous color, the cloth, after having been washed at the dash- wheel, is winced either in a mixture of bran* and boiling water, containing about a bushel and a half of wheat bran for every ten pieces of calico, or else in a dilute solution of soap. The addition of a little caustic alkali to the soap or bran is sometimes made ; but neither an alkali nor soap can be used for this purpose without great care, as the teints of all vegetable colormg prmciples are slightly deteriorated by these agents. For most vege- table coloring matters besides madder, bran only is admissible ; and even in bran-water, the wincing sometimes must not exceed a few minutes. With madder colors only, the wincing mav be continued for from ten to twenty minutes. The complete removal of the superfluous color from a piece of cloth which IS to present a white pattern is generally eff'ected, when madder is the only vegetable coloring matter present, by wincing the cloth for a lew minutes in a solution of chloride of lime, not stronger than 3° Twaddell (1015). This operation usually follows that of branning or soaping, but sometimes the bran- ning is altogether omitted when the solution of chloride of lime is employed. Few vegetable coloring matters, however, can be exposed to the action of chloride of lime without considerable deterioration ; hence, when other dye- stuffs than madder are employed, the " clearing" of the dyed cloth is effected, sometime by exposure to air and light, but the process of branning or soaping is generally found to be suflUcient of itself. After having been thus cleared of the redundant color, the cloth is washed, and then submitted to an operation for expelling almost the whole of the water it contains ; which consists either in passing it between two rollers revolving against each other under considerable pressure (squeezing rollers), or else in rotating the cloth so rapidly as to cause the water to be driven out by the centrifugal force thus excited. One of the machines used for the latter pur- pose is represented in perpendicular section across the centre at fig. 35, and as Fig. 36. Viewed from above in fig. 36 : a and 5 are two copper cylinders connected ^gether at bottom so as to form one vessel, which rotates with the axis c. These cylinders are enclosed in a wooden case d, which is in communication, at bottom, with a drain or gutter. The cylinder b has a great number of small perforations, and is divided by partitions into four equal compartments. The wet cloth which is to be dried is placed in the compartments between the two cylmders, and the apparatus is rotated with a velocity of nine hundred or a thousand revolutions per minute ; the water is thereby driven from the cloth through the perforations in the cylinder b to the outer case, whence it * In effecting the removal of this exce,ss of coloring matter, the most active constituent of the bran seems to be the husky part. The feebly combined coloring principle dissolved by the hot water and the mucilaginous matters present, mstead of being retained in solution, is precipitated on the *^f7 l^^s prevented from agam attaching itself to the cloth. Coarse bran is better adap- i^L^ii « P"''P°«e than fine, and flour seems to be altogether useless. An interesting memoir by M. KoBchhn-Schouch, on the use of bran in this operation (termed " clearing"), is contained in the ninth volume of the Bulhttn de la Societe Indus tnelle de Mulhausen FmiSHING OPERATIONS. 131 Fig. 37. flows out by a gutter or drain. After a few minutes the cloth becomes nearly dry, and when the machine is opened, is found to be strongly compressed against the perforated cylinder.* In another form of this machine, which works with much less noise than the preceding, the cylinders are arranged vertically, so as to form an apparatus somewhat resembling the dash-wheel (fig. 33, page 129). When the cloth has been thus far dtied, either by the squeezers or the " water extracter" just described, it is folded evenly and then passed, in the length of ten pieces, through a mixture of blue starch and water. A cross section of the starching machine is represented in fig. 37 : a is a wooden trough to contain the mucilagin- ous liquid ; i is a small cylinder revolving in the liquid ; around this is passed the web of calico c, which is then drawn over a fixed brass bar d, with diagonal notches on its front, for the purpose of removing creases from the cloth; e is a wooden cylinder covered wilh clolh, revolving in close contact with the brass cylinder/; the calico is passed between these cylinders to be freed from the superfluous starch, and is then rolled off" upon the cylinder g, the axis of which is not fixed, but so con- trived as to recede gradually from the wooden cylinder as the roll of calico increases in diameter. After being starched, the ten pieces of calico are passed through the steam drying machine, which consists of several hollow copper cylin- ders, each about twenty inches in diameter and three feet in length, fitted up with ma- chinery by which^all the cylinders or drums may be rotated together at the same velocity. Steam is admitted to the drums through stuffuig boxes at one end of the axes, and at the other end are placed pipes to discharge the condensed |^ater. The number of drums arranged together in one system varies from Eve to thirteen, according to the quantity of work required ; they are some- times placed in one line, but usually in two lines, one immediately over the other (as fig. 38), with the circum- Fig- 38. ference of one drum distant about four or six inches from that of the next in the Ime of the axes of the drums. The calico passes through the machine in the direction of the arrow in the above figure. The drums are surmounted by a hood and flue for the purpose of conducting the stream out of the chamber. The last finishing operation to which dyed and printed cottons are sometimes subjected is calendering or giazmg, the object of which is to make the surface of the cloth smooth, com- pact, and uniform. This is efi'ected by passing the piece between two cylm- ders revolving in such close contact that their pressure gives the cloth the appearance of having been ironed. One of the cylinders is made of iron, and is hollow for the purpose of admitting steam or a hot iron rod, when the application of heat is necessary. The material of the other cylinder was for- merly wood, but for some vears past pasteboard has been very generally substituted. The cylinder of paper has several decided advantages over that of wood. It takes a finer polish, it has no tendency to crack or warp, and from having a certain degree of elasticity, it gives a more equal pressure on all parts of the cloth than could be applied by a wooden cylinder. The paper cylinder is * This machine is known by the name of " water extracter." 132 DYEING AND CALICO-PRINTING. constructed by placing circular discs of stout pasteboard on a square bar of wrought iron as an axis. The external discs are of cast iron, a little less in diam- eter than the remainder of the cylinder. The discs being screwed down tight, the cylinder is placed in a stove, and kept for several days at as high a tempera- ture as the paper will bear without being charred or rendered very brittle. As the 'moisture is driven off, the pastebo#d shrinks, and the screws must be tightened to keep the inass as compressed as possible. When no further dimi- nution in bulk is perceived, the cylinder is removed from the stove, and care- fully turned on a lathe. The diameter of the paper cylinder is usually four- teen inches, and that of the opposed iron cylinder eight inches. Four or five cylinders are commonly arranged together one over the other on the same frame. The ffl azing of calicoes was formerly executed by the hand with a hot iron, at an expense of about one shilling per piece of twenty-eight vards; the cost of glazing by machinery as above is from threepence to sixpence per piece. The purity of the water employed in dyeing operations is a subject which deserves the especial attention of the practical dyer. The finest colors are in almost all cases obtained by making use of distilled water, that being free from all earthy impurities. Eain water and the water of an Artesian well are, in general, better adapted for dyeing than spring water and river water, as the latter contain in solution a quantity of lime, which sometimes fall down in combination with the coloring matter as an insoluble precipitate, occasionmg a considerable loss of dye-stuff. Spring and river water also generally contain a sensible quantity of iron, which always communicates a brown tinge to the goods washed in such waters. When the yellowish Dutch madder is boiled with pure distilled or rain water, the residuary ligneous matter has a light brown color, and imparts only a faint red color to a boiling solution of alum. When, on the other hand, spring water is substituted, the residue is dark reddish-brown, and a solution of alum in which it is boiled becomes of a dark red color. In the first case, the quantity of madder red remaining the residue is much less than in the second. The madder red at first dissolved is precipitated by the lime of 1% spring water, imparting to the residue its dark color, and is dissolved by the boiling solution of alum. Hence pure water dissolves more madder red than water holding lime in solution. Similar results are obtained with Fernambouc- wood and logwood. (Dr. F. Runge, Farben-chemie.) In some print-works in Lancashire distinguished for their fancy styles, it is a common practice to add a little dilute sulphuric acid to the water, if the latter contains carbonate of lime. The sulphuric acid converts the carbonate mto sulphate of lime, which scarcely aff'ects the brilliancy of the colors of the dyed or printed goods. It is of importance that there should be no excess of the acid. When cochineal colors are washed, distilled water is usually em- ployed ; but where this can not be readily obtained in sufficient quantity, water treated with acid, as above, is used. These remarks are applicable to water containing calcareous matters only. Dr. Clarke's process for purifying water from carbonate of lime has not yet been introduced into the Lancashire print-works, but if efficiently conducted, it would no doubt be found highly advantageous. Water which infiltrates marshy ground often contains in solution a quantity of decomposed vegetable matter, which is also very detrimental to certain colors. Not only is the shade of color modified by the attachment of the organic matter, but certain metallic coloring materials, especially chrome- yellow and chrome-orange, are decomposed and converted into a brownish- black substance through the action of the organic matter. This proceeds from the generadon of soluble earthy or alkaline sulphurets through the decom- position of the soluble sulphates which spring water always contains ; the blackening of the chrome-yellow and chrome-orange is due to the formation of sulphuret of lead by the action of the soluble sulphuret thua produced. CALICO-PRINTING PROCESSES. 133 A simple and efficacious method of rendering hard water well adapted for dyeing operations is practised at the Dukinfield branch of the Mayfield print- works, Manchester, on all the water consumed there, which amounts to six or eight hundred thousand gallons daily. It merely consists in mixing the refuse of the madder dye-becks with the water ; the remaining coloring matters of the madder then precipitate the iron and lime in an insoluble form, and the water is obtained clear and fit for use by allowing the precipitate to settle in a large reservoir, and then filtering the water through a bed of gravel. At an extensive silk-dyeing establishment in London, the only water em- ployed is that raised from an Artesian well. In one dyeing process, however, namely, the production of a black color by means of infusion of galls, valonia, or sumach, and copperas, the water which is preferred by some dyers is hard spring water. To produce in a lie^uid a given depth of color, distilled water requires more dye-stuflf than common spring water. This is illustrated in the following experiment devised by Mr. Phillipps. Into two glass jars of the same size, each half filled with distilled water, introduce equal quantities of infusion or tincture of galls or sumach, and an equal number of drops (only three or four) of a solution of copperas. A faint purplish color will be developed in both jars ; but if one is filled with spring water, the color in that rapidly becomes dark reddish-black, and one half more water is required to reduce it to the same shade of color as the other. The water which is found by experience to be best adapted for dyeing with galls and sulphate of iron differs from distilled water in containing sulphate of lime, carbonate of lime held in solution by free carbonic acid, and chloride of calcium. The beneficial ingredient seems to be the carbonate of lime, which possesses slight alkaline properties ; for, if the smallest quantity of ammonia, or of bicarbonate of potash, is added to the distilled water in the above experi- ments, the purple color is struck as rapidly and as deeply as in the spring water ; chloride of calcium and sulphate of lime, on the contrary, produce no sensible change either in the depth of color or the teint. The effect is no doubt referable to the action of the alkali or lime on the protosulphate of iron, by which the sulphuric acid of the latter is withdrawn, and hydrated protoxide of iron set free ; for protoxide of iron is much more easily peroxidized and acted on by tannic and gallic acids (the dyeing principles of galls) when in the free and hydrated state, than when in combination with sulphuric acid. Neither the caustic fixed alkalies (potash and soda) nor their carbonates can be well introduced in the above experiments, as the slightest excess reacts on the purple color, converting it into a reddish-brown. Ammonia, lime-water, and the alkaline bicarbonates also produce a reddening, and if applied in con- siderable quantity, a brownish tinge. But the dyeing operations in which hard water is preferable to soft are so few in number, that the generality of the above statement concerning the superiority of soft water is scarcely at all affected. § IV. CALICO-PRINTING PROCESSES. Although the different methods of procedure in the printing of cottons are almost as numerous as the different kinds of patterns which may be produced, yet each color in a pattern is always applied by one of six different styles of work, by the proper combination of two or more of which the cloth may be ornamented with any pattern, however complicated. These styles are quite distinct from one another ; each requires a peculiar process and a diflFerent manipulation. The six styles alluded to are the following : — 1. Madder style, for soluble vegetable and animal coloring materials.—In this kind of work, which derives its name from being chiefly practised with madder, the thickened mordant is first imprinted on the white cloth in patterns, and after the cloth has been aged and dunged, the color is imparted by passing the cloth through the dye-beck. On those portions of the cloth on which the mor- dant is applied, the coloring matter attaches itself in a durable manner, but on 134 DYEING AND CALICO-PRINTING-. ihe unmordanted portions the color is feebly attached, so that it may be wholly removed by washing either in soap and water, in a mixture of bran and water, or in a dilute solution of chloride of lime. 2. Topical Style, for Steam and Topical Colors.— Such coloring matters as are incompletely, or not at all, precipitated from their solutions on being mixed with certain solutions of a mordant, are sometimes printed on the cloth with the mordant, and the fixation of the color is afterward effected by exposing the cloth to steam. Some coloring matters applied topically in a state of solution become firmly attached to the cloth without a mordant and without the process of steaming, but merely by drying with exposure to the air. 3. For Mineral Colors {Padding Style). — To produce a figure in a mineral coloring material the cloth may oe first printed with one of the two saline solutions, and be afterward uniformly impregnated with the other. To obtain a ground of a mineral color, one or both of the solutions may be applied by the padding machine. 4. Resist Style. — In the processes referable to the resist style, the white cloth is first imprinted with a substance called the resist, or resist paste, which has ihe property of preventing those portions of the cloth on which it is applied from acquiring color when afterward exposed to a dyeing liquid. Resists are divisible into two classes ; one is employed to prevent the attachment of a mordant, and the other that of a coloring matter. 5. Discharge Style.— The object of the processes belonging to this style of work is the production of a white or colored figure on a colored ground. This is effected by applying topically to the cloth already dyed or mordanted, a substance called the discharger, which has -the property of decomposing or dissolving out either the coloring matter or the mordant. Chlorine and chromic acid are the common discharging agents for decomposing a vegetable or animal coloring matter, and an acid solution for dissolving a mordant. 6. For China Blue. — This is a very peculiar style, and is practised with one coloring matter only, namely, indigo. This pigment is printed on the cloth in its insoluble state, and is dissolved and transferred to the interior of the fibre by the successive application of lime and copperas, with exposure to the air. The topical application of the coloring matter, mordant, discharge, or resist, may be made by five different methods : — 1. The simplest is by means of a wooden block, of from nine to twelve inches in length, and from four to seven inches in breadth, bearing the design in relief as an ordinary woodcut ; or, when the design is complicated, and a very distinct impression is required, the figure is sometimes fornaed by the in- sertion of narrow slips of flattened copper wire, the interstices being filled with felt. The block is worked by the hand, and is made of sycamore, holly, or pear-tree wood, on a substratum of some commoner kind of wood. It is charged with color or mordant by pressing it gently on a piece of superfine woollen cloth, called the sieve, which is kept uniformly covered- with the thickened coloring matter or mordant by an attendant boy or girl, called the " tearer," (corrupted from the French word tireur), who %kes the color up by a brush froin a small pot and applies it evenly to the woollen cloth. This cloth is stretched tight over a wooden drum, which floats in a tub full of old paste or thick mucilage to give it sufficient elasticity to allow every part of the raised device on the block to acquire a coating of color. The calico being laid flat on a table covered with a blanket, the charged block is applied to its surface " (the printer being guided where to apply the black by small pins at the cor- ners) and struck gently to transfer the impression. The application of the block to the woollen cloth and the calico alternately is continued until the whole piece of calico is printed. By the ordinary method, a single block prints only a single color ; hence, if the design contain five or more colors, and all be printed by block, five or more blocks will be required, all equal in size with the raised parts in each corresponding with the depressed parts in all the others. If the design, however, requires different colors to be applied in figures in straight and parallel stripes, all the stripes may be applied by one block at a CALICO-PRINTING PEG CESSES. 135 single impression, and the block is also charged with the different colors by a single application to the surface of woollen cloih. The colors to be applied are contained in as many small lin troughs as there are colors, arranged in a line. A little of each color is transferred from the troughs to the woollen cloth by a kind of wire brush consisting of wires fixed in a narrow piece of wood. The color is distributed evenly in stripes over the surface of the sieve, by a wooden roller or rubber covered with fine woollen cloth. For the rainbow style, the colors are blended into one another at their edges bv a brush or rub- ber drawn to and fro in a straight line. An important improvement in the construction of the hand-block has been recently adopted in most Avell-conducted print-works, which consists in the application of a stereotype plate as the printing surface. To make the stereo- type plate, a model is first formed from the pattern, about five or six inches in length, and from an inch and a half to five inches in width, according to the design. A mould is produced by stamping from the model ; and from the mould, fixed in a block, the stereotype copies are produced in a mixed metal, composed of eight parts of bismuth, five parts of lead, and three parts of tin. When a sufficient number of the pieces is prepared, their surlaces are filed down, and they are then fixed to a stout piece of wood. 2. The hand-block has been superseded to a great extent on most parts of the Continent by a machine called the Perrotine, in honor of M. Perrot, of Rouen, its inventor. This machine executes block-printing by mechanical power, and is intermediate in its mode of working between block-printing and cylinder-printing, to be noticed immediately. The perrotine is composed of th ree or four wooden blocks, from two to five inches broad, and as long as the « breadth of the cloth to be printed. The blocks are faced with pear-tree wood and engraved in relief. They are mounted in a cast-iron frame with their planes at right angles to each other, and by a simple contrivance are charged with a coat of colored paste and then pressed successively against tlie cloth- to be printed. The cloth is drawn by a winding cylinder between the engraved blocks and a square prism of iron, mounted so as to revolve on an axis against the blocks. Two or three only of these machines are in operation in this country. 3. About the commencement of the present century the hand-block and flat copper-plate, till then the only means of impression possessed by the printer, began to be superseded, for most styles of work, by cylinders of engraved copper. A general idea of the nature of this mode of printing may be conceived with the assistance of the annexed figure ; a repre- sents the engraved cylinder or roller, mounted on a strong frame-work, so as to revolve against two other cylinders b and c. The cylinder c, which is cover- ed with a woollen cloth, dips into the trough d, con- taining the solution of the coloring matter or mordant properly thickened, and thus acquiring itself a coat- ing of the color, imparts some of it in the act of rotation to the engraved roller a: 5 is a large iron drum or cylinder, the sur- face of which is rendered elastic by several folds of woollen cloth ; around this Fig. 39. \ 136 DYEING AND CALICO-PRINTING. drum travels an endless web of blanket-stuff, e, in the direction of the arrows, accompanied by the calico passing between it and the engraved cylinder. The pressure of the cylinders against each other is regulated by screws or levers, which can be tightened or slackened at pleasure. The excess of coloring matter or mordant which is communicated to the engraved roller by the cylinder c must obviously be removed before it comes into contact with the calico ; this is accomplished by scraping the surface of the roller as it revolves, by a sharp-edged plate, usually of steel, called the color doctor {g). Another similar plate is placed on the opposite side, called the lint doctor, the office of which is to remove the fibres which the roUer ac- quires from the calico. With some color mixtures and mordants, those con- taining salts of copper for instance, doctors composed of gun metal, bronze, brass, and similar alloys, are substituted for those of steel, as the latter would become corroded through the chemical action of the mordant or color mixture. Such is ihe method of printing calicoes by the roller for a single color ; but the mordants or mixtures for two, three, or even eight colors may be applied at the same time by having as many engraved rollers with their appendages revolving simultaneously against the iron drum, as represented in fig. 39, by the dotted cylinders and troughs h, h, i, i. Extreme nicety of arrangement is required to bring all the rollers to print the cloth at the proper places, but when once properly adjusted each may be made to deposite its color or mordant on the calico with the greatest certainty and regularity. The diameter of the printing roller varies from four or six inches to a foot or even more ; its length varies from thirty to forty inches, according to the breadth , of the calico to be printed. It was formerly made of plates of copper hammer- ed into a circular form and joined by brazing ; but as the engraving easily gives way on the brazed joint, the roller is now bored and turned from a solid piece of metal. The engraving is not commonly etched by the ordinary graver, as was formerly done at a great expense, but by the pressure of a steel roller, called the die, from three to four inches in length (according to the pattern), containing the figures in relief which it imparts in intaglio to the softer copper. The steel die is made in a similar manner by powerful pressure against another steel roller called the mill, of similar size, which is engraved by the common graver while in the soft state, and afterward hardened by being heated and then plunged into cold water. The steel die to receive the figure in relief is also in the soft state when pressed against the hardened engraved mill, and is itself hardened before being applied to the copper roller. The cost of engraving a roller in this manner is very little more than one eighth that of engraving by the hand. For some peculiar styles of pattern, the copper roller is etched mstead of being engraved by indentation. The roller being heated by the transmission of steam through its axis, is covered with a thin coat of resist varnish, and when it is cold, the pattern is traced with a diamond point by a very com- plicated and ingenious system of machinery, the roller being slowly revolved at the same time in a horizontal line beneath the tracer. After havmg been etched on its whole surface, the roller is suspended for about five rninutes in a trough containing dilute nitric acid, which dissolves the copper in the lines exposed by the removal of the varnish, but the parts still covered remain un- acted on. The importance and value of this method arises from its affordmg an endless variety of curious configurations, which can hardly be copied or even imitated by the hand engraver. The following ingenious method of imparting a printing surface to a copper roller has been extensively practised of late in one of the best-conducted prmt- works in Lancashire. It is only applicable to rollers to be used for prmtmg a full ground, sprigs or other designs being left blank, for grounding m other colors if required by the block, at a subsequent operation. ' The copper roller is, in the first place, painted with a resist varnish on its whole surface, with the exception of the figures to be left blank ; and to render the blank parts perfectly clean, the roller is dipped, first, into weak nitric acid, and immediately afterward, into clean water. From, the water, the roller CALICO-PRINTING PROCESSES. 137 is transferred to a solution of sulphate of copper and placed in connexion with a galvanic battery, whereby it acquires a coating of copper on the designs where the varnish had not been applied. These raised designs are afterward polished smooth, so that when the roller is in use, they become perfectly cleared by the " doctor," and the ground only is imprinted on the cloth. It will be observed that this method of obtaining a printing surface is essentially different, in principle, from the etching process just described ; in one method, the surface of the roller is covered with varnish on the parts to be raised, and in the other, on the parts to be depressed. 4. A very ingenious method of printing has been lately introduced, distinguish- ed as " press printing," by which block printing with several different colors may be executed at one impression. A sketch of the principal parts of the press-printing machine is shown in fig. 40. The block itself a consists of a well prepared tablet of wood, about two feet six inches square, supported in an iron frame in such a manner that it can be raised or lowered vertically at pleasure. The face of the block is divided into as many stripes (crossways with the table) as there are colors to be printed, which we may suppose, for illustration, to be five. The stripes are about six inches in breadth and as long as the breadth of the cloth to be prmted ; each one prints a different color, and the whole five form together the combined pattern. The printing surfaces are stereotype casts, made of the mixed metal, bismuth, tin, and lead (see page 135). Fig. 40. The mode of applying the colors to the printing surface is very ingenious. At the bottom of the wooden frame h, near to one end of the table, is a felt cushion about the same size as the entire block, and immediately within one side of the frame are arranged in a line five little troughs (or as many as there are colors to be printed), containing the thickened colors. By means of a long 138 DYEING AND CALICO-PRINTING. piece of wood, so formed as to dip into all the troughs at once, the attendant •' tearer" applies a little of each of the five colors to the surface of lelt, over which the colors are evenly spread by a brush in five stripes without any in- termixture. The breadth of the stripes is the same as the breadth of the stereotype rows on the block. The cushion being thus charged, the frame is slid forward on the table on a kind of railway, until it lies immediately underneath the block, which is then lowered by the " pressman" upon the felt cushion, whereby each of the five stripes on the block becomes charged with its proper color. This being done, the block is raised, the color-frame withdrawn, and the block caused to descend on the cloth, which it imprints in five rows with different colors. When the block is raised, the cloth is drawn lengthwise over the table about six mches, or exactly the width of one stripe on the block : the " tearer" again slides over the cushion with more color, and the block is again charged°and applied to the cloth. As a length of the cloth equal to the width of a stripe is drawn from underneath the block at each impression, every part of the cloth is brought into contact successively with all the stripes on the block. The part printed by the fifth stripe at the first impression becomes printed by the fourth stripe at the second impression, by the third stripe at the third impres- sion, by the second stripe at the fourth impression, and by the first stripe at the fifth impression. When this machine is well managed, its action is very neat ; but extreme nicety is required in properly adjusting all the moving parts of the press in order to prevent confusion of the colors and distortion of the pattern. 5. The only mode of printing which remains to be noticed is " surface print- ing," which is merely a modification of roller printing, the cylinder being made of wood instead of copper. The pattern is either cut in relief, as in the ordinary block, or it is formed by the insertion, edgewise, of flattened pieces of copper wire. This cylinder is mounted in a frame as the copper roller, and is sup- plied with color by revolving against the surface of an endless web of woollen cloth, which passes into a trough containing the color or mordant. Surface printing is scarcely at all practised in this country, but in certain styles of work it presents some advantages over copper roller printing, particularly where substances, which corrode copper, but not wood, are to be applied. It is prac- tised more extensively in Ireland than in Lancashire. Thickeners. — The thickening of the' solution of the mordant or the coloring matter in order to prevent the liquid from extending beyond the proper limits of the design, is a subject which requires considerable attention in the success- ful practice of calico-printing. The degree of consistency and the nature of the thickening material require to be varied according to the minuteness of the design and the nature of the substance to be applied, for particular color- ing matters and particular mordants often require particular thickeners. Two simitar solutions of the same mordant, equally thickened, but with difTereni materials, afford different shades of color when dyed in the same infusion and the time required for the fixation of the mordant during the ageing is considerably affected by the nature and consistence of the thickening material with which the mordant had been applied. The following is a list of the thickening materials commouly employed : — 1. Wheat starch. 2. Flour. 3. Gum arable. 4. British gum. 5. Calcined potato starch. 6. Gum Senegal. 7. Gum tragacanth. 8. Salep. 9. Pipe-clay, mixed with either gum arable or gum seaegal. 10. China clay, mixed with gum arable or Senegal. * Solutions of salts of iron or copper thickened with starch give a deeper color to the cloth, whan afterwards dyed, than the same solutions if thickened with gum arabic. CALICO-PRINTING PROCESSES. 139 11. Dextrin. 12. Potato starch. 13. Rice starch. 14. Sago, common and torrefied. 15. Sulphate of lead, mixed with guna arahic or Senegal. The most useful thickeners are wheat starch and flour. When either ot these or any kind of starch (not rpasted) is employed, the mixture with the mordant or coloring matter requires to be boiled over a brisk fire for a few minutes in order to form a mucilage ; the consistency of the mixture, when cold, diminishes if the ebullition is continued for a longer time. Neither flour nor any kind of imroasted starch is well adapted for thickening solutions con- taining a free acid or an acidulous salt ; if other circumstances, however, should render" the introduction of another thickener inadmissible in such a case, the acid or acid salt is always mixed with the thickening after the latter has been boiled and cooled to 120°'or 130^ Fahr. If the acid is boiled with the mucilage, the mixture completely loses its consistency. _ , Starch is almost the only thickener employed for mordants contaming no free acid, and the mordant seems to combine wiih the stuff more readily when thickened wiih starch than when thickened with gum. During the ebullition of starch with red liquor, a precipitate of subsulphate of alumina is produced (see page 115) ; but this precipitate is completely redissolved as the mixture cools, its solution being apparently facilitated by cli 6 st3.rcli» Next to wheat starch and flour, the most generally useful thicKener is gum arable. With this substance, however, many metallic solutions, such as those of salts of tin, iron, and lead, can not be well employed, as such solutions cause the formation of precipitates with an aqueous solution of gum. This objection to the use of gum does not apply to so great an extent to salts of copper. The lime which is contained in all gum arable met with in commerce is apt to affect the light shades of some coloring matters ; but this inconvenience may be overcome by adding to the gum a small quantity of oxalic acid, which converts the lime into the insoluble oxalate. Gum Senegal is used for the same purpose as gum arable. British gum, torrefied or calcined farina, dextrin, and torrefied sago starch (known as " new gum substitute"), are intermediate, both in their properties and applications, between common starch and gum arable. Calcined potato starch is chiefly used with solutions applied by the padding machine, which require very little thickening. Gum tragaeanth and salep are commonly employed as thickeners for solu- tions of salTs of tin and for mixtures containing a considerable quantity of a free acid. Salep does not stiffen and harden the stuffs so much as most other thickeners, and is hence found advantageous for mixing with topical colors. It gives considerable consistence to water, but the mixture is apt to become thin on standing. It is remarkable, that a mixture of solutions of gum tra- gaeanth and gum Senegal, both of the same strength, possesses only one half or one third the consistency of the two solutions before being mixed. Pipe-clay, China clav, or sulphate of lead, when mixed with either gum arable or gum Senegal, is also used with acid mixtures, and with solutions of salts of copper when applied as resists for the indigo vat. The earthy basis acts as a mechanical impediment to the attachment of a coloring matter, when the latter is applied to the whole surface of the cloth. When the mordant to be printed is colorless, or nearly so, as alum red liquor, and salts of tin, it is mixed with a little decoction of logwood, Brazil wood, or some other fugitive dye, in order to render the design on the cloth more perceptible. This addition of color is called s«VA" I«"si°"%l'",-''«S«^---Connexioa l'etwTe°np;rsralLd public improvem^^^^^ mmmmm^ Church.-Grounds for stedlastness in our religious piofcssion.-Elijah the propnet latter days.-Feasiing in captivity—The parting of friends. 4 Valuable Episcopal WorJcs Puhlished by D. Appleton Co. SERMONS PREACHED AT CLAPHAM AND G-LASBURY, BY THE REV. CHARLES BRADLEY, A. M. Two volumes of English edition in one. Price ^1 50- Tlie Sermons of this Divine are much admired for their plain, yet chaste and elegant style ; they will be found admirably adapted for family reading and preaching, where no pastor is located. Recommendations misht he given, if space would admit, from several of our Bishops and Clergy — also from Ministers of various denominations. The following are a few of the English critical opinions of their merit : — "Bradley's Discourses are judicious and practical, scriptural and devout."- iowrwies'* British Lihrarian, "Very ab!e and judicious." — Rev. E. BickerstHh. " Bradley's style is sententious, pithy, and colloquial. He is simple without being quaint : and he almost holds conversation with his hearers, without descending from the dignity of the sacred chair." — Eclectic Review " We earnestly desire that every pulpit in the kingdom may ever be the vehicle of dis" courses as judicious and practical, as scriptural and devout as these." — Christian Observer. HARE'S PAROCHIAL SERMONS. Sermons to a Country Congregation. By Augustus William Hare, A. M., late Fellow of New College, and Rector of Alton Barnes. One vol- ume, royal 8vo. $2 25. " Any one who can be pleased with delicacy of thought expressed in the most simple language— any one who can feel the charm of finding practical duties elucidated and enforced by apt and vaiied illustrations — will be delighted with this volume, which presents us with the workings of a pious and highly-gifted mind." — Quarterly Review. THE CHRISTIAN INSTRUCTED In the Ways of the Gospel and the Church, in a series of Discourses de- livered at St. James' Church, Goshen, New York. By the Rev. J. A. Spencer, A. M., late Rector. One elegant vol. 12mo. $1 00. This is the first volume of Sermons by an American Divine which has appeared for some years. Their style is characterizad by clearness, directness, and force — and they combine, in a happy degree, solid good sense and animation. The great truths of the gospel are pre- sented in a familiar and plain manner, as the church catholic has always held them, and as they are held by the reformed branches in England and America. The Intioduction contains a biief view of the origin, use, and advantages of the various festivals and fasts of the Church ; and to the sermons are appended notes from the writings of Hooker, Barrow, Taylor, Peaison, Chillingworth, Leslie, Horsley, Hobart, and other stand- ard divines, illustrating and enforcing the doctrines contained in them. The book is well adapted to the present distracted state of the public mind, to lead the honest inquirer to a full knowledge of the truth as it is in Jesus, and to give a correct view of the position occupied by the Church. The following is the copy of a letter of recommendation, by the Right Rev. Bishop Onderdonk,of the Diocese of New York : — " Having great confidence in the qualifications of the Rev. Jesse A. Spencer for pastoral instruction in iho Church ofGod, from a personal ncnuaintance with him a.s an alumnus of the General Theological Seminary of the Piotestant Episcopal Church, and as a Deacon and Presbyter of my Diocese, it gives me pleasure to learn, that in his present physical inability to discharge the active duties of the ministry, he purposes publishing a select number of his sermons. Nothing doubting that they will be found instructive and edifying to those who sincerely desire to grow in the knowh^dge and practice of the gospel, I commend them to the pationage of the Diocese ; and this ihe more earnestly, as their publication may be hoped to be a source of temporal comfort and support to a very worthy seivant of the altar, afflicted, at an early period of his ministry, with loss of bodily power to be devoted to its functions." Valuable Episcopal Works Published by D. AppMon Sf- Co. PALMER'S TREATISE ON THE CHURCH. A Treatise on the Church of Christ. Designed chiefly for the use of Students in Theology. By the Rev. William Palmer, M. A., of Wor- cester College, Oxford. Edited with Notes, by the Right Rev. W. K. Whittingham, D. D., Bishop of the Protestant Episcopal Church in the Diocese of Maryland. Two vols. 8vo., handsomely printed on fine pa- per. $5 00. " The treatise of Mr. Palmer is the best exposition and vindication of Church Principles that we have ever read: excelling contemporaneous treatises in depth of learnmg andsohd- itv of iudr^ment, as much as it excels older treatises on the like subjects, in adaptation to the wants'and habits of the age. Of its influence in England, where it has passed through two editions, we have not the means to form an opinion ; but we believe that m this coun- try it has already, even before ils reprint, done more to restore the sound tone ol Oatholic principles and feeling than any other one work of the age. The author's learning, and powers of combination and arrangement, great as they obviously are, are less remarkable than the sterling good sense, the vigorous and solid judgment, which is eveiywhere manifest in the treatise, and confers on it its distinctive excellence. The style of the author is distinguished for dignity and masculine energy, while his tone is everywhere nat- ural ; on proper occasions, reverential ; and always, so far as we remember, sufficiently con- '^'''u'Toour clergy and intelligent laity who desire to see the Church justly discriminated from Romanists on the one hand, and dissenting denominations on the other, we earnestly commend Palmer's Treatise on the Church."— JV. Y. Churchman. "This able, elaborate, and learned vindication of the claim of the Protestant Episcopal Church, to be considered the true Catholic Church, and the exposure which is here made ot theg'ounds of difference between itand the Romish Church, and of the baseless pretensions of that Church to be the ' one Holy Catholic, and Apostolic Church,' will assuredly commeud these volumes to the favor of Churchmen." — JV. Y.American. ECCLESIASTES ANGLICANUS; BEING A TREATISE ON PREACHING In a Series of Letters by the Ret. W. Gresley, M. A. Revised, with Supplementary Notes, by the Rev. Benjamin I. Haight, M. A., Rector of All Saints' Church, New York. In one handsomely printed volume, 12mo. Price $] 25. Mvertisement.—ln preparing the American edition of Mr. Gresley's valuable Treatise, a few foot notes have been added by the editor, which are distinguished by brackets. Ihe more extended notes at the end have been selected from the best works on the^subject— and which, with one or two exceptions, are not easily accessible to the American Student. HEADS OF CONTENTS. Letter 1. Introductory. Part!. On the matter of a Sermon. Letter II. The end or object of Preaching. III. The principal topics of the Preacher. IV. and V. How to sain the Confidence of the hearers-First, By showing goodness of character. VI. Secondly, By showing a friendly disposition towards them VIL Thirdly, By showing ability to instruct them. VIII. On Arguments-those derivable from Scripture. IX. On Aiguments. X. On Illustration. XI. How to move the passions or 'eelings-lirst, By indirect means. XII. Secondly, By direct means. Part If. %^^^l'''^-^,fl^l:JiJ}^f^y\l -general remaiks. XIV. Perspicuity, Foice, and Elegance. XV. to XVIIL On btyle, as cussion-Lectures. XXVI. On Discussion-Text-Sermons. XXVII. On Discussiori- Subject-Sermons, XXVIIL On Application. XXIX On the Conclusion. Part IV. On Delivery. XXX. Management of the Voice. XXXI. Earnestness and Feeling. XXXU. Gesture and Expression. XXXIII. Extemporaneous Preaching. SuppLEMENTARy Notes. A.— Matter of Pleaching. B.— Sermons to be plain. C— Texts. D.— Unity. E.— Exposi- tory Preaching. F. — Written and Extemporary Sermons. 6 Valuable Episcopal Works Published by D. Appleton Sf Co THE KINGDOM OF CHRIST; OR Bints Respecting the Principles, Constitution, and Ordinancetj OF THE CATHOLIC CHURCH. BY FREDERICK DENISON MAURICE, M. A., Chaplain of Ouy's Hospital, Professor of English Literature and History. Kings's College, London. In one elegant octavo volume of 600 pages, uniform in style with JVcwman^s Ser- mons, Palmer on the Church, ^c. $2 50, The following brief table of contents illustrates the more important topics treated on in this very able work. Part I. On the Principles of the Quakers, and of the different religious bodies which have arisen since the Reformation, and of the systems to which they have given birth. Chapter I. — QUAKERISM. On the positive doctrines of the Quakers — ordinaiy objections to these Doctrines. The Quaker System — Practical Woikings of the Quaker System. Chapter II.— PURE PROTESTANTISM. The leading Principles of the Reformation— Objections to the Principles of the Reformation Considered — Protestant Systems — The Practical Work- ings of the Protestant Systems. Chapter JII.— UNFTARIANISM— its History and Ob- ject lUustiated. Chapter IV. — On tlie Tendency of the Religious, Philosophical, AND Political Movements which have taken place in Protestant Bodies since THE MIDDLE of THE LAST Centurv. The RcHgious Movements, Philosophical Move- ments, Political Movements. Part II. Of the Catholic Church and the Romish System. Chapter I — Recapitulation Chapter II. — Indications of a Spiritual Constitution. Chapter III. — The Scrip- tural view of this Constitution. Chapter IV. — Signs of a Spiritual Society — Baptism — The Creeds — Forms of Worship — The Eucharist— The Ministry — the Scriptuies. Chapter V. — Of the Relation of the Church and National Bodies— Introductory— Objections of the Quakers — The Pure Theocratist — The Separatist — The Patrician — The Modern Statesman — The Modern Interpreter of Prophecy. Part III. The English Church and the Systems which Divide tt. Chapter I. — Intro- ductory — How far this Subject is connected with those previously Discussed. Do the Signs of a Universal and Spiritual Constitution exist in England Does the Universal Church in England exist apart from its Civil Institutions in Union with them } What is the form of Character which belongs especially to Englishmen To what depravation is it liable Chapter 11.— The English Systems. The Liberal System — The Evangelical System — The High Church or Catholic System. Reflections on the Systems, and on our position generally. Mr. Maurice's work is eminently fitted to engage the attention and meet the wants of all interested in the several movements that are now taking place in the religious community ; it takes up the pretensions generally of the several Protestant denominations and of the Ro- manists, so as to commend itself in the growing interest in the controversy between the lat- ter and their opponents. The political portion of tlie work contains much that is attractive to a thouglitful inan, of any or of no religious persuasion, in reference to the existing and possible future state of our country. " On the theory of the Church of Christ, all should consult the work of Mr. Maurice, the most philosophical writer of the day." — Professor Oarbett's Bampton Lectures, 1842. PEARSON ON THE CREED. An Exposition of the Creed, by John Pearson, D. D., late Bishop of Ches- ter. With an Appendix, containing the principal Greek and Latin Creeds. Revised and corrected by the Rev. W. S. Dobson, M. A., Pe- terhouse, Cambridge. In one handsome 8vo. volume. $2 00. The following may be stated as the advantages of this edition over all others. First — Great care has been taken to correct the numerous eriors in the references to the texts of Scripture which had crept in by reason of the repeated editions through which this admirable work has passed ; and many references, as will be seen on turning to the Index of Texts, have been added. Secondly — Tlie Quotations in the Notes have been almost universally identified and the refeience to them adjoined. Lastly— The principal Symbola or Creeds, of which the particular Articles have been cited by the Author, have been annexed ; and wherever the original writers have given the Symbola in a scattered and disjointed manner, the detached parts have been brought into a successive and connected point of view. These have been added in Chronological order in the foim of an Appendix. — yide Editor. Valuable Episcopal Works Published by D. Appleton 4* Cb- CHURCHMAN'S LIBRARY. The volumes of this Standard Series are highly recommended by the Bishops and Clergy of the Protestant Episcopal Church. The Publishers beg to state, while in so short a time this Library has incieased to so many volumes, they are encouraged to make yet larger addi- tions, and earnestly hope it may receive all the encouragement it deserves. The following works have already appeared : — THE UNITY OF THE CHURCH. BY THE REV. HENRY EDWARD MANNING, M. A., Archdeacon of Chichester. Complete in one elegant volume, 16mo. Price $1 00. CONTENTS. Part I. The Histokt and Exposition of the Doctrine of C.itholic Unity. Chap. I. The Antiquity of the Article, "I believe in the Holy Church." II. Inter- pretation of the Article, "The Holy Church," as taught by uninspired writers . Ill 1 he Unity of the Church ks taught in Holy Scripture. IV. The Form and Matter of Unity. %tt"lT THE^MolrDESioN or C.T„or.ic Unitv. Chap I. The Moral Design of the Church as shown by Holy Scripture. II. The Unity of the Church a means to restore the tru^ Knowledge of GoZ III The Unity of the Church a Me'ins to restore Man to ^^^^^ Image of Godf IV. The Unity of the Church a Probation of the Faith and Will of Man. Conclusion to the second part. , a Part III. The Doctkinf. of Catholic Unity applied to the Actual State Christendom. Chap. I. The Unity of the Church the only Revealed way of Salvation.. II The Loss of Objective Unity. III. The Loss of Subjective Unity. General Conclusion " This is a profound and eloquent treatise on a most interesting sutjject-one t|'^t '^as of late received peculiar attention, and at p.esent exeic.ses the minds "'^f'^'f"' Christians perhaps more than any other. Thousands are beginning to be convinced that the only tr ue and real bond of concord is the kingdom of Christ, and to inquiie anxiously into the mean- fng of that article of the Creed-" I believe one Catholic and Apostolic Church." A 1 such wfll read with avidity the admirable treatise which has been so favouiably received in England, and whose republication in such beautifu sty e entitles Messrs. Appleton to the Ss of American Churclimen. Archdeacon Manning is well known by otiier theological works: but his Unity of the Church is the most matured and celebrated production of bis pen, and it has placed him high in the rank of Anglican divines.'>-Ban«cr of the Cross. THE DOUBLE WITNESS OF THE CHURCH. By the Rev. Wm. Ingraham Kip, author of "Lenten Fast." One ele- gant volume, 16mo., of 415 pages. Price $1 25. me^°n^l^^^p.^^prd^Lnf^SL!^^^^^^^ feSs to the altfrch. IX. The Church in all ages the Keeper of the 1 ruth. X. Con- clusion. The Catholic Churchman. „ , j " This is a sound clear, and able production -a book much wanted for these times, and — Christian Witness and Mvocatc. Q Valuable Episcopal Works Published by D. Appleton Co. CHURCHMAN'S LIBRARY.— Oontiiiued. 3rf)e eijurcSman's Companion tn tlje (Srioset : OR, A COMPLETE MANUAL OF PRIVATE DEVOTIONS: Collected from the writings of Archbishop Laud, Bishop Andrews, Bishop Ken, Dr. Hickes, Mr. Kettlewell, Mr. Spinckes, and other eminent OLD English divines. With a Preface by the Rev. Mr. Spinckes. Editedby Francis E. Paget, M. A. One elegant volume, 16mo. $100 _ The pious reader will require no more recommendation of this volume than that which he will find in its title-paije. A Manual of Prayers compiled from the devotional writings of Laud and Andrews, Ken and Hickes, Kettlewell and Spinckes, cannot be otherwise than acceptable to all who love those principles which they unanimously taught, and for the maintaining ol which, (with the exception of the good Bishop of Winter, whose lot was cast in tranquil times,) they suftered according to the measure which God required of each ; to all who would fiiin follow them in the paths of self-denial, spiritual-mindedness, meekness, and obedience. And that this book has been to past generations what it is hoped it may like- wise be to our own, is evident from the flict that it is one of the few of the devotional works of the seventeenth century, which continued to be in constant demand during the eighteenth. Its value was appreciated, and it continued to be reprinted from time to time to the middle of the last century ; and it is presented to the public once more, with the anxious desire that as it found ftivour to the last, while Church principles were declining, so it may prove acceptable to the many, who (blessed be God) seem now to be zealously arid faithfully seek- ing their way back to the " old paths" from which we have v/&aIAW'S LIBRAEY.— Continued. THE RECTORY OF VALEHEAD: OR THE RECORDS OF A HOLY HOME. BY THE EEV. R. W. EVANS. From the Twelfth English edition. One elegantly printed volume, 16mo. 75 cents. " Universally and cordially do we rncommcnd this delightful volume. We believe no person could read this work and not be the better for its pious and touching lessons. It is a page taken from the book of life, and eloquent with all the instruction of an excellent pat- tern ; it is a commentary on the affectionate warning, ' Remember thy Creator in the days of thy youth.' We have not for some time seen a work we could so deservedly praise, or so conscientiously recommend." — Literary Oaictlc. "This work illustrates with great simplicity and beauty and variety, the privileges, bless- ings, and influences of the Christian home. It is ricli in elegant de.-icription, in fine moral sentiment, and withal is happily imbued with tlie spirit of genuine Chiistianity. In wish- ing it an extensive circulation, we are sure that we are only wishing well to the cause of domestic piety and order and happiness. — Albany Advertiser, PORTRAIT OF A CHURCHMAN. BY THE REV. W. GRESLEY, A. M From the Seventh English edition. One elegant volume, 16mo. 75ceqts. " The present volume is an attempt to paint the feelings, habits of thought, and mode of action which naturally flow from a .sincere attachment to the system of belief and discipline adopted in our Church. " Church princ pies have been so much discussed of late, that I would have willingly passed over that part of the subject ; but daily experience proves that they are still very inipeifectly understood, or little con.^idered, by the mass of those who call themselves Churchmen. I have therefore devoted some chapters in the earlier part of the work to a brief, though not careless or hasty, discussion of the principles of the Church of Christ. But the main pait of the volume isoecui)ied upon the illustration of the practical working of those ■principles when sincerely received^ setting forth their value in the commerce of daily life, and how surely they conduct those who embrace them in the safe and quiet path of holy life." — AutJwr^s Preface. LYRA APOSTOLICA. From the Fifth English edition One elegantly printed volume 75 cents. " Here is a volume of poetry on grave subjects ; where the taste, the sensibilities, and the judgment, all are interested. Some of its topics are purely imaginative, but the large majority are on matteis to which every thoughtful mind often recurs ; and by the consider- ation of which the heart and conscience are benefited. In this elegant volume, there are forty-five sections, and one hundred and eevenly-nine Lyric poems, all short, and many of them sweet." — JV. Y.American' " This is a collection of Lyrical Odes, which originally were published in the British Ma- gazine ; and were subsiKjuently combined in a handsome volume. They are all upon grave topics, and arranged under forty-five different heads ; and their poetical merits are common- Burate with the serious dignity of the subjects. It cannot be e.'ipected that one hundred and se- venty-nine different poems, written by an association of authors, can beequ'iliind uniform in poetic ability— nevertheless, they all exhibit a high degree of merit. Some of the Odes are of a very superior order, and contain such pithy instruction that the work is just fit for the pock- et of every lovei of Christian Song, on account of the brevity of almost all the articles Johnson once stated that there could not possibly be any good poetry on sacred subjects. If the volumes of Milton, and Young, and Cowper, and Montgomery, had n'^t shown the error of his decision, the Lyra Apostolica would prove that his opinion was contrary to fact. The beauty of the work accords with its melodious chants." — JV, Y. Courier and Enquirer. Valuable Episcopal Works Published by D. Appleton ^ Co. CHURCHMAN'S LIBRARY.— Continued. BISHOP JEREMY TAYLOR ON EPISCOPACY. The Sacred Order and Offices of Episcopacy asserted and maintained ; to whicli is added, Clerus Domini : a Discourse on tlie Office Ministeri- al ; by the Right Rev. Bishop Jeremy Taylor, D. D. One elegant vol- ume, 16mo. Price $1 00. 9:5' The reprini m a portable form of this Eminent Divine's masterly Defence of Episco- pacy cannot fail of being welcomed by every Churchman. 'With the imagination of a Poet, and the fervor of an Apostle, JeremjiTaylor cannot be republished in any shape that he will not have readers. More especially, just now will this treatise of his be read, when, by feebler hands and far less well furnislied minds, attempts are making to depreciate that sacred order and those sacred offices which are here with tri- umphant eloquence maintained. " The i)ublisherB have presented this jewel in a fitting casket." — JV. Y. American, Feb. 17, ]844. " Jeremy Taylor was not simply an ornament to the English Church, hut in his Christian walk and conversation an example to Christians of all denominations. His style has in it all the elements of eloquence, earnestness of purpose, comprehensiveness of tliought, and de- votional fervor. The work under notice is particularly adapted to the study of such Ep s- copalians as would understand the grounds of their recognized orders. — U. S. Saturday Post. " On the merit of Bishop Taylor it would be absurd and useless to expatiate. His piety has been the subject and admiration, and his eloquence the theme of praise, to our best writ- ers. " — British Critic. THE GOLDEN GROVE: A choice Manual, containing what is to be believed, practised, and de- sired, or prayed for; the prayers being fitted for the several days of the week. To which is added, a Guide for the Penitent, or a Model drawn up for the help of devout souls wounded with sin. Also, Festival Hymns, &c. By the Right Rev. Bishop Jeremy Taylor. One vol. Ibmo. $0 50. " The name of Jeremy Taylor will always be a sufficient passport to any work on whose title page it appears. Of no writer of his period, or indeed of any other period, could it be more truly said, that he has given ' thoughts that breathe in words that burn.' The present little work may perhaps be regarded as among the choicest of his productions. While it is designed to be a guide to devotion, it breathes much of the spirit of devotion, and abounds in lessons of deep practical wisdom. Its author was an Episcopalian, and Episcopalians may well be proud of him ; but his character and writings can no more be the property of one de- nomination than the air or the light, or any other of God's universal blessings, to the world." — Albany Advertiser. SACRA PRIVATA. The Private Meditations, Devotions, and Prayers of the Right Rev. T. Wilson, D. D., Lord Bishop of Soder and Man. First complete edi- tion. One vol. royal 16mo., elegantly ornamented. $1 00. "The Messis. Appleton have brought out, in elegant style, Wilson's ' Sacra Privata ' entire, The reprint is an honour to the American press. The work itself is, perhaps, on the whole, the best devotional treatise in the language, and it now appears in a dress worthy of its character. It has never before in this country been printed entire. We shall say more anothei time, but for the present will only urge upon every reader, from motives of duty and interest, foi private benefit and public good, to bay the book. Buy good books, shun the doubt- ful, and burn the bad." — The Churchman. A neat Miniature Edition, abridged for popular use, is also published. Price 31 1-4 cents. 12 Valuable Episcopal Worlcs Puhtislied hy D. Appleton Co, OHUROHMAN'S LIBRARY— Continued. THE EARLY ENGLISH CHURCH; Or, Christian History of England in early British, Saxon, and Norman Times. By the Rev. Edward Churton, M. A. With a Preface, by the Right Rev. Bishop Ives. One vol. 16mo. elegantly ornamented. $1 00. " The following delightful pages place before ii3 some of the choiceat exaniples — both clerical and lay— of the true Christian spirit in the EARLY ENGLISH CHtTUCH. In tiuth, these pages are crowded with weighty lessons. Heie our laity will find that these no- ble foundations of charity in the mother country— 'the existonce of which they have been accustomed to ascribe to the credulity of ignorance, oi the fears of superstition, successfully practised upon by tlie arts of priests, had a higher and liolier origin — that they sprung into being under the warm impulses of that divine and expansive benevolence of which the cori' straining power of Christ's love made his early followers such large partakers at the period while yet Christian men fully recognized their high vocations, as ' stewards of the manifold gifts of God,'— lived under the abiding conviction, that we are not our own, but that, ' bouf ht with the precious blood of Christ,' we are ' bound to glorify him in our bodies and our spirits which are his.' Here, too, our clergy may learn a lesson of true self devotion to their Master— may see, strikingly and beautifully illustrated, that love for Christ, and that zeal for his kingdom, which alone can bear us tranquilly and successfully through the la- bours and trials of the holy ministry— may see the operation of the true missionary spirit— the spirit of endurance and self-sacrifice, which shrinks from no obstacles wlien the salva- tion of sinners is to be achieved under the command and the promise of the Almighty God — ' may see, in short, an impressive and instructive exemplification of that child-like submission to God, that pure and simple trust in him, which, at his bidding, performs duty, and leaves the result to his providence and grace. "But, to read these pages with profit, we must pray to God for a portion of that spirit which indited them, and which so manifestly control the events which they record — must read them with a spiritual eye ; with an eye intent upon discovering, not that wliich may help to sustain some preconceived notion, but that which, prompted by the spirit of Christ, and accomplished through the power of his saving truth, exhibits to us some great principle of Christian action, and some powerful motive to go and do likewise." — yide Preface. TALES CF THE VILLAGE; In which the Principles of the Romanist, Churchman, Dissenter, and In- fidel are contrasted. By the Rev. Francis E. Paget, M. A. In three elegant vols. 18mo. $1 75. " These three handsome little volumes constitute series of Tales, purporting to be the record kept by a country clergyman, of scenes passing under his own view, in the discharge of his parochial duties. They have had great success in England, as, we doubt not, this first American edition of them will have here. " They are well contrived : s tales to interest the reader, and skilfully tised as vehicles for setting forth the sound doctrines of the Church, which, while ' protesting against Rome, remains Catholic, and while protesting against Geneva, is Reformed j whose hand is against all error, and all error against it.' " The first series or volume, presents a popular view of the contrast in opinions and modes of thought between Churchmen and Romanists ; the second sets forth Church princi- ples, as opposed to what, in England, is termed Dissent ; and the third places in contrast the character of the Churchman and the Infidel. " At any time these volumes would be valuable, especially to the young. At present, when men's minds are much turned to such subjects, they cannot fail of being eagerly sought for." — JVeW'Ynrk American. " The first, second, and third series, in as many small volumes, of these popular tales, are now oifered to tlie American public. At present, we have only room to commend them, and we do it most heartily, to all who desire edification combined with amusement." — The Churchman. THE CHRISTMAS BELLS; A Tale of Holy Tide, and other Poems. By the Rev. J. W. Brown, au- thor of " Constance," "Virginia," &c. One vol. royal l6mo., elegantly ornamented. $0 75. " Many of the smaller pieces in this volume have appeared from time to time in various journals and magazines, and have been received with unqualified favour. The lea.ing poem was written for the most pait during the season whose enjoyments and happy ind ences it is designed to commemorate. The plan of it was suggested by the perusal of Washington Irving's delightful Essays on the Christmas season, in the Sketch Book." — Preface. Valuable Episcopal Works Publishe d hy D. Apphton Sf C o. A MANUAL FOR COMMUNICANTS; Or, the Order for Administering the Holy Communion ; conveniently arranged with Meditations and Prayers from Old English Divines, being the Eucharistica of Samuel Wilberforce, M. A., Archdeacon of Surry, (adapted to the Am-srican service.) Convenient size for the pocket. cents ; gilt leaves, 50 cents. " The order of this work is as follows :— First, " The Exhortation ;" comprising the two exhortations which are inserted in the Communion Office ; then the " Ante-Communion ;" next " The Canon of the Holy Communion," beginning with the Offertory and ending with the Form of administering the elements ; and lastly, the Post-Communion. This part of the work is the Communion Office as contained in the Prayer Book, slightly altered in its arrangement, and accompanied with a few short devotional meditations in the margin. After this is the Introduction by Archdeacon Wilberfoice, chiefly on the impcnance of attendance at the Lord's Tabb, and the causes of the present neglect of the privilege. " We have next a brief notice of the writers from whose works are taken the extracts which form the body of the volume. These arc Colet, Cranmer, Jewel, Hooker, Andrews, Sutton Laud, Hall, Hammond, Taylor, Leighton, Brevint, Patrick, Addison, Ken, Sparrow, Beverid^e, Hicks, Comber, Kettlewell, Wilson, and Potter; whose names are arranged in chronolo"ical order, with a mention in lew lines of their lives and characters. The remainder of the work is divided into three parts ; of which the first consi>ts of Meditations on the Holy Communion ; the second of Prayers before and after Communion ; to which are added. Bishop Wilson's Meditations on Select Passages, and Bishop Patrick's Prayer for one who cannot publicly communicate; and the third of select passages explanatory of the Holy Sacramentand the benefits of its worthy reception. _ , , , .,1 " These meditations, prayers, and expositions, are given in the very words of the illos- trious divines above mentioned, raaityis, confessors, and doctors of the Church; and they form altogether such a body of instructive matter as is nowhere else to be found in the same compass. Though collected from various authors, the whole is pervaded by a unity of spirit and purpose ; and we most earnestly commend the work as better fitted than any other which we know, to subserve the ends of sound edification and fervent and substantial devo- tion. The American reprint has been edited by a deacon of great promise in the Church, and is appropriately dedicated to the Bishop of this diocv.se."— Churchman. THE PRIMITIVE DOCTRINE OF ELECTION: Or, an Historical Inquiry into the Ideality and Causation of Scriptural Election, as received and maintained in the primitive Church of Christ. By George Stanley Faber, B. D., author of "Difficulties of Roman- ism," "Difficulties of Infidelity," «&c. Complete in one volume, octavo. $1 75. " Mr Faber verifies his opinion by demonstration. We cannot pay a higher respect to his work than by recommending it to nW."— Church of England Quarterly Review. LETTERS TO MY GODCHILD. BY THE REV. I. SWART, A. M. One elegant miniature volume. Price 37 1-2 cents. " The design of this little work — dedicated by permission to Bishop Onderdonk, and commended by Bishop Delancey, to whom while in preparation the MS. was submitted— is to enable those whom distance or other circumstances prevent from adequately discharging their sponsorial duties, to place in the hands of their godchildren a treatise which saall elucidate the relations between the sponsor and his godchild, and supply, as far as may be, the want of immediate and constant personal supervision. c „ "The commendation of this Diocesan is an all-sufficient introduction of Mr. Swart's ose- ful little book."— JV. Y.American. OGILBY ON LAY BAPTISM. An Outline on the Argument against the validity of Lay-Baptism. By the Rev. John D. Ogilby, D. D., Professor of Ecclesiastical History. One volume, 12mo. $0 75. » We have been favoured with a copy of the above work. 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He is an excellent scholar, an acute reasoner, and is possessed of a most extensive acquaiiitance with the wide field of argument to which hia volumes are devo ed — the profound Biblical information on a variety of topics which the Archbishop brings forward, must cndeai bis name to all lovers of Christianity." — Orme. Tx?ittu on (t\)xintimx Boctrtne antr |3racttce. Under tliis general head it is proposed to publish a series of Catechetical Works, illustrating the Doctrine, Di-cipline, and Pii.ctice of the Protest- ant Episcopal Church in the United States. The fjllowingcommence the Series : ■' A HELP TO CATECHISING; FOR THE USE OF CLERGYMEN, SCHOOLS, AND PRIVATE FAMILIES. BY JAMES BEAVEN, D. D. Professor of Theology at King's College, Toronto. Revised and adapted to the use of the Protestant Episcopal Church in the United States. BY HENRY ANTHON, D. D. Rector of St. Mark's Church, New- York. Price— single copies, 6 1-4 cents — 50 copies, f 2 50 — 100 copies, $4 00. Numerous testimonies have been received of the usefulness of this Catechism, and the very moderate price affixed leads the publishers to hope for it a very extensive circulation. Its sale has already exceeded 12,000 copies. CATECHISMS ON THE HOM ILIES OF THE CHURCH. I. On the Miseries of Mankind. II. Of the Nativity of Christ. III. Of the Passion of Christ. IV. Of the Resurrection of Christ. BY HENRY ANTHON, D. D. Price— single copies, 6 1-4 cents — 50 copies, $2 50—100 copies, $4 00. The object of these Catechisms is to present the Homilies in a shape in which they cao be learned, marked, and digested, by the youthful members of the Church. 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