APPLIED CHEMISTRX; MANUFACTURES, ARTS, AND DOMESTIC ECONOMY. iDITED BY EDWARD ANDREW PARNELL, AUTHOR OF " ELEMENTS OF CHEMICAL ANALYSIS," LATE ASSISTANT CHEMICAL LECTURER IN THE MEDICAL SCHOOL OF ST. THOMAS'S HOSPITAL, ETC. PRELIMINARY OBSERVATIONS. GAS ILLUMINATION. PRESERVATION OP WOOD. DYEING AND CALICO-PRINTING. LONDON: PRINTED FOR TAYLOR AND WALTON, UPPER GOWER STREET. 1844. London ; Printed \iy S. & J. Bentley, Wilson, and Fley, Bangor House, Shoe Lane. THE J. PAUL GETTY CENTER LIBF^Y PREFACE. The " Preliminary Observations," with which this volume commences, comprise some brief considera- tions on the fundamental doctrines of chemistry, motst 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 pro- perties of the constituents of coal-gas, but several important collateral subjects; among which are some considerations on the modes of burning gas and on the economy of gas illumination, descriptions of the processes 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 regulators and meters, and the process of " naph- thalizing" gas, are also considered. In the article on the Preservation of Wood, which follows that on Gas Illumination, means are pointed out for effectually guarding against the ordinary de- vi PREFACE. composing influences of air and water on timber. A considerable portion of the article is devoted to an account of the important experiments of Mr, W. Hyett, on the effects of the impregnation of wood with foreign substances. Dyeing and Calico-printing forms the comprehen- sive subject of the concluding article of the present volume. Most of the leading processes now practised by the calico-printers of this country are there de- scribed, accompanied with explanations of the scien- tific principles on which they are based. Sereral of these processes, new to treatises on the subject, will be found of considerable value. 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 Blackburn, to whom I feel myself bound to return my sincere 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 Wlialley, TABLE OF CONTENTS. PAGE Preliminary Observations ..... 1 Attainments of the ancients in some chemical arts. — Probably ac- quired 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 process of Hernando Velasquez ..... 1 Chemical affinity ...... 7 Elements,— Difference between a chemical compound and a me- chanical compound ...... 8 Chemical affinity exerted with different degrees of force between different substances ..... 10 Chemical union of substances takes place in fixed and definite pro- portions. — The same element combines with different quantities of different substances. — Table of chemical equivalents of elements. — Bodies always imite chemically in the proportion of their equi- valents ....... 13 Heat developed through chemical combination . . 20 Chemical combination may be direct or indirect. — Double decompo- sition and double combination. — Single decomposition and single substitution ....... 21 Solution. — Crystallization ..... 24 Proximate and ultimate constituents . . . .27 Symbols . . • • . • . 30 Table of equivalents of acids and bases . . . .34 I. GAS ILLUMINATION. Outline of the process of making light-gas ... 35 § I. Historical sketch of the progress of Gas illumination 37 § II. Composition of Coal . . . . 47 General composition. — Ultimate composition. — Atomic constitution of splint and cannel coal. — Extraneous matters . . 47 Vlll CONTENTS. PAGB § III. Hydrocarbons ..... 52 Illuminating power of coal-gas due to hydrocarbons. — Isomerism 52 Light carburetted hydrogen. — Its composition and properties 54 Olefiant gas. — Mode of preparation. — Its properties and composi- tion. — Fire-damp. — Safety-lamp . . . .56 Naphthalin and paranaphthalin. — Coal-oil ... 59 § IV. Process of making Coal-gas . . .62 Coal-gas apparatus ...... 63 Figure exhibiting the arrangements of a gas-work . . 64 Table of the products of the destructive distillation of coal . 65 Retort. — Mouth-piece. — Hydraulic main . . .66 Gas carbon. — Method of removing it . . . 69 Tar cistern. — Cooler or condenser. — Coolers of Mr. Perks and Mr. Malam ........ 70 Lime purifier. — Wet-lime and dry-lime purifiers . . 72 Gasometer. — Telescope gasometer . ^ . .76 Coal affords different products at different stages of the distillation. — Composition of coal-gas in one hundred volumes . 80 Rules for producing good coal-gas. — Rotary retort. — Temperature of retort should not be above bright redness. — Advantage of se- lecting a rich coal. — Advantage of using coal with a minimum of sulphur, and previously dried . . . . .81 Ammonia formerly contained in purified coal-gas. — Process of Mr. Phillips of Exeter for removing the ammonia. — Use of copperas, dilute sulphuric acid, chloride of calcium, sulphate of manganese, and sulphate of lead, for removing the ammonia . . 88 § V. Secondary products of the Coal-gas manufacture . 92 Ammoniacal liquor ...... 92 Coal-tar. — Coal-oil. — Coal-naphtha. — Pitch . . .94 Coke. — Composition and properties of coke. — Uses in metallurgic works, «&c. 96 § VI. OiL-oiis 97 Kind of oil used. — Process.— Apparatus. — Composition of oil-gas. — Liquids obtained by the compression of oil-gas. — Benzin. — Oil-gas too expensive to be adopted in this country . 97 § VII. Resin-gas . . . . . ,101 Resin-gas not adapted for this country.— Apparatus for making resin-gas. — Application of the volatile oil disengaged from the resin. — Product of gas. — Illuminating power of resin-gas . 101 Turf-gas . . . . . . .104 CONTENTS. ix PAGE § VIII. MODB OF BURNING GaS .... 104 Ignition. — Structure of an ordinary flame. — Luminous flame always comtains solid matter heated to whiteness. — Luminosity of a flame depends on the consecutive combustion of the hydrogen and carbon. — Different kinds of gas-burners. — Cockspur. — Union jet or fan. — Bat-wing. — Fish-tail or swallow-tail. — Argand. — Bude ligM. — Solar gas-lamp . . . . .104 A given quantity of gas gives more light in one flame than in several flames . . . . . . 113 Influence of the shape of the chimney on the amount of light . 113 Disadvantages of too free a supply of air . . . 114 Arrangement for burning gas as a source of heat in the laboratory 115 Vent ilation of gas-lights . . . . . 117 § IX. Economy of Gas illumination . . . 121 Expenses of the manufacture and the value of the products in Lomdon ....... 121 Light from gas compared with that from other sources . 122 Table shewing the relative value of coal-gas made at different works ........ 125 Relative economy of coal-gas and oil-gas . ^ . 126 § X. Estimation of the value of Light-gas . . 126 Photometrical processes of Lambert, Dr. Ritchie, and M. Arago 127 Illuaiinating power of light-gas related to the density . . 130 Illuminating power related to the quantity of oxygen required for the perfect combustion of the gas .... 131 Eudiometrical process ...... 132 Process for the complete analysis of coal-gas . . 136 Simple process for estimating the value of light-gas by means of chlorine ....... 137 § XI. Regulators and Meters .... 138 Water and mercurial regulators. — Constant pressure regulator. — Platow's gas moderator ..... 138 Common water meter. — Edge's " improved gas meter " (Note). — Clegg's " dry gas meter." — Lowe's meter. — Station meter 141 Naphthalized gas . . . . . .145 Apparatus used for " naphthalizing " gas. —Economical advantages of naphthalized gas ..... 145 Attempt to convert tar into gas ..... 148 X CONTENTS. II. PRESERVATION OF WOOD. PAGE Rot and decay of wood are chemical changes. — Two conditions in which decay of wood can take^' place. — Nature of dry-rot . 151 § I. Properties and composition of Wood . . 153 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. — Alburnum or sap-wood. — Origin of of woody tissue. — Endogens .... 153 Seasoning of wood ...... 159 Density of different kinds of wood .... 162 Soluble matters in wood. — Vegetable albumen. — Starch . . 164 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 dis- tillation of wood. — Flame of burning wood. — Wood smoke. — Heating power of different kinds of wood in a state of combus- tion. — Composition of wood ashes . . . 165 § II. Nature and causes of the decay of Wood . 175 Decay of woody fibre a process of oxidation. — Eremecausis . 175 Decay of wood always produced by the contact of another body un- dergoing a similar change . . . . . 181 Decay of wood closely analogous to acetification . . 181 Albuminous matter in wood acts as a ferment . . .182 Processes for ascertaining the proportion of albuminous matter in wood . . . . . . . 183 § III. Preservative materials .... 184 Decay of wood may be prevented by removing the albumen or by preventing its decomposition . . . . 184 Removal of the albumen by water . . . .185 Corrosive sublimate . . . . . . 185 Action of corrosive sublimate confined to the albumen . .186 Process for applying corrosive sublimate . . . 187 Protection of wood by the application of a varnish . . 187 List of preservative materials . . . . 188 Sulphate of copper ; sulphate of iron and sulphate of zinc . 189 Alkalies and alkaline earths . . . . . 189 Alum ........ 190 Common salt ...... 190 Vegetable and animal oils . . . . .191 CONTENTS. xi PAGE Vapour from fixed oils ..... 192 Arsenious acid. — Mundic water ..... 192 Tannin, — Durability of wood imbedded in bogs . , 193 Creosote ....... 193 Tar ....... 193 Oil of wood-tar . . . . . . .194 Peroxide of tin ; perchloride of tin.— Oxide of copper ; nitrate of copper ; chloride of copper , . . . 195 Solution of bitumen in oil of turpentine . . . .196 Yellow chromate of potash ; bichromate of potash.— Solution of caoutchouc. — Lime-water of gas-works. — Bees'-wax and turpen- tine. — Drying oil and turpentine .... 196 Chloride of zinc (Sir W. Burnett's patent) . . . 197 Iron liquor ....... 198 Boucherie's experiments to determine the relative amount of pro- tection from decay afforded by corrosive sublimate, sulphate of iron, iron liquor, and arsenious acid .... 198 § IV, Modes of applying Preservative agents . 200 Application of the aspirative force of the tree suggested by Dr. Boucherie. — Process of impregnating wood with a liquid by aspi- ration. — Different liquids are unequally absorbed. — A more ad- vantageous 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 . . 201 § V. Other effects of the impregnation of Wood with foreign substances . ' . . . . 206 The hardness af the wood increased .... 207 The flexibility and elasticity of wood preserved . . 207 Experiments of Mr. Hyett on the deflection of larch and beech impregnated with different substances .... 208 Strength of the wood may be increased or diminished . 211 Resinous and non-resinous trees require different treatment . 211 Inflammability and combustibility of wood reduced by impregna- tion with foreign substances . . . . 212 Tendency to warp diminished . . . . .213 Application of colours to wood by the aspirative process . 213 Density of wood increased by foreign substances . . . 215 Tables shewing the specific gravity of prepared larch and beecii 216 Table embodying the principal results of Mr. Hyett's experiments on the best materials for preserving wood . . .219 xii CONTENTS. 224 226 III. DYEING AND CALICO-PRINTING. PAGE Dyeing a chemical art.— Object of dyeing . . - 221 § I. History of Dyeing and Calico-printing . . 222 Dyeing practised from time immemorial in the East. — Tyre cele- brated for its dyers.— Tyrian purple.— Dyers of ancient Greece and Rome 222 Progress of dyeing in Em-ope aiFected by the invasion of the Northern barbarians in the 5th century.— The art did not revive until the 12th or 13th century.— Florentine dyers . . 223 Progress of the art affected by the discovery of America.— Applica- tion of a salt of tin.— Use of logwood and indigo prohibited.— Madder introduced.— Application of mineral colours. — Turkey red 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 ..... Progress of calico-printing in Europe. — Printed cottons and linens of Augsburg.— First print-ground in England. — Calico-printing favoured by the prohibition of the importation of chintzes. — Duty imposed on printed calicos.— We&ring of all printed calicos pro- hibited 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 threepence-halfpenny per square yard repealed in 1831 228 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 machine . . 230 Chemists who investigated the principles of dyeing during the last century. — Application of chlorine for bleaching. — Introduction of mineral colours. — Antimony orange and manganese bronze first "introduced by Mr. Mercer, and the two chromates of lead by M. Koechlin 232 § II. General properties of Vegetable colouring matters 233 Only a few have been isolated in a pure state. — General composi- tion. — Action of humid air. —Action of acids and alkalies. — Many • organic colouring matters are feeble acids. — Lakes. — Tlie attrac- tion of colouring matters for insoluble bases is chemical affinity, and not a mere surface attraction . . . . 233 Action of chlorine, chromic acid, and sulphurous acid on organic colouring matters. — Animal charcoal. — Several colouring matters CONTENTS. Xlll PAGB are oxides of colourless radicals. — Deoxidizing agents. — Other coloiuring matters form colourless hydrurets . . . 238 Colouring matters attach themselves to tissues. — Division of colour- ing matters into two classes. — Mode of applying members of each class to tissues ...... 242 Nature of colour ....... 245 List of vegetable and animal colouring matters . . 247 Alkanet ........ 247 Annatlto ....... 247 Archil., litmus ; turnsole ; cudbear . . . . 248 Barwofod ; camwood ..... 248 Brazil-wood ; sapanwood, Fernambouc wood ; peachwood ; Nica- raguia wood . . . . . . . 248 Catechu or terra Japonica ..... 249 Cochineal ; coccinellin ...... 249 French berries ; Avignon berries ; Persian berries . . 250 Fustet or yellow fustic ...... 250 Fustic or old fustic ...... 250 Indigo. ; indigotin . . . . . . 251 Kermes grains . . . . . . 251 Lac-dye ; stick-lac . . . . . .251 Logwotod . ... . . . . 251 Madder ........ 252 Quercitron ...... 252 Safflower ........ 253 Sandal-wood (red Sanders wood) .... 253 Sumac:h, galls, valonia and saw-wort .... 253 Turmeric ....... 254 Weld ........ 254 Woad 254 List off mineral colours employed in dyeing . . . 254 Antimony orange ... ... 254 Arseniate of chromium ...... 255 Chrome-yellow ...... 255 Chrome-orange ....... 255 Manganese brown ...... 255 Orpiment ....... 255 Peroxide of iron (iron buff) ..... 256 Prussiate of copper ...... 256 Prussian blue ...... 256 Scheele's green (arsenite of copper) .... 256 § IIL General nature of Dyeing processes . 257 Processes for different kinds of fabrics dissimilar . . 257 xiv CONTENTS. PAGE Singeing of cottons by furnace .... 257 Singeing by gas . . . . . . 268 List of operations practised in bleaching cottons . . 259 Bleaching of mousselin de laines .... 260 Preparation of silk for printing .... 261 Colouring matters must be applied in solution . . - 261 Arrangement of all dyeing processes under four heads . 262 Nature of the processes for applying mineral colours . 263 Modes of applying colouring matters which are soluble in water 265 Mordants ....... 266 The mordant should exist on the cloth about to be dyed in an n- soluble form . . . . . . 267 An insoluble subsalt is often produced through the desiccation of the mordant on the cloth .... 267 Cases in which the desiccation of the mordant may be omitted 269 Reasons for removing all excess of mordant . . 269 Alterant ....... 270 Dyeing from a mixed solution of colouring matter and mordant 272 Different colours of the compounds of the same colouring mater with different mordants ..... 274 Mordants in common use ..... 275 Alumina ....... 276 Alum ....... 276 Basic alum . . . . . . 278 Red liquor and acetate of alumina. — 'Preparation of red liquor — Composition of common red liquor. — Decomposition of red liqior by heat. — Acetate of alumina .... 280 Aluminate of potash ..... 285 Tin mordants. — Peroxide of tin. — Perchloride. — Mixture of pjr- chloride and pernitrate. — 'Pink salt. — Stannate of potash . 287 Protoxide of tin. — Salts of tin. — Plum spirits . . 289 Iron mordants. — Acetate of iron. — Iron liquor. — Peroxide of inn. — Pernitrate. — Sub-pernitrate. — Basic persulphate . 291 Assistant mordant ..... 294 Brightening action of dilute acids on the tints of compounds of coloir- ing matters and mordants. — Acids may act by preventing the at- tachment of an excess of colouring matter. — Disintegration of he mordant the principal effect of the acid. — Acids may unite p;r- manently with the compound of colouring matter and mordant 294 Dunging. — Object of dunging. — Process. — Composition of ccw- dung. — Action of the dung .... 303 Dung substitute. — Mode of preparation. — Cleansing liquor. — Mide of applying dung substitute .... 307. CONTENTS. XV PAGE Branning . . . . . , . 312 Preparation of dyeing infusions . , . . . 313 Dyeing. — Dye-beck ..... 314 Modes of dyeing with insoluble colouring matters . . 315 Mode of imparting a colour by partially corroding the fibre . 315 TemperatTire of the dye-beck ..... 316 Finishing operations on calico printed and dyed with madder colours. — Dash-wheel. — Rinsing machine. — Clearing. — Water extracter. — Starching machine. — Steam drying machine. — Calen- dering ....... 318,. Purity of the water employed in dyeing .... 32f § IV. Calico-printing processes . . . $31 Characteristics of the six different styles of printing processes ^31 Block-printing. — Rainbow style . . . . . 3^3 Stereotype printing plate ..... 3^ Perrotine ....... 33^- Cylinder printing ...... 336 Modes of engraving copper rollers .... 338 Press printing . . . . . . ' . 340 Surface printing ...... 342 Thickeners ....... 343 Madder style. — Printing. — Drying. — Ageing. — ^Dunging.- — Dyeing. — Clearing ....... 347 Madder purple of two shades .... 353 Madder red of two shades ..... 354 Madder reds and purples combined .... 355 Other colouring matters applied in the madder style. — Quercitron. — Madder and Quercitron. — Logwood. — Cochineal . . 357 Topical and steam colours. — Topical black. — Catechu brown. — Spirit purple. — Spirit chocolate. — Spirit pink. — Spirit yellow. — Topical blues ...... 359 Steam colours. — Previous preparation of the cloth . . 368 Steam black. — Steam red. — Steam pui^ple. — Steam yellow and orange. — Steam blue. — Steam green , . . 370 Process of steaming ...... 379 Design in steam colours entirely .... 381 Design in madder colours and steam colours combined . . 382 Modes of applying mineral colouring matters as grounds and as figures . . . . . . . 383 Padding machine ...... 384 Prussian blue. — Chrome-yellow. — Chrome- orange. — Iron buff. — Manganese bronze. — Scheele's green . . . 384 xvi CONTENTS. PAGE Example of the combination of mineral colours with madder and steam colours . . . . • • .392 Resist style 393 Fat resists 393 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 395 Resists for the colouring matter. — Chiefly adapted to indigo. — Ma- terials employed. — Course of operations. — Mode of action of salts of copper and mercury. — Action of sulphate of zinc. — Blue-vat. — Receipts for resist pastes ..... 399 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 buif on a blue ground.— Figure in buff on a green ground 404 Lapis or neutral style. — Resist red.— Course of operations. — Resist black. — Process for obtaining figures in light blue and a madder colour on a blue ground.— The same with a white figure.— Design in chrome-orange, white and crimson on a blue ground. — Choco- late ground neutral style ..... 406 Resist for catechu brown . . • • .411 Principle of the discharge style . . . . 413 Dischargers for colouring matters . . . .413 White discharge by chloride of lime and an acid . . 413 Dischargers for Turkey red and other madder colours . . 414 Imitation of Bandanna handkerchiefs . . . 415 Coloured designs on Turkey red gromid. — Chrome yellow and Prus- sian blue on red . . • • • .416 Chromic acid discharge for indigo . . . . 418 Combination of madder style with the preceding . . 419 Dischargers for mineral colouring matters. — For Prussian blue. — For manganese brown.— Coloured designs on manganese ground. Dischargers for chrome-yellow, chrome-orange, and iron buff 420 Dischargers for mordants. — Course of operations practised in this style of work ...... 424 Combination of the indigo resist style with the preceding . 427 Combined mordant and discharger .... 428 China blue style ...... 430 Printing of mousselin de laines, silks, chalis, &c. . . 437 Manderining style . . . . . ' . 441 APPLIED CHEMISTRY; IN MANUFACTURES, ARTS, AND DOMESTIC ECONOMY. PRELIMINARY OBSERVATIONS. Heally valuable improvements of old and inven- lioos of new processes in the chemical arts and ma- nufactures are not often the result of chance, in the i>j'e.vent advanced state of chemistry, but of a logical apT lication of recognised chemical principles of greater VI less generality. Such has been the case since the existence of chemistry as a distinct science pos- s?v;d of general laws. The surprising attainments of the ancients in cer- i.!-. i chemical arts would lead us to infer that pro- ( "ss(-;s may be invented, and even successfully applied, Without the smallest conception of the principles on which they depend. The ancient Egyptians and Pi'o nicians were not only acquainted with the means > . o aracting iron, copper, gold, silver, lead, and tin i'i oia the ores containing these metals, 'but with com- B 2 PRELIMINARY OBSERVATIONS. plicated processes for the preparation of several me- tallic compounds. They extracted soda from the soil in which that alkali naturally exists, and under- stood the means of purifying it: they procured pot- ash from the ashes of plants, and made soap by combing- the alkalies with oils and fats. They were acquainted with the mode of converting an alkaline carbonate into a caustic alkali by the ac- tion of quick-lime, and even took advantage of this property of lime to give to soda (carbonate of soda) ^)'aegree of causticity which deceived the purchasers of this article as to its real value. The arts of making earthenware, glass (both colourless and co- loured), porcelain, and various pigments, and cer- tain processes in dyeing, were brought to a state of perfection not exceeded, nay, in some instances, scarcely equalled, by artists of the present day. These and other processesj xc not only invented without the aid of science, tli-at 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 discover the causes of the va- ried phenomena presented in the different operations. The successive improvements fortunately achieved in some of the processes were contrived, like each ori- ginal process itself, by chance, and consequently, in general, at the expense of great labour ; the expe- rimentalist being guided in his researches for im- provements by no fixed principles or general laws. Where improvements are to be the result of acci- dental observations, they must of necessity be rarely made. The Chinese, it is true, practise certain chemical arts ^ with surprising success: but these PRELIMINARY OBSERVATIONS. 3 arts are no further advanced now than they have been for ages past; not because they have attained perfection, but from the want of a 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 losi -^'it alto- gether. This is the reason, we appi Jiena, of the loss of some of the most refined processes of the ancients during the middle ages. But since chemistry has existed as a scieiic. founded on certain laws, and since the properties of individual substances have been so minutely stu- died that the action of two or more bodies on each other in certain circumstances can be partly pre- dicated before ascertained by experiment, new pro- cesses are devised and others improved by a scien- tific deduction from " ■ agnized principles, and from the known properties the substances employed in the art or manufacture. Refined as were some of the processes of the an- cients, there are those practised in the present day which it is difficult to conceive could have been invented by any number of hazard experiments on substances presented by nature. They were devised and improved by a logical induction from known principles or admitted theories. The greater num- ber of our calico-printing processes are illustrations of our assertion. For instance, we cannot 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, B 2 4 PRELIMINARY OBSERVATIONS. and afterwards of an acid, of a substance by which, when applied in a proper manner, the calico-printer is enabled to produce a white pattern on a piece of cloth dyed 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 towards the close of last century by Le- blanc and others, which is scarcely second in im- portance to any chemical manufacturing process, could hardly have been devised otherwise than by a series of experiments conducted on certain che- mical 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 process for obtaining sulphuric acid by the combus- tion of sulphur with nitre, which was contrived by Lefevre and Lemery soon after the developement, by Stahl and Beccher, of the theory of phlogiston. According to that theory all combustible bodies are compounds of phlogiston, or the principle of in- PRELIMINARY OBSERVATIONS. 5 flammability, (which is parted with in the act of combustion,) and some elementary basis, which is, ill fact, the material product of the combustion. The latter is now known to be the compound body, being composed of the combustible matter and oxy- gen ; the act of combustion is merely the combi- nation of oxygen with the combustible. But con- sistently with the then prevailing theory of phlo- giston, sulphur is a compound body, being composed of phlogiston united with (what is now termed) sul- phuric acid: to procure the latter, therefore, it be- came necessary to withdraw phlogiston from the sulphur. Now nitre was considered to be a sub- stance 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 erroneous; 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; after- wards they become somewhat more complicated. The reason why the process was successful, while the theory on which it was founded is false, is obvious. The terms a dephlogisticating body (on the theory of phlogiston), and an oxidating body (according to our present views), are synonymous : as are also a dephlogisticated and an oxidated substance. It cannot be denied, however, that valuable pro- 6 PRELIMINARY OBSERVATIONS. cesses and improvements have been devised of late years independently of chemical hypotheses and prin- ciples. The amalgamation process of Hernando Ve- lasquez for obtaining silver from the ore (practised in Mexico) must ever be considered a wonderful in- stance of the discovery, by chance, of a process de- pendent in its details on complicated chemical agen- cies. The inventor was entirely unacquainted with theoretical chemistry, and was led to his process by experiment after experiment without connection, 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 Sonne- schmidt. Instances like this are, however, very rare. Although many processes in the chemical arts are dependent for their successful practice chieHy on a knowledge of principles, yet, in general, the ambition of those engaged in working the process is to attain dexterity in the mechanical operations, without the smallest endeavour to comprehend the most obvious principles of their process. Although chemistry is making rapid advances, many of the arts dependent on the science are stationary, the artisan or manufacturer being, generally, too ig- norant of chemistry to know where to look for im- provements. By this neglect of the practical man, scientific chemistry is also much retarded. In a dye- house and a calico-print-work, for instance, how many interesting phenomena pass unobserved, or at least without being investigated, which, if carefully exa- mined by a scientific chemist, might prove the. sources CHEMICAL AFFINITY. 7 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 re- ference, and for the convenience of those who have not especially studied the principles 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 combi- nation of different substances. All other important theoretical considerations affecting the various prac- tical subjects treated of in this work will be ad- verted 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 contain one kind of mat- ter only. According to the present state of our knowledge, the number of elements does not ex- ceed 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 sub- 8 PRELIMINARY OBSERVATIONS. stances now considered as elements may hereafter turn out to be compound. But until such is prov- ed to be the case, it is proper to consider them as simple substances. Every substance in nature, then, is either an ele- ment, or else it results from the combination of two or more elements with each other. This union of the elements does not take place indiscriminate- ly: some of them when brought into contact exhi- bit a remarkable proneness to unite, while others may be mixed most intimately without the occur- rence of combination. Peculiar attachments and in- differences certainly subsist between different sub- stances. The former may be conveniently distin- guished as chemical affinity, or chemical 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 chemical affinity, the result- ing substance is called a chemical compound^ to distinguish it from a mechanical compound. The latter is a mere mixture of different 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. Chemi- cal 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 AFFINITY. 9 chemical characters of its constituents, and in the act of combination there is commonly a very ob- vious change^ even in the most general, of physical properties. Mechanical compounds, which consti- tute by far the greater number of natural substances, are on the contrary indefinite mixtures of element- ary bodies or chemical compounds of the elements, retaining both the form and the properties of their constituents. The atmosphere around us, for ex- ample, is a mechanical mixture 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 compounds : 1°, quartz^ which is a chemical combination of two elements, silicon and oxygen; 2°, felspar, which is composed of four ele- ments, silicon, oxygen, potassium, and aluminum ; and, 3°, mica, composed of six elements, namely, si- licon, oxygen, iron, aluminum, magnesium, and po- tassium. The three minerals, quartz, felspar, and mica, each a chemical combination, thus constitute the rock granite by their mechanical admixture. The nature of chemical affinity and the characters of chemical compounds may be conveniently consi- dered under the four following heads : — 1°, Che- mical affinity is exerted with different degrees of force between different substances. 2°, The union takes place in certain fixed and definite proportions. 3°, The resulting compound always differs essen- 10 PRELIMINARY OBSERVATIONS. tially 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 differ e7it 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 me- tallic state at the highest temperature to which we can expose it. It is therefore reasonably inferred that oxygen has a more powerful affinity for cop- per than for silver. Again, oxide of copper is re- duced to the state of metallic copper with the great- est 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 power- ful 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 subli- mate), the latter is decomposed, metallic mercury is precipitated, and a proportional quantity of cop- per is dissolved, uniting with chlorine to form chlo- ride of copper. But chloride of copper may be de- composed in a similar manner by metallic tin, and CHEMICAL AFFINITY. 11 chloride of tin by metallic zinc. The relative affi- nity of these metals for chlorine may therefore 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 mentioned, while a solution of chloride of mercury is decomposed by each. A series of tables was contrived by Geoffrey and Bergmann, founded on such experiments as these, intended to exhibit the order of affinity of different bases* for an acid, and 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 acid. 1. Barytcs, 5. Lime, 2. Strontian, 6. Magnesia, 3. Potash, 7. Ammonia. 4. Soda, Barytes, the first in the list, is capable of taking sulphuric acid from the sulphate of either of the bases which follow, while sulphate of barytes is not decom- posed by any other base. Potash has a stronger affinity for sulphuric acid than the bases which fol- low, but not so strong as that of barytes. The ex- periments are supposed to be made on aqueous so- lutions of the several sulphates. * By a base is meant an alkali, or a metallic oxide which has a ten- dency 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. 12 PRELIMINARY OBSERVATIONS. Such tables, however, shew the order of decom- position, and the relative force of affinity, in one set of conditions only ; for, when the same two substances are brought together under different circumstances, very different reactions may ensue. Of this Berg- mann himself was aware, and hence gave two lists or columns in some of his tables of affinity; one shewing the order of decomposition when the sub- stances are mixed together dissolved in water, as above, and the other when mixed in the 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 decomposition 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 affi- nity for lime than for ammonia, or carbonic acid a stronger affinity for ammonia than for lime. But if the conditions in which the nitric acid, carbonic acid, lime, and ammonia are brought together are altered, very different results take place. On mixing aqueous solutions of nitrate of lime and carbonate of am- monia, carbonate of lime is precipitated, and nitrate of ammonia remains in solution. Again, carbonate of potash dissolved in water is instantly decomposed 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 potash than carbonic acid does. But if a stream of car- CHEMICAL AFFINITY. 13 bonic acid gas is passed through a solution of ace- tate 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 mu- tual 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 decomposition 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 substance. These and many other examples, which might be adduced if necessary, shew that though chemical affinity is exerted between different bodies with dif- ferent 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 limit- ed on both sides, has been already alluded to as a distinction between a chemical and a mechanical compound (page 8). Common salt, for instance, by whatever process it may be formed, is invaria- bly 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 14 PRELIMINARY OBSERVATIONS. carbonate of lime, wlietlier formed ages ago by the hand of nature, or quite recently by the chemist, whether in the form of white marble, chalk, or a stalactite, whether in the six-sided prism of arra- gonite, or in the rhomboidal crystal of calc spar, is always composed of 43-7 parts of carbonic acid and 5 6 '3 parts of lime. That the composition of chemical combinations is always fixed and invari- able, is constantly borne out by analyses; and from this definite nature of chemical combination is de- rived in a great measure the character of chemis- try as an exact science. The same element combines with very different quantities of different substances. This is shewn in the following table of the composition of water, sulphuretted hydrogen, hydrochloric acid, and hy- driodic acid, each of which substances contains hy- drogen as a common constituent. Water. Sulphuretted Hi/drogen. Hydrogen ll'l Hydrogen 5'9 Oxygen 88-9 Sulphur 94-1 100-0 100-0 Hydrocliloric Acid. Hydriodic Acid. Hydrogen..... 2-7 Hydrogen 0-79 Chlorine 97-3 Iodine 99-21 100-6 100-00 By such a mode of expressing the composition of these bodies no simple relation is perceptible be- tween the respective quantities of hydrogen in the different 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 CHEMICAL AFFINITY. 15 of chlorine, and 126 parts of iodine combine re- spectively with 1 part of hydrogen. Now the num- bers 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 potas- sium, 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 compounds are not the same. Thus 8 parts of oxygen 35'5 parts of chlorine 16 parts of sulphur 126 parts of iodine 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 multi- ples of such quantities. These numbers are called combining proportions or equivalents. The latter term is employed to signify that the combining pro- portion 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 equivalent to each other, as they have an equal power in combining with, and altering the nature of, 39 parts of po- tassium. , 1 part of hydrogen, combine with parts of lead, ' 32 parts of copper, 39 parts of potassium. 16 PRELIMINAKY OBSERVATIONS. Hitherto we have considered the equivalent num- bers with reference to hydrogen as unity, but this is quite arbitrary, 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 considered 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 follow- ing table contains a list of all the elements which have been discovered up to the present time, with their combining numbers on both the hydrogen and oxygen scales. TABLE OF CHEMICAL EQUIVALENTS. Names of Ele- ments. Equivalents. Names of Ele- ments. Equivalents. Oxygen = 100. Hydro- gen = 1. Oxygen =z 100. Hydro- gen Aluminum 171-2 13-7 Columbium 2307-4 1 84-9 Antimony- 1612-9 129-0 Copper 395-7 31-7 Arsenic 940-1 75-3 Didymiura ? p Barium 856-9 68-7 Fluorine 233-8 18-7 Bismuth 886-9 71-1 Glucinum 331-3 26-5 Boron 136-2 10-9 Gold 2486-0 199-2 Bromine 978-3 78-4 Hydrogen 12-5 1-0 Cadmium 696-8 55-8 Iodine 1579-5 126-6 Calcium 256-0 20-5 Iridium 1233-5 98-8 Carbon 75-0 6-0 Iron 339-2 27-2 Cerium 574-7 46-05 Lantanum ? ? Chlorine 442-6 35-5 Lead 1294-5 103-7 Chromium 351-8 28-2 Lithium 80-3 6-4 Cobalt 369-0 29-6 Magnesium 158-3 12-7 CHEMICAL AFFINITY. 17 Names of Ele- Equivalents. Mames oi Me- incuts* Equivalents. Oxygen = 100. Hydro- gen = 1. Oxj'gen = 100. Hydro- gen 345-9 27-7 Silver 1351-6 108-3 JVEGrcury 1265-8 101-4 290-9 23-3 ^VTolybdcnum 598-5 48-0 SIf vmrf inim 547-3 43-8 369-7 29-6 Sin 1 n niiT* 201-17 16-1 Nitrogen 175-0 14-0 Tellurium 801-76 64*2 Osmium 1244-5 99-7 Thorium 744-9 59-8 Oxygen 100-0 8-0 Tin 735-29 58-9 Palladium 665-9 53-4 Titanium 303-66 24-3 Phosphorus 392-3 31-4 Tungsten 1183-0 94-8 Platinum 1233-5 98-8 Vanadium 856-9 68-7 Potassium 489-9 39-2 Uranium 2711-4 217-3 Rhodium 651-4 52-2 Yttrium 402-5 32-2 Selenium 494-6 39-6 Zinc 403-2 32-31 Silicon 277-3 22-2 Zirconium 420-2 33-7 The principal law which governs chemical combi- nations is, that bodies unite chemically with each other onli/ in the proportion of their equivalents, or in multiples of their equivalents, and in no intermediate proportions. This law is well illus- trated by the five compounds which are formed by the union of oxygen and nitrogen. The first of these, protoxide of nitrogen, or nitrous oxide, con- tains 14 parts of nitrogen and 8 of oxygen; that is, one equivalent of each constituent. The second combination of these elements, deutoxide of nitro- gen, or nitric oxide, contains 14 parts of nitrogen and 16 of oxygen; that is, two equivalents of oxy- gen 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 c 18 PRELIMINARY OBSERVATIONS. of oxygen or four equivalents. The fifth and last, nitric acid, of which aqua-fortis of commerce is a solution in water, is composed of 14 parts of nitro- gen 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 =: 39, and one eq. of oxygen — 8. Now 47 parts of potash combine with exactly 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 40. To form neutral sulphate of potash, consisting of one eq. of potash and one eq. of sulphuric acid, 47 parts of potash combine with exactly 40 parts of sulphuric acid, and the equivalent of the re- sulting 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 con- taining respectively one, two, and three equivalents of water. Here is, therefore, an example of com- bination in multiple proportions between bodies CHEMICAL AFFINITY. 19 themselves compound. However great may be the number of the equivalents of the elements of a com- pound body, the universality of the law that the equivalent of the compound is the sum of the equi- valents 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 mecha- nical admixture. In the former, the change is never wanting ; in the latter, the properties of the mixture are the mean of those of its constituents. We should not suppose from its appearance that common salt is a compound body : much less that this harmless sub- stance 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 pro- perty of taking fire when moistened with water. Sometimes a change in density and form at- tends the chemical combination of two substances. Thus two gases may give rise to a solid, as hap- pens 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 charcoal form gases by combining with hydrogen gas. Gases sometimes unite, however, without any alteration in bulk. When combina- tion takes place among solids and liquids with the formation of a solid or liquid, condensation is a c 2 20 PRELIMINARY OBSERVATIONS. more frequent result than expansion; and, if otlic evidence of chemical combination is wanting, tha: of the occurrence of a condensation may be consi- dered conclusive. Thus the contraction which re- sults when water and alcohol are mixed in certaii proportions, is considered, of itself, a sufficien-, proof of the chemical union of the water with th« alcohol. A change of colour very frequently attends che- mical combination ; sulphur forms a red and a blacl compound with mercury, black compounds with lead and copper, a white compound with zinc, and two yellow compounds with arsenic. Iodine, whose va- pour is violet-coloured, forms a white compounc with copper, a yellow compound with lead, and i scarlet compound with mercury. An example of change in properties is afforded, in short, by al- most every case of chemical combination. Change of temperature is a frequent result of chemical action. It is said that the direct chemi- cal combination of two or more substances never occurs without the developement of a certain amoun^. of heat, on which circumstance depend all our ordi- nary artificial modes of obtaining heat. The produc- tion of heat in the act of combination may be some- times referred partly to the condensation whicli usually takes place, the compound formed having a smaller specific heat than its constituents; but in a great many cases this explanation is inadmissible. The true cause of the evolution of heat in chemical combination still . remains to be accounted for. The intensity of the heat developed through the com- bination of two bodies differs greatly, according to CHEMICAL AFFINITY. 21 the circumstances in which the combination takes place; but it is a remarkable fact that the quan- tity 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 pla- cing the mixed gases in contact with some earthy mould. In the first case, the intensity of the heat produced is sufficient to fuse with facility many substances which are quite infusible at the highest temperature of a smith's forge: in the se- cond case, the temperature rises very little above that of the surrounding atmosphere. But there is reason to believe that the actual quantity of heat developed is the same in both cases for like quan- tities of the gases: the difference is only in inten- sity or state of concentration; the slowness of the action in the second case allowing 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. The superior vivacity of the combustion of tallow, a match of wood, &c. in oxygen gas, compared with air, depends entirely on the same circumstance. A piece of charcoal burns with far more heat and light in oxygen gas than in air; but it unites with oxygen, or is consumed, pro- portionally faster. 4. Chemical union may take place indirectly hy substitution, or directly.— The following exam- ples will serve to illustrate this proposition. When 22 PRELIMINARY OBSERVATIONS. the two component parts of common salt, cMorine and sodium, are placed in contact, a direct combi- nation instantly ensues. But the union of the chlo- rine 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 con- tact with soda (a compound of sodium and oxy- gen). Again, if a mixture of iron filings and flow- ers of sulphur is projected into a crucible heated to dull redness, a direct combination of iron and sulphur ensues, the sulphuret of iron being formed. But the same compound is formed when a solution of sulphuret 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 charac- terized by two important circumstances. While union is taking place on the one hand, there is necessarily decomposition on the other; for the sub- stances 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 hydrochloric acid and soda, there must be a decomposition both of the hydrochloric acid and the soda, in order that the chlorine and so- dium may unite. And when sulphuret -^f xron is formed by mixing sulphuret of potassium with chlo- ride of iron, the sulphur and iron cannot unite without a decomposition of the sulphuret of potas- sium and of the chloride of iron. As there are two disunions, so are there likewise, generally, two combi- CHEMICAL AFFINITY. 23 nations. When hydrochloric acid is made to act on soda, union is effected, not only between the chlorine and sodium, but the hydrogen of the hydrochloric acid unites at the same moment with the oxygen of the soda, to produce water. Chloride of sodium and water, therefore, are the products of the action of hy- drochloric acid on soda. The manner in which the decompositions and combinations occur is more clearly exhibited in the subjoined diagram. The first co- lumn contains the names of the original substances ; the second, the names of their constituents ; and the third, the names of the compounds which are formed, the lines indicating how the constituents of the ori- ginal substances become arranged. I. XL III. Hydrochloric | Hydrogen —-^ Water acid \ Chlorine Soda /^^y^^" \ Soda Chloride of sodium. In like manner, as two decompositions occur when sulphuret of potassium and chloride of iron are made to act on each other, so are there like- wise two combinations ; for at the same time that the sulphur of the sulphuret of potassium unites with the iron of the chloride of iron, the chlorine of the lat- ter unites with the potassium of the sulphuret of potassium to form chloride of potassium. The an- nexed diagram will illustrate these changes. Sulphuret of potas- f Potassium ^ Chloride of potassium sium \ Sulphu ^1 , . 1 o . f Chlorine Chloride of iron J (. Iron . — . Sulphuret of iron. 24 PRELIMINARY OBSERVATIONS. Such reactions as these are described as double decompositions or double substitutions. But an- other 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 combination 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 Hydriodicacid. In this example there is a single union and a single decomposition; or, in fact, merely a substitu- tion of iodine for sulphur in the sulphuretted hy- drogen. A great number of compounds may be readily formed by reactions of this kind, all at- tempts to obtain which by direct combination 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 che- mical affinity. One of the characters of a chemical union is certainly in some degree fulfilled in solu- tion, namely, change in properties; but several cir- cumstances manifest a difierence 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 la- J SOLUTION. 25 tent by the dissolved substance, as always hap- pens 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 combine with any quantity of com- mon salt less than 37 per cent, of the weight of the water; and the solution has the same appear- ance, whether it contains a large or a small propor- tion of salt. Water, it is true, has a constant maximum solvent power for every soluble salt at a particular temperature ; but the quantity of water and the quantity of salt in solution bear, in gene- ral, no simple relation to the chemical equivalents of these substances. Again, chemical combination takes place with so much the more energy as the properties of the combining substances are more opposed; but solution, on the contrary, with a readiness corre- sponding to their similarity in properties. Thus, to dissolve combustible bodies containing a large pro- portion 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 differ- ence exists, therefore, between the act of solution and that of chemical combination; the former be- * 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. 26 PRELIMINARY OBSERVATIONS. ing 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 tem- perature. 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 tempera- tures below 230° Fahrenheit. In another case, that of sulphate of soda, the solubility of the salt in- creases rapidly up to the temperature 92° Fahren- heit, at which it is at the maximum: the solution at that temperature contains 52 parts of dry sul- phate to 100 parts of water, but at a higher tempe- rature water is incapable of dissolving so large a pro- portion of that salt. In aU other cases, so far as is known, the amount of a salt dissolved increases with the temperature, unless a decomposition and forma- tion 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 crystalli- zation. When a solution of a salt saturated (con- taining 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 tempera- ture : 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 PROXIMATE AND ULTIMATE CONSTITUENTS. 11 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 developement 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 of potash, or the hydrate of chloride of calcium. Proximate and ultimate constituents^ and Sym- hols. 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 ulti- mate constituents are sulphur, oxygen, magnesium : the proximate constituents are sulphuric acid and magnesia: thus, Sulphate of magnesia 28 PRELIMINARY OBSERVATIONS. The composition of crystallized alum is more com- plex: thus, Proximate Constituents. Alum Sulphate of alumina Sulphate of potash ^ Sulphuric I acid 1 Alumina - Sulphuric ^ acid 1 Potash Ultimate Constituents. ^ Sulphur ^ Oxygen ^ Aluminum I Oxygen t Sulphur I Oxygen ^ Potassium ^ Oxygen \ Water $ Hydrogen ( Oxygen. Now the composition of crystallized alum may he expressed in so many parts of sulphur, oxygen, alumi- num, potassium, and hydrogen ; or in so many parts of sulphuric acid, potash, alumina, and water; 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 not a mere mechanical compound, should include, if possible, the atomic composition 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 compo- sition alone, represented either according to the proximate or ultimate constituents. The reasons of this will be obvious from the considerations offered PROXIMATE AND ULTIMATE CONSTITUENTS. 29 at page 1^ 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 Atomic 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 lOQ-Q The readiest method of representing the composi- tion of a compound body is by the association of symbols of its elementary or proximate constituents. Each elementary substance is represented by a par- ticular 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 Ft, and palladium by Pd; C being the symbol for carbon, calcium is represented by Ca, chlorine by CI, and cobalt by Co; the small letter is significant only when in conjunction with the large letter. The following table includes the symbols of all the elementary substances known. 30 PRELIMINARY OBSERVATIONS. TABLE OF SYMBOLS. Elements. Symb. Aluminum Al Antimony (Stibium) ... Sb Arsenic As Barium Ba Bismuth Bi Boron Bo Bromine B Cadmium Cd Calcium Ca Carbon C Cerium Ce Chlorine CI Chromium Cr Cobalt Co Columbium (Tantalum) Ta Copper (Cuprum) Cu Didymiura Di Fluorine Fl Glucinum Gl Gold (Aurum) Au Hydrogen H Iodine I Iridium Ir Iron (Ferrum) Fe Lantanum La Lead (Plumbum) Pb Lithium Li Magnesium Mg Elements. Manganese Mercury (Hydrargyrum) Molybdenum Nickel Nitrogen Osmium Oxygen Palladium Phosphorus Platinum Potassium (Kalium) .. Rhodium Selenium Silicon Silver (Argentum) Sodium (Natrium) Strontium Sulphur Tellurium Thorium Tin (Stannum) Titanium Tungsten or Wolfram Vanadium Uranium Yttrium Zinc Zirconium 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, hut 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 CHEMICAL SYMBOLS. 31 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 oxygen ; or else a figure shewing the number of equivalents may be placed immediately before the symbol, thus, 30 ; or, what is preferable, a smaller figure may be placed after the symbol, either above or below it, thus, 0^ 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 oxy- gen, which is the alkali potash. H + Cl or HCl represents hydrochloric acid, composed of one equi- valent of hydrogen and one equivalent of chlorine. SO3 signifies sulphuric acid, a compound of one equi- valent of sulphur with three equivalents of oxygen. Something more may be expressed in symbolic no- tation than the names of the elements of a compound body and the numbers of their equivalents ; the con- stitution of the compound, or the mode in which the elements are arranged, may also be represented. The formula, Fe S O4 expresses truly the composition of proto-sulphate of iron (copperas), but not the ar- rangement of the elements ; on the contrary, the for- mula FeO + SO3 or FeO, SO3 signifies that the salt in question is composed of oxide of iron and sulphuric acid, the + sign, or the comma, indicating a distribu- tion of the elements of sulphate of iron into its proxi- mate 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 to 32 PRELIMINARY OBSERVATIONS. which it is immediately attached; but a large figure placed before the symbol, like a co-efficient in algebra, affects the whole compound expressed, or at least all the symbols before the first comma, or plus sign. Thus 3NO5 and 2SO3 signify three equivalents of nitric acid and two equivalents of sulphuric acid. The formulte 2H0, SO3 and 2H0 + SO3 express not twice HO, SO3 but a compound of two equivalents of water with one equivalent of sulphuric acid; the SO3 not being affected by the figure 2 at the begin- ning, 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 (HO, SO3) represents two equivalents of hydrated sulphuric acid, and 2(MgO, SO3 4- 7H0) two equivalents of crystal- lized sulphate of magnesia. The following formulse of some minerals afford examples of the application of these rules : Felspar, KO, SiOj + Al^Og, 3S0^. Analcime, 3NaO, SSiOj + SAl^Og, 2Si03 + 6H0. Apophyllite, 8(CaO, SiOg) + KO, 2Si03 + 16H0. To avoid indistinctness or confusion from the great length of the formulae of some bodies, several abbre- viations have been introduced. When two equiva- lents 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 hydro- gen. 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 CHEMICAL SYMBOLS. 33 sulphuric acid, and K potash; therefore KS stands for sulphate of potash. Alum is represented by K S, Al 3S + 24H. Sulphur in a compound is some- times represented in a similar manner by a comma placed over the symbol of the other element, sele- nium 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, for citric acid. Tar for tartaric acid, and F for formic acid. 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. D 34 TABLE OF EQUIVALENTS. I. AC Acetic (dry), A = (C4H3O3) 51-0 Arsenic, As 0^ 115*4 Benzoic, Bz = (C.^H^Og) 113-0 Boracic, B O3 34-9 Bromic, BrO^ 118-5 Carbonic, C0„ 22-0 Chloric, CI Og 75-5 Citric, C=:(C4H2 0 J... 58-0 Formic, F = (C2HO3)...37-0 Gallic, G = (C^ HO3)... 67-0 HydriodicHI 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 IDS. Hypermanganic, Mn2 0^ 112-0 Hyposulphuric, O5 ... 72-3 Hyposulphurous, Og •-• 48-3 Iodic, I O5 r 166-6 Lactic, L = (CgHgOg) 81-0 Malic, M = (CgH^Og) 116-0 Manganic, Mn O3 51-7 Nitric, N O5 54-0 D» hydrated, H 0, NO^ 63-0 Oxalic, C, O3 36-0 Phosphoric, PO5 71-5 Silicic, Si O3 46-3 Sulphuric, S O3 40-1 D» hydrated, H 0, S O3 49-1 2(H0, SO3) 98-2 Sulphurous, S 0„ 32-1 Tannic, Tn = (C.sH^O,) 285-0 Tartaric, Tar — (CbH.O,,) 132-0 II, B Alumina, Al^, O3 51-5 Ammonia, N H, 17*0 Antimony, oxide of, 153*0 Barytes, BaO 76-7 Chromium, oxide of, Cr„ 03 102-4 Cobalt, oxide of, Co 0 ... 37-6 Copper, protox. of, Cu 0 39-7 Copper, suboxide of, Cun 0 71*4 Iron, peroxide of, Fe2 O3 78-4 Iron, protoxide of, Fe O 35-2 Lead, protoxide of, Pb 0 111-7 Lime, Ca 0 28-5 Magnesia, Mg 0 20-7 A.SES. Manganese, protoxide of, MnO 37-7 Mercury, oxide of, Hg O 109-4 Mercury, suboxide of, Hg2 0 210-9 Nickel, oxide of, Ni 0 ... 37-6 Platinum, oxide of, Pt 0 106-8 Potash, KO 47-3 Silver, oxide of, Ag 0 ... 116-3 Soda, Na 0 31-3 Strontian, Sr 0 51-9 Tin, peroxide of, Sn Og ... 74-9 Tin, protoxide of, Sn 0 ... 66-9 Zinc, oxide of, Zn O 40*3 35 GAS ILLUMINATION. § I. History of the Progress of Gas Illumination. — 11, Composition of Coal. — III. Hydrocarbons. — IV. Process of making Coal Gas.— V, Secondary products of the Coal Gas Manufacture.— VT. Oil Gas. —VII. Resin Gas.— VIII. Mode of Burning Gas.— IX. Economy of Gas Illumination. — X. Modes of estimating the Illuminating Power and Purity of Light-Gas. — XI. Regulators and Meters. Naphtha- lized Gas. Of the numerous services which chemistry has rendered domestic economy, there is certainly none which possesses more general importance and in- terest, and none that has been more fully or more successfully developed, than that of lighting by means of gas obtained by the destructive distillation of car- bonaceous substances. The process of making gas from such bodies is simple, and an outline of it may be given in a few words. The material commonly employed as the source of gas is coal^ that being the most accessible ; but any substance of a resinous, fatty, or bituminous nature may also be made use of. Such bodies contain a large proportion of carbon and hydrogen, with, rela- tively, a small amount of oxygen ; the two former elements are the essential constituents of gas for illu- d2 36 GAS ILLUMINATION. mination. To make gas from coal, that substance is heated to redness in a large cast-iron tube, or retort^ placed horizontally in a furnace ; the volatile matters which are given off from the coal are conducted by a tube from the retort into a receiver called the hydrau- lic main, in which the liquid products of the distilla- tion are, to a great extent, separated from the gaseous products. The former consist of a black oily liquid known as coal tar, and a watery fluid known as the ammoniacal liquor. The gaseous product of the dis- tillation, which is a very heterogeneous mixture, and unfit in its present state to be burned within doors, is purified by transmitting it, in the first place, through cold iron tubes, in which it deposits a fur- ther quantity of condensable matter ; and, in the next place, through milk of lime, or through layers of damp hydrate of lime, to absorb sulphuretted hydrogen and carbonic acid. It is sometimes, lastly, freely washed with water, by which a quantity of ammonia is withdrawn. The gas is then conducted to the gasometer, from whence it is distributed by pipes as may be required. To procure gas from tar, resin, oils, and fats, these substances are introduced, by small quantities at a time, into a retort, which contains pieces of brick or coke heated to redness ; a combustible gas is given off in abundance, and the only purification it requires is cooling, to deposit its more easily condensable con- stituents. HISTORY OF GAS ILLUMINATION. 37 § I. HISTORY OF THE PROGRESS OF GAS ILLUMINATION. Although the application of the gases produced by the destructive distillation of pit-coal as a means of procuring artificial light is of modern invention, yet the germ of it may be traced back nearly two hun- dred years. In the year 1659, Thomas Shirley is said to have attributed the exhalations from the burning well of Wigan, in Lancashire, to the sub- jacent coal-beds ; and, soon after, Mr. Clayton, rector of Crofton, at Wakefield, in Yorkshire, actu- ally prepared gas by the distillation of coal. In a letter addressed to the Eoyal Society, May 12, 1688, (''giving an account of several observa- tions made in Virginia, and in the voyage thither, more particularly concerning the air,'') speaking of the thunder in Virginia and its effects, Mr. Clay- ton observes, " I have been told by very serious planters, that thirty or forty years ago, when the country was not so open as it is now, the thunder was more fierce; and that sometimes, after violent thunder and rains, the roads would seem to have per- fect coats of brimstone : and it is frequent, after much thunder and lightning, for the air to have a perfect sulphureous smell. Durst I offer my weak reasons when I write to so great masters thereof," (meaning the council of "the Society,) " I should here consider the nature of thunder, and compare it with some sulphureous spirits which I have drawn from coals that I could no way condense, yet were in- flammable ; nay, would burn after they passed 38 GAS ILLUMINATION. through water, and that seemingly fiercer, if they were not overpowered therewith. I have kept of this spirit a considerable time in bladders ; and though it appeared as if it were only blown with air, yet, if I let it forth and fired it with a match or candle, it would continue burning until all were spent." Phil. Trans. 1693, No. 201, page 788.* About the year 1770, a spontaneous evolution of gas took place at a colliery near Whitehaven, belong- ing to Sir James Lowther. It caught fire on the approach of a lighted candle, and afforded a flame of more than two yards in height. To prevent an- noyance to the workmen, it was conducted from the * The Philosophical Transactions for 1739 contains a letter on the " spirit ofcoak," from the same author, addressed to the Hon. Robert Boyle, communicated hy Dr. Rohert Clayton, Bishop of Cork and Or- rery. In this he enters more minutely into the products of the distilla- tion of coal. As Boyle died in 1691, it was probably written about the same time as the preceding letter. « Having seen a ditch within two miles of Wigan, in Lancashire, wherein the water would seemingly burn like brandy, the flame of which was so fierce that several strangers have boiled eggs over it ; the people thereabouts affirmed, indeed, that about thirty years ago it would have boiled a piece of beef; and that, whereas much rain formerly made it burn fiercer, now, after rain, it will scarcely burn at all. It was after a long-continued season of rain that I came to see the place and make some experiments, and found, accordingly, that a lighted paper, though it were waved all over the ditch, the water would not take fire. I then hired a person to make a dam in the ditch and fling out the water, in order to try whether the steam which arose out of the ditch would then take fire, but found it would not. I still, however, pursued my experi- ment, and made him dig deeper ; and, when he had dug about the depth of half a yard, we found a shelly coal, and, the candle being then put down into the hole, the air catched fire and continued burning. " I got some coal and distilled it in a retort in an open fire. At first there came over only phlegm," (ammoniacal liquor,) " afterwards a black oil," (tar,) " and then, likewise, a spirit arose which I could no ways con- dense ; but it forced my lute or broke my glasses. Once when it had HISTORY OF GAS ILLUMINATION. 39 pit by a tube which terminated four yards above the surface. The gas issued with such force from the ex- tremity of this tube that large bladders might be filled with it in a few seconds; these were fitted up with little pipes, through which the gas might be pressed out and burned when required. A notice of this evolution of gas, or "blower," as it is now termed, was communicated to the Koyal Society in 1773. About the same time, the production of a per- manent gas by the destructive distillation of coal, was noticed by Dr. Hales and by Dr. Watson. The former, by distilling 158 grains of Newcastle coal, forced my lute, coming close thereto in order to try to repair it, I ob- served that the spirit which issued out caught fire at the flame of the candle, and continued burning with violence as it issued out in a stream, which I blew out and lighted again alternately for several times. I then had a mind to try if I could save any of this spirit ; in order to which I took a turbinated receiver, and putting a candle to the pipe of the re- ceiver, whilst the spirit arose, I observed that it catched flame and con- tinued burning at the end of the pipe, though you could not discern what fed the flame. I then blew it out, and lighted it again several times ; after which I fixed a bladder, squeezed and void of air, to the pipe of the receiver. The oil and phlegm descended into the receiver, but the spirit still ascending blew up the bladder. I then filled a good many bladders, and might have filled an inconceivable number more ; for the spirit con- tinued to rise for several hours, and filled the bladders almost as fast as a man could have blown them with his mouth, and yet the quantity of coals distilled was inconsiderable. I kept this spirit in the bladders a considerable time, and endeavoured several ways to condense it, but in vain ; and, when I had a mind to divert strangers or friends, I have fre- quently taken one of these bladders and pricked a hole therein with a pin, and compressing gently the bladder near the flame of a candle till it once took fire, it would then continue flaming till all the spirit was compressed out of the bladder ; which was the more surprising, because no one could discern any difi'erence in appearance between these blad- ders and those which are filled with common air." Such observations as these in an age more alive to economic improvements than that in which they were written might have been the means of the general introduction of gas illumination. 40 GAS ILLUMINATION. obtained 51 grains of incondensable air ( Vegetable Statics). Dr. Watson observes in Ms Chemical Essays^ " I took 96 ounces of Newcastle coal, and, putting tbem into an earthen retort, distilled them with a fire gradually augmented till nothing more could be obtained from them. During the distilla- tion there was frequent occasion to give vent to an elastic vapour which would otherwise have burst the vessels employed in the operation." When the weights of the liquid products of the distillation and the remaining coke were added together, a loss remained of twenty-eight ounces, which Dr. Watson concluded to be the same kind of elastic vapour as had been previously obtained by Dr. Hales. The in- flammability of the gas is also alluded to elsewhere. It is uncertain to whom the credit of first sug- gesting the general employment of gas of any kind as a means of procuring artificial light is to be as- cribed. It is stated in several French works that the idea of employing gas obtained by the destruc- tive distillation of wood for purposes of illumination originated with Philip Lebon, an engineer, in 1785 or 1786, but I.ebon made no communication on the subject to the Institute until the year 1799. In the following year he obtained a patent, and in 1801 published a memoir containing an account of his process under the title, " Thermolampes ou poeles qui chauffent, eclairent avec economie, et offrent^ avec plusieurs produits precieux^ une force motrice applicable d toute espece de machines.'^ Lebon states that all unctuous substances afford, by being distilled, a gas fit for illumination : but he does HISTORY OF GAS ILLUMINATION. 41 not appear to have made any experiments on the distillation of coal ; the material which he generally- employed was wood. As the gas from that source possesses very feeble illuminating power, Lebon's speculation, as might have been anticipated, proved a complete failure ; he abandoned the enterprise, and established a pyroligneous acid manufactory near Versailles, in which he made the combustible gas dis- engaged from the wood subservient to the heating of his retorts. But, while Lebon was making these unsuccessful attempts to introduce gas illumination into France, two individuals were engaged with the same subject in England, with a better promise of success; their source of gas being, not wood, but coal. The first application of coal-gas in illumination appears to have been made in 1792 by Mr. William Murdoch, engineer to Messrs. Bolton and Watt, and then residing at Eedruth in Cornwall; but the ap- plication did not extend beyond his own dwelling- house and offices. Mr. Murdoch removed to Ayr- shire a few years afterwards, where he erected an- other gas apparatus in 1797. The first application of gas on the large scale was made in the following year, when Mr. Murdoch fitted up a gas-work at the manufactory of Messrs. Bolton and Watt at Soho. Novel as was this mode of illumination, it did not attract the notice of the public until the year 1802, when the front of the Soho manufactory was lighted by Mr. Murdoch with a public display of gas-lights, on occasion of the national illumination in the spring of that year at the peace of Amiens. 42 GAS ILLUMINATION. The superiority of the new light over the dim oil- lights in use at that day excited no small degree of popular attention. An immense crowd came to view the spectacle, and an account of it was circu- lated throughout the country in the public papers. Gas-works were soon afterwards erected in Birming- ham, Manchester, Halifax, and other towns. In 1804 and 1805 the extensive cotton-mill of Messrs. Philips and Lee, at Manchester, was lighted with gas under the superintendence of Mr. Murdoch. In this establishment were nine hundred burners, pro- ducing a light equal to that of two thousand five hundred candles ; the quantity of gas made amounted on the average to twelve hundred and fifty cubic feet per hour. Mr. Murdoch sent a detailed account of his operations to the Eoyal Society in 1808, for which he received a gold medal. (An account of the application of gas from coal to economical purposes^ Phil. Trans. 1808, p. 124.) But although gas illumination was extensively adopted in manufactories, it made very little pro- gress in London, probably on account, in some mea- sure, of the insufficiency of the means then known of elTecting its purification. In manufactories, where the ventilation is generally good, the inconvenience arising from the disagreeable odour of impure gas was comparatively of little consequence; but in shops, private houses, churches, &c. the impurity of the gas would be a serious impediment to its general adoption. The indefatigable exertions, however, of Mr. Win- sor in London, at the same time that Mr. Murdoch HISTORY OF GAS ILLUMINATION. 43 was carrying on his operations in the country, were very efficient in introducing gas illumination into the metropolis. In 1803 and 1804 the Lyceum theatre, and soon afterwards one side of Pall Mall, were lighted by Mr. Winsor with coal-gas, the ma- nufacture of which soon suggested itself to the public as a lucrative speculation. In 1804 Mr. Winsor obtained a patent for some apparatus employed in the process, and established the National Light and Heat Company for carrying on the manufacture on an extensive scale. In 1809 this company applied to parliament for a charter, but they were opposed by Mr. Murdoch on the score of priority, and the charter was refused. On a subsequent application, however, the claims of Mr. Winsor were recognised, and the charter was granted. In the course of from ten to fifteen years the oil-lamps of every street and alley of the metropolis were displaced by gas, churches and other public buildings and shops were illuminated by the same light, and gas has now be- come general in almost every town in the empire. For many improvements in the construction of the apparatus, and in the practical details of the process, gas illumination is indebted to Mr. Samuel Clegg, whose attention was called to this subject so early as the year 1804, and who erected a gas-work of pretty large extent in the following year. Among the improvements introduced by Mr. Clegg may be mentioned the hydraulic main, by which the retorts are isolated while being emptied and charged ; the wet lime purifier, and the meter. During a parliamentary investigation, in 1823, it 44 GAS ILLUMINATION. was ascertained that the Chartered Gas Company (the original National Light and Heat Company) alone consumed annually at their three stations (Peter Street, Westminster ; Brick Lane, St. Luke's ; and Curtain Road, Shoreditch,) 20,678 chaldrons of coals, and produced on the average 680,000 cubic feet of gas every night. This quantity supplied more than thirty thousand burners, affording a light equal to as many pounds of tallow-candles. At the Peter Street station the number of retorts then erected amounted to three hundred, and of gasometers fifteen ; the extent of the main pipes belonging to this establishment for distributing the gas was fifty-seven miles. The number of retorts at the Brick Lane works in 1822 was three hundred and seventy-one, of which one hundred and thirty-three were worked on the average of summer and winter ; the number of gasometers was twelve, and the length of the distribution pipes forty miles. At the Curtain Road works the num- ber of retorts was two hundred and forty, but the greatest number worked in 1821 was eighty; the number of gasometers was six, and the length of the main twenty-five miles. At the same time three other large gas companies were in existence, namely, the City of London Gas- light Company, Dorset Street; the South London Gas-light and Coke Company, with two stations, one at Bankside and the other at Wellington Street ; and the Imperial Gas-light and Coke Company, whose establishment at Hackney was then in the course of erection. The extent of the entire operations of these companies was a little more than equal to that of the Chartered Company. HISTORY OF GAS ILLUMINATION. 45 Since the time at which the above estimates were made, several other companies have been established in London, and the amount of gas made in the vari- ous works has been increased at least seven-fold. The Chartered Company's works, which are supposed to supply about a fifth part of all the gas burned in London and the suburbs, consume no less than fifty thousand chaldrons of coals annually ; and, tak- ing the average product of purified gas from a chal- dron of coals at twelve thousand cubic feet, the amount annually made by the Chartered Company is six hundred millions of cubic feet, or, expressed by weight, more than eighteen million pounds. The gas-works next in extent to the Chartered Com- pany's is that of the London Gas-light Company, whose establishment at Vauxhall is, probably, the most complete in arrangement, and the most powerful of any in the world. The extent of their mains, which ramify into Middlesex as well as Surrey, ex- ceeds one hundred and fifty miles ; and, by the power of the works and the admirable mode in which the pipes are laid, gas may be supplied to a place more than seven miles distant, in the same quantity and with the same precision as at Vauxhall. The entire annual consumption of gas in London and the environs is estimated at not less than three thousand millions of cubic feet, and the light produced by the combustion may be considered as equal to what would be obtained from one hundred and sixty millions of pounds of tallow-candles. The annual consumption of coals in the various London gas-works is said to be about two hundred and fifty thousand 46 GAS ILLUMINATION. chaldrons, and nearly nine hundred tons per day are consumed in foggy weather in winter. Although the French tenaciously assert the claim of their countryman, Lebon, to the merit of having first applied gas as a source of light, yet this mode of illumination was not adopted in France until the year 1818, when M. Chabrol de Volvic, then prefect of the Seine, constructed, at the Hospital of Saint Louis at Paris, an apparatus which supplied gas to fifteen hundred burners. Since that time four other gas- works have been erected at Paris. The provincial French towns which possessed gas-works in 1839 were, Lyons, Reims, Amiens, Havre de Grace, and Elbeuf. Refuse oily matters are now common as sources of gas on the continent. Notwithstanding the present enormous production and consumption of gas, there can be no doubt that gas illumination is far from having attained that developement of which it is susceptible. Gas is still an article of increasing consumption ; and in propor- tion as attention is paid to improvements in its ma- nufacture, in the fittings, and in the mode of burn- ing, and to the means of conducting away the pro- ducts of the combustion, it will become more and more generally adopted in private dwellings, so as to supersede at last almost all other sources of artificial light. Before entering on the minute details of the process of making illuminating gases, it will be convenient to consider briefly, in the first place, the composition of different kinds of coal as the ordinary sources of COMPOSITION OF COAL. 47 gas, and, in the next place, the composition and pro- perties of those hydrocarbons which form the most important constituents of light-gas. § II. COMPOSITION OF COAL. The difference in the appearance of the several varieties of coal is not greater than the difference in their composition. The principal constituents of coal are carbon, hydrogen, oxygen, and nitrogen, the first three of which may be considered as the elements oi pure coal ; but it always contains likewise a great number of earthy impurities. The different kinds of coal comport themselves in the fire as ordinary or- ganic substances in which the combustible elements, carbon and hydrogen, are condensed into a very small volume. A very inferior coal contains a much larger proportion of carbon and hydrogen than wood. An insight into the composition of coal, sufficient to determine the relative value of the different varie- ties in most of their practical applications, may be obtained by determining, 1st, the quantity of volatile matters given off by the coal when heated to bright redness without access of air ; and, 2ndly, the propor- tions which exist between the carbon and the ash, or earthy matter, in the remaining coke, which may be ascertained by incineration in the open air. For gas illumination, the value of the coal is proportional to the quantity of volatile matters which it disengages at a red heat. The following are the results of exa- 48 GAS ILLUMINATION. minations of this kind on a few varieties of coal, by Mr. Mushet. Volatile Coke. Matter. '^Carbon. Ash. Scotch cannel coal 56-570 39-430 4-000 Derbyshire ditto 47-000 48-362 4-638 Welsh fumace coal 8-500 88-068 3-432 Welsh stone coal 8-000 89-700 2-300 Kilkenny coal 4-250 92-877 2-873 The most accurate method of determining the com- position of coal is by an ultimate analysis, after the manner of an ordinary organic analysis. The follow- ing table contains the results of ultimate analyses of several varieties of coal by different chemists : Carhon. Hydrogen. Oxygen. Nitrogen. 1. Caking coal 75-28 4-18 4-58 15-96 2. Splint coal 75-00 6-25 12-50 6-25 3. Cherry coal 74-45 12-40 2-93 10-22 4. Cannel coal 64-72 21-40 13-72 5. Ditto 72-22 3-93 21-05 2-08 6. Ditto 74-83 5-45 19-72 7, Ditto 70-90 4-30 24-80 8. Newcastle coal 84-99 3-23 11-78 The analyses Nos. 1, 2, 3, and 4 of this table are by Dr. Thomson ; No. 5, by Dr. Ure ; Nos. 6 and 8, by M. Karsten ; and No. 7, by Mr. Crum. As most, if not all kinds of coal, give, on distilla- tion, a larger or smaller proportion of ammoniacal products, the existence of nitrogen is probably con- stant, though not indicated by the analyses of Crum and Karsten. The quantity of that element, how- ever, may not exceed a mere trace in some kinds of coal. The proportion of nitrogen obtained by Dr. Thomson seems to be in very considerable excess. COMPOSITION OF COAL. 49. The composition of pure splint and cannel coal, according to analyses by Kichardson and Regnault, is represented by the formula C24 H13 0 ; which gives, when expressed in proportions per cent. Carbon 87-27 Hydrogen 7*88 Oxygen 4-85 100-00 Pure caking coal, according to Liebig, has the com- position C20 Hg 0, or, per cent., carbon, 87'59 ; hy- drogen, 6-57 ; and oxygen, 5 -84. Nitrogen does not seem to be an element of pure coal any more than of pure lignin or woody fibre, from which the coal itself is derived. The form in which the nitrogen exists is uncertain ; though given off as ammonia on the destructive distillation of the coal, it certainly does not pre-exist in that form, with the exception of a mere trace. It is probably derived, in part, from the albuminous matter contained in the original wood, but it may also be traced to the animal remains found in the coal. Some kinds of coal contain a small quantity of a resinous matter, which may be extracted by di- gesting the coal in ether, or oil of turpentine : the resin dissolves, and leaves the other constituents of the coal unacted on. Such coal is probably de- rived from the decomposition of trees which contain a considerable quantity of essential oil and resinous matter, such as the pine, for instance. The extraneous constituents of the commoner va- rieties of coal are the following : Argillaceous matter, derived from the contiguous E 50 GAS ILLUMINATION. beds, is the earthy impurity usually found in greatest quantity. It is composed chiefly of silica and alu- mina, but may also contain magnesia, oxide of iron, and potash; the latter is derived from the decom- position of felspar (see page 16). It is mixed so intimately with the coal as to be invisible by the naked eye, and can only be recognised (except by analysis) by the hardness and tenacity which it com- municates to the coal, especially when in a consider- able proportion. 'Carbonate of iron is very frequently, if not always, found in coal. It is not disseminated mi- nutely, like the argillaceous matter ; but, for the most part, in detached reniform masses of various sizes. Unfortunately for some applications of coal, and especially that of making gas, few varieties are free from iron pyrites^ or hisulphuret of iron. This mineral is generally visible by the naked eye ; it exists disseminated in minute crystals and in layers in fissures of the coal. The sulphuretted hydrogen contained in impure coal-gas is derived almost en- tirely from iron pyrites. Carbonate of lime is generally present in small quantity, sometimes minutely disseminated, like the argillaceous matter, but often in thick lamina. A constant product of the distillation of coal is muriate of ammonia^ which shews that chlorine must exist in the coal in some shape or other. Chlo- ride of sodium (common salt), which is contained in the water infiltrated into the coal-mines, may be the source of the chlorine; but muriate of ammonia itself has been detected by M. Bussy in a specimen of coal from Commentry, near MontluQon. A trace COMPOSITION OF COAL. 61 of hydriodate of ammonia was also found by M. Bussy. Sulphate of lime (gypsum) is considered by Lampadius to be a constant impurity in coal. Of all the specimens he examined, comprising more than thirty in number, not one was found to be free from that substance {Manuel de Metallurgie). Besides the impurities mentioned, coal has some- times been found to contain quartz, mica, sulphate of harytes, galena, blende, dolomite, phosphate of lime (in reniform masses, like carbonate of iron), sulphate of alumina, sulphate of iron, traces of manganese, magnesia, sulphur in the free state (M. Bussy), and a silicate of alumina of a peculiar composition (named pholerite by M. Guillemin). Silicate of soda has been detected in the water which infiltrated through coal-beds (Mr. Leigh). Spurious coal, (called, in Scotland, parrot coal,) which is found among strata of genuine coal, contains about one-fifth of its weight of stony matter. An- thracite leaves, when burned, nearly 40 per cent, of ash. So far as the use of coal in making gas is concerned, the impurity of greatest moment is iron pyrites — the principal source of sulphuretted hydro- gen. In the extensive purification required by the gas when the quantity of sulphuretted hydrogen is considerable, a notable proportion of useful gas, or vapour, is separated, together with the sulphu- retted hydrogen. Hence the advantage of ascer- taining, by analysis, the relative proportions of sul- phur in the different varieties of coal, in order to E 2 52 GAS ILLUMINATION. select that which contains the smallest quantity. It has been estimated that, from coal nearly free from sulphur, gas may be obtained which affords ten per cent, more light than that from the common sulphurous coal. It is not likely that any variety of coal would be found entirely free from a source of sulphuretted hydrogen, but the proportions of iron pyrites vary considerably in the different kinds. § III. HYDROCARBONS. The substances to which the illuminating power of coal-gas is due, are compounds of carbon and hydrogen, and are therefore termed hydrocarbons. These bodies constitute an extensive class of sub- stances, including solids, liquids, and gases, possess- ing, with a great diversity of physical characters, a remarkable similarity in composition. As a class, these bodies possess considerable interest on account of the useful applications which some of them have received in domestic economy, and of their produc- tion in various natural and artificial processes. These compounds have an organic origin, being either formed under the influence of a vital process, or de- rived from the decomposition of substances contain- ing carbon and hydrogen, which once formed part of an organized body. It is certainly a remarkable fact that bodies differ- ing from each other in appearance so greatly as es- sential oil of lemons, coal-gas, spirit of turpentine, naphtha or petroleum, bitumen, attar of roses, naph- thalin, and caoutchouc, should be composed of the same two elements, though united in different pro- HYDROCARBONS. 53 portions; but it lias been shewn that some of these hydrocarbons actually possess the same ultimate com- position, or proportions per cent, of the two elements, though unquestionably different substances. Essen- tial oil of lemons and oil of turpentine, for instance, are both composed of Carbon 88-2 Hydrogen 11-8 100-0 The term isomerism (from laog, equal, and |W/gfo?, part,) is made use of to express such a relation in composition between different bodies, and the bodies themselves are said to be isomeric. When the doc- trine of isomerism was first introduced, it was be- lieved that isomeric bodies may have not only the same ultimate composition, but the same constitution (see page 31), or the same arrangement of the ulti- mate atoms. But more recent research has been un- favourable to such a view, and the term isomerism is now very commonly and generally employed to indicate identity in the composition of two or more bodies when expressed in one hundred parts, not necessarily accompanied by a similar arrangement, or number of the ultimate atoms. In the example above cited, the proportion per cent, of carbon and hydrogen shews the relative proportion of the equi- valents to be five equivalents of carbon to four equi- valents of hydrogen. Now, a closer investigation of the essence of lemons has led to the conclusion that one integrant molecule, or equivalent of thxit essence, contains ten equivalents of carbon and eight equiva- lents of hydrogen ; while the molecule of oil of tur- 54 GAS ILLUMINATION. pentine is believed to contain twenty equivalents of carbon and sixteen equivalents of hydrogen. Where such difference in constitution exists, the possession of the same ultimate composition need not be neces- sarily accompanied by the possession of identical pro- perties. Several gases and vapours among the hydrocarbons are found to possess exactly the same composition, taking equal weights; but, in equal volumes^ the amount of carbon and hydrogen in the gases, or vapours, is found to be very different, and in mul- tiple proportions, defiant gas, for example, has exactly the same composition as a gas obtained by the destructive distillation of oil, taking equal weights ; but in equal bulks there is found exactly twice as much matter in the latter as in the former. The composition of defiant gas is expressed by the for- mula C4 H4, and that of oil-gas by Cg Hg. As re- gards their composition, therefore, these gases differ from each other only in their state of condensation. The hydrocarbons on which the illuminating power of coal-gas depends are light carhuretted hydrogen and olefiant gas. Light carhuretted hydrogen. — This gas consists, in 100 parts by weight, of 75 of carbon and 25 of hydrogen, proportions which correspond to one equi- valent of carbon and two equivalents of hydrogen. Its density is 560'45, compared with air as 1000; and in one volume of it are contained two volumes of hydrogen gas and one volume of carbon vapour. It is colourless, tasteless, quite neutral, and nearly iuodo- HYDROCARBONS. 55 rous. It is unable to support tlie respiration of ani- mals, but is respirable if mixed with air. If a burn- ing taper is introduced into a jar of the gas, the flame of the taper is extinguished ; but the gas itself takes fire when in contact with air, and burns with a yellow flame of little intensity. Mixed with a proper propor- tion of atmospheric air or oxygen, light carburetted hydrogen forms a mixture which explodes violently by the contact of flame, or by the electric spark. It re- quires twice its bulk of oxygen for complete combus- tion, and affords water and its own bulk of carbonic acid. It is a compound of considerable stability; is not affected by chlorine gas in the direct rays of the sun, if all moisture is absent; and is only partially resolved into its elements when passed through a tube heated to whiteness. A small quantity of carbon is then deposited within the tube. Light carburetted hydrogen is a product of the destructive distillation of most organic matters, but it cannot be prepared in a state of purity by such a process. It is a constant product of the putrefac- tive decomposition of vegetable matter under the sur- face of water, and may be readily obtained by agitat- ing the mud at the bottom of stagnant pools and col- lecting the gas as it bubbles up in an inverted bottle and funnel. It is hence sometimes termed the in- flammable air of marshes, or marsh gas. As thus ob- tained, it contains carbonic acid gas, and a small pro- portion of nitrogen gas. The former may be re- moved by agitating a little solution of potash in the gas, but no easy method is known of separating the nitrogen. The best mode of preparing pure light carburetted 56 GAS ILLUMINATION. hydrogen artificially is, by distilling a mixture of acetate of potash with an alkali at a red heat, in a coated glass or an earthen retort. The gaseous mix- ture which is obtained on passing the vapour of alco- hol through an ignited porcelain tube consists chiefly of this gas. Although light carburetted hydrogen is instantly kindled by flame if in contact with the air, yet it re- quires a higher temperature for its inflammation than most other combustible gases. A glass rod, heated to dull redness, is sufficiently hot to ignite hydi'ogen, sulphuretted hydrogen, carbonic oxide, and olefiant gases ; but requires to be heated to bright redness, or whiteness, to set fire to light carburetted hydrogen. Olefiant gas. — Like light carburetted hydrogen, olefiant gas has not yet been reduced to the solid or liquid state. This gas exists ready-formed in na- ture, and may be produced artificially by the destruc- tive distillation of fatty, oily, and bituminous mat- ters, and, in fact, the most part of organic substances. It was first recognised as a peculiar body in 1796, by the associated Dutch chemists Bondt, Dieman, Van Troostwick, and Lawerenburg, who gave it its present name from its property of forming an oily- looking compound with chlorine. • This gas is commonly obtained by heating together in a retort a mixture of one part of alcohol with six or seven parts, by weight, of oil of vitriol. The re- tort should be furnished with a globular receiver, from which an exit-tube leads into the pneumatic trough where the gas is to be collected. The gas which is given off" is a mixture of equal volumes of HYDROCARBONS. 57 olefiaiit gas and sulphurous acid, and contains, be- sides, vapours- of water, ether and alcohol. It may- be obtained pure by passing it first through milk of lime to retain the sulphurous acid, and afterwards through oil of vitriol to absorb the vapours. Olefiant gas is a little lighter than air, its specific gravity being 996"87, compared with air as 1000. It is tasteless, but has a peculiar feeble ethereal odour. Like light carburetted hydrogen, it cannot support respiration or combustion. It inflames at a red heat when in contact with the air, and burns with a white and remarkably luminous flame. If mixed with air and exploded, the detonation is extremely violent. Olefiant gas consists, by weight, in 100 parts, of Carbon 85-71 Hydrogen 14-29 100-00 or, by volume, of two volumes of carbon vapour and two volumes of hydrogen gas condensed into one vo- lume. Its symbol is C4II4. The peculiar luminosity of the flame of this gas, and the force of its explosion when mixed with air or oxygen, are clearly accounted for in its state of condensation. Olefiant gas requires three times its volume of oxy- gen for complete combustion, and produces water and two volumes of carbonic acid gas. When exposed to a red heat, as by being passed and repassed through a porcelain tube, it is decomposed into its elements, solid carbon being deposited within the tube, and hy- drogen gas liberated, having twice the original volume of the olefiant gas. If a mixture of one volume of ole- fiant gas with two volumes of chlorine gas contained in a tall and narrow glass jar is inflamed by contact 58 GAS ILLUMINATION. with a lighted taper, the olefiant gas is decomposed, and combustion takes place in a very striking man- ner : a deep red flame gradually descends through the mixture, resulting from the combination of the chlo- rine with the hydrogen of the olefiant gas, by which muriatic acid is produced, while the carbon is at the same time deposited as a dense black cloud. If ole- fiant gas and chlorine gas are merely mixed in equal volumes in a glass jar over water, the two gases gra- dually combine, and condense into an oily-looking li- quid known as oil of olefiant gas, or Dutch liquid. Olefiant gas also unites with iodine, and with bro- mine. The combination with iodine is a white crystalline solid, which may be sublimed without decomposition in an atmosphere of olefiant gas, but not in the air. The inflammable gas which escapes from fissures in the earth, before referred to (page 38), known as fire-damp^ is essentially a mixture of light carbu- retted hydrogen, free hydrogen, and olefiant gas, differing little in properties and composition from purified coal-gas. It generally proceeds from sub- terranean deposits of coal, and is found in the work- ing of coal-mines pent up in cavities. It seems to be given off" spontaneously from the fresh surface of some kinds of coal in smaU but sensible quantities. When the gas accumulates in the gallery of a coal-mine where the air is still, so as to form one-seventh or one-eighth part of the atmosphere, the approach of a naked flame instantly causes the mixture to ignite with a most tremendous explosion, by which, before the introduction of the safety-lamp of Sir Humphrey Davy, the life of the coal-miner was placed in the most imminent danger. HYDROCARBONS. 59 An explosive mixture of fire-damp and air is not ignited by iron or charcoal at an incipient red heat, although the contact of flame of any kind instantly determines its inflammation. On this circumstance depends the efficacy of the safety-lamp, which is sim- ply a common oil lamp with a chimney of wire gauze, so constracted that all the air which obtains access to the flame is obliged to pass through the gauze. The cooling power of gauze containing about eight hundred apertures in a square inch is sufficient to prevent, under ordinary circumstances, the passage of flame from the interior to the exterior of the lamp. A mixture of fire-damp and air does not explode vio- lently when the quantity of air is much above or below that required for the complete combustion of the gas, which is about seven or eight times its vo- lume. If fire-damp consisted only of light carbu- retted hydrogen, it should require very nearly ten times its volume of air. A mixture of one volume of light carburetted hydrogen and four of air does not explode, nor does a mixture of one volume of gas and fifteen of air; in the latter case the gas burns about the flame of the taper, but the large quantity of air prevents the temperature of the mixture rising sufficiently high for ignition. Naphthalin and Paranaphthalin. — Light carbu- retted hydrogen and olefiant gas are the only hydro- carbons which are present in considerable quantity in coal-^«s, but the volatile solid and liquid products of the distillation of coal also contain several hydro- carbons, one of the most important of which is naph- thalin. This substance is a white crystalline solid. 60 GAS ILLUMINATION. sometimes found condensed in certain parts of the coal-gas apparatus in a tolerably pure state, but is most abundantly contained in the tar. It may be obtained by subjecting coal-tar to distillation, the receiver being changed at different periods of the process. ^The first product which distils over is a yellowish oily-looking liquid known as coal-oil, which is a mixture of several distinct substances, some of which are acids and some bases, but little is Imown respecting their composition. If coal-oil is redistilled and the last products received apart, they afford a considerable quantity of naphthalin when cooled arti- ficially. The naphthalin thus obtained may be purified by solution in hot alcohol and recrystallization. It is stated by M. Laurent that this substance is obtained more abundantly from old than from recent coal-tar, and also that the product is much increased if the coal-oil is subjected for some time to a current of chlorine gas. When pure, naphthalin has the form of tr^insparent, colourless and shining plates, possessed of a peculiar odour and a burning taste. It fuses at about 176" Fahr., boils at 423° Fahr., and may be condensed without change. It is insoluble in water, but very soluble in alcohol and ether, and is precipitated in a crystalline state from its solutions in these liquids on the addition of water. Naphthalin is readily in- flamed, and burns with a strong light and produc- tion of much smoke. It is not decomposed by heat into free carbon and hydrogen so readily as most other hydrocarbons, and seems, in fact, to be pecu- liarly the product of a high temperature; it being produced when wood and most vegetable matters are HYDROCARBONS. 61 exposed to the destructive distillation at a bright red heat, but not in so large a proportion at a lower tem- perature. The composition of naphthalin is the fol- lowing : Atomic weight. Per-centage composition. 20 eq. carbon ... 120 93-75 8 eq. hydrogen ... 8 6-25 1 eq. naphthalin ... 128 100-00 With the assistance of heat, naphthalin combines with oil of vitriol and with anhydrous sulphuric acid, forming a fine deep purple-red liquid. When this liquid is diluted with water, a considerable propor- tion of the naphthalin is precipitated in an altered state, and the aqueous solution contains three peculiar combinations of naphthalin (or modifications of that substance) with hyposulphuric acid (Sa O5), each of which possesses the properties of an acid. A great number of interesting compounds have also been ob- tained by the action of chlorine and nitric acid on naphthalin, a short account of which may be found in the last edition of the " Elements of Chemistry ". of the late Dr. Turner, and in the " Elements of Chemistry " of Professor Graham. The name of paranaphthalin has been applied by M. Dumas to a hydrocarbon much resembling naphthalin in appearance, which substance it accom- panies in coal-tar. It has the same ultimate compo- sition as naphthalin, but its constitution is considered to be different, its symbol being C30 H12, instead of C20 Hg. Several circumstances serve to distinguish paranaphthalin from naphthalin. The former is in- 62 GAS ILLUMINATION. soluble in hot alcohol; it fuses at 356° Falir., and boils at 572° or higher. If equal weights of para- naphthalin and naphthalin are converted into vapour at the same temperature, it is found that the va- pour of paranaphthalin occupies exactly one-third less space than the vapour of naphthalin. The den- sity of the vapour of paranaphthalin is 6630 (air at the same temperature being 1000) ; the density of the vapour of naphthalin is 4420, or exactly one- third less. Some other hydrocarbons are given off in small quantity on the destructive distillation of coal, but their composition and properties are not well known. They are mostly liquids, and contained in the tar. A few ternary combinations of carbon, hydrogen, and oxygen, (the last element in small relative propor- tion,) are also produced in small quantity, some of which are also contained in the tar obtained by the destructive distillation of wood. As the remaining secondary products obtained in the making of coal- gas are not peculiar to that process, a separate de~ scription of them here is unnecessary. We proceed, therefore, in the next place, to the process itself. § IV. PROCESS OF MAKING COAL-GAS. By reverting to the introductory observations at page 36, it will be observed that a coal-gas appa- ratus must be so constructed as not only to generate but purify the gas : it must also have the means of discharging the gas steadily into the pipes for dis- tribution, in order to ensure an uniform exit from PROCESS OF MAKING COAL-GAS. 63 the burners. The principal parts of the apparatus are the retort, hydraulic main, cooler, purifier, and gasometer. The design on the following page shews the arrangement of the apparatus when looking at the front of the furnace, or the anterior ends of the retorts : — a is the furnace, with a set of five retorts, from each of which a tube proceeds upwards per- pendicularly to a height of from ten to twelve feet ; it then takes a curve downwards, and enters the hydraulic main h. The latter is an iron tube of from twelve to fourteen inches in diameter, placed horizontally: the extremities of the tubes from the retorts dip about two inches below the surface of the liquid in the hydraulic main. From one end of this tube, a little above the centre, proceeds the tube c, into a close cistern c?, in which the tar and ammoniacal liquor are received and separated. From the top of the opposite end of the hydraulic main proceeds the tube by which the gas is conducted into the cooler and having deposited here a further quantity of condensable matter, the gas is passed on to the lime purifier and from thence, commonly, to the gasometer ^, but sometimes through other apparatus, not represented in the annexed figure, but which will be described afterwards. The con- struction of each of the parts of a coal-gas apparatus admits of certain modifications, and requires to be considered minutely. The tabular view of the products of the distillation of coal in the page following the figure will assist in shewing the uses of certain parts of the apparatus. GAS ILLUMINATION. 66 GAS ILLUMINATION. u LJ 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 the side. Such a retort Fig. 2. Fig. 3, is vcry readily charged, and the gas produced from it is of good quality ; but its form is very inconvenient for the removal of the coke at the end of the process. One of the means de- vised in order to remedy this defect was 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 apertures 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 afterwards used, capable of holding from ten to fifteen hundred- weight of coal, from which the coke was easily re- Fig. 4. moved by an iron basket or grap- pler (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 re- moved by a crane. The great disad- vantage of this retort is, that the heat requires a considerable time to pene- trate 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 PROCESS OF MAKING COAL-GAS. 67 retort, for reasons which will afterwards appear. To the latter it was found expedient to return, and the inconvenience experienced in the removal of the coke was lessened by placing the retort in^ hori- zontal 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 shewn in vertical sections, parallel to the door, at figs. 5, 6, and 7 ; fig. 5 is called the D or semicir- cular retort, fig. 6 the kidney-shaped retort, and fig. 7 the elliptical retort. The greatest breadth of ^' ^' each form is about twen- ty 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, un- less 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 employed. 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 * The circular retort of ten or eleven inches in diameter is preferred at the Manchester gas-works, where cannel coal only is employed. F 2 68 GAS ILLUMINATION. Fio;. 8. and hold-fast screw, as shewn in fig. 8, and rendered air-tight by a luting, for which purpose the refuse lime from the purifier is found very convenient. Three, five, or seven retorts are arranged in one fur- nace or " bed," according to the extent of the works. Each retort has what is called a mouth-piece ^, fig. 8, projecting from the front of the brickwork, from which rises the up- right tube leading into the hydraulic main. The dia- meter of this tube is three or four inches, its height to the bend from ten to fourteen feet, and the dis- tance of the hydraulic main from the bend from three to four feet. The bend is commonly made by a plain curve, but some- times 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 sufficient to prevent the liquor being driven into the retort by the pressure on the gas in the lime purifier fig. 1, page 64. 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, PROCESS OF MAKING COAL-GAS. 69 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 different fur- naces meeting in a central chimney. As coke is the fuel generally employed to heat the retorts, little or no smoke is given off. In a well-conducted establish- ment, two men are sufficient for the management of three furnaces of five retorts each ; but, as the retorts are kept in constant work throughout the twenty-four hours, relays of men are required for the night-work. By the decomposition of the defiant gas and va- pours of hydrocarbons at a high temperature (page 57), the interior of the retorts becomes lined with a dense carbonaceous deposit, which, by its imperfect conducting power, offers an impediment to the trans- mission of heat. A patent Avas 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 opera- tion. 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 extre- mity, 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 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 mis- 70 GAS ILLUMINATION. cible ; and the former, being the heaviest, is found at the bottom of the cistern, from whence it may be with- drawn by the cock i. Although a very large quantity of tar and ammoni- acal 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 vapour, which must be removed before it enters the lime purifier. To effect their separation, the tempe- rature of the gas is reduced by passing it through the cooler or condenser fig. 1). Figs. 9 and 10 represent a convenient and effective condenser, which was invented and patented by Mr. Fi^. 9. Fig. 10. 1^ 1^ r:^\ 1^3 CZ3CI3CZ3 C=3C=3C=3 John Perks, in 1817. It consists of a series of four- inch tubes, arranged in a rectangular iron chest, double-bottomed and open at top. The dimensions 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 the tubes are open, and terminate in the plate a, between which and the true bottom are placed partitions, to separate the ex- tremity b from the extremity c, b' from c, b" from c\ &c. ; but these partitions do not quite extend to the PROCESS OF MAKING COAL-GAS. 71 true bottom. The tubes are severally connected at top, either by a curved tube or a saddle-joint, so as to form, with the partitions at bottom, one continuous tube. The appearance of the top of the tank is shewn 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 tube of a length of 432 feet. Cold water is poured into the cooler by the funnel-tube 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 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 by mere exposure to the air. The condenser represented in fig. 1, page 64, 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 operation, consists of an iron rectangular vessel about nine feet long, five feet wide, and four feet deep, containing several horizontal par- titions or shelves of cast-iron plates, which have edges of about three inches in height, for the purpose of holding water. These shelves are all fastened to the sides and, alternately, 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 and 72 GAS ILLUMINATION. 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 cyanogen), and some ammonia. (See table, page 65.) 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 odour if it escapes into the atmosphere unburned, is highly poisonous, and pro- duces by its combustion sulphurous acid, which, by the action of the oxygen of the air and moisture, passes into the state of sulphuric 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 ac- tion of some substance for which 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 Manchester in 1808, but was not used generally on the large scale until several years afterwards. Lime not only absorbs sulphuretted hydrogen, but also carbonic acid and a little hydrocyanic acid, forming, respectively, sulphuret of calcium (hydro- sulphate of lime), carbonate of lime, and cyanide of calcium. The principal methods employed to get rid of sulphuretted hydrogen, previous to the introduction of lime, were, passing the gas through hot iron pipes PROCESS OF MAKING COAL-GAS. 73 and through a large quantity of water ; but such me- thods 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 2ndly, 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 extremity into a cone and flat disc, and the latter is pierced with a great number of very small apertures : Ms 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 stuffing-box at the top of the purifier, and is turned by wheel and pinion work. In 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 />, and withdrawn 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 only 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 74 GAS ILLUMINATION. the third higher than the second. By this arrange- ment 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 con- ducted by a discharge-tube, or waste-pipe, into the second purifier on a lower level, from whence the liquid is conducted into the first purifier. From the latter it is let ofi" 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 portions of gas in the vessels above; in the second vessel it meets a purer liquor; and, almost purified itself, passes from thence into the third vessel, where it meets lime fresh from the cistern above. A more efiectual method of obtaining the complete absorption of the condensable gases could hardly be devised. When the gas is arrived at the last purifier, to as- certain if all the sulphuretted 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 sulphuret- ted 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 sub- acetate 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 PROCESS OF MAKING COAL-GAS. 75 by the coloration of the card. It is necessary that the card should be moist in this experiment, as some salts of lead thoroughly dry are not affected by sul- phuretted 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 aque- ous solution 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. Eeuben Phillips of Exeter, the gas is introduced 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 upwards through several layers of lime, placed on iron gratings 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 sufiiciently 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 water-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 76 GAS ILLUMINATION. very convenient in small works, but is too bulky when adapted to large establishments. Mr. Malam, however, patented, in 1822, an effective purifier for the use of extensive gas-works, on the same 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 increased; but it has a great advantage in requiring no constant mechanical power. In the wet purifier a bushel of lime is suffi- cient to purify, on the average, about twelve thousand cubic feet of gas. The spoiled and foetid lime was formerly allowed to run to waste, to the great annoyance of the neigh- bourhood ; it is now preserved and employed as ma- nure, and also as a cement to lute the covers of the retorts. The foetid liquor which is drained from the lime obtained in the wet-lime purifier, is thrown into the ash-pits of the furnaces, where it evaporates, its vapour passing through the fire and up the chimney. By keeping the bars of the furnace cool, the va- pour tends materially to their preservation. The gasometer^ 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, according to the extent of the works. It is considered that a capacity of thirty thousand cubic feet is the largest dimensions which PROCESS OF MAKING COAL-GAS. 77 can be given to a gasometer with advantage, as the sheet-iron of which it is formed must then be in- conveniently thick, and very strong internal cross- bars would be required to strengthen the hollow cy- linder. The cistern, or exterior tank, is commonly made of plates of cast-iron, but sometimes of ma- sonry, made tight with hydraulic mortar. In some gas-works the whole cistern is sunk in the ground. The gas-holder may be supported within the cistern by means of a chain connected with rods, which are attached to the top of the gas-holder : the chain runs over two pulleys, o and o', and bears a counterpoise, j9, 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 circum- ference. The tube which conducts the gas from the lime purifier to the gasometer and the tube 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 w, 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 q 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 gas- 78 GAS ILLUMINATION. ometers in large works, some being filled while others are being emptied.* According to the hydrostatic law, that the 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 water 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 counter- poise. 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 contriv- ances by which a greater bulk of gas may be collected 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 cy- linders of unequal diameter and concentric. The * At the Westminster station of the Chartered Gas Company there are no less than twenty-one gasometers, each containing on the average thirty thousand cubic feet. PROCESS OF MAKING COAL-GAS. 79 Fi^. 11. [ill bottoms and tops of the cylinders are provided with flanges curved in opposite directions, the flange turning inwards and upwards at bottom, and outwards and down- wards at top. The outermost cy- linder is covered at top, but all the others are open both at top and bottom. Supposing the cy- linders to be sunk in the cistern and ready to receive gas, the out- ermost first rises on the admis- sion 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 pre- vents 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 principle of the construction is obviously the same. The telescope gasometers are usually sus- pended at three points on their circumference, by three chains running over pulleys afiixed to three pillars. The numerous substances given off" from coal when that body is subjected to the destructive distillation (mentioned in the table at page 65), are not afforded in the same relative proportions at the same periods of the distillation. On the first application of heat to 80 GAS ILLUMINATION. coals in a retort, steam comes off, together with the air of the retort. As the heat approaches redness, a considerable quantity of tar is disengaged, but only a small proportion of gas below a red heat ; and what gas is produced at that temperature possesses very feeble illuminating power. When the retort has at- tained a bright red heat, the evolution of gas is at its maximum ; but tar is still produced, though in smaller quantity than at a lower temperature. At a white heat, and after the operation has been carried on for two hours, the proportion of tar is very small; that of the gas is still large, but decreasing. At length the evolution of gas ceases completely, whatever de- gree of heat is applied. The difference in the bulk of the gas given olF from coal at different periods of the process is shewn in the following table, by Mr. Peckston, of the gas obtained from a chaldron of Newcastle coal distributed into eighteen retorts. The coal was heated to bright red- ness immediately. Cubic fee In the first hour . . 2000 In the second hour . 1495 In the third hour . 1387 In the fourth hour 1279 In the fifth hour . 1189 In the sixth hour 991 In the seventh hour . 884 In the eighth hour 775 In eight hours . 10,000 The composition and illuminating power of the gas produced at different periods of the process vary con- siderably. The gas evolved before the retort attains a red heat contains a considerable amount of carbonic PROCESS OF MAKING COAL-GAS. 81 oxide; hence its feeble illuminating power. That produced at a bright red heat contains a larger pro- portion of olefiant gas and vapours of hydrocarbons than what is formed at any higher or lower tem- perature. As the distillation advances, the tem- perature being somewhat increased, the proportion of illuminating gases decreases considerably, while that of carbonic oxide and hydrogen increases in proportion. The density of the gas also, which is to a certain extent proportional to its illuminating power, gradually decreases with the duration of the process and the increase of the temperature. The following tabular view of results of the examination, by Dr. Henry, of the gas evolved from cannel coal at different periods of the process, will shew more clearly the difference in the composition. COMPOSITION OF COAL-GAS IN 100 VOLUMES. 1. 2. 3, 4. 5. Olefiant gas and vapours 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 6-3 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 675 527 533 450 345 Nos. 1, 2, and 3 of the preceding table were pro- G 82 GAS ILLUMINATION. duced 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 introduced ; a portion of the tar, which would otherwise distil over into the hydraulic main, is thereby converted into ex- cellent 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 of the mass. The advantage in the use of the D-shaped, kidney-shaped, and ellip- tical retorts, over the circular or cylindrical (page 67), is wholly referable to the circumstance, that the coal is more rapidly heated in the former than in the lat- ter, 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 9000 cubic feet; in the circular retort, the diameter of which is about the same as the widest diameter of the other construction, the average quantity from the same kind of coal, at the same degree of heat, and worked in the same man- ner, is 6400 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 required with circular retorts. Five PROCESS OF MAKING COAL-GAS. 83 of the former, worked with 120 pounds of coal to each, during a four-hours' charge, will produce, in twenty-four hours, as much 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-lightings p. 126, 3d edit.) The form of retort said to be best adapted for the rapid decomposition of the coal is the '•'rotary re- tort;' patented by Mr. Clegg in 1816, but its ex- pensiveness has hitherto proved an obstacle to its general introduction. It 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 insufiicient 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 placed (by five at a time) for two hours at the part heated to redness. The gas ob- tained 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 olf in twenty -four hours. During the whole process, the temperature of the retort should not exceed that of a bright red heat. At a higher temperature, the proportion of hydrogen, carbonic oxide, and nitrogen gases is greatly increased ; while the production of olefiant gas, the chief illumi- nating ingredient, almost ceases. This arises from the decomposition of the olefiant gas at a high tempe- G 2 84 GAS ILLUMINATION. rature into free hydrogen or light carburetted hy- drogen and carbon ; the latter is deposited in a solid state around the sides of the retort in a pe- culiar form, known as gas-carbon. The carbonic oxide gas (CO or C2O2) is derived from the com- bination of carbonic acid gas (CO2) with carbon; one equivalent of carbonic acid giving rise to two equivalents of carbonic oxide, by uniting with one of carbon. The nitrogen is probably derived im- mediately from the decomposition of ammonia into its elementary constituents, hydrogen and nitrogen. 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 decomposi- tion. Hence the disadvantages of increasing the temperature beyond that of bright redness. As ni- trogen and carbonic oxide gases are always disengaged in abundance at the end, in the ordinary manner of conducting the process, if gas of a very superior qua- lity 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 distillation. The selection of a proper kind of coal for making gas is a subject which seems to deserve more atten- tion 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 PROCESS OF MAKING COAL-GAS. 85 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 carbu- retted gas, and give as brilliant a light in smaller quantity, without the production of so much heat as is developed in the combustion of the highly hydro- genated gas derived from the commoner kinds of coal. In such case, the price of the gas per meter might reasonably be increased. Less labour 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 shews the quantity of gas ob- tained on the large scale from several different kinds of coal in elliptical retorts at a bright cherry-red heat by daylight, the charge to each retort being about 126 pounds of 2 o « ^ ta g " S " l/J o o o o o Tj ^ as 2 " § o 3 .S „ o 5 o U A p. u Oi -g^-Sl-sl 1^ s P- « "> " ^lilii. «, S M "a ooo«o^co>oooo J? old „ 40 }f 5> young white beech-wood ( wei ssbuchenholz) 32 )> old „ 35 » young alder- wood 35 » }> old „ 40 5) young birch-wood 25 )) old „ 30 if young red pine (fichtenholz) 15 J5 old „ 15 » J5 young white pine (tannenholz) 22-5 7) old „ 25 young pitch pine (kiefernholz) 12 old „ 15 The diflfereBce in the composition of the ash de- rived from the wood of different kinds of trees is not very considerable. The portion soluble in water com- prises from one-eighth to one-fourth of the entire ash. Analyses of the insoluble portions of the ashes of oak- wood and beech-wood afforded the following results (M. Berthier) : From oak- From beech- wood. wood. Lime, as carbonate and phosphate . . 53-2 42-6 Magnesia ..... 7-0 Oxide of iron . . . . . 1-5 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 6-4 5-8 100-0 100-0 The soluble portions of the same ashes were found to be composed of NATURE AND CAUSES OF THE DECAY OF WOOD. 175 From oak- From beech- Potash and soda Carbonic acid Sulphuric acid Muriatic acid Silica wood. 65-2 24-3 10-0 wood. 64-1 22-4 7-3 5-2 1-0 •5 100-0 100-0 § II. 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, according to the analyses of MM. Gay-Lussac and Thenard, and Dr. Prout, 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 ordinary state, from three to five per cent, of soluble matter, of which nitrogen forms an essential constituent. It appears from the experiments of De Saussure that the decay of woody 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 separation of a portion of the carbon of the wood by a process of oxidation or combustion at low temperatures. Such cases of slow oxidation have been distinguished by Liebig by the name of eremacausis, which is compounded from ^gjO/a, by degrees, and Kuvffig, burning. 176 PRESERVATION OF WOOD. But the examination of the products of the action of oxygen on dry wood, and the analysis of the re- siduary mould or humus, shew that wood loses by the process of slow combustion or eremacausis, be- sides carbon, a certain amount of its hydrogen and oxygen in the proportion to form water. On exposing 240 parts of dry saw-dust of oak-wood to the action of oxygen gas, De Saussure found that the oxygen be- came converted into the same volume of carbonic acid gas, containing 3 parts by weight of carbon. But the wood diminished in weight by 15 parts ; 12 other parts were therefore separated in the form of oxygen and hydrogen. For the following considerations on the nature of the decay of woody fibre, I am indebted to Professor Liebig's valuable work entitled " Organic Chemistry applied to Agriculture and Physiology." In an agri- cultural point of view this process of decay is of great importance, as being the means of furnishing the soil with humus ; which, by the action of the air, becomes a means of supplying the roots of plants with carbonic acid. Notwithstanding the separation of carbon from wood during the process of decay, in 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 proportion of carbon in the . different products augments as the decay advances. The weight of the hydrogen and oxygen therefore, which are given off simultaneously with the carbon, is greater than the weight of the separated carbon. According to Gay-Lussac and Thenard, 100 parts of NATURE AND CAUSES OF THE DECAY OF WOOD. 177 oak-wood dried at 212°, from which all soluble matters had been separated bj means of water and alcohol, contained 5 1*45 parts of carbon ; the remainder being hydrogen and oxygen in the same proportion as in water. A specimen of mouldered oak-wood, taken from the interior of the trunk, of a chocolate-brown colour and retaining the structure of wood, was found by M. Meyer to contain 5 3 '3 6 per cent, of carbon, and 46 '44 per cent, of hydrogen and oxygen, in the same proportions as exist in water. Another specimen of mouldered oak-wood, in a more ad- vanced state of decay, of a light brown colour and easily reducible to fine powder, was found by Dr. Will to contain 56*2 per cent, of carbon, and 43*8 of hydrogen and oxygen in the usual proportions. The composition of these substances in equivalents is represented by the following formulee, with which the percentage composition, as obtained by analysis, closely agrees. Fresh oak-wood, by Gay-Lussac and Thenard Cgg H^j O^^ Humus from oak, by M. Meyer . . • Hj„ O.^^ Humus from oak, by Dr. Will . . . Cj^ H,g 0,g It appears from these data that, for each equivalent of carbon separated from the wood, there are also sepa- rated two equivalents of oxygen and two equivalents of hydrogen. The process is merely a case of slow com- bustion through the oxygen of the air, but it remains to be decided whether 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 more intimately than be- fore with the oxygen of the wood. If, as some sup- pose, the hydrogen and oxygen of the wood already N 178 PRESERVATION OF WOOD. 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 favour 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 like- wise be considered as hydrates of carbon. And, if the hydrogen does not exist in woody fibre in the form of water, the direct oxidation of the carbon cannot be considered as at all probable without re- jecting all the facts established by experiment regard- ing the process of combustion at low temperatures. (Liebig, Agricultural Chemistry, p. 295, 3rd edit.) 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 expense 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, favoured with warmth and light, but certainly not so far as to the entire separation of the hydrogen and oxygen ; for, with the 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 sufiers when ex- posed in a humid state to an unlimited quantity of air. But when the air is entirely or partially ex- NATURE AND CAUSES OF THE DECAY OF WOOD. 179 eluded, water still having access, the order of decom- position is considerably modified. Carbonic acid is then evolved in the same manner as when air is freely admitted, but the hydrogen of the wood re- mains 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 .... 45-31 44-43 Aslies . . . . 1-27 1-37 100-00 100-00 The mean of these numbers corresponds very nearly to the formula C33 H27 O24, which gives, by calculation, carbon 47*9, hydrogen 6*1, oxygen 46. By comparing 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 so- lution 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 car- bonic acid. The above formula for mouldered oak is obtained by adding to the formula for pure woody fibre the elements of five equivalents of water, and three equi- valents of oxygen, and subtracting therefrom three equivalents of carbonic acid. N 2 180 PRESERVATION OF WOOD. Woody fibre • ^36 H22 O23 5 eq. water . 0. 3 eq. oxygen 0, ^36 H„ Deduct 3 eq. carb. acid C3 Mouldered oak . ■ ^^33 H27 024 But the composition of mouldered wood varies ac- cording to tlie facility with which oxygen has access, A specimen of white mouldered beech- wood afforded, on analysis, carbon 47*67, hydrogen 5'67, and oxygen 46*68, numbers which correspond to the formula C33 O24 (Liebig). The decomposition which wood suffers in marshy soils, and under water in contact with decaying vege- table 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 cir- cumstance 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 hy- drogen 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 at- tenuated 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 light NATURE AND CAUSES OF THE DECAY OF WOOD. 181 carburetted hydrogen or marsh gas (CHg), 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 thou- sands 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 hody already under- going a similar change. When fresh wood is placed in contact with decaying wood, or other decaying ve- getable 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 yeast causes a transformation of the elements of sugar. The result diifers according to the composition of the substance 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 fermentation and oxidation, by which alcohol is converted into acetic acid. By absorbing oxygen, the alcohol becomes entirely converted into water and acetic acid. But pure alcohol, whether strong or diluted with water, may be exposed to free oxygen without the formation of the smallest particle 182 PRESERVATION OF WOOD. of acetic acid, or alteration of any kind ; as also may pure woody fibre without formation of humus. One of the conditions necessary to the conversion of alcohol into acetic acid is contact with a nitrogenized body, as yeast, in a state of slow oxidation or pu- trefaction; a condition precisely similar to that under which the decomposition 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 transformation 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 im- part its own motion to another molecule with which it may be in contact." The albuminous matter which wood contains dis- tributed over the cellular tissue is intimately con- nected with the decomposition of the wood. It is a nitrogenized substance, and identical in composition with animal albumen ; like which body, it is putres- cible 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 che- mical action going on at the same time, from the in- creased facility for the introduction of air and water to the interior 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, NATURE AND CAUSES OF THE DECAY OF WOOD. 183 carburetted hydrogen, and water. The influence of ammoniacal salts in favouring the growth of fungi accounts for the appearance of the latter among the earliest signs of decay of wood."'" The spontaneous decomposition of the vegetable albumen, acting as a ferment, is the primary cause of the decomposition of the wood ; and the presence 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 albu- men 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 other 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. Pay en f). Before a considerable quantity of wood is appro- priated 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 * The growth of mushrooms is found to be remarkably accelerated by watering them with a solution of sulphate of ammonia, t Coui^s de Chimie Organique, 1843. 184 PRESERVATION OF WOOD. 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 process as the preceding from affording anything more than an approximation to the proportion of albumen, a more advantageous me- thod would be to determine the absolute amount of nitrogen in the wood by the simple and easy process devised by MM. Will and Varrentrapp for the ulti- mate analysis of organic bodies. From the propor- tion of nitrogen thus obtained, that of the albumen in the wood may be calculated; but such a calcu- lation is unnecessary, as the relative amount of ni- trogen 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. If the decay of wood is, in the first place, an in- duced effect of the contact of decomposing albumen, a means of preserving the wood is naturally suggested in the removal of the albumen ; or else, in so modify- ing it, by causing it to combine with other sub- stances, that it shall no longer possess the property of decomposing spontaneously. The solubility of albumen in cold and tepid water affords a simple means of withdrawing from the wood this element of decomposition. Unless the wood PRESERVATIVE MATERIALS. 185 is in very thin pieces, however, the removal of the albumen by the process of washing in water is ex- tremely slow. To test the efficacy of merely washing in water, equal weights of washed and unwashed wood, equally dry, were moistened with the same quantity of water, and the amount evaporated was replaced in each quantity equally. In the course of a few weeks the unwashed wood was always found to be covered with a thick mould, while none ap- peared on the washed wood for six months. At the expiration of that period the unwashed wood was found to have sensibly diminished 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 five or six to less than one per cent. But, as the removal of the albumen seems to dimin- ish 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 which is insoluble in water, and not susceptible of spontaneous decompo- sition. 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 vapour, 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 * The use of corrosive sublimate was previously suggested to the Admiralty and Navy Board by Sir H. Davy ; but, this substance being slightly volatile at common temperatures, it was considered that the at- 186 PRESERVATION OF WOOD. drj-rot, under the idea of its acting as a poison to the 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 admitted 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 de- pends on the formation of a compound of lignin, or pure woody fibre, with corrosive sublimate, which re- sists decomposition in circumstances where pure lignin is liable to decay ; but pure lignin possesses no ten- dency to combine with corrosive sublimate. The action of this substance is in reality confined to the albumen, with which it unites to form an insoluble compound not susceptible of spontaneous decomposition, and, therefore, incapable of exciting fermentation. Vege- table and animal matters, the most prone to decom- mosphere surrounding the prepared timbers might become vitiated, and the proposal was not at that time carried into execution. * 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 solution of corrosive sublimate is mixed with a solution of white of egg in water. It is not, as was formerly supposed, a compound of calomel with albumen, nor is it a direct combination of corrosive sublimate with albumen ; but a mixture of two substances, namely, albuminate of mercury, and muriate of albumen. By washing the precipitate with pure water, the muriate of albumen may be separated from the pre- cipitate, and albuminate of mercury remains behind, mixed with a small trace of calomel formed by the reaction of a little phosphorus in the white of egg on the corrosive sublimate. If the solution of corrosive sublimate is mixed in large excess with the white of egg, the muriate of albumen which is formed remains in solution. The albuminate of mercury is quite insoluble in pure water, and so inert that the poisonous eifects of corrosive sublimate may be counter- acted by swallowing the whites of several eggs immediately after the ex- hibition of the poison. It is soluble in water containing chloride of sodium (and therefore in sea-water), chloride of potassium, and muriate of ammonia. PRESERVATIVE MATERIALS. 187 position, are completely deprived of their property of putrefying or fermenting by tlie contact of corrosive sublimate. It is on this account advantageously em- ployed as a means of preserving animal and vegetable specimens. Its expensiveness in this country is a great obstacle to its extensive employment, but few antiseptic applications are more eifectual. In Mr. Kyan's process the wood to be impregnated 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 ex- hausted by a pinup 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, pro- tected and unprotected pieces 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 temperature and accelerate the decomposition. At the expiration of five years the protected wood was found to be unal- tered, while the same kind of wood, unprotected, became considerably affected before the end of the first year. The action of almost all beneficial materials for impregnating wood may be considered of the same nature as that of corrosive sublimate. The most ancient means of preserving wood consists in the application of an external resinous or oleagi- nous covering, by which air and water are effectually 188 . PRESERVATION OF WOOD. excluded. If the wood is dry and in a sound state before the covering is applied, perfect protection might be thus afforded, provided the wood is not exposed to abrasion. It is essential that the wood be made tho- roughly dry previous to the application of a protective varnish, else its decay is hastened by the impediment which the varnish offers to the evaporation of the moisture. The more effectual method of impregnating the wood throughout its mass with a chemical preservative agent was not practised to any great extent until the last century. The principal substances which have been proposed for that purpose are the follow- ing. (See Mr. John Knowles's "Inquiry into the means which have been taken to preserve the British N"avy, particularly from Dry-rot," 1821.) Tar. Sulphate of copper. Sulphate of iron. Sulphate of zinc. Sulphate of lime. Sulphate of magnesia. Sulphate of barytes. Sulphate of soda. Alum. Carbonate of soda. Carbonate of potash. Carbonate of barytes. Sulphuric acid. Acid of tar (pyroligneous acid). Common salt. Vegetable oils. Animal oils. Coal oil (naphtha). Resins. Quick-lime. Glue. Corrosive sublimate. Nitrate of potash. Arsenical pyrites water (contain- taining arsenious acid). Peat-moss (containing tannin). Creosote and eupion. Crude acetate or pyrolignite of iron. Peroxide of tin. Oxide of copper. Nitrate of copper. Acetate of copper. Solution of bitumen in oil of turpentine. Yellow chromate of potash. Refuse lime-water of gas-works. Caoutchouc dissolved in naph- tha. Drying oil. Bees'- wax dissolved in turpen- tine. Chloride of zinc . PRESERVATIYE MATERIALS. 189 Sulphate of copper (blue vitriol), sulphate of iron (green vitriol), and sulphate of zinc have been em- ployed for a considerable time as preservatives against drj-rot. An objection to sulphate of iron, and es- pecially the persulphate, has been suggested by M. Bryant, in its property of being decomposed into the insoluble subsulphate of iron and free sulphuric acid by the woody fibre, which combines with the subsul- phate, while the free sulphuric acid exercises a corrosive action on the timber, and often causes it to become almost pulverulent. These inconveniences may be obviated by first injecting some oily material into the pores of the wood. In the process for preserving animal and vegetable matters from decay, patented by Mr. Margary in 1837, the wood, previously dried, is soaked in a solution of one pound of sulphate of copper in five gallons of water ; and is allowed to remain in the liquid two days for every inch of its thickness. Instead of the above solution, another is sometimes made use of, composed of a pound of acetate of copper dissolved in fourteen quarts of water with two quarts of crude pyroligneous acid. Like chlo- ride of mercury, sulphate of copper acts by forming an insoluble and stable combination with albumen. Contact with alkalies and alkaline earths greatly accelerates the decay of wood, for these substances enable woody fibre and several other organic matters to absorb oxygen, which do not possess the power of themselves. Thus alcohol, which does not, if pure, absorb oxygen from the air at common temperatures, when mixed with potash, absorbs it with avidity, becoming converted into acetic acid, formic acid, and 190 PRESERVATION OF WOOD. other oxidated products. Several vegetable colouring matters, gallic acid, tannin, and other substances, are affected bj alkalies in a similar manner. An experiment on the durability of timber seasoned with lime was made some years ago on a part of the frame-work and some of the timbers of the Amethyst frigate. At the expiration of ten years the prepared timbers were found to be in a worse condition than the unprepared. Alum effectually counteracts the decomposition of the albuminous matter of the wood ; but it cannot be employed as a preservative material, from its decom- position, under the influence of the woody fibre, into the insoluble subsulphate of alumina, which attaches itself to the fibre, and free sulphuric acid, which exerts a corrosive action on the wood. The soluble subsulphate of alumina (basic alum) would be free from this objection to common alum, and, if made without excess of alkali, might probably be found an efficient application. The antiseptic property of common salt is not with- out an application in the preservation of wood. The durability of the beams and other timber-work in salt-mines is attributable to the action of the salt in restraining decomposition. If kept in a tolerably dry atmosphere, wood impregnated with a solution of com- mon salt resists decomposing agents for a considerable time, and it has been observed that ships employed in the salt-trade are more durable than most others built of the same kind of timber. For a first cargo for ships built along the shores of the Baltic the pre- ference is generally given to salt. PRESERYATIVE MATERIALS. 191 But the deliquescent nature of this substance, in the state it is commonly met with, prevents its em- ployment as a preservative for wood intended for gene- ral purposes. For buildings, however, in which the tem- perature is usually high, wood thus prepared would be found durable and economical. Pure salt has very little deliquescent property ; that possessed by the salt met with in commerce is chiefly due to traces of chloride of calcium and chloride of magnesium. The durability of ships employed in the salt-trade has been referred to the thorough desiccation of the timbers by the hygroscopic property of common salt. More than ordinary durability is also ascribed to ships employed in conveying quick-lime ; an effect of lime which is hardly referable to any other mode of action, for the impregnation of the wood with .lime-water would only facilitate its decay. The saturation of wood with vegetable and ani- mal oils, with a view to its preservation, has been practised in America to a considerable extent. This application of oil appears to have been known to the ancients, and was recommended by Dr. Hales in 1756. The imbibition of the oil by the wood is extremely slow, but the protection thus afforded is very consider- able. To facilitate the impregnation, it has been pro- posed first to expel the air and moisture in the wood by the application of heat : and, as a temperature approaching 600° Fahr. may be attained in an oil- bath, the oil has been made the medium of drying and expelling the air as well as of impregnating the timber ; but the wood which had undergone this pro- cess was found to have diminished in tenacity, and its 192 PRESERVATION OF WOOD. fibres were easily separated from each other. (See Knowles's " Inquiry," before referred to.) In 1811 a proposal was made by Mr. Lukin to impregnate wood with the vapour produced from fixed oils, and extensive works were erected for preparing wood for Government purposes by such a process. But most of the timbers submitted to the vapour became cracked, and rendered quite unfit for the con- struction of ships. The building in which the im- pregnation was efiected, the length of which was thirty-two feet, and the breadth twelve feet, at last exploded ; but the trial was quite adequate to prove the insufficiency of the process. From the general nature of the action of arsenious acid on animal and vegetable substances, its efficacy as a preservative material for wood may be assumed. Mundic water containing arsenic, produced by the oxidation, through the air, of arsenical iron pyrites in contact with water, was proposed for this purpose by Mr. Lukin in 1812 ; but the use of this material was abandoned from its injurious effects on the workmen, the death of two persons being produced through some preliminary experiments to determine the value of the process. The durability of wood is greatly increased by being impregnated with tannin, which acts on the albuminous matter in the same manner as corrosive sublimate. The preservation, for several ages, of large branches and trunks of trees imbedded in peat is wholly refer- able to this action of the tannin and analogous sub- stances contained in the peat. With a view of pro- PRESERVATIVE MATERIALS. 193 ducing in fresh oak-wood the same change which it experiences in bogs, it has been proposed to keep the wood surrounded for some time with peat-moss ; but the experiments undertaken to test the efficiency of the process were failures, from the difficulty of carry- ing the impregnation to any extent. The wood which is taken from bogs, however, when exposed to the weather, becomes weak in the fibre, splits, and is soon impaired in quality (Mr. Knowles). The remarkable antiseptic property of creosote has suggested the application of this substance as a preservative for wood. Creosote is an unctuous liquid found among the products of the distillation of wood, and is contained in the tar of some kinds of wood to the amount of one-fifth or one-fourth of the weight of the tar. In an impure state creosote may be obtained by merely subjecting wood- tar to re- distillation and rejecting the first products, but for its preparation in a pure state, a more complicated pro- cess is necessary, an account of which, together with the properties of this singular substance, will be found in the article on the products of the distillation of wood. The efficacy of tar as an external application to wood may be principally referred to the action of the creosote and eupion which it contains on the albuminous matter in the wood, in the same man- ner as corrosive sublimate. With the view of effecting a deeper impregnation, it has been proposed to steep the wood in boiling tar ; but exposure to a boiling liquid for a short time has always the effect of dimin- ishing the tenacity of wood. On comparing the strength of two pieces of timber, one having been 0 194 PRESERVATION OF WOOD, boiled in tar, and the other in its ordinary state, but quite similar in other respects, the strength of the boiled timber was found to be one-seventh less than that of the unboiled. The wood, however, is rendered better capable of resisting decomposition, and suffers an increase in density and hardness. The process is expensive, and too tedious to be generally adopted. A patent has been obtained in this country by M. "F. Moll for a method of impregnating wood with creo- sote by exposing it to the vapour of the oil of wood- tar, which is the product of the distillation of the tar. The first product which passes over when wood-tar is distilled consists for the most part of eupion. When the distillation has been carried so far that the pro- duct has about the same specific gravity as water, the receiver is changed, and some lime, or an alkali, is added to the distilled liquid to neutralize the free acid which it contains. On applying a much stronger heat to the tar, impure creosote distils over. The wood is exposed to the action of the vapours of eupion and creosote in a cast-iron chamber or tank, furnished with some means for applying heat by steam. The wood should be arranged vertically, if convenient ; but if not, it should rest on an iron grating, so that the vapour obtains free access to the surface of the wood. Before the timber is exposed to the tarry vapour, the tank is heated to a tempera- ture about 90° or 100° Fahr. ; and, after sometime, the water expelled from the wood is drawn off, and the vapour of eupion admitted by a pipe from a contigu- ous boiler. The timber is exposed, in the next place, to the vapour of creosote ; and is, lastly, soaked for some time in hot liquid creosote. PRESERVATIVE MATERIALS. 195 The length of time during which the wood should be submitted to these successive operations depends entirely on its hardness and density. As a means of estimating the progress of the different processes, it is recommended to attach to the tank a small test- chamber containing a small piece of the same kind of wood as that in the tank. By observing "the pro- gress of the test, that of the large piece may be easily judged by an experienced workman. This process may be made, without doubt, an effec- tual means of preserving the wood from decay, but it would seem to be much too complicated and expensive for general adoption on the large scale. The use of the aqueous solution of creosote for pre- serving wood has been patented by Mr. Samuel Hall. One hundred parts of water at common temperature dissolve only about 1-25 parts of creosote. Peroxide and perchloride of tin, and oxide, chloride, and nitrate of copper, are preserving materials, for the use of which a patent was obtained by Mr. Richard Treffry in 1836. To impregnate wood (or any other vegetable material) with oxide of tin or oxide of cop- per, it is first soaked in a mixture of a pound of quick-lime with about four gallons of water, or else in a solution of a pound of soda-ash (containing about 45 per cent, of alkali) in four gallons of water. When taken out of the alkaline solution, the wood is well washed, and, if convenient, dried. It is next dipped into another tank, containing a solution of either per- chloride of tin, chloride of copper, or nitrate of cop- per. It is immaterial whether the wood is first im- pregnated with the alkali or the metallic solution, if 0 2 196 PRESERVATION OF AYOOD. the superfluous liquid remaining on the surface after the first immersion is carefully removed. The me- tallic salt preferred by the patentee for wood is chloride of copper, a pound of which may be dis- solved in six pounds of water, and a sufficient quan- tity of the solution used to cover the timber com- pletely. ■ When dry, the timber is ready for use. It is stated that the chloride, nitrate, and acetate of copper may also be applied to wood with advantage by themselves. The use of a solution of bitumen in oil of turpen- tine, applied externally as a paint, has been patented by Mr. R. Newton. According to the specification of the patent, the method preferred for making the so- lution of bitumen is the following : — The bitumen is melted in an iron boiler heated by means of steam, and ten per cent, of common turpentine is added during the melting. When fluid, seventy-five per cent, of oil of schistus, or other mineral oil, is added, the mixture stirred, again heated, and afterwards poured out into an iron vessel to cool. When cold, there are added, first, twenty-five per cent, of com- mon turpentine, and afterwards ten per cent, of hy- drate of lime previously sifted and mixed with a small quantity of the liquid. This mixture is said to remain in a permanently liquid state at common temperatures. The use of a solution of yellow chromate of potash as a preservative agent has been patented by Mr. John Bethell (July, 1838). The bichromate of potash would probably be found a more efficient preservative material than the yellow chromate. Mr. Bethell's PRESERVATIVE MATERIALS. 197 patent also includes the application of the refuse lime- water of gas-works ; of a solution of caoutchouc in naphtha or turpentine, alone, or mixed with rape- oil, coal-tar, or wood-tar ; of a solution of bees'-wax in turpentine, and of drying oil and turpentine. These mixtures are said to impart to the wood both durability and impermeability to water. The process patented by Sir William Burnett in 1838, for preserving wood and other vegetable mat- ters from decay, consists in impregnating them, in the ordinary manner, with a solution of chloride of zinc, containing one pound of the chloride to five gallons of water. The time required for the digestion of the wood in the solution at common atmospheric pressure varies from ten to twenty-one days, accord- ing to the thickness of the wood. Pieces of four inches in thickness, or less, require ten days ; pieces of from four to eight inches require fourteen days ; and pieces above eight inches require twenty-one days. The timber should be dried in a sheltered situation. It is recommended as an additional pre- caution that a paint composed of oxide of zinc and drying oil be applied to the wood externally. The protection from decay afforded to wood by chloride of zinc is said to equal that afforded by corrosive sublimate. Chloride of zinc is better adapted to the preservation of shipping than corrosive - sub- limate, as the compound which oxide of zinc pro- duces with vegetable albumen is insoluble in sea- water, unlike the compound of oxide of mercury and vegetable albumen. Specimens of English oak, English elm, and Dantzic fir remained perfectly sound for five 198 PRESERVATION OF WOOD. years in the fungus test-pit at Woolwich (see page 187); but similar unprepared pieces introduced at the same time soon became affected with decay and fungus. The protection afforded to canvass and cordage by chloride of zinc appears to be greater than that by chloride of mercury. The impure mixture of acetate of peroxide and acetate of protoxide of iron (pyrolignite of iron or dyers' iron liquor), obtained by digesting rusty iron nails, &c. in the crude acetic acid afforded by the distillation of wood, is one of the most economical and efficient of preservative agents. It forms a stable compound with albumen ] its acid, when free, exerts no corrosive action on the wood, and being volatile, may be easily expelled from the wood, if necessary, by the application of heat ; and lastly, the crude acetate contains a considerable quantity of creosote (page 193). Vegetable matters which easily enter into a state of putrescence, as paste and pulps of carrot and beet- root, are rendered almost inalterable in the air by being soaked in a solution of the crude acetate. The iron liquor generally employed for preserving wood has the specific gravity 1'056. To determine the relative amount of protection from decay afforded by the most important of the preceding preservative agents to vegetable matters placed in the same conditions as to moisture and tem- perature, Dr. Boucherie instituted a set of experiments on wheat flour and pulp of beet-root, of which the following are the results. The experiments, which were all performed at the same time, consisted in PRESERVATIVE MATERIALS. 199 mixing equal weights of the vegetable matter, equally- moist, with different quantities of the bodies the protective power of which was to be determined. In all the experiments with wheat flour, 62 grammes were mixed with 30 grammes of water containing the preservative material in solution. A mixture of flour and water only, made for comparison, became completely covered with mould, and evolved a consi- derable quantity of putrid gas, on the eighth day after, being made. Chloride of mercury. — Three experiments were per- formed with this substance, in which 2, 4, and 6 decigrammes were dissolved in the 30 grammes of water for mixing with the flour. No alteration had taken place in either of the mixtures at the expiration of two months. Sulphate of iron. — In five experiments with sul- phate of iron, in which from 2 decigrammes to 2 grammes were dissolved in the 30 grammes of water, the appearance of the mould was retarded only a few days. In each mixture it was complete on the twelfth day. Pyrolignite of iron. — In an experiment in which 1 decigramme of dyers' iron liquor of specific gravity r055 (ir Twaddell) was mixed with the usual quan- tity of flour and water, a slight mould appeared on the tenth day ; with 2 decigrammes, on the twelfth day ; with 3 decigrammes, on the fifteenth day ; with 4 decigrammes, on the twentieth day ; with 5 deci- grammes and upwards no mould was perceptible up to the sixtieth day. Arsenious acid. — With 2 decigrammes of arsenious 200 PRESERVATION OF WOOD. acid some mould appeared on the thirteenth day ; with 4 decigrammes, on the fifteenth day ; and with 1 gramme, on the eighteenth day. With 2 grammes no decomposition was perceptible up to the sixtieth day. Similar results were obtained in experiments with the pulp of beet-root. The decomposition of the pulp was completely prevented by a decigramme of cor- rosive sublimate ; but a gramme and a half of either sulphate of iron, sulphate of copper, or sulphate of zinc only retarded the decomposition of the same quantity of pulp for a few days. A gramme of iron liquor and 6 decigrammes of crude pyroligneous acid were found to be requisite for complete preservation. § IV. MODES OF APPLYING PRESERVATIVE AGENTS. Until lately, the only method commonly prac- tised of conveying a preservative material to the interior of a piece of wood consisted in steeping the wood in a solution of the substance, or else in expos- ing the wood to the vapour of the preserving body. A billet of wood placed on its end and covered with an aqueous solution gradually absorbs a considerable quantity of the liquid merely by the force of capillary attraction, aided by the pressure of the liquid column. But the impregnation is effected very unequally in this manner, certain parts of the wood presenting far greater facilities for the transmission of the liquid than others. Those parts near the axis, where the tissue is denser than towards the surface, are scarcely at all penetrated by the solution. MODES OF APPLYING PRESERVATIVE AGENTS. 201 The impregnation also takes place with extreme slowness ; a piece of wood of about three feet three inches in length, and nine inches in diameter, con- tinued to absorb water and increase in weight after having been submerged in water for ten months. To obtain a more perfect and rapid impregnation of the wood. Dr. Boucherie* suggested the applica- tion of the aspirative force of the tree, the liquid being applied either to the base of the trunk or larger branches, or to the roots. It is indifferent whether the tree is still standing or recently felled. By this force, the liquid is absorbed, in the course of a few days, to a height of eighty or a hundred feet, and even penetrates to the leaves. f To impregnate a tree recently felled, the base of its trunk may be placed in a vat containing the solution of the preserving material, or else a bag of leather or sheet caoutchouc may be fastened water- tight around the base and put in communication by means of a pipe with a tank or cistern containing * Annales de Chimie et cle Physique, t. Ixxiv., 113. t A patent was obtained by Mr. John Bethell for a process for im- pregnating wood identical in most respects with that of Dr. Boucherie, the butt-end of the recently felled tree being placed in a tank contain- ing the solution, or else the solution is contained in a bag of water- proof cloth afSxed to the end of the tree. The process was patented in July, 1838, which was previous to the publication of Dr. Boucherie's paper. This method of impregnating wood has been favourably reported on by a commission of the French Academy, consisting of MM. Dumas, Boussingault, De Mirbel, Arago, Poncelet, Audouin, and Gambey ; and extensive arrangements have been undertaken in France, by the Minis- ter of Marine, for the application of the process to the preservation of wood for the French navy. 202 PRESERVATION OF WOOD. the solution. A poplar of about ninety feet in height, the base of which was placed in the month of Sep- tember in a vat containing a solution of pyrolignite of iron of specific gravity 1'056, absorbed 3 hecto- litres (very nearly 10*6 cubic feet) of the solution in the course of six days. The time which may be allowed to elapse between the felling of the tree and the impregnation varies according to the nature of the tree and the season of the year. At the end of September, a pine, the trunk of which was fifteen inches and a half in diame- ter, became perfectly impregnated, when put in con- tact with the solution, forty-eight hours after being felled. In the month of June a plantain was also well penetrated after having been cut down for thirty- six hours. But the sooner the tree is put in contact with the liquid after being cut, the more energetic is the absorption. At the tenth day the aspirative force is hardly sensible. As the tree should be maintained in a vertical position, its great weight may often become inconve- nient to sustain ; it is hence sometimes found more ad- vantageous to operate on the tree before it is wholly detached from its roots. To impregnate a standing tree, two deep notches may be made with a saw on each side of the trunk, into which two narrow wedges are to be inserted to support the tree; or an auger-hole of two or three inches in diameter may be bored through the centre of the tree, and a horizontal cut made by a saw, right and left of the hole, enough of the outside being left to susta-in the tree. A bag of tarred leather or sheet MODES OF APPLYING PRESERVATIVE AGENTS. 203 caoutchouc is then fastened around the trunk above and below the notches, and placed in communication, by a pipe, with a cistern containing the preserving solution ; or else the solution may be contained in a basin of well-tempered clay, large enough to hold two or three gallons of liquid, made around the base of the trunk. To avoid waste of the liquid, the tree may be stripped of its superfluous branches before being submitted to the process. A terminal tuft, however, should always be allowed to remain. The best season of the year for impregnating the tree, according to the experience of Dr. Boucherie, is the autumn. The impregnation is more difficult to effect in deciduous trees in spring than in winter or summer, but evergreens may be impregnated advantageously in winter. Different kinds of liquids are not absorbed with equal facility; neutral solutions, for example, are absorbed more readily than either acid or alkaline. A plantain, the trunk of which was about twelve inches in diameter, absorbed in seven days two and a half hectolitres (very nearly 8*8 cubic feet) of a solution 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, 204 PRESERVATION OF WOOD. has since been discovered by Dr. Bouclierie, and also, independently, by Mr. W. H. Hyett, of Stroud, Glou- cestershire, whose Prize Essay on the best solutions for impregnating trees to impart durability, incom- bustibility, &c., in the Transactions of the Highland Society,* contains a great deal of highly valuable information. The process consists simply in invert- ing 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 extremity, or in a cup hollowed out of the end of the tree. In most cases, the liquid quickly penetrates by the supe- rior 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 in 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' * Vol. viii. New Scries, 1843, p. 535. MODES OF APPLYING PRESERVATIVE AGENTS. 205 growth immediately around the pith, admitted the sohition 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 intro- ducing the liquid under a considerable pressure. This method was patented by Mr. John Bethell in 1838. The vessel in which the impregnation is effected is an air-tight iron tank of sufiicient strength to withstand an internal pressure of two hundred pounds to the square inch. The circular wrought-iron boilers for high-pressure steam-engines are well adapted for the purpose. The tank is fitted with an air-tight lid or door, and with a conunon steam-boiler safety- valve, and is connected by one pipe with an exhaust- ing 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 readmitted, and the liquid forced into the ex- hausted 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 out- side of the tank ; in others, the liquid enters readily after the exhaustion, without the assistance of pres- sure. The escape of air from the pores of the wood is expedited by placing the logs of wood in a per- 206 PRESERVATION OF WOOD. pendicular 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 containing about nineteen or twenty loads of timber. It is fitted out with a set of exhausting pumps, and a set of pressure-pumps, and has been proved up to 200 pounds to the square inch. When the cylinder is loaded, the air is exhausted to 27*5 inches of mercury, and the liquid is introduced by a pipe in connection 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 re- newed, whereby the fluid is driven into every pore of the wood.* § V. OTHER EFFECTS OF THE IMPREGNATION OF WOOD WITH FOREIGN SUBSTANCES. Besides protection from decay, whether the wood be kept in a dry or humid state, the following effects may be produced by impregnation with certain 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 contrac- tion of the wood, and the disjunctions which conse- * United Service Journal, April, 1843. IMPREGNATION WITH FOREIGN SUBSTANCES. 207 quently occur in buildings through variations in the hygrometric condition of the atmosphere ; 5. The application of various persistent colours and odours ; and 6. The increase of the density of the wood. 1. From the effects of wood prepared with pyro- lignite of iron (page 198) on cutting tools, its hard- ness has been estimated by workmen at double that of the unprepared wood. Of some specimens of beech impregnated by Mr. Hyett, a carpenter considered 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 sulphate 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. Bou- cherie, 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 preserved 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 208 PRESERVATION OF WOOD. proportion to the quantity of saline matter intro- duced. A plate of pine-wood charged with the mother-liquor, of three millimetres ("llS inch) in thickness and sixty centimetres (23*6 inches) in length, was capable of being bent into three con- centric circles without being broken, and when al- lowed, 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 be- come dry by exposure to the sun in the middle of summer, and the little moisture lost by the wood during the day is again absorbed at night. The adherence of paints and resinous varnishes does not seem to be affected by the application of these de- liquescent 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 pyrolignite. 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. Pieces of larch impregnated with acetate of copper and sulphate of copper were found to be far 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 horizontally in a frame IMPREGNATION WITH FOREIGN SUBSTANCES. 209 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 shew the mean of the three observations for each piece. I. DEFLECTION OF LARCH, IN INCHES. Weight applied in pounds. Chloride of calcium. No. 13.* Sulphate of iron. No. 19.* Sulphate of copper. No. 20.* Corrosive sub- limate. No. 21.* Acetate of copper. No. 22.* Pyrolignite of iron. No. 23.* Natural state. No. 24.* Prussiate of potash. 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 1^11 33 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 218, 219. P 210 PRESERVATION OF WOOD. II. DEFLECTION OF BEECH, IN INCHES. 56 112 140 154 161 168 174 180 184 188 192 196 200 204 208 212 216 220 224 229 233 238 243 247 252 257 261 266 270 274 279 283 288 1 26 2-41 •51 •06 •33 •5 •6 •65 •71 •76 •81 •83 •88 •91 •96 1^00 1^05 1^08 rii 1^15 1^2 1-26 1^31 1-4 1^5 1.6 1^68 1- 8 1^96 2^05 2- 21 2-4 2^58 2-83 3^16 3^48 •26 •63 •85 1^0 1^1 1^18 1^26 1-36 1^45 1-51 1^6 1^66 r76 1-85 1- 95 206 2- 16 2^3 2-41 2-6 2- 78 3- 01 •4 M6 •26 •83 1^2 1-41 1-55 1^73 1^88 2^06 •36 M 1- 8 2- 9 •33 •86 1-26 1-55 1- 76 2^0 2^21 2- 48 2^76 31 3- 6 3^98 •38 •84 1-16 1-37 1-49 1-66 1-79 1- 95 21 2- 27 2-48 2-69 * The numbers refer to the table, pages 218, 219. IMPREGNATION WITH FOREIGN SUBSTANCES. 211 From the results of Mr. Hyett's experiments, con- tained in the preceding tables, it appears that the strength of the wood may be greatly increased or diminished by impregnation with foreign substances, and that it is most diminished by those substances which tend most to preserve or increase the Hexibility 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 fi;\- t i:o 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, liie piece of beech which shewed 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 affected in a similar man- ner 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 in- creasing the weight, and the reverse. The preceding tables also lead to the important conclusion that the two different classes of trees, resinous and non-resinous, require very different treatment. In the beech, and probably all other non-resinous trees, prussiate of potash and pyrolig- nite 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 cop- r 2 212 PRESERVATION OF WOOD. per 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 influence. 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 applied 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 combus- tibility 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 in- flammability of the wood diminished, but its com- bustion, when fairly commenced, is rendered difiicult by the access of air to the carbonized wood being impeded by the thin film of fused alkaline or earthy salt. Two huts, one built of prepared wood, and the other of unprepared, were set on fire at the same IMPREGNATION WITH FOREIGN SUBSTANCES. 213 time by applying equal weights of the same lighted combustible matter. When the hut built of ordinary wood had become reduced 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 inflamma- bility of prepared and unprepared wood. 4. The expansions and contractions which wood often experiences through changes in the hygrometric state of the atmosphere, and the consequent loosen- ing of joints which thereby occurs, may also be pre- vented or diminished by impregnation with some deli- quescent substance. According to Dr. Boucherie, wood containing a small amount of moisture is not subject to these changes in volume, and they may be entirely prevented by a little chloride of calcium or chloride of magnesium. A few large thin tables made of wood thus prepared underwent no change in form or size during a twelvemonth, while similar tables in the same situation, made of unprepared wood, became exceedingly warped. The addition of a little pyrolignite of iron to the deliquescent sub- stance is also recommended, to ensure durability. 5. The colours which are most easily applied to wood by the aspirative process 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 tint, the wood may be first impreg- nated with a solution of yellow prussiate of potash, and afterwards with a solution of persulphate of iron ; 214 PRESERVATION OF WOOD. or the same solutions may be applied in the reverse order. The tint in this case is derived from Prussian blue. A black tint may be imparted by introducing successively a solution of sulphuret of sodium and a solution of acetate of lead, whereby sulphuret of lead is produced. 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 of acetate of copper and arsenious acid ; a reddish brown (prussiate of copper), by sulphate of copper and yellow prussiate of potash ; and a delicate yellow (chrome yellow), by acetate of lead and bi- chromate of potash. A solution of sulphate of cop- per, to which a slight excess of ammonia has been added, penetrates the wood with facility, and pro- duces an agreeable blueish tint. As the impregnation is not effected equally through the whole substance of the wood, the tinting is not uniform, but in veins and waves, which present an agreeable appearance when the wood is worked up and polished. According to Mr. Hyett, different 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 coloured most, and the heart-wood least, when the acetate was introduced first. But when the prus- siate was first applied, the heart-wood became most deeply coloured. With sulphate or acetate of cop- per first, and prussiate of potash next, beech may be made to appear very much like mahogany. Iodide IMPREGNATION WITH FOREIGN SUBSTANCES. 215 of lead and iodide of mercury cannot be applied to wood with advantage as colouring materials. Pyrolignite of iron alone produces in beech a dark grey colour, from the action of the tannin contained in the wood on the oxide of iron ; but in larch and Scotch fir it merely darkens the natural colour of the wood. Prussiate of potash alone produces a dingy green colour. The tints of most of these colouring materials, especially of the prussiates of iron and copper, are improved by exposure to light; and the richest colours are obtained when the process is ra- pidly executed. (Mr. Hyett.) Vegetable colouring matters do not easily penetrate the wood by the aspirative process, probably on ac- count of the affinity of the woody fibre for the colour- ing principle, whereby the whole of the latter is abstracted from the solution 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 the wood in a state of solu- tion in weak alcohol ; and the odours thus imparted are considered to be as durable as those supplied by nature. Wood may also be impregnated with resin- ous substances in alcoholic solution, by which it may be rendered impervious to water, and far more in- flammable. 6. The increase which wood experiences in density by being impregnated with foreign substances is shewn in the following tables drawn up from the experiments of Mr. Hyett. 216 PRESERVATION OF WOOD. SPECIFIC GRAVITY OF PREPARED BEECH. No. in Table, Preparation. Specific gravity, pages 218 and 219. No. 28. Dried 2 years over stove 681 26. Soaked in water 2 years and dried in air 3 years 763 2. Nitrate of soda 809 7. Sulphate of iron 832 17. Natural state (green) 340 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 gravity, pages and 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 iron 608 IMPREGNATION WITH FOREIGN SUBSTANCES. 217 The most important results of Mr. Hyett's expe- riments on the best materials for impregnating wood are embodied in the following table. 218 PRESERVATION OF WOOD. RESULTS OF EXPERIMENTS ON By Mr. W. H. Hyett. Experiment. May 3 May 5 May 6 July 13 May 13 May 15 May 14 June 2 July 13 July 30 July 13 24 22 23 30 19 21 19 17 17 20 20^ 12 17 15 14 14^ 17 17 17 17 17 17 Tree. Beech Larch Scotch fir Larch Lime Elm White poplar Beech Larch Beech Pear Beech 56 56 50 i 56 56 56 56 56 12 12 12 12 12 56 56 12 12 12 12 55 45-5 A Cl imperfect 12 12 12 34 42 54^ 28^ 34i 32 29 22 34 21 18 241 37 34 351 291 36 33 6* 6§ 7 Material applied. Corros. sub. Nitr. soda Pruss. pot. Imp. gas-tar Pyrolig. iron Com. salt Sulph. iron Sulph. cop. Acetate cop, & vinegar Gas-tar Do. Corros, sub Chlor.of cal, Corros. sub. Do. Do. Nat. state Sulph. iron Do. SiJph. cop Corros. sub Acetate cop & vinegar Pyrolig. iron Nat. state Pruss. pot. 2 13f large old timber, cut 5 years, soaked in water con taining much carbonate of lime for 2 years, and afterwards dried in an open shed, cut 5 years and perfectly dried over a stove, cut 2 years and perfectly dried over a stove 1 i ^ pmt S Saturated solution 1 18 1 pint J s. d. 4 12 3 3 8 9 0 "h 6 3 14 0 4 17 2 10 17* 8 7i 174 14 2 1 0 3^ 1 0 3^ 94 2 4^ 9 3 0 9i 2 4i 7i 1 10^ 10 2 6 12^ 2 1 15 7 6 lOf 2 8 13i 11 0 1 0 10 IMPREGNATION WITH FOREIGN SUBSTANCES. 219 MATERIALS FOR PRESERVING WOOD. ( Trans, of the Highland Society.) Timber, its weight and strength. tlfi weight in pounds ired to brealc. rage deflection be liting, in inches. Observations on the state of preservation of the prepared woods after having remained for nine months in a damp cellar surrounded with decaying saw-dust full of fungi. < « 0) 844 809 876 858 859 Q.Q.Q OOO 832 866 240 162 302 247 261 176 1 no 2 158| 3-63 3- 76 4- 3 2- 9 3- 81 2- 9 2*71 3- 33 ^ Very clean and dry, except where the sokition had ( not touched, where there are fungi. Covered with fungi, not very damp. Tendency to fungi and decay. r iTno"! "nfiTtiPnljirlv nn TinTtc: wliAri^ flip tor o'Kfinn/lc" Clean and dry. Very wet, hlack, 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 1 OI Tendency to fungi and decay. 600 140 3-6 Dry and clean, with little or no fungi. 474 560 474 DdU 102 1411 108i 152 2- 6-33 3-25 6- Light, dry, and clean. Tendency to decay. A little fungi. Much fungi. 434 126| 4-33 Dry and clean. 840 2461 5-35 828 259| 5-5 Fungi and mouldiness. 595 533 541 140 9] 116 5-66 3-46 3-5 Clean where solution had touched, but not elsewhere. Clean, but a little fungi. Dry and clean. 552 1001 6-5 Dry, with a little fungi. 608 488 551 1371 88| 88| 5- 23 6- 83 2-23 1 Clean and dry, except on the parts untouched by the ( solution. Clean and dry. Light and diy, but a little fungi. 763 732 681 282 229 257 2-66 2- 5 3- 3 Wet, tendency to decay and fungi. Dry and clean. 221 DYEING AND CALICO-PEINTING * § I. History of Dyeing and Calico-printing. — II. General Properties of Vegetable Colouring Matters. — III. General Nature of Dyeing Pro- cesses. — 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 che- mical nature of tinctorial substances, yet dyeing is strictly a chemical art, , and it cannot be properly understood without some acquaintance with the che- mical properties of the acting bodies. The great object of all dyeing operations is the impregnation of a textile fabric with coloured sub- stances derived from animals, vegetables, and mi- nerals, in such a manner as to render them incapa- ble of being removed by washing with water. The modes of efiecting this object vary as greatly as the colouring matters diflfer from each other in their chemical habitudes. Though the chemical re-actions which are exhibited in the various dyeing and print- * For a considerable portion of the materials from which the present article is compiled, I am indebted to Mr. Mercer, of the Oakenshaw print-works, near Blackburn, and to Mr. John Graham, of the Mayfield print-works, Manchester. 222 DYEING AND CALICO-PRINTING. ing processes are, for the most part, sufficiently in- telligible, yet tliey are sometimes of a highly com- plex character; and the theoretical principles of a few valuable processes, discovered accidentally, are even yet but imperfectly understood. § I. HISTORY OF DYEING AND CALICO-PRINTING. In the East Indies, in Persia, in Egypt, and in Syria, the art of dyeing has been successfully prac- tised from time immemorial. In the books of the Pentateuch frequent mention is made of linen cloths dyed blue, purple, and scarlet, 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 colour was prized so highly, that in the time of Augustus a pound of wool dyed with that ma- terial cost, at Rome, a sum nearly equal to thirty pounds of our money. The Tyrian purple is now generally believed to have been derived from two different kinds of shell-fish, described by Pliny under the names purpura and buccinum^ and was ex- tracted from a particular organ in their throats to the amount of one drop from each fish. It is at first a colourless liquid, but by exposure to air and light becomes successively citron-yellow, green, azure, HISTORY OF DYEING AND CALICO-PRINTING. 223 red, and, in the course of forty-eight hours, a bril- liant purple. If the liquid is evaporated to dryness soon after being collected, the residue does not be- come coloured in this manner. The purple is re- markable for its durability ; it resists the action even of caustic alkalies and most acids. Plutarch ob- serves in his Life of Alexander, that, at the taking of Susa, the Greeks found in the royal treasury of Darius a quantity 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 colouring juices of shell- fish have been investigated by Cole, Gage, Plumier, Duhamel, and Reaumur, who have succeeded in pro- curing a purple dye, though inferior to what may be obtained by other dye-stuffs. It does not appear that the art of dyeing was much cultivated in ancient 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 with copperas. The progress of dyeing, as of all other arts, was completely arrested in Europe, for a considerable time, by the invasion of the northern barbarians in the fifth century. In the East the art still con- tinued to flourish, but it did not revive in Europe 224 DYEING AND CALICO-PRINTING. until towards the end of the twelfth, or the begin- ning of the thirteenth century. One of the prin- cipal places where dyeing was then practised was Florence, where it is said there were no less than two hundred dyeing establishments at work in the early part of the fourteenth century. One of the Florentine dyers having ascertained, in the Levant, a method of extracting a colouring matter from the lichens which furnish archil, introduced this ma- terial into Florence on his return; by its sale he acquired an immense fortune, and became one of the principal men of the city. I The discovery of America tended greatly to the } advancement of the art, as the dyers became supplied ) from thence with several valuable colouring materials / previotisly unknown in the old world ; amongst which I are logwood, quercitron. Brazil-wood, cochineal, and ( annatto. A great improvement in dyeing also took J place about the year 1560, which consisted in the S introduction of a salt of tin as an occasional sub- \ stitute for alum. With cochineal, the salt of tin was found to afford a colour far surpassing in bril- V liancy any of the ancient dyes. The merit of this / application is attributed to Cornelius Drebbel, a ) Dutch chemist, whose son-in-law established an ex- / tensive dye-house at Bow, near London, about the I year 1563. About the middle of the sixteenth century, log- wood 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 log- wood was prohibited, in England, by Queen Eliza- beth, by a very heavy penalty, and all found in the HISTORY OF DYEING AND CALICO-PRINTING. 225 country was ordered to be destroyed. Its use was not permitted in England till the reign of Charles the Second. Indigo, one of the most valuable and important of dye-stuffs, was also forbidden to be used in England and on the continent, and de- nounced as " food for the devil." These, and similar prejudices, were gradually sur- mounted, and in the eighteenth century the art of dye- ing made very considerable progress. Madder, from which the colour known as Turkey or Adrianople red is produced, then began to be properly appre- ciated ; and quercitron, a fine yellow dye, was brought extensively into notice by Dr. Bancroft. But the chief improvements of the moderns in this art con- sist in the employment of pure mordants, and in the application of colours derived from mineral com- pounds, as peroxide of iron, Prussian -blue, chrome- yellow, chrome-orange, manganese-brown^ &c. Each of these colouring matters may be obtained as an in- soluble 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 impregnating it first with one solution, and af- terwards with the other. As the precipitate thus produced is imprisoned within the fibre, it is not removable by mere washing with water. The mode of dyeing Turkey red, which is the most durable vegetable colour known, was discovered in India. It was afterwards practised in other parts of Asia and in Greece ; and, about the middle of last century, dye-works for this colour were established near Eouen and in Languedoc by some Greek dyers. In 1765, the French government, convinced of theim- Q 226 DYEING AND CALICO-PRINTING. portance of the process, caused an account of it to be published ; but it was not introduced into this country until the end of last century, when a Turkey-red dye-house was established in Manchester by M. Bo- relle, a Frenchman. M. Borelle obtained a grant from Government for the disclosure of his process, but the method which was published does not seem to have been very successful. A better process was introduced into Glasgow about the same time by another Frenchman, named Papillon. Previous to this, however, Mr. Wilson of Ainsworth, near Man- chester, 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 this country is still carried on in the Glasgow district. The ancients seem to have attained considerable proficiency in the art of topical dyeing, or of pro- ducing coloured patterns on cloths. The variegated linen cloths of Sidon are noticed by Homer, who lived nine hundred years before Christ, as very magnificent productions. In India the art of im- parting a coloured pattern to a cotton fabric has been practised with great success from time imme- morial, and it derives its English name of calico- printing from Calicut, 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, HISTORY OF DYEING AND CALICO-PRINTING. 227 the inhabitants of Caucasus adorned their garments with representations of various animals by means of an aqueous infusion of the leaves of a tree; and the colours 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 they 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 acquired by extensive prac- tice and close observation. " An extraordinary method of staining cloths is practised in Egypt. They there take white cloths and apply to them, not colours, but certain drugs which have the power of absorbing or drinking in colour ; and in the cloths so operated on there is not the smallest appearance of any dye or tincture. These cloths are then put in a cauldron of some colouring matter, scalding hot, and after having re- mained a time are withdrawn, all stained and painted in various colours. This is indeed a wonderful process, seeing that there is, in the said cauldron, only one kind of colouring material ; yet from it the cloth acquires this and that colour, and the boiling liquor itself also changes, according to the quality and nature of the dye-absorbing drugs which were at first laid on the white cloth. And these stains or colours, moreover, are so firmly fixed as to be q2 228 DYEING AND CALICO-PRINTING. incapable of being removed by washing. If tiie scalding liquor were composed of various tinctures and colours, it would doubtless have confounded them all in one on the cloth; but here one liquor gives a variety of colours, according to the drugs previ- ously applied. The colours of the cloths thus pre- pared are always more firm and durable than if the cloths were not dipped into the boiling cauldron." (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 de- scribed. The pallampoors^ or large cotton chintz counter- panes made in the East Indies 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 colour when immersed into the vessel containing the dye. The topical dyeing of cotton goods seems to have been practised for a considerable time in Mexico. When Cortez conquered ^jthat^country , he sent to Charles V. cotton garments with black, red, yellow, green, and blue figures. The North American In- dians have also been for a long time in possession of a mode of applying patterns in different colours to cloth. The art of calico-printing does not appear to have been much practised in Europe until the close of the seventeenth or the beginning of the eighteenth cen- tury, when Augsburg became famous for its printed cottons and linens. From that city the manufac- HISTORY OF DYEING AND CALICO-PRINTING. 229 turers of Alsace and Switzerland were long supplied with colour-mixers, dyers, &c. The first print- ground in England was founded by a Frenchman on the banks of the Thames near Richmond, and soon afterwards a more considerable one was established at Bromley Hall in Essex. Several others were some time afterwards founded in Surrey, in order to supply the London shops with chintzes, the impor- tation of which from India had been prohibited by an act of parliament passed in 1700, on account of the excessive clamours of the silk and woollen weavers. Though merely intended as a protection to the Eng- lish silk and woollen manufacturers, this act had the effect of greatly stimulating and increasing the infant art of calico-printing; for the demand for printed calicos ^nd chintzes could then be gratified only by printing, in this country, white Indian calicos, the importation of which was still allowed under a duty. An excise duty of threepence per square yard was imposed on the printed calicos in 1712, which was increased to sixpence in 1714 ; but the importation of calico being still considerable, a new alarm was raised, and_ajaw3actedin^ the wearing of all printed calicos 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 re- pealed in 1730; but the calicos then permitted to be printed were to have the warp of linen and merely the heft of cotton, and were subject to a duty of sixpence per square yard. With such discourage- ments, the progress made in calico-printing was ex- 230 DYEING AND CALICO-PRINTING. tremely slow : so lately as the middle of last century it was computed that only fifty thousand pieces of the mixed cloth were printed annually in the whole of Great Britain ; whereas, at the present time, se- veral 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 re- quired to be made of linen yarn was repealed in 1774; but the printed calicos 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 con- sumer. The wonderful developement which calico-printing has received within the last half-century is to be attributed, in a great measure, to the adaptation of numerous ingenious mechanical inventions. The im- provement in patterns, and the reduction in the price of cotton prints during this period, are striking illus- trations of the advancement which has been made in machinery. The first improvement on the or i- ginal wooden hand-printinp^ ^Igg^ * 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 em- ployed for printing engravings on paper), on which a much more delicate pattern could be engraved than on wood. The colour being laid on the cop- per plate and the superfluous colour removed by a thin steel scraper, the plate was passed with the * A description of the various modes of printing cloths now practised •will be found in another part of the present article. HISTORY OF DYEING AND CALICO-PRINTING. 231 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 improvement 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 independ- ently by a Scotchman of the name of Bell, and was first successfully applied in the large way about the year 1785, at Mousey near Preston. Cylinder print- ing has received its greatest developement in Lan- cashire; and the perfection to which the process has been there brought is the chief cause of the admitted superiority of our calico-printing establish- ments 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 labour 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 by the ordinary method of block-printing in six hours. A length of calico equal to one mile has been printed off with four different colours in a single hour. The successful application of an engraved copper cylinder was followed by that of a wooden roller 232 DYEING AND CALICO-PRINTING. having the pattern in relief, the mode of printing by which is known as " surface printing. " The "union" or "mule machine," which is a combina- tion in one machine of the engraved copper cylinder with the wooden roller in relief, was invented about 1805 by Mr. James Burton of Church, near Blackburn. One of the most important of recent improvements in the mechanical department of calico-printing is a very ingenious method of executing block-printing with several colours by press-work in an arrange- ment similar to one of the modern type-printing machines. (An account of this mode of printing is contained in another section of the present paper.) Another important modern improvement, more par- ticularly 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 Berthollet, and numerous and valuable improvements were sug- gested by some of their researches. The application of chlorine, by Berthollet, to the bleaching of tis- sues, especially cotton and flax, contributed in no small degree to the advancement 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 che- mistry. The chief improvements introduced by the moderns consist, as already observed, in the ap- plication of colours derived from mineral substances. PROPERTIES OF VEGETABLE COLOURING MATTERS. 233 Among the earliest introduced of this class of bodies, were iron buff and Scheele's green, which were fol- lowed 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 afterwards Mr. Mercer first applied, on the large scale, the peroxide of manganese, known ' as manganese bronzQ. § 11. GENERAL PROPERTIES OF VEGETABLE COLOURING MATTERS. By far the greater number of the colouring mat- ters employed in the art of dyeing are derived from vegetables, but the animal and mineral kingdoms also contribute a small number. Colouring principles are abundantly distributed over all the organs of vegetables, but never in a state of purity; they are always mixed, more or less, with other sub- stances, and their isolation in a pure state often re- quires very complicated processes. Only a small number, comparatively, of these substances have as yet been obtained sufficiently pure to have their chemical composition determined. Like almost all other vegetable principles, they are composed either of carbon, hydrogen, and oxygen, or else of the preceding elements together with nitrogen, and have received particular designations derived in general from the names of the plants by which they are furnished. The most common colour of the vege- table kingdom is green, but as the substance 234 DYEING AND CALICO-PRINTING. which gives rise to this colour in leaves and trees is of an unctuous nature, it cannot be easily applied to cloth: to obtain a green, the dyer generally has recourse to the admixture of a yellow with a blue co- louring matter. It is remarkable that the most vivid and brilliant of vegetable colours, namely, those of flowers and other parts of the plant exposed 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 colouring 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 colouring matters of plants which are capable of being isolated are yellow, brown, and red ; the only blue substances which have been pro- cured from plants are indigo and litmus, and no black vegetable substance, strictly speaking, has ever been isolated. As a particular class of bodies, vegetable colour- ing 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 in larger pro- portion in hot than cold water. Those which are insoluble in water generally dissolve in alcohol, ether, and fixed oils. PROPERTIES OF VEGETABLE COLOURING MATTERS. 235 In dry air, vegetable colouring matters appear to be permanent, but in humid air, and especially under the influence of the solar rays, they gradually lose colour, and become converted, by the absorption of oxygen from the air, into yellowish brown or co- lourless compounds. The ultimate action of air or oxygen on organic colouring matters in the presence of moisture, is to convert their carbon into carbonic acid, and their hydrogen into water. Solutions of organic colouring matters in water are acted on by oxygen with far greater facility than the dry co- lours. The colour of some of these bodies is changed in a very remarkable manner by the application of acids and alkalies. The blue colour of most flowers, that of the flowers of the violet, for instance, is rendered red by acids, and green by alkalies. The purple infusion obtained by boiling red cabbage in water is afiected in a similar manner; acids produce with it a lively red, and alkalies a full green. If the dried petals of the red rose are digested in spirits of wine, or hot water, they lose their colour without afibrding any, or at most only a trace of colour to the liquid. On adding a few drops of sulphuric acid, however, the liquid immediately acquires a fine red colour, and, if a slight excess of an alkali is afterwards added, it becomes green. The change from red to green may be produced indefinitely. The purple colour of litmus is rendered red by an acid, and blue, not green, by an alkali. Some animal and vegetable colouring matters must undoubtedly be regarded as neutral bodies, that is. 236 DYEING AND CALICO-PRINTING. 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 cha- racters of a weak acid, being capable of uniting with and neutralizing salifiable bases, as potash, soda, lime, magnesia, alumina, &c. This tendency to combina- tion is not confined, as some have supposed, to soluble colouring matters and insoluble bases ; but the union is more obvious in such cases, as the resulting com- pound is always insoluble, while soluble bases usually form soluble compounds with soluble colouring matters. For alumina and certain metallic peroxides, espe- cially peroxide of iron and peroxide of tin, some organic colouring matters possess an energetic at- traction. The pigments commonly called lakes are insoluble compounds of colouring matters with alumina or oxide of tin, which may be formed by mixing a solution of alum or of perchloride of tin* with the infusion of the dye-stulF, and adding after- wards an alkaline carbonate to liberate peroxide of tin or alumina: as the latter precipitates, it unites with and carries down the colouring mat- ter in solution, frequently leaving the supernatant liquid entirely colourless. The infusion of the dye- stuff is sometimes made with an alkaline liquor and mixed with a solution of alum after being filtered. In this way yellow lake is made with a decoction of turmeric, and annatto and quercitron lakes from the respective dye-stuffs. Important applications are made in dyeing and calico-printing of the attraction which exists between alumina and metallic peroxides on the one hand, and * Commonly called spirits of tin. PROPERTIES OF VEGETABLE COLOURING MATTERS. 237 organic colouring principles on the other. By first im- pregnating 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 dye-stuff, the colouring matter leaves the solution to unite with the base, forming an insoluble compound, whereby it becomes strongly attached to the tissue, and is rendered less susceptible of alteration by the air, the solar rays, and other decomposing agents. The attractive force of colouring matters for in- soluble bases has been regarded by some as a mere at- traction of surface, analogous to, if not identical with, the force of cohesion or adhesion, being the same as the attractive power by which charcoal is enabled to withdraw colouring substances from their solutions, 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 be- tween 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 solu- ble colouring matters seem to be cases of true che- mical combination, taking place in definite propor- tions, and under the influence of different degrees of attractive force for different colouring principles. Thus, alumina has a stronger attraction for the co- louring 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- 238 DYEING AND CALIGO-PRINTING. pregnated with alumina is immersed in a decoction of quercitron bark, it acquires a fast yellow colour ; if the same cloth is washed for some time and kept in a hot decoction of logwood, the alumina parts with the colouring principle of quercitron to com- bine with that of logwood, and the colour of the cloth becomes changed from yellow to purple. If the same cloth is next immersed for a few hours in a hot infusion of madder, the alumina parts with the colouring principle of logwood to unite with that of madder, the colour 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 interesting facts were com- municated to me by Mr. John Thom of the May- field print-works. By contact with chlorine, and in presence of a little moisture, the colour of most, but not all, ve- getable and animal dye-stuffs is instantly destroyed ; the organic substance is decomposed, being com- monly converted into colourless products, from which the original colour cannot be reproduced by any known process. In at least one case, however, which is that of indigo, the colour 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 colour to a buff, and not enough to destroy all colour. The rich crimson colour 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). PROPERTIES OF VEGETABLE COLOURING MATTERS. 239 In most cases of the destruction of vegetable co- lours by chlorine, the decomposition is effected, with- out doubt, through the powerful affinity of chlorine for hydrogen, which may be manifested in two ways ; 1st, in the direct abstraction of hydi'ogen from the organic substance, and 2ndly, in the decomposition of water, the hydrogen of which unites with the chlorine to form hydrochloric acid, while the oxygen of the water decomposes the colouring matter, form- ing carbonic acid with its carbon, and water with its hydrogen. Chlorine does not bleach readily in the absence of all moisture, and hydrochloric and carbonic acids may generally be discovered among the products. In a few cases, however, the bleach- ing action of chlorine simply consists in the direct combination of the chlorine with the colouring mat- ter to form a compound which is devoid of colour. Chromic acid is another powerful bleaching agent, which acts by affording oxygen to the colouring matter, becoming itself reduced to the state of green oxide of chromium. The colour of the vegetable substance is even more readily destroyed than if chlorine had been applied. Most vegetable colouring 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 cir- cumstance that the colours 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 240 DYEING AND CALICO-PRINTING. of the colouring matter, or on the union of the sul- phurous acid with the colouring matter to form a colourless combination. Charcoal has also been classed among bleaching agents, as it readily withdraws colouring matters from their solutions, frequently leaving the super- natant liquid entirely colourless. The charcoal which absorbs colouring 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 colouring matter is not decomposed, but is merely mechanically attached to the surface of the charcoal, without having experienced any chemical alteration whatever. Wlien brought into contact with deoxidizing agents, several organic colouring matters part with a portion of their oxygen, and at the same time lose their colour. But if afterwards exposed to the air, or any source of free oxygen, the deoxidized bodies re- assume oxygen, and with that element their original colour. The coloured bodies would therefore appear to. be compounds of oxygen with a colourless radical. The alternate reduction and oxidation may be prac- tised on the same substance indefinitely. As ex- amples of colouring matters susceptible of these changes, may be mentioned litmus, logwood, Brazil- wood, sapanwood, peachwood, red beet-root, and the red cabbage. The most convenient deoxidizing agents to be employed in such experiments are the following : TROPERTIES OF VEGETABLE COLOURING MATTERS. 241 1°. A mixture of granulated or feathered tin and a caustic alkali. 2°. 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 colouring 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 coloured infusion, or the latter may be agitated in a jar containing the gas. As the colour 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 colourless or white radicals of Brazil-wood, logwood, sapanwood, &c. do not unite with alumina and metallic peroxides to form insoluble compounds or lakes, like their oxides, or the true colouring matters. Other vegetable colouring principles than those above mentioned become converted into colourless 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 in- stead of the yielding up of oxygen. When exposed to the air or other source of free oxygen, this .hydrogen is removed, and the original colour returns. Indigo is one of the colouring matters susceptible of such changes. Several colouring principles are contained in the plants from which they are derived in their white, R 242 DYEING AND CALICO-PRINTING. deoxidized, or hydruretted state. Sucli is the case, for example, with indigo. That substance does not exist in the blue or dehydruretted state in the plant by which it is furnished, but as white indigo, or indi- gotin, the colourless hydruret of indigo-blue. Most vegetable juices, the recent pulp of fruits, detached leaves, &c. become coloured brown and yellow by exposure 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 colour. Colouring 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 colour so completely as to leave the liquid colourless, as if animal charcoal had been introduced. The affinity of vegetable tissues for colouring matters is in general not so great as that of animal tissues for the same substances. The vegetable fibre readily combines with a colouring material ; 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 colouring matters is presented in the stain- ing of a linen napkin by red wine. The portion of the cloth on which the wine falls soon abstracts the whole colour from the liquid, becoming dyed red ; but beyond the spot thus produced, the cloth be- comes moist Avithout acquiring an appreciable colour, the wine having been deprived of all its colour by PROPERTIES OF VEGETABLE COLOURING MATTERS. 243 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 colouring mat- ters, as many mineral substances are withdrawn from their solutions by tissues in quite a similar manner. Thus, cotton cloth readily separates lime from lime-water,* and the insoluble sulphate of alu- mina from an aqueous solution of basic alum. Vegetable and animal colouring principles are di- visible into two classes, with reference to their so- lubility 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 as- sistance 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 colouring matter. Those colouring matters which are of themselves insoluble, or but slightly soluble in water, generally form, as might be ex- pected, much faster combinations with tissues. In- digo, annotta, safllower, and such yellow and brown dyes as contain tannin combined with substances of the nature of apotheme, are the principal members * The separation of lime from lime-water by cotton cloth is ex- hibited when a drop of a solution of bleaching powder (which always contains free lime) is allowed to fall on a piece of cotton dyed with in- digo. On the spot where the solution first touches the cloth, the colour remains unaltered, the lime only having been there intimately absorbed ; but on the ring surrounding this spot, the colour becomes discharged through the action of the chloride of lime. k 2 244 DYEING AND CALICO-PRINTING. of tliis class. To effect tlieir solution, some other solvent than pure water must be applied. Thus, indigo is dissolved by bringing it, through the ac- tion 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 dipped into such a solution, the white indigo is absorbed into the pores of the fibres, and on ex- posing the cloth to the air, imbibes oxygen, by which it becomes converted into the original insoluble in- digo blue. The latter remains firmly attached to the fibre, being imprisoned within the pores, and there- fore incapable of being removed by mere washing in water. The colouring matters of annotta and safiiower, 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 co- lours, by first impregnating it with the alkaline in- fusion 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 safflower is by wincing the piece in an imperfectly neutralized alkaline infusion of the dye-stuff*, which contains the colouring matter in a state of feeble suspension, readily precipitated on a solid body presenting a finely di- vided surface, such as cloth. The partial neutra- lization of the alkali in this process is effected by a very weak acid or an acidulous salt, such as bitar- trate of potash (cream of tartar). Such are the principal general properties of or- ganic colouring principles, a knowledge of which is NATURE OE COLOUR. 245 of the highest importance to the practical dyer and calico-printer. But these bodies dilFer so much from each other in many respects, 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 general pro- perties of each distinct colouring matter separately. Nature of colour. — The appearance of colour 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 colours, red, yellow, and blue. As a mixture or combination of these three coloured rays, white or colourless light may be considered, the absence of colour depending on the exact equilibrium of the three. When the coloured rays are partially separated by the refractive force of a glass prism, an image or spectrum is obtained, presenting seven different colours, namely, red, orange, yellow, green, blue, indigo, and violet. The orange, green, indigo, and violet tints proceed from the intermixture in various proportions of the three primary rays. Among opaque substances, there are some which completely absorb the three coloured rays incident on their surface, and therefore, having no light to reflect to the eye, appear hlach. Others, on the contrary, reflect all the light, and are consequently white. But others possess the power of decom- posing the light, that is, of absorbing the whole or a portion of one of the three primary rays and re- 246 DYEING AND CALICO-PRINTING. fleeting the remainder; or, it may be, of absorbing unequal proportions of each of the three rays. When such is the case, the body appears to be coloured, not from the inherent possession of a colour, but because the light which it reflects to the eye is not homogeneous white light. A blue substance, for ex- ample, is said to reflect the blue rays only, or in greatest proportion, 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 re- flection of more or less of the white or undecomposed light, every shade of colour may be produced. The same remarks apply to transparent coloured substances ; only, instead of the decomposed light being reflected to the eye, it is transmitted. According to this manner of viewing the colouring principle, it has been observed that the art of dyeing consists in fixing upon stuffs, by means of molecular attraction, substances which act upon light in a manner dif- ferent from the stuffs themselves. The production of white by the combination of the three primary colours is practised in one of the finish- ing operations to which goods are subjected in the process of bleaching. To whatever length the or- dinary 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, indigo, archil, or a mixture of Prussian-blue and cochineal pink. In such cases the blue, or mixture of blue and pink, supplies the tints necessary to the production of white with the brownish-yellow colour of the goods. But when the LIST OF VEGETABLE COLOURING MATTERS. 247 dyer attempts to form white by combining red, yel- low, stnd blue, he often obtains a dark brown, or black, because the resulting combination does not reflect as much light as the three coloured ingredients separately. The following alphabetical list of colouring mat- ters, with their origin, uses, and principal chemical characters, may prove useful for reference. The history and applications of some of them will be fully discussed in separate articles. I. LIST OF VEGETABLE AND ANIMAL COLOURING MATTERS. Alkanet. — The root of the Anchusa tinctoria. Its colouring principle, which is red, is nearly in- soluble in water, but soluble in alcohol, ether, oil of turpentine, and fixed oils. It is used as a colour- ing matter for ointments and other unctuous pre- parations, but not in dyeing. A variety of alkanet was formerly met with in commerce, derived from the roots of the Lawsonia inermis. Annotta. — A hard paste prepared by inspissating the washings from the fermented seeds of the Bixa orellana. Its colouring matter is yellowish-red, nearly insoluble in water, soluble in alcohol and al- kaline liquids. It forms an orange-coloured com- pound with alumina, a citron-yellow compound with protoxide of tin, and a greenish-yeUow compound with protoxide of copper. It is used to dye silks golden-yellow, by simply digesting the goods in an 248 DYEING AND CALICO-PRINTING. alkaline solution of annotta, and orange-red by ex- posing them afterwards to tlie action of a dilute acid. It is also used to dye cotton yellow, with the aluminate of potash as the mordant, and as a colour- ing matter for cheese. Archil. — A violet-coloured paste, made from dif- ferent species of lichens : that 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 modi- fications of archil. The colouring principle of these dye-stuffs is soluble in water and alcohol, and its colour is changed by the weakest acids from purple or violet to bright red. It is a brilliant colour, but possesses 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 colours. It is rarely used for cotton goods. Barwood. — This is a dull red dye-stuff, the colour- ing 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 facility. It gives red com- pounds with alumina and peroxide of tin, and is mostly used for dyeing silks and woollen cloth. The colouring matter of camwood is quite similar in its properties to that of barwood, but is somewhat brighter in colour. Both barwood and camwood possess much more permanence than peachwood, for which they are now frequently used as substitutes. Brazil-wood. — This and Sapanwood^ Fernam- houc-wood^ Peachwood, and Nicaragua-wood, are derived from certain species of Cesalpina. Their LIST OF VEGETABLE COLOURING MATTERS. 249 colouring 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- coloured compound with peroxide of tin. It is of itself a fugitive colour, being easily bleached by light with exposure to the air ; but its stability is consi- derably 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. Camwood. — (See Barwood.) 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 matter. It gives a rich brown-grey colour 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-printing as a topical brown, when mixed with nitrate, sulphate, or acetate of copper, and sal-ammoniac. Cochineal. — A female insect found on the cactus opuntia or nopal ^ dried. Its colouring principle, termed coccinellin, is naturally of a purplish-red 250 DYEING AND CALICO-PRINTING. colour ; it is soluble in water and weak alcohol ; its colour 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 means of a mixture of decoction of cochineal with cream of tartar and dyers' spirit, which is a mixture of pro- tochloride 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 irtfec- torius. The berries afibrd a bright yellow liquid when boiled in water, which gives a golden-yellow colour 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 colour when combined with a tin or aluminous mordant. Fustet or yellow fustic. — The wood of the rhus cotinus, the colouring matter of which is yellow. Being a fugitive dye-stulF, it is very little employed at present in dyeing processes. Fustic or old fustic. — The wood of the morus tinctoria. Its aqueous decoction is orange-coloured, 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 tint with copperas. LIST OF VEGETABLE COLOURING MATTERS. 251 Indigo. — A blue insoluble pigment procured by the oxidation of a colourless substance (indigotin) contained in tlie leaves of the indigofera, by sub- jecting the leaves to a process of fermentation. In- digo blue may be reconverted to indigotin by apply- ing a deoxidizing agent, and then becomes soluble in alkaline liquids, in which form it may be applied to cloth (see page 244). Kermes grains. — Dried female insects of the species coccus ilicis, which are found on the leaves of the quercus ilex or prickly oak. The decoction of kermes in water 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 colouring matter quite similar to that of cochineal. Lac-dye is the residue of the evaporation of the aqueous in- fusion of ground stick-lac. It is employed to dye wool of a brilliant scarlet colour with a mordant of dyers' spirit. The solution of the lac for this pur- pose is effected in very dilute muriatic acid. Litmus. — (See Archil.) Logwood. — (Campeachy wood.) — The wood of the hcBmatoxylon campechianum. Though the colour- ing 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, afford- ing a reddish liquid, which is rendered purple by 2 DYEING AND CALICO-PRINTING. alkalies, 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 rubia peregrina. According to M. Runge, madder contains five distinct colouring 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 cannot be employed in a concentrated solution. It is very extensively used in the dyeing and printing of cotton goods for the production of a permanent bright red colour 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 colouring matter than the natural root is now met with in commerce, under the name of gamncine. 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 colouring matter un- altered. Nicaragua-wood. — ( See Brazil-wood. ) Peachwood. — (See Brazil-wood.) Quercitron — The bark of the quercus nigra, or LIST OF VEGETABLE COLOURING MATTERS. 253 yellow oak, which grows in North America. Its colouring principle, which is yellow, is very soluble in water. Quercitron is much used to impart a yellow colour to cotton with the intervention of an aluminous mordant, and to produce drabs with an iron mordant, 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. Saffiower. — The flowers of the carthamus tinc- torius. Safflower contains two colouring 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 colour by wincing the piece in an imperfectly neutralized alka- line infusion of the dye-stuff. Sandal-wood. (Red Sanders wood.) — The wood of the pterocarpus santalinus. Its colouring matter is red, scarcely soluble in water, but soluble in alka- line lyes. The colour may be applied to tissues by dipping them alternately in an alkaline decoction of sandal-wood and in some acidulous liquid. It 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 colour to black, with peroxide of iron as the mordant. These matters can hardly be classed among colouring matters, as their active ingredients, tannic and gallic acids, are white when pure. By uniting with per- oxide of iron, however, these acids form blueish- 254 DYEING AND CALICO-PRINTING. black compounds, whicli 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 afterwards digesting it in a solution of copperas. An infusion of logwood is commonly added to the solution of copperas. Vegetable astringent principles are also used in some other dyeing pro- cesses, in which their action seems to partake of that of a mordant. Turmeric. — The root of the curcuma longa. Its colouring 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 luteola. 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 per- oxide of tin as the mordant. With the latter, weld affords to cloth the fastest vegetable yellow colour we possess. Woad. — The colouring 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 COLOURS 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 afterwards exposing LIST OF MINERAL COLOURING MATTERS. 255 it to the air to precipitate the sulphuret, through the absorption of carbonic acid. Arseniate of chromium. — This is a fine grass- green coloured compound, which may be imparted to cloth, by the application, first of a solution of chlo- ride of chromium, and afterwards of a solution of arseniate of soda. Chrome-yellow^ or chromate of lead. — The co- lour of this pigment is bright yellow; it may be communicated to cloth by the consecutive applica- tion of solutions of acetate or nitrate of lead and bi- chromate of potash ; or the oxide of lead may be first fixed on the cloth in an insoluble state, as carbonate, tartrate, or sulphate. It consists of one equivalent of chromic acid and one equivalent of oxide of lead. Chrome-orange^ or suhchromate of lead. — This is a dark orange-red pigment, consisting of one equi- valent 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 afterwards passed through hot milk of lime, by which a portion of the chromic acid of the chrome-yellow is separated. Manganese hrown {hydrated peroxide of 7nan- ganese). — Cloth is dyed with this substance by being passed, first, through a solution of sulphate or chlo- ride of manganese; next, through a caustic alkaline solution, to precipitate protoxide 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 communi- , 56 DYEING AND CALICO-PRINTING. cated to silk, wool, and cotton, by first passing the goods through a solution of orpiment in ammonia, and afterwards suspending them in a warm atmo- sphere 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 afterwards effected by passing the cloth through dilute sulphuric acid. Peroxide of iron {iron huff). — 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 alkaline carbonate, in succession. Prussiate of copper. — A delicate cinnamon colour is sometimes communicated to cotton by means of this substance, which is applied by first passing the cloth through a solution of sulphate of copper, then through a dilute alkali to precipitate oxide of cop- per, and lastly, wincing in a solution of yellow prussiate 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 afterwards passed through a solution of yellow prussiate of potash, acidified with a little muriatic acid. Sclieele^ s green {arsenite of copper). — This grass- green coloured substance may be applied to cloth by the double decomposition of nitrate of copper and arsenite of potash ; the cloth being passed through solutions of these salts consecutively. A better me- thod is, first to precipitate oxide of copper on the cloth by the action of an alkali, and to wince the piece afterwards in a solution of arsenite of potash. GENERAL NATURE OF DYEING PROCESSES. 257 § III. GENERAL NATURE OF DYEING PROCESSES. The processes by which different kinds of textile fabrics are impregnated with the same colouring ma- terial are often very dissimilar, and few dyeing pro- cesses are applicable in their details to goods of cot- ton, silk, and wool. For this reason, the observa- tions in the present section refer chiefly to cotton fa- brics, the treatment of which requires greater assist- ance 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, whether the cloth is merely dyed and finished in that state, or both printed and dyed.* The object of the ^^s- 3Q. first operation to which cotton goods are subjected, whe- ther intended to be afterwards printed or merely dyed, is the removal of the fi- brous down or nap on the surface of the cloth. This is efiected by the process of singeing, which may be performed in two different ways equally efficaci- * For detailed accounts of distinct dyeing processes, the reader is referred to other articles treating of individual colouring materials. S 258 DYEING AND CALICO-PRINTING. ous. 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 flue of a fire-place, situated immediately at one end of the bar. The disposi- tion of the different parts of a singeing furnace may be understood with the assistance of the sectional representation in fig. 30 ; a represents the fire-place, and b the ash-pit ; c is the semi-cylindrical bar of cop- per, 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, to cool from the efiects of singeing. In the figure, the flue is represented as passing downwards to com- municate with the common draught-chimney. An iron bar, of two inches or more in thickness at the top, was formerly 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 con- sumption of fuel. With a copper bar, about fifteen hundred pieces may be singed by a ton of coals in a well arranged furnace. The cotton 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." By this operation the colour of the calico becomes very similar to nankeen. The other method of singeing consists, in passing the cloth rapidly through a coal-gas flame, for which a patent was obtained by Mr. Hall of Basford, near Nottingham, in the year 1818. The gas issues from numerous perforations through the upper surface of GENERAL NATURE OF DYEING PROCESSES. 259 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 suflicient to draw the flame through immediately, an improvement in the apparatus was devised by Mr. Hall, and patented in 1823, which consisted in placing immediately over the gas-flame a horizontal tube, with a slit lengthways through its lower surface, which tube is placed in communication with a fan or an exhausting apparatus. An arrange- ment 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. That the colours 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 na- turally adherent to the fibre of the cloth. In cotton goods, this is accomplished by the process of bleach- ing by means of chlorine ; and in silk and woollen goods, by the action of sulphurous acid. The ordinary operations practised in the process of bleaching by chlorine consist in subjecting the cloth to the successive action, 1°, of a dilute al- kaline solution ; 2°, of a dilute solution of chloride of lime or bleaching powder (commonly called " che- mic" in bleach-works and print-works); and 3", of dilute sulphuric acid. The operation of submitting 260 DYEING AND CALICO-PRINTING. the cloth to a solution of bleaching powder is known as " chemicking ;" and to dilute sulphuric acid, as " souring." The action of sulphuric acid on the cloth impregnated with a solution of bleach- ing powder is to liberate chlorine by combining with the lime to form sulphate. The details of this important process will form the subject of another article ; for the present, the following list of the successive operations to which a cotton fabric is sub- jected in order to prepare it for printing, will suffice for purposes of reference : 1. Washing in cold water, 2. Soaking for eight hours in boiling lime-water, 3. Washing in cold water, 4. Souring, 5. Washing, 6. Soaking for ten 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 GENERAL NATURE OF DYEING PROCESSES. 261 soap, and soda, at about the temperature 130° Fahr., and then exposed for several hours to the action of sulphurous acid gas, produced from burn- ing sulphur in a close chamber. The latter ope- ration is termed " sulphuring." The goods are next passed through a very weak solution of caustic soda, dried, and usually impregnated with a dilute solu- tion of tin, which imparts considerable brilliancy to the colours afterwards applied to the goods. For this purpose, de laines (which are formed of cotton and wool) are impregnated with two different solu- tions 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 perchloride of tin and muriatic acid, for the wool; the other is stannate of potash,* from which oxide of tin is preci- pitated on the cotton by passing the piece afterwards 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 sub- jected 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 es- sential that the colouring material, or the substances from which it is to be produced, should be applied in a state of 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 * A solution of oxide of tin in caustic potash. 262 DYEING AND CALICO-PRINTING. piece of cloth is dipped into common writing-ink, the black colour acquired by the cloth may be removed by washing with water, because the tannate of iron, which is the basis of the ink, instead of be- ing 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 necessary to pro- duce it within the jibre^ which is accomplished by first imbuing the cloth with an infusion of galls or other liquid containing tannin, and afterwards with a solution of a salt of iron. That the colours 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 colours rests ; and the more insoluble the compound in other liquids, so much the faster the colour. In nearly all the different processes for dyeing cloths, the colour is applied by one of the four fol- lowing methods : 1. From two solutions ; the colouring material not existing in either separately, but produced on the mixture of the two. The cloth is first impregnated with one solution, and afterwards with the other. 2. From the solution of the colouring material ; the cloth being first impregnated with some sub- stance (usually existing on the cloth in the solid state), which has the property of combining with the colouring matter to form an insoluble com- pound. 3. From the solution of the colouring material GENERAL NATURE OF DYEING PROCESSES. 263 itself, or its basis; the cloth having previously un- dergone no essential preparation. 4. By effecting a chemical alteration of the fibre of the cloth, with the formation of a coloured pro- duct. By the first method of dyeing, which is the sim- plest and most intelligible, all mineral colours, such as chrome-yellow, Prussian-blue, peroxide of iron (iron buff), and manganese-brown, may be applied to textile fabrics. The proper colouring 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 pot- ash is mixed with an aqueous solution of acetate of lead, an insoluble precipitate of chrome-yellow (chro- mate of lead) is produced. In like manner, Prus- sian-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 colours, the mixture of the proper 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 fast- ness of colours applied to cloth in this way is en- tirely a mechanical effect, and in no way referable to a chemical attraction of the fibre for the colouring matter. A piece of white cotton cloth moistened with either 264 DYEING AND CALICO-PRINTING. a solution of bichromate of potash or of acetate of lead, may be easily cleaned from every particle 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 afterwards 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 by washing with water. The chrome-yellow that is washed away in this experiment was merely loosely attached to the exterior of the fibre. It may be observed here, that as all the colouring 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, squeezing, and sometimes by slightly wash- ing the cloth when taken out of the fii'st solution and about to be immersed in the second. So far as the mere operations are concerned, the processes now commonly practised for applying mi- neral colours to cloth, are rather referable to the second style of dyeing according to the classification here adopted. Instead of passing the cloth through the two solutions consecutively, one of the two ma- terials, usually the base of the mineral colouring matter, is first applied in an insoluble state, and the cloth is afterwards winced or agitated in a dilute solution of the other. To 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 passing the cloth through GENERAL NATURE OF DYEING PROCESSES. 265 a dilute alkaline solution ; and the prussiate of cop- per is formed, lastly, by wincing the cloth in a dilute solution of yellow prussiate of potash contain- ing 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 apply- ing the two solutions in succession, without the fixa- tion of a substance derived from the first ; since the production of any superfluous colouring material is en- tirely avoided. In the process of dyeing cotton with chrome-yellow, the same depth of colour may be im- parted to a piece containing precipitated oxide or carbonate of lead, from a solution of eight ounces of bichromate 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 ob- served, that although the mere operations in this kind of work are the same as those of the second style to be noticed immediately, yet the principles of the two styles are dissimilar, for the colouring material is not contained in the second solution any more than in the first. To apply to cloth in a permanent manner those colouring substances which are naturally soluble in water, and have not in themselves a strong afiinity for tissues (see page 243), of which kind are the greater number of vegetable and animal tinctorial matters, it is essentially necessary to effect their con- version on the cloth into compounds which are in- soluble in water. This is accomplished by first ap- plying to the cloth some substance (most frequently 266 DYEING AND CALICO-PRINTING. I the sub-salt of a metallic oxide) whicli has an affinity for the colouring 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 colouring matter, is distinguished as the mordant. One 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 colouring matter, except in some cases where both may be applied at the same time ; but with mineral colours, which may be imparted by the successive application of two solu- tions, it is generally a matter of indifference which of the two solutions the cloth is first impregnated with. In its common acceptation by the practical dyer the term mordant is as indefinite as it is inappro- priate, since it includes any kind of substance which can facilitate the application of a dye-stuff to a tissue. Properly speaking, a mordant is a substance which has an attraction of surface for the tissue, a chemical affinity for the colouring matter in solution (see page 236), and the property of forming an insoluble compound with the colouring matter. By virtue of the combination of these properties, it is enabled to effect in a durable manner the union of the tissue with the colouring substance. But with the practical dyer, the term mordant has a much wider signification ; even the solvent of the dye-stuff, if the latter is insoluble in water, re- ceives that designation; thus sulphuric acid is some- times 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 GENERAL NATURE OF DYEING PROCESSES. 267 time when little was known respecting the chemical principles of dyeing, is derived from mordere, 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 colour. In most cases of cotton dyeing with the inter- vention of a mordant, the latter 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 pene- trate to the interior of the fibre. The cloth, there- fore, 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 (con- sisting of an acid and a base), in which the pro- portion of base is in considerable excess. When a piece of cotton, for example, is moistened with a solution of basic alum (soluble subsulphate of alu- mina) and dried, an insoluble subsulphate 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 mor- danted is immersed in the dye-beck, the insoluble sub-salt combines as such with the colouring matter in solution; the combination, which is doubtless a chemical one, takes place between the colouring matter and the base of the sub-salt. In this case. 268 UYEmG AND CALICO-PRINTING. either all the acid of the sub-salt or else the corre- sponding soluble neutral salt is liberated and dissolved, the whole or the excess of base remaining on the cloth to fix the colouring material. When a piece of cotton impregnated with sub- sulphate of alumina, for example, is put into the madder-beck, the colouring matter of the madder combines 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 in 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 soluble and neutral sulphate on the other. From the preceding observations may be inferred the necessity of distinguishing between the three states in which a mordant may exist ; namely, first, in the soluble form in which it is applied to the cloth ; second, as the insoluble sub-salt afterwards produced in the fibre; and third, as the true base existing in union with the colouring matter in the dyed cloth. The term mordant ought strictly to be confined to the true base, in whatever form it exists; but for convenience, it is also applied to the first solution, and to the sub-salt on the cloth before the dyeing. In a few cases, however, the insoluble substance which is precipitated on the cloth from the solution of the mordant is not a sub-salt, but the true mor- dant or base itself; thus, pure alumina may be pre- cipitated from the solution of aluminate of potash, and pure peroxide of tin from the solution of staimate of potash. GENERAL NATURE OF DYEING PROCESSES. 269 If the affinity of the colouring matter for the mor- dant is so powerful that a compound of the two is precipitated immediately on their solutions being placed in contact, the intermediate step, consisting in the formation of the insoluble sub-salt by drying, is sometimes omitted. The cloth is then first impreg- nated with the solution of the mordant, and after being washed, drained, and squeezed, is passed through the solution of the colouring matter. It frequently happens, however, and especially with wool and silk, that even in these cases an in- soluble sub-salt does attach itself to the fibre from the solution ; but it is commonly produced on cotton during the desiccation of the mordanted goods. In all cases where the formation of an insoluble sub- salt by the desiccation of the mordant on the cloth is omitted, the excess of mordant which remains on the surface of the cloth is removed by washing and draining, before the cloth is exposed to the dyeing liquid. This excess of mordant is removed for three reasons ; 1°, to prevent an unnecessary abstraction of colouring matter from the dye-beck ; 2°, to ensure a more uniform distribution of tint ; and 3°, to attach the colour in a more permanent manner. When the solution of the mordant produces an immediate pre- cipitate with that of the colouring matter, if the ex- cess of mordant is allowed to remain on the cloth, the latter assumes a good colour when put into the dye- beck, but which is, for the most part, merely at- tached to the surface, very little existing in the interior of the fibre. This seems to arise from the closing of the apertures through which a liquid ob- 270 DYEING AND CALICO-PRINTING. tains access to the interior of the tube or cell, by the precipitate of colouring matter. But the colour which results when the washed and drained cloth is put into the dye-beck, is often devoid of lustre and very subject to alteration, ap- parently, because the quantity of mordant on the cloth is too small to form an intimate combination with all the colour which is deposited. On apply- ing, however, either the same mordant a second time, or else another mordant, the brilliancy of the tint is greatly increased, and the colouring material becomes permanently attached. The second mor- dant which is applied in this manner is known among dyers by the name of alterant, proposed by Dr. Bancroft. A particular example will render such a process more intelligible. If a piece of white cotton cloth is transferred at once from a dilute solution of perchloride of tin to a weak decoction of log- wood, the cloth assumes an uneven violet colour, feebly attached and removable by washing. But if the perchloride remaining on the surface is tho- roughly removed before the cloth is put into the decoction, the piece assumes a dull brownish violet tint ; by properly adjusting the strength of the so- lution of perchloride to that of the decoction, the latter may be entirely deprived of colour. If, in the next place, a small quantity of a solution of per- chloride of tin, or acetate of alumina, is added to the liquor as an alterant, the cloth acquires a good violet or purple colour, and is now permanently dyed. The most probable explanation of the action of the alterant in such a case as the above, is the GENERAL NATURE OF DYEING PROCESSES. 271 following. With a proper proportion of the co- louring matter of logwood, peroxide of tin forms a compound possessed of a lively colour, which com- pound is capable of uniting loosely with more of the colouring matter of logwood, the proper tint of which, by itself, is red. The colouring matter in excess does not partake of the lively violet or pur- ple tint, of what may be considered as the neutral compound with the mordant, but the effect of apply- ing more mordant (as the alterant) is obviously to form a neutral compound with the excess of co- louring matter possessing the proper violet or pur- ple colour. If the decoction of logwood to which the mordanted and washed cloth is exposed, is mixed with a very small quantity of a free acid, the pre- cipitation of an excess of colouring matter is pre- vented (partly, it would seem, through the solvent power of the acid); so that the cloth assumes a lively colour at once, and the application of an alterant is unnecessary. It is not essential to the character of an alterant that its action partake of that of a mordant. Thus, instead of mixing a free acid with the decoction of logwood, the acid may be afterwards applied to the dyed cloth, in which case it becomes the alterant, partly by removing some of the colouring matter in excess, and partly by disintegrating the particles of the mordant, whereby the latter is enabled to form a more intimate combination with the colouring matter. In an extended sense, the term alterant may be applied to any substance which can effect a perma- nent change in the colour of a dyed cloth, whatever may be its chemical action. Thus, oxalic acid be- 272 DYEING AND CALICO-PRINTING. comes an alterant when applied to the purple woollen cloth obtained by cochineal with a mordant of prot- oxide of tin, whereby the purple becomes changed to scarlet ; bichromate of potash may also be called an alterant when applied to a piece of cotton dyed violet with logwood and alumina, in order to change the violet into a black. In a few cases, where the affinity of the colouring matter for a mordant is not sufficiently strong for the former to separate, by itself, the mordant from the substance with which it is already in combina- tion, the solution of the mordant and that of the colouring material may be mixed without the forma- tion of a precipitate. Thus, no precipitate of colour- ing matter and mordant ensues when the soluble combination of alumina and caustic potash (alumi- nate of potash) is mixed with a solution of the co- louring matter of annatto; nor when a solution of protochloride of tin is added to a cold decoction of logwood. When this is the case, the cloth is not always first impregnated with the mordant and af- terwards with the colouring matter, but both may be applied at once by exposing the cloth to the mix- ture previously made. So far as the mere operation is concerned, however, this style of dyeing differs from that we have been considering, being referable to the third style according to the division followed in this section (page 262) ; but the function of the mor- dant and its action on the dye are of precisely the same nature as when the mordant is first applied, excepting that the formation of the insoluble com- pound of mordant and colouring principle which GENERAL NATURE OF DYEING PROCESSES. 273 attaches itself to the fibre, appears here to be partly determined, as an induced effect, by the surface at- traction of the tissue for the resulting compound. A similar effect may be produced in the above mixture of protochloride of tin and decoction of logwood by the application of heat, which seems to increase the mutual afiinity of the mordant and colouring principle. The cloth does not in such cases abstract the whole of the colouring matter from the dyeing liquor, but the depth of its colour corresponds, in general, to the strength of the infusion, the temperature, and the time during which it is exposed to the mixed liquid. Vegetable colouring matters are not often applied to goods of cotton by this style of dyeing except as steam colours, where the mixed solution of mordant and colouring matter is printed on the cloth, and the fixation afterwards effected by exposure to steam. The principal colouring principles thus applied are those of logwood, French berries, cochineal, peachwood, and quercitron, with a tin or aluminous mordant: an orange colour is sometimes imparted to cotton by means of the mixture of annatto and alumina in caustic potash, applied as above. It rarely happens that the common aluminous mor- dants, such as basic alum and red liquor, can be employed alone as mordants for vegetable colouring matters when applied as steam or topical colours, on account of the facility with which the alumina is precipitated by the vegetable decoctions. But this tendency to precipitation may be greatly diminished by applying to the alumina a more powerful solvent. Thus, the solutions of alumina commonly employed with logwood, &c., when applied as steam colours. 274 DYEING AND CALICO-PRINTING. are basic alum mixed with oxalic or another strong acid, red liquor mixed with oxalic acid, and common alum mixed with sugar. As the combination of the colouring principle with the mordant is to be considered a case of true che- mical union, it might be anticipated that the colour- ing matter often experiences a considerable modifica- tion in tint on uniting with a mordant, independent of the colour possessed by the mordant itself, con- sistently with the law that a change of properties always attends chemical combination. Such a change in colour is certainly often exhibited, but sometimes the colour of the resulting compound is intermediate between that of the colouring matter and that of the mordant; and the colour of the dye-liquor may ge- nerally be imparted to a tissue without much altera- tion by the use of a white mordant. If a piece of cloth is impregnated with alumina and then passed through the madder-beck, it ac- quires a rose tint; in the same dye-beck, but with peroxide of iron as the mordant, the cloth becomes dark brown or even black; and with a mixture of alumina and peroxide of iron, a puce colour may be obtained. If three pieces of cotton, one impregnated with alumina, another with peroxide of iron, and the other with oxide of copper, are passed through a decoction of quercitron, the piece containing alu- mina presents very nearly the proper yellow of the dye ; that with oxide of iron has a dark fawn colour, and that with oxide of copper a yellowish fawn colour. Cochineal produces a purple compound with a mordant of protoxide of tin, which is itself white; GENERAL NATURE OF DYEING PROCESSES. 275 but a scarlet compound with peroxide of tin, which is also white. The quantity of the colouring matter absorbed by the mordanted cloth is, in general, proportional to the quantity of mordant it contains, which may be deter- mined by the strength of the solution of the mordant. Hence two pieces of cloth impregnated with solutions of the same mordant of unequal strength would pre- sent very different depths of colour by being passed through the same dye-beck. With the acetate of iron as a mordant, the same infusion of madder may be made to afford any variety of tint between faint lilac and black, and with an aluminous mordant any shade between the most delicate pink and dark red. The class of bodies from which mordants are de- rived is the metallic oxides or bases, whence they might be supposed as numerous as metals which form insoluble oxides; but so many qualifications are re- quired in a mordant, besides insolubility, that their number is very limited. Those most commonly em- ployed are alumina, peroxide of iron, peroxide of tin, and protoxide of tin. The chemical affinity of these bases for colouring matters has already been alluded to (page 237); and many of their salts, or compounds with acids, have likewise a considera- ble attraction of surface for the stuffs, so that the latter have the power of withdrawing them to a cer- tain extent from their solutions. These bases also possess a property which seems often to be highly advantageous, namely, that of forming with the same acid, when united with it in different proportions, a soluble and an insoluble combination. 276 DYEING AND CALICO-PRINTING. Alumina,* which is the most extensively employed of the mordants, may be applied to cloths from four different solutions; 1°, from ordinary alum, which is a double salt composed of sulphate of alumina and sulphate of potash; 2°, from the solution of sub- sulphate of alumina, also known as basic alum, which is merely common alum with a portion of its acid neutralized by an alkali; 3*', from red liquor, which is commonly a solution in acetic acid of the subsul- phate of alumina insoluble in water ; and 4°, from a solution of alumina in caustic potash, known as the aluminate of potash. From alum, from the soluble subsulphate of alumina, and from common red liquor an insoluble subsulphate is produced on the cloth containing less sulphuric acid than the soluble sub- sulphate; and alumina itself is deposited from the aluminate of potash. 1. Alum. — This salt, in its ordinary state, is not much employed at present in cotton dyeing, being superseded by basic alum, red liquor, and the alu- minate of potash ; but it is still extensively used in silk dyeing and printing, and is the principal mor- dant used in the dyeing of wool. On cotton goods common alum is sometimes employed as the mor- dant for topical and steam colours, where the alu- * This earth is thrown down as a white bulky precipitate when a solution of alum is mixed with an excess of ammonia. It is not ob- tained pure, however, by such a process, but retains some of the sul- phuric acid. To prepare pure alumina, the precipitate as thus obtained may be redissolved in dilute sulphuric acid and again precipitated by ammonia. The proper neutral sulphate of alumina is very soluble in water and difficult to crystallize ; by the addition of sulphate of potash it becomes common alum, which is much less soluble and very easily crystallized. ALUMINOUS MORDANTS. 277 mina is required to be held in solution pretty strongly. The chemical constitution and properties of alum will form the subject of a future paper. The impurity which common alum is likely to contain of greatest moment to the practical dyer is iron^ existing in the state of sulphate (usually, both of the peroxide and protoxide), and chloride. It is derived from the mother-liquor from which the alum was crystallized. The readiest method of detecting this impurity is by adding to the aqueous solution of alum a few drops of a solution of yellow or red prussiate of potash, which cause the formation of a precipitate of Prussian blue with a very small trace of iron. The preci- pitate at first produced with the yellow prussiate is generally greenish-white, but becomes blue on ex- posing the mixture to the air for a few minutes. In this case the iron is present in the alum in the state 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 so- lution 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 applying 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 colour to be produced. In most cases, where the entire surface is to be impregnated with the colouring material, the goods may be allowed to remain for twenty-four hours, or more, in a cold 278 DYEING AND CALICO-PRINTING. 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 so- lution of three or four parts of alum to ten or twelve parts of silk and one hundred of water. Wool may be impregnated with alum by heating it in a solution containing 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 ebulli- tion for two hours is prejudicial. A very common addition to alum when employed as a mordant, espe- cially 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 colour. The quantity which is added varies for different dye- stuffs from one-fourth to one-half of the weight of the alum. When employed as a mordant for topical or steam colours, a quantity of sugar is usually added to the alum. 2. Basic 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 separat- ing 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 common alum is sufficient to retain in solution all the alumina of the alum, provided the liquid is cold and in a concen- ALUMINOUS MORDANTS. 279 trated state. The partial separation of the acid may- be effected 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 addition 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 insoluble sub- sulphate 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 pro- duced when chalk is digested in a solution of common alum, sulphate of lime being then formed. According 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 nine- teen parts of cold water for its solution. A solution of basic alum prepared by an alkaline carbonate, as above, cannot be well employed ex- cept in a concentrated state, as mere dilution with water determines the formation of a precipitate of insoluble subsulphate of alumina. But this incon- venience may be overcome, and an excellent mor- dant obtained, by adding acetic acid to the solution of basic alum. The mixture thus formed, which is * 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 with agitation. 280 DYEING AND CALICO-PRINTING. quite analogous to common red liquor, affords no pre- cipitate on dilution with water. 3. Red liquor and acetate of alumina. — Red liquor is much more extensively employed as a mor- dant than any other preparation of alumina. The common method of preparing this liquid for the use of the dyer and calico-printer 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 sul- phate, and the acetic acid previously in combination with oxide of lead or lime combines with alumina to form a soluble acetate. To produce complete de- composition 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 1 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 ex- pressed in the following diagram : ALUMINOUS MORDANTS. 281 / 1 eq. sulphate of potash -j^ g I 24 eqs. water alum \ 1 eq . sulphate f o i i • ^ j. ^ c I , f ->3 eqs. sulphuric / tate oi I 01 alumina | ^ . , ^ / , ^ I acid / alumma. 3 eqs. r 9 eqs. water acetate -J 3 eqs. acetic acid of lead I 3 eqs. oxide of lead _ 3 eqs. sulphate 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 pur- poses 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 sul- phuric acid contained in the excess of alum. The following proportions of the materials afford a strong mordant of specific gravity about 20° T wad- dell* (1100), 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 sul- phate of lead to settle, after which the supernatant liquid may be decanted for use. * Degrees on Twaddell's hydrometer may be converted into the ordi- nary sp. gr. formula (water being 1000) by multiplying them by 5 and adding 1000. 282 DYEING AND CALICO-PRINTING. A red liquor, better adapted than the above for producing a yellow dye with the colouring 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 neu- tralizing with quick-lime the crude acetic acid or pyroligneous acid afforded by the distillation of wood; but the red liquor thus prepared does not pro- duce with colouring matters such delicate and bright shades as that prepared by acetate of lead. The usual proportions of acetate of lime and alum em- ployed 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 commerce, red liquor usually has a spec. grav. about 18° Twad. The following mode of preparing red liquor by acetate of lime is recommended by M. Kcechlin- Schouch (^Bulletin de la Societe industrielle de Mulhausen, 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 gra- vity 16° Twad. The resulting red liquor has the density, while hot, of 22° Twad., but on cooling it deposits crystals of alum, and falls in specific gra- vity to 18° Twad. ALUMINOUS MORDANTS, 283 In neither of the preceding preparations is suf- ficient acetate of lead or acetate of lime employed to decompose the whole of the sulphate of alumina in the alum, and it is doubtful, moreover, whether acetate of lime, in any quantity, would effect the complete decomposition of sulphate of alumina. But this undecomposed alum or sulphate of alumina, in- stead 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 alu- mina 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 alum. The temperature at which the precipitation commences varies according 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 281, the precipitation commences at about 154° Fahr. If the source of heat is with- drawn soon after the precipitate appears, so as to avoid the evaporation of acetic acid and the ag- gregation 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 subsulphate does not redissolve on cooling, nor even 284 DYEING AND CALICO-PRINTING. on the addition of free acetic acid. Such a precipi- tation of insoluble subsulphate, accompanied with the evaporation of acetic acid, always occurs during the drying and " ageing " of cottons printed with red li- quor.* A solution of pure acetate of alumina obtained by dissolving recently precipitated hydrate of alumina in acetic acid is uncrystallizable, and dries, on evaporation, into a gummy mass, very soluble in water. The aqueous solution 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 pro- duced 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 sulphate 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 colours containing a strong acid, such as muriatic, sulphuric, or nitric, in the free state. The strong acid combines with the * Concentrated red liquor deposits a small quantity of the subsul- phate of alumina at common temperatures, if kept for a considerable time. The precipitate thus gradually formed is sometimes too aggre- gated to be redissolved on the application of acetic acid. ALUMINOUS MORDANTS. 285 alumina of the acetate, and liberates acetic acid, which exerts no corrosive action on the fibre of the cloth. 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. Koechlin-Schouch. A solution of caustic potash 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 water. 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 alu- minate of potash is suspended 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 ventilated, 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 paying particular attention to the means of producing a proper ventilation in the " hanging" or " ageing" room, if the complete precipi- tation of the alumina during that stage of the process is required. 286 DYEING AND CALICO-PRINTING. The time of hanging the mordanted goods, how- ever, is seldom prolonged sufficiently to allow of the complete decomposition of the aluminate of potash. This is ensured by afterwards passing the cloth through a dilute solution of muriate of ammonia,* which immediately determines the complete precipita- tion 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 : Aluminate /Alumina .... free. of potash i Potash g^^^^" ^water. ^ v ( 1 otassium Muriate of j ^!\^-- j W'-"?^^ "'^^^ u . . • „^^„„- \ acid ( Chlorine -^chloride of potassium. V Ammonia .... tree. 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 effects obtained by alumi- nate of potash, and those by aluminate of soda. The other simple preparations of alumina which are occasionally used as mordants are, nitrate of alu- mina, chloride of aluminum, and tartrate of alumina. 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 mixing con- centrated solutions of equal weights of alum and nitrate of lead, when sulphate of lead is formed and * The muriate of ammonia is sometimes mixed with the dung-beck, and sometimes with the solution of" dung substitute." In a few particular styles of calico-printing, where the ageing of cottons printed with alumi- nate of potash is altogether omitted, the cloth is passed through a solu- tion of muriate of ammonia before the dung emulsion. TIN MORDANTS. 287 precipitated, and nitrate of alumina remains in so- lution. Tin mordants. — Several preparations of tin are employed as mordants in dyeing and calico-print- ing, comprising salts of tlie protoxide and of tlie 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 colouring matters, pro- ducing distinct and definite combinations ; and the compounds with the peroxide are generally distin- guished for possessing a vivacity of tint far superior to that presented by the combinations of the same colouring 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 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 am- monia; and 3°. A mixture of nitric acid, muriate of ammonia, and common salt. The perchloride of tin, or a mixture of the per- chloride and pernitrate, is also sometimes prepared from crystals of the protochloride (salts of tin) by 288 DYEING AND CALICO-PRINTING. means of nitric acid or aqua regia. The nitric acid used for this purpose should be quite free from sul- phuric 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 per- chloride and the protochloride. A common process for preparing a mixture of the two chlorides is to add granulated tin very gradually 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 insoluble peroxide, which is deposited as a white powder. The above proportions answer well for a mordant for general use, and especially for Brazil-wood; but for particular purposes the proportions of muriatic 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 protochloride made by dissolving tin in a mixture of nitric acid and sal-ammoniac, is much used by silk and woollen dyers, but a considerable difference exists between the proportions of the mate- rials as recommended by different dyers. For general purposes, the solution afforded by the following pro- portions receives a decided preference : TIN MORDANTS. 289 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 prevent 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 ob- tain crystals. It is chiefly used as a mordant with peachwood. Peroxide of tin is often applied to cloth in the state of the soluble combination 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 perchloride of tin, until the precipi- tate at first produced is entirely redissolved. If a piece of cotton impregnated with such a solution is dipped into dilute sulphuric acid, or a solution of muriate of ammonia, the alkaline combination on the cloth is decomposed, and peroxide of tin precipitated 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 muriate of am- monia (page 286). Protoxide of tin is frequently used as a mordant u 290 DYEING AND CALICO-PRINTING. alone, as well as the peroxide. This oxide may be applied from the protochloride of tin, which is pre- pared 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 of concentrated muriatic acid, and on evaporation the solution affords small colourless crystals, distin- guished as salts of tin. The solution of the pro- tochloride 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 protochloride. 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 adding the alkali to the solution of protochloride 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 protochlo- ride 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 am- monia which combines with the protochloride to form a double salt, less disposed to absorb oxygen than the pure protochloride. The colours of the compounds of colouring mat- ters 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. IRON MORDANTS. 291 On this account, a practice sometimes pursued in dyeing cotton goods by a tin mordant, is first to apply the tin in the state of protochloride, and to form the peroxide afterwards, within the fibre, by wincing the goods in a dilute solution of chloride of lime. Iron mordants. — The principal simple prepara- tions of iron which are employed as mordants are the following : copperas, which is the sulphate of the protoxide ; iron liquor, which is an impure ace- tate of the protoxide ; the pernitrate, the sub-persul- phate, 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 affinity of sulphuric acid for protoxide of iron is an impediment to the formation of an inso- luble subsalt. Acetate of iron; iron liquor. — The iron mor- dant commonly used in calico-printing 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 sul- phate of lime or sulphate of lead, which falls as a heavy precipitate, and acetate of protoxide of iron, which remains in solution. For the complete de- composition of copperas by acetate of lead, 10 parts of the former require about 1 3^ parts of the latter ; but in the preparation of acetate of iron in this way on the large scale, the copperas is always em- ployed in excess, being seldom in so small a pro- u 2 292 DYEING AND CALICO-PRINTING. portion 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 obtained by the distillation of wood. A dark brown solution, known as the pyrolignite of iron or iron liquor, is thus obtained, composed of the acetate of the protoxide of iron, and a quantity of tarry, oily, and spirituous matters produced in the destruc- tive distillation of wood. As a mordant, this mix- ture is in general preferred to the purer article pre- pared 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 unctu- ous 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 de- canted, so as to avoid the formation of the insoluble sub-pernitrate of iron. This solution of iron is used as a mordant with vegetable colouring matters, and also for producing a buflf colour with an alkali (see IRON MORDANTS. 293 page 256), and Prussian blue with yellow prussiate of potash. 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 ni- trate 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 perliitrate prepared as above. The peroxide of iron at first precipitated may be re- dissolved on agitation, if only a small proportion of alkali 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 (page 278), and the other to red liquor (page 280). The first is prepared by partially decomposing, 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 redis- solved by the undecomposed persulphate, giving rise to the subsulphate of the peroxide. The prepara- tion of peroxide of iron, analogous to red liquor, may be made by adding one part, by weight, of acetate of lead to four parts of a solution of per- sulphate of iron of the density 1-65. Sulphate of 294 DYEING AND CALICO-PRINTING. lead is precipitated, and the solution comes to con- tain subsulphate of the peroxide of iron, and per- acetate 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 mor- dants, which imparts considerable brilliancy to the tints of all compounds of colouring matters (par- ticularly that of madder) with peroxide of iron. This liquid, known as " assistant mordant," or " pa- tent purple liquor," is made by digesting farinaceous substances, starch, or sugar, in warm nitric acid, of moderate strength. The temperature of the mix- ture is not allowed to become high, in order to prevent the formation of oxalic acid. When all the nitric acid present is decomposed, a little py- roligneous 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 in- creased to five or six measures. 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 acidu- lous salts on the tints of some vegetable and animal colouring matters, when applied in a diluted state to the compounds of colouring matters and mordants, is ACTION OF ACIDS ON COLOURING MATTERS. 295 a subject which deserves 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 infusion of the colouring matter, are of frequent occurrence; and some bright shades of colour cannot 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 colour. 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 colour of the cloth changes from drab to slate colour 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 colour of the compounds of both oxides of tin (but espe- cially that of the protoxide) with the colouring mat- ter of logwood may also be greatly enlivened by the application of very dilute sulphuric acid, and a good scarlet or crimson cannot be obtained from cochineal with a tin or aluminous mordant without the in- troduction of tartaric or oxalic acid or cream of tartar. That the mode of action of the acid in such cases varies with different colouring matters and mordants hardly admits of doubt. The quantity of acid re- quired in some cases is far too small to warrant 296 DYEING AND CALICO-PRINTING. the supposition that it enters into a permanent che- mical union with the colouring matter and mordant ; but in other cases a sensible quantity of acid dis- appears, and seems to enter as an essential consti- tuent into the composition of the colouring material. In cases where the acid does not enter into a permanent chemical combination with the mordant and colouring matter, it may be considered to act in two ways : 1. By preventing the deposition of an excess of the colouring matter on the mordanted cloth, or by removing such an excess, if already deposited, through its solvent power ; 2. By effecting the disintegration of the particles of the mordant, whereby the latter is enabled to form a more intimate combination with the colour- ing material. When a piece of cotton cloth impregnated with a mordant in the ordinary manner is immersed in the dyeing decoction, it often absorbs more colour- ing matter than is necessary to form what may be considered as the neutral compound of colouring matter and mordant. But this excess of the colour- ing principle is frequently prejudicial to the tint of the compound of the mordant with a smaller pro- portion of colouring matter, with which the excess is in a state of loose combination, being held, pro- bably, by a mere attraction of surface (see page 237), and not by chemical affinity. Thus the compounds of both oxides of tin with an excess of the colouring mat- ter of logwood are considerably inferior in vivacity of colour to the compounds of the same oxides with ACTION OF ACIDS ON COLOURING MATTERS. 297 a smaller proportion of the colouring matter. The dullness of the colour of a piece of cotton mordanted with iron liquor, dunged, winced in hot chalky water, and dyed in a decoction of valonia (see page 295), 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 coloured t an- nate 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 excess of colouring matter to the mordanted cloth; an acidulous liquid being generally a more power- ful solvent of the colouring principle than pure water ; and: a corresponding effect may take place when the dyed cloth containing an excess of co- louring 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 par- ticles of the mordant become placed in a better con- dition for combining with and retaining the colour- ing 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 colour- ing matter is absorbed when the cloth is immersed into the dyeing liquid containing no free acid. A remarkable difference may be observed between the quantity of the colouring matter of logwood -ab- 298 DYEING AND CALICO-PRINTING. sorbed 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 co- louring matter absorbed by a piece of cloth containing the same mordant, 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 pro- duced, 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, causes the production of an uniform and bright colour 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 cannot be supposed to act in all cases by forming a permanent chemical combination with the colouring material. 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, par- ticles of the mordant thereby become exposed, and placed in a condition to unite intimately with the colouring material, the latter being derived either from the dyeing liquor or from the excess in loose combination with the exterior particles of the mor- dant. The disintegration of the mordant by the ACTION OF ACIDS ON COLOURING MATTERS. 299 acid may possibly be a mere mechanical effect,* in- dependent of any chemical alteration of the mor- dant, but the action of the acid admits of a more satisfactory explanation. The precipitated mordant is probably first dissolved by the acid, but is im- mediately reprecipitated in intimate combination with the colouring matter ; the acid thereupon becomes 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 270) to the dyed cloth con- taining an excess of colouring matter, its action is of the same nature. An illustration of this prin- ciple 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 mordant, dyed to a drab colour in in- fusion of valonia (see page 295). The tannin or the astringent principle of the valonia is united only with the exterior particles of the oxide of iron, but is there contained in excess; on the application of the acid both the excess of tannin and the in- terior particles are dissolved, brought into contact, and precipitated in intimate combination, the mu- riatic acid being liberated to act on other portions of oxide of iron and tannin in a similar manner. The preceding explanation of the enlivening ef- * Examples of the disintegration of precipitates, by being digested in an acid liquid, which exerts no chemical action on the precipi- tates, are by no means rare. Thus, an intimate mixture of pure Prus- sian blue with hydrochloric acid appears to become a perfect solution on standing ; but the particles of the pigment are merely disintegrated, and still exist in an insoluble form. 300 DYEING AND CALICO-PRINTING. fects produced by the application of acids to com- pounds of organic colouring 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 per- manent chemical combination with the colouring ma- terial. In other cases a sensible quantity of free acid unites with the compound of mordant and co- louring matter, and modifies the properties of the latter by causing a new disposition of its particles. That the purple compound of the colouring matter 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 pro- tochloride of tin is added to a decoction of cochineal, a purple lake is precipitated, consisting of a compound of the colouring matter of cochineal with protoxide of tin mixed with an excess of the protoxide. This lake is collected on a filter, carefully washed with dis- tilled water, and digested in a given quantity of a solution of carbonate of soda of known strength. The proper compound of colouring matter and oxide of tin then dissolves in the alkaline carbonate, and the excess of oxide of tin remains undissolved. On mixing an excess of sulphuric acid with the alkaline solution the pure lake is reprecipitated of a much richer colour than before being thus treated ; but the reprecipitation of the pure lake requires con- siderably 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 ne- cessary for the neutralization ; but on adding more, ACTION OF ACIDS ON COLOURING MATTERS. 301 the precipitation immediately commences, though no free 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 colouring matters, or com- pounds of colouring matters and mordants, experience by combining with an acid in such a case as the preceding; some considerations on this subject, how- ever, may not be without a practical application in the operations of the dye-house. Soluble vegetable and animal colouring matters have the property of uniting both with acids and bases : with acids they form feeble combinations pos- sessed of lively tints ; but with bases they affiDrd stronger combinations, having less vivacity of colour. In general, the more closely a mordant resembles an acid in its chemical character, the brighter are the tints of its compounds with colouring materials. Thus, peroxide of iron and peroxide of tin, which appear to act the part, sometimes, of feeble acids, produce compounds with colouring matters having brighter colours than similar compounds with prot- oxide 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 colouring materials, than the peroxides, especially if the prot- oxide is of itself a stable substance, as protoxide of tin. Some metallic protoxides also unite with a larger quantity of colouring matter than peroxides, but it is uncertain whether the excess is held by chemical affinity or by a mere attraction of aggrega- 302 DYEING AND CALICO-PRINTING. tion dependent on the state of the surface of what we may consider as the neutral compound of colour- ing 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 pro- toxide of tin as the mordant. But as very few strong acids can be applied to cot- ton goods without weakening the fibre to a greater or less extent, it becomes necessary, in order to obtain bright colours, to apply such mordants only as possess some resemblance to acids, as alumina, and the per- oxides of iron and tin. In the action of such bodies on soluble organic colouring materials two forces may be recognized : by one, the mordant acts as an acid, producing an enlivening of tint ; by the other, it acts as a base, producing an intimate and stable combi- nation. * If silk and wool are digested in dilute sulphuric or muriatic acid, a portion of the acid combines with the stuffs, and the liquid is found weaker after than before the immersion. The animal tissues also com- bine with tartaric acid when digested in a solution 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 di- gested in dilute sulphuric or muriatic acid, abstracts the water in pre- ference to the acid, thus making the liquid more acid than before the immersion of the cotton. DUNGING. 303 DUNGING. As the precipitation of the mordant in the form of an insoluble subsalt during the hanging or " age- ing" of cotton goods is never complete, it becomes necessary to remove the unprecipitated mordant from the cloth before the dyeing, else a quantity of su- perfluous colouring matter will be deposited on the surface of the cloth, which would have to be removed by subsequent operations, besides causing an unne- cessary impoverishment of the dyeing liquid. But the necessity for removing 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 por- tion of it may become distributed over the whole surface 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 mordant consists in simply drawing the dried goods through a warm emulsion of cow-dung and water. The emulsion is usually contained in two stone cisterns, 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 con- tains only half this proportion of dung. The cloth, on being taken from the " ageing" room, is first drawn pretty quickly through the emulsion contain- ing most dung, and immediately afterwards through the other; the cisterns being usually placed end to 304 DYEING AND CALICO-PRINTING. end, to allow the cloth to be conducted 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 this 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 314), 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 precipitation of alumina, which it ef- fects by a reaction explained at page 286. 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 aluminous, iron, and tin mordants, when applied to the cloth before the colouring matter. The time of immersion, the temperature of the mix- ture, 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 thickening paste 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. 305 Dunging is one of the most important steps in tlie 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 determination 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 uncer- tainty. 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 X 306 DYEING AND CALICO-PRINTING. 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 albuminous 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 per- manently to the cloth. But it appears that a small portion of the superfluous mordant dissolved from the cloth by the hot water, instead of being afterwards 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 combina- tion is, that it is incapable of affording a precipitate 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 analogous to that of several soluble combinations of metallic oxides with organic matters which are not affected by cer- tain chemical reagents in the same manner as ordinary salts of such oxides. Thus, a salt of the protoxide of copper in the presence of several organic sub- stances, sugar for instance, is not precipitated by a solution of a caustic alkali ; the double tartrate of the peroxide of iron and potash does not afford a pre- cipitate of peroxide of iron when mixed with a solu- tion 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- DUNG SUBSTITUTE. 307 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 combination more insoluble than the previous sub- salt. 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 albuminous matter of the dung seems also to exercise an influence as a detergent 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 this country, 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 patent * On the Continent, it is a common practice to add to the dung emul- sion, 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 cloth contains a free acid or acidulous salt, as lemon-juice or bisulphate of potash. The smallest ex- cess of an alkaline carbonate should be avoided when alumina is the mordant on the clotli. X 2 308 DYEING AND CALICO-PRINTING. has been obtained by Mr. Mercer, Mr. Prince of Lowell, Massacliusets, 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 phos- phate of lime; the acid not being applied in suffi- cient quantity to decompose the phosphate of lime entirely, but to produce 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 evapo- rated until the residuary mass becomes almost dry. When the concrete thus obtained is mixed with water, it affiDrds a solution of phosphate 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 efficient sub- stitute for all the essential, or at least, for all the im- portant, constituents of the dung emulsion. To sup- ply 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 gelatine until it attains a density about 36° Twad- dell (1-180). The advantage of making this addi- DUNG SUBSTITUTE. 309 tion to the phosphates was first pointed out by Mr. Mercer. When the " aged" cloth is passed through a mixed solution of substitute and gelatine, the latter greatly facilitates the separation of the loosely combined mor- dant, and prevents its reattachment, while the phos- phate of lime and phosphate of soda in the former serve to fix the alumina and oxide of iron in more intimate combination with the stufis by converting them into phosphates. The acids previously in com- bination 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 substitute 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 consecutively ; that first applied, which is considerably stronger than the other, may be con- tained 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 immersion 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 gallon. Six gallons of this substitute liquor and two gallons 310 DYEING AND CxiLICO-PRINTING. 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 he the same, in general, as that of the dung-beck, in the 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 re- newed by the addition of fresh quantities both of substitute liquor and cleansing liquor. A gallon 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 solution 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 substi- tute 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. * If the work is heavy, it is also recommended to pass them between the squeezing rollers and again wash tlieni in water. DUNGING. 311 The only remaining operation to wliicli 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, the pieces are sometimes first passed through the common dung emulsion and afterwards 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 afterwards winced in a solu- tion 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 exposure to dung or substitute of cloths mor- danted with alumina, should not be prolonged a suf- ficient time to allow of the union of the alumina with a full proportion of phosphoric acid ; for colouring matters do not readily displace phosphoric acid from such a combination. The phosphate of iron, on the contrary, is easily decomposed by colouring matters. In a few dyeing processes where it is of importance to avoid the aggregation of the particles of the mor- dant 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 312 DYEING AND CALICO-PRINTING. case, the chalk serves to fix the mordant on the cloth by withdrawing the small quantity of acid remaining in the subsalt; 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 mordant, the process of wincing in chalky water should not be prolonged, and only a small proportion of chalk should be employed, as the precipitated 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 hranning, which consists in wincing the goods in a mixture of bran and hot water. The action of bran is probably quite analogous to that of dung, the unprecipitated mordant dissolved by the water being separated from the liquid by the insoluble ligneous matter, while the undissolved mor- dant becomes more strongly attached to the cloth by combining with the mucilaginous and glutinous matters 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 afterwards dyed to deli- cate shades of colour by means of cochineal and fugi- tive colouring matters. After having been thus exposed to the action of either dung, substitute, chalk, or bran, the mor- danted goods are ready to be exposed to the infusion of the dye-stulf; and in general, the sooner this is done, the better is the colour they assume. The different vegetable colouring matters vary so DYE-BECK. 313 considerably in properties, that few observations of general application can be offered on the modes of preparing the various dyeing liquids. If the sub- stance is very soluble, its solution may be made in the cold; but if only slightly soluble, heat may be applied, provided the colour is not deteriorated by exposure to a moderate heat. When a highly charged solution is required, (such as the topical and steam co- lours used in calico-printing,) concentration by eva- poration is had recourse to ; many vegetable colours, however, will not support a continued ebullition with- out losing something of their colour. If the goods are not kept in constant motion when in the dye- beck, the infusion should be freed from the insoluble ligneous 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 colour 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 vegetable 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 increased by the introduction of steam. In the dyeing of cottons, motion may be commu- nicated to the goods, while in the dye- beck, by a Avince or reel placed horizontally over the middle of the dyeing vessel, so that the cloth may be made to descend into either compartment of the dye-beck by 314 DYEING AND CALICO-PRINTING. tlie rotation of the reel. The dyeing vessel, wliich is commonly constructed of wood,* is represented in cross and longitudinal section at figs. 31 and 32 : Fig. 31. Fig. 32. * — ^ ^ a a is the reel, containing six long wooden spars on its circumference ; it is set in motion by being con- nected with one of the driving shafts of the factory. Steam is admitted to the vessel by the pipe 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 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 in motion by the same reel, they being prevented from en- tangling by wooden bars represented at which * For madder work, dye-becks made of iron have been lately sub- stituted for those of wood. When the metal is completely covered with oxide, it exerts no injurious action on the colouring matter. DYE-BECK. 315 reach from a cross-bar at the top of the vessel to the back. An inclined partition, f, extends through the whole length of the dyeing vessel, formed of several wooden spars placed a few inches apart from each other. The ordinary dimensions of the dyeing vessel are, six feet in length, four 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 colouring mat- ters which are naturally soluble in water, by the intervention of a mordant. If the colouring prin- ciple is insoluble in water, the mordant may be dis- pensed with; but it then becomes necessary to de- vise some means of obtaining such a solution of the colouring substance as will allow the deposition of the latter in its insoluble state, when a cloth im- pregnated with the solution is exposed to some che- mical agent. This forms the third style of dyeing in the classification proposed at page 262. The prin- cipal insoluble vegetable colouring materials are in- digo, safilower, and annatto, the nature of the pro- cesses for applying which to cloth has already been explained (page 243). The only other style of dyeing which remains to be noticed is entirely different 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 colour is imparted to silk and wool, not from the solution of a colouring matter, but by efiecting a 316 DYEING AND CALICO-PRINTING. certain chemical change in the fibre, through the action of dilute nitric acid. The orange colour 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-beck at the time of dyeing depends almost entirely on the nature of the colouring matter. If it is readily attachable to the tissue, as indigo and colouring 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 af- fords the most uniform colour, partly on account of the more ready disengagement of air-bubbles from between the fibres of the cloth. Dyeing with ve- getable and animal colouring matters 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 colouring principle. In a few dyeing processes, however, where the mor- dant 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 co- louring matter from some solutions at the ordinary temperature than at the boiling point. Where the operations are conducted on anything approaching a considerable 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 introducing it directly into the liquid by a pipe DYEING PROCESSES. 317 leading from the boiler; 2°, by causing it to cir- culate througli 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 consider- able influence on the tints of the decoctions prepared in them, owing to the solution of some oxide of cop- per from the surface of the metal, by an acid exist- ing either in the mordant or the dye-stuff". A so- lution 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-grey tint when kept for some hours in a boiling solution of alum with cream of tartar con- tained in a copper vessel, which would not happen with the same solution in a vessel of tin. In general, the vegetable and animal fibres be- come coloured much more readily when unspun than when wove into cloth. Wool in flocks, after having been washed, digested in an alkaline ley, and bleached by sulphurous acid, takes more colour than when spun into yarn, and the yarn more than when wove into cloth. This doubtless arises from the compara- tive difficulty with which the solution of the colour- ing matter obtains access to the internal fibres of the spun or woven tissue. The colour of the interior of a piece of thick woollen cloth dyed in the piece, is often less intense to the eye than the colour of the exterior. Certain disadvantages, however, some- 318 DYEING AND CALICO-PRINTING. times attend the dyeing of wool in flocks and in thread : some colours, for instance, are susceptible of alteration in the subsequent manipulations in weaving; the texture of the fibre is sometimes al- tered so as to present inconveniences in these ope- rations, 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, ac- cording to the style of work and the nature of the stulf operated on. When the goods have re- mained a sufficient length of time in the dye-beck, they are removed and carefully washed in water to separate the coloured liquid retained mechanically between the fibres. The drying of the washed goods, if of silk and wool, is usually effected by exposure to the air at common temperatures; but occasionally heat is applied, the goods being introduced into a well ventilated apartment heated by the circulation of steam-pipes. The drying of goods dyed with de- licate colours should always be performed in the shade. The following account of the course of finishing operations practised on calico printed and dyed ac- cording 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 in- tervention of a mordant. Some of the operations 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 FINISHING OPERATIONS. 319 surmounted by a reel, similar to that shewn in figs. 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 par- ticular construction, called the dash-wheel (fig. 33). Fig. 33. This is a hollow, circular, 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 the compartments through the circular openings in front, and water being admitted, the wheel is made to ro- tate rapidly, and thus wash the cloth with consider- able agitation. In the washing of cloths which require delicate treatment, as those dyed with fancy or spirit colours, for which the action of the dash-wheel is much too 320 DYEING AND CALICO-PRINTING. energetic, another washing apparatus is employed, called the rinsing machine^ an idea of the ordi- nary construction of which will be afforded by the representation 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 transversely into from six to Fio-. 34. 3j \ -I ten compartments, by partitions which gradually de- crease in height from the higher to the lower end of the vessel. In each compartment except the highest, are placed three rollers, to regulate the passage of the cloth through the cistern, two of the rollers being near the bottom and the other at the top. Above each par- tition are placed two more rollers nearly in contact ; and those above the higher end of the cistern and the first partition are squeezing rollers subject to consi- derable 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 compart- ment successively, being drawn through by the trac- tion of the squeezing rollers at the upper end. A FINISHING OPERATIONS. 321 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 con- tact with purer portions of water and is discharged at the top perfectly clean. In the machine repre- sented in the above figure, the water flows from one compartment into another through apertures near the tops of the partitions, and not over the par- titions. In another form of the rinsing machine, the water passes from one compartment into the next through apertures at the tops and bottoms of the partitions alternately. It is to be observed that this machine is used only for goods which require more delicate treatment than is compatible with the dash-wheel or the wince-pit. While, the cloth is in the dye-beck, a considerable quantity of colouring matter attaches itself to the sur- face of the cloth, not in chemical combination with the mordant, but too strongly attached to be easily re- moved by washing in clean water. To get rid of this superfluous colour, the cloth, after having been washed at the dash-wheel, is winced either in a mix- ture of bran* and boiling water, containing about * In effecting the removal of this excess of colouring matter, the most active constituent of the bran seems to be the husky part. The feebly combined colouring principle dissolved by the hot water and the muci- laginous matters present, instead of being retained in solution, is preci- pitated on the husky surface, and thus prevented from again attaching itself to the cloth. Coarse bran is better adapted for this purpose than fine, and flour seems to be altogether useless. An interesting memoir by M. Koechlin-Schouch, on the use of bran in this operation (termed "clearing"), is contained in the ninth volume of the Bulletin de la So- ciete Industrielle de Mulhausen. Y 322 DYEING AND CALICO-PRINTING. a bustel 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 tints of all vegetable colouring principles are slightly deteriorated by these agents. For most vege- table colouring matters besides madder, bran only is admissible ; and even in bran-water, the wincing sometimes must not exceed a few minutes. With madder colours only, the wincing may be continued for from ten to twenty minutes. The complete removal of the superfluous colour from a piece of cloth which is to present a white pattern is generally effected, when madder is the only vegetable colouring matter present, by wincing the cloth for a few 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 branning is altogether omitted when the solution of chloride of lime is employed. Few vegetable colouring 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, sometimes by exposure to air and light, but the process of branning or soap- ing is generally found to be sufficient of itself. After having been thus cleared of the redundant colour, 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 FINISHING OPERATIONS. 323 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 purpose is represented in perpendicular section across the centre at fig. 35, and as viewed from above in fig. 36 : a and h are two copper cylinders connected together at bottom so as to form one vessel, which rotates with the axis c. These cylinders are en- closed in a wooden case which is in communication, Fig. 35. Fig. 36. e at bottom, with a drain or gutter. The cylinder h has a great number of small perforations, and is di- vided by partitions into four equal compartments. The wet cloth which is to be dried is placed in the compartments between the two cylinders, 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 perfora- tions in the cylinder h to the outer case, from whence it flows out by a gutter or drain. After a few minutes the cloth becomes nearly dry, and when the Y 2 324 DYEING AND CALICO-PRINTING. macliine is opened, is found to be strongly com- pressed against tlie 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 319). When the cloth has been thus far dried, either by the squeezers or the "water extracter" just described, it is folded evenly and then passed, in a length of ten pieces, through a mixture of blue starch and water. Fig. 37. A cross section of the starch- ing machine is represented in fig. 37: a is a wooden trough to contain the muci- laginous liquid ; 5 is a small cylinder revolving in the li- quid; around this is passed the web of calico c, which is then drawn over a fixed brass bar with diagonal notches on its front, for the purpose of removing creases from the cloth ; e is a wooden cylinder covered with cloth, revolving in close con- tact with the brass cylinder the calico is passed between these cylinders to be freed from the super- fluous starch, and is then rolled olF upon the cylinder the axis of which is not fixed, but so contrived 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 * This machine is known by the name of " water extracter." CALENDERING. 325 passed through the steam drying machine^ which consists of several hollow copper cylinders, each about twenty inches in diameter and three feet in length, fitted up with machinery by which all the cylinders or drums may be rotated together at the same velocity. Steam is admitted to the drums through stufiing boxes at one end of the axes, and at the other end are placed pipes to discharge the condensed water. The number of drums arranged together in one system varies from five to thirteen, according to the quantity of work required; they are sometimes placed in one line, but usually in two lines, one im- mediately over the other (as fig. 38), with the cir- Fig. 38. cumference of one drum distant about four or six inches from that of the next in the line of the axes of the drums. The calico passes through the ma- chine in the direction of the arrows in the above figure. The drums are surmounted by a hood and flue for the purpose of conducting the steam out of the chamber. The last finishing operation to which dyed and printed cottons are sometimes subjected is calender- ing or glazing, the object of which is to make the surface of the cloth smooth, compact, and uniform. This is efiected by passing the piece between two 326 DYEING AND CALICO-PRINTING. cylinders 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 neces- sary. The material of the other cylinder was for- merly wood, but for some years 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 cy- linder. The paper cylinder is 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 diameter than the remainder of the cylinder. The discs being screwed down tight, the cylinder is placed in a stove, and kept for se- veral days at as high a temperature as the paper will bear without being charred or rendered very brittle. As the moisture is driven off, the pasteboard shrinks, and the screws must be tightened to keep the mass as compressed as possible. When no further dimi- nution in bulk is perceived, the cylinder is removed from the stove, and carefully 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 glazing of calicos was formerly executed by the hand with a hot iron, at an expense of about one ON THE WATER USED IN DYEING. 327 shilling per piece of twenty-eight yards ; the cost of glazing by machinery as above is from threepence to sixpence per piece. The purity of the water employed in dyeing ope- rations is a subject which deserves the especial at- tention of the practical dyer. The finest colours are in almost all cases obtained by making use of dis- tilled water, that being free from all earthy impuri- ties. 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 falls down in combination with the colouring matter as an inso- luble precipitate, occasioning 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 colour, and imparts only a faint red colour 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 colour. In the first case, the quantity of madder red remaining in the residue is much less than in the second. The madder red at first dissolved is precipitated by the lime of the spring water, im- parting to the residue its dark colour, and is dis- 328 DmNG AND CALICO-PRINTING. solved 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 into sulphate of lime, which scarcely alfects the brilliancy of the colours of the dyed or printed goods. It is of importance that there should be no excess of the acid. When cochi- neal colours are washed, distilled water is usually employed ; but where this cannot 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 car- bonate 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 con- tains in solution a quantity of decomposed vegetable matter, which is also very detrimental to certain colours. Not only is the shade of colour modified by the attachment of the organic matter, but certain metallic colouring 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 ge- neration of soluble earthy or alkaline sulphurets through the decomposition of the soluble sulphates ON THE WATER USED IN DYEING. 329 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 thus produced. 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 coiTsumed 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 colouring 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 Lon- don, the only water employed is that raised from an Artesian well. In one dyeing process, however, namely, the pro- duction of a black colour 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 liquid a given depth of colour, distilled water requires more dye-stulf 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 cop- peras. A faint purplish colour will be developed 330 DYEING AND CALICO-PRINTING. in both jars ; but if one is filled with Spring water, the colour in that rapidly becomes dark reddish- black, and one-half more water is required to reduce it to the same shade of colour as the other. The water which is found by experience to be best adapted for dyeing with galls and sulphate of iron dilfers from distilled water in containing sulphate of lime, carbonate of lime held in solution by free carbonic acid, and chloride of calcium. The bene- ficial 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 experiments, the purple colour is struck as rapidly and as deeply as in the spring water ; chloride of calcium and sulphate of lime, on the contrary, pro- duce no sensible change either in the depth of colour or the tint. 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 colour, converting it into a reddish-brown. Ammonia, lime-water, and the alkaline bicarbonates also produce a reddening, and if applied in consider- able quantity, a brownish tinge. But the dyeing operations in which hard water CALICO-PRINTING PROCESSES. 331 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 pro- duced, yet each colour 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 compli- cated. These styles are quite distinct from one an- other ; each requires a peculiar process and a different manipulation. The six styles alluded to are the following : 1. Madder style^ for soluble vegetable and ani- mal colouring 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 colour is imparted by passing the cloth through the dye-beck. On those portions of the cloth on which the mordant is applied, the colouring matter attaches itself in a durable manner, but on the unmordanted portions the colour is feebly attached, so that it may be wholly removed by wash- ing 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 colours. 332 DYEING AND CALICO-PRINTING. — Such colouring matters as are incompletely, or not at all, precipitated from their solutions on being mixed with certain solutions of a mordant, are some- times printed on the cloth with the mordant, and the fixation of the colour is afterwards effected by ex- posing the cloth to steam. Some colouring 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 colours {padding style). — To produce a figure in a mineral colouring material the cloth may be first printed with one of the two saline solutions, and be afterwards uniformly im- pregnated with the other. To obtain a ground of a mineral coloui', 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 the property of preventing those portions of the cloth on which it is applied from acquiring colour when afterwards exposed to a dyeing liquid. Eesists are divisible into two classes ; one is employed to prevent the attachment of a mordant, and the other that of a colouring matter. 5. Discharge style. — The object of the processes belonging to this style of work is the production of a white or coloured figure on a coloured ground. This is effected by applying topically to the cloth already dyed or mordanted, a substance called the discJ larger, which has the property of decomposing or dissolving out either the colouring matter or the CALICO-PRINTING PROCESSES. 333 mordant. Chlorine and chromic acid are the com- mon discharging agents for decomposing a vegetable or animal colouring matter, and an acid solution for dissolving a mordant. 6. For China blue. — This is a very peculiar style, and is practised with one colouring 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 suc- cessive application of lime and copperas, with expo- sure to the air. The topical application of the colouring 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 re- quired, the figure is sometimes formed by the inser- tion 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 colour or mordant by pressing it gently on a piece of superfine woollen cloth, called the sieve, which is kept uniformly covered with the thickened colouring matter or mordant by an attendant boy or girl, called the " tearer," (corrupted from the French word tireu?',) who takes the colour up by a brush from a small pot and applies it evenly to the woollen cloth. This cloth is stretched 334 DYEING AND CALICO-PRINTING. tight over a wooden drum, which floats in a tub full of old paste or thick mucilage to give it suf- ficient elasticity to allow every part of the raised device on the block to acquire a coating of colour. The calico being laid flat on a table covered with a blanket, the charged block is applied to its sur- face (the printer being guided where to apply the block by small pins at the corners) 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 colour; hence, if the design contain five or more colours, 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 de- pressed parts in all the others. If the design, however, requires different colours to be applied in figures in straight and parallel stripes, all the stripes may be applied by one block at a single impression, and the block is also charged with the different colours by a single application to the surface of woollen cloth. The colours to be ap- plied are contained in as many small tin troughs as there are colours, arranged in a line. A little of each colour 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 colour 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 colours are blended into one another at their edges by a brush or rubber drawn to and fro in a straight line. CALICO-PRINTING PROCESSES. 335 An important improvement in the construction of the hand-block has been recently adopted in most well conducted print-works, which consists in the application of a stereotype plate as the printing sur- face. To make the stereotype 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 pro- duced 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 sufiicient number of the pieces is pre- pared, their surfaces 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 ma- chine called the Perrotine, in honour 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 three 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 coloured paste and then pressed successively against the cloth to be printed. The cloth is drawn by a winding 336 DYEING AND CALICO-PRINTING. 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 cen- tury 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- Fig. 39. sents the engraved cylinder or roller, mounted on a strong frame-work, so as to revolve against two other cylinders h and c. The cylinder c, which is covered with a woollen cloth, dips into the trough con- CALICO-PRINTING PROCESSES. 337 taining the solution of the colouring matter or mor- dant properly thickened, and thus acquiring itself a coating of the colour imparts some of it in the act of rotation to the engraved roller a: i is a large iron drum or cylinder, the surface of which is rendered elastic by several folds of woollen cloth ; around this drum travels an endless web of blanket-stuff, 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 colouring matter or mordant which is communicated to the engraved roller by the cy- linder 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 colour 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 roller ac- quires from the calico. With some colour mixture^ and mordants, those containing 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 colour mix- ture. Such is the method of printing calicos by the roller for a single colour; but the mordants or mix- tures for two, three, or even eight colours may be applied at the same time by having as many en- z 338 DYEING AND CALICO-PRINTING. graved rollers with their appendages revolving simul- taneously against the iron drum, as represented in fig. 39, by the dotted cylinders and troughs A, /i, i. Extreme nicety of arrangement is required to bring all the rollers to print the cloth at the pro- per places, but when once properly adjusted each may be made to deposit its colour 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 hammered 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 ordi- nary 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 m^Y/, of similar size, which is engraved by the common graver while in the soft state, and afterwards 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. CALICO -PRIIfTING PROCESSES . 339 Por some peculiar styles of pattern, the copper roller is etched instead of being engraved by indenta- tion. 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 pat- tern 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 having been etched on its whole surface, the roller is sus- pended for about five minutes 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 unacted on. The impor- tance and value of this method arises from its afford- ing 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 exten- sively practised of late in one of the best conducted print-works in Lancashire. It is only applicable to rollers to be used for printing a full ground, sprigs or other designs being left blank, for grounding in other colours if required by the block, at a subsequent ope- ration. The copper roller is, in the first place, painted with a resist varnish on its whole surface, with the excep- tion 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 after- wards, into clean water. From the water, the roller is transferred to a solution of sulphate of copper and z 2 340 DYEING AND CALICO-PRINTINa placed in connection with a galvanic battery, where- by it acquires a coating of copper on the designs where the varnish had not been applied. These raised designs are afterwards polished smooth, so that when the roller is in use, they become per- fectly 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, distinguished as " press printing," by which block printing with several different colours may be executed at one impression. A sketch of the principal parts of the press-printing machine is shewn in fig. 40. The block itself a consists of a well pre- pared 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 colours 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 printed; each one prints a different colour, 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 335). The mode of applying the colours to the printing surface is very ingenious. At the bottom of the CALICO-PRINTING PROCESSES. 341 wooden frame 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 Fig, 40. arranged in a line five little troughs (or as many as there are colours to be printed), containing the thickened colours. By means of a long 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 colours to the surface of felt, over which the colours are evenly spread by a brush in five Stripes without any intermixture. The breadth of 342 DYEING AND CALICO-PRINTING. the stripes is the same as the breadth of the stereo- type 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 colour. This being done, the block is raised, the colour-frame withdrawn, and the block caused to descend on the cloth, which it imprints in five rows with different colours. When the block is raised, the cloth is drawn lengthways over the table about six inches, or exactly the width of one stripe on the block: the "tearer" again slides over the cushion with more colour, 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 suc- cessively 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 colours and distortion of the pattern. 5. The only mode of printing which remains to be noticed is " surface printing," which is merely a mo- dification of roller printing, the cylinder being made CALICO-PRINTING PROCESSES. 343 of wood instead of copper. Tlie pattern is either cut in relief, as in the ordinary block, or it is formed by the insertion, edgeways, of flattened pieces of copper wire. This cylinder is mounted in a frame as the copper roller, and is supplied with colour by revolving against the surface of an endless web of woollen cloth, which passes into a trough containing the colour 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 practised more extensively in Ireland than in Lan- cashire. Thickeners. — The thickening of the solution of the mordant or the colouring matter in order to prevent the liquid from extending beyond the pro- per limits of the design, is a subject which requires considerable attention in the successful 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 colouring matters and particular mordants often re- quire particular thickeners. , Two similar solutions of the same mordant, equally thickened, but with different materials, afford different shades of colour when dyed in the same infusion ;* and the time re- quired for the fixation of the mordant duiing the * Solutions of salts of iron or copper thickened with starch give a deeper colour to the cloth, when afterwards dyed, than the same solu- tions if thickened with gum arabic. 344 DYEING AND CALICO-PRINTING. 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 commonly employed : 1. Wheat starch. 2. Flour. 3. Gum arable. 4. British gum. 5. Calcined potatoe starch. 6. Gum Senegal. 7. Gum tragacanth. 8. Salep. 9. Pipe-clay, mixed with either gum arable or gum Senegal. 10. China clay, mixed with gum arable or Senegal. 11. Dextrin. 12. Potatoe starch. 13. Eice starch. 14. Sago, common and torrefied. 15. Sulphate of lead, mixed with gum arable or Senegal. The most useful thickeners are wheat starch and flour. When either of these or any kind of starch (not roasted) is employed, the mixture with the mordant or colouring 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 unroasted starch is well adapted for thickening solutions containing a free acid or an acidulous salt; if other circum- stances, however, should render the introduction of CALICO-PRINTING PROCESSES. 345 another thickener inadmissible in such a case, the acid or acid salt is always mixed with the thicken- ing 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 con- sistency. Starch is almost the only thickener employed for mordants containing no free acid, and the mordant seems to combyie with the stuff more readily when thickened with starch than when thickened with gum. During the ebullition of starch with red liquor, a precipitate of subsulphate of alumina is produced (see page 283); but this precipitate is completely redissolved as the mixture cools, its solution being apparently facilitated by the starch. 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, cannot be well employed, as such solutions cause the formation of precipi- tates with an aqueous solution of gum. This objec- tion 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 colouring 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 sub- 346 DYEING AND CALICO-PRINTING. stitute"), are intermediate, both in their properties and applications, between common starch and gum arabic. Calcined potatoe starch is chiefly used with solutions applied by the padding machine, which require very little thickening. Gum tragacanth and salep are commonly employed as thickeners for solutions 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 colours. It gives considerable consistence to water, but the mix- ture is apt to become thin on standing. It is remarkable that a mixture of solutions of gum tra- gacanth and gum Senegal/^ both of tlie same strength, possesses only one-half or one- third the consistency of the two solutions before being mixed. Pipe-clay, China clay, or sulphate of lead, when mixed with either gum arabic 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 colouring matter, when the latter is applied to the whole surface of the cloth. When the mordant to be printed is colourless, 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 addi- tion of colour is called sightening. We proceed, in the next place, to consider some particular examples of printing processes in illustra- CALICO-PRINTING PROCESSES. 347 tion of the six diifferent styles of work noticed at page 331. I. MADDER STYLE. The madder style is applicable, not only to the dye-stuff from which it derives its name, hut to nearly all organic colouring materials which are so- luble in water, and capable of forming insoluble com- pounds with mordants, and is much more extensively practised than any other style. The ordinary course of operations to which a piece of cotton is subjected in order to be printed and dyed according to ■ this style is the following: 1. Printing on the itkickened mordant, which is commonly done by the cylinder: machine. 2. Immediately after the imprinting of the mor- dant, the cloth is dried by being drawn either through the hot-flue,* or over a series of thin sheet-iron boxes, heated by means of steam, and is then conducted into the "ageing" room, where it is suspended, free from folds, for one or two days, according to the nature of the mordant and the temperature. The ageing room should not be very dry, or heated above the ordinary temperature, except during winter. During this suspension, the greater part of the mordant undergoes a chemical alteration, by which it becomes attached to the cloth in an insoluble state. * The liot-fluc is a long gallery or passage, commonly heated by the flue of a furnace at one end, which runs through the whole length of the gallery on its floor. It is advantageous to have the upper surface of the flue formed of rough cast-iron plates, which become quickly heated and present a good radiating surface. A piece of calico (28 yards) is usually drawn through the flue in about two minutes. 348 DYEING AND CALICO-PRINTING. lied liquor and acetate of iron part with a portion of their acetic acid; the former affords a deposit of subsulphate of alumina, the latter of subacetate of iron, as before explained ; and the aluminate of potash affords a precipitate of alumina, through the action of the carbonic acid in the atmosphere (see page 285). Annexed is a specimen of calico in this No. 1. stage of the process, the mordant on which is red liquor, " sightened" with a little decoction of peach- wood or similar dye-stuff. 3. After having been suspended in the ageing room for a sufficient time, the printed cloth is drawn through the dung-becks, or else through a strong solution of dung substitute (page 307), whereby a part of the undecomposed mordant is separated from the cloth and prevented from acting on those parts which had not been printed, the thickening paste is removed, and the mordant remaining on the cloth becomes more strongly attached, by uniting with some of the constituents of the dung or of the. sub- stitute. CALICO-PRINTING PROCESSES. 349 When taken out of the dung-becks, the cloth is immediately washed in a cistern of cold water, or sometimes both squeezed and washed, and then com- monly winced for twenty or twenty-five minutes in a weak solution of substitute and size, by which the fix- ation of the mordant on the cloth is rendered complete. If the mordant is white, the cloth presents little trace of the design when taken from the substitute; the specimen No. 2. shews the appearance which No. 2. X No. 1. acquires by being thus treated. (For an account of the manner of performing this operation, and of the probable action of the dung, see page 306.) 4. After having been well washed, the cloth is ready to be exposed to the dyeing liquor, in which it is kept for two or three hours, being constantly turned by a wince from one compartment of the dye- beck to the other. With madder and some other co- lours the goods are introduced into the cold mixture of water and ground dye-stuff, and heat is then gradually applied by the introduction of steam, until 350 DYEING AND CALICO-PRINTING. the temperature of the liquid is veiy near ebullition (see page 313). When taken out of the dye-beck and simply washed in cold water, the cloth has the appearance of the specimen No. 3. No. 3. 5. The next process to which the cloth is subjected is the " clearing," or the removal of the excess of colouring matter loosely attached to the exterior of the fibres. The processes for this purpose are varied with different dye-stuffs, and even with dif- ferent varieties of the same kind of dye-stuff, accord- ing to their fixity (see page 321). With madder colours, where no sumach is employed, the goods may be cleared in the following manner, having been previously well washed at the dash-wheel : 1. Wince for half an hour in boiling bran-water; 2. Wince for half an hour or more in a dilute so- lution of chloride of soda or chloride of lime ; 3. Boil the goods in soap-water containing half a pound of soap per piece ; 4. Wince a second time in chloride of soda or lime, weaker than before ; CALICO-PRINTING PROCESSES. 351 5. Boil a second time in soap-water. When the goods are dyed with Dutch madder and sumach,* soap cannot be well employed in the clear- ing process, but only bran and chloride of lime or chloride of soda, the latter being preferred. If dyed with the form of madder called garancine (see page 252), neither chloride of lime nor chloride of soda is admissible. Other precautions necessary to be attended to in the process of clearing and the finishing operations to which the calico is afterwards No. 4. subjected have been noticed in the preceding sec- tion. The specimen, No. 4, is the finished cloth. The strength of the mordant, solution of dung substitute, dye-beck, &c., and the details of the pro- cess generally, vary considerably for the same colour- * The tints of cloths dyed in the madder-beck are considerably height- ened by the addition of a small quantity of sumach. One pound of sumach with eighteen or twenty pounds of Dutch madder will dye as much stuff as twenty- four pounds of madder without sumach. The ad- dition of astringent substances to logwood, peachwood, and cochineal, produces a similar result. 352 DYEING AND CALICO-PRINTING. ing matter and mordant, according to the quantity or fullness of the figure, and the depth of its colour. To impart such a stripe as that in the preceding specimen, the bleached cloth may he submitted to the following operations : 1. Printing on mordant of red liquor (of spec, gray. 1'04:2, thickened with a pound and a half of flour to the gallon), and drying by being drawn over steam boxes ; 2. Ageing for three days ; 3. Dunging, 1°, in a mixture of four gallons of dung and three hundred of hot water; and 2°, in a mixture of two gallons of dung and three hundred of hot water ; 4. Wincing in cold water ; 5. Washing at the dash- wheel; 6. Wincing for twenty minutes in a solution of dung substitute and size, made of two quarts of substitute liquor (page 309), one quart of cleansing liquor (page 308), and three hundred gallons of water. 7. Wincing in cold water ; 8. Dyeing in the madder-beck, containing about two pounds of madder per piece of twenty-eight yards ; 9. Wincing in cold water; 10. Washing at the dash-wheel ; 11. Wincing in soap-water, to which some perchlo- ride or nitromuriate of tin has been added ; 12. Washing at dash-wheel; 13. Wincing a second time in soap-water; 14. Wincing in a solution of bleaching powder of spec. grav. 1015 (3° Twad.) CALICO-PRINTING PROCESSES. 353 15. Washing at the dash-wheel ; 16. Drying by the "water extracter" (page 323); 17. Folding; 18. Starching (page 324); 19. Passing through the steam drying machine (page 325). As the quantity of colouring matter which is de- posited on the cloth in the dye-beck is much more dependent on the quantity of fixed mordant on the cloth, than on the strength of the dyeing liquid, a pattern comprising two or more different shades of the same kind of colour may be obtained by the same dye-beck, the cloth having been previously printed with the same kind of mordant at different strengths. The pattern annexed (No. 5) is produced by the No. 5. iron liquor mordant (pyrolignite of iron) at two different strengths, with the same infusion of madder. The mordant for the lilac is iron liquor of spec. 2 A 354 DYEING AND CALICO-PRINTING. grav. about 1-010, thickened with three pounds and a half of British gum to the gallon. The mordant for the dark purple or black is iron liquor of spec. grav. about 1*020, thickened with a pound and a half of flour to the gallon. The two mordants may be printed on at once by the two-colour machine. The finest madder purples are obtained by a mixture of iron liquor with from five to six measures of " pa- tent purple liquor," or " assistant mordant," (see page 294,) thickened with British gum. To produce different shades of red on the same piece from the same madder-beck, the cloth may be printed with red liquor of any density between 3° and 25° Twaddell. The thickener usually employed for red liquor is either flour, starch, or a mixture of equal parts of flour and starch. The proportion of the thickening ingredient is varied according to the No. 6. density of the mordant and the fullness or delicacy of the design ; on the average, a pound and a half may CALICO-PRINTING PROCESSES. 355 be taken for a gallon of liquid. For a weak liquor and for a delicate figure, either British gum or gum arable is substituted for starch or flour. The mordants printed on the cloth for the spe- cimen 1^0. 6 were red liquor of spec. grav. 1-105 for the dark red spots, and the same liquid of spec. grav. 1-021 for the light red figure. Both solutions were thickened with four pounds of British gum to the gallon. British gum is the best thickener for a solution of aluminate of potash. As different mordants form compounds of very different colours with the same dye-stuff, a variety of colours may be communicated to the calico from the same infusion of colouring matter, provided as many kinds of mordants, or mixtures of mordants, No. 7. had been previously applied. The annexed pattern (No. 7), containing a design in black, purple, and two shades of red, was obtained by dyeing the cloth 2 A 2 356 DYEING AND CALICO-PRINTING. at one operation after it had been printed by the four-colour machine with the following mordants : iron liquor of spec. grav. 1-020 for the black ; iron liquor of spec. grav. 1-012 for the purple ; red liquor of spec. grav. 1-042 for the dark red; and red liquor of spec. grav. I'OIO for the pale red. The iron liquor for the black was thickened with a pound and a half of flour to the gallon. The weaker iron liquor for the purple and the two red liquors were thickened with three pounds of British gum to the gallon. After being printed, the cloth was " aged" three days, dunged, dyed with madder, soaped, and cleared in the ordinary manner. To obtain on the same cloth the finest madder reds, purple, and black, it is sometimes better first to print on only the aluminous mordants for the reds, by the two or three colour machine, and then to age, dung, and madder. The strong iron liquor for black, and the weaker iron liquor for purple, may be next grounded in their proper places by hand- blocks, after which the drying, dunging, and mad- dering are repeated. Sometimes the mordants are printed on at difierent operations, but the dyeing is performed in one beck. For example, the mordant for black is printed on first by the single-colour ma- chine, after which the cloth is aged for a day or two; the mordants for the other colours are then grounded in by the hand-blocks, and the ageing, dunging, dyeing, &c. are performed in the usual manner. An endless variety of tints, from red to chocolate, may be obtained from the same madder- CALICO-PRINTING PROCESSES. 357 beck by mixtures of the iron and aluminous mordant in different proportions. Quercitron is a dyeing material well adapted for the madder style of work. With a mordant of red liquor of spec. grav. 8° or 12° Twaddell, thickened with starch, it affords a bright yellow ; with iron liquor of spec. grav. 2° or 3° Twad., thickened with starch, an olive-grey colour ; and with a mixture of the iron and aluminous mordants, a great variety of yellowish-olive tints. To produce a yellow ground with quercitron, the cloth may be padded in red liquor of 10° Twad., and after being dried, aged for two days, and winced in warm chalky water, be dyed in an infusion of quercitron (made of from two to three pounds per piece), containing some glue or size. To get a yellowish-olive figure from the same infusion, the cloth may be printed with a mixture of red liquor at 11°, and iron liquor at 5° Twad., in equal measures, and then dried, aged, dunged, winced in chalky water and dyed. A very good orange is sometimes communicated to cotton goods in this style of work by dyeing in a mixed infusion of madder and quercitron, an alu- minous mordant having been previously applied to the cloth. For a ground, the cloth may be padded in red liquor of 10° or 12° Twad., then winced in warm chalky water, and dyed in a decoction of two pounds of quercitron and a pound and a half of madder per piece. By varying the proportions of the madder and quercitron various shades of orange 358 DYEING AND CALICO-PRINTING. (from golden-yellow to scarlet) may be produced. An endless variety of cinnamon, olive, and fawn coloured tints may be obtained by applying to the cloth mixtures, in various proportions, of red liquor and iron liquor, and by dyeing the cloth in a mixed infusion of madder and quercitron. It is advisable not to have the temperature of the dyeing liquid above 140° or 150° Fahr. Patterns in black and various shades of violet and. purple may be imparted to cotton cloth in the madder style, by means of a decoction of logwood as the dye-stuff, with iron liquor and red liquor as the mordants. To produce a black ground, the cloth may be padded in a mixture of equal measures of red liquor at 8° Twad., and iron liquor at 6° Twad. ; and after having been dried, aged, and winced in chalky water, it may be dyed in a decoction of logwood made from two pounds and a half or three pounds per piece, with the addition of a small quantity of sumach. A grey colour is obtained in the same way by using very weak iron liquor and a weak decoction of the colouring matter; and a vio- let colour, by applying weak red liquor to the cloth. Cochineal is another dye-stuff, the colouring mat- ter of which is capable of being imparted to cloth by the madder style. It is chiefly applied in this way as a ground on which figures are afterwards produced by other styles. To obtain an amaranth- coloured ground, the cloth is padded in red liquor of spec. grav. from 11° to 13° Twad., and after being dried, aged, and winced in chalky water, it is dyed CALICO-PRINTING PROCESSES. 359 in a mixed decoction of cochineal, galls, and bran. A beautiful orange is obtained by a mixture of de- coction of cochineal and decoction of quercitron, with an aluminous mordant; and fine lilacs and violets by decoctions of logwood and of cochineal, with the same mordant. The madder style admits of the application to cloth of the colouring matters of several dye-stuffs besides those which have been alluded to. By combining two or more in the same dyeing liquid, and by varying the mordants, an endless variety of tints may be ob- tained; but a detailed account of such processes could not be included in the limited plan of the present article. II. TOPICAL AND STEAM COLOURS. The mere mechanical part of the process is simpler in this than in any other style of calico-printing. The thickened solution of the colouring matter is ap- plied topically (mixed with the mordant when any is required), in a state fit to penetrate to the interior of the fibre, and after the cloth is dried, the colour- ing matter is fixed, either by exposure to the air or a precipitating agent, or by the action of steam. The operations of dunging, dyeing, and clearing are here altogether omitted. The vegetable colours which may be applied to cotton by this style of work are chiefly those which are not at all, or incompletely, precipitated from their solutions when mixed with a mordant ; the deposition of the insoluble compound of mordant and colouring matter is usually determined in such cases 360 DYEING AND CALICO-PRINTING. by the surface attraction of the tissue, frequently assisted by the application of heat. Not many co- lours applied in this way are remarkable for their permanency. A few topical colours are printed on the cloth in an insoluble state, as pigments, and remain attached principally through the starch or gum used as thickening. The topical colours most extensively used in print- ing cottons are the following : Black. — A very good topical black, known as "chemic black," may be imparted to cotton by means of a mixture of decoction of logwood, copperas, and pernitrate of iron, in the proportions of either of the recipes following : No. 1. 1 gallon of logwood liquor (decoction of logwood) of spec. gi-av. from 6° Tw. to 8° Tw., 4 ounces of copperas, I to ^ gal. (according to the strength of the logwood liquor) of solution of pernitrate of iron of spec. grav. 50° Tw. Thicken with either flour or starch. No. 2. 1 gal. of logwood liquor at 8° Tw., 2 ounces of copperas, 1 pint of solution of pernitrate of iron of 8° Tw., l^lbs. of starch. The logwood liquor, copperas, and starch are boiled together for a few minutes, and when the mixture is cooled to about blood-heat the nitrate of iron is added. This mixture may be printed on the white calico by the roller at the same time as the mordants for colours to be afterwards applied by the madder style. CALICO-PRINTING PROCESSES. 361 After ageing for two days the black colour becomes so permanently attached to the cloth that it is very little affected by the remaining operations of dunging, washing, dyeing, and clearing. Brown. — A very fast topical brown, forming the ground in the annexed specimen (No. 8), may be No. 8. communicated to cotton goods by a solution of ca- techu, mixed with a salt of copper and muriate of ammonia. The following proportions have been re- commended to me by an eminent Lancashire printer: 1^ pounds of catechu, I to 1 gill of solution of nitrate of copper of 90° Tw., 6 to 8 ounces of muriate of ammonia, 1 gallon of water. Thicken with either gum Senegal or British gum. Some printers are in the habit of using a mixture containing much less muriate of ammonia and more nitrate of copper than the above, such as the fol- lowing : 362 DYEING AND CALICO-PRINTING. 1^ pounds of catechu, 3 ounces of muriate of ammonia, 2 quarts of water, 1 quart of pyroligncous acid of 2° Tw., 3 pounds of gum Senegal, and about ^ pint of solution of nitrate of copper of 100° Tw. The catechu and muriate of ammonia are first mixed with the water and pyroligneous acid ; the mixture is then heated and kept at the boiling point for ten minutes, after which it is allowed to settle for half an hour. The clear supernatant liquid is then decanted from the insoluble matters and mixed with the gum Senegal, and when the latter is dis- solved the solution of nitrate of copper is added. The first of the preceding preparations probably deserves a preference. Both of them, like the above topical black, may- be printed on the cloth by the compound machine, with mordants for colours to be applied by the madder style. During the ageing of the goods, the astringent principle of the catechu becomes fixed on the cloth in an insoluble state, but it is usual to complete the fixation of the colouring matter by passing the cloth through a solution of bichromate of potash previous to being dyed in the madder-beck. The specimen Ho. 8 is an example of a design in madder colours on the catechu ground ; the manner of producing such a pattern will be again adverted to, as a part of the process is referable to the resist style of work. The chemical change which takes place during the fixation of the astringent principle of the catechu is the absorption of oxygen. Catechu, or its colouring principle, exists in two forms ; deoxidized and soluble in water, and oxidized and insoluble in pure water, CALICO-PRINTING PROCESSES. 363 but soluble in an aqueous solution of the deoxidized catechu. The form in which catechu is applied to cloth in the above mixtures is as a solution of the oxidized in that of the deoxidized catechu; and the chloride of copper, formed by the reaction of muriate of ammonia on nitrate of copper, acts as a slow oxidizing agent (through the decomposition of water) to the deoxidized catechu. Spirit purple. — For a spirit or fancy* purple, such as that in the following specimen (No. 9), a de- No. 9. coction of logwood, mixed with a tin or an aluminous mordant, is commonly employed. A gallon of logwood liquor of 6° Tw. may be boiled for a few minutes with a pound of starch, and when the mixture is lukewarm, there are added, first, a pint and quarter of solution of per chloride (nitromuriate) of tin at 120° Tw., and afterwards, a quarter of a pint of oil. * AH fugitive topical colours not fixed by steaming are termed spirit, fancy, or wash-off colours. 364 DYEING AND CALICO-PRINTING. This mixture should be carefully stirred before being applied to the cloth. Some printers use a little less tin than is prescribed above, and add a very small quantity of pernitrate of iron. After being printed with this mixture, the cloth should be suspended in a warm room for two days and two nights, and then washed at the rinsing machine. Spirit chocolate. — A fancy chocolate or puce co- lour may be imparted to cotton by means of a mix- ture of logwood liquor, peachwood liquor, perchloride of tin, and a little nitrate of copper, thickened with either starch or British gum. A much faster colour may be obtained by first printing on a mixture of logwood liquor, red liquor, and oxalic acid, and after ageing, passing the cloth through a solution of bichromate of potash. If the materials are employed sufficiently strong, an excel- lent black may be imparted by such a process. The black or chocolate coloured substance thus produced is a compound of oxide of chromium with the colour- ing matter of logwood. Spirit pink. — The following receipt for a topical pink has been recommended to me by a Lancashire printer : 1 gallon of peachwood liquor at 8° Tw., 1^ pounds of starch, ^ gill of solution of nitrate of copper at 100° Tw., 3 gills of solution of perchloride of tin, 4 ounces of " pink salt " (see page 289), and 1 gill of oil. The peachwood liquor is first boiled briskly with CALICO-PRINTING PROCESSES. 365 the starch; the nitrate of copper is next added; and when the mixture is cooled to about blood-heat, the remaining ingredients are introduced. Spirit yellow. — A fancy yellow, pretty much em- ployed for grounding in by the block, is a mixture of decoction of French berries, red liquor, and ox- alic acid, thickened with starch or gum tragacanth. Some printers use, instead of red liquor and oxalic acid, a mixture of perchloride of tin and alum, and thicken with starch; others, perchloride of tin only, with gum as the thickener ; and others, a mixture of red liquor, alum, and protochloride of tin, thick- ened with either flour or starch. Blue. — 1. The following topical blue is sometimes grounded in by the block, for light goods, after all or most of the other colours have been applied. Being easily washed out, it is not used except with fugitive colours, and in cases where it would be inconvenient to apply the mixture for steam blue. 1 pound of yellow prussiate of potash, I5 gills of solution of nitrate of iron of 80° Tw., 8 gills of perchloride of tin of 100°, 1 gallon of water, and I5 pounds of starch. The prussiate of potash is first dissolved in the water, and with this solution the starch is boiled briskly for a few minutes. When the mixture is cooled, the nitrate of iron and perchloride of tin are added. The blue colour is derived fr#ii Prussian blue (see page 256). 2. Indigo communicates a faster blue, so far as 366 DYEING AND CALICO-PRINTING. the action of soap and alkalies is concerned, than Prussian blue; but tlie latter possesses considerably more brilliancy than the former in its ordinary state. As a topical colour, indigo is applied in the form of indigotin, or the hydruret of indigo-blue (see page 244); the deoxidizing agent employed to produce the indigotin being either metallic tin, or the red sul- phuret of arsenic (red orpiment, or red arsenic). Until within a few years, almost the only solution of indigo employed as a topical colour was that known as " pencil blue;" which is prepared by mixing with water and boiling together, about equal parts of ground indigo, orpiment, and quick-lime, and when the mixture is withdrawn from the fire and become lukewarm, adding about as much carbonate of soda as of orpiment previously introduced. The clear liquor when thickened with gum was applied to the cloth by a pencil, or by the block charged with the colour by a particular cdntrivance to prevent as much as possible the access of air to the sieve. 3. A much more convenient way of effecting the conversion of indigo-blue to white indigo, through the action of the same deoxidizing agent, is to mix the ground indigo with a solution (previously made) of red arsenic in perfectly caustic potash or soda, adding as much more caustic alkali as is necessary to keep the white indigo in a state of solution. In this way, the inconvenience arising from the sediment of lime and excess of orpiment is avoided. Pencil blue contains a considerable excess of the deoxidizing %gent, which is necessary on account of the rapidity with which indigo-blue is deposited from all solutions of indigotin when freely exposed to the CALICO-PRINTING PROCESSES. 367 air. With a smaller proportion, the indigo-blue might be deposited in an insoluble state on the sur- face of the cloth before sufficient time is allowed for the solution of indigotin to penetrate to the interior of the fibre. This inconvenience may be partly sur- mounted by directing a jet of coal-gas against the printing roller, and a short length of the cloth pass- ing from the roller. The construction of the cylinder machine, by which pencil blue is applied, dilfers slightly from that re- presented in figure 39, page 336. The cylinder c is dispensed with, the engraved roller itself dipping an inch or two into the colour mixture; and the roller is cleaned from the superfluous colour by re- volving in close contact with one of the sides of the colour-troughs, which thus acts as the " doctor." 4. The deoxidizing agent employed for reducing or affording hydrogen to the indigo in the prepara- tion now commonly substituted for pencil blue, is metallic tin. One equivalent of the metal becomes oxidized, in the presence of a caustic alkali, at the expense of two equivalents of water, the hydrogen of which unites with the indigo. To prepare such a mixture fit for application by the roller, the ma- terials may be employed in the following propor- tions : 4 pounds of ground indigo, 4 quarts of water, 2^ quarts of solution of caustic soda of 70° Tw., 3 pounds of granulated tin. The indigo is first intimately mixed with the water, the tin and alkali are afterwards added, and the mixture is heated to the boiling point, then 368 DYEING AND CALICO-PRINTING. taken off and stirred until a drop, placed on a glass plate, appears of an orange-yellow colour. To this solution is afterwards added a mixture of a solution of chloride of tin at 120° Tw. with an equal measure of muriatic acid, until the free alkali is completely neutralized, and an olive-coloured precipitate falls. The mixture is then well stirred, and added to strong gum- water to the required shade. For some purposes, the free alkali is neutralized by tartaric acid, and from half a gill to a gill of the solution of tin is afterwards added. It is evident that the above preparation contains white indigo in an insoluble state ; in a form, there- fore, unable to enter the interior of the fibres. To dissolve the white indigo and allow it to be absorbed, the printed cloth is passed through a solution of carbonate of soda of spec. grav. 8° or 10° Tw., and at the temperature 80° or 90° Fahr. On afterwards exposing the cloth to the air, the solution of white indigo, now within the fibres, absorbs oxygen and affords a precipitate of indigo-blue. Steam colours. — Very few colours attach them- selves firmly to the cloth by being merely printed on together with the mordant ; but if a cloth thus printed is exposed for a short time to the action of steam, an intimate combination takes place between the tissue, colouring matter, and mordant. Before the printed cloth is exposed to steam, the colouring matter may in general be easily removed by washing with pure water; but afterwards it is attached to the tissues almost as strongly as in any other style of printing, presenting, moreover, a brilliancy and CALICO-PRINTING PROCESSES. 36& delicacy hardly attainable by any other process. Printing by steam is one of the most important of modern improvements in calico-printing; it is prac- tised not only on goods of cotton, but also on silk, woollen cloths, and chalys. The brilliancy and permanency of almost all steam colours are greatly increased by impregnating the cloth with a solution of tin, or, for some styles, with a solution of acetate of alumina, previous to the ap- plication of the colours. The solution of tin now commonly used for this purpose is the stannate of potash^ which is, when properly made, a solution of peroxide of tin in caustic potash (see page 289) ; this preparation sometimes contains protoxide of tin, but the stannate containing the peroxide only is pre- ferred. This alkaline solution is not nearly so inju- rious to the cotton fibre as the perchloride. After having been padded in the solution of stan- nate of potash, the pieces of cotton are usually passed through a cistern containing a Solution of muriate of ammonia, to produce a precipitate of peroxide of tin. Some printers employ very dilute sulphuric acid instead of a solution of muriate of ammonia, but the latter is decidedly preferable. To the cloth thus prepared, or occasionally with- out any preparation except bleaching, the solutions of the mixed colouring materials and mordants, pro- perly thickened, are applied either by the roller or block. Steam colours are chiefly grounded in by the block to cloths which have been already printed and finished off according to other styles of work, particularly the madder style. The following recipes 2 B 370 DYEING AND CALICO-PRINTING. will afford examples of the principal mixtures whicli are applied to cotton as steam colours ; some of them may also be applied to silk and woollen goods, but for this purpose the proportions of the materials generally require to be varied. The mordant most frequently used for steam colours is red liquor, mixed with oxalic or some other acid to prevent the precipi- tation of the compound of colouring matter and mor- dant. Steam black. — The first of the mixtures follow- ing is best adapted for the roller, the other for grounding in by the block : No. 1. 1 pint of red liquor of 18° Tw., 2 pints of iron liquor of 24° Tw., 1 gallon of logwood liquor of 8° Tw., If pounds of starch, 1| pints of pyroligneous acid of 7° Tw. All these materials may be mixed promiscuously and then boiled for a few minutes to form a mucilage. The cotton requires to be steamed about thirty mi- nutes. No. 2. 3^ pints of peachwood liquor of 6° Tw., 7 pints of logwood liquor of 6° Tw., 12 ounces of starch, 14 ounces of British gura, 3 ounces of sulphate of copper, 1 ounce of copperas, 3 ounces of a neutral solution of pernitrate of iron, made by mixing one pound of acetate of lead with three pounds of the common acid nitrate of iron of 122° Tw. If intended for goods of silk and wool, four ounces of extract of in- digo should be added. CALICO-PRINTING PROCESSES. 3Y1 The logwood liquor and peachwood liquor are mixed and divided into two equal portions, one of which is boiled for a short time with the starch, and the other with the British gum. The two liquids are afterwards mixed, and the remaining ingredients are added; the nitrate of iron being introduced last, and not before the mixture is cold. Steam red. — The best steam red for cotton is obtained by decoction of cochineal, with oxalic acid and protochloride of tin. The mixture obtained according to the following receipt may be applied either by the roller or block : 1 gallon of cochineal liquor of 6° Tw., 1 pound of starch, 3 ounces of oxalic acid, 4 ounces of cryst. protochloride of tin. The cochineal liquor is first boiled with the starch for a few minutes; when the mixture is half cold, the oxalic acid is added, and as soon as the acid is dissolved the salt of tin is introduced. A cheaper but less brilliant steam red, much used by some printers, is prepared by substituting peach- wood liquor for cochineal liquor in the above. Steam purple — To a gallon of red liquor of 18° Tw., heated to about 140° Fahr., three pounds of ground logwood are added ; the mixture is well stirred for about half an hour, and then strained through a cloth filter, the residue on the filter being washed with two quarts of hot water, which are re- ceived into the first liquid. The mixture thus ob- tained may be diluted with water, according to the 2 B 2 372 DYEING AND CALICO-PRINTING. shade of colour required ; for a moderate depth, one measure may be mixed with three of water, and thickened with starch, flour, or gum. This prepa- ration may be applied either by block or roller. Steam Either decoction of Persian ber- ries, decoction of quercitron, or decoction of fustic, may be used as a steam yellow, but the first is most commonly employed at present. No. 1. 1 gallon of berry liquor of 4° Tw., 5 ounces of alum, thickened with about 14 ounces of starch. No. 2. 1 gallon of berry liquor of 4° Tw., li gill of red liquor of 18° Tw., 2 ounces of crystals of protochloride of tin, and about 14 ounces of starch. The mixture made according to the following re- ceipt afibrds a darker shade than either of the pre- ceding : No. 3. 1 gallon of a mixture of equal measures of decoction of Persian berries at 15° Tw., and of decoction of fustic at 15° Tw., 14 ounces of starch, 7 ounces of alum, 7 oimces of crystals of protochloride of tin. The decoctions of the dye-stuffs are mixed with the alum and starch, and heated until properly thick- ened; the mixture should be soon withdrawn from the fire, and when cold mixed with the salt of tin. The preparation made as No. 2 will probably be found superior to either of the others for cotton goods. The steaming for No. 3 must be continued only a short time, else the fibre of the cotton would CALICO-PRINTING PROCESSES. 373 be apt to become corroded by the salt of tin. This preparation is better adapted (as a steam colour) for- fabrics of wool and silk than for those of cotton, but it may be advantageously applied to cotton as a spirit or wash-off colour (page 363). The orange stripe in the specimen annexed (No. No. 10. 10) is also produced by decoction of Persian berries, the mordant being protoxide of tin only. A convenient mixture for producing this colour is the following : 1 gallon of berry liquor made from three pounds of berries to the gallon, and 4 ounces of cryst. protochloride of tin. Boil together for a few minutes and thicken with 3 to 4 pounds of British gum or I pound of starch. The cloth may be steamed and washed in the usual manner, but this colour becomes strongly at- tached by merely ageing the cloth for two or three days, and then passing it through hot chalky water. 374 DYEING AND CALICO-PRINTING. Steam blue. — A very beautiful steam blue may- be communicated to cotton and woollen goods by- means of a mixture of yellow or red prussiate of potash, with tartaric, oxalic, or sulphuric acid, and alum or perchloride of tin. If for applying to cot- ton goods, alum is used; but if for woollen fabrics, perchloride of tin is preferable. The blue in the annexed specimen (No. 11) was produced by such a process. No. 11. For printing on cottons by the roller, either No. 1 or No. 2 of the following mixtures may be used: No. 1. 1 gallon of water, \\ pounds of yellow prussiate of potash, 3 to 4 ounces of alum, 5 to 6 ounces of oil of vitriol, 1| pounds of starch. No. 2. 1 gallon of water, 1^ pounds of yellow prussiate of potash, 3 to 4 ounces of alum, 10 to 12 ounces of tartaric acid, Ig pounds of starch. CALICO-PRINTING PROCESSES. 375 The starch and prussiate of potash are boiled in the water, and when the mixture is withdrawn from the fire and cooled, the sulphuric or tartaric acid and alum are introduced. The mixture made as No. 2 affords a more lively colour than that made as No. 1, but the latter is least expensive. No. 3. 1 gallon of water, 3 to 3| ounces of alum, 1^ to 2 ounces of oxalic acid, 3 to 4 ounces of tartaric acid, 20 ounces of gum, 12 ounces of yellow prussiate of jjotasli. The gum, acids, and alum may be first dissolved in the water with the assistance of heat, and when the mixture is quite cold, the prussiate of potash is added. The time necessary for steaming cottons printed with either of these preparations is about thirty minutes. When withdrawn from the steaming cy- linder or chamber, the goods present, if yellow prus- siate of potash is used, a blueish-white colour, which changes to deep blue on exposure to the air for a couple of days. The chemical change by which the colour is produced during the exposure to air depends on the absorption of oxygen or the removal of hydro- gen ; as is evident from the circumstance, that if the goods are passed through a solution of bichromate of potash as soon as withdrawn from the steaming cylinder or chamber, the blueish-white changes to deep blue immediately. If the red prussiate of pot- ash is employed instead of the yellow prussiate, the cloths acquire the proper blue colour during 376 DYEING AND CALICO-PRINTING. the steaming, and the depth of the colour is not sensibly increased by exposure to air or to a solu- tion of bichromate of potash. The blue colouring matter produced in these pro- cesses is a variety of Prussian blue, formed through the decomposition of hydroferrocyanic acid set at liberty by the action of the more powerful acids present on the prussiate of potash. When an aque- ous solution of pure hydroferrocyanic acid is gently heated and exposed to the air, the acid suffers decom- position with formation of hydrocyanic or prussic acid, and Prussian blue, which precipitates. Assum- ing the composition of the Prussian blue thus formed to be the same as that produced by mixing a solu- tion of yellow prussiate of potash with a solution of a salt of the peroxide of iron, (which contains cy- anogen and iron in the proportion of nine equiva- lents of the former to seven equivalents of the lat- ter,*) the decomposition which the hydroferrocyanic acid experiences appears to be after the following manner: seven equivalents of the acid, containing twenty-one equivalents of cyanogen, seven equiva- lents of iron, and fourteen equivalents of hydrogen, afford, 1°, one equivalent of Prussian blue, contain- ing seven equivalents of iron and nine equivalents of cyanogen; 2°, twelve equivalents of hydrocyanic acid; and 3", two equivalents of hydrogen to be removed by /fin oxidizing agent. This decomposition may be ex- pressed more simply in symbols ; thus, * The prussiate of potash which enters into the composition of this variety of Prussian blue may be neglected in the above calculation. CALICO-PRINTING PROCESSES. 377 7 eqs. of liydrofeiTOcyanic acid (Hj + Fe Cy^) or H,^ Fe^ Cy^, produce 1 eq. Prussian blue Fe^ Cyg 12 eqs. hydrocyanic acid H,2 Cji^ 2 eqs. hydrogen Such we may suppose to be the decomposition which takes place when an aqueous solution of hydro- ferrocyanic acid is heated with exposure to the air. That the reactions which occur in the steam blue process are somewhat different from the above, how- ever, is pretty evident from the circumstance that the colour does not appear until the cloth is exposed to a source of oxygen, although the acid is cer- tainly decomposed during steaming, as is manifest from the odour of hydrocyanic acid then developed. According to another, and a more consistent, view of these changes, the blueish-white compound on the steamed cloth, before being exposed to the air, is the same as the precipitate which falls on mix- ing a solution of yellow prussiate of potash with a solution of a salt of the protoxide of iron. This precipitate contains, besides a certain proportion of prussiate of potash, iron and cyanogen in an equal number of equivalents. When exposed to the air, it absorbs oxygen and becomes deep blue ; the oxygen thus absorbed combines with a portion of the iron in the precipitate, forming peroxide of iron, which remains as an essential part of the Prussian blue. As the blueish-white precipitate contains a com- pound of an equal number of equivalents of iron and cyanogen united with prussiate of potash, it may be formed from a mixture of prussiate of potash 378 DYEING AND CALICO-PRINTING. and hydroferrocyanic acid, with the separation of nothing more than hydi^ocyanic acid ; thus, From 9 eqs. of hydroferrocyanic acid = H,g FCg Cy^^ Deduct 18 eqs. of hydrocyanic acid = Cy,g There remains . . . . . Fcg Cyg On exposure to the air, this compound of iron and cyanogen, the probable constitution of which is represented by the formula Fe6 + 3(FeCy3) ab- sorbs three equivalents of oxygen, and thereby af- fords a compound of peroxide of iron with the variety of Prussian blue noticed in the preceding page. The formula for this compound is Fcg O3 -h (re4 + 3(Fe The reactions which occur when the red prussiate of potash is employed are different, the acid liberated from that salt by the action of the stronger acids not having the same composition as hydroferrocyanic acid. The composition of hydroferridcyanic acid (the acid liberated from the red prussiate) is such as to allow of the decomposition of the acid into Prussian blue, hydrocyanic acid and cyanogen, with- out the interference of atmospheric air or any other source of free oxygen. In its present form, this beautiful colour has not been long in general use for application to calicos. The colour obtained by the mixture formerly em- ployed, consisting of prussiate of potash with tartaric or sulphuric acid, without any addition of perchloride of tin or alum, is always lighter in shade and less vivid than that obtained with such an addition, how- ever concentrated the solution of prussiate of potash. The acids in the mixture, including the sulphuric CALICO-PRINTING PROCESSES. 379 acid of the alum in combination with alumina (namely three equivalents for one equivalent of alum), should be in sufficient quantity to neutralize one equiva- lent of alkali for every two-thirds of an equivalent of prussiate of potash; or to saturate 5'9 ounces of anhydrous potash for 18 ounces of the prussiate. Steam green. — A very good steam green may be communicated to cotton goods by combining the ma- terials for producing a yellow, with the preceding mixture for -steam blue; thus, 1 gallon of berry liquor made from a pound and a half of Persian berries (or of 4° Tw.), 12 ounces of yellow prussiate of potash, 3 to 4 ounces of crystals of protochloride of tin, 5 to 6 ounces of alum, 3 to 4 ounces of oxalic acid. Thicken with gum. The oxalic acid, the muriatic acid derived from the salt of tin, and the sulphuric acid united with alumina in the alum, should form, together, one equivalent, or a quantity sufficient for the saturation of one equivalent of a protoxide for every two-thirds of an equivalent of the prussiate. The time required for steaming this colour is about thirty minutes. After the colour mixtures are printed on, the calico is dried in a warm atmosphere for two days or thereabouts before being exposed to the action of the steam. Different methods of applying the steam are practised in different print-works. In some the goods are introduced into a large stout deal box, the lid of which is made very nearly steam-tight by edges of felt. The steam is admitted near the bottom 380 BYEING AND CALICO-PRINTING. by a thickly perforated pipe which traverses the box. For the deal box is sometimes substituted a small chamber built of masonry, about four or five feet in length, by three feet in width, and three feet in height. The cloth is suspended free from folds, on strings across the chamber. The most common method of applying the steam is the following. Three or four pieces of the printed and dried calico are stitched together at the ends and coiled round a hollow cylinder of copper, about three feet in length and four inches in diameter, and perforated with holes about one-twelfth of an inch in diameter and half an inch distant from each other. One of the ends of the cylinder is open, to admit the steam ; the other is closed. The calico is prevented from coming immediately into contact with the cy- linder by a roll of blanket stuff, and is covered with a piece of white calico tightly tied around the roll. During the lapping and unlapping of the calico the column is placed horizontally in a frame, in which it is made to revolve; but during the steaming it is fixed upright, and supplied with steam through its bottom from the main steam boiler of the works, the quantity admitted being regulated by a stopcock. During the whole process the temperature of the steam should be as near 211° or 212°, as possible: the condensation which takes place below that de- gree is apt to cause the colours to run ; but a higher temperature is also injurious, as a slight condensa- tion, sufficient to keep the goods always moist, is essential to the success of the process. The steam- ing is continued for from twenty minutes to three quarters of an hour, according to the nature of the CALICO-PRINTING PROCESSES. 381 stufF and the colouring mixture. The usual time with cottons is twenty-five minutes, and with de laines about thirty or thirty-five minutes. The time required for steaming cotton goods by the chamber is longer than what is required by the column, being generally about an hour. When the steam is cut off", the cloths should be immediately unrolled to pre- vent any condensation : they are then soft and flac- cid, the material used as a thickener for the colours being in a semi-fluid state; but on exposure to the air for a few seconds only, the thickener solidifies, and the goods become perfectly dry and stiff. After the pieces have been aged for a day or two, the thickener is separated by a gentle wash in cold water. To produce with steam colours only such a pat- tern as the annexed (No. 12), containing a design in lilac, pink, red, yellow, black, and dark orange red, the cloth may be printed by the five-colour ma- chine in the following manner : No. 12. *. 382 DYEING AND CALICO-PRINTING. By the first roller, with a mixture of logwood liquor, starch, and solution of tin for producing the lilac ; By the second and third rollers, with the mixtures for the pink and red (see page 371), one containing weaker cochineal or peachwood liquor than the other ; By the fourth roller, with the mixture for the yellow (see page 372) ; By the fifth roller, with the mixture for steam black (see page 370). The dark orange red results from the mixture of the red with the yellow. After being steamed, the cloth is aged in a warm room for two days and two nights, and then washed at the rinsing machine. The style following, for producing a design in black, red, brown, green, and yellow on a white ground, is a combination of the madder style with a topical brown and steam colours, which is sus- ceptible of a great variety of interesting modifi- cations. 1. The cloth is printed by the three-colour ma- chine in the following manner : with iron liquor, for black, by the first roller ; with red liquor by the second roller, and with catechu brown (page 361) by the third roller. 2. After being printed, the cloth is aged for two days, dunged, dyed in the madder-beck, and cleared. 3. The cloth is lastly printed by the block with the mixtures for steam green (page 379), and steam yellow (page 372), then steamed, aged, and washed. By a similar series of operations, a design may be CALICO-PRINTING PROCESSES. 383 imparted in black, brown, lilac, pink, green, blue, orange, and yellow, on a white ground. The cloth is first printed by the four-colour machine with iron liquior of two strengths, one for the black, the other for the lilac ; with red liquor for the pink, and with the mixture for catechu brown (page 361). After betng aged, dunged, dyed with madder, and cleared as usual, the cloth is printed by the block with the mixtures for steam blue (page 374), and steam yellow (page 372), and then steamed in the ordinary man- ner. To produce the orange, the steam yellow is printed on a part of the pink, and the green results from the mixture of some of the yellow with the blue. The specimen No. 10, page 373, is an example of the combination of madder colours with steam colours ; for the red and chocolate stripes, the cloth was printed with red liquor and the mixture of red liqiuor with iron liquor, and after dunging, dyeing, and clearing in the usual manner, the mixture for steam orange was applied by the block. 3. MINERAL COLOURING MATTERS. Mineral colouring matters are adapted, not only to the production of designs on a white or coloured ground, but also to form a ground for the reception of a design in other colours. To impart the colour to the entire surface of the cloth, the latter may be impregnated successively, by the padding machine, with the two solutions necessary to produce the colour, or else the cloth may be padded in one of the solutions and be afterwards winced in the other. 384 DYEING AND CALICO-PRINTING. To produce a design in a mineral colouring matter on a white or coloured ground, the cloth is usually first printed with one of the solutions, and then either padded or winced in the other. The common " padding machine," by which a cloth is uniformly imbued with a liquid, is much the same as the starching machine (fig. 37, page 324), the thickened liquid being contained in the trough a. A simpler padding machine is employed in some print-works, of which fig. 41 is a representation : a Fig. 41. and h are two cylinders revolving in close contact ; h is covered with blanket stuff, and dips partly into a trough which contains the liquid slightly thickened. The calico is first rolled around the cylinder c, and then passed in the direction of the arrow between the cylinders a and h. As soon as the calico is padded, it is dried hard, by exposure to a temperature of 212° or thereabouts, either by being drawn over a series of sheet-iron boxes heated by steam, or through the steam drying machine de- scribed at page 325, or through the hot-flue. If the colour is to be applied to the face of the cloth only, and not to both face and back, the common printing machine with a roughened roller is substi- tuted for the padding machine. Prussian blue. — More than one method of apply- ing this colouring material to cloth has already been noticed; another is by the consecutive application of either yellow prussiate of potash and a salt of the CALICO-PRINTING PROCESSES. 385 peroxide or protoxide of iron, or red prussiate of potash and a salt of the protoxide of iron. The latter method is very rarely practised. To impreg- nate the entire surface of a piece of cloth with Prus- sian l)lue, it may be treated in the following manner : 1°. Pad in a solution of acetate and sulphate of iron made by adding three pounds of acetate of lead to a solution of four pounds of copperas in a gallon of water, decanted from the precipitated sulphate of lead and diluted to the density 2° or 3° Tw. 2". Dry the cloth, and then wince it in warm chalky water. 3". Wince it in a solution of a pound of yellow prussiate of potash in forty gallons of warm water, to which are added four ounces of oil of vitriol. To produce a design in Prussian blue by this style of work, the cloth may be printed with the mixed solution of acetate and sulphate of iron, made as above, of spec. grav. 4° or 5° Tw., thickened with gum and "sightened" by the addition of a little prussiate of potash. After being aged, the cloth is winced in chalky water, cleaned, and winced until it acquires the desired shade in a solution containing three or four ounces of prussiate of potash, and one fluid ounce of muriatic acid per piece. Chrome-yellow. — The yellow and orange in the specimen annexed (No. 13) are produced by the two chromates of lead, chrome-yellow and chrome- orange. To impart a ground of chrome-yellow to a piece of calico, the cloth should be padded with a solution of two pounds of acetate of lead in a gallon of water 2 c 386 DYEING AND CALICO-PRINTING. No. 13. pi containing a little size, then dried, passed first through a weak solution of carbonate of soda, and afterwards through a solution of bichromate of pot- ash. Rinse and dry. To apply chrome-yellow topically, the cloth may be printed with a solution containing both acetate and nitrate of lead (from seven to ten ounces of each to the gallon) thickened with starch. After being printed and dried, the cloth is winced first in a weak solution of carbonate of soda, and afterwards in a solution of bichromate of potash containing about two ounces per piece. To clear the whites, the cloth may be winced in water slightly acidulated with muriatic acid. Chrome-orange. — A ground of chrome-orange may be communicated to a piece of cotton by first apply- ing chrome-yellow in the ordinary manner, and then exposing the cloth to boiling lime-water, which with- draws a portion of the chromic acid from the chrome- yellow and leaves chrome-orange : thus. CALICO-PRINTING PROCESSES. 387 1. Pad the cloth twice in a saturated solution in water of acetate and nitrate of lead, in the proportion of a pound of the nitrate to a pound and a quarter of the acetate.* Dry in the hot-flue. 2. Wince in weak milk of lime for a few minutes. 3. Wince in a warm solution of bichromate of potash containing five or six ounces per piece; and lastly, 4. Wince in boiling milk of lime. Rinse and dry. To produce a design in chrome-orange on a white ground, the cloth may be printed with a saturated solution of acetate and nitrate of lead (as above) thickened with British gum; after being dried, it is passed through a solution of sulphate of soda to fix the oxide of lead in an insoluble state, then well washed in water, and winced in a warm solution of bichromate of potash. It is afterwards rinsed, and passed through boiling milk of lime to convert the chrome-yellow into chrome-orange. A design in chrome-yellow on a chrome-orange ground may be obtained by printing an acid on the orange ground, so as to withdraw the excess of oxide of lead from the subchromate (orange), and thus form the neutral chromate (yellow). The specimen No. 13 was produced in this way; the blue and black are merely spirit colours. Different shades of green are given to cotton goods by a mixture of chrome-yellow with Prussian blue. The colouring materials may be applied consecutively, or at once from mixed solutions; the cloth being * Water is capable of dissolving nearly twice as much of a mixture of acetate and nitrate of lead, in the jiroportion of single equivalents, as of either of the salts separately. 2 c 2 388 DYEING AND CALICO-PRINTING. first padded, in the latter case, with a mixture of acetate of iron and nitrate of lead, and afterwards winced in a solution of prussiate of potash and bi- chromate of potash with a small quantity of muriatic acid. To obtain a design of a green colour by conjoin- ing chrome-yellow with indigo-blue, the cloth may be printed with a solution of from two pounds to two pounds and a half of nitrate of lead in a gallon of the neutralized mixture of white indigo with so- lution of tin prepared as described at pages 367, 368. After being printed, the cloth is passed, first, through a warm solution of carbonate of soda to fix the blue and oxide of lead, and afterwards through a solution of bichromate of potash to raise the yellow. Iron huff. — The solutions of iron in common use for iron buff are the pernitrate and a mixture of the acetate with the protosulphate, obtained by adding from one part to three parts of acetate of lead (pyro- lignite) to three parts of copperas. Double decom- position takes place between the acetate of lead and a portion of the copperas with formation of acetate of iron and sulphate of lead. For producing light shades, alum is sometimes added, together with a little carbonate of soda to take up a portion of the acid of the alum. Acetate of lime is frequently sub- stituted for acetate of lead, in the preparation of " buff-liquor." The buff colour in the specimen following (No. 14) is produced by iron buff. To impart a buff ground, the pieces are padded in CALICO-PRINTING PROCESSES. 389 No. 14. bufF-liquor of any strength between 2° and 10° Tw., according to the shade of colour desired, then dried by being drawn either through the hot-flue or over iron boxes filled with steam, and aged for one or two days. Some printers then wince the pieces in water containing some chalk, and afterwards pass them through a solution of carbonate of soda; but it is much better to pass them at once through a solu- tion of caustic soda, or through milk of lime. During the ageing of the padded goods the salts of the protoxide of iron become subsalts of the per- oxide, which are decomposed in the alkaline or cal- careous solution, the acids being withdrawn by the alkali while the peroxide of iron becomes fixed on the cloth. To obtain an iron buff figure, the pieces may be printed with a buff-liquor of any strength between 10° and 30° Tw. thickened with either gum, calcined farina, salep, or British gum. After being dried and aged, the pieces are passed directly through a so- 390 DYEING AND CALICO-PRINTING. lution of caustic soda, or else tlirough milk of lime. Manganese bronze. — The brown ground of the specimen annexed (No. 15) is produced by manga- nese bronze or peroxide of manganese. No. 15. A solution of manganese sufficiently pure for pro- ducing the bronze, may be obtained from the residue of the process for chlorine, by saturating the remain- ing free sulphuric or muriatic acid with chalk, allow- ing the precipitate to settle, and decanting and con- centrating the clear supernatant liquid. The chalk serves not only to saturate the free acid, but to pre- cipitate peroxide of iron from the soluble salts of that oxide which this bye-product always contains. Lime has been recommended for this purpose instead of chalk, but it is never employed on the large scale, as an excess would decompose the salts of manga- nese as well as those of iron; an excess of chalk, however, is without action on the manganese salt. CALICO-PRINTING PROCESSES. 391 A purer solution of manganese is prepared by heat- ing the residue of the chlorine process with more black oxide of manganese until the evolution of chlorine almost ceases, and then adding, either chalk, or freshly precipitated carbonate of manganese, until the liquid becomes colourless. Having been allowed to settle, the solution is decanted and concentrated by evapora- tion. To impart a dark brouze ground such as that in the above specimen, the strength of the solution of chloride of manganese may be about 26° Twad. For lighter shades, the solution may be made as weak as 4° Twad. After having been padded and dried, the goods are passed through a cold caustic ley, whereby prot- oxide of manganese becomes precipitated on the cloth. On exposure to the air, the protoxide soon absorbs oxygen, passing into the state of the brown peroxide ; but the peroxide may be produced immediately by wincing the goods in a solution of chloride of lime or chloride of soda as soon as they are taken out of the caustic ley. The common practice is to expose the pieces to the air until they acquire a good full colour, and then to complete the peroxidation of the manganese by a dilute solution of chloride of lime. Peroxide of manganese is very seldom applied as a figure on a white ground. The solution of the chloride used for this purpose may have a density about 16° Tw., and be thickened with from two pounds to two pounds and a half of gum to the gal- lon. A small quantity of tartaric acid is a useful addition to such a solution. The printed and dried cloth is drawn through a caustic ley, exposed to the 392 DYEING AND CALICO-PRINTING. air, and winced in a solution of chloride of lime as above. Scheele's green. — To obtain a ground of Scheele's green (arsenite of copper), the cloth is padded two or three times with a solution of nitrate of copper, or else with a mixture of the sulphate and acetate containing a little size, and after being dried, is winced in a dilute solution of a caustic alkali, to fix the oxide of copper. The cloth is then rinsed in water and winced in a dilute solution of arsenious acid, or else in a solution of arsenite of soda. For the manner of applying a few other mineral colours, namely, antimony orange, arseniate of chro- mium, orpiment, and prussiate of copper, see page 254, et seq. Mineral colours are frequently combined with steam and madder colours in the same design. When this is the case, the madder colours are always applied first, the mineral colours next, and the steam colours last. The following method of procuring a design in black, purple, two shades of red, two shades of buff, green and yellow, on a white ground, is an example of the combinations of mineral colours with madder and steam colours : 1. Print the cloth by the four-colour machine with the mordants for black, purple, and two reds (see pages 353 and 354) ; 2. Age, dung, dye in the madder-beck, clear and dry; 3. Print by the two-colour machine (or else by CALICO-PRINTING PROCESSES. 393 blocks, according to tlie design) with bufF-liquor of two strengths, thickened with starch or British gum ; 4. Wince the cloth, after being aged, in milk of lime, to raise the buff, and rinse in water ; 5. Dry and print by blocks with the mixtures for steam blue (page 374), and steam yellow (page 372); 6. Age, steam, and rinse. A pleasing pattern may be obtained by combining in one design, on a white ground, figures or bars in different shades of iron buff, with a figure or stripe in steam blue. The buffs are first applied in the usual manner. 4. RESIST STYLE. The object of the resist style of work is to pro- duce a white or coloured design on a coloured ground by the topical application, in the first place, of a substance called the resist^ reserve^ or resist paste, which has the property of preventing the attachment or developement of colour, when the whole surface of the cloth is afterwards impregnated with a dyeing material. One class of resists, consisting of sub- stances of an unctuous nature, acts merely mechani- cally; another class acts both mechanically and che- mically. The latter kind are divisible into two subdi- visions, according as their influence is exerted merely on the mordant or on the colouring matter itself. 1. Fat resists. — Resists of an unctuous nature are chiefly used for applying to goods of silk and wool, 394 DYEING AND CALICO-PRINTING. but they may be also advantageously applied, in particular circumstances, to goods of cotton. The annexed specimen (No. 16) is an example of the No. 16. combination of such a style of work with madder colours and steam colours. The specimen No. 7, page 355, shews the appearance of the above in an early stage of the process. After having been printed, dyed, and cleared as already described, the red and lilac figures are covered (or overlaid) with a resist consisting, usually, of an intimate mixture of suet and gum-water.* The whole is then run over by the roller with weak iron liquor for the lilac ground, and the cloth is aged, dunged, dyed, and cleared. The mixtures for steam green and steam yellow are afterwards pegged in by blocks, and the steaming is performed in the usual manner. The * A solution of citrate of soda (obtained by neutralizing lime-juice with soda), thickened with pipe-clay and gum, might be used instead of the mixture mentioned in the text. CALICO-PRINTING PROCESSES. 395 mixture for the green in the above specimen is quite similar to that described at page 379; that for the yellow was made by mixing a quart of red liquor of spec. grav. 8^° Tw. with a gallon of berry liquor of 2° Tw. In this style of work, however, the dyeing with madder might as well be performed at one opera- tion, as the red and lilac mordants for the figures are not at all injured by the fat resist with which they are covered. 2. Resists for mordants. — The material generally used for preventing the deposition of a mordant on particular parts of the cloth is an acid or acidulous salt capable of uniting with the base of the mordant, to form a compound soluble in water and not decom- posable into an insoluble subsalt during the hanging of the mordanted goods, previous to dunging and dyeing. The resist commonly employed for the iron and aluminous mordants is lemon-juice or lime-juice, or a mixture of one of these with tartaric and oxalic acids and bisulphate of potash. The thickening ma- terial is either a mixture of pipe-clay or china-clay with common gum, a mixture of British gum with gum Senegal, or British gum alone. Lemon-juice or lime-juice is decidedly preferred to pure citric acid (which is the acid principle of these juices), as the mucilaginous matters in the former impede the crys- tallization of the acid within the pores of the cloth, and thus render it better adapted to prevent the at- tachment of the mordant in an insoluble form. The strength of the resist is regulated by the strength of the mordant afterwards applied it is seldom used of a higher density than 2° Twad. 396 DYEING AND CALICO-PRINTING. The specimen (No. 17), exhibiting a design in black, lilac and white on a lilac ground, was produced No. 17. by adapting the resist style of work to madder colours. The printing for such a pattern may be performed by the three-colour machine in the following order : By the first roller ; the resist, which may be either lemon-juice of spec. grav. 2° or 3° Twad., thickened with four pounds of British gum to the gallon, or else a solution of about the same density, of tartaric and oxalic acids in weaker lemon-juice, also thickened with British gum : By the second roller; the mordant for the black, which is iron liquor of spec. grav. 8° Twad., thick- ened with a pound and a half of flour to the gallon : By the third roller; the mordant for the ground of lilac, which is iron liquor of spec. grav. 1^° Twad., thickened with four pounds of British gum to the gallon. The application of the mordant for the ground may be made by the padding machine (fig. 41, page CALICO-PRINTING PROCESSES. 397 384), but it is commonly done by the cylinder ma- chine, the entire surface of the copper roller being slightly roughened or engraved in close diagonal lines, so as to enable it to afford an uniform deposit on the cloth. The operations of ageing, dunging, dyeing, and clearing are conducted in much the same manner as if the acid resist had not been applied. It is usual, in this style of work, to add a small quantity of chalk to the dung-beck, in order to counteract the effects of the free acid in the resist. Iron liquor may be resisted or prevented from affording a deposit of insoluble subsulphate during the ageing, by a process somewhat different from the above, the resisting agent being protochloride of tin (commonly called salts of tin), instead of a free acid or an acidulous salt. A mixture of protochloride of tin and iron liquor does not afford a deposit of a subsalt of iron during the ageing of cottons printed with the mixture, probably through the occurrence of a double decomposition with formation of acetate of tin and chloride of iron. The latter compound does not afford an insoluble precipitate during the ageing, and may be entirely removed from the cloth by washing. When a piece of cotton cloth is printed with a solution of salts of tin by the first roller of a two- colour machine, and with iron liquor by the second roller, over the parts printed by the first roller, such a mixture as the above is of course formed wherever the salt of tin had been applied, and no subacetate of iron is deposited there during the ageing. 398 DYEING AND CALICO-PRINTING. The protochloride of tin, however, is never applied in this way with a view of producing a white figure on a coloured ground; it is commonly mixed with red liquor, as the deposition of the insoluble sub- sulphate of alumina from that preparation is not interfered with by the protochloride. After a piece of cloth thus printed has been aged, dunged, dyed in the madder-beck, and cleared, it therefore pre- sents a red figure surrounded by purple or lilac. It is to be observed that this method of procedure is only followed when a better definition of the red de- sign is required than could be attained by leaving a blank figure in the roller for the iron liquor, and afterwards printing the red liquor on the white parts either by a second roller or by the block. To resist weak iron liquor and impart the mordant for a full red with madder, the mixture may have the follow- ing composition : 1 gallon of red liquor of 18° Twad., 4 oz. crystals of protochloride of tin ; with a sufficient quantity of British gum or a mixture of British gum and starch as the thickener. To obtain a design in full red and black on such a lilac ground as the specimen No. 16, page 394, contains, the cloth is printed with strong iron liquor for the black, with the above mixture for the red, and with iron liquor of 1° Twad. for the lilac ; after which it is aged, dunged, dyed, &c. in the usual manner. A great variety of pleasing effects may be produced by combining this kind of work with steam or topical colours, the iron liquor not being applied as a ground, but as a design extending on each side of the red figure, and on the parts left CALICO-PRINTING PROCESSES. 399 white the steam colours are applied, after dyeing with madder and clearing. Another material, much used as a resist for red liquor and iron liquor, is a solution of citrate of soda, prepared by neutralizing lime-juice of about 4° Twad. with soda, thickened with a mixture of gum and pipe-clay. The action of this resist may probably be referred to the tendency of citric acid, like oxalic acid and a few others, to form a double salt with peroxide of iron or alumina and an alkali, which alfords no precipitate of alumina or oxide of iron during the ageing. In this case a portion of the alkali in the neutral citrate is withdrawn by the acetic acid in the mordant, an acid citrate of soda being thus formed. Neutralized lime-juice of 4° Tw. has about the same resisting power as the unneu- tralized juice of 2° Tw. The principal use of neutralized lime-juice as a resist for iron liquor is to protect figures previously applied in madder colours ; for which purpose the free acid is quite inapplicable, as it would dissolve the mordant on the cloth in combination with the colour- ing matter. If the dyeing of the cloth with madder for such a pattern as that of the specimen No. 16, page 394, is performed at two operations, neutra- lized lime-juice is generally preferred to the fat resist for protecting the red, lilac and white figures of the specimen No. 7, page 355 ; but if the maddering is to be completed at one operation, the fat resist must be used. 3. Resists for the colouring matter. — The pro- duction of a white or coloured pattern on a coloured 400 DYEING AND CALICO-PRINTING. ground by tlie direct action of a resist on a colour- ing matter, is chiefly practised with indigo, at least in the printing of calicos. The substances most commonly employed for this purpose are salts of the black oxide of copper, particularly the sulphate and the acetate. The other substances employed as re- sists for indigo are sulphate of zinc, chloride of zinc, chloride of mercury (corrosive sublimate), and a mix- ture of corrosive sublimate and binarseniate of potash. None of these are in common use except sulphate of copper, acetate of copper, and sulphate of zinc. The ordinary course of operations practised in this style of work, with the view of producing merely a white pattern, are the following : The resist, mixed with unctuous matters and pro- perly thickened, is first printed on such parts of the cloth as are not to absorb the indigo, and the goods are suspended for one or two days (according to the composition of the resist) in a chamber at common temperatures, and not very dry. The pieces are then fixed on a frame and dipped into the indigo vat, which contains, in solution, the colourless hy- druret of indigo, or indigotin (see page 244). The solution of indigotin is immediately absorbed by the cloth on all parts where the resist had not been printed, which parts become deep blue when the cloth is afterwards exposed to the air, the soluble in- digotin passing into the state of insoluble indigo- blue through the absorption of oxygen. But wher- ever the resist had been applied, the solution of in- digotin is not absorbed by the cloth, partly on account of the unctuous matters contained in the resist, but chiefly from the action of the metallic salt on the CALICO-PRINTING PROCESSES. 401 indigotin in solution, by which either indigotin or else indigo-blue becomes precipitated before the solution reaches the interior of the fibre, and being precipitated, the indigo is rendered incapable of being absorbed by the pores of the cloth. The indigo-blue which is formed by the resist is merely attached to the sur- face of the cloth, and is easily removed by washing. The first chemical change which occurs when the cloth printed with a resist containing sulphate or acetate of copper or corrosive sublimate is dipped into the indigo- vat, is the decomposition of the me- tallic salt in the resist by the alkali or lime in the vat, whereby the cupreous salts afibrd a precipitate of hydrated protoxide of copper (black oxide) and corrosive sublimate, a precipitate of protoxide of mer- cury (red oxide).* These oxides are no sooner pro- duced than they exert an oxidizing action on the in- digotin in solution, and become reduced to the state of inferior oxides. The protoxide of copper becomes the red or suboxide (which generally requires to be cleared away at the end of the process by wincing the goods in dilute sulphuric acid), and the prot- oxide of mercury becomes the black oxide or sub- oxide. The mode of action of sulphate of zinc is some- what different. This salt exerts no oxidizing action on the indigotin, but causes the precipitation of that substance in an insoluble state by withdrawing the lime which holds it in solution. By the reaction of the lime in the solution on the sulphate of zinc, there are also precipitated sulphate of lime and oxide of * Commonly called the peroxide. 2 D 402 DYEING AND CALICO-PRINTING. zinc, both of wMch offer a meclianical impediment to the access of the liquid to the cloth. The sulphate of zinc resist should be used only in cases where it would not be allowable to expose the goods to dilute sulphuric acid, after having been dipped into the blue-vat, as if, for instance, a design had been previously applied in madder colours, this operation being unnecessary with the zinc salt. Cor- rosive sublimate is far too expensive, and also too weak, to be commonly employed as a resist for in- digo, except where a very delicate figure in madder colours has to be protected. The white pattern in the annexed specimen (No. 18) was produced by such a process as that just No. 18. described. For this style of work, the blue-vat or solution of indigotin may be made by mixing one hundred pounds of ground indigo, one hundred and thirty-five pounds of copperas, one hundred and seventy-five pounds of lime, and from sixteen hun- dred to two thousand gallons of water. The vat is fit for use two days after the materials are mixed. CALICO-PRINTING PROCESSES. 403 For a deep blue, the cloth is dipped into the vat for ten minutes and then exposed to the air for the same length of time, and the dipping and exposure to the air are repeated until the required depth of colour is obtained. The composition of the resist paste is varied ac- cording to the depth of colour in the blue ground. The following mixture is well adapted for dark blue : No. 1. 3 to 4 pounds of sulphate of copper, 7 pints of water, 5 pounds of pipe-clay, china-clay, or sulphate of lead, 4 ounces of soft soap, 3 pounds of gum. For a resist paste for light blue, the proportion of sulphate of copper may be reduced to eight ounces in a gallon of the paste. This resist we may call No. 2. The sulphate of zinc resist, for protecting a de- sign in madder colours as well as for preserving some white, may have the following composition : No. 3. 4 to 5 pounds of sulphate of zinc, 2 quarts of boiling water, 5| pounds of pipe-clay, 4 ounces of soft soap, 2 ounces of hog's lard, 2 quarts of gum Senegal water, containing six pounds of gum to a gallon of water. The sulphate of zinc is first dissolved in the hot water, and with this solution, while warm, the pipe- clay, soap, and lard are thoroughly incorporated. When the mixture is cold the gum-water is added. Such are the methods of obtaining a white figure on a blue ground by the resist style. To procure a 2 D 2 404 DYEING AND CALICO-PRINTING. design in white and light blue on a dark blue ground, the cloth is first printed with the strong cupre- ous resist (No. 1), dipped in the blue-vat and cleaned, as if a white design only is required. After being dried, it is printed with the weaker resist con- taining sulphate of copper (No. 2), again dipped in the blue-vat to a lighter shade, cleared in dilute sulphuric acid and dried. A great variety of coloured designs on the same ground may also be obtained by combining with the resist, either one of the saline solutions capable of im- parting a mineral colour, or else the mordant for a colouring matter to be applied by the madder style. A design composed of yellow figures on an indigo ground, is very commonly and easily obtained by combining* the resist with a salt of lead, and padding or wincing the cloth in a solution of bichromate of potash after being dipped into the indigo-vat and cleared. The successive operations to which a piece of calico is subjected in this kind of work are the following : 1. Printing with the mixture of resist and salt of lead, which may have the following composition : 1 gallon of water, 3 to 4 pounds of sulphate of copper, 1 pound of nitrate of lead, 1 pound of acetate of lead, 3 pints of a paste of precipitated sulphate of lead, 5 or 6 pounds of pipe-clay, 2 to 3 pounds of gum. 2. Hanging for one or two days in a room having a rather humid atmosphere ; 3. Dipping into the indigo- vat ; 4. Passing through dilute sulphuric acid; CALICO-PRINTING PROCESSES. 405 5. Steeping in water for half an hour, and wash- ing; 6. Wincing in a dilute solution of carbonate of soda; 7. Wincing in a solution of bichromate of pot- ash, containing five ounces of the bichromate per piece of calico ; 8. Wincing in dilute muriatic acid; 9. Washing in water. To obtain a figure of chrome-orange instead of chrome-yellow, the calico may be first treated as above, and afterwards winced in hot milk of lime to convert the chrome-yellow into chrome-orange. To procure a design in yellow and light blue on a dark blue ground, the cloth is submitted to the following operations : 1. It is first printed with the mixture of sulphate of copper and salts of lead for chrome-yellow, and on the parts to be light blue with a mixture of sul- phate of copper and acetate of copper, formed by mixing solutions of acetate of lead and sulphate of copper, allowing the mixture to settle and decanting the supernatant liquid ; 2. After being dried, the cloth is dipped into the blue-vat for the dark ground ; 3. It is next passed through dilute sulphuric acid to clear the whites of the suboxide of copper, and washed in water ; 4. After being winced in a mixed solution of car- bonate of soda and carbonate of ammonia, it is dipped a second time into the blue-vat for the light blue of the figure, and then washed in water ; 406 DYEING AND CALICO-PRINTING. 5. It is afterwards winced in a solution of bi- chromate of potash, and then drawn through a cistern containing a solution of one ounce of oxalic acid and one ounce of sulphuric acid to the gallon of water. A pattern comprising a figure of iron buff on a ground of indigo may be applied to cloth by a si- milar combination of the padding and resist styles, the cupreous resist being mixed with a salt of the peroxide of iron. After the ground of indigo is applied, the cloth is slightly washed, and then winced in a warm dilute solution of carbonate of soda to precipitate hydrated oxide of iron. A buff figure on a dark green ground is sometimes produced by first printing the cloth with the white resist No. 1 (page 403), then dipping into the blue-vat, and after the cloth is cleared and dried, padding it with buff-liquor and raising the buff by carbonate of soda. Another method of producing a coloured figure on the indigo ground is by combining with the resist paste a mordant for a vegetable colouring matter, to be applied by the madder style, after the cloth has been dipped into the indigo-vat. This kind of work, which is susceptible of a great variety of mo- difications, is distinguished as the lapis or lazulite style, from the resemblance of the calico thus printed and dyed to the mineral lapis lazuli. It is also known as the neutral style. To obtain a red figure on the indigo ground, the cloth is printed with a resist paste composed, essen- tially, of red liquor, sulphate of zinc, and acetate of copper. CALICO-PRINTING PROCESSES. 407 This resist may be made of the following materials, mixed in the order in which they are placed : No. 1. 2 gallons of boiling water, 6 pounds of alum, 4 pounds of crude acetate of lead, 4 ounces of chalk, added in small quantities at a time, and 6 ounces of sulphate of zinc. These materials having been thoroughly incorporated, the mixture is allowed to settle, and the clear su- pernatant liquid is decanted and mixed with acetate of copper and. gum Senegal, thus : No. 2. 1 gallon of the above clear liquid, 3 ounces of acetate of copper, 18 ounces of gum Senegal, 5 pounds of pipe-clay, 4 ounces of soft soap, and a little ground indigo for " sightening." One half of the liquid is well mixed with the acetate of copper, pipe-clay, and soap, and the gum Senegal is afterwards added, dissolved in the other half of the liquid. After being printed with this resist, the cloth is aged for two or three days, and then subjected to the following operations : 1. Drawing by rollers once* through the blue- vat at 70° Fahr., made from the proportions of lime, copperas, and indigo mentioned at page 402, but with only eight hundred gallons of water ; 2. Einsing in water ; 3. Dunging or branning; 4. Washing at the dash-wheel ; * If the cloth is exposed to the blue-vat for some length of time, the aluminous mordant is separated from the cloth by the lime in the vat. 408 DYEING AND CALICO-PRINTING. 5. Dyeing in the madder-beck, with from two to five pounds of madder per piece ; 6. Clearing by boiling first in bran-water and af- terwards in soap-water. To produce a light red figure with madder, the resist may have the following composition : 4 measures of the sulphate of zinc resist paste No. 3, page 403, 1 measure of the mixture of red liquor and sulphate of zinc made as above, 1 measure of weak peachwood liquor, 1 measure of water. For two reds the cloth may be printed with the preceding mixtures at the same time by the two- colour machine, and be treated afterwards in the manner just described. To obtain merely a small black figure on the indigo ground the cloth may be dipped in the blue- vat to the required shade, and then be printed with the mixture for producing a topical black dye, such as pernitrate of iron, copperas, and extract of log- wood (see page 360). But if the design includes figures in red and white, the black forming a more considerable portion of the figure than a mere out- line, it is better to mix iron liquor of 8° or 10° Twad. with the cupreous resist and to dye the cloth in the madder-beck, after having dipped it into the blue- vat to the proper shade. A great variety of pur- ple, lilac, and chocolate tints may also be obtained on the same ground, by combining with the cupre- ous resist, either weak iron liquor or else mixtures in various proportions of iron liquor with red liquor, and dyeing in madder after the dipping in the blue-vat. CALICO-PRINTING PROCESSES. 409 To impart to the blue ground a design in light blue, together with a colour capable of being applied by the madder style, the cloth may be treated as follows : 1. Print with the white resist No. 1 (page 403); 2. Dip into the blue-vat, wash, wince in dilute sulphuric acid, rinse in water and dry; 3. Print the mixture of the mordant with the cupreous resist on a part of the white figure pro- duced by the first resist ; 4. Dip a second time into the blue-vat, to obtain a light blue on the parts not protected by the second resist, rinse in water; 5. Dung, wash, and dye in the decoction of the dye-stuff, and afterwards clear by branning. If a white figure is required in addition to the above, the cloth is first printed with the strong white resist and dipped into the blue-vat as already described, and is afterwards printed on the protected parts, by the two-colour machine, if the design ad- mits, with the mixture of mordant and salt of cop- per, and also with a mild resist such as No. 2, page 403. It is then dipped into the blue-vat and dyed in the usual manner. To procure such a pattern as the annexed (No. 19), containing a design in orange, crimson, and white on a blue ground, the cloth is printed by the two-colour machine with the mixture of salts of cop- per and salts of lead (page 404) on the parts to be orange, and with a white resist on the parts to be crimson and white. After being dipped into the blue-vat and cleared in dilute sulphuric acid, it is winced in the following liquids: 1°, solution of car- 410 DYEING AND CALICO-PRINTING. No. 19. bonate of soda ; 2°, solution of bichromate of pot- ash ; and 3°, dilute muriatic acid. It is next passed through hot milk of lime to convert the chrome- yellow into chrome-orange, rinsed and dried, and is afterwards printed by block on parts of the white with the mixture for a topical or steam red or crim- son. The following specimen (No. 20), exhibiting a design in blue, yellow, green, red, and white on a dark chocolate ground, was produced by combining the lazulite style with a topical colour. This kind of work is distinguished as the " chocolate ground neutral style." For such a pattern the cloth is first printed (either by machine or block) with the white resist,* No. 1, page 403, on all the parts required to be yellow and white ; with the mixture of red liquor, * If a very small or well-defined white figure is required, the cupre- ous resist should be mixed with lime-juice and sulphuric acid or bi- sulphate of potash, to resist the mordant in the chocolate resist, after- wards applied as a blotch. Such a mixture is designated (not very ap- propriately) neutral paste. CALICO-PRINTING PROCESSES. 411 No. 20. sulphate of zinc, and acetate of copper, made as de- scribed at page 407, on the parts required to be red ; and with a mixture of iron liquor, red liquor, sul- phate of copper, and soft soap thickened with pipe- clay and gum, for the chocolate ground or " blotch." After having been aged for a day or two the cloth is drawn once through the indigo-vat, then washed, dunged, dyed in the madder-beck, and cleared by branning. Lastly, the mixture for a topical or steam yellow is applied by the block. A process referable to the resist style is that by which a white figure is obtained on a ground of ca- techu brown. On the parts to be preserved white, the cloth is printed with a solution of citrate of soda (such as that obtained by exactly neutralizing lime-juice with caustic soda) thickened with a mix- ture of pipe-clay and gum; or else, what is pre- ferred, a mixture of sulphate of zinc, pipe-clay, and gum. Such a resist may be printed on the cloth 412 DYEING AND CALICO-PRINTING. by one roller of a two or three colour machine, and the catechu mixture (page 361) by another roller, or if required, two or three shades of the brown may be applied by as many rollers. The action of both of these resist pastes is chiefly mechanical; but the sulphate of zinc also acts by precipitating the catechu in solution, and thus preventing its access to the fibre of the cloth. The same resist may be employed for preventing the deposition of catechu on a coloured design pre- viously applied iu madder colours. The specimen No. 8, page 361, is an example of such a combi- nation of the topical, madder, and resist styles. To produce this pattern, the cloth is treated as follows : 1. Print by the two-colour machine with strong red liquor for the red, and with a mixture of iron liquor with a little red liquor for the dark puce ; 2. Age, dung, and wash in the usual manner; 3. Dye in the madder-beck ; 4. Clear by branning, &c., and dry; 6. Cover all the figures thus produced, with a resist paste of sulphate of zinc, pipe-clay, and gum ; 6. Apply the catechu ground by a roughened roller, and age for a couple of days, previous to washing at the dash-wheel. A red shade may be given to the catechu ground by impregnating the entire surface of the cloth with weak red liquor, by a roughened roller, at the same time as the strong red and puce mordants are applied. Two shades of brown are sometimes imparted by ap- plying the weak red liquor to certain parts of the ground, as for instance in broad stripes, the inter- vening spaces having catechu only. CALICO-PRINTING PROCESSES. 413 5. DISCHARGE STYLE. The manner of producing a white or coloured pat- tern on a coloured ground by the topical application of a "discharger" to a cloth already mordanted or dyed is applicable to both mineral and vegetable colouring matters. Like the resist paste in the pre- ceding style, the discharger may act either on the colouring matter itself or on the mordant before the cloth is exposed to a dyeing liquid. Dischargers for mordants are generally acid mixtures quite similar to resists for mordants, but dischargers for colouring materials are obtained from different classes of che- mical substances according to the nature of the co- louring matter to be removed. The essential pro- perty required in a discharger is that of convert- ing the substances on the cloth into colourless or solu- ble products, which may be removed from the cloth so as not to interfere with the subsequent application of a colouring material to the parts discharged. 1. Dischargers for colouring matters. — The ma- terials used as dischargers for vegetable colouring principles are chlorine and chromic acid, the bleaching powers of which have before been alluded to (pages 238 and 239). To effect the topical discharge of a vegetable co- louring matter by means of chlorine, with the produc- tion of a white figure, the dyed cloth is printed on those parts which are to be discharged, with a thick- ened acid mixture, the composition of which is varied according to the fastness of the colour to be destroyed, 414 DYEING AND CALICO-PRINTING. and after being suspended to dry for a day or two, the cloth is drawn (by a pair of squeezing rollers) through a solution of chloride of lime not stronger than 8° Twaddell or 1-040. The calico should be extended on rollers while being drawn through the solution, and should not occupy more than two or three minutes in its passage. The solution of chlo- ride of lime is usually contained in a rectangular cistern of wood lined with lead, of the following dimensions ; six or eight feet long, three feet wide, and four or five feet deep. As soon as the goods are taken out of the solution of chloride of lime, they are put to soak in water ; after which they are washed either at the dash-wheel or in the rinsing machine, and then dried. The chemical reactions which take place in this process are by no means complicated. Chloride of lime does not of itself bleach Turkey red and some other fast colours immediately; so that a cloth dyed with such colours may remain for some minutes in contact with a solution of chloride of lime without any deterioration in colour. But the acid applied to certain parts of the cloth combines with the base of the chloride and liberates free chlorine, which exerts an instantaneous bleaching action on the vegetable colouring matter on those parts of the cloth. Almost the only colours to which chlorine can be thus applied as a discharger, are Turkey red and other madder colours and indigo, as the more delicate colours are easily discharged by chlo- ride of lime alone. A white discharger adapted for all madder colours except Turkey red may be made by dissolving four CALICO-PRINTING PROCESSES. 415 pounds of tartaric acid in a gallon of water, mixing this solution with a gallon of lime-juice of spec. grav. 44° or 48° Twad., and thickening the mixture with pipe-clay and gum. The white discharger for Turkey red requires to be somewhat stronger than the above. It may be made by mixing four pounds of tartaric acid with a gallon of lime-juice at about 30° Twad., and after thickening with pipe-clay and gum, adding about a pound of concentrated sulphuric acid, or two pounds of bisulphate of potash. In a particular style of work, the Turkey red is discharged by the direct topical application of chlo- rine, or rather of an aqueous solution of chlorine. It is in this way that the celebrated Bandana hand- kerchiefs, which have white figures on a dark ground, have been most successfully imitated by Messrs. Mon- teith of Glasgow. The style is only practised in the manufacture of handkerchiefs. From ten to fourteen pieces of cloth, previously dyed Turkey red, are stretched over each other quite parallel, and passed together by portions at a time (proceeding from one end of the pieces to the other end), between two leaden plates, one of which is su- perimposed immediately over the other. Each of these leaden plates is cut completely through so as to leave hollow places on all the parts required in white on the red ground. By means of a hydraulic press, the pieces of cloth are compressed between the leaden plates with a force of three hundred and twenty tons on the whole surface. While the cloth is exposed to this immense pressure, an aque- 416 DYEING AND CALICO-PRINTING. ous solution of chlorine (obtained hj adding sul- phuric acid to a solution of chloride of lime) is made to percolate downwards through the pieces by the openings in the leaden plates. As the compressed state of the cloth prevents the imbibition of the liquid except by the parts opposed to the design on the lead, the solution passes on in a circum- scribed channel to the lower leaden plate, where it escapes and is conveyed away by a waste-pipe. The portions of cloth through which the liquid passes are entirely deprived of their colour. As soon as the chlorine solution is passed through, water is made to percolate in a similar manner to wash away the chlorine, else the definition of the pattern would be impaired. The passage through the cloth of the chlorine solution and the water for washing is sometimes assisted by a pneumatic ap- paratus consisting of a large gasometer, from which a current of air is caused to proceed under a mo- derate pressure, and act in the direction of the liquid. When a considerable quantity of water has passed through the cloths, the pressure is removed and the pieces are washed and slightly bleached, whereby the lustre both of the design and ground is considerably increased.* After the production of a white figure on a co- loured ground by the application of the acid dis- charger and immersion in the solution of chloride of lime, coloured figures may be applied either to * A detailed account of this interesting process, by Dr. Ure, may be found in the Journal of the Royal Institution for 1823. CALICO-PRINTING PROCESSES. 417 the ground or to the white figure by grounding in topical colours by the hand-block. A common me- thod of imparting a coloured figure is by mixing with the acid discharger one of the two solutions ne- cessary for producing a mineral colouring material. For example, to impart a yellow figure to a piece of cotton dyed with Turkey red, such as the specimen No. 21, the cloth is treated in the following manner: No. 21. 1. It is printed by the machine with a chrome- yellow discharger composed of 1 gallon of lime-juice of spec. grav. 20° Twad., 5 pounds of tartaric acid, 4 pounds of nitrate of lead, with a mixture of Pipe-clay and gum as the thickener. 2. After hanging for a day or two, the piece is passed through the solution of chloride of lime at 8° Twad. 3. It is soaked in water and then slightly winced in water. 2 E 418 DYEING AND CALICO-PRINTING. 4. The piece is next winced for about a quarter of an hour in a solution of bichromate of potash containing from three to five pounds to the piece. 5. It is lastly passed through, or winced in, di- lute muriatic acid, washed at the dash-wheel and dried. To obtain both a white and a yellow figure on a Turkey red ground, the dyed cloth may be printed with two acid dischargers, one intended for the pro- duction of the white figure, the other for the yellow figure. The subsequent treatment of the cloth is the same as above. To impart a blue figure to the same ground, the dyed cloth is printed with a mixture of soluble Prus- sian blue, permuriate of tin, and tartaric acid, after which it is drawn through a solution of chloride of lime. The Turkey red thereby becomes discharged and the Prussian blue fixed on all the parts where the above mixture had been printed. The only substance besides chlorine which can be conveniently employed to effect the topical de- struction or removal of a vegetable colouring matter is chromic acid, which produces the decomposition of the colouring matter by virtue of its oxidizing power, the chromic acid becoming reduced to the state of green oxide of chromium. The vegetable colouring principle best adapted to this kind of work is indigo. To obtain a white pattern on an indigo ground by means of chromic acid, the cloth is first dyed uniformly with indigo in the ordinary manner, and then padded with a solution of bichromate of pot- CALICO-PRINTING PROCESSES. 419 ash containing about five or six ounces per piece. After being carefully dried in the shade at the or- dinary temperature, the cloth is next printed with a discharger containing tartaric acid, oxalic acid, citric acid, and sometimes muriatic acid; and im- mediately after the impression it is winced in water containing some chalk in suspension, then washed at the dash-wheel, passed through dilute sulphuric acid, and lastly washed in clean water. The colour of the indigo on the cloth is destroyed immediately on the application of the acid discharger : chromic acid is then liberated from the bichromate through the superior affinity of the acids in the paste for the potash, and the free chromic acid at once oxidizes and destroys the colouring matter. Indigo is almost the only substance which can be adapted to the chromic acid discharger, owing to the oxidizing action which the bichromate of itself exerts on vege- table colouring materials in general ; hence the reason also for drying the dyed goods, after being padded with the bichromate, in a darkened chamber and at the ordinary temperature. To produce a yellow instead of a white figure, the acid discharger may be mixed with a salt of lead: in other respects the process is the same as above. The following method of obtaining a white figure on a dark green ground is an example of the com- bination of the madder style of work with the chro- mic acid discharge style. 1. Dip the cloth in the blue- vat to the desired shade ; 2 E 2 420 DYEING AND CALICO-PRINTING. 2. Pad in a mixture of red liquor with bichro- mate of potash containing five or six ounces of the latter to the gallon, and dry in the shade ; 3. Print the cloth, without being washed, with a mixture of lime-juice, sulphuric acid, and oxalic acid ; 4. Pass the cloth through a mixture of hot water and chalk, and dye in a decoction of quercitron bark; 5. Wash and clear by branning. In this process, the mixture of lime-juice, sul- phuric acid, and oxalic acid, not only liberates chro- mic acid from the bichromate of potash, but also dissolves the subsulphate of alumina deposited from the red liquor: the parts on which this mixture is applied do not therefore become permanently dyed yellow when the cloth is exposed to the decoction of quercitron. The discharge style is applicable to cloths dyed with mineral as well as with vegetable and animal colouring matters. 1. A white figure may be produced on a ground of Prussian blue, by imprinting on the cloth a paste containing a caustic alkali (either potash or soda), and passing the cloth afterwards through a solution of oxalic acid. The Prussian blue is here decomposed by the action of the alkali, affording yellow prussiate of potash, or prussiate of soda, which may be removed by washing, and peroxide of iron, which is precipitated on the cloth, but is afterwards dissolved out by the oxalic acid. CALICO-PRINTING PROCESSES. 421 2. A white figure on a ground of manganese brown may be very readily obtained by imprinting the cloth, after being dyed brown in the ordinary manner (see page 390), with a slightly acid solution of proto- chloride of tin of a specific gravity about 70° or 80° Twad., or containing a pound and a half or two pounds of the protochloride per gallon, accord- ing to the intensity of the shade of the manganese ground. The solution of protochloride of tin is thickened with about a pound of starch to the gal- lon. The peroxide of manganese on the cloth is decomposed by the protochloride of tin and converted into protochloride of manganese, which being a very soluble salt is easily dissolved out by washing, leav- ing the parts white, or nearly so, on which the salt of tin had been applied. Peroxide of tin is formed at the same time, and remains for the most part at- tached to the cloth, but being white, it does not vitiate the pattern, and if required, may be made subservient to the application of the colouring prin- ciple of a vegetable dye-stufi", as peachwood, quer- citron, or logwood. As most acidulous mordants are capable of removing the peroxide of manganese and inserting their own bases instead, a great variety of coloured designs may be applied to the manganese ground by afterwards dyeing such goods in various dye-becks. To impart a design in white, blue, and yellow on the bronze ground (such as the specimen No. 15, page 390), the cloth on which the manganese has been raised may be printed with the salts of tin for the white ; with a mixture of berry liquor, alum, and 422 DYEING AND CALICO-PRINTING. salts of tin for the yellow; and with a mixture of salts of tin, prussiate of potash, pernitrate of iron, muriatic acid and British gum, for the blue spots. The colour of the latter mixture is at first greenish- white, hut it changes to blue on exposure to the air. A design in different shades of red and pink may- be communicated to the same ground by means of a mixture of peachwood liquor or cochineal liquor with alum, perchloride of tin, and protochloride of tin, thickened with gum tragacanth; and a mixture of logwood liquor, with alum and the two chlorides of tin, thickened with starch, may be used for im- parting different shades of purple and violet to the same ground. A figure in chrome-yellow may be produced on a ground of manganese bronze by printing on the dyed cloth a discharging material composed of tartaric acid, nitrate of lead, and salts of tin. After the cloth is dried, it is passed, first, through lime-water, then through a solution of bichromate of potash, and af- terwards through dilute muriatic acid to brighten the yellow. 3. Protochloride of tin, when mixed with sul- phuric and tartaric or oxalic acid, is also used as the discharging material for chrome-yellow and chrome-orange. The discharge of the chromates of lead is effected, in this case, by the reduction of the chromic acid to the state of green oxide of chromium, which forms soluble salts with the acids. A variety of coloured designs may also be applied by combining with the discharger, the materials for CALICO-PRINTING PROCESSES. 423 the production of a topical colour. Thus, a blue figure is sometimes produced by printing on the orange or yellow cloth a mixtui^e of the two chlorides of tin, Prussian blue, and muriatic acid; a violet figure, by logwood liquor mixed with alum, tartaric acid, protochloride of tin and starch; and a red or pink figure, by a similar mixture containing peach- wood liquor instead of logwood liquor. Another material which may be used for dis- charging chrome-yellow and chrome-orange, with a view of producing a white figure, is a strong caustic alkaline solution, but protochloride of tin will ge- nerally be found more convenient and more effec- tive. 4. A white figure on a ground of iron buff (page 388) is obtained by applying to the coloured cloth a mixture of tartaric and oxalic acids with lime-juice, thickened with pipe-clay or China-clay and gum. The acids dissolve the peroxide of iron, and the figure is obtained perfectly white by wash- ing. The readiest way of discharging the iron is to apply the acid mixture after the cloth has been padded in the iron liquor, and before it is exposed to the alkaline solution to precipitate the peroxide. A solution of protochloride of tin in a dilute acid, thickened with starch, is also sometimes used as a white discharger for iron buff; and for producing coloured designs, the protochloride may be mixed with perchloride of tin and either logwood liquor, peachwood liquor, or berry liquor. The following method of producing white and buff-coloured figures on a dark green groun'd is an 424 DYEING AND CALICO-PRINTING. example of the combination of such a process as the above with the resist style. 1. The cloth is printed with the white resist for the indigo-vat (No. 2, page 403); 2. It is dipped into the blue-vat, rinsed, and dried; 3. It is padded with rather weak iron liquor and aged; 4. A solution of tartaric and oxalic acids in lime- juice, thickened with pipe-clay and gum, is applied by the block to parts of the buff spots ; 5. The cloth is washed in water holding chalk in suspension to remove the acid paste ; 6. It is lastly winced in an alkaline solution, to raise the buff, and then washed. The white figure is here produced by the discharge of the salt of iron from parts of the spots on which the indigo had been resisted ; the buff figure is the remainder of those spots, and the dark green ground results from the mixture of the indigo with the buff. 2. Dischargers for mordants. — Another method of producing white or coloured figures on a co- loured ground, referable to the discharge style of work, is by the removal of the mordant previous to the application of the colouring material. This method is particularly adapted to grounds of mad- der and logwood with an iron or aluminous mordant. The material used for the discharge of the mordant is usually a mixture of tartaric acid, oxalic acid, and lime-juice, the proportions of the constituents being varied according to the strength of the mordant to be discharged. The following mixture may be CALICO-PRINTING PROCESSES. 425 used for discharging the mordant from a piece of cloth impregnated with red liquor of . spec. grav. 7° Twad. or weaker, or with iron liquor of spec. grav. 2° Twad. or weaker : 1 gallon of lime-juice of spec. grav. 6° Twad., 3^ ounces of oxalic acid, and 4 ounces of tartaric acid, Thickened with pipe-clay and gum if for application by the block, or with British gum if by the roller. Sometimes the proportion of tartaric and oxalic acids and the strength of the lime-juice are considerably- reduced, and hisulphate of potash, oil of vitriol, and cream of tartar are introduced instead. The ordinary operations practised on calico in this style of work to obtain a white figure are the fol- lowing : 1. The cloth is padded or printed with the solu- tion of the mordant for the ground, and is imme- diately dried by being drawn either through the hot- flue or over steam boxes ; 2. After a moderate ageing, the calico, without being washed, is imprinted by the roller with the discharging paste, which immediately dissolves the subsalt formed during the ageing; 3. The calico is next suspended for a day or two in a cool place, not very dry, and if the mordant is peroxide of iron, it is then passed through water heated to about 130° Fahr. and rendered slightly alkaline by the addition of a small quantity of car- bonate of soda;* * The passing of the cloth through a dilute solution of carbonate of soda is sometimes omitted, particularly when alumina is the mordant, in which case a quantity of chalk is added to the dung-beck to neutralize the free acid in the discharger. mam 426 DYEING AND CALICO-PRINTING. 4. The cloth is afterwards washed, dunged, and dyed in the vegetable infusion; after which it is cleared by soaping or branning and wincing in so- lution of chloride of lime in the usual manner. Wherever the acid paste had been applied, the co- louring material does not attach itself, in consequence of the removal of the mordant from those parts. It will be observed that this kind of discharge work is very similar to the resist style, in which an acid paste is first imprinted on the cloth to prevent the attachment of a mordant subsequently applied to the whole surface of the cloth (see page 395); the only difference between the two styles consist- ing in the order of applying the acid and the mor- dant. The best whites are no doubt generally procured by the resist style; as it is easier for an acid to prevent the attachment of a mordant in an insoluble form, than to dissolve it, when once pre- cipitated. To procure a white design on a black ground, such as the annexed specimen (No. 22), by the discharge No. 22. CALICO-PRINTING PROCESSES. 427 of the mordant, the cloth may be treated in the following manner : 1. Pad or print the calico with a mixture of equal measures of iron liquor of spec. grav. 6° Twad., and red liquor of 8° Twad., thickened with starch or British gum; 2. Dry over the steam boxes, age, and apply a discharger composed of tartaric acid, sulphuric acid, and lime-juice, thickened with British gum ; 3. Pass the cloth through warm water mixed with chalk ; 4. Dye in decoction of logwood, mixed with a little bran and dung ; 5. Wash, clear the white by branning, rinse and dry. The following method of producing white and blue figures on a purple or chocolate ground presents an example of the combination of such a style as the above with the indigo resist style : 1. The white calico is padded with red liquor; 2. After the cloth has been aged for a short time, the thickened acid discharger is applied by the cylinder to all the parts intended to be blue or white ; 3. After hanging for twenty-four hours, the calico is dunged, dyed in the madder-beck, and cleared by branning ; 4. On the parts of the white spots which are in- tended to remain white, the sulphate of zinc resist for the indigo-vat, such as the mixture described at page 403, is imprinted; 5. After the cloth is dried, it is dipped into the 428 DrEING AND CALICO-PRINTING. blue-vat and exposed to the air ; then washed at the dash-wheel, and dried. The white figure is here produced through the discharge of the aluminous mordant by the acid, and by the action of the sulphate of zinc resist on the indigo : the blue figure is produced by the indigo on the white spots to which the resist was not ap- plied, and the purple or chocolate ground results from the mixture of the indigo with the madder red.* A discharger for one mordant is sometimes mixed with the solution of another mordant on which it exerts no action, so that the mordant in the dis- charger becomes attached to the cloth, on the spots from which the previous mordant is removed. Thus, subacetate of iron may be separated from a piece of calico, and alumina imparted in its place, by applying to the mordanted cloth a mixture of red liquor with protochloride of tin. In this manner, a red figure on a violet or lilac ground is some- times produced, the cloth being first covered with weak iron liquor, then dried, printed with the mix- ture of red liquor and protochloride of tin, dunged, * A simpler and better method of obtaining the same effect is by tlie " chocolate ground neutral style," the principle of which is described at page 410. The cloth is first printed with the white cupreous resist (mixed with a free acid, when a very well defined figure is required), and afterwards with the chocolate resist (page 411) for the ground, the parts required in blue being left white. The cloth is then aged, drawn once through the blue-vat, washed, dunged, dyed with madder, and cleared by branning. This interesting style of work is very little prac- tised at present, it being superseded by the cheaper but much less per- manent steam blue and steam sapan chocolate, of which a specimen is introduced at page 374. CALICO-PRINTING PROCESSES. 429 dyed in the madder-beck, and cleared in the usual manner. To obtain a white figure as well as the red, the mordanted cloth should be also printed with lemon-juice, or with a mixture of lemon-juice and sulphuric acid. The use of a mixture of protochloride of tin and red liquor as a red resist for iron liquor, with the view of producing the same effect, has before been adverted to (pp. 397, 398). One of these two pro- cesses is almost always followed whenever a figure in madder red is required on a ground of madder purple or black. In a few ingenious processes related to this kind of work, for producing coloured figures on coloured grounds, an acid solution of protochloride of tin is applied as a kind of discharger to a cloth dyed uni- formly with peachwood, quercitron or madder, by means of an iron mordant. By mutual decomposition, the protochloride of tin in the discharger and the peroxide of iron on the cloth give rise to chloride of iron and peroxide of tin, or rather, the oxide of tin intermediate be- tween the protoxide and peroxide. The chloride of iron, being soluble, is removed by washing, but the insoluble oxide of tin remains attached to the fibre, and combines with the colouring principle previ- ously united to the oxide of iron. This double de- composition of oxide of iron and protochloride of tin may be made subservient to the production of a red figure on a black ground. For this purpose the cloth is first covered with iron liquor, then dyed to a black in decoction of peachwood, and af- 430 DYEING AND CALICO-PRINTING. terwards printed with the acid solution of the pro- tochloride. Wherever the salt of tin is applied, the colour of the cloth changes from black to red, through the transference of the colouring principle of the peachwood from oxide of iron to oxide of tin. In a similar manner, a red figure may be obtained on a ground of madder purple or lilac, and by sub- stituting quercitron for madder or peachwood, a yel- low figure is produced on a drab ground. The iron liquor employed in these processes should not be stronger than 3° or 4° Twad. 6. CHINA BLUE STYLE. The style of calico-printing by which the China blue prints are produced is an interesting modifica- tion of the topical style. These prints are distin- guished by having blue figures, usually of two or three different depths of colour, associated with white, as the specimen No. 23. To produce such a pattern, the bleached calico is subjected to the following operations. It is first printed, either by the block or cylinder, with a mix- ture of indigo, orpiment (sulphuret of arsenic), sul- phate of iron or iron liquor, gum or starch, and water; the proportions of gum or starch and water being varied according to the depth of colour required. After being printed, the calico is suspended in a dry atmosphere for a day or two, and stretched in per- pendicular folds on a rectangular wooden frame, sus- pended by pulleys and a rope from the ceiling of the apartment. The frame with the cloth is then dipped CALICO-PRINTING PROCESSES. 431 No. 23. in a certain order into the three following liquids: No. 1, milk of lime; No. 2, solution of copperas; No. 3, solution of caustic soda. These liquids are contained in three adjacent stone cisterns, the tops of which are on a level with the ground : the usual dimensions of the cisterns are, eight or nine feet in length, four feet in depth, and three feet in width. Into the vats No. 1 and No. 2, the calico is dipped several times alternately, with exposure to the air for a short time between each dip ; it is not dipped so frequently into the vat No. 3, and the dipping in this always immediately follows No. 2. By these operations, the insoluble indigo-blue applied to the surface of the cloth becomes converted into indigotin which is dissolved and transferred to the interior of the fibres, where it is precipitated in the original in- soluble form. The chemical changes which take place in these successive operations are rather complicated, but ad- mit, nevertheless, of a satisfactory explanation. By 432 DYEING AND CALICO-PRINTING. the successive immersions in milk of lime and so- lution of sulphate of iron, protoxide of iron comes to be precipitated on the surface of the cloth. This protoxide of iron, with the assistance of the lime, re- acts on the indigo imprinted on the calico, convert- ing it, through the intervention of water, into in- digotin, which dissolves in the lime-water, and the solution is absorbed into the pores of the cloth. On exposure to the air, the indigotin absorbs oxy- gen, and insoluble indigo-blue is deposited within the fibre in a fixed state. The protoxide of iron produced in the subsequent alternate immersions into the sulphate of iron vat and into the lime-vat, acts only on the indigo which still remains on the surface of the calico, not having free access to the indigo within the fibre; and as the alternate dippings are continued (up to a certain number), so the propor- tion of indigo on the surface diminishes, and that of the indigo within the fibre increases. The orpiment contained in the pigment printed on the cloth seems to act chiefly by increasing the density of the mixture, thus preventing its ready disintegration and removal by the various liquids to which the cloth is exposed. It also assists, probably, in deoxidizing the indigo-blue in conjunction with the lime. By these operations the whole surface of the cloth becomes impregnated with a considerable quantity of oxide of iron, to remove which, the cloth is plunged (being still on the frame) into a fourth similar cistern containing sulphuric acid of about the spec. grav. 5° Twad. (1-025.) It is afterwards washed in clean water, and then again brightened in dilute sulphuric CALICO-PRINTING PROCESSES. 433 acid. Lastly, the clearing of the white ground is sometimes completed by exposing the cloth to warm soap-water. The following method of preparing the China blue mixture of different shades is described by M. Thil- laye, in his useful work on calico-printing.* The materials employed are, 15| pounds of indigo, in coarse powder, 3| pounds of orpiment, 22 pounds of copperas, and 9 5 gallons of water, or water and gum-water. The indigo, orpiment, copperas, and four gallons and a half of the water are well ground together in a mill for three days ; the mass is then removed, and the mill is washed with a gallon of water which is added to the mixture. The remaining four gallons of water are afterwards added ; but if a very thick blue is required, as much strong gum-water is intro- duced instead. From this mixture, which may be called No. 1, several' lighter shades are procured by diluting it with water or gum-water in the following order : Quantity by Quantity by measure measure of No. of No. I. water or gum-water. 1 1 mixed with 0 2 11 „ 1 3 10 „ 2 4 8 „ 4 5 6 „ 6 6 4 „ 8 7 2 „ 10 8 2 „ 12 9 2 „ 14 10 2 „ 16 11 2 „ 18 12 2 „ 20 * Manuel du fabricant d' Indiennes, Paris, 1834. 2 E DYEING AND CALICO-PRINTING. To produce a small single blue figure, the mixture No. 5, thickened with starch, may be applied by ' the block, and No. 4, thickened with gum, by the roller. For two different blues, applied by the block, there may be used, 1°, the mixture No. 4, thickened with starch ; and 2°, No. 9, thickened with gum. For three different blues, applied by the block, there may be taken, 1°, the mixture No. 5, thickened with starch; 2°, No. 7, thickened with starch; and 3°, No. 10, thickened with gum. The mixture described by M. Thillaye is not ex- actly the same as that commonly employed in this country. Instead of copperas, the Lancashire prin- ters generally use iron liquor, and British gum instead of common gum; they also take little more than half as much orpiment as is directed in the receipt of M. Thillaye. The following proportions of the ma- terials will probably be found to form a convenient mixture: 16 pounds of ground indigo, 5 or 6 gallons of strong iron liquor, 2 pounds of orpiment, and British gum and water sufficient to make 8 gallons. When required for use, this mixture, which con- tains two pounds of indigo to the gallon, may be diluted with water or gum-water in the order fol- lowing : CALICO-PRINTING PROCESSES. 435 Quantity of indigo Quantity by measure Quantity by measure in one gallon oj No. of above mixture. (f water or gum-water. the mixture. lbs. oz. 1 1 0 2 0 2 1 k 1 51 3 1 I 1 31 4 1 1 1 0 5 1 2 0 lOf 6 1 3 0 8 7 1 5 0 51 8 1 7 0 4 9 1 9 0 3^ 10 1 12 0 21 11 1 16 0 11 The darkest of the two shades of blue in the spe- cimen of this style of printing (page 431) was pro- duced from a mixture containing one pound of indigo to the gallon (as No. 4), and the lighter from a mixture containing three ounces of indigo to the gal- lon (No. 9). Both were thickened with two pounds of British gum per gallon, and were applied at once by the two-colour machine. The milk of lime for dipping China blue prints may be prepared by mixing two hundred pounds of lime with a thousand gallons of water. When in constant use, the lime- vat requires to be replenished twice daily, both with lime and water. The strength of the solution of copperas is varied from 3i° Twad. (1-017) to 6° Twad. (1-030), it being regulated more by the quantity of the figure in the pattern than by the depth of colour required. The kind of copperas generally preferred for this purpose is that technically known as " green cop- peras," which contains a small quantity of free sul- 2 f 2 436 DYEING AND CALICO-PRINTING. phuric acid. The superiority of this variety of cop- peras merely consists in the comparative slowness with which it becomes peroxidized or " rusty" by exposure to the air. The copperas-vat does not re- quire replenishing quite so frequently as the lime-vat, and the cistern need not be emptied for six months or longer. The bottom and sides of the cistern be- come lined with a dense crystalline deposit of oxide of iron and sulphate of lime, as hard as the cistern itself. The strength of the solution of caustic soda may vary from 6° to 9^ Twaddell (1-030 to 1-045). It is made in the usual manner by carbonate of soda and quick-lime. * The order of dipping the frame into the three cisterns is as follows : 1. Dip in the first vat (lime) for ten minutes. Drain for five minutes. 2. Dip in the second vat (copperas) for ten minutes. Drain for five minutes. 3. Dip in the first vat for ten minutes. Drain for five minutes. 4. Dip in the second vat for ten minutes. Drain for five minutes. 5. Dip in the third vat (soda) for ten minutes. Drain for five minutes. 6. Dip in the second vat for ten minutes. Drain for five minutes. 7. Dip in the first vat for ten minutes. Drain for five minutes. 8. Dip in the second vat for ten minutes. Drain for five minutes. PRINTING or FABRICS OF SILK AND WOOL. 437 9. Dip in the first vat for ten minutes. Drain for five minutes. 10. Dip in the second vat for ten minutes. Drain for five minutes. 11. Dip in the third vat for ten minutes. Drain for five minutes. The addition of a small quantity of nitrate of lead to the China blue mixture, when iron liquor and not copperas is used, is said to impart considerable viva- city to the colour ; but I am not aware of its being usual to make this addition, unless with a view of producing a green instead of a blue design, when the cloth, after having been dipped as above and cleared in dilute sulphuric acid, is winced in a solution of bichromate of potash in order to produce chrome- yellow. This is by no means an advantageous pro- cess for obtaining a green figure in the China blue style, as the lime and soda vats are apt to become so. highly charged with oxide of lead as to deposit that oxide on the white parts, which consequently be- come yellow when the cloth is exposed to the bi- chromate. A better method is to add red liquor and perchloride of tin to the China blue mixture, and to dip in the three vats in the usual manner; after which the cloth is cleared in very dilute sulphuric acid, dyed in decoction of quercitron mixed with size, cleared by branning, and lastly, winced in a dilute solution of alum to brighten the green. Printing of mousselin de laines, silks, chalis, &c. — The fixation of colouring matters on fabrics of 438 DYEING AND CALICO-PEINTING. silk and wool is commonly effected by the process of steaming. No mineral colouring material, with the exception of Prussian blue, is applied to these tissues ; nor is it usual to impart to them colouring matters from infusions of vegetable or animal productions by the madder style, except in a few difficult processes of silk printing. These fabrics were formerly printed entirely by the block, but latterly the roller and the press-machine (page 341) have been substituted. The colour mixtures for de laines, which are formed of cotton and wool, should be of such a na- ture as to afford an uniform deposit of colouring mat- ter on both the animal and vegetable fibre. These mixtures are sometimes composed of two distinct bases, one capable of attaching itself firmly to the wool, the other to the cotton. Thus, a preparation sometimes used for imparting a blue colour to de laines, is a mixture of the steam blue for cotton (see page 374) with indigo-paste or soluble blue (sulph- indigotate of potash) for the wool. In a particular kind of fancy dyeing, the woollen thread only is dyed, and the cotton is afterwards perfectly bleached by exposing the dyed de laines to a dilute solution of bleaching powder. The cotton thread is sometimes dyed of another colour, either before or after the dye- ing of the woollen thread. Before being printed, de laines are always impregnated with peroxide of tin, from two different solutions applied consecutively as already described (see page 261). The steaming of the printed de laines, which is performed either by the column or chamber, usually lasts about three- quarters of an hour; but the time varies according PRINTING OF FABRICS OF SILK AND WOOL. 439 to the quantity of acid in the mixtures, and to the manner in which the steam is applied. With a con- siderable quantity of acid, the fibres become weakened if the process is prolonged, and a shorter time is re- quired with the column than with the chamber. In general, the only difference between the com- position of the mixtures for steam colours for wooUen goods and those for cotton goods (page 368) is that the former contain more free acid than the latter, or that the colouring matter is held in solution more strongly in the former than in the latter. Whether the mordant is perchloride of tin, protochloride of tin, or alum, a considerable quantity of tartaric or oxalic acid is almost always introduced. The most vivid colours are generally obtained by protochloride of tin, with either oxalic or tartaric acid. The brilliant steam blue distinguished when on woollen goods as " royal blue," is formed through the decomposition of hydroferrocyanic acid, as before explained. The composition of the mixture printed on the cloth is much the same as the steam blue for cotton (page 374), but is more concentrated, and perchloride of tin is introduced instead of alum. The solution of yellow prussiate of potash, which should contain not less than three pounds of the prussiate in a gallon, is mixed with sufficient tartaric acid to precipitate the whole of its potash as bitartrate of potash (cream of tartar), which may be separated and employed in the preparation of tartaric acid. The best mixture for a steam scarlet for woollen goods, is made of cochineal liquor, gall liquor, pro- tochloride of tin, and oxalic acid. It may be thick- 440 DYEING AND CALICO-PRINTING. ened with gum, if for blotches or grounds; and with starch, if for small figures. The best mordant for producing different shades of yellow with berry liquor is a mixture of alum and red liquor; and with decoc- tion of quercitron bark, a mixture of red liquor and oxalic acid, or else alum alone. The only preliminary operations to which silken cloth intended to be printed, is commonly subjected, are, 1% boiling in a solution of soap and carbonate of soda to remove the "gum;" 2°, passing through dilute sulphuric acid; aiid 3°, washing and drying. Some printers recommend the steeping of the silk in a solution of alum, after it is taken out of sulphuric acid, but this is by no means a common practice. The processes for printing and dyeing silks according to the madder style, are very similar to those for cottons: the thickened mordant is first applied; the piece is then dried, aged for a couple of days, winced in bran-water, dyed in the hot vegetable decoction, and cleared by being winced in boiling bran-water! In some styles of work, the silk is afterwards soaped* impregnated with a solution of tin, and, lastly, passed through very dilute sulphuric acid. The madder style of printing and dyeing is rather difficult of execution on silken cloth, and is conse- quently not much practised on this variety of textile fabrics. The common method of ornamenting silk with different coloured designs is by means of steam colours, a great variety of which may be imparted, of sufficient fixity to bear all ordinary exposure to deteriorating influences. With the exception of the preliminary operations previous to the application of PRINTING OF FABRICS OF SILK AND WOOL. 441 the colour-mixture, the treatment of silks in this style of work is the same as that of cottons. A remarkable style of printing and dyeing is largely practised on silken and woollen goods, which possesses not the smallest resemblance to any one of the varied processes to which cotton goods are subjected. This is the mandarining style^ by which a yellow or orange colour may be communi- cated to the silk or wool by exposing the stuff to the action of nitric acid. The colour proceeds from a peculiar substance formed through the decomposition by the acid of a portion of the fibre of the cloth itself. On the parts intended to be preserved white, the con- tact of the acid with the cloth is prevented by the application of a resist paste composed of resin and suet. Taking, in the first place, the simplest illustration of this style of work, that is, the production of a white design on an orange ground, the operations practised on the cloth are the following. The silk, having been first cleaned from its resin- ous coating in the usual manner, is printed on the parts which are to remain white with the fatty resist of resin and suet. A quantity of this mixture is kept in a melted state near at hand, and a portion is occasionally laid over a piece of woollen cloth stretched on a frame which forms the top of a copper chest. Steam is admitted into the chest by a pipe in order to preserve the resist in a liquid state. When the silk is ready to receive the resist, the printer heats his block, takes up some of the resist from the frame, and applies it immediately to the silk 442 DYEING AND CALICO-PRINTING. by a light blow with a mallet. The block is instantly removed, to prevent it from adhering to the silk. When the printing of the whole piece is completed, the silk is passed through dilute nitric acid, obtained by adding from one to two parts of water to one part of aquafortis of commerce; the acid is heated as high as possible without endangering the solidity of the resist paste, the melting of which would evi- dently be attended with serious inconveniences. The silk should not remain in the acid longer than one minute. The nitric acid is contained in a sand-stone or an earthenware trough, which is placed within a copper or wooden box to serve as a water-bath: the heat applied is that of steam. A reel is placed on each side of the trough to guide the silk as it enters and leaves the acid. On being withdrawn from the acid, the silk is im- mediately washed in a stream of cold water; after which, the resist is cleared away, and the orange brightened by wincing the silk in boiling soap-water to which a little soda is added. The piece is lastly washed in cold and hot water successively, and dried. Such is the method of obtaining a white figure on an orange ground. Coloured figures are obtained in this style of work by a variety of ingenious and elegant processes, applicable, like that just described, to chalis as well as silks. One or two examples will suffice as illustrations. White and blue figures on an orange ground may be procured in the following manner. The piece is first printed with the resinous resist, to preserve the parts which are to remain white from contact with PRINTING OF FABRICS OF SILK AND WOOL. 443 the acid. It is next dyed blue in the indigo-vat in the ordinary manner, washed and dried, and the resist is then printed on those parts which are to remain blue. The next process is the mandarin- ing or passing through the nitric acid; by which the indigo is destroyed on all parts of the cloth except where the resist is applied, the cloth thus acquiring a ground of orange. The piece is lastly washed, and the orange brightened by a boil in soap- water with a little alkali. An orange ground having been applied to the cloth by such a process as the preceding, the colour of the ground may be afterwards modified or com- pletely altered by dipping the cloth in some dyeing liquid, the figures being still protected, if necessary, by the resinous resist. For example, a design in white and blue figures on a green ground may be im- parted to a chali by simply dipping the piece, after having been treated as above for blue and white figures on an orange ground, in the blue-vat, pre- vious to the removal of the resinous resist from the blue and white figures. White, blue, and orange figures on a green ground may be obtained by im- printing the resinous resist on the silk or chali after the mandarining process, and before the second immersion in the blue-vat. An orange figure on a blue ground is sometimes produced by printing the nitric acid thickened with British gum upon the cloth previously dyed in the blue-vat. The piece is afterwards exposed to the action of steam, and is lastly boiled in soap-water to brighten the orange. 444 DYEING AND CALICO-PRINTING. Superficial as the preceding account of calico- printing processes may and must appear to those who are acquainted, both practically and theoreti- cally, with all the details of this beautiful art, it will probably be found sufficiently minute and exact to substantiate the claim of calico-printing to be considered not only one of the most important, but the most ingenious and refined of all the chemical arts. From the great variety of processes and of materials employed, almost every principle in the- oretical chemistry receives an application or illustra- tion in some one or other of the operations of the calico-printer. It has thus happened that several interesting discoveries in theoretical chemistry, made in the experimental laboratory, have actually been anticipated by the printer, from observations made in the print-works and dye-house. INDEX. Acetate of iron, see Iron liquor. „ of alumina, see Red liquor. Acids, action of, on compounds of colouring matters and mordants, 295. Adrianople red, see Turkey red. Affinity, chemical, 7. Ageing of cottons printed with alumi- nate of potash, 285. „ printed with red liquor, 284. „ printed with iron liquor, 292. Albumen, compound of, with corrosive sublimate, 186. „ muriate of, 186, wofe. „ vegetable, contained in wood, 164, 183. „ vegetable, how removed from wood, 185. Albuminate of mercury, 186, note. Alburnum, 156. Alizarine, 252. Alkanet, 247. Alterants, 270. Alum, 276. „ basic, 278. „ proximate and ultimate consti- tuents of, 28. „ test for the purity of, 277. „ use of, for preserving wood, 190. „ use of, in purifying coal-gas, 89. Alumnia, ;icetate of, see Red liquor. „ how applied to cloth, 276. » how prepared, 276, noie. „ nitrate of, 286. „ subsulphate of, 278. « tartrate of, 286. Aluminate of potash, 285. » action of muriate of am- monia on, 286. '» effects of ageing cottons printed with, 285. « of soda, 286. Aluminum, chloride of, 286. Ammonia in coal-gas, 88, Ammoniacal liquor of gas-works, 36 ; composition and uses of, 92. Annatto, 247. „ how applied to tissues, 244. „ when introduced into Europe, 224. Antimony orange, 233, 254. Apophyllite, formula for, 32. Aqua-fortis, 17. Archil, 224, 248. Argand burner. 111. Arseniate of chromium, 255. Arsenious acid, use of, for preserving wood, 192, 199. Ash from wood, 172, 173, 174. Assistant mordant, 294. Arsenite of copper, 256. Avignon berries, 250. B. Bandanna handkerchiefs, 415. Barwood, 248. Bases, 1 1, note. Basic alum, 278. Bat- wing burner, 110. Bergmann, researches of, in dyeing, 232. BerthoUet, introduction of chlorine by, 232. „ researches of, in d3'eing, 232. Berries, Persian, French or Avignon, 250. Bichromate of potash, use of, for pre- serving wood, 196. Bitumen, use of, for preserving wood, 196. Black, steam, 370. „ resist, for the blue-vat, 409. „ topical, 260. Bleaching of cotton, 259. „ of mousselin de laines, 260. Block, hand printing, 333. Blue, Prussian, 256. „ steam, 374, 439. „ topical, 365. 446 INDEX. Blue-vat, 402. Bone-size, 308. Boracic acid, 12. Boucherie's mode of impregnating wood witli a liquid, 201. Bran, use of, in clearing dyed goods, 321. Branning, 312, 321. Brazil-wood, 224, 248. British gum, 345. Brown, resist for catechu, 411. „ topical, 361. Bude light, 112, note. Burnett, patent of Sir William, for preserving wood, &c., 197. C. Calendering, 325. Calico-printing, derivation of the name of, 226. „ history of, 222, 228. „ processes in, 331. „ progress of, in England, 229. Camiium, 155. Camwood, 248. Carbonate of lime, 14. Carburetted hydrogen, 54. Catechu, 249. „ resist for, 411. Cellulose, 1 68. Charcoal, animal, decolorizing power of, 240. Chemical affinity, 7, 12. „ combinations, definite nature of, 1 3 ; direct and indirect, 21. China blue style, 430. China blue, mixture for, 422, 424. ,, order of dipping for, 426. China clay, use of, as a thickener, 346. Chloride of calcium, use of, in purifying coal-gas, 90. „ of copper, use of, for preserv- ing wood, 195. „ of lime, use of, in clearing dyed goods, 321. „ ofmercurv,use of, in preserv- ing wood, 185, 187, 199. „ of zinc, use of, for preserving wood, 197. Chlorine, action of, on vegetable colour- ing matters, 238. „ how applied in calico-printing as a discharger, 413, e< seq. „ relative affinity of di^ferent metals for, 1 1 . Chocolate, spirit, 364. Chocolate ground neutral style, 410, 428, note. Chromates of potash, use of, for pre- serving wood, 196. Chrome-orange, 386, 405. „ dischargers for, 422. Chrome-yellow, 255, 385, 404. „ dischargers for, 422. „ mode of applying a design in, to a Turkey red ground, 417. Chromic acid, use of, for discharging indigo, 418. „ action of, on vegetable colouring matters, 239. Chromium, arseniate of, 255. Cleansing liquor of print-works, 308. Clearing excess of colouring matter by bran, 321, 350. ,, excess of colouring matter by chloride of lime, 322, 350. „ excess of colouring matter by soap, 322, 350. Clegg's dry gas-meter, 142. Coal, composition of, 47 ; how ascer- tained, ib. „ impurities in, 49. „ products of the destructive distil- lation of, 65, 79. ,, secondary products of the distil- lation of, 92. „ value of the products of the distil- lation of, 121. Coal-gas retort, 66. Coal-gas, advantage of using dry coal in making, 87. „ ammonia in, 88. „ comparison of the illuminat- ing power of, with that of oil-gas, 126. „ composition of, at different stages of the process, 81. „ cost of, compared with that of other sources of light, 123, 124. „ density of, compared with its illuminating power, 131. „ disadvantages of too high a temperature in making, 83. „ how freed from ammonia, 89, 90. „ lime purifier for, 72. „ mode of burning, as a source of heat, 115. „ modes of estimating value of, 126. „ outline of process for making, 35. „ present consumption of, in London, 45. INDEX. 447 Coal-gas, process for the complete ana- lysis of, 136. „ process of making, 62, 82. „ product of, from different kinds of coal, 85. „ production of, at different gas-works, 125. „ state of the manufacture of, in London in 1 823, 44 ; and at the present time, 45. Coal-naphtha, composition and uses of, 94, 95. Coal-oil. 94. Coal-tar, 36, 94, 95, 148. Coccinellin, 249. Cochineal, 249. „ dyeing cottons with, 358. Cockspur flame, 110. Coke, 95 ; uses of, 96. Colour doctor, 337. „ nature of, 245. Colouring matters, attachment of, to tissues, 242. „ dischargers for, 413. „ form compounds of different colours with different mordants, 2/4. „ general composition of vegetable, 233. „ general properties of vegetable, 233. „ how imparted to wood, 213. „ list of vegetable and animal, 247. „ mineral, how applied to cloth, 263, 383. „ mostly derived from vegetables, 233. „ organic, division of, 243. „ organic, how applied to tissues, 243. „ resists for, 399. M vegetable, action of chromic acid on, 239. n vegetable, action of chlorine on, 238. 5, vegetable, action of sulphurous acid on, 239. „ vegetable, colourless bases of, 240. •5 vegetable, combina- tions of, with alumina, &c., 236. Colouring matters, vegetable, unite che- mically with bases, 237. Combining proportions, 15. Condenser for coal-gas, 7 0, Cooler for coal-gas, 70. Copper, arsenite of, 256. „ prussiate of, 256. „ use of chloride of, for preserv- ing wood, 195. „ use of oxide of, for preserving wood, 195, „ use of salts of, for resisting indigo, 400. „ use of the sulphate of, for pre- serving wood, 189. Copperas, use of, in purifying coal-gas, 89. Corrosive sublimate, use of, in preserv- ing wood, 185, 199, 218. Cotton, bleaching of, 259. Cow-dung, composition of, 305. Creosote, use of, for preserving wood, 193. Cudbear, 248, Cylinder printing, 336. „ capabilities of, 231. „ invention of, 231. Cylinder printing machine for pencil- blue, 367. D. Dash- wheel, 319. Davy lamp, 59. Decay of wood, 151; causes of the, 175, 182. „ a process of oxidation, 175. Decoctions for dyeing, how made, 317. Decompositions, double, 23. De laines, bleaching of, 260. „ printing of, 438. Dextrin, 345 ; produced from lignin, 166. Discharge, chlorine, 413, 414. Discharge of indigo by chromic acid, 418. „ style, 413. „ style, principle of, 332. Discharger and mordant combined, 428. „ for colouring matters, 413. „ for iron buff, 423. „ for manganese brown, white and coloured, 421. „ for Prussian blue, 420, Dischargers for chrome-yellow and chrome-orange, 422. „ for mordants, 424. Doctor, colour, and lint, 337. Drying machine, steam, 325. 448 INDEX. Dry gas meter, 142. Dry-lime purifier for coal-gas, 75. Dry-rot, 152. Dung, action of, in the dunging pro- cess, 306. „ composition of, from the cow, 305. Dung substitute, 307 ; how best applied to cloth, 309. Dunging process, how performed, 303. Dunging sometimes superseded by branning, 312. „ use of, in calico-printing and dyeing, 303. Duramen, 156. Dye-beck, 313. „ how heated, 316. Dyeing, history of, 222. „ materials used by Romans in, 223. „ objects of, 221. „ operation of, 313, 316. „ processes of, different for diiFer- ent kinds of tissues, 257. „ processes of, general nature of, 257, 262. „ purity of water used in, 327. Dyers' spirits, 287. E. Elements, 7. Endogens, structure of, 158. * Epsom salts, or sulphate of magnesia, 27. Equivalents, chemical, 15, 18. „ tables of chemical, 16 and 34. Etching of printing rollers, 339. Eudiometer, lire's, 132. Eupion, 194. Exogenous trees, growth of, 154. „ structure of stem of, 154, F. Fancy colours, 363, note. Fat resists, 393. Felspar, 9, 32. Femambouc wood, 248. Fibre, affinity of the animal and vege- table, for colouring matters, 242. Fire-damp, 58. Fish-tail burner, 111. Flame, cause of the luminosity of, 108. Flame, structure of, 104, 106. Flour, 344. French berries, 250. Furnace, singeing, 257. Fustet, 250. Fustic, 250. G. Galls, 253. Gas cooler, 70. „ flames, chimneys for, 113, 114. „ illumination, 35 ; see Coal-gas. „ „ economy of, 121. „ „ history of the pro- gress of, 37. „ lights, ventilation of, 117. ,, meters, 141. „ meter, Clegg's dry, 1 42. „ moderator, Platow's, 140. ,, regulators, 138. Gas, mode of burning, 104. „ naphthalized, 145. Gas-works, arrangement of, 63, 64. Gasometer, 76 ; telescope gasometer, 78. Garancine, 252, 351. Glazing of cottons, 325. Granite, 9. Green, steam, 379. Gum arabic, 345. „ Senegal, 345. „ tragacanth, 346. Gum, British, 345. Gypsum in coal, 51. H. Humus from oak, composition of, 177. Hydraulic main, 68. Hydriodic acid, composition of, 14. Hydrocarbons, 52. Hydrochloric acid, composition of, 14. Hydroferrocyanic acid, 376. Hyett, experiments of Mr. W. H., on the impregnation of wood, 204, 218. I. Ignition, 104. Indigo, 251. Indigo-vat, 402. Indigo, as a topical colour, 366. ,, how applied to tissues, 244. „ how discharged by chromic acid, 418. „ peculiar action of chlorine on, 2 38. INDEX. 449 Indigo, use of, formerly prohibited, 225, „ resist style with, 400. „ when introduced into Europe, 224. Indigotin, 251. Iron buff, 256, 388, 406. „ „ discharger for, 423. „ liquor, how prepared, 292. „ „ resists for, 395, 397, 399. „ „ use of, as a mordant, 291. „ use of, for preserving wood, 198,199,218. „ mordants, 291. „ pyrites in coal, 50, 51. Iron, acetate of, see Iron liquor. „ aceto-persulphate of, 293. „ pernitrate of, 292. „ peroxide of, 256. „ pyrolignite of, see Iron liquor. „ „ use of, for preserving wood, 198, 199,218. „ sub-pernitrate of, 293. „ sub-persulphate of, 293. „ test for the presence of, 277. Isomerism, 53. K. Kermes grains, 251 . Kyan's process for protecting wood, 187. L. Lac dye, 251. Lakes, 236. Lamp, ventilating, 119. ,, safety, 59. Lamp-black, composition of, 170, note. Lapis style, 406. Lazulite style, 406. Lead, chromate of, 255. „ use of sulphate of, in purifying coal-gas, 91. Light carburetted hydrogen, 54. Light, constitution of, 245. Light-gas, see Coal-gas, Gas illumi- nation. „ density of, compared with the illuminating power, 131. „ process for the complete ana- lysis of, 136. „ modes of estimating the va- lue of, 126. Lignin, 165. Lignin-sulphuric acid, 167. Lime, affinity of, for tissues, 243, note. Lime, experiment on, as a preservative for wood, 190. „ purifier for coal-gas, 72. Lint doctor, 337. Liquor, patent purple, 294. ,, iron, see Iron liqiior. „ red, see Red liquor. Litmus, 248. Logwood, 251. „ dyeing cottons with, 358. „ when introduced into Europe, 234. „ use of, prohibited by Queen Elizabeth, 224. Lowe's naphthalized gas, 145. M. Macquer, M., researches of, in dye- ing, 232. Madder, 252. „ colours, application of fat re- sist to, 394. ,, „ combination of, with mineral and steam colours, 392. „ combination of, with steam colours, 382, 394. „ purples, 353. ,, „ and reds conjoined, 353, 429. „ reds, 354. ,, style of printing, principle of, 331. „ „ of printing, processes in, 347, et seq. „ style, combination of, with the discharge style, 419, 426. Madder, use of adding sumach to, 351, note. Mandarining style, 441. Manganese brown, 255, 390. „ „ white and coloured dischargers for, 421. Manganese, use of sulphate and chlo- ride of, in purifying coal-gas, 91. Matters, colouring, see Colouring matters. Medullary processes, 154, 155. Mercer, Mr., introduction of antimony orange by, 233. „ introduction of manganese bronze by, 233. Mercury, albuminate of, 186, note. Meters for gas, 141. 2 G 450 INDEX. Mica, 9. Mineral colouring matters, combination of, withmadderand steam colours, 392. „ „ how commonly ap- plied to cloth, 263. „ „ modes of applying, 383. Mordant, 266. Mordant and discharger combined, 428. „ assistant, 294. Mordants, aluminous, 276. „ dischargers for, 424. „ how appUed, 267, 272. „ iron, 291, „ resists for, 395. „ tin, 287. Mouldered wood, composition of, 177, 179. Mousselin de laines, bleaching of, 260. „ „ printing of, 438. " Mule " printing machine, 232. Murdoch, Mr., introduction of coal-gas by, 41, 42, Muriate of ammonia in coal, 50. N, defiant gas, 56, Orange, antimony, 254. Orpiment, 255. Oxide of copper, preservatioa of wood by, 195. Naphthalin, 59, Naphthalized gas, 145, Neutral style, 406. Nicaragua wood, 248. Nitrate of alumina, 286. Nitrates of iron, 292, 293. Nitric oxide, 17. „ acid, 17. Nitrous acid, 17. „ oxide, 17. 0. Oak-wood, composition of humus from, 177. Oil of wood-tar, preparation of, 194, „ ,, use of, for preserving wood, 193, 194, Oils, vegetable and animal, use of, for preserving wood, 191, Oil-gas, 97. „ apparatus for making, 98. ,, comparison of the illuminating power of, with that of coal- gas, 126, „ liquids obtained by compression of, 100, „ properties and composition of, 99, P. Padding style, 332. Pallampoors, 228. Paranaphthalin, 61. Parrot coal, 51, Pastes, resist, for indigo, 403, Peach-wood, 248. Pencil blue, 366. Perchloride of tin, 287, Pernitrate of iron, 292, Peroxide of iron, 256, ,, of nitrogen, 17. „ of tin, how applied to cloth, 287, 288, „ „ preservation of wood by, 195. „ „ use of, as a mordant, 287. Perrotine, 335. Persian berries, 250. Phlogiston, theory of, 4. Photometer, Ritchie's, 128. Pink salt, 289, Pink, spirit, 364. Pipe-clay, use of, as a thickener, 346. Pitch, 94, Plato w's gas moderator, 140. Plum spirits, 290, Potash, aluminate of, 285, „ stannate of, 289, „ use of chromates of, for preserv- ing wood, 196, Preservation of wood, 151, „ „ by alum, 190. „ „ byarseniousacid, 19-2, 199, „ „ by bitumen, 1 96, „ „ by chloride of zinc, 197. ,, „ by the chromates of potash, 196, „ „ by common salt, 190, „ „ by corrosive sub- limate, 1 85, 187. „ „ by creosote, 193. ,, „ by iron liquor, 198, 199, „ „ by oil of wood- tar, 194. INDEX, 451 Preservation of wood by oxide of cop- per, 19.5. „ „ by peroxide of tin, 19,5, „ „ by a resinous coating, 188, „ „ by solution of creosote, 195. „ „ by sulphate and acetate of cop- per, 189, „ „ by sulphate of iron, 189, 199. „ „ by sulphate of zinc, 189. „ by tannin, 192. „ „ by vegetable and animal oils, 191. „ „ by wood - tar, 193. Preservative materials for wood, 184, 188. Preserving wood, Kyan's process for, 187. Press printing, 340. Printing by roller, 336. „ „ invention of, 231. „ roller, how made, 338. Protochloride of tin, 290 ; use of, as a resist for iron liquor, 397- Protosulphate of iron, use of, in puri- fying coal-gas, 89. Protoxide of tin, use of, as a mordant, 289. Proximate constituents, 27. Prussian blue, 256, 374, 384, „ as a topical colour, 365. „ how discharged by an alkali, 420. „ how applied to wood, 213, 214. „ how applied as a steam- colour. 374. „ mode of applj'ing a de- sign in, to a Turkey red ground, 418. Prussiate of copper, 256. Purple liquor, patent, 294. Purple, madder, 353. „ spirit, 363. „ steam, 371. „ Tyrian, 222 ; durability of, 22 3. Pyrolignite of iron, see Iron liquor. Q- Quartz, 9. Quercitron, 253. „ dyeing cottons with, 357. R. Rainbow style, mode of printing for the, 334. Rays of light, coloured, 245. Red liquor, altered by heat, 283. „ constitution of, 283. „ effects of ageing on cottons printed with, 284. „ preparation of, 280, 282. ,, resist for, 395. Red resist for the blue- vat, 407. „ Sanders wood, 253. „ spirits of dyers, 287. Red, steam, 371. Resin, covering of, for wood, 188. „ products of the distillation of, 103. Resin-gas, 101. „ „ apparatus for making, 102. Resist black for the blue-vat, 408. „ pastes for indigo, 403. „ purple and chocolate, for the blue-vat, 409. „ red, for the blue-vat, 407. „ for catechu brown, 411. „ style, principle of the, 332, „ „ processes in the, 393. Resists for colouring matters, 399. „ for indigo, 399. „ for mordants, 395, Resists, adaptation of, to the madder style of work, 394, 396. „ fat, 393, Retort, Clegg's rotary, 83, „ coal-gas, 66, Regenerator, Malam's gas, 148, Regulators, 138. Rinsing machine, 320, Ritchie's photometer, 128, Roller printing, 336. capabilities of, 231. invention of, 231. Rotary retort, 83. Royal blue, 439. S, Safety lamp, 59, Safflower, 253, ,, how applied to tissues, 244, Sago starch, 345, Salep, 346, 452 INDEX. Salt, common, in coal, 50. „ „ use of, for preserving wood, 190. „ composition of, 13, 19. „ general meaning of the term, 1 1 . Salts of tin, 290. Sandal wood, 253. Sapan wood, 248. Saw-wort, 253. Scheele's green, 256, 392. Seasoning of wood, 159 ; Langton's mode of, 160. Sightening of mordants, 346. Silk, how prepared for printing, 261. „ printing of, 440. Singeing, 257. Soap, use of, in clearing dyed goods, 321. Soda, aluminate of, 286. „ citrate of, use of, as a resist, 399. Solution, 24. Soot, composition of, from wood, 170, note. Spirit chocolate, 364. „ colours, 363, note. „ pink, 364. „ purple, 363. „ yellow, 365. Spirits, dyers', 287. Spurious coal, 51. Squeezing-rollers, 323. Stannate of potash, 289 ; application of, to cotton for steam colours, 369. Starch contained in wood, 165. „ sugar, 167. Starch, wheat, 344. Starching machine, 324. Station meter, 1 45. Steam black, 370. „ blue, 374. ,, „ for woollen goods, 439. „ colours, 368, 381. „ „ for woollen goods, 439. „ combination of, with madder colours, 382, 394. „ ,, combination of, with madder and mineral colours, 392. „ „ adaptation of, to resist style and madder style, 394. n „ preparation of cotton for receiving, 369. „ drying machine, 325. „ green, 379. „ printing, principle of, 332. „ purple, 371. „ red, 371. Steam scarlet for woollen goods, 439. „ yellow, 372. Steaming process, 379. Stereotype printing-plate, 335. Stick-lac, 251. Substitute liquor, 309. Substitute, dung, 307. Substitutions, double and single, 23, 24. Sulphate of copper, use of, for preserv- ing wood, 189. ,, ,, use of, for resisting indigo, 400. „ of iron, use of, for preserving wood, 189, 199. „ of lead, use of, as a thickener, 346. „ ,, use of, in purifying coal-gas, 91. „ of magnesia, 27, 29. „ of zinc, iise of, for preserving wood, 189. Sulphuretted hydrogen, composition of, 14. Sulphuric acid, use of, in purifying coal- gas, 90. „ relative affinity of dif- ferent bases for, 1 1. Sulphurous acid, action of, on vegetable colouring matters, 239. Sumach, 253. Surface printing, 232, 342. Swallow-tail burner. 111. Symbols, 29 ; table of, for elements, 30. T. Tannin, use of, for preserving wood, 192. Telescope gasometer, 78. Temperature, change of, a result of che- mical action, 20. Terra Japonica, 249. Thickeners used in calico-printing, 343. Tin mordants, 287. Tin, peroxide of, use of, as a mordant, 287. „ protoxide of, use of, as a mordant, 289. „ use of perchloride of, for preserving wood, 195. „ use of protochloride of, as a resist for iron liquor, 397. Tissues, affinity of lime for, 243, note. Topical and steam colours, 359. „ black, 260. „ blue, 365. „ brown, 361. „ style of printing, principle of, 332. INDEX. 453 Tragacanth, gum, 346. Turf-gas, 104. Turkey red, history of, 22.5. „ mode of applying a design in Prussian blue to a ground of, 418. „ mode of producing a chrome-yellow design on a ground of, 417. „ white discharge for, 415. Turmeric, 254. Turnsole, 248. Tyrian purple, 222 ; durability of, 223. U. Ultimate constituents, 27. Union-jet flame, 110. " Union " printing machine, 232. Ure's eudiometer, 132. V. Valonia, 253. Vegetable albumen, 1 64. „ how removed from wood, 185. „ how to ascertain proportion of in wood, 183. Vegeto-sulphuric acid, 176. W. Wash-off colours, 363, note. Water, composition of, 14. Water extracter, 323. „ used in dyeing, 327. Weld, 254. Wheat starch, 344. Winsor, Mr., introduction of coal-gas into the metropolis by, 43. Woad, 254. Wood, amount of water in, 161. „ ash, 172. „ Boucherie's mode of impregnat- ing, with a liquid, 201. ,, composition of mouldered, 177, 179. „ decay of, 151, 175, 182. „ density of, 1 62, 1 63, 1 64, 21 6. Wood, effects of the impregnation of, with foreign substances, 206. „ how freed from albumen, 185. ,, how to apply colours to, 213. ,, how to ascertain proportion of vegetable albumen in, 183. „ how to increase or diminish strength of, 211. „ how to preserve flexibility and elasticity of, 207. „ how to reduce the inflammabi- lity and combustibility of, 212. „ Kj'an's process for preserving, 187. „ necessary condition for the de- cay of, 181. „ preservation of, 151, see Preser- vation of wood. „ preservative materials for, 184, 188. „ products of distillation of, 169. „ properties and composition of, 153. „ starch contained in, 165. „ smoke from, 170. „ tar of, products of distillation of, 194. „ „ use of, for preserving wood, 193. Woody fibre, composition of, 168. „ tissue, function of, 153. „ „ origin of, 158, tiote. „ ,, structure of, 154. Woollen goods, printing of, 437. „ steam colours for, 439. Y. Yellow fustic, 250. „ lake, 236. Yellow, steam, 372. „ spirit, 365. Z. Zinc, use of chloride of, for preserving wood, 197. Zinc, use of sulphate of, for preserving wood, 189; for resisting indigo. LONDON: Printed by S. & J. Bentley, Wilson, and Fley, Bangor House, Shoe Lane. 38 98335(1- TP, flttfiEnvctitit, USiURr