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 N.C. STATE UNIVERS1T 
 
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THIS BOOK MUST NOT BE TAKEN 
 FROM THE LIBRARY BUILDING. 
 
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Digitized by the Internet Archive 
 
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DYEING AND CALICO PRINTING. 
 
MANCHESTER : 
 PALMER AND HOWE, PRINTERS, I, 3, AND 5, BOND STREET. 
 
1 1 
 
s&^r 
 
DYEING AND CALICO PRINTING: 
 
 INCLUDING AN ACCOUNT OF THE MOST RECENT 
 IMPROVEMENTS IN THE 
 
 Manufacture and Use of Aniline Colours. 
 
 Illustrated with Wood Engravings and numerous Specimens 
 of Printed and Dyed Fabrics. 
 
 BY THE LATE 
 
 DR. F. CRACE-CALVERT, F.R.S., ECS., 
 
 CORRESPONDING MEMBER OF THE ROYAL ACADEMY OF TURIN, OF THE 
 MEDICAL SOCIETY OF BRUSSELS, THE INDUSTRIAL SOCIETY OF 
 MULHOUSE, HONORARY MEMBER OF THE PHARMACEU- 
 TICAL SOCIETIES OF LONDON, AND PARIS, ETC. 
 
 EDITED BY 
 
 JOHN STENHOUSE, LL.D., F.R.S., &c, 
 
 AND 
 
 CHARLES EDWARD GROVES, 
 
 Fellow of the Chemical Societies of London and Berlin. 
 
 THIRD EDITION 
 
 MANCHESTER: 
 
 PALMER AND HOWE, 73, 75, & 77, PRINCESS STREET. 
 
 LONDON : SIMPKIN, MARSHALL, & CO. 
 
 1878. 
 
 The right of translation is reserved. 
 
PREFACE. 
 
 "PHIS work, for the most part, consists of the 
 revised MSS. of a treatise on colours other 
 than aniline, on which the late Professor Crace- 
 Calvert was engaged almost up to the time of his 
 decease. The rapid strides which Chemical Science 
 is now making, however, rendered numerous addi- 
 tions and corrections necessary so as to bring it, as 
 far as possible, up to the present time; and, although 
 the author did not contemplate treating of the 
 Aniline Colours, yet from the great interest of the 
 subject, both in its Theoretical and Technical 
 aspect, it has been thought advisable to add a brief 
 account of the most recent discoveries which have 
 been made in this very important branch of the 
 Colour Industry. 
 
 In a book like the present it would, of course, be 
 impossible either to give a complete scientific account 
 of the different chemical products connected with 
 the various dyestuffs, or to enter into all the techni- 
 cal details of the Art of Dyeing and Calico Printing; 
 the object of the late Professor Crace-Calvert being 
 to present his readers with a general and compre- 
 hensive view of these important and interesting 
 subjects. ^ _. _ _ 
 
 95990 
 
vl. PREFACE. 
 
 In the alterations which we have made in* the 
 original MSS., and in the additions that have been 
 found necessary, it has ever been our object to 
 mould the work into the form in which, had he sur- 
 vived, the author himself would have wished to see 
 it produced. 
 
 In conclusion, we have to thank those firms who 
 have been kind enough to supply the Dyed and 
 Printed Specimens with which to illustrate the work, 
 viz., Messrs. Walter Crum and Co., Messrs. E. Potter 
 and Co., Messrs. Salis Schwabe and Co., Messrs. 
 Steiner and Co., Messrs. Symonds, Cunliffe, and Co., 
 and Messrs. Wood and W T right, all of Manchester; 
 Messrs. Heys and Co., of Barrhead, near Glasgow; 
 Messrs. Marnas and Co., Lyons ; Messrs. Dollfus, 
 Mieg, and Co. ; Mons. Gustave Schaeffer, of the firm 
 Messrs. Haeffely and Co., Chateau de Pfastadt, near 
 Mulhouse, who has given the specimens of coal-tar 
 colours on woollen, and especially to Mons. Horace 
 Koechlin, of Wesserling, Alsace, to whose courtesy 
 and kindness we are indebted not only for the series 
 of beautiful aniline colours printed on cotton, and 
 for the new dyes Fluorescein, Coerulein, and Eosin, 
 but also for several valuable epistolary communi- 
 cations. 
 
 (Signed) 
 
 John Stenhouse, 
 Charles Edward Groves. 
 
OBITUARY 
 
OBITUARY 
 
 OF THE LATE 
 
 DR. FREDERICK CRACE-CALVERT, F.R.S. 
 
 Dr. Frederick Crace-Calvert, F.R.S., was born near London on 
 the 14th of November, 181 9. 
 
 In the year 1835, when 16 years of age, he left London and 
 went to France, where he commenced the study of chemistry 
 under the celebrated chemist Gerardin, at Rouen, and continued 
 with him for two years. At the expiration of this time he went to 
 Paris, and carried on his studies at the Jardin des Plantes, the 
 Sorbonne, College de France, and Ecole de Me'decine, his atten- 
 tion being principally given to the Natural Sciences. 
 
 About the age of 21 he was appointed to manage the well 
 known works of Messrs. Robiquet & Pelletier, where the manu- 
 facture of pure chemicals and pharmaceutical products is carried 
 on. This position, however, he soon vacated on being offered 
 that of " Demonstrates de Chimie Applique'e," under the eminent 
 chemist Chevreul, and here he remained from 1841 till 1846, 
 when he left France. From the former date his career as a 
 chemist began ; and was continued with untiring energy during the 
 succeeding 32 years. 
 
 He published his first paper, "Sur l'extraction de quinine et 
 cinchonine," in September, 1841. 
 
 In 1843, in conjunction with M. Ferrand, he elaborated an 
 interesting paper on the analysis of gases enclosed in some organs 
 
x. OBITUAR Y. 
 
 of plants, the gases being taken from the same plants at different 
 times of the day and year in order to demonstrate the action of the 
 sun's rays. This paper is entitled " Memoir sur la Ve'ge'tation," and 
 may be found in Volume V. of "The Comptes Rendus." In the 
 following year the diseases of beer engaged his attention, and 
 some interesting facts were embodied by him in a paper read to 
 the Socie'te de Pharmacie, "Sur la fermentation visqueuse de la 
 biere." 
 
 From 1843 unt il tne ^ me of his leaving France he was engaged 
 in a research on some compounds of lead which first brought him 
 into note. One of the papers consequent on this may be found 
 in the "Comptes Rendus'* of 1843, entitled "Proce'de au moyen 
 duquel on obtient un protoxyde de plomb cristallise et ayant la 
 couleur du minium." 
 
 In 1844, he wrote "On the presence of Indigo in the Orchi- 
 daceous plants;" in 1846, "On the preparation of Calomel on 
 the large scale;" and, in the same year, a compilation of facts 
 relating to the properties of animal black. 
 
 On returning to England, at the latter end of 1846, he was first 
 appointed to the chair of the honorary professorship of chemistry 
 at the Royal Institution, and afterwards to that of lecturer on 
 chemistry at the School of Medicine in Pine Street, Manchester. 
 
 In 1847, he published a paper "On Bleaching Powders," and, 
 in 1848, one "On the Bleaching of Cotton and Flax." 
 
 About this time Dr. Calvert gave a long series of lectures on 
 his favourite subject, at the Athenaeum, Manchester, viz., "The 
 Application of Chemistry to Manufactures." These w r ere recorded 
 in the daily papers. 
 
 During the following years many other subjects engaged his at- 
 tention, but we may notice the following publications as some of 
 the results of his labours. 
 
 In 1849 " Process for the Preparation of Chlorates, particularly 
 the Chlorate of Potash." 
 
 In 185 1 "On the Oxides and Nitrates of Lead." 
 
 In 1854 "A case of Poisoning by the Sulphate of the 
 Protoxide of Iron." 
 
 In 1855 "On the Adulteration of Tobacco."— "On the Action 
 
OBITUAR Y. xi. 
 
 of Organic Acids on Cotton and Flax Fibres."— "On the Actions 
 of Gallic and Tannic Acids in Dyeing and Tanning." 
 
 In 1856 "On the Solubility of Sulphate of Baryta in different 
 Acids." — "On the Purification of Polluted Streams." 
 
 About this time he commenced an enquiry, in conjunction with 
 Mr. Richard Johnson, on the physical and chemical properties of 
 different alloys. The publications resulting from these investiga- 
 tions were : 
 
 In 1858 "On the Hardness of Metals and Alloys." — "On the 
 Conductibility of Metals and Alloys." — "On the Chemical Changes 
 which Pig Iron undergoes in its Conversion into Wrought Iron." 
 
 In 1 86 1 a series of papers "On the Expansion of Metals and 
 Alloys." 
 
 In 1862 "On the Composition of a Carbonaceous Substance 
 existing in Grey Cast Iron." — " On the Employment of Galvanised 
 Iron for Armour Plated Ships." — "On the Conductibility of Heat 
 by Amalgams." 
 
 In 1863 "On the Preservation of Iron Plated and other Ships." 
 
 The interest he took in the preservation of ships from the action 
 of sea water never ceased; many unrecorded experiments were 
 carried on by him at intervals on this subject till the last days of 
 his life. 
 
 In 1865 Mr. Richard Johnson and he published "On the 
 Action of Sea Water on certain Metals and Alloys," and in 1866 
 "On the Action of Acids on Metals and Alloys." 
 
 In 1870, two papers appeared by Dr. Calvert, one "On the 
 Composition of Iron Rust," the other "On the Oxidation of 
 Iron," and a third on the same subject in 187 1. 
 
 In 1858 we find a publication of his "On a New Method of 
 preparing Hydrochloric Acid." 
 
 In 1859 "On the Analyses of Wheaten Flours." — "Influence 
 of Science on the Arts of Calico Printing." — "On Starches: the 
 purposes to which they are applied, and improvements in their 
 Manufacture." 
 
 During this year, his attention was called by his friend the late 
 Dr. Ransome to hospital gangrene, and in seeking its cause he was 
 led to investigate the compounds produced during putrefaction. 
 
xii. OBITUAR Y. 
 
 Two papers, descriptive of his results, appeared in i860, the 
 first "On Products of Putrefaction." The second "On New 
 Volatile Alkaloids given off during Putrefaction." He continued, 
 these researches during the following two or three years, and 
 had collected about an ounce of a precipitate, produced by com- 
 bining the gaseous products of putrefaction with platinum, by 
 passing the gases emitted by the putrefying meat through bichloride 
 of platinum, by means of aspirators, during many months. This 
 accumulation of precipitate was unfortunately destroyed before its 
 examination could be completed, through the carelessness of one 
 of his assistants, which caused him much regret ever afterwards. 
 
 In 1 86 1 he wrote "On Improvements in the Manufacture of 
 Colouring Matters," and "On the Chemical Composition of Steel." 
 A report followed " On the Action of Water supplied by the 
 Manchester Corporation on Lead of different kinds," in connection 
 with the Manchester Sanitary Association. 
 
 In 1862 he gave a series of lectures to the Society of Arts, 
 " On the Improvements and Progress in Dyeing and Calico Print- 
 ing since 1851;" in 1864 "On Chemistry as applied to the Arts;" 
 in 1866 "On Discoveries in Agricultural Chemistry," and "On 
 Discoveries in the Chemistry of Rocks and Minerals." 
 
 These were the beginning of the Cantor lectures, which are 
 now continued every year by different lecturers. 
 
 In this same year we find another paper by him, "On Wood 
 for Shipbuilding." 
 
 In 1863 he patented and worked out his process for the separa- 
 tion of sulphur from coke, by the use of common salt, for the 
 purpose of the manufacture of iron of superior quality. 
 
 The following is a list of some of his other publications : 
 
 In 1865 "On the Action of Silicate and Carbonate of Soda 
 upon Cotton Fibres." — "On the Crystallised Hydrate of Phenic 
 Alcohol." 
 
 In 1866 "On the Hydraulicity of Magnesian Limestone." 
 "On the preparation of Acetylene." 
 
 About this time he interested himself with the properties of 
 phenic or carbolic acid, and being satisfied of its valuable disin- 
 fecting properties, built works for its manufacture, and to him 
 
OBITUAR Y. xiii. 
 
 belongs the honour of being the first to manufacture it in this 
 country in a pure state; and through his exertions it has been in- 
 troduced as a valuable therapeutic agent. 
 
 In 1867 he wrote papers "On Oxidation by means of Char- 
 coal." — "On the Presence of Soluble Phosphates in Cotton Fibres, 
 Wheat, and other Seeds," and five articles "On the Synthesis of 
 Organic Substances." 
 
 In 1867 "Carbolic or Phenic Acid and its Properties" (three 
 articles). 
 
 In 1869 "Presence of Soluble Phosphates in Seeds." — "Pre- 
 paration of Nitrogen." 
 
 In 1870 "Testing Petroleum." 
 
 In 1872 "Sulphur in Coal and Coke;" and papers on "Pro- 
 toplasmic Life;" "Vitality of Disease Germs," &c, which received 
 much attention on the continent. 
 
 In 1873 he gave his last course of lectures in connection 
 with his colleague the late Dr. Turner, at the Royal Institution, 
 which were confined to physiology and the chemistry of the same, 
 and in which both aimed to show that religion and science could 
 go hand in hand, and neither produce injurious results on the 
 other. 
 
 In concluding the list of Dr. Crace-Calvert's various researches 
 we may mention that, besides the above, many others were made 
 by him, but their unfinished state does not justify publication. 
 Among these may be mentioned one on "Light," which cost him 
 much labour, and one "On the Action of different Gases on each 
 other under Enormous Pressures." 
 
 He was a Fellow of the Royal Society, of the Chemical Society, 
 Member of Royal Academy of Turin, Member of Royal Academy 
 of Medicine of Brussels, and of many other societies both at 
 home and abroad. 
 
 Dr. Calvert showed remarkable devotion to the science he 
 studied, and his knowledge of its literature was such as very few 
 have attained, and such also as could only be obtained by a most 
 unusual amount of reading, accompanied with strong interest, and 
 in all probability much pleasure. He showed this knowledge 
 more in the departments referring, to industry, and, as might be 
 
xiv. OBITUAR Y. 
 
 expected, he intended to give his experience to the public in a 
 more convenient form than his lectures presented. One of these 
 works relating to "Colours other than Aniline," was nearly com- 
 pleted before his last illness, and constitutes the first eleven 
 chapters of the present volume. Whilst rather exhausted with 
 this work, added to the attention required for the manufactures 
 in which he was engaged, he was chosen as one of the Jury of 
 the Vienna Exhibition. The summer of 1873 was sultry and un- 
 pleasant, and other causes may have operated to make it unhealthy; 
 but whatever the reason or combination of reasons may have been 
 (and we cannot doubt that his unceasing labours contributed), the 
 result was that Dr. Calvert returned in a very enfeebled state, and 
 a few days after his arrival in Manchester was seized with a fatal 
 illness, which terminated on the 24th of October of the same year. 
 He was a firmly built man, of middle height, and apparently of 
 unusual strength. He seemed to be younger in constitution than 
 his years indicated. His manner was pleasing and animated, and 
 he had great pleasure in communicating information. It is not 
 attempted in this notice to say to what extent his writings have 
 contributed to the advance of science, or the knowledge of manu- 
 factures, but in the latter department it is certain that his influence 
 was widely felt, and his friendly disposition enabled him to become 
 a frequent medium of communication between scientific men in 
 England and in France, in both of which countries he felt equally 
 at home. With these combined characteristics, the position he 
 made for himself was peculiar, and of its importance we may 
 judge partly by the fact that, although one to which many would 
 be glad to attain, it is not yet filled up; and, as Dr. Angus Smith 
 remarked at the Manchester Philosophical Society, "his death 
 was regretted not only by those who knew him as a chemist, but 
 also by those who but knew him as a man/' 
 
CONTENTS 
 
 CHAPTER I. 
 
 PAGE. 
 
 Introductory i 
 
 Natural Colours; Cause of Colours, i. — Analysis of White 
 Light ; the Spectrum, 2. — Nature of Colouring Mat- 
 ters, 3. — Action of Light on Colouring Matters, 6. — 
 Colouring Matters of Flowers; Cyanin, 7. — Xanthin, 8. 
 — Xanthein : Reducing Power of the Roots of Plants, 
 9. — Action of Electricity on the Colouring Matters of 
 Flowers, 10. — Action of Heat on Colouring Matters, 
 11. — Action of Chlorine on Colouring Matters, 12. — 
 Action of Hypochlorites on Colouring Matters: De- 
 colourising Power of Charcoal, 13. — Animal Charcoal: 
 Solubility of Colouring Matters; 14. — Bleaching Action 
 of Sulphurous Acid : Compounds of Metallic Oxides 
 with Colouring Matters ; Lakes, 16. — Theory of Mor- 
 dants ; Thorn's Experiments on Mordants, 17. — Oxi- 
 dising Effect of certain Salts on Colouring Matters, 18. 
 — 'Fast' and 'Loose' Colours, 19. — Effect of Heat and 
 Light on the Colours of Dyed Fabrics, 20. 
 
 CHAPTER II. 
 
 Madder 22 
 
 The Madder Plant, 22. — Madder Root; Preparation of 
 Madder; Composition of Madder, 23. — Avignon Mad- 
 ders, 'Paluds' and Rosees: Erythrozym: Rubian, 24. — 
 
xvi. CONTENTS. 
 
 PAGE. 
 
 Kuhlmann's Xanthin, 25. — Action of Erythrozym, of 
 Acids, and of Alkalis on Rubian, 29. — Formation of 
 Alizarin from Rubian, 31. — Verantin, 32. — Rubiretin, 
 Rubianin, Rubiacic Acid, 33. — Rubiacin, 34. — Sugar 
 in Madder: Ruberythic Acid; Decomposition of Ru- 
 berythic Acid into Alizarin and Sugar, 35. — Isalizarin, 
 Hydralizarin.and Pseudopurpurin, 36. — Purpuro xanthin, 
 37. — Preparation and Properties of Alizarin, 38. — 
 Conversion into Anthracene : Nitroalizarin,4i. — Amido- 
 alizarin, 42. — Alizarinamide, 43. — Anthraflavic Acid, 
 44. — Anthrapurpurin, 45. — Manufacture of Anthracene, 
 Properties of Anthracene, 46. — Conversion into Anthra- 
 quinone, Preparation of Artificial Alizarin, 48. — Caro, 
 Graebe, and Liebermann's Patent, 50. — Broenner and 
 Gutzkon's Patent, 54. — Anthracene Orange: Naphth- 
 azarin, 55. — Oxynaphthalic Acid, 56. — Purpurin and 
 its Derivatives, 58. — Optical Properties of Purpurin and 
 Alizarin, 60. — Detection of Purpurin and Alizarin, 62. 
 
 CHAPTER III. 
 
 Madder. — Continued 64 
 
 Use of Madder, 64. — Turkey or Adrianople Red, His- 
 torical, 65. — Processes for producing Turkey Red, 
 Oiling the Cloth, 66. — Mordanting the Cloth, Dyeing 
 the Cloth, 67.— Clearing the Dyed Cloth, 68.— Effect 
 of Oiling, 69. — Persoz' Explanation, 70. — Printing 
 Turkey Red, Miiller's Process, 71. — Calico Printing, 
 Mordants Employed, 72. — Recipes for Mordants, for 
 various Colours, 73. — Method of Printing Mordants, 
 76. — Ageing; Thorn's Process, 77. — Dunging, 78. — 
 Construction of Dyebeck, 79. — Method of Dyeing 
 with Madder; Use of Chalk in Madder Dyeing, 81.— 
 Soaping and Clearing Madder-Dyed Goods, 83. — 
 Manufacture of Garancin, 84. — 'Garancine Modifie'e:' 
 Utilisation of Waste Products, 85. — Dyeing Power of 
 Garancin, 86. — Advantages of Garancin over Madder : 
 
CONTENTS. xvii. 
 
 PAGE. 
 
 'Commercial Alizarin,' 87. — Garanceaux: Fleurs de 
 Garance, or Flowers of Madder, 88. — Alcohol from 
 Madder Washings, 89. — Madder Extracts, 90. — Leiten- 
 berger's Extract, 91. — Paraf's Extract: Kopp's Purpurin 
 and Green Alizarin, and Dyestuffs obtained from 
 them, 92. — Pernod's Extract, 95. — Pvien's Process for 
 Extracting Alizarin and Purpurin : Recipes for Dyeing 
 with Madder Extracts, 96. — Table of Colours obtained 
 by Printing a Mixture of Madder Extract with the 
 Acetates of various metals, 98. — Printing with Artificial 
 Alizarin, 100. — Recovery of Waste Colours; Scheurer's 
 Process, 101. — Koechlin's Process for the Recovery of 
 Waste Colour, 102. — Thom and Stenhouse's Process 
 for the Utilisation of Soap Waste : Manufacture of Mad- 
 der Lakes, 103. — Adulteration of Madder, 104. — Test- 
 ing the value of Madder, &c, 105. — Testing Madder- 
 Dyed Fabrics, 107. — Munjeet, 108. — Munjistin, 109 — 
 Chayaver, no. — Al' Root, or SooranjeefJ/<?w?^ Citri- 
 folia), Morindin and Morindone, in. 
 
 CHAPTER IV. 
 
 Red Dyewoods, Safflower, Alkanet 113 
 
 Red Dyewoods, Campeachy or Logwood, 113. — Hema- 
 toxylin, 114. — Hsematein, 115. — Reactions of Haema- 
 toxylin, 117. — Preparation of Logwood, 118. — Extract 
 of Logwood; Dyeing Purple with Logwood, 119. — Log- 
 wood Black, 120. — Brazil Wood, and Peach Wood or 
 Santa Martha Wood, 121. — Sapan Wood; Lima Wood; 
 The Colour-giving principle of these Woods, 122. — 
 Brazilin, and its Relation to Haematoxylin, 123. — 
 Brazilei'n, 124. — Reactions of the Brazil Wood Group : 
 Extracts of Brazil and Sapan Woods, 125. — Dingler's 
 Process; Dyeing with Brazil Wood Extract, 126. — 
 Pink Lakes — Venetian Lake : SandalWood,Barwood, and 
 Camwood or Kambe Wood, 128. — Colouring principle 
 of Sandal Wood, 129. — Mock Turkey Red, 131. — Re- 
 a 
 
xviii. CONTENTS. 
 
 PAGE. 
 
 actions of Sandal Wood and Barwood, 132. —Sorgho, 
 133. — Sorgho Carmine or Sorgho Red; Alkanet; 
 Anchusin, 134. — CEnolin, the Colouring principle of 
 Wines: Safflower, 135. — Preparation of Safflower: 
 Composition of Safflower, 136. — Carthamin, 137. — 
 Yellow Colouring Matter of Safflower : Dyeing with 
 Safflower, 138. 
 
 CHAPTER V. 
 
 Indigo 14° 
 
 History of Indigo: Plants which furnish Indigo, 140. — 
 Manufacture of Indigo, 141. — Woad or Pastel, 143. — 
 Tein hoa tein ching (Is at is Indigotica): Polygonum tincto- 
 rium. 144. — Colouring principle of the Indigoferae, 
 144. — Indican, Schunck's Researches, 146. — Schunck's 
 Apparatus for Evaporation, 147. — Action of Acids on 
 Indican, 150. — Indirubin, 151. — Indiretin, Indihumin, 
 and Indiglucin, 153. — Action of Alkalis on Indican ; Indi- 
 canin, 155. — Oxindicanin, 157. — Pure Indigotin, 158. — 
 Isatin, 159. — Isatic Acid; Isatyde, 160. — Sulphisatyde 
 and Disulphisatyde : Indin and its Derivatives: Com- 
 pounds obtained with Isatin and Ammonia, 161. — Ac- 
 tion of Hydriodic Acid on Isatin; Isatopurpurin and 
 Isatoflavin: Indigotic or Nitrosalicylic Acid, 162. — Pic- 
 ric Acid from Indigo, 163. — Action of Chlorine on In- 
 digo, 164. — Chlorisatin, and Dichlorisatin, 165. — Chlo- 
 ranil or Perchlorquinone : Bromisatins, 166. — Chrysanilic 
 Acid: Anthranilic or Phenylcarbamic Acid, 167. — 
 Aniline from Indigo: Synthesis of Indigo, 169. — Diox- 
 indol or Hydrindic Acid, 170. — Oxindol, and Indol, 
 171. — Baeyer and Emmerling's Experiments on the 
 Reduction of Isatin, 173. 
 
 CHAPTER VI. 
 
 Indigo — Continued 175 
 
 Indigosulphonic Acids; Sulphopurpuric Acid, 175. — 
 
CONTENTS. xix. 
 
 PAGE. 
 
 Sulphindigotic Acid, 176. — Hyposulphindigotic Acid, 
 177. — Saxony Blue, and Indigo Carmine, 178. — Bailey's 
 Indigo Carmine, 179.— Action of Alkalis on the Indigo- 
 sulphonic Acids; Sulphoviridic Acid, 180. — Sulphorufic 
 Acid, and Sulphopurpuric Acid, 181. — White or Reduced 
 Indigo; Dumas' Process for Preparing White Indigo, 
 182. — Schiitzenberger and Lalande's Process, 184. — 
 Lightfoot's Process for Chintzes, 186. — Schlumberger's 
 Process : Steam Style : Purification of Indigo, 188. — 
 Characters of Bengal Indigo, 189. — Chevreul's Analysis 
 of Indigo: Testing Indigo, 191. — Cold Vat: Recovery 
 of Waste Indigo, 197. — Pulverisation of Indigo, 198. — 
 Cohen's Process for Cold Vat, 199. — Resist or Reserve 
 Process, 200. — Discharge Process, 201. — China Blue: 
 Indian Vat for Dyeing Wool, 203. — Leuch's Vat, 204. — 
 Formation of Indigo in the Human System, 205. 
 
 CHAPTER VII. 
 
 Cochineal, Kermes, Gum-lac, Lac Dye, Lac Lake, and 
 
 Murexide 206 
 
 History of Cochineal, 206. — Preparation of Cochineal, 
 207. — Composition of Cochineal according to John : 
 Preparation of Carminic Acid, 209. — Carmine red, 
 211. — Properties of Carmine Acid, 212. — Nitrococcusic 
 Acid: Reactions of Cochineal, 213. — Adulteration of 
 Cochineal, and Testing Cochineal, 214. — Dyeing with 
 Cochineal, 216. — Ammoniacal Cochineal, and Carmina- 
 mide: Carmine Lakes, 218. — Preparation of ' Carmine,' 
 219. — Florentine Lake: Kermes, 220. — Uses of 
 Kermes, 221. — Stick Lac, 222. — Composition of Stick 
 Lac; Seed Lac, 223. — Composition of Seed Lac; 
 Shell Lac; Composition of Shell Lac; Lac Lake, 224. — 
 Composition of Lac Lake; Lac Dye; Brooke's Lac 
 Dye: History of Murexide, 225. — Preparation of Murex- 
 ide, 226. 
 
xx. CONTENTS. 
 
 PAGE. 
 
 CHAPTER VIII. 
 
 Orchil, Cudbear, and Litmus 228 
 
 Discovery of Orchil: Nature of Lichens, 228. — Species of 
 Lichens used for the Preparation of Orchil, and Manufac- 
 ture of Orchil, 229. — French Purple, 232. — Process for 
 Testing Lichens : Uses of Orchil : Discovery of Orcin, 
 233. — Preparation of Orcin and Erythrite, 234. — 
 Properties of Orcin, 235. — Haloid Derivatives of Orcin: 
 Nitro Derivatives of Orcin, 236. — Orcein, 237. — 
 Methyl, Ethyl, and Amyl Orcins, 238. — Erythrin or 
 Erythric Acid, 239. — Picroerythrin : Lecanoric Acid, or 
 Lecanorin, 240. — Properties of Lecanoric Acid, 241. — 
 Ethylic Orsellinate : Preparation of Picroerythrin, 242. — 
 Properties of Picroerythrin: Erythrite or Erythromannite, 
 243. — Tetranitroerythrite : Usnic acid, 244. — Evernic 
 Acid, and Everninic Acid: Cladonic Acid, or j3- usnic 
 Acid, 245. — Orsellinic Acid, or Orsellesic Acid, 246. — 
 Other Compounds obtained from the Lichens : Summary : 
 Cudbear, 247. — Litmus, or Lacmus, 248. — Tournesol: 
 Resorcin, 249. — Azoresorcin Derivatives, 250. — 
 'Eosin,' or Tetrabromofluorescein, 251. 
 
 CHAPTER IX. 
 
 Quercitron, Fustic, Persian Berries, Weld, Aloes, 
 
 Turmeric, Annatto, Ilixanthin, &c, Lo-Kao... 253 
 Quercitron, 253. — Reactions of Quercitron Bark, 25L — 
 Quercitrin: Decomposition of Quercitrin by Acids, 
 255. — Isodulcite, and Quercetin, 256. — Action of Potas- 
 sium Hydrate on Quercetin, 257. — Quercetic Acid, 
 Quercimeric acid, and Paradatiscetin, 258. — Phloroglu- 
 cin : Reducing Action of Sodium Amalgam on Quercetin, 
 259. — Flavin, 260. — Dyeing with Quercitron Bark and 
 Flavin, 261. — Old Fustic, 262. — Reactions of Old 
 Fustic; Colouring Matters of the Wood, 263. — Morin- 
 tannic Acid, or Maclurin, 264. — Machromin, 265. — 
 
CONTENTS. 
 
 Moric Acid, or Morin, 266. — Analogy between Quer- 
 cetin and Morin, 267. — Dyeing with Old Fustic: Young 
 Fustic, 268. — Fustin : Reactions of Young Fustic, 269. — 
 Dyeing with Young Fustic: Persian Berries, whence 
 obtained ; Reactions of Persian Berries, 270. — Kane's 
 Chrysorhamnin and Xanthorhamnin ; Results of Gel- 
 latly's Investigations, 271. — Observations of Hlasiwetz, 
 Bolley, Schiitzenberger, and Berteche; Lefort's Rham- 
 nagin and Rhamnin, 272. — Summary of Results, 273. — 
 Melin from Waifa: Dyeing with Persian Berries, 274. — 
 Dutch Yellow, 275. — Weld; Reactions of Weld, 276. — 
 Luteolin, 277. — Use of Weld : Source of Aloes, 278. — 
 Socotrin or Bombay Aloes, Barbadoes Aloes, Natal 
 Aloes, and Cape Aloes, 279. — Preparation of Barbaloin, 
 280. — Haloid Derivatives of Barbaloin: Nataloin, and 
 Socaloin, 281. — Aloetic Acid, 282. — Chrysammic Acid, 
 283. — Hydrochrysammide : Colours obtained with 
 Aloes: Turmeric, 284. — Composition of Turmeric: 
 Curcumin, 285. — Rosocyanin : Dyeing with Turmeric, 
 287. — Preparation and Composition of Annatto, 
 288. — Testing Annatto, 289. — Colouring Matters of 
 Annatto; Orellin and Bixin, 290. — Uses of Annatto: 
 Chica, or Carajara, 291. — Saffron; Crocin: Barberry 
 Root, 292. — Berberine and its Sources, 293. — Gam- 
 boge, 294. — Composition of Gamboge, 295. — Ilix- 
 anthin: Yellow Colouring Matters from Lichens,296. — 
 Purree, or Indian Yellow; Euxanthic Acid, 297. — 
 Euxanthone: Rhubarb; Chrysophanic Acid: Rutin, 
 298. — Scoparin, 299. — Taigu, or Tayegu Wood; 
 Tayguic Acid, 300. — Wongshy, or Hoang-tchy : Carotin, 
 &c: Rottlerin : Lo-kao, or Chinese Green, 301. — Lokain, 
 303. — Lokaetin, 304. — Sap Green, or Bladder Green : 
 Preparation of Chlorophyll, 305. — Fremy's Phyllox- 
 anthin, and Phyllocyanin, 307. — Stokes' Examination 
 of Chlorophyll, 308. — Lommel's Observations : Xyloch- 
 loeric Acid : Printing Chlorophyll, 309. 
 
xxii. CONTENTS. 
 
 PAGE. 
 
 CHAPTER X. 
 
 Tannin Matters 310 
 
 Nature of Tannin Matters, 310. — Two Classes of Tannins: 
 Preparation of Tannic or Gallotannic Acid, 311. — 
 Decomposition of Tannin by Heat : Schiff's Researches 
 on Tannin, 312. — Digallic Acid : Tannoxvlic or Rufi- 
 tannic Acid : Gallic Acid, 313. — Preparation and Pro- 
 perties of Gallic Acid, 314. — Rufigallic Acid, 315. — 
 Decomposition of Gallic Acid by Heat; Preparation 
 of Pyrogallic Acid, or Pyrogallol, 316. — Gallein, and 
 Gallin, 31S. — Ccerulein, 319. — Coerulin,, 320. — Ellagic 
 Acid: Mode of Formation of Gall-nuts, 32 r. — Com- 
 position of Gall-nuts: Reactions of a Solution of Gall- 
 nuts, 322. — Knopperns: Chinese Galls, or Japanese 
 Galls. 2Hi. — Valonia, 324. — Cultivation of Sumach; 
 Reactions of a Decoction of Sumach, 325. — Uses of 
 Sumach, 326. — Bablah, Babool, or Xeb-neb, 327. — 
 Chesnut Bark, Dividivi, Myrobalans, Oak Bark, and 
 Spruce Bark or Hemlock Tree Bark, 328. — Compounds 
 obtained from Walnut Husks: Hennis, 329. — Prepara- 
 tion of Catechu : Source of Gambier : Kino, or ' Gum 
 Kino,' 330. — Bombay, Bengal, and Gambier Catechu, 
 33 l - — Reactions of Catechu; Adulteration of Catechu, 
 S3 2 - — Catechutannic Acid, 3^^. — Catechin, or 
 Catechuic Acid, 334. — Products of the Decomposition 
 of Catechin, 335. — Pyrocatechin, 336. — Dyeing and 
 Printing with Catechu; Catechu Browns, 337. — 
 Estimation of Tannin, 33S. — Amount of Tannin in 
 various Vegetable Substances, 340. 
 
 CHAPTER XI. 
 
 Ox the Examination of Colouring Matters and 
 
 Coloured Fabrics 342 
 
 Uses of the Colorometer, 242. — Houton-Labillardie're's 
 Colorometer, 343. — Collardeau's Colorometer, and Du- 
 
CONTENTS. xxiii. 
 
 PAGE. 
 
 bosc and Mene's Colorometer, 344. — Wilson's Coloro- 
 meter, 345. — Spectroscopic Examination of Colours, 
 346. — Use of Oxidising Agents: Comparison of the 
 Dyeing Powers of Dyestuffs, 347. — Adulteration of 
 Dyestuffs, 348. 
 
 CHAPTER XII. 
 
 Benzene, Aniline, and Magenta 350 
 
 Constituents' of Coal-tar, 350. — Historical Account of 
 Aniline, 351. — Distillation of Coal-tar, and Extraction of 
 Aniline from Coal-oil, 352. — Preparation of Benzene 
 from Light Oil,, 353. — Benzene from Benzoic Acid; 
 Properties of Benzene, 354. — Manufacture of Nitro- 
 benzene, 355. — Dinitrobenzene : Preparation of Aniline 
 from Nitrobenzene, 356. — Manufacture of Aniline, 
 357. — Properties of Aniline, 358. — Formation of 
 Magenta: Toluene, 359. — Nitrotoluenes, 360. — Tolu- 
 idines: Commercial Aniline, 362. — Historical Account 
 of Magenta, 363. — Manufacture of Magenta, 365. — 
 Purification of Magenta, 367. — Rosaniline, 368. — 
 Salts of Rosaniline, 369. — Leucaniline: Hydrocyanros- 
 aniline, 370. — Manufacture of Rosaniline, and of 
 Rosaniline Acetate, 371. — Caro and Dale's Process 
 for Magenta, Laurent and Casthelaz Process, 372. — 
 Coupler's Process: Rosotoluidine, or Toluidine Red, 
 373. — Xylidine Red: Pararosaniline : Dyeing with 
 Magenta, 374. — Printing Silk and Wool with Magenta, 
 Dyeing Cotton and Mixed Fabrics with Magenta; 
 377. — Printing Cotton with Magenta: Magenta Purple, 
 378. — Adulteration of Magenta, 379. — Safranine, or 
 Saffranine, 380. — Geranosine, Ponceau, and Cerise, 
 382. — Ulrich's Scarlet, 383. 
 
 CHAPTER XIII. 
 
 Aniline Violets and Aniline Blues 384 
 
 Aniline Violets : Discovery of Mauve, 384. — Manufacture 
 
xxiv. CONTENTS. 
 
 PAGE. 
 
 of Mauve, 385. — Mauveine, 386. — Phcenicine, 387. — 
 Runge's Blue : Various Processes for obtaining Mauve, 
 388. — 'Violet Imperial;' Monophenylrosaniline, 390. — 
 Diphenylrosaniline : 'Regina Purple,' 391. — Kopp's 
 Violet: Mauvaniline and Violaniline, 392. — Methyl 
 and Ethyl Rosanilines, 393. — Manufacture of Hofmann 
 Violet, 395. — Ethylmauveine or 'Dahlia,' 396. — Manu- 
 facture of Methylaniline, and Paris Violet, 397. — 
 Methylaniline and Ethylaniline from ' Hofmann Gum : ' 
 'Dorothea Violet,' 398. — Benzyl Chloride: Violets from 
 Tertiary Monamines, 399. — 'Britannia Violet:' Alde- 
 hyde Violet: Dyeing with Aniline Violet6, 400. — Dale's 
 Recipes for Printing, 401. — Aniline Blues; 'Bleu de 
 Paris,' and 'Bleu de Mulhouse,' 402. — Manufacture of 
 'Bleu de Lyon,' 403. — Purification of 'Bleu de Lyon;' 
 'Bleu Lumiere' or 'Night Blue,' 404. — Bardy's Process 
 for Aniline Blue and Violet, 405. — Difference between 
 'Bleu de Paris' and 'Bleu de Lyon,' 406. — Nicholson's 
 Soluble Blue, 407. — Toluidine Blue, 408. — Manufac- 
 ture of Diphenylamine, 409. — Diphenylamine Blue, 
 410. — Azodiphenyl Blue : Dyeing with Aniline Blue, 41 1. 
 
 CHAPTER XIV. 
 
 Aniline Green. — Aniline Vellow 414 
 
 Emeraldine: Discovery and Preparation of Aldehyde 
 Green, 414. — Historical Account of Iodine Green, 
 416. — Wanklyn's Process; Hofmann and Girard's Pro- 
 cess, 417. — Manufacture of Iodine Green, 418. — Solu- 
 ble Green, and Crystallised Green, 420. — Transforma- 
 tion of Iodine Green. 421. — Perkins Green, and Methyl 
 Green, or Methylaniline Green, 422. — Dyeing with 
 Aniline Greens, 423. — Aniline Yellows; Chrysaniline, 
 or Phosphine, 425. — Chrysotoluidine; Purification of 
 Chrysotoluidine, 426. — Preparation of Chrysotoluidine 
 from Toluidine ; Properties of Pure Chrysotoluidine, 
 428. — Scheurer-Kestner's Orange: Diazoamidobenzene 
 
CONTENTS. xxv. 
 
 PAGE. 
 
 and Amidodiphenylimide, 429. — Vogel's Zinaline: 
 Adulteration of Aniline Yellow, 430. 
 
 CHAPTER XV. 
 
 Aniline Browns and Aniline Black 432 
 
 Aniline Maroons and Browns: Girard and De Laire's 
 Maroon: Schultz' Garnet, 432. — Jacobsen's Browns; 
 Koechlin's Brown, 433. — Wise's Brown, and Sieberg's 
 Brown, 434. — Dyeing with Aniline Brown : Aniline Black, 
 435. — Lightfoot's Processes, 436. — Lauth's Process, 
 437. — Koechlin's Recipe, 438. — Sacc's Recipe for Olive 
 Browns : Dullo's Black : Lauth's Manganese Mordant, 
 439. — Spirk's Recipes, 440. — Aniline Black with Al- 
 bumen : Jarossen and Mullens Process : Schlumberger's 
 Process, 441. — Nature of Aniline Black, 442. — Light- 
 foot's Experiments, 443. — Rheineck's Experiments; 
 Nigraniline, 444. — Qualities of Aniline adapted for 
 Aniline Black, 445. — Process for Aniline Black with 
 Potassium Dichromate, 446. — Aniline Black on Wool : 
 Laiiber's Aniline Grey, 448. — Casthelaz Grey, 449. 
 
 CHAPTER XVI. 
 
 Phenol, Cresol, and Naphthalene Colours 450 
 
 Phenol or Carbolic Acid, 450. — Picric Acid or Trinito- 
 phenol; Manufacture of Picric Acid, 452. — Properties 
 of Picric Acid; Dyeing with Picric Acid, 454. — Picric 
 Acid as a Test for Cotton in Mixed Fibres : Adultera- 
 tion of Picric Acid, 455. — Picramic Acid or Dinitro- 
 amidophenol: Isopurpuric Acid, 456. — Difference be- 
 tween Murexide and Isopurpuric Acid, 457. — Dyeing 
 with Isopurpurates : Rosolic Acid, 458. — Manufacture 
 of Corallin, 459. — Crystalline Corallin: Formation of 
 Corallin, 460. — Printing with Corallin, 461. — Peonine 
 or Red Corallin, 462. — Dyeing and Printing with 
 Peonine and Corallin, 463. — Azulin, 464. — Pseudo- 
 corallin, 465. — Aurin, 466. — Leukaurin, 467. — Printing 
 
i. CONTENTS. 
 
 with Aurin : Phenicienne or Rothine : Fol's Yellow, 468. 
 — 'Campo Bello Yellow:' Cresol Colours: Gold Yellow, 
 469. — Victoria Yellow: Xaphthalene Colours: Naphtha- 
 lene, 470. — Dinitronaphthol, 471. — Manchester Yellow 
 or 'Martius' Yellow,' 472. — Xaphthylpurpuric Acid, and 
 Indophane : Resorcin Indophane, 473. — Chloroxy- 
 naphthalic Acid, 474. — Carminaphtha : Xitroxynaph- 
 thalic Acid or 'French Yellow:' Xaphthylamine, 475. 
 — Preparation of Xitronaphthalene, and Manufacture of 
 Xaphthylamine, 476. — Azodinaphthyldiamine, 477. — 
 Rosanaphthylamine or 'Magdala Red,' 478. — Xaph- 
 thylamine Violet, 479. — Ballb's Violet, 480. 
 
 PAGE. 
 
 AP P EX D IX. 
 
 Tables for distinguishing the different Colouring 
 Matters fixed on Tissues by Printing or 
 
 Dyeing 
 
 Blue Colouring Matters, including — Vat Indigo, Indigo 
 Carmine, Alkaline Sulphindigotates, Saxony Blue, 
 Prussian Blue, Logwood Blue, Aniline Blue, and Ultra- 
 marine, 482. — Yellow Colouring Matters, including — 
 Quercitron, Persian Berries, Old Fustic, Weld, Barberry 
 Root, Turmeric, Annatto, Picric Acid, Chrome Yellows, 
 Ochre and Orpiment, 484. — Red Colouring Matters, 
 including — Cochineal, Brazil Wood, Madder Reds, 
 SaihWer, Murexide, and Aniline Reds, 486. — Green 
 Colouring Matters, including — 1, Indigo Blue, and a 
 Vegetable Yellow; 2, Logwood Blue, and a Vegetable 
 Yellow; 3, Lokao; 4, Aniline Green; 5, Aniline Blue 
 and Picric Acid, or Vegetable Yellow; 6, Scheele's 
 Green; 7, Oxide of Chromium, 488. — Purple Colours, 
 including — Mauve, Aniline Purple, Hofmann's Aniline 
 Violet, Madder Purples, Alkanet, Orchil, and Logwood 
 
CONTENTS. xxvii. 
 
 PAGE. 
 
 Purple, 490. — Brown Colours, including — Madder, 
 Catechu, Browns produced with Red Dyewoods, Man- 
 ganese, and the Brown produced by the employment 
 of Blue, Yellow, and Red on Woollen, 492. — Black and 
 Grey Colours, including — Logwood with Iron Mordant, 
 Tannin, Chrome Black, Madder Black, Black with 
 Bottom or Ground of Vat Indigo, and Aniline Black, 
 494. 
 
 Table of Properties and Reactions of various Com- 
 pounds OBTAINED FROM MADDER 496 
 
xxviii. CONTEXTS. 
 
 LIST OF PRINTED AND DYED PATTERNS. 
 
 PAGE. 
 
 Turkey red as dyed, Messrs. Steiner and Co 68 
 
 ,, after first clearing, Messrs. Steiner and Co 68 
 
 ,, finished, Messrs. Steiner and Co 69 
 
 Madder purple, Messrs. Symonds, Cunliffe, and Co 74 
 
 Madder red and pink, Messrs. Symonds, Cunliffe, and Co 75 
 
 Effect produced by a six-colour machine, Messrs. Walter Cram and Co. . 77 
 
 Madder style, mordanted cloth, Messrs. Symonds, Cunliffe, and Co 79 
 
 ,, after dyeing, Messrs. Symonds, Cunliffe, and Co 83 
 
 cleared, Messrs. Symonds, Cunliffe, and Co 83 
 
 Garancin s:; Wood and Wright 87 
 
 Pincoffine, or 'commercial alizarin,' Messrs. Salis Schwabe and Co 88 
 
 Orange extract of madder : red, Messrs. Dollfus, Meig, and Co 95 
 
 ,, ,, purple, Messrs. Dollfus, Meig, and Co 95 
 
 Extract of garancin, with chromium mordant, M. H. Koechlin 100 
 
 ,, ,, uranium mordant, M. H. Koechlin 100 
 
 Topical style, with artificial alizarin. M. H. Koechlin 101 
 
 Logwood purple, Messrs. Wood and Wright 1 20 
 
 Logwood black, Messrs. Heys and Co 120 
 
 Brazil-wood rose colour, M. H. Koechlin 127 
 
 Mock Turkey red, Messrs. Wood and Wright 132 
 
 Schiitzenberger and Lalande's process for indigo, Messrs, Edmund Potter 
 
 and Co 185 
 
 Lightfoot's process for chintzes, Messrs. Grafton and Co 187 
 
 Indigo, dark blue, with light blue reserved, Messrs. Wood and Wright. 201 
 
 Same pattern, with discharge printed on, Messrs. Wood and Wright 202 
 
 Cochineal pink, steam style, Messrs. Wood and Wright 217 
 
 Ammoniacal Cochineal, Messrs. Heys and Co 217 
 
 Silk dyed with French purple, Messrs. Mamas and Co 232 
 
 Eosin, M. H. Koechlin 252 
 
 Quercitron yellow, Messrs. lit;.- and Co 261 
 
 Extract of Madder and Quercitron, M. H. Koechlin 262 
 
 Fustic, Messrs. Heys and Co 268 
 
 Persian berries, (yellow), Messrs. Wood and Wright 2 74 
 
 Persian berries, (green, with Prussian blue) Messrs. Wood and Wright... 275 
 
 Lo-kao on silk, Messrs. Mamas and Co 302 
 
 Gallein, M. H. Koechlin 319 
 
 Coerulein, M. H. Koechlin 320 
 
 Catechu brown (light shade), Messrs. Salis Schwabe and Co 337 
 
CONTENTS. xxix. 
 
 PAGE. 
 
 Catechu brown (dark shade), Messrs. Salis Schwabe and Co 338 
 
 Wool dyed with magenta, M. G. Schaeffer 376 
 
 Magenta printed on cotton, M. H. Koechlin 378 
 
 Safranine printed on cotton, M. H. Koechlin 381 
 
 Hofmann's violet RRR on wool, M. G. Schaeffer 394 
 
 ,, ,, B on wool, M. G. Schaeffer 394 
 
 Cotton printed with Hofmann violet, M. H. Koechlin 401 
 
 Wool dyed with aniline blue, M. G. Schaeffer 408 
 
 Nicholson's blue on cotton, M. H. Koechlin 413 
 
 Aldehyde green on cotton, M. H. Koechlin 415 
 
 Wool dyed with iodine green, M. G. Schaeffer 420 
 
 Methylaniline green printed on cotton, M. H. Koechlin 423 
 
 Aniline yellow on wool, M. G. Schaeffer 429 
 
 Wool dyed with aniline brown, M. G. Schaeffer 435 
 
 Aniline black on cotton, M. H. Koechlin 448 
 
 Picric acid on wool, M. G. Schaeffer 455 
 
 Wool dyed with aurin, M. G. Schaeffer 461 
 
 Yellow corallin on cotton, M. H. Koechlin 462 
 
 Corallin on wool, M. G. Schaeffer 464 
 
 LIST OF ENGRAVINGS. 
 
 Spectra of purpurin and alizarin 61 
 
 Printing machine 76 
 
 Arrangement of bath for dunging 78 
 
 Arrangement of dyebeck 80 
 
 The indigo plant 141 
 
 Pastel or Woad 144 
 
 Polygonium tinctorium 145 
 
 Schunck's apparatus for evaporation (cross section) 147 
 
 ,, ,, ,, (elevation) 148 
 
 Apparatus for producing self colours with indigo 202 
 
 Rocella fuciformis 229 
 
 Houton-Labillardiere's colorometer 343 
 
 Collardeau's colorometer 344 
 
 Wilson's colorometer 345 
 
DYEING AND CALICO PRINTING. 
 
 INTRODUCTION. 
 
CHAPTER I. 
 Introductory. 
 
 NATURE has given to the animal and vegetable kingdoms 
 an infinite variety of colours which from their beauty, their 
 brilliancy, and their purity may vie with the colours of the 
 rainbow, and these phenomena of colour have from time 
 immemorial attracted the attention of enquiring minds and 
 awakened a desire to understand the causes of their pro- 
 duction. 
 
 The earlier chemists considered that they were due to 
 the presence of a peculiar principle in the cells of organic 
 tissues, which could be acted on by external agents, and 
 that the particular colour produced was determined by the 
 action which took place. Had this view been confined to 
 the colouring principles to be found in the leaves and 
 flowers of plants merely, it would not have been far from 
 the truth, for recent researches have shown that, in the 
 production of all the differences of colour, shade, and tone 
 which we see exhibited in such profusion in the beautiful 
 flowers and foliage of summer, and in the variety and rich- 
 ness of tint in autumn, only two principles are concerned. 
 On the other hand, it was found from a more careful study 
 of the nature of the colours used in dyeing, and a comparison 
 of those colouring matters which had been obtained from 
 certain animal and vegetable substances, and applied to the 
 ornamentation of fabrics, that there were nearly as many 
 B 
 
 D. H. HILL LIBRARY 
 
 North Carolina State College 
 
2 DYEING AND CALICO PRINTING. 
 
 colouring principles as colours, for it was impossible to class 
 the brilliant crimson of the cochineal insect with the yellow 
 extracted from weld, or with the beautiful blue obtained 
 from the indigofera. 
 
 When this idea was abandoned, the differences of colour 
 were attributed to a difference in the chemical constitution 
 of the various coloured compounds or colouring principles 
 contained in the cells or tissues, and step by step, by 
 patient observation and persevering study, it has been 
 proved beyond all doubt that there is a considerable 
 number of proximate principles of very different compo- 
 sition and varying widely in properties, but which are 
 classed together under the name of colouring matters or 
 colour-giving principles. It is to the study of these com- 
 pounds that our attention is at present especially directed. 
 
 Before however commencing this study we must consider 
 what is the true cause of colour. 
 
 We may define colour as the impression that the light 
 reflected from a surface makes upon the eye. 
 
 If a beam of sunlight is admitted into a dark room, 
 through a vertical slit in the shutter, and is then allowed 
 to fall on a vertical glass prism, it will enter it, but on 
 emerging again, will be found to be deflected from its 
 previous path and at the same time decomposed. If the 
 beam of light after its passage through the prism be now 
 received on a white screen, an elongated and brightly 
 coloured image will be seen, which is called the spectrum. 
 This may be roughly mapped out into seven bands of dif- 
 ferent colours, occurring in the following order : — red, 
 orange, yellow, green, blue, indigo, violet. 
 
 Among the bodies found in nature, some absorb the 
 whole of the coloured rays falling upon them, and appear 
 to the eye to be black; others reflect all the rays, and are 
 said to be white; others, again, have the power of decom- 
 posing light, absorbing part of the rays and reflecting others. 
 
CAUSE OF DIFFERENT COLOURS. 3 
 
 It is this power of reflecting certain rays which we allude 
 to when we say that anything is coloured. A body is red 
 when it absorbs the other coloured rays, and reflects those 
 which give us the impression of red; it is blue if the blue 
 rays only are reflected, and so on; thus the innumerable 
 shades of colour which we see are caused by the varied 
 combinations of the unabsorbed rays. 
 
 It is evident, therefore, that colour is a physical effect 
 produced on the surface of the things that we see, and as 
 the same bodies nearly always appear to us of the same 
 colours, this property of absorbing certain coloured rays 
 and reflecting others must depend on the condition of their 
 surfaces, and on the chemical nature of some of their con- 
 stituents. In fact we can isolate certain organic principles 
 from coloured organic bodies, which when in a state of 
 purity are remarkable for the variety and intensity of their 
 shades; and these matters, among all the substances of 
 which plants and animals are composed, may therefore 
 reasonably be regarded as possessing the power of acting 
 on light and reflecting certain rays to the exclusion of 
 others. The substances endowed with these properties are 
 what we call the colouring matters or colouring principles 
 of bodies. 
 
 On this account Chevreul has defined the art of dyeing 
 to consist in fixing on fabrics by means of molecular 
 attraction, matters which act on light in a different manner 
 from the surface of the fibre itself. 
 
 Colouring matters are found in all parts of the animal 
 and vegetable kingdom. We find roots, such as madder, 
 and turmeric; stems of trees, as logwood, and sandal-wood; 
 bark, as quercitron; leaves, flowers, fruits, and seeds as 
 Persian berries, all more or less strongly coloured ; again, 
 the liquids circulating in different parts of the body, as the 
 blood, bile, &c, and even whole animals, such as cochineal 
 and kermes, sometimes present very brilliant colours. 
 
4 DYEING AND CALICO PRINTING. 
 
 The colouring matters are scarcely ever found in the 
 various organisms which enclose them in a pure state, but 
 are mixed with other matters, some of which are derived 
 from or are similar to them, thus rendering their separa- 
 tion a work of great difficulty; on this account compara- 
 tively few have been obtained in a state of absolute purity. 
 It was not until about sixty years ago that any syste- 
 matic study of the colouring principles of the known dye- 
 stuffs was attempted. Since that time, however, many 
 careful researches have been made, which have included 
 both methods of isolation of the colouring principles, the 
 action of chemical reagents on those principles, and pro- 
 cesses for fixing them on fabrics. 
 
 Foremost among those who have worked on this subject 
 stands M. Chevreul, who by his careful and successful 
 observation has thrown so much light on the constitution 
 of these bodies, and who perhaps, more than any other 
 man, has rendered the art of dyeing and calico-printing 
 one of the most interesting applications of chemistry to 
 the arts. The researches of Robiquet, Heeren, Kane, 
 Schunck, Gaultier de Claubry, Persoz, Runge, Kuhlmann, 
 Erdmann, Bolley, Stenhouse, Fremy and Cloez, Perkin, 
 Martius, Girardin, and many others too numerous to men- 
 tion, have also rendered valuable service in this field. 
 
 Of the colouring matters which have been isolated, some 
 are composed of carbon, oxygen, and hydrogen only, whilst 
 others contain nitrogen also. The fact of their being 
 derived from the animal or vegetable kingdom does not 
 appear to determine the presence or absence of nitrogen, 
 for some of those obtained from vegetables contain nitro- 
 gen, whilst some of those obtained from animals are free 
 from nitrogen. 
 
 The colours most common in the organic kingdom are 
 reds, blues, and greens, but the latter colour is very alter- 
 able and difficult to separate without injury; recourse has 
 
ORGANIC COLOURING MATTERS. 5 
 
 therefore been had to mineral matters of that colour, or a 
 mixture of blue and yellow has been used. Some years 
 ago, however, the green colour from the leaves and stalks 
 of certain plants was imported into Europe, from China, 
 under the title of Lo-kao, and was extensively used. It 
 was afterwards manufactured in France, but is now to a 
 great extent superseded by the coal-tar greens. 
 
 Strictly speaking, there are no blacks found in the organic 
 kingdom; browns are formed by the alteration of yellow 
 colouring matters, and are found principally in the barks of 
 trees, the husks of some fruits, and in some milky and resi- 
 nous secretions which have absorbed oxygen from the air. 
 
 Many observations lead to the conclusion that the prin- 
 ciples which give to the dyer such beautiful colours are 
 in themselves colourless, and become coloured only on 
 contact with the oxygen of the atmosphere. This may 
 be especially noticed in the freshly gathered leaves of the 
 Indigofera, or in the fresh roots of the madder plant, 
 which when growing are both without colour, but soon 
 alter on exposure to the atmosphere, becoming blue and 
 red respectively. The colour-giving lichens are also in 
 themselves colourless, and only yield their colours under 
 the influence of air and alkalis. Brazil and logwoods, 
 when freshly cut, are of a yellowish tint, but both become 
 red on exposure to the air. It is also a matter of common 
 observation that articles of furniture, made of oak, ma- 
 hogany, or walnut, become darker by age. 
 
 The yellow colouring matters of weld, quercitron, and 
 fustic, are, with equal facility, affected by exposure to the 
 atmosphere, soon becoming of a brownish hue. The decoc- 
 tions of these red and yellow colouring matters are even still 
 more rapidly affected, and if the time of exposure is suffi- 
 ciently prolonged, crystals of the colouring principles 
 separate, which cannot be obtained from the woods in a 
 livingr state. 
 
6 DYEIXG AXD CALICO PRINTING. 
 
 A very striking illustration of the influence of both light 
 and oxygen, in the formation of certain colouring matters 
 from colour-giving principles, was published some years 
 ago by M. Amaudon. He dipped a sheet of blotting 
 paper in an alcoholic solution of guaiacum resin, and dried 
 it quickly in a stove, out of contact with light. He then 
 cut strips from this sheet, and placed them in bottles con- 
 taining oxygen, one of which was kept in the dark, while 
 the other was exposed to direct sun-light. The latter 
 rapidly acquired a fine blue colour, while the former 
 remained unchanged. On exposing similar strips to sun- 
 light, in bottles containing nitrogen and hydrogen, no change 
 took place. If the paper, coloured blue, be exposed to the 
 more refrangible rays of the spectrum, or a gentle heat be 
 applied, the colour is destroyed by a further oxidation. 
 
 On the other hand, when oxygen is removed from many 
 of the colouring matters by means of reducing agents, such 
 as nascent hydrogen, 'sulphuretted hydrogen, the alkaline 
 sulphides, &c, they become colourless, but if again exposed 
 to the air, a reabsorption of oxygen takes place and the 
 colour returns. For example, when an infusion of litmus 
 is shaken in a closed flask, with a little sulphuretted hydro- 
 gen, the blue colour in the course of a few minutes passes 
 into a greenish yellow; but, on pouring it out into a shallow 
 vessel, and exposing it to the air, the blue colour rapidly 
 reappears. 
 
 From these facts it may be inferred that most of the 
 colouring matters, which have been isolated, are the pro- 
 ducts of the oxidation or the decomposition of principles 
 in the plants, either colourless or only slightly coloured; 
 these may be considered as colourable principles, which 
 by absorption of oxygen become gradually converted into 
 colouring matters. 
 
 These various principles have in general received names 
 derived from the animals or vegetables which have yielded 
 
CYANIN. 7 
 
 them; the more important will be somewhat fully 
 described in the following pages, and others of less com- 
 mercial importance will be found given in the table at the 
 close of the work. 
 
 It is a remarkable fact that the most brilliant and beau- 
 tiful colours, which are observed in those flowers and parts 
 of the plant most exposed to the sun, are the most delicate 
 and the most difficult to isolate. These organs contain so 
 little of the colouring principle, and it is so fugitive, that 
 when an attempt is made to extract it, it disappears alto- 
 gether. Generally, in flowers, the colouring principle is 
 fixed in the epidermis or cellular tissue of the petal, for the 
 fluid obtained by expressing the whole leaves is almost 
 entirely colourless. 
 
 According to Fremy and Cloez, all the colours which are 
 observed in flowers, may be referred to three principles 
 only, namely : — cyanin, a compound which is blue or pink ; 
 xanthin, a compound of a yellow colour, insoluble in water; 
 and xanthein, a yellow compound soluble in water. 
 
 Cyanin is uncrystallisable, soluble in water and alcohol, 
 but insoluble in ether. Acids, or acid salts, immediately 
 change it to a red and alkalis communicate to it a green 
 colour. It is decolourised by reducing agents, but re- 
 gains its colour in contact with oxygen. It may be ex- 
 tracted from the petals of the cornflower, the violet, or the 
 iris, by means of boiling alcohol; the flower becomes 
 decolourised, and the liquid assumes a beautiful blue colour. 
 This solution is evaporated to dryness, and the residue 
 treated with water, which leaves undissolved a fatty and a 
 resinous substance. Neutral acetate of lead is then added 
 to the aqueous solution containing the colouring matter, 
 when a beautiful green precipitate falls, which is washed 
 with water and decomposed by sulphuretted hydrogen. 
 The solution of the colouring matter is separated from the 
 sulphide of lead by filtration, and the liquid carefully 
 
8 DYEIXG AXD CALICO PRINTING. 
 
 evaporated on a water-bath. The residue, after being dis- 
 solved in absolute alcohol and precipitated by ether, yields 
 the cyanin in the form of bluish white flakes. 
 
 Flowers, like roses, peonies, and some dahlias, when 
 treated in a manner similar to that just described, yield a 
 pink compound. A careful study of the properties of this 
 colouring matter shows that it is identical with, or at least 
 similar to the blue one, and that the pink colour is due to 
 certain juices with which it comes in contact, having an 
 acid reaction, whilst the blue is always found where the 
 juices of the flower are quite neutral. 
 
 Xanthin is insoluble in water, alcohol, and ether, and 
 presents the general properties of a resin. It is the mix- 
 ture of this compound with cyanin in the vegetable juices 
 which gives to flowers the various shades of orange, scarlet, 
 and red. Xanthin may be easily prepared from the 
 sunflower. The flowers are treated with boiling absolute 
 alcohol, which dissolves the colouring matter and deposits 
 it on cooling. It is not pure however, being mixed with a 
 certain quantity' of oil, which is removed by a careful 
 saponification and treatment with acid; a mixture of the 
 xanthin and fatty acids is thus thrown down, from which 
 the latter may be dissolved out by cold alcohol, leaving the 
 xanthin in a pure state. 
 
 Certain dahlias contain a substance differing from 
 xanthin by being soluble in water. This colouring matter, 
 which has received the name of xanthein, is soluble in 
 water, alcohol, and ether, but has not been obtained in a 
 crystalline state from any of its solvents. Alkalis com- 
 municate to it a rich brown colour, but the original shade 
 is restored by acids. It has great dyeing power, producing 
 on the various fabrics yellow shades of considerable 
 brilliancy. This substance may be prepared from the 
 petals of yellow dahlias, in a manner similar to that 
 followed in the prepartion of cyanin from blue flowers, 
 
XANTHEIN. 9 
 
 except that sulphuric acid should be employed for decom- 
 posing the lead compound instead of sulphuretted hydro- 
 gen; the residue from the aqueous solution is extracted by 
 alcohol, which dissolves the xanthein, and on evaporation 
 leaves it in a state of purity. 
 
 The yellow colouring matters are entirely distinct from 
 cyanin. We know that blue flowers may become red and 
 even white, when the colour is completely destroyed, but 
 they never become yellow; and, on the other hand, yellow 
 flowers never become blue. It is not unusual to see orange 
 flowers become red, but in this case the xanthin is 
 destroyed and the cyanin is left in the red state, modified 
 by the acid juices of the flower. 
 
 A great number of flowers open white or pink, and 
 become blue on exposure to the air; others, which are 
 colourless in the bud, become yellow when they are full 
 blown, and as they decay assume a brownish tint. In all 
 flowers the colour is deeper at the outside edge than in 
 the centre. 
 
 Although little doubt can exist that the brilliancy and 
 intensity of the colours of flowers is to a great extent 
 dependent on the amount of light they receive, the follow- 
 ing interesting experiment of Persoz shows that the roots 
 of plants have a reducing power, and that some colouring 
 matters can be produced by the process of oxidation in the 
 flower. If some stems of balsams, deprived of their 
 roots, be placed in a solution of sulphate of indigo, the 
 solution is absorbed and the stem is soon dyed blue; but if 
 the plant, with the root attached, is placed in the liquor 
 it continues to live and absorbs the solution, but in a 
 colourless state, and the reducing power of the root may 
 be well seen if the solution is exposed to the air, for it will 
 become colourless or slightly green away from the surface, 
 while the part in contact with the air has the appearance 
 of a blue layer. Although in this experiment the stem 
 
10 DYEING AND CALICO PRINTING. 
 
 remains colourless, the flowers rapidly acquire a blue 
 colour. 
 
 M. Becquerel has recently published an interesting series 
 of papers on the action of electricity on flowers. He tried 
 currents of induction, and also sparks from an electrical 
 machine, so weak as to avoid, as far as possible, the pro- 
 duction of chemical changes. 
 
 On submitting the petals of the Papaver orientalis, which 
 have an intense scarlet colour, to the action of sparks from 
 an electrical machine, he found that the part of the petal 
 nearest to the electrical influence was immediately decolour- 
 ised, and by prolonging the action the entire petal became 
 colourless. On dipping the petal into cold water, the water 
 assumed a violet tint, whilst the petal remained colourless 
 The petals of the iris, acted on in a similar manner, were 
 entirely decolourised, but yielded their colour to water. 
 
 Yellow flowers appeared to undergo little or no change, 
 but if an orange flower, such as a nasturtium, were treated, 
 in a similar manner, he found that it yielded to water its 
 red colouring matter, whilst it retained the yellow one. 
 
 Heat, or exposure to a cold of several degrees below 
 zero produced the same results, for, when the poppy before- 
 mentioned is dipped for a few seconds into boiling 
 water, the red colour becomes slightly purple; and if it is 
 now placed for some time in cold water, the colouring 
 matter is dissolved and the petals become colourless. 
 
 M. Becquerel concludes from these experiments that the 
 walls of the cells of the petals are in all three cases injured, 
 or their organisation so altered that when placed in water 
 it penetrates into the cells, and the soluble red and blue 
 colour is dissolved out, whilst the yellow colouring matter 
 being insoluble and existing in the form of minute 
 granules, is not removed. 
 
 The colouring matters possess, as proximate principles 
 and in the free state, a number of characteristics in 
 
EFFE CT OF HE A T ON COL URS. 1 1 
 
 common. They are solid, inodorous, and generally taste- 
 less. Many may be obtained in regular crystals, as small 
 brilliant needles; some resemble the resins; others are 
 found as plates and scales, or in globular masses. Their 
 colour in the dry state is often very different from that 
 they have when moist or in solution. Thus carthamin 
 when dry has a coppery appearance, but a magnificent 
 dark red colour when moist; and hematoxylin has a 
 pinkish white colour in the dry state ; whilst a cold aqueous 
 solution is yellow, and a hot solution orange-red. 
 
 All the colouring matters are destroyed at a temperature 
 of 300 to 400 F., giving off products analogous to those 
 obtained in the dry distillation of other proximate prin- 
 ciples. Those which contain nitrogen give off ammonia. 
 
 But if instead of heating them quickly, they are sub- 
 mitted to a regulated heat, and the temperature is main- 
 tained at a point lower than that at which decomposition 
 commences, many of them volatilise; some without any 
 alteration, whilst others give a certain amount of empyreu- 
 matic products, which carry over a portion of the sub- 
 stance unaltered, the latter being condensed on the cooler 
 parts of the vessel. By the aid of a current of steam, more 
 or less superheated, they may in many cases be sublimed 
 without any decomposition taking place. 
 
 Those colouring matters which can be distilled, either 
 alone or by the aid of steam, are generally faster than the 
 others, being less easily affected by chemical reagents. 
 
 Direct sunlight acts on colouring matters in a similar 
 manner to heat, but requires more or less time to produce 
 the change. Scarcely any of the colours will bear a pro- 
 longed exposure to strong sunlight, as may be seen in 
 curtains and in those parts of a carpet which are nearest the 
 windows; this effect is also well shown in ladies' dresses, 
 where the inside of the folds retain to a great extent their 
 original brilliancy, whilst the exposed parts are faded. 
 
12 DYEING AND CALICO PRINTING. 
 
 Some colours, safflowcr, for instance, are sensibly altered 
 even after a few hours' exposure. 
 
 This change is not due to light alone, but requires also 
 the presence of oxygen and moisture, as was shown by 
 Chevreul, who placed the colouring matters of safflowcr, 
 annatto, and archil under the influence of direct sunlight 
 in vacuo, without producing any change; they may also be 
 kept for a great length of time in the air, provided light be 
 excluded, or even in perfectly dry oxygen and exposed to 
 light, but as above stated they are soon affected by the 
 combined action of light, air, and moisture. The old pro- 
 cess of grass bleaching is another familiar illustration of 
 this combined action in removing or destroying colouring 
 matters. 
 
 Heat has, to a certain extent, the same action as light. 
 Safflowcr pink becomes of a dirty white colour in an hour, 
 and the red of Brazil wood undergoes the same change in 
 two hours, when heated to a moderate temperature in a 
 current of moist air. The violet of logwood, the orange 
 of turmeric, and the yellow of weld, all become dark, 
 brown, and tarnished, under the same conditions. 
 
 The terms fast and fugitive are used to express the 
 relative action of oxygen on the various colours. 
 
 Those bodies which easily give up all or part of their 
 oxygen, on account of their want of stability, are also 
 destructive to colouring matters. Some of them, however, 
 as bichromate of potash, may be used with advantage in 
 fixing certain colours, and this is particularly the case with 
 those obtained from the red woods. 
 
 None of the colouring matters can resist chlorine, but 
 its action appears to vary very much according as it is in a 
 moist or a dry state. When dry chlorine is passed over a 
 dry colouring principle, in some instances part of the chlo- 
 rine is substituted for some of the hydrogen in the com- 
 pound, whilst another part combines with the hydrogen 
 
ACTION OF CHLORINE ON COLOURS. 13 
 
 so liberated to form hydrochloric acid ; but the reaction is 
 always slow, and the substitution is seldom complete. In 
 the presence of water, however, the decolouration is instanta- 
 neous, and is probably effected by the nascent oxygen 
 which is liberated from the water by the action of the 
 chlorine. 
 
 'The hypochlorites also act on colours, but more slowly 
 than free chlorine, and in this case it is the oxygen con- 
 tained in the compound, and not the chlorine, which is the 
 bleaching agent. Contact with the air (probably on account 
 of the carbonic acid it contains), or the addition of an acid 
 facilitates the action considerably. It is on this account 
 that in bleaching calico the cloth is passed through an acid 
 bath after it comes from the bleaching solution. 
 
 Charcoal is also a very powerful decolourising agent, but 
 acts in a manner altogether different from chlorine, as it 
 does not in general alter the colouring matters, but re- 
 moves them from the liquids holding them in solution. 
 This property it possesses not by a chemical affinity analo- 
 gous to that which determines their union with metallic 
 oxides, but by a physical or molecular attraction, so that 
 in most cases the unaltered colouring matters may be 
 recovered from the charcoal by suitable methods. 
 
 For example, if a weak solution of sulphate of indigo 
 be decolourised by charcoal, the indigo may be removed 
 from the latter by washing it with boiling water, containing 
 in solution a small quantity of carbonate of soda. And 
 by continued washing almost all the indigo may be 
 covered. 
 
 The best charcoal for this purpose is that possessing the 
 greatest purity and which is in the finest state of division. 
 Those charcoals which are hard and lustrous, such as anthra- 
 cite, graphite, or gas coke, are not adapted for removing the 
 colour from liquids ; whilst spongy charcoal, light and dull, 
 such as animal charcoal, or that obtained by heating ani- 
 
i 4 DYEIXG AND CALICO PRINTING. 
 
 mal matters with carbonate of potash, and removing the 
 latter by washing with water, possesses the property in a 
 very high degree. The presence of saline or earthy matters 
 in charcoals, as it increases the amount of surface of car- 
 bon in contact with the liquid, increases also the decolour- 
 ising power, and it is on this account that the animal 
 charcoal, obtained by heating bones, is so much mo're 
 efficacious than that prepared from wood. 
 
 Stenhouse found that if an intimate mixture of one part 
 of coal tar and six of quicklime was ignited out of contact 
 with the air, and when cold treated with hydrochloric acid 
 to remove the lime, a charcoal was left which possessed 
 very energetic decolourising powers; also that if vegetable 
 matters be mixed, before calcination, with phosphate of 
 lime, alumina, or clay, a charcoal may be produced which 
 is nearly equal in decolourising power to bone charcoal or 
 ivory-black. 
 
 Most of the colouring matters are soluble in water, and 
 always more so in hot water than in cold; their solubility 
 appears to increase with their richness in oxygen. Carotin 
 and indigotin, for example, which contain but very little, 
 are altogether insoluble. 
 
 The aqueous solutions alter somewhat rapidly in contact 
 with the air, and lose their colours much more quickly 
 under these circumstances than the moist colouring matters 
 themselves. 
 
 Certain saline matters when dissolved in water prevent 
 the solution of colouring matters. 
 
 Alcohol, ether, wood-spirit, benzene, chloroform, bisul- 
 phide of carbon, glycerin, and the oils and essences 
 generally, dissolve many of the colouring matters freely, 
 and frequently in quantities about inversely proportional to 
 their solubility in water. 
 
 Considering the manner in which they act with the pre- 
 ceding reagents, we may view the colouring matters as 
 
SOLUBILITY OF COLOURING MATTERS. 15 
 
 divided into two classes, the resinoi'd and the extractive. 
 To the first will belong those which are insoluble or only 
 slightly soluble in alcohol, ether, and the oils, such as cur- 
 cumin, carthamin, alizarin, indigotin, &c. ; and to the second, 
 those which are soluble in water. 
 
 Some of those which are insoluble in water, dissolve in 
 that liquid on the addition of acids or alkalis, thus : — 
 alizarin dissolves freely in concentrated sulphuric acid ; 
 santalin and anchusin dissolve in acetic acid; and cartha- 
 min, santalin, and bixin dissolve readily in dilute alkalis. 
 
 By adding hydrochloric acid, or better still, sulphuric 
 acid, to alcohol or ether, most of the colouring matters 
 may readily be obtained in solution. It was with a mix- 
 ture of four parts of sulphuric acid, with one of alcohol, 
 that Persoz obtained the greater number of the colouring 
 principles from the dyestuffs which contained them. 
 
 Only the more stable colouring matters can be dissolved 
 in acids or alkalis without undergoing alteration ; the others 
 undergo a change more or less marked, assuming various 
 shades, which are in some instances characteristic. The 
 colouring matter of flowers already referred to is an 
 example of this, as is also that of the red cabbage. 
 
 The changes produced by acids and alkalis on the 
 litmus used by chemists, are due to an action very different 
 from that produced on flowers, for the former really enters 
 into combination with the agents which act upon it. The 
 litmus cakes of commerce are composed, of a red colouring 
 mater and an alkali; if this compound is placed in con- 
 tact with an acid, it is decomposed and the red colouring 
 matter is liberated; on the addition of an alkali the blue 
 compound is again formed. 
 
 Concentrated acids and alkalis, at an elevated tempera- 
 ture, entirely decompose all colouring principles, even the 
 most stable. Under the influence of alkalis the colours are 
 modified and destroyed, even if air be excluded ; if air be 
 
1 6 DYEING AND CALICO PRINTING. 
 
 present, an absorption of oxygen takes place, and a brown 
 colouring matter is formed. 
 
 None of the colouring matters can resist the action of 
 nitric acid, but nitrosulphuric acid produces the most rapid 
 and completely destructive action. Ammoniacal cochineal, 
 which is unchanged by sulphuric acid, is immediately de- 
 colourised by even a weak solution of nitrosulphuric acid. 
 
 The action of sulphurous acid differs from that of the 
 other acids. It has long been used for bleaching silk, wool, 
 straw, &c, and is also used to remove stains made by fruit 
 on colours, which sulphurous acid does not spoil. Some 
 colours, such as cochineal, are not affected by it; some, such 
 as logwood, are completely destroyed, whilst others are 
 simply bleached, and on being exposed to the air, gradually 
 reassume their original tint. 
 
 Sulphurous acid acts as a bleaching agent by combining 
 with the colours, and on the combination being destroyed, the 
 original colour is restored. As examples of this: — if a red 
 rose be placed in a vessel containing sulphurous acid, it 
 becomes white in a few minutes ; but if it be then dipped 
 in a weak solution of sulphuric acid, it immediately recovers 
 its natural colour, as the latter acid displaces the former. If 
 the bleached rose be placed in chlorine the colour is also 
 restored, for this element converts the sulphurous acid into 
 sulphuric acid. Violets, when placed in an atmosphere of 
 sulphurous acid, are bleached, but on exposing them to 
 ammoniacal vapours they become green, the ammonia not 
 only neutralising the acid, but itself acting on the cyanin 
 and altering its colour. 
 
 The anhydrous metallic oxides do not act on colouring 
 matters, but the hydrated oxides combine with them, 
 forming insoluble compounds called lakes. These may be 
 considered as salts, in which the colouring matters play the 
 part of acids, and which can be displaced by stronger acids, 
 as will be seen further on. This affinity of colouring 
 
MORDANTS. 
 
 17 
 
 matters for metallic oxides has been taken advantage of 
 for fixing many colours on fabrics. 
 
 The salts, metallic or alkaline, act on the colouring 
 matters sometimes by their acid, sometimes by their base, 
 but more frequently by the latter. In the first case they 
 brighten or change the colour, whilst in the second their 
 oxides combine with the colouring principles, forming 
 insoluble precipitates. If a solution of acetate of lead or 
 chloride of tin be poured into a solution of hematoxylin, 
 bresilin, or santalin, precipitates of various colours are pro- 
 duced, which are really lakes or compounds of the colouring 
 matters with the base, whilst the supernatant liquors retain 
 the liberated acid. 
 
 In several cases the presence of tissues greatly facilitates 
 this decomposition. In this case the lake is deposited in 
 the tissue and fixed there, so that, to a certain extent, a dyed 
 fabric may be considered as a ternary compound of tissue, 
 metallic oxide, and colouring principle. This is the funda- 
 mental principle of the theory of mordants, a name given 
 to salts and other substances by means of which we are 
 able to fix colouring matters which of themselves have no 
 affinity for the fabric. It is, however, rare for a salt to act 
 as a mordant without undergoing decomposition. 
 
 Mr. John Thorn was the first to observe that there is also 
 an elective affinity of the bases for the various colouring 
 matters, that is, that the bases have a stronger attraction for 
 some colouring matters than for others. An example of 
 this may be seen in alumina, which has a stronger attraction 
 for the principle of madder than for that of logwood, and 
 a greater affinity for the latter than for that of quercitron. 
 When a piece of cloth impregnated with alumina is 
 immersed in a decoction of quercitron bark, it acquires a 
 fast yellow hue; but, if it is afterwards well washed, and 
 then kept for some time in a hot solution of logwood, the 
 alumina parts with the colour of the quercitron to combine 
 c 
 
1 8 DYEING AND CALICO PRINTING. 
 
 with that of the logwood, and the cloth changes from 
 yellow to purple. If it be now digested for a few hours 
 with a hot infusion of madder, the colouring principle of 
 logwood is turned out, and the alumina unites with that of 
 the madder; the cloth is now found to be red instead of 
 purple. The amount of alumina on the fibre does not 
 appear to be sensibly altered by these substitutions. 
 
 Certain salts produce on colouring matters oxidising or 
 even decolourising effects. In the latter instance it is the 
 acids which act, as is the case with the hypochlorites, the 
 chlorates, and the bichromates. In the former case they 
 usually act by their bases; for example, chloride of am- 
 monium mixed with salts of copper forms double salts, 
 which have the property of oxidising the colouring matters 
 and yielding oxide of copper, which, fixing itself along 
 with them in the fibre of the cotton fabrics, gives greater 
 fastness to the colour. The chloride of ammonium cannot 
 in this case be replaced by any other chloride. According 
 to Kcechlin and Plessy this process is especially applicable 
 to the colouring matters of logwood, lima-wood, and 
 catechu. 
 
 The salts of gold, silver, and mercury, are reduced by 
 the colouring matters, which combine with the oxygen and 
 are thus altered or destroyed. 
 
 The colouring matters combine with the various tissues 
 forming compounds more or less fast. In general they 
 show a greater affinity for animal substances, such as wool 
 and silk, than for vegetable fibres, such as cotton, hemp, and 
 flax, and of these three they have more affinity for cotton 
 than for the other two. 
 
 Of the known colouring matters some precipitate imme- 
 diately upon tissues with which their solutions are in con- 
 tact, while others cannot adhere to it in a durable manner 
 without the intervention of a second substance which has 
 a more energetic attraction for the colour than the tissue 
 
FAST AND LOOSE COLOURS. 
 
 19 
 
 itself has. To the first class belong indigotin, curcumin, 
 orcein, and carthamin. Those of the second class are fixed 
 by taking advantage of the affinity which certain metallic 
 oxides possess both for the colouring matter and for the 
 fibre. 
 
 The name of 'fast' colours is given to those which resist 
 the action of light, air, water, alcohol, dilute acids and 
 alkalis, and of weak hypochlorites and soap solution. As 
 examples of these may be mentioned the colours derived 
 from madder, indigo, quercitron, cochineal, catechu and 
 gallnuts, and salts of iron. 
 
 The term 'loose' colours is applied to those which are 
 quickly destroyed by light and air, and which, notwith- 
 standing their insolubility in water, are removed or altered 
 by dilute acids or alkalis, and by weak hypochlorite or soap 
 solutions. Among these may be mentioned the colours 
 derived from the redwoods, logwood, Persian and Avignon 
 berries, turmeric, annatto, and safflower. 
 
 These divisions, however, must be regarded as somewhat 
 arbitrary, and merely useful as a general classification, since 
 we find that in the first class some are much faster than others, 
 whilst in the second some are much more fugitive. Besides 
 this difference, the same colouring principle may give fast 
 colours with some mordants, and loose with others. Even 
 with the same colour and with the same mordant this differ- 
 ence may be observed when the way is varied in which the 
 colour is produced or applied to the fabric. As an illustra- 
 tion of this, we find that when the colouring matter of 
 logwood has been applied to a tissue by means of a salt 
 of alumina, the purple thus obtained is not washed away 
 by water, but is rapidly altered by exposure to the atmos- 
 phere; when, on the contrary, it has been applied as a 
 pigment, by means of a salt of tin, although it resists the 
 action of the atmosphere, it is almost entirely removed by 
 boiling water; whilst, if it be treated with bichromate of 
 
20 DYEING AND CALICO PRINTING. 
 
 potash, it becomes fit to resist both water and atmospheric 
 influences. Again, if one piece of mordanted cloth is dyed 
 in a bath containing Alsatian madder and water only, whilst 
 a second piece is dyed in a bath of the same madder con- 
 taining also a little chalk, or in one of Avignon madder, 
 we find such differences as would lead us to imagine that they 
 are altogether different dyestuffs ; or, by placing together a 
 steam-pink and a pigment pink, it appears impossible to 
 believe that they contain the same colouring principle, the 
 steam-pink resisting every agent that does not act on 
 madder reds, whilst the pigment pink is much more easily 
 altered by exposure to the atmosphere and is readily dis- 
 coloured by soap. 
 
 Chevreul, by a series of interesting experiments, proved 
 that colours vary considerably in their power of resisting 
 heat in vacuo, and that some, which are very fugitive under 
 the influence of air and light, or of soap, remain fast, whilst 
 others resisting these agents are much injured by heat. 
 
 Turmeric, which fades so rapidly in the air, may be 
 exposed on cotton and silk to a temperature of '320 F. 
 in vacuo, without any alteration. Brazil wood, cochineal, 
 quercitron, weld, and orchil, fixed by alum and tartar on 
 cotton or silk, undergo little or no change under similar 
 circumstances. Logwood, fixed by the same process, under- 
 goes a remarkable modification, the blue purple becoming 
 a red purple, as if it had been treated with an acid. Log- 
 wood, Brazil wood, and cochineal, fixed by a tin mordant, 
 have a greater tendency to alter than when fixed by an 
 alumina mordant. 
 
 The nature of the fabric also may have an influence on 
 the fastness of a colour under these circumstances, as it has 
 also when exposed to light. For instance, safflower may be 
 exposed to 320 F. in a vacuum, without injury when 
 dyed on silk, but on wool or cotton it is much altered. 
 Annatto similarly treated is less fast on silk than on cotton. 
 
A CTION OF HE A T ON COL URS. 2 1 
 
 The influence of the fabric is shown also by the joint 
 action of air and heat. Indigo, thus treated, is more fixed 
 on silk than on cotton. Sulphindigotic acid at 320 F. 
 is only slightly altered on silk and cotton, but much more 
 so on wool, and steam has a tendency to turn it green, 
 especially on wool and silk ; and on wool dyed in the vat, 
 the colour is weakened at 320 to 350 F., and assumes a 
 greenish hue. 
 
 Indigotin, sulphate of indigo, and also Prussian blue, 
 although stable on cotton, are not so on wool; and, for the 
 same reason, namely, a certain reducing action of the 
 fabric. 
 
 All Chevreul's experiments on these interesting points, 
 show that cotton exerts very litle reducing power on 
 colouring matters, whilst silk, and especially wool, possess 
 it to a considerable extent. 
 
 It may be mentioned also, in passing, that this chemist 
 proved that even so fast a colour as Prussian blue could be 
 entirely decomposed by light, for he found that a piece of 
 woollen dyed with Prussian blue when placed in a vacuum 
 and exposed to the direct rays of the sun, lost all its blue 
 colour, and became of a slightly yellowish tint. On ex- 
 posure to the air in a dark place it resumed its original 
 colour. 
 
CHAPTER II. 
 MADDER. 
 
 This well-known tinctorial substance may still be con- 
 sidered as the most important of all the dyestuffs employed 
 by calico printers, owing to the brilliancy and variety of 
 shade and colour that can be obtained from it ; one dyeing 
 operation being sufficient to produce pinks, reds, purples, 
 violets, puce, and black. Besides this they are permanent 
 under the action of light and soap, and the wear and tear 
 to which they are exposed during the processes of dyeing 
 and clearing. 
 
 The employment of madder-root as a dye dates from the 
 most ancient times, as some of the fabrics used by the 
 Egyptians for enveloping their mummies are dyed with it. 
 The Greeks and Romans were also acquainted with madder 
 under the names of Erythrodanon and Rubia, and their 
 modes of fixing it on cotton fabrics were the same as those 
 now employed, namely, aluminous salts for producing reds, 
 and salts of iron for purples and blacks. Although it is 
 probable that it has been cultivated in Italy ever since that 
 time, yet it was only introduced into Holland in the six- 
 teenth century and into Alsace in the seventeenth. It is 
 curious to remark that its introduction into Avignon in 1762 
 was due to an Armenian who brought the plant with him 
 from the East. 
 
 The plant which produces madder is an herbaceous per- 
 ennial called Rubia tinctorum. It bears a yellow flower, 
 
MADDER. 
 
 23 
 
 and its fruit is a dark red berry. The red colouring matter 
 exists almost entirely in the cortical part of the root, little 
 or none being found either in the epidermis or in the 
 ligneous or centre part of the root. Decaisne and Schwartz 
 have stated that there is only one colouring matter in the 
 root, that it is yellow, and that it becomes red under the 
 oxidising influence of the atmosphere. These results have 
 since been confirmed by Grelley, Gerber, and Dolfus. (The 
 researches of Schunck, which will be referred to further on, 
 show that the colouring matter does not exist in the plant 
 in a free state, but in combination with a sugar; to this 
 glucoside he gave the name of rubian.) 
 
 The oxidising process goes on to a certain extent, in the 
 roots of the plant when they are allowed to remain for 
 several years in the ground, especially in chalk formations. 
 In France the roots are allowed to remain in the ground 
 two or three years ; in Turkey and the East, from five to 
 seven. In the latter countries and in Naples they are dried 
 in the open air, but in Holland and France stoves are em- 
 ployed for this purpose. Naples and Turkey madders are 
 imported in the root, and are known in commerce as Naples 
 and Turkey roots, whilst those from France and Holland 
 are ground and sold under the name of French and Dutch 
 madder. 
 
 The importance of this trade on the continent may be 
 judged of from the fact that in one of the departments of 
 France, Vaucluse, there are about fifty mills turned by water 
 power, which grind eighty millions of lbs. per annum. The 
 quantity grown in this department alone represents a value 
 of about a million sterling. 
 
 One hundred parts of fresh root, yield on perfect desicca- 
 tion, twenty parts of the dried substance, and the roots, as 
 imported, always contain from 16 to 18 per cent, of water; 
 the fresh roots, therefore give about 24 or 25 per cent, of 
 commercial madder. Dutch and Alsatian madder, after 
 
24 DYE1XG AXD CALICO PRINTING. 
 
 being ground, is stored in large casks and kept for two or 
 three years, when the colouring matter is developed, and its 
 tinctorial power much increased ; if kept five or six years, 
 however, further changes ensue, and its value seriously 
 decreases. French Avignon madder, on the contrary, can be 
 employed at once, although the quality is much improved by 
 keeping it for one or two years. The best Avignon madders 
 are grown on lime formations. The roots which have a red 
 colour are called "palus," and those that are pink "rosees;" 
 the former being considered the finer. The values of these 
 madders are in proportion to the fineness of their powders, 
 the finest powder containing the most colouring matter. 
 One hundred parts of dried madder root consist of — 
 
 Matter soluble in cold water 55 parts. 
 
 „ soluble in boiling water, and con- 
 taining the greater part of the 
 
 colouring-giving principles 3 „ 
 
 „ soluble in Alcohol 1.5 „ 
 
 Fibrous matter 40.5 „ 
 
 The nature of the chemical changes, which occur in 
 madder during the time it is stored, and which so much 
 improve its commercial value, was -entirely unknown until 
 the year 185 1, when the elaborate and interesting researches 
 of Dr. E. Schunck were published. This chemist succeeded 
 in isolating a peculiar ferment called erythrozym, which 
 possesses the property of decomposing a substance existing 
 in the root, and called by him rubian. Rubian may be 
 considered as a glucoside (the name given to compounds 
 of sugar with other organic principles), which is decomposed 
 by the erythrozym into alizarin and a peculiar sugar. 
 
 The following is a slight sketch of our present knowledge 
 of the colouring matters which have been obtained from 
 the madder root. Robiquet and Collin, in 1824, were the 
 first to isolate any distinct chemical compound from 
 madder; this they did by heating it with strong sulphuric 
 
COLOURING PRINCIPLES IN MADDER. 25 
 
 acid, whereby it was converted into a black mass, the so- 
 called charbon-de-garance, which on being carefully heated, 
 yielded a sublimate of beautiful orange-coloured crystals. 
 To this substance they gave the name of alizarin, and in 
 1828 the same chemists isolated purpurin, another colour- 
 giving principle. About the same time Kuhlmann extracted 
 a bitter yellow compound which he called xanthin. 
 
 Although between this date and 185 1 many chemists 
 attempted to discover the nature of the colouring principles 
 in madder, no accurate information was attained until the 
 publication of Schunck's series of elaborate papers, which 
 threw quite a new light on the subject. 
 
 The experiment by which he proved that there is no free 
 colouring matter in fresh madder roots, and that its pro- 
 duction is entirely due to the action of a ferment, is as 
 follows : — 
 
 Some madder roots having been taken out of the ground, 
 and cut small without being dried, were found to produce 
 colours when used for dyeing in the ordinary manner. But 
 on" treating the roots, after being cut into pieces as quickly 
 as possible, with boiling alcohol, a yellow extract was 
 obtained, which contained rubian, but which, even after all 
 the alcohol had been driven away, was found incapable of 
 imparting to mordants any but the faintest shades of colour; 
 whilst the portion of the root left undissolved by alcohol, 
 on being subjected to the same test, imparted to the cloth no 
 more colour than the extract. It was evident therefore 
 that the alcohol had effected a separation between the 
 colour-producing body and the agent, which, under ordinary 
 circumstances, is destined to effect its transformation into 
 colouring matter. 
 
 To this special ferment, which is insoluble in alcohol, he 
 gave the name of erytkrozym. The value of the discovery 
 that colouring matters existed in plants in the state 
 of glucosides, and that they were unfolded by special fer- 
 
 D. H. HILL LIBRARY 
 
 North Carolina State College 
 
DYEIXG AXD CALICO PRIXTIXG. 
 
 ments, cannot be too highly estimated ; an idea of its import- 
 ance may be formed from the fact that it has enabled 
 Schunck to explain the production of indigo from the plant 
 which yields it ; that it has lead to the isolation of several 
 other colouring principles ; and that it throws much light 
 on the chemical changes which take place in madder roots 
 from the time they are gathered to the time they are used. 
 There is no doubt that the changes taking place while the 
 madder is stored (the time varying as before stated from two 
 to six years according to the country in which the madder 
 is grown) are due to the action of the erythrozym, which 
 gradually resolves the rubian into sugar and alizarin. 
 Whether there are various other glucosides which are 
 decomposed by the ferment giving rise to purpurin and the 
 other colouring matters, or whether all these are formed by 
 gradual oxidation from one colourless substance which is 
 liberated by the action of the ferment, is a point not yet 
 satisfactorily explained. The researches of Emile Kopp, 
 Schiitzenberger, and Bolley support the latter view, whilst 
 Schunck appears to be in favour of the former. 
 
 To prepare erythrozym, Schunck places a quantity of 
 madder in a piece of calico, and for every pound of the root 
 pours upon it four quarts of distilled water at ioo' F. To 
 the extract so obtained, an equal volume of alcohol is 
 immediately added, which causes the precipitation of dark 
 reddish-brown flocks; these after being collected on a filter 
 and washed with alcohol until the filtrate is colourless, 
 leave a mass which has the same feel as casein ; when dried 
 it coheres into hard lumps which are almost black. 
 
 Erythrozym becomes insoluble in water after it has been 
 once precipitated by alcohol, and it is an interesting fact 
 that its power of producing fermentation appears to be 
 restricted to rubian, for the glucosides from other plants, 
 such for example as those of indigo, do not undergo any 
 chansre when submitted to its action. 
 
ERYTHROZYM. 27 
 
 Erythrozym possesses in an eminent degree the power of 
 effecting the decomposition of rubian. If a mixture of the 
 two substances be left to stand at ordinary temperatures, a 
 complete change takes place in the course of a few hours. 
 The liquid is converted into a jelly of a light-brown colour, 
 perfectly tasteless, and insoluble in cold water. 
 
 The aqueous solution of erythrozym is coagulated when 
 heated to its boiling point. This important fact ought to 
 warn madder dyers to avoid carrying their dyebecks too 
 rapidly to the boil; and it appears highly probable that if 
 they were to moisten the madder with tepid water, and 
 leave it to stand for several hours, or even days at a 
 moderate temperature, previous to its being employed in 
 the dyebecks, they would materially increase its dyeing 
 powers. Certain salts, among which may be mentioned 
 common salt, also coagulate this ferment. 
 
 Schunck found erythrozym to be a compound of lime 
 with a nitrogenous substance, and that if the lime were 
 removed by means of an acid, the erythrozym lost its power 
 of inducing fermentation, which moreover was not restored 
 on the addition of fresh lime to replace that which had been 
 removed. This observation would naturally suggest that a 
 little chalk ought to be added to the dyebeck, in using 
 madders or roots which have been either badly stored or 
 stored too long, and in which an alcoholic, acetic, or lactic 
 fermentation had taken place and so made them acid ; it 
 also explains why it is found so advantageous to add chalk 
 to the dyebeck when using certain classes of madder, such 
 as Turkey roots, or Dutch or Alsace madder, for the chalk 
 prevents the removal of the lime from the ferment which 
 would then be renderd inert. 
 
 According to Schunck, the elementary composition of 
 erythrozym is C 56 H 34 N 2 O 40 +4CaO. 
 
 It will now be advisable to give a short account of the 
 properties and characteristics of the most important prin- 
 
28 D YEING AND CALICO PRINTING. 
 
 ciple discovered by Schunck, viz., rubian, and then to 
 describe the action of erythrozym upon it. 
 
 To obtain rubian, Avignon madder is placed on a piece 
 of calico stretched on a wooden frame, and boiling water 
 poured over it in the proportion of four quarts to each 
 pound of madder. To the yellowish-brown liquor thus 
 obtained, whilst still hot, animal charcoal is added in the 
 proportion of one ounce for every pound of dyestuff. The 
 whole is then well stirred and allowed to settle. The char- 
 coal after being collected on a filter is washed with cold 
 water until all the chloregenin is removed, which is the case 
 when the percolating liquid on being mixed with hydro- 
 chloric acid and boiled, no longer acquires a green colour. 
 The charcoal is then boiled with successive quantities of 
 alcohol as long as the liquid continues to acquire a yellow 
 tint, and the solution is evaporated. To get rubian quite free 
 from chlorogenin, Schunck advises the use of charcoal which 
 has previously been used two or three times for a similar 
 operation. The sulphides of lead and tin possess the same 
 property at the time of their formation, but the charcoal 
 process is the most convenient and economical. 
 
 Rubian is a hard, brittle, and shining substance, similar 
 in appearance to gum. It is soluble in water and still more 
 so in alcohol, but insoluble in ether, which precipitates it 
 from its alcholic solution. Its solutions have an intensely 
 bitter taste. It gives no precipitates either with mineral or 
 organic acids, with alkalies, or with salts of alumina or 
 iron, &c. 
 
 The above facts threw quite a new light on the substance 
 xauthin, discovered, as already stated, by Kuhlmann. He 
 obtained it by acting on madder with boiling alcohol, 
 evaporating the extract to dryness, and treating the resi- 
 due with water. It was further purified by converting it 
 into a lead compound and subsequently decomposing it 
 with dilute sulphuric acid. The substance was thus ob- 
 
R UBIAN.—XANTHIN. 
 
 29 
 
 tained as a viscid mass of a bright orange hue, soluble in 
 water, and having a bitter taste. It was proved by 
 Schunck to be a mixture of rubian and chlorogenin, for by- 
 treating an aqueous solution of xanthin with animal char- 
 coal, he succeeded in separating the rubian from the 
 chlorogenin. It was formerly supposed by chemists that 
 the injurious action of xanthin was due to its becoming 
 oxidised under the influence of the heat of the dyebeck 
 and the oxygen of the air into a brown substance, which, 
 fixing itself on the cloth, soiled the whites and spoiled the 
 colour; now, however, it is evident that this is caused 
 solely by the chlorogenin which it contained. Rochleder 
 has given this latter compound the name of rubichloric 
 acid. 
 
 In October, 1848, Mr. Higgin, of Manchester, published 
 a paper in the Philosophical Magazine, in which he stated 
 that xanthin could be recognised by its yellow colour, and 
 the bitter taste of its aqueous solution, which he considered 
 as characteristics; and that when the extract of madder 
 was left at a temperature of 130 F. this compound gradu- 
 ally disappeared, and a gelatinous or floculent substance 
 was produced, which possessed all the tinctorial power 
 belonging to an infusion of madder. He concluded from 
 this that the xanthin was converted into alizarin during - the 
 process. Schunck states that these researches gave him 
 the clue to unravel this intricate subject, so that he was 
 ultimately enabled to offer an explanation of the phe- 
 nomena which take place during the fermentation of 
 madder. 
 
 The following, taken almost verbatim from a paper read 
 by Dr. Schunck before the Chemical Society, in the year 
 i860, gives a clear resume of his researches on the actions 
 of erythrozym, acids, and alkalis on rubian and also of 
 the products of its decomposition. 
 
 At first sight the change which rubian undergoes, when 
 
30 DYEING AND CALICO PRINTING. 
 
 decomposed by means either of acids, alkalis, or ferments, 
 would seem to be simple enough. It might be supposed 
 to consist in a splitting up of its complex molecule into 
 alizarin and sugar, and to resemble many analogous pro- 
 cesses with which we are acquainted; the result being the 
 formation of sugar and another body, the two together 
 having originally formed a conjugate compound; this, 
 however, is not the case, for the products of decomposition 
 never consist of alizarin and sugar alone. The part in- 
 soluble in cold water contains in all cases, besides alizarin, 
 two resinous bodies, one, rubiretin, easily soluble in alcohol ; 
 the other, vcrantin, less soluble in that liquid. These 
 bodies, although resembling resins in some respects, must be 
 classed as colouring matters, since their colour seems to be 
 inherent and not a merely accidental property. But in addi- 
 tion to these, there is uniformly found accompanying the 
 alizarin, a third body belonging, as far as general appear- 
 ance and properties are concerned, to the same class of 
 substances as rubiacin. This third body is, however, in 
 each case quite distinct. When acids have been em- 
 ployed for the decomposition of rubian, this third body, 
 which is called rubianin, is found to have the following 
 properties : — It is tolerably soluble in boiling water, and 
 crystallises in lemon-yellow silky needles ; it is decomposed 
 on being heated, but resists the action of nitric and con- 
 centrated sulphuric acids. When alkalies are used instead 
 of acids, rubianin is replaced by rubiadin, which is a body 
 crystallising in beautiful golden-yellow scales, insoluble in 
 water but soluble in alcohol, and is completely volatilised 
 when heated. But when rubian is decomposed by fermen- 
 tation, it yields neither of these two, but in their place 
 rubiafin, a substance resembling rubiadin in most of its 
 properties, but easily distinguished from it by passing into 
 rubiacic acid when treated with perchloride of iron. This 
 substance is usually accompanied by another of similar 
 
DE COMPOSITION OF R UBIAN. 3 1 
 
 properties of which it is difficult to say whether it must be 
 considered as distinct from the others, since it has not been 
 obtained in a state of purity, — it is called rublagin. Now 
 all these bodies which accompany alizarin make their 
 appearance so invariably on the occasions named, that their 
 appearance cannot be considered accidental. Let us see, 
 therefore, how their simultaneous formation from rubian is 
 to be explained. The formula assumed for rubian is 
 C 28 H 34 15 . Hence it follows that rubian is converted 
 into alizarin simply by the loss of seven molecules of water. 
 C 28 H S4 Q 16 = 2C 14 H 10 O 4 + ;OH 2 . 
 
 Rubian. Alizarin. * 
 
 The formation of verantin and rubriretin, is due to another 
 kind of decomposion. The formula of these two bodies 
 being C 14 H 10 O 5 and C 14 H 12 4 respectively, it will be 
 seen that by adding the two together, we obtain one equiva- 
 lent of rubian minus six molecules of water. The compo- 
 sition of the class of bodies to which rubianin belongs is 
 rather doubtful. It is probable that the formula of rubianin 
 is C 22 H 24 9 . If so, it is formed from rubian by the separa- 
 tion from the latter of one equivalent of grape-sugar. 
 Rubiafin, however, being easily convertible into rubiacic 
 acid, must contain sixteen equivalents of carbon, and its 
 formula is therefore probably C 32 H 26 9 , that of rubiadin 
 being the same. 
 
 It appears from this that rubian undergoes not one, but 
 three different processes of decomposition, when acted on 
 by acids, alkalies, or ferments ; that the formation of sugar 
 is connected, not with that of alizarin but with that of 
 rubianin and its allies, and that in fact there is no reason 
 
 * Schunck believed the formula of alizarin to be C 14 H 10 O 4 ; it has since 
 been proved, however, that it is C 14 H s 4 , so that either the decomposition 
 takes place in a manner different to that represented, or the formula assigned 
 to rubian is incorrect ; the latter supposition is very probable, as it is amorphous 
 and consequently its physical properties are no guarantee for its purity. The 
 same remark applies to the other non-crystalline products obtained from 
 madder. — Eds. 
 
32 DYEING AND CALICO PRINTING. 
 
 why one of these processes should not take place to the 
 exclusion of the others; for instance, rubian might be so 
 decomposed as to yield alizarin alone without any of the 
 accompanying bodies, which, in practice, are not only a 
 source of loss, but are actually prejudicial. 
 
 Although in the foregoing quotation Dr. Schunck con- 
 siders that rubian is decomposed by erythrozym into 
 alizarin and water, simply; yet more recent researches have 
 induced him to believe that in part at least there is a 
 decomposition into alizarin and sugar. 
 
 When a solution of rubian is boiled with a considerable 
 quantity of sulphuric acid for some time, and is then 
 allowed to cool, it deposits a large quantity of orange 
 flocks, which, when washed with water until all traces of 
 acid are removed, are found to consist of four different 
 substances, alizarin, verantin, rubiretin, and rubianin. 
 
 Alizarin is easily separated from the other substances: 
 the flocks are dissolved in alcohol, and hydrate of alumina 
 added, which combines with the alizarin. The lake is 
 thrown on a filter and washed, and then treated with 
 carbonate of potash or soda until all the alizarin is dis- 
 solved. On the addition of an acid to the solution the 
 alizarin is thrown down and is collected on a filter. It is 
 then dissolved in alcohol, from which it crystallises as dark 
 yellow crystals without any tinge of brown or red. It 
 differs from the alizarin obtained by sublimation, which 
 will be described further on, by containing three molecules 
 of water. 
 
 Verantin. — On treating the above-mentioned alcoholic 
 solution of the orange flocks with a solution of neutral 
 acetate of copper, verantin is precipitated together with 
 oxide of copper, from which the oxide may be removed 
 by acids. 
 
 The verantin so obtained is a reddish-brown powder of 
 a resinous nature which when heated in a test tube gives a 
 
RUBIANIN.— RUBIACIN. 33 
 
 small quantity of an oily substance without any trace of 
 crystals. It does not communicate any colour to mordanted 
 cloth, and therefore cannot be considered as one of the 
 colour-giving principles of madder. 
 
 Rubiretin was obtained by Schunck as a brown, opaque, 
 resinous mass, brittle when cold, but becoming soft and 
 almost melting in boiling water. It communicates to 
 alcohol a dark yellow colour, and dissolves in alkalis, 
 forming a brownish-red solution, from which it is precipi- 
 tated on the addition of an acid. It has no dyeing 
 powers. 
 
 The two last-named substances were found by Schunck 
 to exist in garancin, and in his opinion they are removed 
 or modified under the influence of high-pressure steam 
 during the transformation of garancin into 'commercial 
 alizarin.' 
 
 Rubianin. — When acids have been employed to decom- 
 pose rubian, a fourth body, rubianin, is obtained; when 
 alkalis have been used the substance produced is rubiadin, 
 and when fermentation by erythrozym has taken place it 
 is rubiafin. All these bodies are soluble in water, from 
 which they crystallise in well-defined yellow needles. 
 
 In 1847, Dr. Schunck obtained directly from madder two 
 interesting substances, which he named rubiacin and 
 rubiacic acid, the former being identical with the madder 
 orange discovered by Runge. 
 
 The best method of preparing rubiacic acid is as follows. 
 The waste liquor from the dyebeck is strained through a 
 cloth, and hydrochloric acid added. A brown flocculent 
 precipitate is thrown down, which is collected on a calico 
 filter and treated with pernitrate of iron until nothing more 
 is dissolved. After filtration hydrochloric acid is added, 
 which throws down a yellow precipitate. This precipitate 
 is dissolved in boiling carbonate of potash, and on cooling 
 yields crystals of rubiate of potash. On the addition of 
 D 
 
34 DYEING AND CALICO PRINTING. 
 
 a strong acid to the solution, the rubiacic acid is precipi- 
 tated as a bright lemon-yellow coloured powder. Its 
 formula is C 1C H 8 8 . It cannot be obtained in a crystal- 
 line form. It is only slightly soluble in boiling alcohol, is 
 soluble without decomposition in cold strong sulphuric acid, 
 but is decomposed by strong nitric acid. Its characteristic 
 property is its solubility in perchloride of iron, with a red- 
 dish-brown colouration. It is precipitated in yellow flocks 
 from this solution by the addition of an acid. The potas- 
 sium salt forms beautiful well-defined crystals of a light 
 brick-red colour. 
 
 ■ If a current of sulphuretted hydrogen be passed through 
 a solution of rubiacic acid, oxygen is removed, and the acid 
 is converted into rubiacin, to which Schunck has assigned 
 the formula C 16 H 10 O 5 . On adding chloride of barium to 
 the sulphuretted hydrogen liquor, a dark purple precipitate 
 is produced, which after being thoroughly washed with 
 water and treated with hydrochloric acid yields rubiacin. 
 By crystallization from boiling alcohol this substance may 
 be obtained in beautiful yellow crystalline needles and 
 plates, having a high lustre. 
 
 It is only slightly soluble in water but very soluble in 
 alcohol, and also in acetic and sulphuric acids, from which 
 it is reprecipitated without change on the addition of water. 
 It is very interesting to observe that rubiacin absorbs 
 oxygen from persalts of iron, being converted into rubiacic 
 acid, whilst it is not so completely oxidised by nitric acid. 
 
 Like all this class of substances it yields a blood-red 
 solution with potassium carbonate, and a dark brown-red 
 with feric salts. With caustic alkalis it gives a reddish 
 purple solution, from which it is precipitated by acids. It 
 only produces a dirty brown colour on mordanted cloth. 
 
 Schunck states that none of these substances, except 
 alizarin, contribute to the production of fast colours during 
 the process of madder dyeing; and, moreover, that they are 
 
SUGAR IN MADDER. 35 
 
 very injurious to the strength and beauty of the colours pro- 
 duced from the alizarin. 
 
 Sugar. — This was obtained from rubian by completely 
 decomposing it with dilute acid. It is a yellow syrup, 
 having no tendency to crystallise.* Heated at 21 2° F. it 
 loses a portion of its water, and becomes brittle and capable 
 of pulverization. By the action of nitric acid it is slowly 
 converted into oxalic acid. It is not precipitated from its 
 aqueous solution by any metallic salt, not even by sub- 
 acetate of lead. Like grape sugar it becomes brown when 
 boiled with an alkali, and yields alcohol and carbonic 
 acid by fermentation with yeast. It lias the same compd- 
 sition as grape sugar. 
 
 For the purpose of convenient reference, a very complete 
 and elaborate table, drawn up by Dr. Schunck, is inserted at 
 the end of the book, in which he gives the principal colour- 
 ing matters studied by him, with their formulae and 
 properties.-f" 
 
 Rochleder, several years ago,! published some interesting 
 researches, in which he states that he succeeded in obtain- 
 ing a crystallised glucoside of alizarin, to which he gave the 
 name of ruberythric acid. C 20 H 22 O u . When quite pure 
 it crystallises in silky prisms, only slightly soluble in cold 
 water, but very soluble in hot. It is soluble also in alcohol 
 and ether, and on being boiled with dilute mineral acids 
 it is converted into alizarin and sugar. 
 
 C 20 H 22 O 11= rC 14 H 8 O 4 + C 6 H 12 O 6 + OH 2 . 
 
 Ruberythic acid. Alizarin. Sugar. 
 
 Although admitting that Rochleder has obtained this 
 
 * Cane sugar appears to e.tist in madder as such : on one occasion a deposition 
 of hard crystals of sugar was observed in an alcoholic extract of madder which 
 had been kept for some time. — C.E.G. 
 
 + For complete details the reader is referred to Schunck's report to the British 
 Association for the Advancement of Science, 1847 anc l 1848, and to the Philo- 
 sophical Transactions of the Royal Society, 185 1, 1852, 1S53. 
 
 X Jour, fiir Prakt. Chem. Iv. 385 and lvi. 85. 
 
36 DYEING AND CALICO PRINTING. 
 
 glucoside of alizarin, Schunck maintains* that it does not 
 exist as such either in madder or in rubian, but is a product 
 of the oxidation of rubian under the influence of alkalis. 
 He prefers to give it the name of rubianic acid. 
 
 Rochleder has recently found-f- that, besides alizarin and 
 purpurin, garancin contains small quantities of four yellow 
 crystalline substances. The one which is the most abun- 
 dant, and which he calls isalizarin, has the same composi- 
 tion as alizarin, C 14 H 8 4 . It differs from that compound, 
 however, by the red colour of its alkaline solutions, which 
 is intermediate between that of alizarin and that of purpu- 
 rin, and it gives no colour on mordanted cloth. The 
 second substance, kydralizarin, C 28 H 18 8 , has a paler hue 
 than isalizarin, and communicates to a hot solution of per- 
 chloride of iron a brown colour, from which, on cooling, it 
 separates in the form of yellow flocks. The other two 
 bodies, which occur in very small quantity, have the formula 
 C 15 H 10 O 4 and C 29 H 20 O 8 , but no name has at present 
 been assigned to them. 
 
 According to Schiitzenberger, madder contains rubian, 
 ruberythric acid, alizarin, purpurin, an orange substance 
 pseudopurpurin, and purpuroxanthin. 
 
 The two first-mentioned have been already described, 
 and alizarin and purpurin are so important that they will 
 be noticed at length further on. The three other colouring 
 matters, discovered by Schiitzenberger in 1867,+ he 
 obtained from Kopp's so-called commercial purpurin by 
 treating it with benzene and alcohol. 
 
 He states that pseudopurpurin is nearly insoluble in 
 alcohol, but very soluble in boiling benzene, from which it 
 crystallises on cooling under the form of fine needles of a 
 brick-red colour. It is converted into purpurin by the 
 
 *Jour. Chem. Soc, i860, p. 216. 
 fDeut. Chem. Ger., Ber. iii. 292. 
 % Schutzenber°:er. Traite de Matiores Colorantes. 
 
PSE UDOPURPURIN.—PURPUROXANTHIN. 37 
 
 action of heat, and the same transformation takes place 
 when it is dissolved in alcohol and heated under pressure 
 at a temperature of 400 F. 
 
 The orange substance is insoluble in boiling benzene, but 
 very soluble in hot alcohol, from which it separates in 
 orange scales. It is soluble in boiling water. When heated 
 it splits up into purpurin and water, and is therefore 
 regarded as a very stable bi-hydrate of purpurin. 
 
 The yellow colouring matter, piirpuroxanthin, is soluble 
 in alcohol and benzene, but only slightly soluble in water. 
 It may be sublimed without decomposition. The faint 
 yellow colour which it imparts to alumina mordants is 
 easily removed either by soap, or by nitro-muriate of tin. 
 
 This compound may also be obtained from purpurin, 
 pseudopurpurin, or the orange-coloured hydrate above 
 mentioned, by the action of reducing agents, such as 
 hydriodic acid, or by dissolving them in soda, adding 
 protochloride of tin until the solution acquires an orange 
 colour, and then precipitating with hydrochloric acid. 
 
 These compounds; which Schutzenberger states exist 
 naturally in madder, appear to be the products of the 
 successive oxidation, either of a colourless unknown 
 principle or of alizarin, which when liberated from its com- 
 bination with sugar, might form the various compounds 
 described. 
 
 Schutzenberger describes as follows the colours and tints 
 which each of the substances above mentioned yield to 
 mordanted cloth when dyed with proper precautions : — 
 
 Alizarin gives the usual colours which resist the action 
 of soap and nitro-muriate of tin. The reds are of a violet 
 tint, and the violets extremely pure. 
 
 Purpurin and the orange compound resist fairly the action 
 of soap and nitro-muriate of tin. The reds are very bright; 
 the violets dull and greyish. 
 
 Pseudopurpurin dyes up the mordants, but the colours so 
 
38 DYEING AND CALICO PRINTING. 
 
 produced do not resist the action either of soap or of nitro- 
 muriate of tin. The reds are clear, having a slight orange 
 hue; violets weak. 
 
 Purpuroxanthin gives colours which do not resist either 
 soap or nitro-muriate of tin. With an alumina mordant it 
 gives orange-yellow shades, and with iron pale grey. 
 
 Of the three colouring principles, isolated and described 
 by Schiitzenberger, only one, the orange compound, can be 
 considered as a true colour-giving principle; the other two, 
 pseudopurpurin and purpuroxanthin, possess no commercial 
 value, as they do not yield fast colours. 
 
 He makes the interesting remark that the fastness of the 
 colour-giving principles of madder is in inverse ratio to the 
 proportion of oxygen which they contain. 
 
 Rosenstiehl* has recently examined the colouring matters 
 existing in madder which he states to be four in number, 
 alizarin, pseudopurpurin, purpurin, and purpurin hydrate. 
 When pseudopurpurin, C 14 H 8 6 , is boiled with water, it is 
 transformed chiefly into purpurin, C 14 H 8 5 , and hydrate 
 of purpurin, but a small quantity of purpuroxanthin, 
 C 14 H 8 4 , is simultaneously produced. This reducing 
 action takes place more readily in acidulated water or in a 
 solution of alum. 
 
 M. Martin, of Avignon, states that all these compounds 
 may be easily converted into alizarin by means of reducing 
 agents in the following way : — 
 
 They are dissolved in concentrated sulphuric acid, and 
 when solution is complete zinc powder is added ; heat facili- 
 tates the action, and renders it more certain. When it is 
 finished, the mass is thrown into water, and an abundant 
 precipitate of alizarin is obtained, which it is only necessary 
 to wash to have in a state for printing. 
 
 Alizarin. — It was, as already stated, discovered in 1S2S, 
 by Robiquet and Colin. But a more convenient process for 
 
 *Compt. Rend, lxxix., 6S0. 
 
ALIZARIN. 39 
 
 obtaining it, in the anhydrous state, was devised by- 
 Schwartz, in 1856. The alcoholic extract, obtained from 
 garancin, dried and reduced to fine powder, is laid upon a 
 sheet of filtering paper, which is placed on an iron shovel, 
 so as to enable the operator to apply heat cautiously in 
 order that the paper may not be charred. The extract 
 soon melts, the paper absorbs a brown resinous matter, 
 whilst the alizarin sublimes on the surface of the mass in 
 the form of beautiful orange-coloured crystals. Pure 
 alizarin melts at 527 R, and sublimes at a. high tempera- 
 ture. It has a dyeing power ninety-five times as great as 
 that of madder. 
 
 It may be stated, as a fact very interesting, although of 
 no commercial value, that if superheated steam be passed 
 over the preparation of madder known as garancin, pure 
 alizarin is volatilised, and may be easily collected. The 
 best source of alizarin, however, is Kopp's green alizarin, 
 from which it may be extracted by hot petroleum, in the 
 manner which will be described when treating of Kopp's 
 process for extracting the colouring matters from madder. 
 
 When alizarin, obtained by Schwartz' process, is dis- 
 solved in ether, and the ether allowed to evaporate slowly, 
 it is obtained in the form of beautiful golden-coloured scales, 
 containing two equivalents of water. It exists, therefore, 
 in three forms: — 
 
 Anhydrous C 14 H 8 4 . 
 
 Bihydrate (Schwartz) C 14 H 8 4 , 2OH0. 
 
 Trihydrate (Schunck) C l4 H 8 4 , 3OH0. 
 
 Different formulae have been assigned to alizarin ; the two 
 which where formerly most generally adopted being those 
 of Schunck, C 14 H 10 O 4 , and Strecker and Wolff, Co H 12 O c ; 
 but the recent discovery of artificial alizarin, by Graebe and 
 Liebermann, and the examination of its products of trans- 
 formation have completely established the formula which 
 they proposed, viz., C u H 8 4 . 
 
40 DYEING AND CALICO PRINTING. 
 
 Cold water dissolves a mere trace of alizarin; it begins 
 to dissolve more readily at 160 F., and the solvent power 
 of the water increases as the temperature is raised, as may- 
 be seen by the following table : — 
 
 At 212° F. water dissolves "034 per cent. 
 
 3°o°F. „ -035 
 
 400 F. „ '820 „ 
 
 440°F. „ 1700 
 
 480 F. „ 3-160 „ 
 
 Schiitzenberger, in pursuing these experiments, succeeded 
 in obtaining alizarin and purpurin, in a crystalline form, 
 from an aqueous solution under very high pressure, or 
 better from a mixture of nine parts of water with one of 
 alcohol at a temperature of 480 - 5 30 F. 
 
 Alizarin is freely soluble in alcohol, ether, wood-spirit, 
 benzene, turpentine, carbon bisulphide, and glycerin. It is 
 soluble without decomposition in sulphuric acid, and is not 
 decomposed by it even at a temperature of 400 F., being 
 thrown down unchanged when the acid is diluted with a large 
 quantity of water. It is soluble in a hot solution of alum, 
 but insoluble in a cold one. 
 
 Schiitzenberger was the first chemist who succeeded in 
 reducing alizarin, which he effected by heating it to a 
 temperature of 350 F. with hydriodic acid and phosphorous 
 in sealed tubes. A more simple process is that of Bolley 
 and Rose, which consists in heating in a closed vessel a 
 solution of alizarin in potash with zinc and iron. The 
 alizarin gradually loses its purple colour, and assumes a 
 yellow tint; hydrochloric acid is then added, and the pre- 
 cipitate produced is washed with boiling water. These 
 operations must be conducted with great care, so as to pre- 
 vent the alizarin becoming reoxidised by exposure to the 
 atmosphere. The compound thus formed may be regarded 
 as a hydride of alizarin. It is decomposed by heat * 
 
 *Moniteur Scientifique, 1866, vol. viii, 9S1. 
 
NITRO-ALIZARIN. 41 
 
 If aldehyde be added to an alkajine solution of alizarin, 
 the purple liquid becomes orange on the addition of an 
 acid ; yellow flocks being precipitated. 
 
 Graebe and Liebermann, in 1868, found that when 
 alizarin is distilled with powdered zinc, it is converted into 
 anthracene, and it was this fact which lead them to employ 
 anthracene in their attempts to produce artificial alizarin. 
 
 The equation given by them for this reaction is : 
 2C U H 8 4 + OH 2 + 5Zn = Ci 4 Hio + 5Z11O. 
 
 Alizarin. Anthracene. 
 
 Berthelot found that by heating alizarin with hydriodic 
 acid in sealed tubes, hydrocarbons were formed varying 
 according to the proportions employed ; with excess of the 
 reducing agent hexane and octane are the principal 
 products. 
 
 Alizarin is easily oxidised by nitric acid, and is con- 
 verted into oxalic and phtalic acids, as shown by the 
 equation : 
 
 2C U H 3 4 + 2OH0 + 10O = 2C 2 EL0 4 + 3 C 8 H e 4 . 
 
 Alizarin. Oxalic acid. Phtalic acid. 
 
 It was the production also of this acid which led 
 Strecker and other chemists to expect that alizarin would 
 be obtained from naphthalene or some of its derivatives. 
 
 Strecker and Staedel found that by carefully acting on 
 alizarin with nitric acid a yellow crystalline compound 
 may be obtained, which is easily decomposed by water, 
 nitric oxide being liberated and a red crystalline compound 
 formed having the formula C u H 7 (N0 2 )0 5 ; as it gives 
 with alkalis and with a solution of alum the same colours 
 as purpurin, they consider it to be nitro-purpurin. 
 
 By the action of acetic anhydride on alizarin Perkin has 
 obtained a diacetyl alizarin C u H 6 4 (C 2 H 3 0) 2 crystallising 
 in yellow needles, which when treated with nitric acid yields 
 nitro-alizariii, C U H 7 (NO 2 )0 4 . The new compound crystal- 
 lises in orange-yellow needles, which dissolve in caustic 
 
42 DYEING AND CALICO PRINTING. 
 
 alkalis with a beautiful Llue colour. When nitro-alizarin is 
 acted upon by reducing agents, it is converted into amido- 
 alizarin, C 14 H 7 (NH 2 )0 4 , a substance crystallising from 
 alcohol in dark chocolate-coloured needles, with a greenish 
 metallic reflection. It may be prepared by boiling the 
 alkaline solution of nitro-alizarin with granulated zinc until 
 the blue colour has disappeared, and then neutralising with 
 an acid. Its solutions are of a crimson colour. 
 
 Nitro-alizarin produces, with alumina mordants, an 
 orange-red colour, similar to aurin, and with iron mordants 
 a reddish purple, whilst amido-alizarin gives a purple with 
 alumina mordants, and a bluish violet colour with iron. 
 They both dye unmordanted silk, nitro-alizarin a clear 
 golden colour, and amido-alizarin a purple-red. 
 
 Alizarin combines with alkalis to form salts, which are 
 slightly soluble in alcohol but insoluble in ether. The 
 alizarate of soda crystallises easily from alcohol; the solu- 
 tion of this salt has a beautiful purple colour. 
 
 Alizarin forms insoluble compounds with the alkaline 
 earths and metallic oxides, giving salts or lakes of a variety 
 of colours, those of the alkaline earths being violet, those 
 of alumina red or pink, and those with the persalts of iron 
 purple or black. Alumina has such an affinity for alizarin 
 that it entirely removes it from its solutions. 
 
 Schutzenberger states that if an ammoniacal solution of 
 alizarin is kept for some weeks at the ordinary temperature, 
 or is heated to 21 2° F. in a closed vessel, a chemical 
 change ensues, with formation of a compound which when 
 dry is an amorphous black mass. This he considers to be 
 an amide of alizarin or alizaramide, and assigns to it the 
 improbable formula C H 12 O G NH 3 . If dissolved in hot 
 alcohol it separates on cooling as a crystalline powder. 
 It communicates to ether and water a beautiful violet-red 
 hue. It yields colours to mordanted fabrics, but they are 
 not so bright as those of madder. 
 
ALIZARINAMIDE. 43 
 
 Liebermann and Troschke,* have recently examined this 
 reaction, and find that when a solution of pure alizarin in 
 aqueous ammonia is heated to about 350 F., alizarinamide, 
 C U H 9 N03 or C 14 H 7 (NH 2 )0 3 , is produced. When pure it 
 crystallises from alcohol in beautiful brown irridescent 
 needles, which dissolve in alkalis with a purple-blue colour. 
 Its alcoholic solution is brownish yellow. Alizarin is regen- 
 erated when it is heated with strong hydrochloric acid to 
 480. If, however, a large quantity of precipitated alizarin 
 be heated as above with strong ammonia, crystals separate 
 out on cooling, which, after being digested with dilute 
 hydrochloric acid, have the composition of alizarinimide, 
 C^H 7 NO or C U H 6 (NH)O 2 . It closely resembles alizarin- 
 amide in appearance, but is scarcely soluble in ammonia 
 or in cold alkaline solutions. 
 
 By heating a mixture of sodium alizarate with ethyl 
 iodide in sealed tubes, at 250 F., Schiitzenberger obtained 
 an ethyl derivative of alizarin, which appears to have the 
 formula C u H (C 2 H 5 ) 2 O 4 . It is of a pale yellow colour, 
 and is insoluble in water but soluble in alcohol. 
 
 He also obtained a benzoic derivative by heating a mix- 
 ture of benzoyl chloride and alizarin to 375 ° F. In this 
 reaction hydrochloric acid and a yellow compound are 
 produced. The latter is insoluble in water but soluble 
 in alcohol, from which it is deposited in a crystalline 
 state. It is decomposed by a boiling solution of alkali 
 into benzoate and alizarate of the alkali. Its formula is 
 C u H 6 (C 7 H 5 0) 2 4 . In 1864, Stenhouse prepared a brom- 
 alizarin by pouring an alcoholic solution of alizarin into 
 water, adding a slight excess of bromine water, filtering 
 and gently heating. As the alcohol evaporated the new 
 compound crystallised out in dark-brown needles. 
 
 As already stated, Graebe and Liebermann by heating 
 alizarin with zinc dust obtained the hydrocarbon anthra- 
 
 * Deut. Chem. Ger. Bes. viii., 379. 
 
44 DYEIXG AND CALICO PRINTING. 
 
 cene, which had been discovered in 1832 by Dumas and 
 Laurent, amongst the products formed in the destructive dis- 
 tillation of coal. They next attempted to reverse the process, 
 and after considerable labour, succeeded in obtaining a pro- 
 duct which yields all the brilliant colours for so long a time 
 obtained only from the rubia root. This discovery of 
 Graebe and Liebermann is one of the most interesting and 
 important applications of chemistry to the arts that has 
 been made of late years. Although the alizarin obtained 
 from the madder root and that prepared artificially from 
 anthracene give the same absorption bands in the spectrum, 
 and when applied to mordanted fabrics produce exactly the 
 same colours bearing the soap trial equally well, yet for 
 some time it remained a matter of doubt as to whether 
 the two were absolutely identical, as there were certain 
 slight differences which were not explained until it was 
 found that the artificial product was not pure alizarin but 
 contained other substances. The most important of these 
 are anthraflavic acid and anthrapurpurin. Anthrajiavic 
 acid, which was first noticed by Schunck, and has since 
 been carefully examined by Perkin and by Auerbach, is 
 isomeric with alizarin, having the composition represented 
 by the formula C u H 8 4 . To separate it, crude artificial 
 alizarin is dissolved in boiling dilute caustic soda, and milk 
 of lime is added until the solution becomes yellow or 
 orange. It is then filtered from the purple alizarin lake 
 and precipitated with hydrochloric acid. The precipitate 
 after being washed by boiling it with alcohol is dissolved 
 in caustic soda, and filtered from the insoluble impurities. 
 On adding excess of barium chloride to the boiling solution 
 and allowing it to cool, barium anthrafiavate crystallises 
 out in reddish-brown needles. The acid is readily ob- 
 tained from this by decomposing it with an acid. Anthra- 
 flavic acid crystallises from alcohol in yellow silky needles, 
 which yield a nitro compound with fuming nitric acid. 
 
ANTHRAPURPURIN. 45 
 
 When fused with potash, anthraflavic acid yields a red 
 substance, which dyes alumina mordants an orange-red 
 colour. 
 
 The most convenient method of obtaining Perkin's anthra- 
 purpurin* from crude artificial alizarin is to dissolve it in 
 dilute carbonate of soda, and agitate the solution with 
 freshly precipitated alumina, which combines with the 
 alizarin to form a lake, whilst the anthrapurpurin remains 
 dissolved. On filtering and adding hydrochloric acid to 
 the clear liquid, previously heated to boiling, the anthra- 
 purpurin is precipitated in an impure state, being associated 
 with a substance which gives an orange colour with alumina 
 mordants, anthraflavic acid, &c. The impure product is 
 washed repeatedly with boiling alcohol, then digested with 
 boiling alcoholic soda, and the difficultly soluble sodium 
 compound washed several times with dilute alcoholic soda, 
 after which it is dissolved in boiling water and precipitated 
 by barium chloride. The purple precipitate is washed with 
 hot water, boiled with carbonate of soda, and the clear 
 purple solution, after being separated from the carbonate of 
 barium by filtration, is precipitated with hydrochloric acid. 
 Anthrapurpurin, C U H 8 5 , crystallises from glacial acetic 
 acid in minute orange-coloured needles. It is soluble with 
 difficulty in alcohol and ether, and only very slightly soluble 
 in water. It dyes cloth, mordanted with alumina, red, and 
 gives purple and black shades with iron mordants, but the 
 reds are much purer and less blue than those of alizarin, 
 whilst the purples have a bluer shade and the blacks are 
 more intense. The fastness of the colours against soap 
 and light are quite equal to those produced with alizarin. 
 With Turkey red mordant it produces a brilliant scarlet, 
 which is remarkable for its permanence. 
 
 Liebermann has succeeded in isolating from the crude 
 alizarin a compound having the formula C u H 8 3 , which 
 *Jour. Chem. Soc, xxvi., 425. 
 
46 DYEING AND CALICO PRINTING. 
 
 he considers to be monoxyanihraquinone. It closely re- 
 sembles anthraflavic acid in most of its properties, but is 
 easily soluble in cold baryta water, whilst anthraflavic acid 
 is nearly insoluble. 
 
 Anthracene is one of the last products passing over in 
 the dry distillation of coal-tar, and is found most abundantly 
 in the 10 or 15 per cent, which comes over between the 
 temperature at which soft pitch is produced, and that at 
 which hard pitch is formed. The quantity of anthracene 
 in coal-tar varies greatly, but is most abundant in the tars 
 obtained from those coals which yield most naphtha. The 
 South Staffordshire coals give the largest quantity, whilst 
 the Newcastle coals give very little. Its extraction can 
 only be carried on with advantage in cold weather, as on a 
 slight rise of temperature it becomes very soluble in the 
 oily hydrocarbons which accompany it. The distillate 
 above described, which at a temperature of about 40 F. is 
 semi-fluid, is placed in a hydro-extractor, and the oily fluid 
 separated from the solid matter. In this state it contains 
 from 30 to 45 per cent, of anthracene. 
 
 The pasty mass is now very carefully submitted first to 
 cold pressure, and afterwards whilst warm. It is then 
 powdered and passed through a sieve, after which it is 
 washed methodically with petroleum spirit, having a boiling 
 point varying from 160 to 195 ° F., when it is again sub- 
 mitted to hydraulic pressure. After being resublimed it is 
 in a fit state for the manufacture of alizarin. 
 
 Pure anthracene presents itself under the form of flu- 
 orescent transparent crystals, consisting of four or six- 
 sided plates, which have a peculiar very pale blue hue 
 when seen by transmitted light, changing to pale violet 
 by reflected light. Its preparation is a very tedious pro- 
 cess, for which as well as for its tests (differing only in 
 degree from those for the commercial article), we must 
 refer the reader to the beautiful resume, on anthracene 
 
ANTHRACENE. 47 
 
 and its derivatives, by M. Emile Kopp, in the Moniteur 
 Scientifique.* 
 
 When allowed to crystallise slowly from alcohol it 
 forms oblique prisms with regular bases belonging to 
 the monoclinic system ; it begins to volatilise at a 
 temperature of 21 2° F., giving off vapours which have a 
 peculiarly disagreeable odour, and are very irritating to the 
 throat and eyes. It melts at 410 F. and boils at a tempera- 
 ture between 6io° and 630 F., when it sublimes in crystals, 
 very similar to those described above, the vapours of which 
 are so dense that the crystals condense on the top and in 
 the neck of the retort. This latter fact suggested to the 
 author that a much larger yield of anthracene might be 
 obtained if during the distillation steam superheated to a 
 temperature of between 6oo° and 700 F. were blown 
 through the oily mass. The results obtained were very 
 satisfactory. 
 
 Anthracene is only slightly soluble in alcohol, but 
 rather more so in ether and bisulphide of carbon. It is 
 more soluble in hot benzene, but less in cold. Petroleum 
 boiling between 160 and 195 F, dissolves less than 
 benzene. 
 
 In the cold, alcohol dissolves '6 per cent, benzene '9, and 
 bisulphide of carbon 1 7 of anthracene. Alkalis even when 
 boiling have no action upon it. Anthracene dissolves in 
 concentrated sulphuric acid with a green colour, and forms 
 conjugated monosulpho or bisulpho-anthracenic acid,accord- 
 ing to the temperature employed. Chlorine and bromine 
 give rise to substitution products. Nitric acid acts on it with 
 great violence, with formation of anthraquinone, dinitro- 
 anthraquinone, and other compounds, according to the 
 temperature and proportion of the substances taken. With 
 picric acid anthracene forms a compound, crystallising in 
 very bright ruby-red needles, which, by the aid of the 
 
 *Vol. xiii., p. 531. 
 
4 8 DYEING AND CALICO PRINTING. 
 
 microscope are seen to be prisms. To prepare it, a saturated 
 solution of picric acid in water at 8o° F. is mixed with a 
 saturated solution of anthracene in boiling alcohol ; on cool- 
 ing, the compound is deposited in the crystalline state. It is 
 rapidly decomposed by an excess of alcohol into picric acid 
 and anthracene, the solution assuming a yellow tint. This 
 reaction can be employed to distinguish anthracene from 
 naphthalene and other hydrocarbons, naphthalene under 
 similar circumstances forming a compound which crystal- 
 lises in fine golden-yellow needles, whilst chrysene gives 
 rise to clusters of very small yellow needles. 
 
 Another characteristic of anthracene observed by Fritzsche 
 is its behaviour under the microscope with a solution of 
 binitro-anthraquinone in benzene. In this reaction fine 
 rhomboidal scales having a beautiful pink colour are formed, 
 the purity and brilliancy of the colour of course depending 
 on the purity of the anthracene. 
 
 Before leaving this subject, it may be stated that Ber- 
 thelot* has described several reactions in which anthracene 
 is formed ; as by the action of heat on other hydrocarbons, 
 or by passing the vapours of ethylene, styrolene, and ben- 
 zene through a porcelain tube heated to a bright red heat. 
 
 The method by which Messrs. Graebe and Liebermann 
 first succeeded in obtaining artificial alizarin consisted in 
 transforming anthracene C U H 10 into anthraquinone C u H 8 2 
 by the action of nitric acid, which removes two equivalents 
 of hydrogen from the hydrocarbon and adds two of oxygen. 
 The anthraquinone thus obtained is acted on by bromine 
 which replaces two equivalents of hydrogen and gives rise 
 to bibromanthraquinone C u H Br 2 O 2 . This compound 
 when fused with hydrate of potash yields bromide of potas- 
 sium and alizarin according to the following equation : 
 
 C u H 6 Br 2 2 +2KHO = C 14 H 8 4 + 2KEr. 
 This process, although important from a scientific point of 
 
 * Bui. Soc. Chim., vii., 274. 
 
ANTHRAQUINONE. 49 
 
 view, could not be carried out on a practical scale, being 
 much too costly; a cheaper method was therefore looked 
 for. 
 
 The best laboratory process for the production of anthra- 
 quinone consists in making separate solutions of anthracene 
 and chromic acid in glacial acetic acid, and gradually adding 
 the chromic acid solution to the anthracene until the liquid, 
 which is at first bright green, assumes a slightly yellow 
 tinge, showing that there is chromic acid in excess. On the 
 liquid being allowed to cool needles of anthraquinone 
 crystallise out, the amount of which may be increased by 
 adding water to the solution. The crude substance is col- 
 lected on a filter, washed, dried, and sublimed, when it 
 yields yellow crystals of pure anthraquinone, the formula of 
 which is, as stated above, C u H s 2 . 
 
 It is more economical to substitute sulphuric acid for 
 acetic acid, and bichromate of potash or peroxide of man- 
 ganese for the chromic acid, which is the method adopted 
 in the patented process. 
 
 The crystalline form which anthraquinone assumes de- 
 pends on the exact method and temperature employed in 
 its sublimation. It is insoluble, or only very slightly solu- 
 ble, in alcohol, ether, and benzene. It melts at 520 F., 
 and distils at a higher temperature without decomposition. 
 Its power of resisting the action of chemical reagents is 
 very characteristic. 
 
 If anthraquinone be heated with hydrate of potash in a 
 silver crucible to a temperature of 480 F. the mass becomes 
 blue, as if alizarin were produced, but on the addition of 
 water it loses its colour and the anthraquinone reappears 
 in the form of colourless flocks. Wartha* finds that 
 when caustic potash is added to an alcoholic solution of 
 anthraquinone the colourless solution quickly assumes a 
 yellowish tinge, and if the application of heat be continued 
 
 Ann. Chem. Pharm. clxi., 305. 
 
50 DYEING AND CALICO PRINTING. 
 
 until the whole of the alcohol is given off and the mass 
 fuses, it becomes first greenish and then takes the peculiar 
 voilet-purple tint characteristic of the presence of alizarate 
 of potash ; in fact from this mass he succeeded in obtaining 
 alizarin in small quantity. He observed that the addition 
 of chloride of tin greatly facilitates the transformation, and 
 that if the anthraquinone be mixed with twice its weight of 
 cthylate of sodium (a product obtained by the action of 
 sodium on anhydrous alcohol) the same effect is produced. 
 These observations of Wartha are interesting as they show 
 that alizarin can be produced directly from anthraquinone 
 without previously converting it into bisulpho-anthra- 
 quinonic acid. 
 
 Anthraquinone may be boiled with sulphuric acid of 
 specific gravity 1*4, without alteration. With a mix- 
 ture of concentrated nitric and sulphuric acids it is con- 
 verted into binitro-anthraquinone C u H 6 (X0 2 ). 2 . Anthra- 
 quinone dissolves in cold concentrated sulphuric acid, and if 
 the mixture be strongly heated for some time bisulpho- 
 anthraquinonic acid C U H S 2 2S0 3 is formed. When this 
 bisulpho-anthraquinonic acid is heated at 360 F. with an 
 excess of potassium hydrate, it gives rise to sulphite and 
 alizarate of potash, as shown in the following equation : — 
 
 C 14 H S 2 2S0 3 +6KHO = C u H G K. 2 4 + 2 K a SO s -4OH. 
 
 There have been several patents taken out for the manu- 
 facture of artificial alizarin. The specification of Messrs. 
 Caro, Graebe, and Liebermann, here given, was the first 
 which was taken out in England, and enters more fully 
 into detail than any of the others. The provisional specifi- 
 cation was dated June 25 th, 1869. 
 
 "Our invention is carried into effect by means of either 
 "of the two processes, which we will proceed to describe. 
 
 "In the one process we proceed as follows: — We take 
 "about one part by weight of anthraquinone and about 
 "three parts by weight of sulphuric acid of about the 
 
ARTIFICIAL ALIZARIN. 
 
 51 
 
 "specific gravity of 1-848, and introduce the same into a 
 "retort, which may be made of glass, or of porcelain, or of 
 "other material not easily acted upon by sulphuric acid, 
 "and the contents are then to be heated up to about two 
 "hundred and sixty degrees centigrade, and the tempera- 
 ture is maintained until the mixture is found no longer to 
 "contain any appreciable quantity of unaltered anthra- 
 "quinone. The completion of this desired operation may 
 "be ascertained or tested by withdrawing a small portion 
 "of the product from time to time and continuing the 
 "operation at the high temperature until such product 
 "upon being diluted with water is found to form a sub- 
 stantially perfect solution, thereby indicating that the 
 "anthraquinone has become either entirely or in greater 
 "part converted into the desired product. • The results of 
 "this operation are then allowed to cool and are diluted 
 "with water: we then add carbonate of lime in order to 
 "neutralize and remove the excess of sulphuric acid con- 
 "tained in the solution; the mixture is then filtered, and to 
 "the filtrate carbonate of potash or carbonate of soda, by 
 "preference in solution, is to be added until carbonate of 
 "lime is no longer precipitated; the mixture is then filtered 
 "and the clear solution is evaporated to dryness, by which 
 "means the potash or soda salts of what we call thesulpho- 
 " acids of anthraquinone are obtained and which are to be 
 "treated in the following manner: — We take about one 
 "part by weight of this product and from two to three 
 "parts by weight of solid caustic soda or potash; water 
 "may be added or not, but by preference we add as much 
 "water as is necessary to dissolve the alkali after admix- 
 ture; we heat the whole in a suitable vessel, and the 
 "heating operation is continued at a temperature of from 
 "about one hundred and eighty degrees to about two 
 "hundred and sixty degrees centigrade for about one hour 
 "or until a portion of the mixture is found upon with- 
 
52 DYEIXG AND CALICO PRINTING. 
 
 "drawing and testing it to give a solution in water, which 
 "being acidulated with an acid, for example sulphuric acid, 
 "will give a copious precipitate of the colouring matters. 
 "The heating operation having been found to have been 
 "continued for a sufficient time the resulting products are 
 "then dissolved in water, and we either filter or decant the 
 "solution of the same, from which we precipitate the 
 "colouring matters or artificial alizarin by means of a 
 "mineral or organic acid, such, for example, as sulphuric 
 "or acetic acid. The precipitated colouring matters thus 
 "obtained are collected in a filter or otherwise, and after 
 "having been washed may be employed for the purposes of 
 "dyeing and printing either in the same way as prepara- 
 tions of madder are now used, or otherwise. 
 
 "In carrying out our other process we proceed as follows : 
 ''We take about one part by weight of anthracene and 
 "about four parts by weight of sulphuric acid of specific 
 "gravity of about I'S^S, and the mixture being contained 
 "in a suitable vessel is heated to a temperature of about 
 "one hundred degrees centigrade, at which temperature it 
 "is to be maintained for the space of about three hours ; 
 "the temperature is then to be raised to about one hundred 
 "and fifty degrees centigrade, which temperature is to be 
 "maintained for about one hour or until a small portion of 
 "the product when submitted to the subsequent processes 
 "herein-after described is found to produce the desired 
 "colouring matters; we then allow the result obtained by 
 "this operation to cool, and dilute it with water, by prefer- 
 ence in the proportion of about three times its weight. 
 "To the solution thus obtained we add for ever)- part of 
 "anthracene by weight which had been employed in the 
 "previous operation about from two to three parts by 
 "weight of peroxide of manganese, preferring to employ an 
 "excess, and we boil the whole strongly for some time, and 
 "in order fully to ensure the desired degree of oxidation 
 
GRAEBE 'S PA TENT. 5 3 
 
 "the mixture may be subsequently concentrated and by 
 "preference be evaporated to dryness and the heat be con- 
 "tinued until a small portion of the oxidised product when 
 "submitted to the subsequent processes herein-after de- 
 scribed will produce the desired colouring matters. We 
 "then neutralise and remove the sulphuric acid contained 
 "in this mixture, and at the same time precipitate any 
 "oxides of manganese which may be held in solution by 
 "adding an excess of caustic lime which we use by prefer- 
 ence in the form of milk of lime, and we add the same 
 "until the mixture has an alkaline reaction. We then filter 
 "and add to the filtrate carbonate of potash or soda until 
 "there is no further precipitation of carbonate of lime. 
 "The solution is then filtered and evaporated to dryness, 
 "and we thus obtain the potash or soda salts of what 
 "we call the sulpho-acids of anthraquinone. 
 
 "In effecting the conversion of the oxidised products 
 "thus obtained into colouring matters, or into what we call 
 "artificial alizarin, we proceed as follows : — We take one 
 "part by weight of this product and from two to three 
 "parts by weight of solid caustic soda or potash, and water 
 "may be added or not, but by preference we add as much 
 "water as is necessary to dissolve the alkali. After admix- 
 "ture we heat the whole in a suitable vessel and continue the 
 "heating operation at a temperature from about one hun- 
 "dred and eighty degrees to about two hundred and sixty 
 "degrees centigrade for about one hour, or until a portion of 
 "the mixture is found to give a solution in water which upon 
 "acidulation with an acid, for example sulphuric acid, is 
 "found to give a copious precipitate of the colouring 
 "matters. The heating operation having been found to 
 "have been continued for a sufficient time we then dissolve 
 "the product in water, and either filter or decant the solution 
 "of the same, from which we precipitate the colouring 
 "matters or artificial alizarin by means of a mineral or 
 
54 DYEING AND CALICO PRINTING. 
 
 "organic acid, such, for example, as sulphuric or acetic 
 "acid. The precipitated colouring matters thus obtained 
 "are collected on a filter or otherwise, and after having 
 "been washed may be employed for the purposes of dyeing 
 "and printing either in the same way as preparations of 
 "madder arc now used or otherwise. Instead of acting 
 "upon anthracene by means of sulphuric acid of the density 
 "before mentioned, fuming sulphuric acid may be employed, 
 "but we prefer to use the ordinary acid, as before described. 
 
 "In order to effect the process of oxidation before re- 
 ferred to, other oxidising agents may be used in place of 
 "the peroxide of manganese before mentioned, such, for 
 "example, as peroxide of lead, or chromic, nitric, or other 
 "acids capable of effecting the desired oxidation may be 
 "employed." 
 
 Mr. W. H. Perkin also took out a patent only one day 
 later, his process being exactly the same in principle. 
 
 MM. Brcenner and Gutzkon patented in France, in May, 
 1869, a process differing from the two already mentioned, of 
 which the following is an outline : — One part of anthracene 
 is heated with two parts of nitric acid of specific gravity 
 1 '3 to 1*5. The anthraquinone thus produced is washed 
 and dissolved at a moderate heat in sulphuric acid. Mer- 
 curic nitrate is now added, which converts the anthra- 
 quinone into alizarin. The mass thus formed is dissolved 
 in an excess of alkali, which precipitates the oxide of 
 mercury and retains the colouring matters in solution. 
 The alkaline liquor is decanted and neutralised with 
 sulphuric acid, and the precipitate thus formed is washed 
 and collected. If not quite pure the treatment with alkali 
 must be repeated.* 
 
 A large quantity of artificial alizarin is now manufactured 
 in England by Perkin's process, and it is used as a substi- 
 
 *For complete specification see Moniteur Scientifique, vol. xi., p. 865. 
 
ANTHRACENE ORANGE. 55 
 
 tute for madder and extract of madder in Turkey red dye- 
 ing and topical styles. 
 
 On the continent the largest manufacturers are Messrs. 
 Gessert Freres, of Ebelfert; Messrs. Meister, Lucius, and Co., 
 of Hcechst, near Frankfort ; and the Badische Anilin und 
 Soda Fabrik, Mannheim. 
 
 According to Bcettger, a fine orange colour can be obtained 
 from anthracene by heating slowly to about 70° F., one part 
 of anthraquinone with sixteen times its weight of a mixture 
 of sulphuric acid of specific gravity r84, and nitric acid of 
 specific gravity 1*50. When the anthraquinone is dissolved, 
 the mixture is immediately poured into a large quantity of 
 water, and a nitrogenised compound separates in voluminous 
 yellowish-white flakes. These are collected and acted on by 
 a solution of protoxide of tin in alkali, which dissolves the 
 flakes, assuming at the same time a magnificent emerald 
 green tint. On boiling this solution the anthracene orange 
 is precipitated as a beautiful cinnabar red powder, having 
 the formula C 14 H 6 No 6 . When heated to a temperature 
 of 500 F. it sublimes in fine red needles, which have a 
 green iridescence. Its best solvents are chloroform, ether, 
 alcohol, and wood spirit. 
 
 Colours somewhat similar to alizarin have been prepared 
 from naphthalene, but they will not stand a soaping process. 
 The first of these was obtained by Roussin in 1861, who 
 gave it the name of naphthazarin. Its formula is C 10 H 4 O 4 . 
 For some little time after its discovery it was believed to 
 be alizarin; in fact, Dumas, then president of the academy 
 of sciences, introduced it to that assembly as alizarin. It is 
 prepared by the following simple process. 
 
 Five hundred grammes of concentrated sulphuric acid are 
 mixed with one hundred of dinitronaphthalene in a large por- 
 celain capsule and gradually heated to 350 F. The source 
 of heat is then removed and one hundred grammes of crys- 
 tallised protochloride of tin or granulated zinc is gradually 
 
56 DYEING AND CALICO PRINTING. 
 
 added in very small quantities at a time. If too much of 
 the reducing agent be added at one time, the temperature 
 rises rapidly and the operation is spoiled. For if the heat 
 reaches 400° F. the colour is destroyed, whilst at 480 F. 
 the whole mass becomes carbonised. The product result- 
 ing from this reaction is allowed to cool. Hot water is then 
 added, the mixture boiled, and rapidly filtered. A beauti- 
 ful purple-red liquor is obtained, from which, on cooling, the 
 naphthazarin separates in the form of small flakes or 
 crystals. One hundred parts of binitronaphthalene yield 
 only five parts of naphthazarin. 
 
 This colouring matter dissolves in alkalis, but its solu- 
 tion is more violet than that of purpurin, and not so blue 
 as that of alizarin. On fabrics with alumina mordants it 
 gives a red, more or less purple, and with iron mordants a 
 greenish-grey. 
 
 A second product called oxynaphthalic acid, having the 
 formula C 10 H G O 3 , was prepared by Martius and Griess in 
 1866. Many eminent chemists thought at that time that 
 alizarin was oxynaphthalic acid, and were occupied in 
 attempting to prepare this compound. When it was ob- 
 tained, however, it was found to differ considerably from 
 alizarin. 
 
 The process followed by Martius and Griess has since 
 been considerably improved by Graebe and Ludwig. Their 
 method is as follows : 
 
 One part of dinitronaphthol, two parts of granulated tin, 
 and seven and a half parts of concentrated hydrochloric acid 
 arc heated in a large capsule until a violet colour is pro- 
 duced. As soon as this appears the source of heat is 
 removed, that generated by the chemical action being suffi- 
 cient to complete the transformation. Water is then added, 
 and plates of zinc are placed in the solution, whereby the 
 tin is thrown down and replaced by the zinc, which dis- 
 solves. The precipitated metal is removed by filtration, and 
 
OX YNAPHTHALIC A C/D. 5 7 
 
 perchloride of iron is added to the nitrate as long as any 
 precipitate is produced. This is collected on a filter and 
 washed with cold water. After being dissolved in boilingr 
 water and allowed to cool, prisms or rhomboidal tables 
 separate which are red by transmitted light and green by 
 reflected light. The two following equations show the re- 
 actions : 
 
 C 10 H 6 (NO 2 ) 2 O + 6Sn + 14HCI = C 10 H c (NH 2 ) 2 O. 2HCI. 
 . Dinitronaphthol. Tin. Hydrochloric Diamidonaphthol hydro- 
 
 acid, chloride. 
 
 + 6SnCl 2 +40H 2 . 
 Stannous Water, 
 chloride. 
 
 C 10 H 10 N 2 O. 2 HCl + Fe 2 Cl fi =C 10 H 8 N 2 O. HC1. 
 
 Hydrochloride of di- Hydrochloride of di- 
 
 amidonaphthol. imidonaphthol. 
 
 + 2FeCl 2 + 3 HCl. 
 
 To complete the transformation, the crystals of hydro- 
 chloride of diimidonaphthol are boiled for an hour with a 
 quantity of sulphuric acid of such strength that its boiling 
 point is 250 F. The following reaction ensues : 
 
 C 10 H 8 N 2 O. HC1 + H 2 S0 4 + zOH 2 = C 10 H G O 3 + (NH 4 ) 2 S0 4 
 
 Hydrochloride of Sulphuric acid. Oxynaphthalic Sulphate of 
 diimidonaphthol. acid. ammonia. 
 
 + HC1. 
 
 Hydrochloric acid. 
 
 The solution thus obtained is boiled with carbonate of 
 baryta, which precipitates the sulphuric acid, leaving the 
 oxynaphthalic acid in solution combined with baryta. On 
 the addition of hydrochloric acid to this solution the oxy- 
 naphthalic acid is precipitated in the form of small needles, 
 which are only slightly soluble in water even when boiling, 
 and which can be sublimed in slender needles very similar 
 to those of sublimed alizarin. 
 
58 DYEING AND CALICO PRINTING. 
 
 This acid differs from alizarin in yielding, with ammonia, 
 a yellowish- red colour instead of a bluish-violet; moreover, 
 it combines with ammonia to form a well-defined salt. 
 The precipitate which it gives with the various metallic salts 
 are quite different from those obtained with alizarin. It 
 imparts a yellow colour to silk and wool, but does not yield 
 any colour to alumina mordants. 
 
 Purpurin. — Like alizarin, this substance forms crystal- 
 line compounds with the alkalis, that of soda crystallising 
 in well-defined elongated prisms. With salts of alumina 
 it gives a red-lake free from all blue tint, and with persalts 
 of iron purples and blacks. It forms an amido com- 
 pound similar to that obtained from alizarin. This was 
 discovered by Stenhouse in 1864, who found that a solu- 
 tion of purpurin in ammonia when allowed to stand for 
 several weeks loses its power of dyeing mordanted cloth. 
 On neutralising the solution, a dark-red crystalline precipi- 
 tate is produced, which is soluble in a large quantity of 
 boiling water, and separates again on cooling in long crim- 
 son needles, which have a deep green iridescence by 
 reflected light. They are soluble in alcohol. Its formula 
 appears to be C u H 9 N0 4 or C u H 7 (NH 2 )0 4 . Schiitzen- 
 berger has also prepared purpurinamide by heating purpurin 
 with ammonia in sealed tubes to the temperature of boiling 
 water. 
 
 Purpurinamide, as shown by Stenhouse, dissolves freely 
 in nitric acid of specific gravity 1*5 at a temperature of 
 212 F., and yields on cooling magnificent scarlet crystals, 
 which somewhat resemble chromate of silver in appearance, 
 but have a brighter colour. They are insoluble in water, 
 ether, and bisulphide of carbon, but are slightly soluble in 
 alcohol. 
 
 No crystalline compounds have as yet been obtained by 
 the action of bromine on purpurin. 
 
 When investigating the hydride of alizarin, Bolley 
 
HYDRIDE OF PUR PUR IN. 59 
 
 observed that purpurin underwent a similar change to 
 the alizarin, the red alkaline solution of purpurin 
 passing into orange, and finally to a brownish-yellow, 
 when treated with reducing agents. In operating with 
 equal care, as in the case of alizarin, to prevent the ab- 
 sorption of oxygen from the atmosphere, he obtained a 
 floculent precipitate which is easily sublimed in long golden- 
 yellow needles. There appears to be no difference in com- 
 position between the body before and after sublimation. 
 The formula assigned to it by Bolley is C 20 H 16 O 5 (?), who con- 
 siders purpurin to be C 20 H 12 O 7 (?). The hydride dissolves 
 readily in alcohol or ether, but is less soluble in water or 
 benzene. These solutions keep very well when exposed to 
 the atmosphere, but its alkaline solution gradually absorbs 
 oxygen and acquires a red colour. It is also soluble in a 
 solution of alum. Bolley also states that if purpurin is 
 heated in sealed tubes to a temperature of 400 F. it forms 
 a carbonaceous mass from which water extracts alizarin. 
 This conversion can also be effected by heating the pur- 
 purin with water in sealed tubes to the same temperature. 
 Under the influence of the high temperature the purpurin 
 loses oxygen and is converted into alizarin. Rosenstiehl,* 
 on the contrary, finds that picre purpurin yields no alizarin 
 under these circumstances, and attributes the supposed 
 transformation observed by Bolley to the use of impure 
 purpurin. 
 
 Professor Stokes, of Cambridge, has devised a most ele- 
 gant method of discovering and distinguishing mere traces 
 of these colouring principles. The following is a clear 
 and concise description of his useful and practical process, 
 which is inserted as an appendix to Schunck's paper on 
 madder in the Journal of the Chemical Society: — f 
 
 *Compt. Rend., lxxix., 680. 
 + Vol. xii., p. 219. 
 
60 DYEING AND CALICO PRINTING. 
 
 The optical characters of purpurin are distinctive in the 
 very highest degree; those of alizarin are also very dis- 
 tinctive. The characters here referred to consist in the 
 mode of absorption of light by certain solutions of the 
 bodies, and occasionally in the powerful iridescence of a 
 solution. They are specially valuable because they are 
 independent of more than a moderate degree of purity of 
 the specimens, and require no apparatus beyond a test-tube, 
 a slit, and a small prism, an instrument which ought to be 
 in the hands of every chemist. 
 
 Alkaline solution of purpurin. — If purpurin be dissolved 
 in a solution of carbonate of potash or soda (it is easily 
 decomposed by caustic alkalis), the solution obtained 
 absorbs with great energy the green part of the spectrum. 
 In this and similar cases it is necessary to take care 
 either to use a sufficiently small quantity of the substance 
 or else to dilute sufficiently the solution, or view it through 
 a sufficiently small thickness ; otherwise a broad region of 
 the spectrum is absorbed, and the peculiar characters of the 
 substance depending on its mode of absorbing light are 
 not perceived. If the solution be contained in a wedge- 
 shaped vessel, the effect of different thicknesses is seen at 
 a glance ; but a test-tube will answer perfectly well, if two 
 or three different degrees of dilution be tried in succession. 
 When the light transmitted through an alkaline solution of 
 purpurin of suitable strength, after being limited by a slit, 
 is viewed through a prism, two remarkable dark bands of 
 absorption are seen about the green part of the spectrum, 
 comprising between them a band of green light, which, 
 though much weakened in comparison with the same part 
 of the unabsorbed spectrum, is bright compared with the 
 two dark bands, which latter in a sufficiently strong solution 
 appear perfectly black. The places of the dark bands, 
 estimated with reference to the principal fixed lines of 
 the spectrum, are given in the figure. 
 
SPECTRUM OF PURPURIN. 
 
 6l 
 
 B C 
 
 E b 
 
 
 
 Villi 
 
 
 
 
 II 
 
 
 • 1 
 
 111 
 
 f 
 
 
 
 
 III !| 1: ' M 
 
 
 
 ';-!:!' •i'>k;y.\'h 
 
 jll 
 
 III 
 
 II 
 
 ll 
 
 
 Fig. I. — Solution of pur- 
 purin in carbonate of soda or 
 potash, or in alum-liquor. 
 
 Fig 2. — Solution of pur- 
 purin in bisulphide of carbon. 
 
 Fig. 3. — Solution of pur- 
 purin in ether. 
 
 Fig. 4. — Alkaline solution 
 of alizarin. 
 
 Solution in a solution of alum. — This solution has the 
 same peculiar mode of absorption, and will serve equally 
 well for it. But it has the further property of being emi- 
 nently iridescent, which the alkaline solution is not at all. 
 The iridescent light is yellow, but ordinarily appears 
 orange from being seen through the fluid. The difference 
 between the alkaline and alum liquor solutions as to iri- 
 descence does not depend on the acid reaction of the latter, 
 but on the alumina. A solution, exhibiting to perfection the 
 peculiar properties of the alum liquor, may be obtained by 
 adding to a solution of purpurin in carbonate of soda a 
 solution of alum to which enough tartaric acid has been 
 added to prevent precipitation when carbonate of soda is 
 added, which must be done previous to mixing, and in this 
 case the solution is obtained at once and in the cold. This 
 forms a very striking reaction in a dark room, according to 
 the method described in the Philosophical Transactions for 
 1853, p. 385, with the combination solution of nitrate of 
 copper and a red (Cu 2 0) glass. Some other colourless 
 oxides, besides alumina, develope in this manner iridescence 
 although in a less degree. 
 
 Solution in bisulphide of carbon. — This solution gives 
 the highly characteristic spectrum exhibiting four bands of 
 absorption, of which the first is narrower than the others, 
 and the fourth is not at all conspicuous, hardly standing 
 out from the general absorption which takes place in that 
 
62 DYEIXG AXD CALICO PRINTIXG. 
 
 region of the spectrum. The second and third bands are 
 the most conspicuous of the set. 
 
 Solution in ether. — This gives the characteristic spectrum 
 exhibiting two bands of absorption. The solution is iri- 
 descent, but not enough so to be perceptible by common 
 observation. 
 
 The spectra of the solutions of purpurin in other solvents 
 might be mentioned, but these are more than sufficient. 
 From an optical point of view purpurin is remarkable for 
 the general similarity of character combined with diversity 
 as to detail, which its various solutions exhibit as to their 
 mode of absorbing light. 
 
 Alkaline solution of alizarin. — The solution of alizarin 
 in caustic or carbonate of potash or soda, or in ammonia, 
 exhibits on analysis a characteristic spectrum, having a 
 band of absorption in the yellow, and another narrower one 
 between the red and the orange. There is a third very in- 
 conspicuous band at E in the spectrum, almost lost in the 
 general darkening of that part. 
 
 Other solutions. — The solution of alizarin in ether or 
 bisulphide of carbon shows nothing particular. There is a 
 general absorption of the more refrangible parts of the 
 spectrum, but there are none of those remarkable alterna- 
 tions of comparative transparency and opacity which 
 characterise purpurin. Alizarin is hardly soluble in alum 
 liquor ; and in the case of the red solution, of mixed aliza- 
 rin and verantin, mentioned by Dr. Schunck at page 45 1 of 
 the Philosophical Transactions for 1S51, the absence of the 
 remarkable absorption bands and the absence of iridescence 
 show instantly and independently of each other that it is 
 distinct from purpurin. 
 
 Optical detection of purpurin and alizarin. — The characters 
 of these substances are so marked that I do not know any sub- 
 stance with which either of them could be confounded, even 
 if we restricted ourselves to any one of the solutions yield- 
 
DETECTION OF PURPURIN. 63 
 
 ing the peculiar spectra. Not only so, but these properties 
 enable us to detect small quantities, in the case of purpurin 
 the merest trace, of the substance present in the midst of a 
 quantity of impurities. In the case of purpurin a solution 
 of alum is specially convenient for use, because the impuri- 
 ties liable to be present do not, with this solvent, absorb the 
 part of the spectrum in which the bands occur. In this 
 way I was able, though operating on only a very minute 
 quantity of the root, to detect purpurin in more than twenty 
 species of the family rubiacece, which were examined 
 with this view, comprising the genera Rubia, Asperula, 
 Gallium, Crucianella, and Scherardia. The detection of 
 alizarin by means of the characters of its alkaline solution 
 is much less delicate, because many of the impurities liable 
 to be present absorb the part of the spectrum in which all 
 but the least refrangible of the absorption-bands occur ; and 
 as this band is not that which corresponds to the most in- 
 tense absorption, a larger quantity of the substance must 
 be present in order that the band may be perceived. 
 
CHAPTER III. 
 
 MADDER. — CONTINUED. 
 
 In the preceding chapter the colour-giving principles con- 
 tained in madder roots have been described, and also the 
 various compounds isolated from them by chemists, as well 
 as the artificial production of alizarin, which is the most 
 important of the latter. It will now be necessary to give a 
 brief account of Turkey red, and madder dyeing, and the 
 manufacture of the principal preparations of madder, such 
 as garancin, pinkoffin, fleurs de garance and the extracts 
 of madder. The various processes employed for obtaining 
 alizarin and purpurin on a commercial scale will then be 
 noticed, and lastly the methods employed for testing 
 madders and garancins. 
 
 The principal use of madder is to dye cotton cloth of dif- 
 ferent shades of red, of which by far the finest hue is that 
 called in this country and on the continent by the name of 
 Turkey or Adrianople red — one of the most durable colours 
 known. It seems highly probable that the method of dyeing 
 this tint — the characteristic of which consists in previously 
 impregnating the goods with an oily or fatty substance — 
 originated in India, where, as travellers affirm, the natives 
 have been wont, from time immemorial to steep the yarns 
 which they intend to dye in liquids containing fatty matter, 
 such for example as milk. It was not, however, until after it 
 had made its way into other parts of Asia, and become 
 known in the countries of the Levant, undergoing at the 
 same time important modifications, that this art was first 
 
 
TURKEY RED. 65 
 
 introduced into France, towards the middle of the last 
 century. In 1747, Messrs. Ferquet, Goudard, and D'Haristoy 
 brought a party of Greek dyers into that country, and formed 
 two establishments, one at Darnetal, near Rouen, and the 
 other at Aubenas, in Languedoc. Nine months later, a 
 person named Flachat, who had long resided in the Ottoman 
 Empire, brought over workmen with whom he formed at 
 St. Chamont, near Lyons, a third establishment for the dye- 
 ing of Adrianople red, so called from the high celebrity 
 then enjoyed by the productions of that city. But as these 
 foreigners could not long keep their art secret, they soon 
 had numerous imitators; and in 1765, the French govern- 
 ment, convinced of the value and importance of this method 
 of dyeing, made the processes known to the public. Many 
 establishments were formed in various parts of the country ; 
 but it appears that the only successful ones for some years 
 were those at Rouen. From these parts the Turkey red 
 dye gradually made its way into Alsace, Switzerland, 
 Great Britain, and different parts of Germany. At first 
 the cotton was only dyed in the yarn ; and it was not 
 until 1 8 10 that the cloth itself was dyed directly of this 
 colour at the establishment of Messrs. Kcechlin, Mul- 
 hausen, and that of L. Weber. 
 
 It is stated by the late Dr. Thomson, of Glasgow, and 
 other authorities, that the first Turkey red works in Great 
 Britain were established in that city about ninety years ago 
 by a M. Papillon. It appears, however, from a paper on 
 the art of dyeing, read before the Literary and Philosophical 
 Society of Manchester, by M. Thomas Henry in 1786, and 
 quoted by Mr. Baines in his History of the Cotton Manu- 
 facture, that M. Borelle, another Frenchman, introduced the 
 art of dyeing Turkey red at Manchester, probably some 
 years previous to its introduction at Glasgow, and that he 
 obtained from Government a grant for the disclosure of his 
 plans, as M. Papillon did afterwards from the commissioners 
 F 
 
66 DYEING AND CALICO PRINTING. 
 
 and trustees for manufactures in Scotland ; but the method 
 of the latter obtained the most decided success. It was in 
 the year 1783, that Mr. David Dale and Mr. George Macin- 
 tosh—father of the late Mr. Charles Macintosh, the inven- 
 tor of the well-known waterproof fabrics — engaged Papillon, 
 who was a dyer at Rouen, to settle in Glasgow, and he there 
 founded and carried on in partnership with Mr. Macintosh 
 the celebrated Turkey red business now conducted by the 
 firm of Messrs. Monteith and Co. The period having ex- 
 pired in 1803, when the process was to be divulged, the 
 commissioners and trustees above mentioned laid a com- 
 plete account of it before the public. Since that period 
 Turkey red dyeing has been conducted in Glasgow, and 
 also in Lancashire on a very extensive scale. 
 
 There are several processes followed for producing 
 Turkey red at the present time, but the operations are so 
 numerous, and success so much depends on matters of 
 detail in the carrying out of the various operations, that it 
 is impossible to describe with sufficient minuteness in a 
 work like the present all the precautions requisite to pro- 
 duce colours equal to those obtained by Messrs. Steiner 
 and Co., and several other firms in Manchester and 
 Glasgow. The following, however, is an outline of the 
 process : 
 
 A thousand pounds of calico are steeped in tepid water 
 for a day or two, to remove either by solution or fermenta- 
 tion the greater part of the size used for stiffening the 
 warp. This operation can be much shortened by adding a 
 small quantity of malt liquor to facilitate the transforma- 
 tion of the starch into glucose. The pieces are next boiled 
 in a keir, with a weak solution of carbonate of soda having a 
 specific gravity of I'OI, after which the goods are oiled by 
 padding them in a mixture of 580 lbs. of rancid Gallipoli 
 oil, or what is called by the French hnile toiimante, and 
 150 gallons of water in which is dissolved 10 lbs. of a mix- 
 
TURKE Y RED. 67 
 
 ture of potassium and sodium carbonate. To this mixture 
 some dyers still add sheep or cow dung, believing that the 
 azotised mucillaginous substance called by Morin bubulin, 
 materially contributes to the fixing of the fatty acids on 
 the fabric. The pieces are now exposed to the atmosphere 
 until they feel dry, when they are placed in a stove heated 
 to 140 F. After twelve hours they are taken out and the 
 padding operation repeated two or three times, according 
 to the intensity of the colour required. The pieces are 
 next steeped for twenty-four hours in a bath containing 
 carbonate of soda, to remove the fatty acids which have 
 not been fixed in the fibre. The liquid is pressed out, and 
 is called old white liquor. It is employed again in the 
 oiling operations. The goods are carefully rinsed out, and 
 are ready for the mordanting process, which consists in 
 passing the pieces at a temperature of 150 through a bath 
 composed of 30 gallons of water, 10 lbs. of ground gallnuts 
 or sumach, and 16 lbs. of alum. They are then hung for 
 two days in a stove, the temperature of which is maintained 
 at 140 R, and afterwards passed in a hot chalk bath. They 
 are then thoroughly washed and are ready for the dyebeck. 
 (Madder, which was formerly exclusively employed for this 
 work, is now almost entirely replaced by garancin and by 
 artificial alizarin.) The dyeing is performed by introducing 
 ten pieces into a beck containing 300 or 400 gallons of 
 water; 17 to 20 lbs. of madder, or 3 to 5 lbs. of garancin 
 for each piece are added and steam is introduced, the heat 
 being gradually raised during an hour and a half to 180 F., 
 it is then rapidly carried to near the boiling point and 
 maintained at that temperature for an hour. The pieces 
 are taken out, thoroughly washed by a washing machine, 
 passed a second time through the mordanting liquor, the 
 chalk bath, and the washing process, and again placed 
 in the dyebeck. The red thus produced is dark and dull, 
 as in the accompanying sample. 
 
68 DYEING AND CALICO PRIN1ING. 
 
 TURKEY RED AS DYED. 
 
 To brighten it, it is submitted to three clearing processes, 
 which are performed in closed boilers two-thirds filled with 
 water. For the first process about 6 lbs. of soap and 
 \y 2 lbs. of carbonate of potash are added, and the liquor 
 kept boiling for eight hours. 
 
 TURKEY RED AFTER FIRST CLEARING. 
 
 The pieces are again washed and boiled. This time with 
 6 lbs. of soap and 7 oz. of chloride of tin. After this pro- 
 
TURKE Y RED. 69 
 
 cess has been repeated, the goods are exposed for some 
 time to the atmosphere, passed through a hot bran bath, 
 washed, and dried. 
 
 TURKEY RED FINISHED. 
 
 We are indebted to the kindness of Messrs. Steiner 
 and Co., of Church, near Accrington, for these samples ol 
 Turkey red. 
 
 The same process is followed to produce Turkey red 
 upon yarn. Of late years, also, very fine purple-dyed 
 yarns have been produced by following the process above 
 described — but dipping the yarn in a solution of nitro- 
 sulphate of iron after the oiling processes. 
 
 Several chemists, among whom may be cited Persoz, 
 Schutzenberger, Kcechlin, and Jenny have tried to give a 
 rational explanation of the above operations, and to find 
 out why cotton treated by this method is dyed a red which 
 is faster and more brilliant than can be obtained by any 
 other process. One thing is certain, that fatty matters 
 are essential, and the 'oil must be in such a state that on 
 being mixed with carbonate of soda it will give an emul- 
 sion, or white milky fluid. An oil possessing this property 
 is called by the French /utile tournante. A sweet olive oil 
 
;o DYEING AND CALICO PRINTING. 
 
 does not produce an emulsion, and cannot be used with 
 advantage, but common Gallipoli gives* favourable results. 
 
 It is believed by many chemists and Turkey red dyers 
 that the oil must undergo a certain amount of oxidation, 
 and several patents have been taken out to effect this. It 
 is doubtful, however, whether oils treated by these pro- 
 cesses have to any extent replaced old Gallipoli. 
 
 It seems probable that the explanation given by Pelouze 
 in 1836 is the real one. He found that the oily matters 
 contained in a seed or berry could be kept sound for almost 
 any length of time if the seed were unbroken, but if it 
 were crushed, a peculiar ferment existing in the seed came 
 in contact with the fatty matters, and acting on them, 
 converted them into glycerin and fatty acids. He proved 
 that in the case of olives this change takes place in a 
 few hours after the berries are crushed, and that the 
 amount of free fatty acids is largely increased if they are 
 allowed to stand for any length of time. 
 
 The best qualities of olive oil are obtained by pressing 
 the berries, first at natural temperatures, and then between 
 hot plates, by this means the oil gets separated from its 
 ferment at once. At Gallipoli and the surrounding 
 country, the berries as soon as gathered are thrown into 
 heaps and allowed to ferment. By this process a much 
 larger yield of oil is obtained, but of inferior quality, owing 
 to its partial decomposition. 
 
 The correctness of these views is corroborated by the 
 fact that Mr. Steiner obtained very good Turkey reds, 
 when, at the suggestion of Pelouze he substituted for the 
 usual Gallipoli oil, oleic acid obtained in the manufacture 
 of stearin candles. 
 
 No doubt can remain that great progress is still being 
 made in the production of this class of goods, especially in 
 shortening the time required for the operations. At the 
 exhibition of 1867, M. Cordier, of Bapeaume, near Rouen, 
 
TURKE Y RED PRINT. 7 1 
 
 satisfied the jury that he could obtain a first-class Turkey- 
 red on cotton yarns' in five days. 
 
 Artificial alizarin is now being substituted for garancin 
 in the production of Turkey red, and some printers are 
 using large quantities of the artificial product. M. Armand 
 M tiller states that a red similar in tint and purity to Turkey 
 red may be obtained by direct printing with artificial 
 alizarin in the following manner. 
 
 The pigment, in a pasty form, and having 25 per cent, of 
 dry material, is dissolved in boiling spirit in the proportion 
 of one to five, and immediately mixed with a concentrated 
 solution of chloride of aluminium, of which the pure chlo- 
 ride is to the weight of the colouring matter as one to three. 
 The liquid is thickened with a little tragacanth, and for every 
 half litre of this mixture 30 cc. of a solution composed of 
 the best olive oil (fifteen parts), of sulphuric acid (one part), 
 and spirit (fifteen parts), is stirred in. This solution must be 
 as thin as possible, but must be thick enough to withstand 
 the capillarity of the cloth. The cotton cloth with which 
 this colour is to be used is first impregnated with a solu- 
 tion of acetate of alumina of about 8° Baume, and after 
 drying and two days ageing is taken through a soap bath 
 containing 30 grms. of Marseilles soap to the litre of 
 water, then well washed out and dried. 
 
 The cloth printed with the above mixture is now ex- 
 posed to strongly ammoniacal steam at a moderately high 
 pressure, taken through a weak soap bath, washed in a 
 stream, and taken through the following series of liquids : — 
 1. cold nitric acid, 3 cc. to 1 litre of water; 2. washed in 
 stream; 3. cold nitric acid, 5 cc. to 1 litre of water; 4. tin 
 salt, y 2 grm. to 1 litre of water at 90 F. ; 5. washed in 
 stream; 6. liquor of Javelle, 15 cc. of 8° Baume to 1 litre 
 of water, cold ; 7. thorough washing. The colour is now 
 thoroughly developed, and behaves to light, air, and soap 
 like ordinary Turkey red. In preparing the chloride of 
 
72 DYEING, AND CALICO PRINTING. 
 
 aluminium (by the addition of chloride of barium to sul- 
 phate of alumina), it is absolutely necessary to avoid an 
 excess of the barium salt. 
 
 The art of printing calico with madder was known to 
 the Egyptians and the countries of the East from time 
 immemorial, and we find on the fabrics wrapped round 
 some of the mummies designs in red and purple, which 
 have been produced by combinations of the colour-giving 
 principles of madder with alumina and iron mordants. 
 In Persia and India the art had attained a certain degree 
 of perfection, and up to the beginning of the 18th century 
 printed fabrics called chintz were imported from those 
 countries. A very heavy duty was, however, put on them 
 in 1700, and their importation entirely prohibited in 1720. 
 Although this was altered in 1774, a duty of 3^2 d. per 
 square yard was imposed on all printed calicos, whether 
 imported or made in England, and it was not until 1831 
 that this duty was repealed. Since that time there has 
 been a wonderful development of this manufacture ; 
 numerous mechanical improvements having been intro- 
 duced, and important chemical discoveries made. 
 
 Before proceeding with a description of the printing 
 process it will be necessary to give some idea of the com- 
 position of the mordants employed. Of course the 
 required intensity of shade is obtained by varying the 
 quantity of mordant. 
 
 For purples and lilacs an impure acetate of iron is 
 employed, which is prepared by allowing iron to oxidise or 
 rust, and then dissolving it in the tarry acetic or pyro- 
 ligneous acid obtained in the destructive distillation of 
 wood. 
 
 For reds and pinks a sulpho-acetate of alumina is em- 
 ployed, prepared by mixing together impure acetate of 
 lime and sulphate of alumina. If sufficient acetate of lime 
 were employed, the result would be that sulphate of lime 
 
MORDANTS. , 73 
 
 and acetate of alumina would be produced ; but the pro- 
 portions taken are such that only two-thirds of the 
 sulphuric acid combined with the alumina are replaced by 
 acetic acid; for experience has shown that better results 
 are obtained with this compound than with a pure acetate 
 of alumina. This mordant may be prepared by mixing 
 together solutions of one hundred and ninety-six parts of 
 sulphate of alumina and one hundred and thirty-six parts 
 of acetate of lime. In practice it is necessary to increase 
 the quantity of acetate on account of its being more im- 
 pure than the alumina salt. 
 
 For chocolate various proportions of red and black 
 mordants are mixed together, according to the shades 
 required. 
 
 The mordants are thickened with potato starch which 
 has been heated to 480 F. ; this renders it soluble, con- 
 verting it into dextrin, a substance somewhat similar in 
 properties to gum arabic. 
 
 The following recipes will give some idea of the pro- 
 portions taken : — 
 
 For light purple. 
 
 1 gallon of acetate of iron at i}4 T. 
 3 gallons of purple assistant liquor. 
 3 gallons of water. 
 18 lbs. roasted farina. 
 This solution is ready for use after straining. 
 
 For dark purple. 
 
 7 gallons acetate of iron at 2}i° T. 
 2<£ „ purple assistant liquor. 
 3 lbs. flour. 
 This mixture is first boiled and then strained, after which 
 it is ready for use. 
 
 The purple assistant liquor is made as follows : — 
 1 st. 100 gallons wood acid. 
 
74 
 
 DYEING AND CALICO PRINTING. 
 
 9 lbs. yellow prussiate of potash are dissolved in the wood acid. 
 
 2 gallons sulphate of lead precipitate, made by dissolving 
 acetate of lead in water, precipitating with sulphuric acid and 
 allowing the sulphate of lead to subside. 
 
 2nd. 50 lbs. carbonate of soda dissolved in 8 gallons of water, 
 to which is added 50 lbs. arsenious acid ; when this is dissolved 
 it is added to the first mixture, and thoroughly incorporated by 
 stirring. 
 
 To the above complete mixture, add 3 gallons of hydrochloric 
 acid and 200 lbs. of common salt. Mix well and store for use. 
 
 MADDER PURPLE. 
 
 For light red. 
 
 1 gallon acetate of alumina at 3 
 
 1 gill bark liquor at 1 2° 
 
 1 gill acetic acid. 
 $y 2 lbs. British gum. 
 
 Boil and strain. 
 
 For dark red. 
 
 1 gallon acetate of alumina at 12 T. 
 
 1 gill sapan liquor at 12 T. 
 
 1 y 2 lbs. flour. 
 
 Boil and strain. 
 
MORDANTS. 
 
 75 
 
 t 
 
 i 
 
 I 
 
 
 w* 
 
 I 
 
 MADDER PINK AND RED.* 
 
 For light chocolate. 
 
 
 
 
 2 gallons acetate of alumina at 
 
 9° 
 
 T. 
 
 
 . at 
 
 24° 
 
 T. 
 
 Y pint logwood liquor 
 
 . at 
 
 12° 
 
 T. 
 
 5 lbs. of flour. 
 
 
 
 
 Boil and strain. 
 
 
 
 
 For dark chocolate. 
 
 
 
 
 2 gallons acetate of alumina at 
 
 
 
 9 
 
 T. 
 
 Y2. gallon acetate of iron . . 
 
 . at 
 
 24° 
 
 T. 
 
 Y>. pint logwood liquor , 
 
 , at 
 
 12° 
 
 T. 
 
 5 lbs. of flour. 
 
 
 
 
 Boil and strain. 
 
 
 
 
 For blacks. 
 
 
 
 
 i gallon acetate of iron at 
 
 24° ' 
 
 r. 
 
 
 Y2 gallon wood spirit. 
 
 
 
 
 2Y2. gallons water. 
 
 
 
 
 1 pint logwood liquor at 1: 
 
 !° T. 
 
 
 
 7 lbs. flour. 
 
 
 
 
 Boil and strain. 
 
 
 
 
 * For the samples of madder purple and red we are indebted to the kindness 
 of Messrs. Symonds, Cunlifte, and Co. , of Manchester. 
 
7 6 
 
 D YEING AND CALICO PRINTING. 
 
 To apply these mordants they are placed in troughs in 
 which a copper roller dips, having engraved upon it the 
 design or pattern to be printed. The excess of mordant is 
 removed as it leaves the solution by means of a sharp 
 blade of steel, gun metal, or German silver, called a 
 doctor, leaving the mordant on the engraved parts only. 
 As the roller revolves, the calico to be printed is pressed 
 against it by another roller, and the mordant is thus 
 transferred to the cloth. The accompanying engraving 
 represents the kind of machine used. 
 
 Fig. i. 
 
 By an ingenious arrangement several rollers can be 
 mounted in the machine (as many as twenty have been 
 used), so that a piece may receive successively mordants 
 for different colours and of various strengths, which after- 
 wards produce the various tints and shades which the 
 
PRINTING MORDANTS. 77 
 
 printer may require. The accompanying sample due to 
 the courtesy of Messrs. Walter Crum and Co., of Man- 
 chester, will serve to illustrate the effect. 
 
 t HI * tl 4 
 *r * ^r * if 
 
 W *. "* * 1 
 
 * *r & * M 
 
 EFFECT PRODUCED BY A SIX-COLOUR MACHINE. 
 
 After this the pieces are passed over steam cylinders to 
 dry the mordant in the calico, and are subjected to a pro- 
 cess of ageing or fixing the mordant in the fibre. This 
 was formerly effected by spreading out the pieces, and 
 hanging them in a room for three or four days ; the acetate 
 of alumina thus lost part of its acetic acid, and the iron 
 mordant nearly the whole. Some few years ago, Mr. John 
 Thorn devised a method by which this could be effected in 
 twenty minutes; the process consists in passing the mor- 
 danted cloth over rollers fixed in a machine placed in a 
 chamber about 20 feet long, into which a current of air 
 and steam is thrown. The temperature must not be below 
 ioo° F. nor above 108 R, and the quantity of steam 
 present must be such that fifty yards of calico will take up 
 one ounce of moisture during the twenty minutes which it 
 requires to pass it through the chamber. The printer is 
 able to test the state of the chamber by means of wet and 
 dry bulb thermometers. 
 
78 
 
 DYEING AND CALICO PRINTING. 
 
 The next operation, called dunging, received this name 
 because formerly a mixture of cow dung and water was 
 used in the process. Now, however, the calico is generally- 
 passed through a weak bath of alkaline silicate or arseniate 
 of soda, mixed with a little chlorate of potash, contained 
 in a trough in which are fixed thirty or forty rollers in two 
 rows, one a,b, Fig. 2, at the top and the other c,d, at the 
 bottom. The cloth is slowly passed over the rollers from 
 top to bottom, alternately, the temperature being main- 
 tained at about mo F. 
 
 Fig. 2. 
 
 The objects of this process are, first, to effect the com- 
 plete decomposition of the aluminous and iron subsalts, 
 which are formed by removing the acid which the dessica- 
 tion has not expelled ; secondly, to dissolve and take away 
 from the stuff the greater part of the substances which 
 have been used to thicken the mordant; and, thirdly, to 
 separate from the stuff those parts of the mordant which 
 are not combined with it, which would otherwise spread 
 over and adhere to the unmordanted parts. 
 
 After this dunging the goods are washed and scoured in 
 the same way as in the bleaching process, in order to 
 remove everything which requires to be detached from the 
 fabric. 
 
MADDER DYEING. 79 
 
 Vj$ 
 
 ^1 
 
 
 ft 
 
 
 MADDER STYLE, MORDANTED CLOTH. 
 
 The mordanted pieces being now ready for the dyebeck, 
 five or six of them are placed on the reel for each of the 
 five or six compartments into which a dyebeck is divided, 
 so that from twenty-five to thirty-six pieces are dyed in 
 one operation. 
 
 The dyebeck is constructed as follows : — 
 
 A, Figs. 3 and 4, is a wooden or iron trough, about 6 feet in 
 length, 4 feet in width, and 4 or 5 feet in depth, into which 
 the madder and water required for a dyeing are introduced. 
 This vessel is surmounted with a wince or wheel B, and 
 divided in the direction of its length by four partitions b,b,b,b, 
 and thus presents five distinct compartments, into which 
 the goods fall on quitting the reel B. This reel, containing 
 six or eight wooden spars on its circumference, is furnished 
 at one end of its axis with pullies put in motion by 
 means of a strap driven by any moving power; it is always 
 moved by the hand in dyeing fine fabrics, such as muslins, 
 balzarines, &c. C,C,C,C, are wooden panels or lids with 
 hinges, to be opened and shut at pleasure. The upper two 
 open from below or upward, the lower two from above and 
 downward. D,E, are hollow copper rollers, under which 
 
8o 
 
 DYEING AND CALICO PRINTING. 
 
 the goods pass on quitting the compartments b,b,b,b. f is a 
 tube pierced with a multitude of holes, through which the 
 steam is introduced at pleasure by the tube h communi- 
 cating with a generator. A screw valve affords the means 
 of regulating the introduction of the steam into the tube/. 
 There is also a pipe in connection with a reservoir of water, 
 through which, by means of the stop-cock g,k, the quantity 
 of water required for the operation can be introduced into 
 the trough A. 
 
 Fig. 4. 
 
 The working of the apparatus is very simple; into each 
 compartment are put the requisite number of pieces ; after 
 passing the pieces over the wince and under the rollers D,E, 
 they are fastened together by the ends so as to form as 
 many endless webs as there are compartments. The pullies 
 are then set in motion, and the shaft of the reel being 
 in connection with them draws the goods in such a manner 
 that, passing out from under the cylinder D, they rise, pass 
 over the reel to fall back into the compartment b, slide 
 over the inclined plane, arrive again under the rollers D,E, 
 and so on during the whole operation. 
 
 The object of the compartments is to prevent the pieces 
 getting too much intermingled, as they would then cease 
 to obey the circulating movement and take the dye 
 unequally. 
 
MADDER DYEING. 8 1 
 
 The pieces are first introduced into the vats with cold 
 water, and from 5 to 7 lbs. of madder or ground Turkey- 
 roots per piece; the temperature is then gradually raised 
 in the course of an hour and a half to 180 F. 
 
 From the results of Schunck's experiments it would 
 appear that the effect of this is to give as much time as is 
 practically possible for the xanthin of Kuhlmann to unfold 
 into rubian and chlorogenin, and to allow the erythrozym 
 of the madder to decompose the glucoside or glucosides of 
 the madder into sugar, and alizarin or purpurin. If the 
 temperature were raised too rapidly the erythrozym would 
 become coagulated before it had time to effect the complete 
 decomposition of the glucosides. 
 
 The chlorogenin, pectic acid, rubiacin, verantin, rubi- 
 retin, &c, act very injuriously on the colours produced 
 from the madder, making them dull and weak and 
 the whites dirty. To obviate this a certain quantity 
 of chalk is added to the bath. The action of the 
 lime appears to be that it forms insoluble combinations 
 with these injurious colouring principles, and leaves the 
 alizarin to combine with the mordants. With Avignon 
 madder, this addition of chalk is unnecessary, for being 
 grown on a calcareous soil, it generally contains sufficient 
 lime naturally, whilst, on the contrary, it must always be 
 used with Turkey roots and Alsace madder. 
 
 That the action of the lime is as above stated, is shown 
 by the fact that when a proper proportion of chalk is 
 added the colours are not only brighter but are also more 
 permanent, whilst if an excess of chalk is employed the 
 strength and beauty of the colours are injured. The fact 
 was observed many years ago by Robiquet, and has recently 
 been confirmed by Schunck, that when a small amount 
 of lime is added to alizarin it proves injurious to the 
 intensity of shade produced by a given quantity of alizarin; 
 and Schunck proved also that the addition of rubiacin, or 
 G 
 
82 DYEING AND CALICO PRINTING. 
 
 any of the other resinous colouring matters, to alizarin 
 during the dyeing process produces very prejudicial 
 effects. They weaken the colours and render them 
 impure and unsightly ; the red acquires an orange, and 
 the purple a reddish hue, whilst the blacks become 
 brownish, and the white parts assume a yellow tinge. 
 These effects entirely disappear as soon as the foreign 
 colouring matters are completely saturated with lime. 
 On the contrary, Rosenstiehl* states that perfectly pure 
 alizarin, with distilled water, dyes but very imperfectly ; 
 and that, in order to obtain satisfactory results, it is abso- 
 lutely necessary that a certain quantity of carbonate of 
 lime should be present. 
 
 In the preceding chapter it was stated that erythrozym 
 was a compound containing lime, and that if this lime 
 were once removed the erythrozym became inactive and 
 permanently altered; it is important, therefore, that lime 
 should be added, to prevent the free acids acting injuri- 
 ously on this compound. 
 
 Having thus briefly noticed the changes which take 
 place in the hour and a half during which the temperature 
 is gradually raised, we will return to the description of the 
 dyeing process. Full steam is now turned into the beck so 
 as to heat the liquor as near 21 2° F. as practicable. The 
 effect of this, as shown by the table of solubility of alizarin 
 already given, is to increase the amount of alizarin in solu- 
 tion, and thereby facilitate its combination with the 
 mordant. When the dyeing is completed the pieces are 
 removed from the beck, and thoroughly washed in a wash- 
 ing machine. 
 
 Compt. Rend., lxxix., 6So. 
 
MADDER STYLE. 
 
 83 
 
 MADDER STYLE AFTER DYEING. 
 
 The fifth operation is the soaping, to remove the excess 
 of colour and clear the whites ; the becks used being 
 similar to those employed for dyeing. A sufficient amount 
 of soap of good quality is dissolved to produce a perceptible 
 froth, and the goods, arranged as for dyeing, are kept 
 constantly revolving on the reel. The temperature of the 
 beck is maintained at 180 F. They are then taken 
 out, thoroughly washed, and subjected to a second 
 soaping. After another thorough washing, the pieces are 
 passed through a slightly alkaline hypochlorite of soda 
 solution, to which is added a little sulphate of zinc. 
 
 
 ^ 
 
 
 i- 
 
 
 i $ 
 
 
 
 
 1 ■ .. 
 
 
 m k 
 
 11 J 
 
 311 
 
 raft Z 
 
 Si I 
 
 ■ 
 
 
 
 :•>.-' k 
 
 \t§, s 
 
 :; 
 
 i.> P 
 
 
 
 
 i E j 
 
 ?r 
 
 1 
 
 ■s 
 
 1 
 
 
 MADDER STYLE CLEARED.* 
 
 * Messrs. Symonds, Cunliffe, and Co., of Manchester, have kindly furnished 
 the three specimens of madder style. 
 
84 DYEING AND CALICO PRINTING. 
 
 Some twenty years ago, whilst professionally engaged 
 in a printworks, the author made a series of experiments 
 with a view of decreasing the serious expense involved in 
 employing such large quantities of soap in the above 
 operations, and found that madder goods could be steeped 
 even for days without injury in a decidedly alkaline solution 
 of hypochlorite of soda, prepared by making a neutral 
 hypochlorite of soda, and adding an ounce of crystallised 
 carbonate of soda per gallon, and that by employing this 
 solution such a quantity of the chlorogenin and resinous 
 compounds already described were removed, that one soap- 
 ing operation could be dispensed with. 
 
 The difficulty and expense experienced by calico 
 printers in brightening their colours and obtaining pure 
 whites in madder-dyed goods, attracted many years ago 
 the attention of scientific and practical men, and any pro- 
 cess by which these difficulties might be overcome was 
 anxiously looked for. The discovery by Robiquet and 
 Colin, that the colour-giving principle was not destroyed 
 by sulphuric acid, was the first step in that direction, and 
 led Schwartz to observe that the carbonaceous mass of 
 Robiquet might, if carefully washed and neutralised, be 
 used as a dyestuff. Messrs. Lagier and Thomas improved 
 upon this, and in 1839 introduced an article which is now 
 extensively used by calico printers under the name of 
 garancin. It is generally prepared in the following 
 manner : Madder is treated with eight or ten times its 
 weight of water and allowed to stand for twelve hours. 
 This liquor is then run off and reserved for treatment in a 
 manner similar to that obtained in the manufacture of 
 flcurs de garance which will be described further on. The 
 washed madder is introduced into large wooden vats lined 
 with lead, and a quantity of water added sufficient to 
 make the whole into the state of a thin paste. 35 lbs. 
 of sulphuric acid are now added for every 100 lbs. of 
 
MANUFACTURE OF GARANCIN. 85 
 
 madder originally taken. The vat is then closed and the 
 madder steamed for several hours,* after which it is 
 mixed with a large quantity of cold water and run off into 
 a vat with a false bottom of woollen, where it is washed 
 methodically with water until the latter takes a slightly pink 
 hue ; this is an indication that all the acid has been 
 removed. Some manufacturers to save time add a small 
 quantity of carbonate of soda to the last washing liquor, 
 and Messrs. Dollfus, Mieg, and Co. have suggested the 
 employment of ammoniacal vapours to effect the same 
 purpose. The garancin is placed on trays in a chamber 
 where it is submitted to the action of the ammonia. They 
 state that their ' garancine modifiee ' gives much richer 
 and brighter colours, and that the purples are especially 
 improved. When the garancin has been thoroughly 
 washed, it is placed in centrifugal machines to drive off the 
 water as far as possible and is then submitted to hydraulic 
 pressure. The pressed cakes thus obtained are put in 
 drying stoves, and when quite dry are ground with mill- 
 stones and sieved. 
 
 The attention of the French government having been 
 called to the pollution of the rivers which receive the 
 washing liquors of the garancin manufacturers in the 
 neighbourhood of Avignon, they were called upon to 
 devise some method of abating this nuisance, as it had 
 increased to such a degree as to endanger the health of 
 the inhabitants, and to cause great injury to the land- 
 owners. 
 
 M. Pernod, one of the largest manufacturers of garancin 
 and fleurs de garance in the department of Vaucluse, gave 
 the subject his attention, and contrived a process by which 
 he not only removed nearly the whole of the organic 
 matter in suspension and neutralised the acid, but even 
 
 * Stenhouse has observed that a large quantity of a compound called furfurol 
 is produced during this operation. 
 
S6 DYEING AND CALICO PRINTING. 
 
 effected a saving, for he discovered that the spent liquor of 
 garancin contains a large quantity of oxalic acid. In his 
 process the whole of the spent liquor of a day's working is 
 run into a large reservoir, and slacked lime is added to it 
 in slight excess. After two or three hours, the clear liquor 
 which may now be considered unobjectionable, is run off 
 into the river. The lime deposit after being pumped up 
 into smaller reservoirs and mixed with a slight excess of 
 dilute sulphuric acid is allowed to stand for twelve hours, 
 when the liquor -is run off and the precipitate thrown on a 
 woollen filter. This precipitate, which consists of sulphate 
 and oxalate of lime mixed with a small quantity of colour- 
 ing matter, is boiled in a leaden vessel with an excess of 
 sulphuric acid ; this decomposes the oxalate of lime, sul- 
 phate of lime is formed, and the liberated oxalic acid 
 dissolves in the acid liquor. It is filtered through flannel 
 whilst hot, and on cooling deposits a large quantity of 
 oxalic acid in the crystalline state. 
 
 One hundred parts of madder yield from thirty-four to 
 thirty-seven of garancin, according to the variety of madder 
 used. Turkey roots are usually employed to prepare first- 
 class garancins for purples and lilacs, French madders and 
 Naples roots for pinks and reds, and Dutch madders for 
 dark reds and chocolates. Twenty million pounds weight 
 of madder are annually employed in the neighbourhood of 
 Avignon for the manufacture of garancin. 
 
 The dyeing power of a good garancin is from four to five 
 times as great as that of the madder from which it is made. 
 The gain, therefore, apart from the greater purity of colour 
 in the garancin, is from 70 to 85 per cent, on the original 
 madder. This increased dyeing power is due to the com- 
 plete decomposition of the rubian and other glucosides the 
 root may contain, and possibly also to the liberation of a 
 certain quantity of colour-giving principles which may be 
 combined with the lime and magnesia present. 
 
GARANCIN STYLE. gy 
 
 For garancin style only 1% to 3 lbs. of garancin are 
 employed per piece. The dyeing operation is conducted 
 in a manner very similar to that of madder styles, except 
 that the temperature of the beck never exceeds 1 8o° F. 
 
 The advantages of garancin over madder are, that the 
 goods dyed with it require only a slight soaping and 
 passing through a clearing liquor of very weak alkaline 
 hypochlorite of soda and a little sulphate of zinc, for the 
 goods to be ready for the stiffening and calendering pro- 
 cesses. On the other hand the colours are not so fast, for 
 they will not resist the action either of light or of soap to 
 the same degree as madder-dyed goods. Moreover, the 
 colours, except the purples, are far less brilliant; and, 
 although the addition of a little chalk to the bath in the 
 dyeing process tends, by neutralising the traces of acid 
 which commercial garancin usually contains, to improve 
 the colours obtained, yet there is still a marked inferiority 
 to madder. The following illustration of the garancin style 
 has been kindly furnished by Messrs. Wood and Wright, 
 of Manchester. 
 
 GARANCIN STYLE. 
 
 In 1852, Messrs. Schunck and Pincoffs effected an im- 
 provement in the manufacture of garancin, their product 
 
88 DYEING AND CALICO PRINTING. 
 
 being known in England under the name of 'commercial 
 alizarin'; but on the continent it is better known as 
 1 pincoffin.' Their process consists in submitting 
 
 ordinary garancin to the action of high-pressure steam of 
 a temperature of 300 F., which, whilst it does not act on 
 the alizarin contained in the garancin, destroys the rubi- 
 retin and verantin. The employment of commercial 
 alizarin is especially advantageous in the production of 
 purples, which are faster and more brilliant than those 
 produced by ordinary garancin. The cloth also does not 
 require soaping or clearing. 
 
 DYED WITH 'COMMERCIAL ALIZARIN.' 
 
 We are indebted to the kindness of Mr. S. Pincofifs for 
 this sample dyed with 'commercial alizarin.' 
 
 In 1843, M- Leonard Schwartz, of Mulhouse, patented 
 the right of treating spent madder from dyebecks by the 
 same process as that employed for the conversion of 
 madder into garancin. To the product so obtained he 
 gave the name of garanceux. At the present day this 
 process is carried out by every large madder dyer. 
 
 Messrs. Julian and Roquet have devised a process for 
 preparing a purified madder which they call fieurs de 
 
FLEURS DE GARANCE. 89 
 
 garance, or flowers of madder, of which many million 
 pounds per annum are now manufactured in France. It 
 not only yields brighter colours than the original madder, 
 but as it does not soil the white parts of prints, its use 
 saves the printer much soap and labour. It possesses also 
 another great advantage. The printer can obtain the same 
 intensity of shade by employing mordants about fifteen 
 times weaker than when madder in its original 'state is 
 employed. This is owing to the fleurs de garance no 
 longer containing any soluble matters, especially acids like 
 pectic acid, &c, which during the process of dyeing 
 dissolve and remove such a large proportion of the 
 mordant. 
 
 To prepare the fleurs de garance, madder is mixed with 
 eight or ten times its bulk of water and allowed to stand for 
 twelve to fifteen hours. When Avignon madders are used 
 and the fleurs are intended for the production of reds or 
 pinks, one part of sulphuric acid for every hundred of roots 
 is added to the water to neutralise the carbonate of lime 
 which that madder always contains. This addition of 
 acid is unnecessary when Alsace and Dutch madders are 
 used, or when the fleurs are intended for the production of 
 purples or chocolates. When the maceration is finished 
 the liquor is run off into proper vessels to be fermented, so 
 as to transform the sugar into alcohol. The solid matter 
 is placed in bags, submitted to hydraulic pressure, and 
 after being dried in stoves and ground, is ready for use. A 
 hundred parts of madder yield fifty-five to sixty o{ fleurs de 
 garance. It may be stated en passant, that the injury 
 which Dutch and Alsace madders sustain when kept too 
 long in casks, is doubtless owing to the fact that after the 
 erythrozymic fermentation is completed, an alcoholic and 
 lactic one sets in, which acts injuriously on the colour- 
 giving principles. 
 
 The alcohol prepared by the fermentation and distilla- 
 
go DYEING AND CALICO PRINTING. 
 
 tion of the liquids obtained in the above process has a 
 very disagreeable taste and odour, and is only fit for 
 manufacturing varnishes and ether, and for other commercial 
 operations. This seems to be caused, to some extent at 
 least, by the presence of acetic ether and aldehyde, in fact 
 the latter substance may be easily obtained from madder 
 alcohol by careful rectification. At Sorgues, near Avignon, 
 there is a large distillery where the greater part of the 
 alcohol produced in the manufacture of fleurs de garance 
 and garancin is rectified. The method employed appears 
 to consist in passing the alcohol vapours through wood 
 charcoal. 
 
 Various extracts of madder are prepared on a large 
 scale, all of which contain alizarin or purpurin in a more or 
 less pure form. They are applied in a different manner to 
 those preparations hitherto noticed, being printed on along 
 with the mordant, and then dried and submitted to dry 
 high-pressure steam for one or two hours, when the colours 
 become fixed on the fabric. 
 
 Calico printers have long desired to obtain these ex- 
 tracts, and although many chemists and printers have 
 worked on the subject, among whom may be mentioned 
 Persoz, Claubry, Fauquet, Girardin, Gerber, Dollfus, 
 Verdeil, Michel, and Schiitzenberger, yet they have failed 
 in introducing this class of product into the trade. This 
 result is no doubt generally to be attributed to their im- 
 purity, although several extracts, especially those of Messrs. 
 Fauquet and Girardin and M. A. Hertmann have been 
 employed. Their use, however, was confined to single 
 firms, and in these only to a limited extent. 
 
 The house of Messrs. Scheurer, Roth, et Fils, of Than, 
 were the first to successfully apply these extracts ; the pro- 
 ducts employed being Kopp's purpurin and green alizarin, 
 prepared by Messrs. Schaaff and Lauth, of Strasbourg. 
 M. Leitenberger also used an extract manufactured by M. 
 
MADDER EXTRACTS. 91 
 
 Brosch, of Prague, who followed a process discovered by 
 Rochleder, but which is kept secret. M. Pernod's extract 
 was also soon after in use, and the splendid specimens 
 exhibited at the Paris Exhibition in 1867 by the two firms 
 above mentioned, and several other Alsace houses, could 
 leave no doubt of the success of these products. 
 
 The printing of the colour-giving principles of madder 
 on fabrics must be considered as the greatest improvement 
 in calico printing since the introduction of coal tar colours, 
 and there can be scarcely any doubt but that it will in 
 time completely revolutionise the trade. 
 
 If we compare the length of time, the amount of trouble, 
 and the numerous processes required to produce by the 
 ordinary method a piece of printed madder goods — the 
 printing of the mordant, the ageing, the dunging, the dyeing, 
 once or twice soaping and clearing, and the thorough 
 washing between each of the last four operations — with the 
 simple process of printing the colour, steaming, washing, 
 and soaping, the truth of this statement will at once be 
 evident. 
 
 The process of M. Leitenberger, is based on the fact 
 that purpurin is soluble in water at 130 F., whilst alizarin 
 only dissolves at 170 F. He mixes madder with water 
 and heats the whole gradually by means of a jet of steam 
 to 1 30 F., at which temperature it is maintained for some 
 time. The liquor is then run off and filtered, and the 
 operation is repeated until the madder ceases to yield any 
 soluble matters. To the clear solution, lime, or still better, 
 baryta is added, when a lake precipitates, which is collected, 
 washed, and mixed with hydrochloric acid. The purpurin 
 thus liberated is thrown on a filter and washed, when it is 
 ready for use. The madder remaining from the above 
 operation is dried and heated with wood spirit in closed 
 vessels to extract the alizarin. The operation is repeated 
 until no more alizarin is dissolved. This extract is slowly 
 
92 DYEING AND CALICO PRINTING. 
 
 poured into water, care being taken to agitate well ; a 
 hydrate of alizarin is thus precipitated, which, according to 
 M. Leitenberger, is less soluble than alizarin itself. This 
 when collected and washed is ready for use. 
 
 Another process is that patented by Mr. Paraf, in 
 December, 1868. He avails himself of the extraordinary 
 increased solubility of alizarin in water at high tempera- 
 tures, mentioned in the preceding chapter. He has devised 
 an apparatus by which he is able to treat madder with 
 water under a pressure of four or five atmospheres, and 
 when the liquor is saturated to draw it off from the solid 
 matter remaining in the apparatus. As the aqueous liquor 
 cools, the alizarin separates in the form of flocks, which, 
 when collected and washed, are ready for use as an extract. 
 He finds that the solubility is increased by adding a small 
 quantity of alum or sulphuric acid to the water employed 
 in the operation. 
 
 A third process, that of M. Emile Kopp, is based on 
 Schunck's discovery that weak acids act in a similar manner 
 to erythrozym in causing the rubian to split up into sugar 
 and alizarin. Kopp observed, some years ago, that a solu- 
 tion of sulphurous acid dissolved the glucosides of purpurin 
 and alizarin without change; and he has since applied this 
 observation to the development of the following elegant 
 process for the preparation of alizarin and purpurin: — 
 600 lbs. of Alsace madder are macerated for twelve or 
 fifteen hours, with 800 gallons of a weak solution 
 of sulphurous acid, to which is added one-thousandth part 
 of hydrochloric acid to neutralise the earthy carbonates 
 existing in the root. This operation is repeated three 
 times. To the liquors 3 per cent, of sulphuric acid is 
 added, and the whole heated to a temperature not 
 exceeding 140° R, when red-coloured flakes separate and 
 gradually deposit ; these when washed and dried are com- 
 mercial purpurin. The clear liquor after being boiled for 
 
A'OPP'S PURPURIN AND ALIZARIN. 93 
 
 a couple of hours and allowed to cool, deposits a dark 
 green powder, which when washed and dried is known as 
 'green alizarin.' 
 
 Kopp has still further improved upon this process, which 
 he devised in 1856, and instead of obtaining commercial 
 purpurin and green alizarin he is able to produce an 
 alizarin which he calls alizaric extract, so pure that it can 
 be used for printing purples and lilacs, and a second 
 which is used for printing reds, pinks, and chocolates. By 
 employing methodic lixiviation and modifying his mode of 
 operation, he has also been able to save the saccharine 
 matter existing in the madder and to convert it into 
 alcohol. 
 
 To prepare the alizaric extract for purples and lilacs, 
 one part of green alizarin is boiled with fifteen or twenty 
 parts of petroleum oil, having a boiling point not exceed- 
 ing 300 R, which dissolves the alizarin and leaves the green 
 matter, probably chlorogenin. After a quarter of an hour's 
 ebullition it is left to stand for a few minutes, in order to 
 allow the green matter to settle, which it does rapidly. 
 The clear liquor is then poured off and allowed to cool to 
 212 R, when a certain quantity of nearly pure alizarin is 
 deposited in the form of small yellow crystals. The 
 supernatant liquid is mixed with 10 or 15 per cent, of an 
 aqueous solution of caustic soda, containing 5 to 8 per 
 cent, of soda, and the whole strongly agitated. The alka- 
 line solution takes out the whole of the alizarin, and when 
 decanted and rendered slightly acid with dilute sulphuric 
 acid deposits the colouring matter as a crystalline mass. 
 This is fit for use as soon as it has been collected and 
 washed ; it is sold under the name of yellow alizarin. 
 
 To prepare the extract for pinks and reds, the madder 
 which has been exhausted by sulphurous acid to obtain 
 purpurin and green alizarin, is introduced into bags and 
 subjected to hydraulic pressure. It is then placed in vats 
 
94 DYEING AND CALICO PRINTING. 
 
 and lixiviated with a weak solution of caustic soda ash 
 (i to \]/ 2 percent); being gradually heated to boiling. The 
 alkaline liquor which contains the colouring matter, pectic 
 acid, fatty matters, resins, &c, is removed into large vats, 
 and is there mixed with the acid liquors from which the 
 purpurin and green alizarin have been separated, in such a 
 proportion that the liquor has a distinctly acid reaction. 
 An abundant gelatinous precipitate is thus produced, 
 which, when collected, washed, and dried, is called pectic 
 extract, and can be employed for dyeing purposes. To 
 prepare an extract sufficiently pure for printing, the gela- 
 tinous precipitate is mixed with an acid solution of 
 sulphate of alumina, marking 4' to 6° Baume, and contain- 
 ing 4 to 6 per cent, of free acid. The mixture is then 
 boiled for fifteen or twenty minutes and filtered rapidly. 
 As the filtered liquor cools orange flakes are deposited, 
 which are collected and mixed with ten or fifteen times 
 their volume of water, containing from 5 to 8 per cent, of 
 sulphuric acid. The whole is kept at a temperature of 
 1 95 F. for an hour, allowed to cool, and the mass thrown 
 on a filter and washed first with acidulated water and then 
 with pure water. There remains a beautiful orange magma 
 sold under the name of orange extract of madder. It is 
 employed for printing chocolates as well as reds and 
 pinks.* 
 
 This manufacture has been carried on by Messrs. Schaaff 
 and Lauth for several years, and doubtless yields a larger 
 amount of colour-giving principle than M. Leitenberger's 
 method, for the glucosides must be more completely 
 decomposed in these processes than by water alone. 
 
 The dyeing power of alizarin thus obtained is equal to 
 forty times its weight of madder, and ten times its weight 
 of garancin. 
 
 *For full details and the description of the preparation of alcohol from 
 the residue, see Bulletin Societe Industrielle de Mulhouse, xxxvii., 437. 
 
PERNOD' S EXTRACTS. 
 
 95 
 
 It is to the kindness of Messrs. Dollfus, Mieg, and Co. 
 that the author is indebted for the accompanying beautiful 
 specimens of these colours, which have been obtained with 
 the products manufactured with so much skill by Messrs. 
 Schaaff and Lauth. 
 
 Another extract is that manufactured and patented by 
 M. Pernod. It is largely used at the present time in 
 Lancashire as a topical colour.* His process consists in 
 exhausting garancin by methodical lixiviations with, boil- 
 ing water, containing five parts per thousand of sulphuric 
 acid. As the acid liquor cools an orange-red precipitate 
 falls to the bottom of the vat, which is collected and 
 washed until entirely free from acid : this is readily ascer- 
 tained, as the washing water assumes a pinkish hue 
 immediately the last trace of acid is removed. The 
 
 * This term is applied to a colour which is printed on a fabric and after- 
 wards fixed by the action of steam. 
 
96 DYEING AND CALICO PRINTING. 
 
 extract so obtained is exhausted by boiling alcohol in a 
 properly constructed apparatus, in order to dissolve out 
 the colouring matter. The alcoholic extract is mixed with 
 one quarter its bulk of water, introduced into a retort, and 
 the alcohol recovered by distillation. The residue remaining 
 in the retort is thrown on a filter and washed with water, 
 when it is ready for use. 
 
 The last process which it is necessary to notice, although 
 perhaps not so practicable as those previously given, is yet 
 interesting in itself, being probably the first case in which 
 bisulphide of carbon was employed for extracting colours. 
 According to this method, which was patented by M. 
 Alfred Rien, in February, 1870, dry fleurs de garance, 
 or garancin, are placed in suitable closed vessels with 
 heated bisulphide of carbon. The liquor is run off whilst 
 hot, and the sulphide of carbon is removed by distillation. 
 The residue left in the retort is dissolved in weak alkali, 
 and the colouring matters precipitated by the addition 
 of sulphuric acid in quantity sufficient to exactly neutralise 
 the soda. The floculent precipitate of alizarin and pur- 
 purin after being washed is ready for use. 
 
 The following recipes may prove useful, as they show 
 the proportions necessary to produce the various shades. 
 
 For dark reds. 
 
 Take 8 lbs. of extract of madder, 
 4 lbs. of acetic acid, and 
 i}( lbs. of starch. 
 Boil these in an earthenware vessel, and when cold add to six 
 measures of the above one of acetate of alumina, and a very 
 small quantity of Gallipoli oil — say one per cent. 
 
 For a pink. 
 
 Take 4 lbs. of extract of madder. 
 2 lbs. of acetic acid. 
 10 quarts of gum Senegal water. 
 1 pint of acetate of alumina. 
 
PRINTING WITH MADDER EXTRACT 97 
 
 For a purple. 
 
 Take 1 pint of extract of madder. 
 y 2 pint of acetic acid. 
 Yz pint of water. 
 3 oz. starch. 
 Boil, and when the mixture is cool add 5 oz. measure of acetate 
 of iron at 24 T., and 5 oz. water. 
 
 For a chocolate proceed as in the last recipe, substituting 
 acetate of chromium for acetate of iron. 
 
 For a red. 
 Boil together 2 litres of (Pernod's) extract in paste. 
 1 y 2 litres of acetic acid at 8° Baume. 
 448 grammes of olive oil. 
 After boiling, the acid which has evaporated is replaced, and 
 the mixture is thickened with 1,500 grammes of gum Senegal in 
 powder. 
 
 When the colour is required for use, to the above mixture is 
 added J^ a litre of acetate of alumina at 15 Baume. It is 
 important to add the mordant with care and just before use, other- 
 wise the combination of the mordant with the colouring matter 
 takes place before the printing, and there is considerable loss of 
 the latter. 
 
 For dark purple. 
 Boil together 1 litre of extract (Pernod's) in paste. 
 1 litre of acetic acid at 8° Baume. 
 224 grammes of olive oil. 
 The acid which is evaporated is replaced, and the mixture is 
 thickened with 600 grammes of powdered gum Senegal. When 
 required for use there is added 
 
 224 grammes of black mordant at io° Baume. 
 128 grammes arsenite of soda at 6° Baume. 
 
 A second is, 
 
 Take 9 litres extract (Pernod.) 
 
 8 litres acetic acid at 8° Baume. 
 20 litres gum water of 1,000 grammes of 
 gum per litre of water. 
 2 litres black mordant at io° Baume. 
 H 
 
93 DYEING AND CALICO PRINTING. 
 
 If the dry extract of Rochleder be employed, the quantity must 
 be calculated on the basis of five parts of Pernod's being equal to 
 one of Rochleder's. 
 
 After the cloth is printed the pieces are hung to dry for a 
 certain time, then submitted to the action of dry high-pressure 
 steam for an hour and a half or two hours. 
 
 Schiitzenberger states that pure alizarin gives very 
 beautiful purples, but the reds have a violet shade. The 
 best reds he considers are obtained with extracts contain- 
 ing both purpurin and alizarin, and a certain proportion of 
 yellow colouring matter. On the other hand, these 
 extracts give only dull purples. 
 
 Up to the time of the introduction of printing the 
 extracts, chocolates were obtained with madder by 
 means of a mixture of iron and alumina salts. It 
 was, however, found difficult to produce fine shades by 
 this mixture in printing, and Mr. Horace Kcechlin made 
 a series of experiments to ascertain whether any of the 
 other metallic oxides could be employed with the extract 
 of madder to produce some new and useful shades. He 
 prepared acetates of twenty-two metals, and made a mix- 
 ture of each with Pernod's extract thickened with gum. 
 After printing these mixtures on the fabric and steaming 
 it for two hours, he obtained the following results : — 
 
 Silver Rose. 
 
 Antimony Yellowish rose. 
 
 Bismuth Bright rose 
 
 Barium Dirty shade. 
 
 Calcium Bright rose. 
 
 Cadmium Bright rose. 
 
 Copper Bright rose. 
 
 Chromium Chocolate. 
 
 Cobalt Bright rose. 
 
 Tin Red. 
 
 Glucinum Red. 
 
PRINTING WITH MADDER EXTRACT. 99 
 
 Magnesium 
 Mercury- 
 Manganese 
 Molybdenum 
 Gold 
 Platinum 
 Palladium 
 Lead 
 
 Tungstate of Soda 
 Uranium 
 Zinc 
 
 Bright rose. 
 
 Bright rose. 
 
 Bright rose. 
 
 Bright rose. 
 
 Bright rose. 
 
 Grey violet. 
 
 Olive shade of the oxide. 
 
 Rose yellow. 
 
 Rose yellow. 
 
 Grey or drab. 
 
 Rose. 
 
 From these results he concluded that the only two 
 metallic oxides which could be used with marked advan- 
 tage in connexion with these were the oxides of uranium 
 and chromium, the former for greys and the latter for 
 chocolates. Acetate of chromium is now used in the trade 
 for the production of chocolates, and the following is the 
 recipe given by M. Spirk : — 
 
 Take 2 litres (Pernod's) extract in paste. 
 
 2 litres acetic acid at 7 Baume. 
 
 3 litres acetate of chromium at 1 7 Baume. 
 
 For the following sample, which represents the effect 
 obtained with chromium acetate, we are indebted to the 
 kindness of M. K. Koechlin, of Alsace. 
 
 CHROMIUM MORDANT. 
 
IOD 
 
 DYEING AND CALICO PRINTING. 
 
 To obtain the uranium grey the following proportions 
 are employed : — 
 
 2 litres extract of madder in paste. 
 
 2 litres acetic acid at 7 Baume. 
 
 3 litres acetate of uranium at io° Baume. 
 
 URANIUM GREY. (k. KOECHLIN.) 
 
 The following recipes are used with success in printing 
 with artificial alizarin. It is delivered in two forms, pure 
 or in paste containing 10 per cent. The recipes are for 
 the latter. 
 
 For a red. 
 Take 2,500 grammes alizarin. 
 
 8,000 grammes thickening. 
 500 grammes acetate of alumina at io° Baume. 
 250 grammes chalk at 16 Baume. 
 The red is obtained by adding one part of this mixture to two 
 parts of thickening, then printing and steaming. It is afterwards 
 passed through a bath heated to 120 or 140 F., and composed 
 of 1,000 litres of water, 30 kilos, of chalk, and \y 2 kilos, of 
 chloride of tin, or 20 kilos, of chalk and 5 kilos, of arseniate 
 of soda ; it is then brightened. 
 
 The thickening is made of 6 kilos, of starch, 20 litres of water, 
 % litre of acetic acid, 10 litres of gum tragacanth (2 ounces of 
 gum per litre), and of 1 "5 kilos, of olive oil. 
 
 The following is another recipe : — 
 4 or 5 kilos alizarin. 
 10 litres thickening. 
 300 to 400 grammes nitrate of alumina at 15 Baume. 
 
 (prepared from nitrate of lead and alum). 
 600 grammes acetate of alumina at io° Baume. 
 400 to 500 grammes acetate of lime at 16 Baumd 
 
ARTIFICIAL ALIZARIN. 101 
 
 The use of nitrate of alumina gives a red of a more orange 
 shade than is obtained with the acetate. 
 To produce purple. 
 
 Take 1,400 grammes alizarin. 
 10 litres thickening. 
 200 grammes black mordant at 12 Baume. 
 370 grammes acetate of lime at 1 6° Baume. 
 The thickening is formed of 5 kilos, starch, 18 litres water, 
 9 litres gum tragacanth, 3 litres acetic acid at 6° B., and 1 kilo, of 
 olive oil. 
 
 The printed fabrics are steamed under a pressure of half an 
 atmosphere for twenty-four hours. They are then passed for two 
 hours in a bath of arseniate of soda (5 kilos, arseniate, 20 kilos, 
 chalk, and 1,000 water) at 120 to 140 F., washed and brightened 
 in a bath of soap (3 kilos, of soap to twenty pieces of fifty yards). 
 
 TOPICAL STYLE WITH ARTIFICIAL ALIZARIN. 
 
 One of the most serious objections to the use of madder 
 as a topical colour, has been the small amount of colour 
 fixed, compared with the quantity used, and consequently 
 the great loss which occurs in the washing, after steam- 
 ing. We are therefore much indebted to Messrs. Scheurer, 
 Roth, et Fils, of Alsace, for publishing the following simple 
 process for its recovery : — 
 
 The pieces are washed in a beck containing chalk or 
 
102 DYEING AND CALICO PRINTING. 
 
 gelatinous alumina, which takes up the colour as it comes 
 off the cloth and prevents it soiling the whites. 
 
 When the washing liquor in the beck is sufficiently- 
 charged with the colouring matter, the matters in suspen- 
 sion are allowed to settle, and the deposit thrown on a 
 filter. It is then removed from the filter and mixed with 
 weak sulphuric acid if alumina has been employed, or 
 hydrochloric acid, if lime. The mineral matters and gum 
 or starch are dissolved, leaving the colouring matter in an 
 impure state. This is washed, dissolved in a weak solution 
 of soda, filtered, and on the addition of an acid the colour- 
 giving principles are precipitated, and after washing are 
 ready for use. 
 
 There is another source of loss also for which M. Carlos 
 Kcechlin has devised a remedy. The acetic acid employed 
 in the mordants is found to act rapidly on the doctors of 
 the printing machine when they are made of steel. The 
 iron thus dissolved combining with the colouring matters 
 of the extracts soon dims the brilliancy of the reds, pinks, 
 and chocolates produced by an alumina or chrome 
 mordant. The troughs must consequently be emptied, 
 and the colouring principles are recovered as follows : — 
 
 For every 12 quarts of refuse printing liquor containing 
 ]/ 2 lb. of Pernod's extract 4 quarts of concentrated 
 sulphuric acid are added and the whole heated for two 
 hours in a water bath. The insoluble matter is then well 
 washed and is equal in every respect to the original extract. 
 
 The waste soap liquors which are produced in such large 
 quantities in the clearing of madder-dyed and printed 
 goods, if allowed to run into rivers not only pollute the 
 stream, but as they contain a considerable amount of 
 colouring matter, there is also a loss of valuable material. 
 Messrs. Thorn and Stenhouse, in July, 1872, took out a 
 patent* for the recovery and utilization of this soap waste 
 
 *No. 2,186. 
 
RECOVERY OF SOAP WASTE. 103 
 
 in the following manner : A solution of chloride of 
 calcium is run into the soap liquors in a large cistern until 
 no further precipitation takes place, and milk of lime is 
 then added so as to render the solution decidedly alkaline ; 
 for this purpose about 43 lbs. of quicklime are required for 
 every 20,000 gallons of the soap liquor. After thoroughly 
 mixing and allowing it to stand for twelve hours, the clear 
 liquor, which is almost colourless, is drawn off, and the 
 precipitate is pumped into a smaller cistern, where it is 
 treated with hydrochloric acid in quantity just sufficient to 
 decompose the lime soap. The liberated fatty acids, and 
 the colouring matter which exists as a lake, are collected 
 on woollen filters and pressed at first cold, and then under 
 hot water ; by this means nearly all the fat is squeezed 
 out. The pressed cake is then treated in a properly con- 
 structed apparatus with light petroleum to dissolve and 
 remove the last traces of fat from the valuable colouring 
 matter, which is finally boiled with dilute sulphuric acid, 
 and washed with cold water until free from acid in a 
 manner similar to that practised in making garancin. The 
 colouring matter thus obtained is equal in dyeing power 
 to three or four times its weight of the best garancin. 
 
 The preparation of madder lake, which is used in oil and 
 miniature paintings, for colouring artificial flowers, &c, may 
 now be briefly described. It is equally permanent with 
 the colours fixed on fabrics, and is consequently much 
 prized by the painter. 
 
 There have been several processes proposed for its 
 preparation, but the two following by M. Persoz appear 
 to be the best : — 
 
 Madder washed with water containing sulphate of 
 soda is boiled for twenty minutes with ten times its 
 weight of a solution of alum, containing one part of alum 
 in ten of solution. It is filtered and allowed to cool to 
 90 or ioo° F. The red liquor may then be treated by two 
 
104 DYEING AND CALICO PRINTING. 
 
 methods. By the first it is cautiously saturated with 
 carbonate of soda, say one-eighth or a tenth, according to 
 the amount of alum employed, by which a basic alum is 
 formed, which remains in solution. The liquor is now 
 boiled and an insoluble subsulphate of alumina is precipi- 
 tated, which is combined with all the colour in the bath. 
 The precipitate is not gelatinous, but separates and filters 
 rapidly. It also dissolves easily in acetic acid. By the 
 second method seventy-eight parts of acetate of lead for 
 one hundred of the alum employed are added to the liquor, 
 on which there is a precipitate of sulphate of lead. The 
 red liquor is filtered and boiled, when the colouring matter 
 is precipitated in combination with the insoluble basic 
 sulphate of alumina. The lake obtained by the latter 
 process is much purer, and the colour more intense than 
 that obtained by the carbonate of soda process. 
 
 Instead of employing madder in the above preparations, 
 it is more convenient to use either the extracts, or, perhaps 
 best of all, commercial purpurin, which is at present 
 little used in dyeing. 
 
 The last point to be considered in relation to madder 
 and its preparations, is the determination of its compara- 
 tive value. 
 
 It is easy to understand that a dyestuff so high in price 
 as madder offers great inducement to the dishonest dealer 
 for adulteration. For this purpose both mineral and organic 
 substances are used, among which may be enumerated : — 
 Mineral Matters. Organic Substances. 
 
 Powdered brick. Oak sawdust. 
 
 Ochre. Mahogany sawdust. 
 
 Yellow sand. Various ground dyewoods. 
 
 Yellow clay. Fustic. 
 
 It is easy to ascertain if it has been adulterated with any 
 mineral substance, as on incineration good madder yields 
 only from 9 to 1 1 per cent, of ash, and if the amount ex- 
 
TESTING MADDER. 105 
 
 ceeds this it will indicate that it has been adulterated with 
 some inorganic matter. 
 
 To determine the amount of extraneous matter of an 
 organic nature is not so easy. One of the best methods is 
 to compare the dyeing power of the suspected sample with 
 madder of known good quality. 
 
 This is effected by placing twelve grains of each of the 
 samples to be compared in pans of copper or block tin 
 with a quart of water. These pans are placed in a water- 
 bath heated by means of a jet of steam. A piece of calico 
 mordanted with red, purple, and chocolate mordants which 
 cover about three-fourths of the surface of the cloth is 
 placed in each pan. It is important that each strip taken 
 should be about three inches in breadth, and its length equal 
 to one-half the breadth of the calico (twenty-six inches). 
 The swatches are placed in the pans whilst cold ; steam is 
 then turned on, and, as in practice, the temperature is gradu- 
 ally raised during an hour and a half to 180° F., and then for 
 half an hour kept as near the boiling point as possible. 
 During the whole time of the operation the pieces should be 
 constantly and carefully lifted out of the dyeing liquor, either 
 with a glass rod, or better still by a mechanical arrangement. 
 When the dyeing is completed, the pieces are thoroughly 
 washed with pure water and the brilliancy and intensity of 
 shade carefully compared. If the samples under trial are 
 found to be weaker than the standard, the dyeing opera- 
 tion is repeated, adding such a quantity of the inferior 
 madder as will bring up the colour to the same intensity 
 as the standard. The values are in inverse ratio to the 
 quantities taken : thus, if it requires eighteen grains of 
 the sample under examination to give the same depth of 
 colour as twelve grains of the standard sample, it has only 
 two-thirds the dyeing power. 
 
 A further trial is, however, necessary to arrive at a cor- 
 rect conclusion as to the value. The dyed pieces are 
 
106 DYEING AND CALICO PRINTING. 
 
 divided into two parts, one of which is kept for a com- 
 parison, whilst the other is submitted to a light soaping; 
 three or four grains of soap to one quart of water being 
 sufficient for the surfaces above given. They are carefully- 
 heated in this solution for half an hour, the temperature 
 being kept at i8o p F. They are then washed and dried, 
 and the tints again compared. 
 
 The first operation gives the total amount of colour; the 
 second removes any colouring matter of the dyewoods, 
 such as sapan and peachwoods, which may have been used 
 for the purpose of adulteration, leaving nothing on the 
 cloth but the madder colours. 
 
 The author had several instances of adulteration by 
 dyewoods, during his long experience in Manchester, but 
 the most difficult case which came under his notice 
 occurred some years ago. Several samples of madders 
 were submitted to him, whose dyeing power was so inferior 
 that undeniably some adulteration had been practised ; still, 
 the amount of ash was right, and no foreign dyewood could 
 be detected. After a great number of experiments it was 
 ascertained that they had been mixed with spent madder. 
 
 Garancin and fleurs de garaiice are tested in the same 
 way, but eight grains only are taken, and the specimens 
 are only heated to 1 8o° F. 
 
 The extracts containing much more colouring matter 
 than madder or garancin, it is better to use six inches of 
 cloth in place of three, and two quarts of water, taking 
 only two grains of the extract. 
 
 With Dutch and Alsace madders it is necessary to make 
 a second trial, adding i or 2 per cent, of chalk to neutral- 
 ise the acids naturally present and to combine with the 
 injurious colouring principles. 
 
 Garancins also are often not sufficiently washed. It is 
 necessary, therefore, to ascertain if they are perfectly neu- 
 tral, and if not, to add chalk in this case also. 
 
TESTING MADDER. 107 
 
 In the case of garancins, fleurs de garance, and extracts, 
 if the operation has been properly conducted, the whites 
 will be clear without soaping. If they are not satisfactory, 
 they may be cleared by heating with water containing 10 
 per cent, of bran for about ten minutes at 1 8o° F. 
 
 M. Pernod, a few years ago, published a very simple and 
 practical method for ascertaining if a sample of garancin or 
 madder is adulterated with sapan or peachwood, logwood, 
 fustic, or valonia or other tannin matters. 
 
 His process consists in dipping a sheet of paper in a 
 weak solution of bichloride of tin, and another in persul- 
 phate of iron. These papers are each placed on a plate 
 and the suspected sample sprinkled over them. If any of 
 the woods are present, the tinpaper gives with sapan or 
 peachwood, crimson ; with logwood, purple ; and with 
 fustic or bark, yellow spots. The iron paper gives, with 
 logwood, black; and with valonia or any other tannin 
 matter, dead black spots. 
 
 To ascertain if the reds, pinks, purples, or chocolates on 
 a piece of calico are derived from madder, the following 
 tests may be applied. 
 
 1. A small piece of the fabric is calcined. If it is a madder 
 red or pink it will leave a white ash of alumina, soluble in 
 concentrated sulphuric acid. The solution thus obtained 
 when diluted with water yields a white gelatinous pre- 
 cipitate on the addition of ammonia. 
 
 If it is a madder purple it will leave a reddish residue, 
 soluble in hydrochloric acid, and containing iron ; the solu- 
 tion when diluted will give a blue precipitate with potas- 
 sium ferrocyanide (yellow prussiate). Madder chocolates 
 will yield an ash of an ochre colour from which the iron 
 may be dissolved by treatment with hydrochloric acid, and 
 if the residue be heated with concentrated sulphuric acid 
 and the solution diluted, it will give the characteristic tests 
 for alumina. If the chocolates yield a green ash, chromium 
 
io8 DYEIXG AND CALICO PRINTING. 
 
 has been used. If the ash be fused with borax before the 
 blowpipe it will yield a green bead, and with nitrate of 
 potash it will form potassium chromate. This on being 
 dissolved in water will give a bright orange or yellow pre- 
 cipitate with salts of lead. 
 
 2. If a piece of the dyed cloth be dipped in a solution of 
 bleaching powder it will be decolourised, but if carefully 
 washed and placed in a bath containing madder and 
 gradually heated the original colour will reappear. 
 
 3. If dipped in hydrochloric acid the colour on the 
 cloth assumes an orange hue, which in contact with milk of 
 lime becomes changed to purple. It will stand passing 
 through a weak soap bath at 1S0 F. This character may 
 be observed with reds and chocolates as well as with 
 purples. 
 
 Garancin work gives all the above characters, but the 
 colours will not stand a rather strong soap solution. 
 
 The properties of the colouring principles of madder 
 have been somewhat fully described, as well as the methods 
 employed in rendering them available for dyeing fabrics, 
 because these colours have been so long known, are so 
 durable, so extensively employed, and so interesting from 
 a scientific point of view. The rubia tiiictorum, however, 
 is not the only species of rubiactz which yields fast colours 
 with the ordinary mordants, or even with cloth oiled, as in 
 the Turkey red process. There are two other important 
 dyestufifs obtained from this natural order, namely, munjeet 
 and cJiayavcr, which may be briefly described here. 
 
 It is to the researches of Dr. Stenhouse that we are in- 
 debted for the information we possess on the colouring 
 matters of munjeet or rubia munjista. This peculiar variety 
 of the genus rubia is cultivated exclusively in Asia, and 
 especially in India, where it has been used as a dyestuff 
 from a remote period, either alone or mixed with other 
 dyes, to produce a variety of red shades. It is imported 
 
MUNJEET. 109 
 
 into this country from time to time, but has never been 
 very extensively used, as the colours produced from it are 
 neither so bright nor so fast as those obtained with the 
 nrtria tinctorum. 
 
 Whilst the colouring principles of madder are purpurin 
 and alizarin, those of munjeet are purpurin and a yellow 
 colouring matter, named by Dr. Stenhouse, munjistin. 
 C 8 H O 3 . This latter body, which in some specimens is 
 present only in very small quantity, crystallises from its 
 alcoholic solution in beautiful golden-coloured scales: when 
 slowly sublimed it forms golden scales and broad flat needles 
 of great beauty. It is only slightly soluble in cold, but freely 
 in hot water. It gives with caustic soda a rich crimson 
 colour. Alumina removes it entirely from its aqueous 
 solution, and the orange-coloured lake so formed com- 
 municates to soda the crimson colour above mentioned. 
 
 To obtain the colouring matter from the munjeet, one 
 part of the finely powdered root is boiled for four or five 
 hours with two of sulphate of alumina and sixteen of 
 water. The red liquor thus obtained is strained through a 
 cotton cloth and hydrochloric acid added; as the liquid 
 cools a bright red precipitate is thrown down. This is 
 collected on a filter, well washed, dried, and treated with 
 bisulphide of carbon, which dissolves the colour-giving 
 principles, thus separating them from the dark-coloured 
 resinous impurities. When the bisulphide is distilled off 
 it leaves a residue consisting of purpurin and munjistin, 
 from which the latter may be dissolved out by treating it 
 with boiling water. On the addition of hydrochloric acid 
 to the aqueous solution the munjistin is separated in orange- 
 coloured flocks. This precipitate is collected and dissolved 
 in alcohol, which when concentrated by distillation yields 
 the munjistin in a crystalline state; after two or three 
 crystallisations, it is quite pure. 
 
 According to Mr. Higgin, the munjeet root yields from 
 
no DYEING AND CALICO PRINTING. 
 
 52 to 55 per cent, of a garancin, which has only 
 half the dyeing power of the garancin made from mad- 
 der. It cannot, therefore, be used with advantage for 
 this purpose. 
 
 The inferiority of munjeet arises from its containing 
 only the comparatively feeble colouring matters, purpurin 
 and munjistin. Munjeet is not much used by calico 
 printers, as the munjistin, when present, gives a brownish- 
 purple with salts of iron, which prevents it being employed 
 with that mordant. It is principally used for special 
 shades of Turkey red. 
 
 Munjeet is an excellent source of pure purpurin as it 
 contains no alizarin, but only a mixture of purpurin and 
 munjistin, the latter of which can easily be removed by 
 thoroughly washing the purified mixture of colouring 
 matters with boiling water. After this treatment, one or 
 two crystallisations from boiling spirit yield pure purpurin 
 in deep crimson needles. In the mixture of colouring 
 matters obtained from madder, on the contrary, the pur- 
 purin is associated with alizarin and various other sub- 
 stances from which it is a matter of extreme difficulty to 
 separate it in a pure state. 
 
 The chayaver is not used in Europe, owing to its only 
 containing one-fourth of the amount of colour-giving 
 principle which can be obtained from madder roots, but it 
 is extensively cultivated and used on the coasts of Malabar 
 and Coromandel, to obtain red colours on cloth oiled in a 
 similar manner to that employed for Turkey red. Chalk 
 is added to the dyebeck, which is heated at first to about 
 ioo° F. for some time, and afterwards carried to the boil to 
 fully develope the colour. The brilliancy of the colour is 
 brought out by heating the goods in a weak soap solution 
 in closed vessels. 
 
 This root gives. all the colours obtainable with madder, 
 and like madder colours, they can stand soaping. 
 
SOORANJEE. ill 
 
 Koechlin and Schuuck find; that alizarin can be easily 
 extracted from this root by means of alcohol. 
 
 Two more varieties of rubiaceae are also used in the East, 
 one of which bears the name of nona, the other is called 
 ouongkondou ; the former is very acid, and contains a 
 large quantity of a yellow colouring matter. 
 
 The last source of the colouring principles of madder 
 which will be mentioned is the morinda citrifolia, the 
 'Al' root, or Sooranjee of the Hindoos, who employ it 
 in a Turkey red process. The fabric is steeped in an 
 emulsion of sesam oil, exposed to the air, and then dyed 
 with the pulverised root. This plant is extensively used 
 as a dyestuff in the Madras Presidency. Whilst munjeet 
 contains purpurin but no alizarin, this plant contains 
 alizarin but no purpurin. ^^^^^dU^X^^^^ . 
 
 In 1829, Anderson examined this root, and obtained 
 from it a pale yellow crystalline body, which he called 
 morindin. This compound on distillation yields a reddish- 
 yellow crystalline sublimate, to which he gave the name of 
 morindone. Stenhouse has since examined these com- 
 pounds, and the results he has obtained are contained in 
 the following note.* 
 
 "In 1852, Professor Rochleder, from the consideration 
 "of Anderson's statement, gave it as his opinion, that 
 "morindin was identical with the ruberythric acid which he 
 "himself had obtained from madder, and that morindone 
 "was alizarin. About eighteen months ago I was fortunate 
 "enough to obtain a very small quantity of 'Al' root, from 
 "which I extracted the morindin by Anderson's process. 
 "When cautiously heated in a Mohr's apparatus, it was 
 "decomposed, yielding a sublimate of bright yellowish-red 
 "needles, which had all the physical and chemical proper- 
 ties of alizarin. tv^VVv^6vM., 
 
 "When powdered morinda root is boiled with moderately 
 
 * Jour. Chem. Soc, xvii,, 333. 
 
112 DYEING AND CALICO PRINTING. 
 
 "dilute sulphuric acid, as in the ordinary garancin process, 
 "its morindin is converted into alizarirr; but the large 
 "quantity of brown resinous matter which is produced at 
 "the same time, very greatly diminishes the value of the 
 "dyestuff obtained, for it renders the colours dull and 
 "the whites very difficult to clear. Although ' Al ' root is 
 "therefore never likely, at least in Europe, to compete 
 "successfully with madder, still it furnishes the scientific 
 "chemist with the best known source of pure alizarin; 
 "for, as is well known, it is by no means easy to separate 
 "the last trace of purpurin, which always accompanies 
 "alizarin in ordinary madder." 
 
CHAPTER IV. 
 
 RED DYEWOODS, SAFFLOWER, AND ALKANET. 
 
 RED DYEWOODS. — In this chapter an entirely different 
 class of red, purple, and black colours will be described, 
 which, although like madder derived from the vegetable 
 kingdom, are obtained not from the roots of an herbaceous 
 plant, but from the stems of trees which attain a consider- 
 able size; they are known in commerce under the name 
 of dyewoods. These have been very extensively used for 
 a considerable time, and although the brilliant shades of 
 the coal-tar colours have in some measure superseded them 
 in certain branches of dyeing, yet the rapid increase of the 
 dyeing trade has prevented any diminution in the actual 
 amount imported into and used in this country. 
 
 LOGWOOD. — The first, both in importance and in order 
 of the time of its introduction, is campeachy or logwood, 
 which is obtained from a large tree of the leguminous 
 family, called by the botanist Hcematoxylon campcchiivmm, 
 growing abundantly in the West Indies, Mexico, and other 
 States of South America. The finest wood was formerly 
 imported from the bay of Campeachy, in the gulf of Mexico, 
 but as this source of supply is now almost exhausted, the 
 best commercial qualities are at present obtained from 
 Jamaica and St. Domingo, whilst Honduras, Martinique, 
 and Guadaloupe furnish woods of inferior quality. 
 
 Campeachy wood was introduced into Europe by the 
 
 Spaniards, but it was not until the reign of Elizabeth that 
 
 it came into use in England, and then only for a short 
 
 time; for upwards of a century its employment was for- 
 
 I 
 
ii 4 DYEING AND CALICO PRINTING. 
 
 bidden under the most severe penalties, on the grounds that 
 the colours it produced were fugitive and easily injured by- 
 weak acids and by the action of the atmosphere. About 
 the fourteenth year of the reign of Charles the Second, 
 however, these penalties were repealed, for it had been 
 found that by the use of various species of tannin the 
 stability of the logwood colours was much increased and 
 their brilliancy heightened. 
 
 On the appointment of M. Chevreul to the post of pro- 
 fessor of chemistry to the Gobelins, that eminent chemist 
 turned his attention to the study of the various colouring 
 matters and colour-giving principles of the dyestuffs. 
 Among the first to engage his attention was logwood, in 
 which (in the year 1810) he discovered a crystalline sub- 
 stance of a yellowish-white colour, having a prismatic form, 
 and becoming rapidly coloured on exposure to the atmo- 
 sphere, especially if a trace of ammonia were present. He 
 gave to it the name of Jicematin. Erdmann, in 1842, ex- 
 amined it further, and changed the name to hematoxylin, 
 by which it is now generally designated. It is only slightly 
 soluble in cold water, to which it communicates a bitter 
 sweet taste. It is more soluble in hot water, and is readily 
 dissolved by alcohol, ether, and bisulphide of carbon. It 
 combines with three molecules of water, forming a 
 crystalline hydrate, which at 21 2° F. still retains one 
 molecule. The formula of these compounds may be 
 thus expressed : — 
 
 Hematoxylin C 10 H 14 O . 
 
 Crystalline hydrate C 10 H u O c , 3OHL 
 
 Monohydrate C 10 H u O G , OH 2 . 
 
 Hematoxylin assumes a beautiful purple colour when ex- 
 posed to the action of oxygen, especially in the presence of 
 alkalis, being converted into a compound called hasmatein. 
 
 Erdmann prepared this product by saturating ammonia 
 
H& MATE IN. 115 
 
 with hematoxylin, and leaving the solution exposed to the 
 air for some time; the liquor assumed a dark cherry-red 
 colour, and gradually yielded small crystals, which he called 
 hemateate of ammonia. On decomposing this compound 
 with acetic acid a bulky brownish-red precipitate was 
 obtained, which on desiccation acquired a metallic greenish 
 lustre. 
 
 Hemateate of ammonia may be obtained in four-sided 
 microscopic prisms of a violet-black colour, which lose their 
 ammonia at 212 F. 
 
 Erdmann finds that hematein prepared by this process 
 is more soluble in alcohol than in water or ether, and that 
 when dissolved in ammonia and left in contact with the air 
 it becomes brown, and at last nearly black, showing that 
 hematoxylin may undergo several degrees of oxidation. 
 
 Rcun , who has recently studied this substance, states 
 that it may be obtained in crystals by exposing to the air 
 an ethereal solution of hematoxylin, to which a small 
 quantity of concentrated -sulphuric acid has been added. 
 After some time brownish-red crystals are deposited on the 
 sides of the vessel containing the liquid. These must be 
 collected and washed with ether. The crystals are soluble 
 in hot water, which on cooling solidify to a gelatinous 
 mass ; this, on the evaporation of the water, leaves amor- 
 phous scales, having a cantharides green lustre. These 
 scales dried in the air give, on analysis, results correspond- 
 ing to the formula C 1C H 12 G +3OH0. The crystals dried 
 in vacuo have the composition C 1G H 12 G + OH 2 , and when 
 dried at 212 F. C 1G H 12 G . . 
 
 This compound cannot be recrystallised from an. alco- 
 holic solution; ammonia and the other alkalis colour it a 
 fine violet-blue. It can easily be reconverted into hema- 
 toxylin by boiling its solution with sulphurous acid, or 
 with zinc and sulphuric acid, or by the action of sulphu- 
 retted hydrogen. 
 
n6 DYEING AND CALICO PRINTING. 
 
 The following equation represents the manner in which 
 the hematoxylin is converted into haematein by oxidation : 
 
 C,,H u 6 + O = C 1G H 12 O c ,OH 2 . 
 Hematoxylin. Haematein. 
 
 When perfectly pure, hematoxylin is quite white, and 
 readily enters into combination with the alkalis. A colour- 
 less barium compound may be obtained, which, however, 
 rapidly becomes purple on contact with oxygen, as do also 
 the potash and soda salts; this effect is due to the con- 
 version of the hematoxylin into haematein. 
 
 The oxidation and consequent colouration of hematoxy- 
 lin, under the influence of alkalis, is so rapid that it may 
 be used as a most delicate test for the presence of carbo- 
 nate of lime in natural waters ; and it is a fact well known 
 to practical dyers that water containing a large quantity of 
 carbonate of lime is well adapted for the production of 
 logwood blacks, not only because it accelerates the oxida- 
 tion of the iron mordant and the fixing of it on the tissue, 
 but also because it facilitates the oxidation of the hema- 
 toxylin and consequently its conversion into haematein, the 
 former giving little or no colouration with salts of the pro- 
 toxide of iron, whilst the latter gives a dark purplish-blue. 
 
 -Reun found that the action of caustic potash on hema- 
 toxylin gives rise to pyrogallic acid. Four parts of potash 
 and one of hematoxylin are fused together until the mass 
 acquires a brown colour; the product is dissolved in water, 
 neutralised with dilute sulphuric acid, filtered, and agitated 
 with ether. On evaporating the ethereal solution a syrupy 
 residue is left, which yields a crystalline sublimate of pryo- 
 gallic acid when submitted to distillation. The occurrence 
 of this benzene derivature and others closely allied to it, 
 in the products of the action of caustic alkalis on many 
 of the colouring matters, shows an intimate connection 
 between them. 
 
 Mr. Sorby has given, in the proceedings of the Royal 
 Society, vol. xv., the characters which the various colours 
 
REACTIONS OF HEMATOXYLIN. 
 
 117 
 
 present when examined with the spectroscope; but, as the 
 paper bears on the analysis of colours generally, it will be 
 preferable to give a resume of it under that head, rather 
 than describe the spectrum of each colour, as it passes 
 under our notice. 
 
 Logwood yields but a small amount of colouring matter 
 to cold water, and to boiling water only about 3 per cent. 
 With distilled water the decoction has only a pale yellow 
 tint, and with a calcareous one a blood-red colour. The 
 whole of the haematoxylin, however, can only be removed 
 with difficulty by means of water, but alcohol and ether 
 dissolve it with facility. Large prismatic crystals of the 
 colouring matter are often found at the bottom of casks 
 in which logwood extracts have been kept for a consider- 
 able time. An aqueous solution of haematoxylin gives the 
 following reactions : — 
 
 The colour changes to yellow. 
 The colour changes to red. 
 [ Becomes yellow and is then 
 1 decolourised. 
 r Colour it of a reddish-purple, 
 \ which becomes violet more 
 L or less tinted with blue. 
 Blue precipitate. 
 Colour the liquid purple or 
 
 Weak acids 
 Concentrated acids 
 
 Sulphuretted hydrogen 
 
 Soluble alkalis 
 
 Lime water 
 
 Neutral salts of magnesia, 
 
 lime, or baryta 
 
 Alum 
 
 Bichromate of potash 
 
 Salts of lead 
 
 \ 
 
 violet. 
 
 First becomes yellow, gradu- 
 ally changing to wine colour 
 and violet, and then gives a 
 purple precipitate. 
 
 Black colouration. 
 fVeiy dark violet precipitate, 
 more blue than red by reflec- 
 ted light, and more red than 
 blue by transmitted light. 
 
n8 DYEING AND CALICO PRINTING. 
 
 Chloride of tin Violet or blue precipitate. 
 
 Salts of iron Bluish-black precipitate. 
 
 Salts of copper Dark-blue or violet precipitate. 
 
 Salts of zinc Dark reddish-purple precipi- 
 
 Salts of gold Orange precipitate. [tate. 
 
 Chloride of mercury Orange-red precipitate. 
 
 Nitrate of bismuth Magnificent violet precipitate. 
 
 It is highly probable that the colour-giving principle 
 exists in Hamatoxylon Campecliianum, in the state of a 
 glucoside, for when the trees are felled the wood is colour- 
 less ; but by the time the logs arrive in this country the 
 outside is of a dark red colour, whilst the inside is only 
 pale yellow. This is no doubt due to the hematoxylin 
 glucoside being partially decomposed, and the hema- 
 toxylin being converted into hematein on that portion of 
 the wood exposed to the air. As it is the latter substance 
 the dyer requires, it is necessary to effect the complete 
 decomposition of the glucoside, and the oxidation of the 
 hematoxylin. The plan adopted is to rasp the logs as 
 imported into a coarse powder, and after moistening it, to 
 lay it in beds 15 to 20 feet long, 10 to 12 feet broad, 
 and about 3 feet thick. A slow fermentation ensues, 
 during which the glucoside is decomposed and the hema- 
 toxylin liberated. The beds are frequently turned, both 
 to allow the air to act on the hematoxylin and to 
 prevent the fermentation proceeding too rapidly, or the 
 heap from getting too warm, in which case the colouring 
 matter would be completely destroyed. The ammonia 
 liberated from the azotised principles of the wood during 
 the fermentation no doubt greatly facilitates the formation 
 of the colour. 
 
 Logwood thus prepared is used not only directly by the 
 dyer to produce logwood blacks, but also to prepare an 
 extract much used in calico printing and woollen dyeing. 
 
LOGWOOD EXTRACT. 1 19 
 
 To obtain a good extract it is important that the powder 
 should not be too highly oxidised, and that the solu- 
 tions obtained by repeated lixiviations should be slowly 
 concentrated at a comparatively low temperature, that is 
 to say not exceeding 150 F., for if a high temperature be 
 employed the hssmatein undergoes further change, and is 
 converted into a dark purple resinous principle, which 
 spoils the brilliancy of the colour and of course materially 
 decreases the value of the extract. For this reason many 
 printers prefer to use the decoction, which they make as 
 they require it, and it is doubtless on this account that the 
 dry extracts of logwood which have from time to time 
 been imported into this country have had so little success. 
 One of the best methods of concentrating the liquid con- 
 sists in evaporating the decoction of the logwood on a 
 double copper cylinder, 4 or 5 feet in diameter, and 
 heated by steam ; this, which dips into a trough containing 
 the extract, is kept slowly revolving. By this means a 
 large surface for evaporation is obtained, whilst the 
 temperature can be kept at the low point which is essential 
 for the production of a good extract. 
 
 To produce purples and violets, in steam styles, the cloth 
 is passed through a solution of stannate of soda, and after- 
 wards through a bath of dilute sulphuric acid; or first 
 through a solution of oxymuriate of tin, and then through 
 a dilute alkali bath, by which means stannic oxide or bin- 
 oxide of tin is separated and fixed as a mordant in the 
 fibre of the cloth. After the fabric has been washed and 
 dried, a strong solution of logwood thickened with starch 
 is printed on it, and it is again dried by passing over steam 
 cylinders. It is now either rolled on a perforated cylinder 
 and submitted to the action of high-pressure steam, or 
 hung in an iron chamber and steamed at a low pressure, 
 when the hsematein combines with the oxide of tin, pro- 
 ducing a beautiful purple. 
 
120 
 
 DYEING AND CALICO PRINTING. 
 
 LOGWOOD PURPLE. 
 
 For the production of blacks the fabric is printed with 
 pyrolignite of iron, exposed to the atmosphere and treated 
 in a manner similar to that employed for fixing the iron 
 mordant for madder, which has been already described. 
 It is then patfcted in a logwood solution, and the black 
 afterwards fully developed by passing it through a hot 
 dilute solution of bichromate of potash. 
 
 LOGWOOD BLACK. 
 
 Logwood and its extract are also much used in York- 
 shire for producing cheap blacks on mixed fabrics, that is, 
 
BRAZIL WOOD.—PEACHWOOD. 121 
 
 goods in which the warp is cotton and the weft woollen. 
 The fabric is dyed in a bath composed of logwood, sulphate 
 of soda, and bichromate of potash ; and the black so pro- 
 duced is the fastest that can be obtained with logwood ; 
 part of the oxygen of the bichromate oxidises the colour- 
 ing principle, and the sesquioxide of chromium which is 
 thus produced becomes fixed on the fabric and acts as a 
 mordant. 
 
 Besides being used for dyeing blacks, as above stated, it 
 is also employed to produce greyish purples with salts of 
 alumina. It is likewise extensively used for dyeing silk 
 and leather as well as for cotton and wool. 
 
 Brazil, Peach, Sapan, and Lima Woods. — All these 
 woods are obtained from trees of the genus Cmalpinia, 
 belonging to the natural order Legnminosce. They are 
 imported into this country in sticks or logs, varying con- 
 siderably in size, of a dark red colour externally, but 
 nearly colourless in the interior; they have a slightly 
 aromatic odour and a bitter sweet taste, freely colouring 
 the saliva. As they grow in dry and rocky formations 
 their wood is generally crooked and knotty. 
 
 Although these woods have long been employed as dye- 
 stuffs in the countries where they are grown, it is only since 
 the introduction of Brazil wood by the Spaniards that their 
 value has been fully appreciated in Europe. 
 
 Brazil ivood, derived from the Ccesalpinia Brasiliensis, 
 grows in the forests of Brazil, and may be considered as 
 the best of this class. It has become somewhat scarce in 
 the market from its having been all cut in those districts 
 which are within easy distance of shipping ports. 
 
 The wood most in favour at the present day is the pro- 
 duct of the CcBsalpinia Crista, and is imported from 
 Parahiba, Pernambuco, and Jamaica, and is known as Fer- 
 nambuco or Pernambuco wood. 
 
 Peachzvood, sometimes also called Santa-Martha wood, 
 
122 DYEING AND CALICO PRINTING. 
 
 derived from the Ccusalpinia cchinata, is imported from 
 Nicaragua, and an inferior quality from Sierra Nevada. 
 
 Sapan wood, the product of the Cczsalpinia sappan, is 
 imported from Siam, Japan, the East Indies, and other 
 Eastern countries. 
 
 Lima zuood, an inferior variety, is imported from Peru. 
 Other woods of the genus Ccesalpinia, known in commerce 
 as California wood, Bahia wood, Jamaica wood, and Sierra 
 Firma wood, are also imported to this country from 
 various parts of South America. 
 
 All these woods give very similar shades of colour on 
 fabrics, either when employed alone or with mordants; so 
 that it would appear that they contain the same glucoside, 
 which is decomposed by peculiar ferments into a saccha- 
 rine matter and a colour-giving principle. That this infer- 
 ence is correct is proved by the following experiments: — 
 If the decoction obtained by treating the wood from the 
 interior of the logs be boiled with a solution of double 
 tartrate of potash and copper (the best known test for 
 grape sugar), no precipitate is obtained; whilst if it be 
 first boiled with dilute sulphuric or hydrochloric acid 
 (which would decompose a glucoside), and afterwards 
 treated with the copper salt, an abundant precipitate of 
 the suboxide of that metal is thrown down. Although 
 the original solution, which has only a faint yellow colour, 
 gives no precipitate with acetate of lead, yet after it has 
 been boiled with acid it gives an abundant precipitate of a 
 brilliant brick-red colour. If a concentrated solution is 
 neutralised, after having been boiled with an acid to 
 decompose the glucoside, it deposits on cooling a small 
 quantity of the colouring principle in beautiful reddish 
 crystals. No such crystals can be obtained from the 
 original solution. 
 
 The colour-giving principle which appears to be the 
 same in all these woods was first obtained from Brazil 
 
BRAZILIN. 123 
 
 wood, by Chevreul, who gave it the name of brazilin. It 
 forms needles which are nearly colourless, and which have 
 a bitter sweet taste. 
 
 In 1865, Messrs. Mliller & Co., of Basle, placed in the 
 hands of Professor Bolley, some very large crystals which 
 had been deposited at the bottom of casks, in which an 
 extract of sapan wood had been kept for a considerable 
 time. These proved to be brazilin soiled by a little bra- 
 zilein. By crystallisation from alcohol he succeeded in 
 obtaining pure brazilin in the form of oblique rhomboidal 
 prisms, having a diameter of about one-tenth of an inch. 
 These are freely soluble in alcohol and ether, and on 
 analysis were found to have the formula C 22 H 20 O 7 + 30H 2 . 
 At a temperature somewhat below 212 F. it loses the 
 three molecules of water. 
 
 According to E. Kopp,* however, the formula of anhy- 
 drous brazilin is C. 22 H 18 7 , and its relation to hematoxylin 
 may be expressed in the following manner : 
 
 C 22 R } p 7 + OH 2 = C 16 H 14 6 + CcH.O,. 
 
 Brazilin. Water. Hematoxylin. Resorcin. 
 
 He finds that the crust, which is obtained in considerable 
 quantity in the manufacture of Brazil wood extract, con- 
 tains much brazilin, and brazilin lime lake. On treating it 
 with dilute hydrochloric acid to remove the lime, and then 
 boiling it with a mixture of one part of alcohol and eight 
 of water, a solution is obtained from which brazilin crystal- 
 lises out on cooling. It is well known that extract of sapan 
 wood when treated with nitric acid yields styphnic acid, 
 which is identical with the trinitroresorcin, produced by 
 the action of nitric acid on resorcin. Moreover, Schreder,-f- 
 by fusing extract of sapan wood with potassium hydrate, 
 has obtained resorcin; at the same time pyrOcatechin is 
 produced, and also a cystallisable substance, sappauin, to 
 
 * Deut. Chem. Ges., Ber. vi. 446. 
 + Deut. Chem. Ges., Ber. v. 572. 
 
124 DYEIXG AXD CALICO PRIXTIXG. 
 
 which he assigns the formula C.H : 4> 20H : . It dissolves 
 in boiling water, and crystallises out again on cooling. It 
 possesses no marked characteristics. 
 
 A solution of brazilin when exposed to the atmosphere 
 acquires a brilliant red colour, and is slowly oxidised to bra- 
 zilein ; this action may be much accelerated by heating the 
 liquid, especially in the presence of alkalis. On allowing 
 the solution to evaporate, beautiful red needles are 
 deposited, having a satiny lustre. 
 
 The change, which is analagous to that which takes 
 place with haematoxylin, may perhaps be represented by 
 the following equation: 
 
 C..H :: 7 - O = C.H. O, - OH 2 . 
 
 Brazilin. Brazilein. 
 
 Brazilein dissolves freely in water, alcohol, and ether. It 
 is easily reduced to the colourless brazilin by boiling its 
 solution with bisulphite of soda. 
 
 According to Reun, a crystalline brazilein may be ob- 
 tained from brazilin, in a manner precisely similar to that 
 described when treating of the conversion of haematoxylin J & 
 into haematein. 
 
 On adding chromic acid or bichromate of potash to a 
 concentrated solution of brazilin the liquid assumes a dark 
 brown colour, and in a little while a very dark crimson lake 
 separates, which is a compound of brazilein with oxide of 
 chromium. This compound is not very stable, as it is 
 easily decomposed by dilute hydrochloric acid. This reac- 
 tion illustrates the use made of bichromate of potash by 
 the calico printer when dyeing with these woods. 
 
 A decoction of any of these woods becomes yellow or 
 orange (according to the quantity of brazilin or brazilein it 
 contains) on the addition of an acid; by the aid of heat 
 the conversion of the brazilin into brazilein is hastened, 
 and it is the latter compound the dyer and printer require. 
 The transformation is still more rapidly effected by the 
 
REACTIONS OF BRAZIL WOOD. 125 
 
 addition of a small quantity of potassium bichromate or 
 chlorate. Great care, however, is required in using these 
 salts, for if too much be added a brown, resinous, nearly- 
 insoluble product is formed, which injures the brilliancy of 
 the colour; this may occur also in the preparation of the 
 extract if the operation is not carefully conducted. The 
 addition of an alkali to a decoction of the wood produces 
 a magnificent crimson-red, varying in shade according to 
 the proportion of the two principles present. 
 
 The following reactions will serve to characterise decoc- 
 tions of these woods : — Acids turn them yellow, of a more 
 or less orange shade, the shade varying with the variety 
 and state of oxidation of the wood from which the decoc- 
 tion is prepared ; after a certain time crystals are separated, 
 which are yellow if the decoction is not much oxidised, 
 but red if the contrary be the case. It seems probable 
 that these crystals are deposited on account of the splitting 
 up of the glucoside into sugar and the colouring matter, and 
 the latter, being comparatively slightly soluble, separates 
 in the crystalline state. An excess of strong hydrochloric 
 acid alters the shade to a bright pink, but it disappears on 
 the addition of water. The alkalis, caustic or carbonated, 
 give a crimson-red tint. Chromate of potash, as already 
 mentioned, gives a dark red liquor, which on standing 
 deposits a deep red precipitate. Neutral acetate of lead 
 only gives a slight reddish precipitate. The filtered liquor, 
 although almost colourless itself, dyes with a deeper shade 
 than the original liquor. It appears, therefore, that acetate 
 of lead merely precipitates the superoxidised matters and 
 the substances which injure the beauty of the colour. Sub- 
 acetate of lead gives an abundant bluish precipitate. These 
 tests are sufficient to characterise the Brazil wood colours. 
 
 To prepare a good commercial extract from the woods 
 they must be finely ground, as they yield their colour to 
 water with difficulty; like logwood, they should be allowed 
 
126 DYEING AND CALICO PRINTING. 
 
 to ferment and partially oxidise in the air before being 
 treated with water, but not to the same extent; the more 
 quickly the solutions are evaporated the brighter is the 
 colour produced. From a ton of sapan wood there is 
 usually obtained about 640 gallons of liquor, marking about 
 2^ Twaddle, and this is evaporated to 150 gallons, marking 
 7 to 7 l /> Twaddle. The apparatus employed consists of a 
 double copper vessel or trough, the space between being 
 supplied with steam ; in this revolves also a copper steam 
 cylinder. By this arrangement a very large amount of 
 heat is imparted to the liquid placed in the trough, and 
 the steam given off in the evaporation prevents the over 
 oxidation of the extract. With a machine, having a cylin- 
 der 4 feet 8 inches long by 2 feet 6 inches in diameter 
 making twelve revolutions per minute, with steam at 
 a pressure of 30 lbs., 640 gallons can be evaporated to 
 150 in ten hours. If the finely rasped wood be exposed 
 to strong sunlight for twelve months it no longer yields 
 any colouring matter. 
 
 Dingler's process for the preparation of an extract from 
 these woods is said to give very good results. It consists 
 in adding 4 lbs. of gelatin dissolved in water to every 
 cubic yard of ground wood, and allowing the whole to 
 ferment for several days. Wood so treated yields a 
 stronger and richer extract than that obtained by the 
 ordinary process ; it is possible that the gelatin assists the 
 decomposition of the glucoside, and that the ammonia pro- 
 duced by the putrefaction of the animal substance facili- 
 tates the oxidation of the brazilin. Mr. Peak, some years 
 ago, found that the addition of a small quantity of chlo- 
 rate of potash to the hot extract greatly increased its 
 brilliancy and rendered it more valuable to the printer on 
 account of the brighter colour produced on the fibre. 
 
 These extracts give with iron and alumina mordants 
 colours similar to those obtained with madder, namely, 
 
DYEING WITH BRAZIL WOOD. 
 
 127 
 
 purple with salts of iron, red with salts of alumina, and 
 chocolate with a mixture of the two, but they are princi- 
 pally used to obtain pinks and reds in steam styles. To 
 effect this acetate of alumina, chloride of tin, oxalic acid, 
 or acetate of copper is added to the extract and printed 
 on prepared cloth, as already described, which is then 
 submitted to the action of steam. The fastness of the 
 colours so produced is much increased by adding a little 
 sumach extract to the wood solution. M. K. Koechlin, 
 of Alsace, has been kind enough to supply the accompany- 
 ing sample, illustrating the effect obtained with Brazil 
 wood. 
 
 BRAZIL WOOD ROSE COLOUR. 
 
 The extracts are also used in conjunction with a little 
 quercitron or bark in the production of cheap garancin 
 styles. These inferior garancin prints are easily distinguished 
 from the good ones by means of a hot soap bath, which 
 only slightly affects the latter whilst the former are almost 
 entirely destroyed. The woods themselves also are some- 
 times used for the adulteration of garancin. 
 
 Before leaving this subject it may be stated that decoc- 
 tions of these woods yield very beautiful pink lakes, much 
 
128 DYEING AND CALICO PRINTING. 
 
 used by decorators and paper stainers under such names 
 as Venetian, Florence, or Berlin lakes. Most of them are 
 obtained by saturating a strong decoction of wood with 
 a mixture of chalk, starch, and a little alum, pressing the 
 whole into cakes and drying them. Venetian lake, the 
 best of the class, is prepared by mixing a decoction of 
 Brazil wood with gelatinous alumina and gelatin, and 
 brightening the tint by the addition of a little alum in 
 solution ; the mass is then dried. If it is wished to have a 
 purple lake a certain proportion of soap is added before 
 drying. Common red ink is also prepared by adding a 
 little alum and acid to a decoction of these woods. 
 
 Sandal, Bar, and Camwoods. — The dyestuffs of the 
 next class, which are almost insoluble in water, are derived 
 from several varieties of the genus Ptcrocaipns, which are 
 indigenous to the tropical parts of both the new and the 
 old world. 
 
 Sandal wood, called also Santal or Sanders zi'ood, the 
 produce of the Pterocarpus santalinus is much used in 
 India as a dyestufif. It is imported into this country from 
 the East Indies, Ceylon, Madagascar, and the coasts of 
 Coromandel and Malabar, and consists of. large billets 
 which have a compact and hard appearance, and a dull, 
 murky, red colour. It is more used on the continent than in 
 England, and yields to alcohol about 16 per cent, of 
 colouring matter, insoluble in water. 
 
 Barwood is the wood of a fine tall tree, called BapJiia 
 nitida, growing in great quantities at Sierra Leone. It 
 yields to alcohol about 23 per cent, of colouring matter, but 
 coid water extracts very little, and boiling water only about 
 7 per cent. Acetic acid and alkalis dissolve out the 
 colouring matter. 
 
 Camzi'ood, or Kambe wood, is a dyewood very closely 
 allied to the two just mentioned, and is also imported from 
 the west coast of Africa. Owing to its price being higher 
 
SANTALIN. 
 
 129 
 
 than that of barwood it is not extensively used, and its 
 general properties and the character of its colouring matter, 
 have not been much studied. 
 
 The colouring principles which these three dyewoods 
 contain appear to be very similar, if not identical. It is 
 only developed by age, not being found in the young 
 branches, whilst it exists in large quantities in the trunk. 
 Pelletier first isolated the colouring matter from sandal 
 wood under the form of a red resin. Preisser stated 
 that he had obtained it as a white crystalline mass, by 
 mixing hydrated oxide of lead with an ethereal solution of 
 the wood, and after well washing the lake thus formed, 
 decomposing it by sulphuretted hydrogen; the product was 
 then heated with ether, and the ethereal solution evaporated 
 in vacuo. According to Meier, sandal wood contains four 
 substances soluble in water, and two which are insoluble, 
 namely, santalic acid and santalin. He prepares the latter 
 by exhausting the wood with ether, and evaporating the 
 ethereal solution, when it leaves the impure santalin in a 
 crystalline state. After washing it with water it is dissolved 
 in alcohol and precipitated with lead acetate. The lead 
 compound is then thoroughly washed with boiling alcohol, 
 and decomposed by dilute sulphuric acid. Thus obtained 
 it forms small bright red crystals, having the formula 
 C 15 H u 5 .(?) 
 
 The colouring matter of sandal wood is insoluble in cold 
 water, very slightly soluble in hot water, but soluble in 
 alcohol, ether, and acetic acid. The latter solvent yields 
 the colouring matter to albumen, which is an important 
 fact, and may one day be rendered practically useful. 
 Santalin is freely soluble in alkaline solutions, giving a 
 violet-red liquid, from which acids precipitate the colouring 
 matter in red flakes. Bolley considers that the wood con- 
 tains two principles, one containing more oxygen than the 
 other, and two equivalents more hydrogen. 
 K 
 
130 DYEING AND CALICO PRINTING. 
 
 Weidel,* who has recently studied the nature of the 
 colouring matters of sandal wood, has succeeded in isolating 
 two crystalline substances ; one of these, santal, is colour- 
 less, and is perhaps identical with the santalin of Preisser ; 
 the other, santalin, is a bright red compound, and is 
 probably the santalin of Meier, Westermann, and Haeffely. 
 
 Santal is obtained by treating the wood with a weak 
 alkaline solution, and then neutralising the extract with 
 hydrochloric acid, which throws down a precipitate. This, 
 after being collected, washed, and dried, is exhausted with 
 ether. The ethereal solutions are then mixed with alcohol 
 and the whole allowed to evaporate spontaneously. In the 
 course of a few days nearly colourless crystals of santal 
 are deposited, which only require to be washed with a little 
 alcohol to be quite pure. 
 
 Santal crystallises from hot alcohol in colourless, lustrous 
 plates, having the formula 2C 8 H O 3 + 3OH0. They are 
 tasteless, inodorous, insoluble in water, bisulphide" of car- 
 bon, benzene, and chloroform, and only slightly soluble in 
 alcohol and ether. Its alkaline solution has a yellow 
 colour, which becomes rapidly red in contact with the air, 
 and gives a red precipitate with salts of lime and baryta. 
 Its alcoholic solution assumes a dark red colour with per- 
 chloride of iron. When fused with caustic potash it yields 
 protocatechuic acid according to the following equation : — 
 C 8 H G 3 + 3 = C 7 H c 4 + COo. 
 
 Santalin. Protocate- 
 
 chuic acid. 
 
 A thousand parts of wood yield three parts of santal. 
 
 If the wood which has been acted on by alkalis is 
 treated with ether and the solution evaporated, it deposits 
 a red substance, which as the ether evaporates assumes a 
 crystalline form. It has a magnificent scarlet colour, with 
 a green metallic iridescence, and is the santalin of Weidel. 
 
 Zeits. Chem. [2] vi., 83. 
 
BAR WO OD. 131 
 
 He assigns to it the formula C 14 H 12 4 , which only differs 
 from alizarin by four equivalents of hydrogen. It is in- 
 soluble in water, only slightly soluble in alcohol and ether, 
 and imparts a reddish-purple colour to alkalis. 
 
 It will be seen from this short description that, at 
 present, our knowledge of the colouring matters contained 
 in these woods is very imperfect. 
 
 Sandal wood is employed, chiefly on the continent, to 
 give a bottom* to woollen cloth which is to be afterwards 
 dyed with indigo. By this process a very fine blue is pro- 
 duced, called the bleu de Nemours, having a purple hue 
 by reflected light. It is also used to impart to woollen and 
 cotton goods a dark red colour, which is changed to a rich 
 brown when passed through a bath of bichromate of 
 potash. With sumach it produces dark browns, and with 
 fustic light browns. 
 
 Banvood, which was imported into Europe by the Portu- 
 guese, is now extensively used in England for producing on 
 cotton yarns the brilliant orange-red colours known as 
 mock Turkey reds. They are, however, neither so fast nor 
 so bright as the real Turkey red, and are easily dis- 
 tinguished from it by yielding part of their colour to soap, 
 assuming at the same time a purple hue. To obtain the 
 colours the goods are worked for some time in a hot decoc- 
 tion of sumach, then in a solution of protochloride of tin, 
 out of which it is washed first in cold and then in hot 
 water ; after this it is put in a bath with the ground wood 
 and kept for some time at a boiling heat until the desired 
 depth of colour is obtained. It is also often used along 
 with other woods in dyeing woollens brown and other dark 
 mixed tints. 
 
 *This term is used in dyeing to denote that a colour is applied to a fabric 
 with a view of giving a peculiar hue to a dye which is applied after it. 
 
132 
 
 DYEING AND CALICO PRINTING. 
 
 MOCK TURKEY RED.* 
 
 Camwood is used in a similar manner to barwood, and 
 the colour is considered by many to be both brighter and 
 faster than that of the latter. 
 
 The following reactions may serve to characterise an 
 alcoholic solution of sandal and barwoods: — 
 
 Produces a considerable yellow 
 
 Distilled water, added in 
 large quantity, 
 
 Chlorine. 
 
 Gelatin 
 
 Soluble alkalis. 
 
 Lime water. 
 
 opalescence. The precipi- 
 tate is redissolved by the 
 fixed alkalis, the liquor ac- 
 quiring a dark vinous hue. 
 
 Decolourisation, with brown- 
 ish-yellow floculent precipi- 
 tate, resembling hydrated 
 peroxide of iron, which soon 
 rises to the top of the liquid. 
 
 Brownish-yellow floculent pre- 
 cipitate. 
 
 It becomes dark crimson or 
 violet. 
 
 Abundant reddish-brown pre- 
 cipitate. 
 
 * We are indebted for this sample to the kindness of Messrs. Wood & Wright. 
 
SORGHO. 
 
 133 
 
 Sulphuric acid. 
 
 Sulphuretted hydrogen. 
 Protochloride of tin. 
 Bichloride of tin. 
 
 Protosalts of iron. 
 
 Persalts of iron. 
 Persalts of copper. 
 
 Salts of alumina. 
 
 Salts of lead. 
 
 Mercuric chloride. 
 Nitrate of silver. 
 
 Sulphate of zinc. 
 Tartar emetic. 
 Salts of bismuth. 
 
 Heightens the colour to a 
 
 cochineal-red. 
 Acts like water. 
 Blood-red precipitate. 
 Brick-red precipitate. 
 Violet colouration and abun- 
 dant violet precipitate. 
 Intense brownish-red coloura- 
 tion and precipitate. 
 Merely render the liquid tur- 
 bid. 
 Dark violet gelatinous pre- 
 cipitate. 
 Bright red precipitate. 
 Brownish-red precipitate. 
 J Bright red floculent precipi- 
 l tate. 
 Abundant dark cherry-colour- 
 ed precipitate. 
 Solution coloured bright crim- 
 son-red. 
 
 Camwood differs from the above in the two following- 
 reactions : — 
 
 Salts of lead. Bright orange-red precipitate. 
 
 Salts of alumina. Beautiful red colouration. 
 
 There are two other dyewoods closely allied to the 
 above — one called Caliatour wood, imported from the East 
 Indies, which gives even more brilliant colours than sandal 
 wood; the other is from Madagascar, but comes only in 
 very small quantities. 
 
 SORGHO. — Sorgho, the Sorghum saccharatum, is the 
 Chinese sugar cane, a plant somewhat resembling maize 
 in appearance. It was first grown from seed in France in 
 1853, and has since been cultivated in France and Germany 
 for the quantity of sugar which it yields. If the pith of 
 
134 DYEJXG AND CALICO PRINTING. 
 
 this plant is subjected to pressure, it yields a juice which, 
 when either allowed to ferment, or boiled with dilute 
 sulphuric acid, gives a colouring matter which has received 
 the name of pnrpnrolcin, sorgho carmine, or sorgho red. 
 MM. Sicard, Itier, and Joulie state that the external part 
 of the fruit of the sorgho gives two other colouring matters, 
 sorghotin and sorghin. 
 
 Dr. Winter obtained a colouring matter which may be 
 employed as a dyestuff, by allowing the stems of the plant 
 to ferment until they acquire a reddish-brown colour; when 
 dry they are cut into small pieces and treated with a dilute 
 alkaline solution, from which a red fioculent precipitate is 
 produced on the addition of sulphuric acid. By means of 
 a tin mordant this colouring principle may be fixed on 
 wool and silk. 
 
 The Chinese employ the colouring matter produced by 
 fermentation, as a dyestuff to produce colours resembling 
 Turkey red in appearance. The bark of the sorgho con- 
 tains a yellow colouring matter which has received the 
 name of xantJiolein. 
 
 ALKANET. — Alkanet, the cortical parts of the Anchusa 
 tinctoria, is principally imported from the Levant and from 
 South Germany, and contains a colouring principle called 
 by Pelletier, who first isolated it, anchnsic acid. Bolley and 
 Wydler who some years since examined this root, extracted 
 the colouring matter as a beautiful red resinous mass, and 
 assigned to it the somewhat doubtful formula C^H^Og. 
 To prepare it the root is first heated with water to remove 
 all the matters soluble in that liquid, it is then dried and 
 exhausted with alcohol. This solution, which has a violet 
 colour, after being slightly acidulated with hydrochloric 
 acid, is evaporated to dryness, and the residue treated with 
 ether. The ethereal solution on evaporation leaves the 
 colouring matter anchnsin, or anchnsic acid, as a dark red 
 resinous mass. 
 
^ NO LIN 135 
 
 Anchusin is insoluble in water, soluble in alcohol, and 
 very soluble in ether, bisulphide of carbon, turpentine, and 
 the fixed oils. 
 
 Alkanet was formerly employed to produce on fabrics 
 various shades of violet, lilac, and lavender, but, on account 
 of its instability when exposed to light, it is now seldom 
 used. Its chief uses are in pharmacy to colour medicines, 
 in perfumery to colour oils and pomades, and in domestic 
 life to give a tint to the lime-wash used for the walls of 
 cottage rooms. 
 
 The colouring principle dissolved in alcohol gives a blue 
 colour with alkalis, a purple precipitate with bichloride of 
 tin, a crimson precipitate with protochloride of tin, and a 
 bluish-violet precipitate with acetate of alumina. 
 
 ^Enolin, or The Red Colouring Principle of Wines. 
 M. Glenard has separated the colouring principle of red 
 wines by the following process: — Subacetate of lead is 
 added to the wine, which produces a blue precipitate: this 
 is collected, well washed, and dried at 21 2° R, and is then 
 treated in a displacement apparatus, first with anhydrous 
 ether saturated with hydrochloric acid gas, and after- 
 wards by ether alone. The solutions thus obtained are 
 evaporated to dryness, and the residue treated with alcohol, 
 which on concentration and the addition of water yields a 
 red floculent precipitate. 
 
 The senolin thus prepared is insoluble in ether and ben- 
 zene, only slightly soluble in water, but dissolves freely in 
 alcohol. Its solution in this latter menstruum becomes 
 brown on being boiled for some time in contact with air. 
 The formula assigned to aenolin is C 10 H 10 O 5 . 
 
 It is also stated that a blue colouring matter exists in 
 wines, which is soluble in acetic and butyric acids, and 
 becomes green on contact with alkalis. Some chemists 
 consider it to be identical with the cyanin of flowers. 
 
 Safflower. — Although this dyestuff has lost much of 
 
136 DYEING AND CALICO PRINTING . 
 
 its value since the discovery of the aniline colours, it is 
 still extensively used in Lancashire for the production of 
 peculiar shades of pink for the Eastern markets. It is also 
 used for dyeing red tape, and there is no more striking 
 instance of 'red-tapism' than the love which is shown for 
 this particular colour by the users of that article. Much 
 cheaper pinks can be produced from aniline, but notwith- 
 standing attempts have many times been made to intro- 
 duce them, they have failed in every instance, because the 
 exact shade has not been attained. 
 
 Safiiower is the bloom of a peculiar thistle called the 
 Carthantus tiuctorius, which is indigenous to Egypt and the 
 Levant, but which is now cultivated in France, Spain, 
 Germany, Italy, Hungary, the Southern Asiatic territories 
 of Russia, the East Indies, and South America. 
 
 In France and Spain the small flowers composing the 
 heads of the thistle are picked off while in full bloom, and 
 dried in the shade; whilst in Egypt and India the plants 
 are watered morning and evening for several days pre- 
 viously to the bloom being collected, after which the bloom 
 is squeezed, washed with cold water to remove useless 
 matters, slightly pressed into lumps, and dried in the 
 shade ; this kind has about double the value of those from 
 other countries. 
 
 The safflower so prepared contains only from three to 
 six parts per thousand of the colour-giving principle, which 
 is called cartliamic acid or cartJiamiu. There are also two 
 yellow colouring matters present — one soluble in water, the 
 other insoluble in that menstruum. 
 
 M. Salvetat has published the following figures as giving 
 the composition of safflower: — 
 
 Yellow colouring matter, soluble in water 26 - i to 36 'o 
 
 Carthamin '3 to -6 
 
 Extractive matter 3 '6 to 6-5 
 
 Albumen 1 '5 to 80 
 
CAR THAMIC A CID. i 37 
 
 Wax -6 to 1*5 
 
 Cellulose 38-4 to 56*0 
 
 Silica ro to 8-4 
 
 Alumina and oxide of iron '4 to 1 "6 
 
 Oxide of manganese "i to "5 
 
 Besides these there is always a certain proportion of 
 pectic acid. 
 
 To prepare carthamic acid, safflower is introduced into 
 bags and washed with cold water until all the soluble 
 yellow colouring matter which it contains has been re- 
 moved, after which it is macerated for two hours in water,. 
 in which has been dissolved fifteen parts of crystallised 
 carbonate of soda for every hundred parts of safflower 
 taken. The liquor is then run off ; cotton yarn is dipped 
 into it, and lime juice, lemon juice, or citric acid added 
 to liberate the carthamin from its combination with the 
 soda, when it fixes itself in the fibre of the yarn. Up to 
 this point, the process is the same as that adopted in dye- 
 ing fabrics, but to obtain carthamin, it is necessary to treat 
 the washed cotton a second time with a weak solution of 
 carbonate of soda, which leaves the second yellow colouring 
 matter fixed on the cloth. The solution thus obtained is 
 acidulated with tartaric acid, when the carthamin falls as a 
 brilliant red, amorphous powder. It may be further purified 
 by solution in alcohol, and precipitation from that men- 
 struum by the addition of water. The safflower extract of 
 commerce is prepared by this method, except that the last 
 precipitation from alcohol is omitted, the red powder being 
 merely mixed with a little water. The red powder when 
 dried and mixed with a little French chalk is employed as 
 rouge. 
 
 The formula of carthamin, according to Schlieper* is 
 C u H 10 O 7 . A solution of this compound when dried on a 
 polished white surface leaves a varnish having a beautiful 
 
 *Ann. Chem. Pharm., lviii., 362. 
 
1 3 8 DYEING AND CALICO PRINTING. 
 
 red colour by transmitted light, whilst it assumes the 
 iridescence of cantharides by reflected light. It is in- 
 soluble in water and ether, but soluble in alcohol. On the 
 addition of sulphuric, nitric, or hydrochloric acid, this solu- 
 tion becomes yellow. Alkalis also turn it yellow or orange, 
 and the colouring matter rapidly undergoes alteration 
 when exposed to the air, or when boiled with water or 
 alcohol. It is owing to the fugitive nature of the colour 
 and its easy modification by acid or ammoniacal vapours, 
 that the delicate pinks produced from safflower have been 
 so successfully replaced by the pink aniline dyes. 
 
 To obtain the soluble yellow colouring matter already 
 referred to, the aqueous extract of safflower is rendered 
 slightly acid by means of acetic acid, and acetate of lead 
 added. The precipitate thus produced is removed by filtra- 
 tion, and to the clear liquid, ammonia is added in slight 
 excess, which throws down a yellow precipitate. This is 
 collected on a filter, washed, and then decomposed by dilute 
 sulphuric acid. The sulphate of lead so formed is separated, 
 and the aqueous solution evaporated, out of contact with 
 the air. Schlieper assigns the formula C 16 H 20 O 10 to the 
 yellow colouring matter thus obtained. It becomes brown 
 on exposure to the air. The colouring matter insoluble in 
 water has not been studied. 
 
 There is a particular extract extensively used in dyeing, 
 the preparation of which is kept secret. Its value depends 
 on the fact that the carthamin is rendered soluble in water. 
 
 This extract, as well as safflower, is employed to dye 
 silk, cotton, and flax in various shades of pink and red. It 
 is used also to produce scarlet shades, in which case the 
 fabrics are first dyed with annatto, then washed, and finally 
 topped with carthamin. 
 
 If the safflower is gradually and successively treated first 
 with weak solutions of carbonate of soda, and afterwards 
 with stronger ones, it will be found, that, whilst the first 
 
DYEING WITH SAFFLOWER. 139 
 
 extract yields the brightest and purest tints, the others will 
 give shades which are progressively inferior. Dyers have 
 taken advantage of this by first dyeing the goods with the 
 coarsest colours from the last extracts, and then topping or 
 blooming them with the bright colour yielded by the first 
 extract. 
 
CHAPTER V. 
 
 INDIGO. 
 
 This most valuable dyestuff was used in India and 
 Egypt long before the Christian era ; the Romans also were 
 acquainted with it, although they only used it as a pig- 
 ment, not knowing how to render it soluble and thereby 
 to avail themselves of it for dyeing. It is only since the 
 sixteenth century, or from the time of the discovery of the 
 passage to India round the Cape of Good Hope, that it 
 has become generally known in Europe; and even then its 
 employment as a dye was greatly retarded by the oppo- 
 sition it met with from the large vested interests of the 
 woad cultivators, who induced the English, French, and 
 German governments to promulgate several enactments 
 against its use. An idea of the severity of some of them 
 may be formed from the fact that Henry IV. of France 
 issued an edict condemning to death anyone who used 
 that pernicious drug called the 'devil's food.' It is only 
 since the year 1737 that the French dyers have had the 
 right to use indigo without restriction. 
 
 The plants which furnish indigo do not all belong to the 
 same family, but the most important are leguminous and 
 of the genus Indigofera. The most valued and most 
 largely cultivated species are the Indigofera tinctoria, 
 Indigofera dispcrma, Indigofera anil, and Indigofera 
 argentca. Among those less cultivated may be mentioned 
 the Indigofera pscudotinctoria, hirsuta, sericea, cytisoides, 
 angustifolia, trifoliata, glabra, glanca, &c. These plants 
 appear to be indigenous to the kingdom of Cambay or 
 
INDIGO MANUFACTURE. 141 
 
 Guzerat, but are also cultivated in India, China, Java, and 
 
 the East. It was also introduced into the West Indies 
 
 and South America by the Spaniards. The Indigofcra 
 
 argentea is chiefly cultivated in Egypt and Arabia. The 
 
 indigofera tinctoria, Fig. 5, is the species 
 
 most abundantly grown, and is raised 
 
 from seed which is sown in spring or 
 
 autumn, according to the variety, the 
 
 nature of the soil, and the facility of 
 
 water supply. It is an herbaceous plant, 
 
 with a single stalk, growing to a height 
 
 of three feet or three feet six inches, and 
 
 about the thickness of a finger. It is 
 
 generally cut for the first time in June or 
 
 July, just before the plant is in full Fig. 5. 
 
 bloom, a second and third cutting being obtained during 
 
 the year. When cut it is made into bundles and taken to 
 
 the factory. The value of the crop is almost in proportion 
 
 to the abundance of leaves the plant bears, as the colouring 
 
 matter exists chiefly in that part of the plant. 
 
 The Bengal factories usually contain two rows of vats, 
 the bottom of one row being level with the top of the 
 other. Each series numbers from fifteen to twenty, and 
 each vat is about 7 yards square and 3 feet deep ; 
 they are built of brickwork lined with stone or cement. 
 About a hundred bundles of the cut indigo plants are 
 placed in each vat, in rows, and pressed down with heavy 
 pieces of wood; this is essential to the success of the 
 operation. Water is then run in so as to completely sub- 
 merge the plants, when a fermentation quickly ensues 
 which lasts from nine to fourteen hours according to the 
 temperature of the atmosphere. From time to time a 
 small quantity of the liquor is taken from the bottom of 
 the vat to see how the operation is proceeding. If the 
 liquor has a pale yellow hue the product obtained from it 
 
142 
 
 D YEING AND CALICO PRINTING. 
 
 will be far richer in quality but not so abundant as if it 
 had a golden-yellow appearance. The liquor is then run 
 off into the lower vats, into which men enter and agitate 
 it by means of bats or oars, or else mechanically by means 
 of a dash-wheel : each vat requiring seventeen or eighteen 
 workpeople, who are kept employed for three or four 
 hours. During the operation the yellow liquor assumes a 
 greenish hue, and the indigo separates in flakes. The 
 liquor is then allowed to stand for an hour, and the blue 
 pulpy indigo is run into a separate vessel, after which it is 
 pumped up into a pan and boiled, in order to prevent a 
 second fermentation, which would spoil the product by 
 giving rise to a brown matter. The whole is then left to ■. 
 stand for twenty hours, when it is again boiled for three or 
 four hours, after which it is run on to large niters, which 
 are placed over vats of stonework about 7 yards long, 
 2 yards wide, and 1 yard deep. The niters are made by 
 placing bamboo canes across the vats, covering these with 
 bass mats, and over all stretching strong canvas. The 
 greater part of the indigo remains under the form of a 
 dark blue, or nearly black paste, which is introduced into 
 small wooden frames having holes at the bottom and lined 
 with strong canvas. A piece of canvas is then placed on 
 the top of the frame, a perforated wooden cover, which fits 
 into the box, put over it, and the whole submitted to a 
 gradual pressure. When as much of the water as possible 
 has been squeezed out the covers are removed, and the 
 indigo allowed to dry slowly in large drying sheds from 
 which light is carefully excluded. When dry it is ready 
 for the market. Each vat yields from 36 to 50 lbs. of 
 indigo. The best qualities of indigo are usually manu- 
 factured by Europeans, who bestow more care on the 
 operations than the natives. Some manufacturers, in order 
 to facilitate the precipitation, add a little lime water to the 
 indigo when it has been oxidised in the vat by agitation. 
 
WOAD OR PASTEL. 143 
 
 J. Sayers, in Djocjocarta, Java, proposes to add ammonia 
 during the fermentation, whereby, he says, that he obtains 
 a purer product. 
 
 The other plants which yield indigo are more frequently 
 used directly in dyeing blue than for extracting indigo. 
 The most important are the woad plant, or /satis liuctoria, 
 once extensively cultivated both in England and on the 
 continent; the Polygonum tinctorium and the Herium 
 tinctorium; the Asclepias tingens (of the family Ascle- 
 piadae); Eupatorium tinctorium (Compositae) ; Galega 
 tinctoria (Leguminosae) ; and several species of orchids, 
 which, when cut, also become blue at the section on expo- 
 sure to the air. 
 
 Woad, or pastel, Fig. 6, is a biennial plant of the cru- 
 ciferous order. The leaves are gathered in June in the 
 second year, when the lower leaves are beginning to wither. 
 Others grow in their places and a second crop may be 
 gathered. These leaves are rapidly washed and dried, and 
 used directly for dyeing; or they are made into a paste 
 with water, in heaps of about a yard high, and the fer- 
 mented mass after fifteen days made into small balls and 
 dried. Sometimes the mass, treated a second time with 
 a little water, is submitted to another fermentation, during 
 which ammonia is developed; the preparation thus ob- 
 tained is called woad. The best comes from Provence, 
 Languedoc, and Normandy. It is also found in commerce 
 in bales. In Germany the woad of Thuringia is almost 
 exclusively used. Woad is frequently employed in dyeing, 
 mixed with ordinary indigo, as some manufacturers con- 
 sider that they cannot obtain the finest shades without it. 
 The balls are light, of a sickly odour, and of a green or 
 yellowish-green colour. If cut, it ought to have a soft 
 shining surface, and when rubbed on paper it should 
 leave a green mark. It gains in tinctorial power by 
 keeping. 
 
144 
 
 D YEING AND CALICO PRINTING. 
 
 Flower. Seed. Fig. 6. 
 
 The Isatis indigotica. — Tein-hoa-tein-ching is grown in 
 most of the provinces of China, for the preparation of a 
 kind of indigo, which is sold as a viscid paste. When dried 
 it has a blackish colour, and is used for the production of 
 Canton blue, &c. 
 
 The Polygonum tinctorium, Fig. 7, is a herbaceous plant 
 of the family Polygonese, also indigenous to China, where a 
 greatly esteemed variety of indigo is prepared from its 
 leaves. It is also used for dyeing directly. Many attempts 
 have been made to acclimatise this plant in Europe, but 
 although they have grown well, the yield of indigo has 
 been too small to make it worth the trouble of cultivation. 
 This was clearly demonstrated by many French chemists 
 in the year 1839. 
 
VARIETIES OE INDIGO. 
 
 145 
 
 Flower. 
 
 Seed. 
 
 Fig. 7. 
 
 The indigo extracted from the various species of indi- 
 gofera varies very much, both in the quantity of pure 
 indigo it contains, and also in its dyeing power. This 
 variation is still further increased by differences of climate, 
 and by the care taken in its preparation. There are thus 
 many qualities known in the market, of which the best are 
 those of Java, Bengal, and Guatemala. 
 
 Twenty years ago we had no definite information as to 
 the state in which the colour-giving principle exists in 
 the indigofera plant, nor of the changes which it under- 
 goes during the process of extraction. It had been stated 
 by Chevreul, many years before, that the white indigo was 
 held in solution in the plants by the vegetable fluids, and that 
 on coming into contact with the oxygen of the atmosphere 
 it absorbed oxygen, and was converted into the insoluble 
 or blue indigo. In the year 1855, however, and subse- 
 L 
 
146 D YEING AND CALICO PRINTING. 
 
 quently in 1857 and 1865, Schunck published some most 
 interesting papers, in which he described the true nature of 
 the chemical changes which take place in the manufacture 
 of indigo, and proved that indigotin (the colouring matter 
 of indigo), like the colouring principles of madder and the 
 dyewoods, existed in the plant as a glucoside to which he 
 gave the name of indican. Schunck expresses the formula 
 of indican and the decomposition it undergoes as follows : 
 
 C 2G H 31 NO 17 +2OH 2 =*C 8 H 5 NO + 3C 6 H 10 O G . 
 
 Indican. Water. Indigotin. Indiglucin (Sugar). 
 
 In his researches on this substance Schunck operated on 
 the Isatis tinctoria or woad, which contains the same 
 colouring principle as the indigoferae, and is the only plant 
 yielding indigo which grows freely in this country. The 
 following was the process he adopted to prove that indican 
 existed in the plant, and was not a product formed either 
 by any chemical reaction, or by the reagents he employed.-f* 
 
 Dried woad leaves were treated with ether, and the 
 ethereal extract poured off into a large bottle and well 
 shaken with half its volume of cold water. The ether 
 was then separated, and the weak aqueous solution of the 
 colour-giving principle agitated with several successive 
 quantities of the ethereal extract, whereby it acquired a 
 yellow colour. The ether it contained was then removed 
 by spontaneous evaporation, and the solution evaporated 
 in a bell-jar over sulphuric acid. The residue consisted of 
 nearly colourless indican, which, when acted on by sulphuric 
 acid, yielded indigo blue. In 1857 he published the follow- 
 ing process:^ — Dried woad leaves, after being reduced to 
 powder and carefully sifted, were extracted with alcohol in 
 a displacement apparatus. To the solution thus obtained 
 a little water was added, and it was then concentrated as 
 quickly as possible at the ordinary temperature by passing 
 
 *This formula should be doubled, C 16 H 10 N„O«. — Eds. 
 + Lit. Phil. Soc. Man., 1855, xii., 192. 
 X Lit. Phil. Soc. Man., xiv., 184. 
 
PREPARATION OF INDICAN. 
 
 H7 
 
 a current of air rapidly over the surface of the fluid. This 
 was done in an ingenious apparatus which he devised for 
 the purpose, and which will be described further on. After 
 a few hours there remained a dark green residue, consisting 
 of fat and green colouring matter, with a light brown liquid 
 resting above it. This liquid was poured off, filtered, 
 agitated with a quantity of freshly precipitated oxide of 
 copper, and again filtered. The copper in solution was 
 precipitated by sulphuretted hydrogen, and the liquor, 
 which was of a light yellow colour, evaporated in the 
 apparatus before mentioned. The brown syrup thus ob- 
 tained, after being treated with cold alcohol to remove 
 some decomposed indican, was mixed with twice its volume 
 of ether: other impurities were thus separated, and when 
 clear the solution was evaporated as before. A clear brown 
 syrup was thus obtained, consisting of pure indican. 
 
 Pure indican can only be prepared by the rapid evapora- 
 tion of its solution at the ordinary temperature, for it is 
 decomposed both by heat and by long exposure to the 
 atmosphere, giving rise to new products. On this account 
 the following description of the apparatus employed for 
 that purpose by Dr. Schunck* may be inserted here. 
 k 
 
 ■■ ■ ■ • • ' — : 
 
 '.-.■.. „■"■ • ' 
 
 - ., ; ., J ]' 
 
 Fig. 8. 
 
 * Lit. Phil. Soc, Man., xiv., 182. 
 
148 DYEING AND CALICO PRINTING. 
 
 Fig. 9. 
 "The solution to be evaporated is poured into a dish or 
 "tray of block-tin, about 16 inches square, with per- 
 pendicular sides 2 inches deep, and capable, therefore, 
 "of containing when full nearly 2 gallons of liquid. 
 "The dish is placed on a shelf fixed at a convenient height 
 "in a wooden box, of which a,b,c,d, Fig. 9, represents the 
 "front. This box is closed at the two sides, but open at 
 "the front and back from the shelf upwards. It must be 
 "sufficiently wide to allow the dish to slide easily in and 
 "out, but from front to back it must be so deep as 
 "to leave a space of about half an inch between the 
 "front and the dish. At the distance of about 1% inch 
 "from the back of the box, there is fixed in a perpen- 
 dicular position a board f, the upper and side edges of 
 "which arc firmly attached to the top and sides of 
 "the box. The lower edge of this board is about on 
 "a level with the upper edge of the tin dish, and is ac- 
 curately fitted to a shelf g, which is suspended by means 
 "of two upright pieces of wood Ji,h, 2^ inches deep, 
 
PREPARATION OF INDICAN. 
 
 149 
 
 "resting on two ledges i,i, fixed to the sides of the box. 
 "The spaces between J1J1, and the side walls of the box 
 "must be sufficiently wide to allow the sides of the tin dish 
 "to move easily up and down in them. By means of sup- 
 ports 11,11, inserted between the tin dish e, and the shelf o, 
 "the former may be raised so as to bring the surface of the 
 "liquid contained in it close to the shelf g, which is thus 
 "made to hang down within the dish. When the apparatus 
 "is to be used, the spaces/,/, left between the edges of the 
 "dish and the ledges i,i, are closed as tightly as possible 
 "by means of flat plugs of wood, so as to cause the current 
 "of air passing through the apparatus to sweep over the 
 "whole surface of the liquid. The front of the box is 
 "closed by means of a frame j,k,l,m, covered with muslin 
 "and sliding up and down in grooves fixed to the sides, 
 "which in a great measure prevents the dust which is 
 "carried along by the current of air from being conveyed 
 "into the liquid. The apparatus is now placed so as to 
 "make the back fit as closely as possible to the wall q,r, 
 "Fig. 8, in which there is an opening s, communicating with 
 "a steam boiler flue, or the back of the box may be closed 
 "with a piece of wood having an opening communicating 
 "by means of a pipe with the flue. The section, Fig. 8, 
 "shows the direction taken by the air in passing over the 
 "surface of the liquid. As the liquid evaporates the dish 
 "is raised by means of additional supports, so as again to 
 "bring the surface of the former close to the shelf g, and 
 "thus confine the current within a narrow space. The 
 "current of air which I employed, and which was suf- 
 "ficiently rapid to cause a constant ripple on the surface of 
 "the liquid, was produced by the draught of a steam boiler 
 "flue, which carried away the products of combustion from 
 "several large fires. I think it probable, however, that the 
 "same effect might be produced by causing the whole of the 
 "air necessary for the supply of an ordinary stove or close 
 
150 DYEING AND CALICO PRINTING. 
 
 "fireplace to pass through the apparatus. By means of 
 "the current of air at my disposal I was enabled to evapo- 
 "rate in this apparatus about a pint of water in the course 
 "of twenty-four hours, at a temperature not exceeding 
 "50° F., the temperature of the water being kept by means 
 "of the rapid evaporation rather lower than that of the 
 "atmosphere. The evaporation of a gallon of spirits of 
 "wine by the same means occupied only a few hours." 
 
 Prepared as described above, indican is a transparent 
 light brown syrup, from which it is impossible to separate 
 the water which it still retains without decomposing it. 
 Its aqueous solution has a yellow colour, a bitter taste, and 
 a slightly acid reaction. When boiled with caustic alkali it 
 evolves ammonia. The alkaline earths and weak alkaline 
 solutions produce a bright yellow colour with the aqueous 
 solution. Its alcoholic solution gives a bright yellow pre- 
 cipitate with acetate of lead, which is increased by the 
 addition of ammonia; the aqueous solution does not give 
 this reaction. 
 
 Action of Acids on Indican. — The most important 
 and characteristic property of indican is that when treated 
 with acids it readily splits up into indigotin, indirubin, and 
 indiglncin. If, to an aqueous solution, oxalic or tartaric 
 acid is added, and the mixture allowed to stand, it yields a 
 dark blue or purple precipitate, which is a mixture of indi- 
 gotin and indirubin. The same decomposition takes place 
 rapidly when an aqueous solution of indican is boiled with 
 a small quantity of sulphuric, hydrochloric, or nitric acid ; 
 the liquid first becomes of a sky blue colour, then opal- 
 escent, and lastly purple, leaving as the liquid cools a purple 
 deposit of indigotin and indirubin. Both these bodies may 
 be obtained in the crystalline state by sublimation. 
 
 If, however, an aqueous solution of indican be boiled or 
 heated for some time in a water bath, it undergoes a 
 change; and if it is now heated with an acid, instead of 
 
ACTION OF ACIDS ON INDICAN. 151 
 
 yielding the two bodies above described it gives dark brown, 
 almost black, flocks, which when washed, may, by treatment 
 with alcohol, be separated into two bodies, one soluble in 
 that menstruum named indiretin, the other insoluble named 
 indihumin. 
 
 This modified indican is no longer soluble in ether, and 
 only slightly soluble in alcohol, so that on treating the 
 alcoholic solution with ether the unchanged indican 
 remains dissolved, whilst the modified compound is pre- 
 cipitated. This alteration appears to consist in the indi- 
 can combining with the elements of water under the 
 influence of heat. In the decomposition of the modified 
 indican by acids, indiglucin is formed as in the case of the 
 unmodified one. 
 
 Schunck also found leucin in the indiglucin solution. 
 This compound is formed when various animal substances 
 are treated with sulphuric acid, and it also occurs as a 
 product of the putrefaction of cheese. He assigns to indi- 
 retin the formula C ls H 17 NO 10 , and to indihumin C s H 8 NO-. 
 The formula of leucin is C G H 13 N0 2 , and of indigotin 
 C 16 H 10 N 2 O 2 . Although he has analysed indirubin he has 
 not assigned to it any formula. 
 
 Schunck has also described two bodies, indifuscin and 
 indifulvin, which he considers to be directly derived from 
 indican. As they are produced only in very small 
 quantities, and do not give well-defined compounds, 
 it is unnecessary to enter into a minute description of 
 them. 
 
 Indigotin, the chief product of the action of acids upon 
 indican, will not be described here, as its great importance 
 as a dyestuff will render it necessary to enter somewhat 
 into detail as to its properties and those of some of its 
 chief derivatives. 
 
 Indirubin, the substance obtained from indican along with 
 indigotin, is probably identical with the indigo red of Ber- 
 
152 DYEING AND CALICO PRINTING. 
 
 zelius, and is formed especially when the decomposition is 
 effected by oxalic or tartaric acid. It is separated from the 
 indigotin by washing with alcohol the fioculent blue pre- 
 cipitate produced in the decomposition ; this dissolves the 
 indirubin and leaves the indigotin. On concentrating the 
 alcoholic solution, the indirubin crystallises out in long red 
 needles, which are^sbluble in alkaline solutions, and which 
 are easily reduced when heated with caustic soda and some 
 deoxidising substance, such as protochloride of tin or 
 grape sugar. On exposing this latter solution to the air it 
 yields purple flakes, which on being collected, washed, 
 dried, and heated between two watch glasses, give a sub- 
 limate of beautiful purple needles. These dissolve easily 
 in boiling alcohol, from which they recrystallise on cooling 
 in forms similar to those obtained by sublimation. 
 
 Indirubin dissolves completely in cold concentrated sul- 
 phuric acid, forming a beautiful purple solution, which on 
 being heated does not blacken, but on the contrary becomes 
 paler and gives off a trace of sulphurous acid. The solution, 
 when diluted with water, yields a fine purple colour to 
 cotton, wool, and silk. It dissolves completely in nitric 
 acid, and the solution, which is at first purple and then red, 
 becomes yellow on boiling. On evaporating this acid solu- 
 tion to dryness, and treating the residue with water, a 
 small quantity of picric acid is dissolved out, leaving a 
 brown resinous substance. 
 
 On boiling indirubin with a mixture of sulphuric acid 
 and potassium bichromate it is not decomposed, whilst 
 indigotin is. If it is reduced by means of a mixture of 
 ferrous sulphate with an alkali or other reducing agent, 
 a piece of calico dipped into the solution and then exposed 
 to the atmosphere, becomes dyed of a purple colour and 
 not blue, as would be the case with indigotin. The colour 
 is not removed from fabrics either by acids or soap, and 
 there seems to be little doubt that it is this substance 
 
INDIGLUCIN. 153 
 
 which gives to well dyed indigo goods that peculiar purple 
 tint which they possess. 
 
 Indiretin is obtained under the form of a dark brown 
 shining resin, which is transparent only when in very thin 
 layers. When heated, it is decomposed, and gives off 
 strongly smelling fumes, whilst an oil distils over : no 
 crystalline body is formed however. Nitric acid converts it 
 into a mixture of a brown resinous substance, with a little 
 picric acid. It dissolves in ammonia with a brown colour, 
 and the solution gives brown precipitates with the chlorides 
 of barium and calcium. Its alcoholic solution yields with 
 lead acetate a brown precipitate soluble in acetic acid. 
 
 Indihumin appears to be the indigo brown of Berzelius. 
 It is a sepia brown powder, insoluble in water and alcohol, 
 but soluble in alkaline liquids, forming brown solutions, 
 from which it is reprecipitated by acids in brown flocks. 
 Nitric acid decomposes it easily, forming a yellow solution 
 which on evaporation leaves an orange residue insoluble in 
 water. 
 
 Indiglucin is prepared by adding to the acid liquor from 
 which the above compounds have been separated an ex- 
 cess of acetate of lead. The sulphate of lead thus pro- 
 duced is removed by filtration, and to the filtrate an excess 
 of ammonia is added, when the indiglucin is precipitated 
 in combination with oxide of lead as a bulky yellow pre- 
 cipitate. This is washed and decomposed by sulphuretted 
 hydrogen. The sulphide of lead is separated, and if the 
 indiglucin solution is not perfectly colourless the last 
 treatment may be repeated, or the solution may be shaken 
 up with animal charcoal. The colourless liquid thus ob- 
 tained is concentrated to the state of a syrup in the appa- 
 ratus already described. The syrup is then dissolved in 
 alcohol, and on the addition of twice its volume of ether, 
 the indiglucin is separated as a pale yellow syrup, having 
 a sweetish taste. Mixed with concentrated sulphuric acid 
 
154 DYEING AND CALICO PRINTING. 
 
 it yields a dark red liquid, which blackens when heated. 
 It is converted into oxalic acid by boiling nitric acid. 
 With cupric sulphate and caustic soda it gives a blue solu- 
 tion, which on boiling becomes yellow, and then gives a 
 deposit of suboxide of copper. By the aid of heat it 
 reduces nitrate of silver and chloride of gold. Acetate 
 and subacetate of lead give no precipitate in its aqueous 
 solution, but one is obtained on the addition of ammonia. 
 On being mixed with milk of lime and filtered, it yields a 
 strong alkaline liquor, which, when boiled becomes quite 
 thick, owing to the separation of a mass of bulky yellow 
 flocks. As the liquid cools, however, these flocks completely 
 redissolve, forming a clear yellow solution. This precipi- 
 tation and re-solution can be" repeated many times. 
 
 When an aqueous solution of indiglucin is mixed with 
 yeast and allowed to stand in a warm place, no gas is given 
 off, nor is there any sign of fermentation, but after a few days 
 the liquor is found to have a strongly acid reaction owing 
 to the formation of acetic acid. The two characters last 
 described show that indiglucin is not identical with glu- 
 cose, but is a peculiar saccharine matter. 
 
 Leucin, as before stated, remains in solution with the 
 indiglucin, when indican is decomposed by boiling with 
 acid. The production of this compound from indican is 
 an interesting fact, as the same substance had been dis- 
 covered long before by Proust, among the products of the 
 putrefaction of gluten and cheese in presence of water. 
 Braconnot had also observed it as a product of the decom- 
 position of gelatin and other animal matters, and Frerichs 
 and Staedeler had found it in animal tissues. Within the 
 last few years it has been prepared synthetically. 
 
 It crystallises from an alcoholic solution in small flat 
 tables, having a pearly lustre, which like the fatty acids are 
 not wetted by cold water. It dissolves readily, however, in 
 boiling water, but is only sparingly soluble in alcohol, and 
 
ACTION OF ALKALIS ON INDICAN 155 
 
 insoluble in ether. When heated it volatilises without 
 decomposition, producing a sublimate having the appear- 
 ance of carded cotton. It is soluble in nitric and hydro- 
 chloric acids. It gives no precipitate with acetate of lead, 
 neither is one formed on the addition of ammonia, in 
 which respect it differs from indiglucin. 
 
 Action of Alkalis on Indican. — When an aqueous 
 solution of indican is mixed with caustic soda, it becomes 
 of a dark yellow colour, and if it be allowed to stand for 
 several days and then boiled with sulphuric acid, it yields 
 dark flocks, which on being collected and washed are 
 found to contain indirubin, but no indigotin. The indican 
 thus modified by the action of caustic alkali has received 
 from Schunck the name of vidicanin ; it may be prepared 
 by the following method : A solution of indican is mixed 
 with baryta water and left to stand until a portion of it on 
 being boiled with an excess of hydrochloric acid, no longer 
 yields indigotin, but indirubin only. The liquid is then 
 treated with sulphuric acid to precipitate the baryta, and 
 carbonate of lead is added to remove the excess of sul- 
 phuric acid. The solution after being filtered is treated 
 with sulphuretted hydrogen and the precipitated sulphide 
 of lead separated. The liquid is now concentrated in 
 Schunck's apparatus, and the dark yellow syrup obtained 
 is treated with alcohol, which dissolves the greater portion. 
 To this solution twice its volume of ether is added to 
 separate any indiglucin that may be present, and the clear 
 liquid is allowed to evaporate spontaneously, when it 
 leaves a yellow transparent glutinous residue which has a 
 bitter taste, and cannot be distinguished in appearance 
 from indican. It is soluble in ether and alcohol. The 
 latter solution yields a bright sulphur-yellow precipitate 
 with acetate of lead, soluble in excess of the reagent when 
 heated, but which reappears on the addition of ammonia. 
 It is decomposed into indirubin and indiglucin, on being 
 
156 DYEING AND CALICO PRINTING. 
 
 boiled with dilute sulphuric acid. The aqueous solution of 
 indicanin, when boiled with caustic soda, assumes a dark 
 yellow colour, and gives off ammonia. From the following 
 equation it will be seen that indicanin is formed from 
 indican by the taking up of one molecule of water and the 
 loss of one molecule of indiglucin. 
 
 C 26 H 31 N0 17 + OH, = C 20 H 23 NO 12 + C c H 10 O G . 
 Indican. Water. Indicanin. Indiglucin, 
 
 It would seem, therefore, that the action of alkalis on 
 indican is very similar to that of a moderate heat, differing 
 only in the amount of water combined. 
 
 The action of alkalis alone on indican having been 
 briefly described, it will be advisable to consider what is 
 the effect produced when alcohol, or alcohol and a reducing 
 agent is present as described by Schunck in his last paper 
 on this subject.* He states that having almost constantly 
 employed the process of Fritzsche (to which we shall have 
 to refer hereafter) in preparing indigotin, he observed that 
 when he employed but a small quantity of indigo as com- 
 pared with the quantities of alcohol, grape sugar, and 
 caustic soda, he found that after the indigo had been 
 reduced by the application of heat, instead of reappearing 
 when the liquid was agitated in contact with air, as it does 
 when proper proportions are used, the fluid maintained its 
 yellow colour and no blue indigo appeared. This unforeseen 
 result led him to make a series of experiments, by which 
 he found that the action of caustic soda and grape sugar 
 on the alcohol produced acetic acid, which combined with 
 the alcohol and indigotin to form a compound which did 
 not yield its indigo on being agitated in contact with the 
 air. He found that he could obtain a similar result by 
 substituting acetate of soda for the grape sugar. By these 
 means a dark brown liquid was produced which was 
 mixed with sulphuric acid until it had a slightly acid re- 
 
 * Lit. Phil. Soc. Man., xiv., 181. 
 
OXINDICANIN. 1 5 y 
 
 action, and evaporated to dryness. The residue, after being 
 washed with water to remove the sulphuric acid and 
 sulphate of soda, was found to consist partly of resinous, 
 and partly of pulverulent substances. From this residue 
 Schunck has separated five distinct compounds, all of which 
 are amorphous, and none of them possess characteristic 
 properties; he has, however, ascribed formulas to them. 
 The substances have not been named, but the following are 
 the equations which show their modes of formation: 
 
 Indigo. Alcohol. Acetic Acid. Water. 
 
 A. C 8 H 3 NO +8(C S H 6 0)+ 3 (C 2 HA)= C 31 H 39 N0 4 + i 3 OH a 
 
 + co 2 . 
 
 B. C 8 H 5 NO + 3 (C 2 H 6 0) + 3 (QH 4 2 ) = C 20 H, 3 NO 4 + 60H 2 
 
 C. C 3 H 5 NO + C 2 H G + 2(C 2 H 4 2 )= C u H u N0 4 + 4 OH 2 
 
 D. 2(C 8 H 5 NO) + 2 (C 2 H 6 0)+ 4 (C 2 HA)= C 28 H 2i N 2 5 + 7 OH 2 
 
 E. 2 (C 8 H 5 NO)+ C 2 H G + 5(C,.H 4 2 ) = 2 (C U H 11 N0 3 ) + 7 OH 2 
 These results enabled Schunck to explain some special 
 
 chemical reactions which occasionally occur in the manu- 
 facture of indigo. If the indigo manufacturer does not 
 take the greatest care in conducting the process of fermen- 
 tation, he will either get an inferior quality of indigo, or a 
 great decrease in the yield of the product, and in some 
 cases even entirely lose the colouring matter. These results 
 take place when the fermentation is either too rapid or too 
 prolonged, the indican in these cases being decomposed into 
 indigotin and indiglucin as usual, but besides this the indi- 
 glucin also undergoes a further decomposition into alcohol 
 and acetic acid, which combine with the indigotin to form 
 the mixture of compounds before mentioned, which does 
 not yield its indigo on agitation in contact with the air. 
 
 Oxindkanin.— -When in the preparation of indican the 
 solution has been evaporated in Schunck's apparatus, and 
 is treated with alcohol to dissolve the indican, an insoluble 
 residue is left, to which he has given the name oxindicanin. 
 It is easily purified by solution in a small quantity of 
 
158 DYEING AND CALICO PRINTING. 
 
 water and precipitation by alcohol. It is a brown glu- 
 tinous substance, having the appearance of gum. When 
 heated it gives off strongly smelling fumes, and a trace of 
 a crystalline substance sublimes which has a nauseous, but 
 not a bitter taste. When its aqueous solution is mixed 
 with sulphuric acid and boiled, it slowly deposits brown 
 flakes, which have the properties of indifuscin, whilst the 
 liquor contains indiglucin. The formula he assigns to it is 
 C 20 H 23 NO 16 . 
 
 Having noticed indican and the various products ob- 
 tained from it, which are of scientific interest but of no 
 commercial value, we shall proceed to describe somewhat 
 fully the important colour-giving principle indigotin, 
 already mentioned as one of the products of the decom- 
 position of indican when submitted to the action of acids. 
 
 Pure indigotin may be prepared on a small scale by 
 taking two shallow platinum capsules of about 3 inches in 
 diameter, and of such a depth that when placed together 
 with their concave surfaces inwards, they are about y§ of 
 an inch apart in the centre. In the middle of the lower 
 capsule are placed about 10 grains of coarsely pulverised 
 indigo. On applying a heat of 300 or 400 F. the indi- 
 gotin sublimes in beautiful needles of a purple colour and 
 red metallic lustre, which when examined under a micro- 
 scope are seen to be right rhombic prisms. They have a 
 specific gravity of 1*35, and after being washed with ether 
 or hot alcohol are pure indigotin. These crystals, when 
 heated in the open air, volatilise entirely, giving off beauti- 
 ful violet vapours resembling those of iodine and having a 
 peculiar odour, but when distilled in a close vessel scarcely 
 any unaltered indigo sublimes, the chief products being 
 aniline, empyrcumatic oils, and carbonate and cyanide of 
 ammonium, whilst a bulky carbonaceous mass is left in the 
 retort. 
 
 Indigotin is insoluble in water, alcohol, ether, and weak 
 
IS ATTN. 159 
 
 acids and alkalis, but soluble in creosote, phenol, amylic 
 alcohol, chloroform, and bisulphide of carbon. Its best 
 solvents, however, are nitrobenzene and aniline. If finely- 
 powdered indigo be boiled with aniline it readily dissolves, 
 forming a blue solution, which if filtered hot, and set aside 
 to cool for some time, deposits almost the whole of the 
 indigo in the crystalline state. After being washed with 
 alcohol and dried, it is chemically pure, having a brilliant 
 coppery lustre, and rivalling in appearance that prepared 
 by sublimation. Boiling paraffin may also be employed 
 for this purpose, the solution having the fine red colour of 
 indigo vapour; in fact, a dilute solution can scarely be dis- 
 tinguished from an alcoholic solution of magenta. When 
 cold, the indigo crystals, which closely resemble those of 
 sublimed indigotin, may be purified by washing them with 
 benzene. Indigo can also be crystallised from Venice tur- 
 pentine, and from high boiling point petroleum. Anhy- 
 drous acetic acid, to which a drop or two of sulphuric acid 
 has been added, dissolves a sufficient quantity of indigotin 
 to give fast colours when printed on fabrics. If water is 
 added to the solution the indigotin is precipitated un- 
 altered. 
 
 Indigotin, under the action of oxidising agents, such as 
 nitric acid, yields three distinct products — isatin, indigotic 
 or nitrosalicylic acid, and picric acid. 
 
 Isatin C 8 H 5 N0 2 , was discovered independently by Erd- 
 mann and by Laurent in the year 1841. It may be 
 prepared as follows : 1 lb. of indigo is mixed with water so 
 as to produce a thin paste, which is then heated, and nitric 
 acid of specific gravity 1*35 gradually added until the blue 
 colour of the indigo has disappeared : this usually requires 
 8 to 12 ozs. The product is then diluted with a large 
 quantity of water, boiled, and filtered. On cooling, the 
 impure isatin separates from the filtrate as a brown deposit. 
 To remove a dark coloured semi-fluid resinous body which 
 
160 DYEING AND CALICO PRINTING. 
 
 adheres to the isatin, it is dissolved in a solution of caustic 
 soda and carefully neutralised with hydrochloric acid. By 
 this means the resin is first precipitated, and on filtering 
 off and adding an excess of acid to the filtrate, the isatin 
 separates in a nearly pure state. After being washed and 
 recrystallised once or twice from hot water it is quite pure. 
 It forms reddish-brown prismatic crystals, belonging to the 
 trimetric system, which are inodorous, and readily soluble 
 in alcohol, but less so in ether. Its formation from indi- 
 gotin may be thus represented. 
 
 C„Hi N ? O a + O a = 2C 8 H 5 NO,. 
 
 Indigotin. Isatin. 
 
 When isatin is heated in a tube, only a small portion 
 sublimes, the greater part being decomposed. When 
 strongly heated in the air, it burns with a brilliant flame, 
 emitting suffocating vapours, and leaving a considerable 
 amount of carbonaceous matter. 
 
 Isatin dissolves in caustic potash, forming a purple solu- 
 tion, which becomes yellow when heated, and yields on 
 cooling, potassium isatatc in the form of small hard prisms* 
 C 8 H 5 NO a + KHO = QH KNO 3 . 
 
 Isatin. Potash. Potassium 
 
 Isatate. 
 
 An aqueous solution of isatic acid may be obtained by pre- 
 cipitating the potassium compound with acetate of lead, 
 and after well washing the lead compound, suspending it in 
 water and decomposing it with sulphuretted hydrogen. 
 When the aqueous solution is evaporated in vacuo, isatic 
 acid is obtained as a white crystalline powder. If dissolved 
 in water and boiled, this acid splits up into isatin and 
 water. 
 
 When isatin is dissolved in water and heated with zinc 
 and a little sulphuric acid, the isatin combines with the 
 nascent hydrogen, and is transformed into a substance 
 called isatyde, C^HjJNLO^, which separates as a crystalline 
 powder. 
 
DERIVATIVES OF IS A TIN. 161 
 
 2C 8 H 5 N0 2 + H 2 = C 1G H 12 N 2 4 . 
 
 Isatin. Isatyde. 
 
 This, if washed and dissolved in hot alcohol, yields micro- 
 scopic crystals on cooling. Isatyde is insoluble in water, 
 and only very sparingly soluble in boiling alcohol or ether. 
 It dissolves in alkalis with a dark red coloration, which, on 
 the application of heat becomes yellow, potassium isatate 
 and hydrindin potassium being formed. When isatyde is 
 subjected to the action of heat, it turns violet brown. 
 
 If, instead of using zinc and sulphuric acid to reduce 
 isatin, sulphuretted hydrogen is employed, the isatyde as 
 soon as it is produced is converted into disulphisatyde. 
 
 C 1G H 12 N 2 4 + 2 H 2 S - C 1G H 12 N 2 2 S 2 + 2OH, 
 Isatyde. Disulphisatyde. 
 
 Disulphisatyde is a yellowish-grey tasteless powder, 
 and when treated with a solution of caustic potash, 
 becomes converted into a rose-coloured paste, which after 
 being washed with alcohol and water, consists of a mixture 
 of indi n, C 1G H 10 N 2 O, and sidphisatyde, C 1G H 12 N 2 2 S. On 
 treating this mixture with a warm concentrated solu- 
 tion of potash, it forms a black solution, which in the 
 course of a few hours becomes a semi-solid mass of black 
 needles of indin potassium, C 1G H 9 KN 2 2 . If these are 
 dissolved in boiling absolute alcohol and hydrochloric acid 
 is added, the solution as it cools deposits indin in minute 
 rose-coloured needles. It is insoluble in water, and only 
 very sparingly soluble in alcohol or ether. Nitric acid con- 
 verts it into nitrindin, and when treated with bromine it 
 yields dibromindin C 1G H 8 Br 2 N 2 2 , as a violet-black 
 powder. 
 
 Isatin combines with ammonia, with separation of water 
 giving rise to five well defined compounds.* 
 
 Imesatin C 8 H G N 2 0. 
 
 Imasatin C 1G H n N 3 O 3 . 
 
 Isamic acid C 1G H 13 N 3 4 . 
 
 * Laurent; Ann. Chim. Phys., [3] iii., 483. 
 M 
 
1 62 DYEING AND CALICO PRINTING. 
 
 Isamide Ci H u N 4 O 3 . 
 
 Isatimide CotHnNgO*: 
 
 In presence of potash or ammonia, sulphurous acid com- 
 bines with isatin to form a class of compounds called isato- 
 sidpJiiies, 
 
 Schlitzenberger, on heating isatin with hydriodic acid in 
 sealed tubes at 270 F., obtained three distinct products — 
 isato-purpurin, a red substance, soluble in alcohol and ether; 
 isato-flavin, a yellow product, insoluble in ether but soluble 
 in alcohol ; and a green compound, insoluble both in ether 
 and in alcohol. If instead of operating as above described, 
 one part of indigotin or isatin be mixed with eighty parts 
 of a cold saturated solution of hydriodic acid, and heated in 
 sealed tubes at 520° F., as was done by M. Berthelot in 
 1868, it is completely decomposed: an octane, C 8 H 18 , is 
 formed boiling at 248 F, whilst the nitrogen is trans- 
 formed into ammonia and the oxygen into water. At the 
 same time a secondary reaction gives rise to marsh gas 
 and heptane C 7 H 1G . 
 
 Although indigotic acid or nitro-salicylic acid was first 
 obtained by Fourcroy and Vauquelin, its true composition 
 was ascertained by Dumas. To prepare it from indigo, 
 2 lbs. of nitric acid, of specific gravity 1*28, is introduced 
 into a tubulated retort, to which 1 lb. of coarsely powdered 
 indigo of good quality is gradually added. Great care is 
 required in conducting this experiment, as the action is 
 very violent; the product, which floats on the surface of 
 the liquid, consisting of a small quantity of indigotic acid 
 mixed with a large quantity of a resinous substance, is 
 treated with water to dissolve the acid, and this solution is 
 returned to the acid liquor in the retort. On concentrating 
 the liquid by distillation and allowing it to cool, indigotic 
 and picric acids crystallise out. 
 
 This compound, however, is far more conveniently pre- 
 pared by the action of nitric acid on salicylic acid, 
 
NITROSALICYLIC ACID. 163 
 
 C 7 H 6 3 . This acid may be obtained by the action of 
 fused potash on salicin, or still better from the essence 
 of Gaultheria procumbens, or wintergreen, largely imported 
 from America. This essence was proved by Cahours to 
 be a compound ether, methyl salicylate, CH 3 . C 7 H 5 O s , 
 which, if heated with caustic potash, is decomposed into 
 methyl alcohol which passes off, and salicylic acid which 
 remains behind as a potassium salt. From this, salicylic 
 acid is separated on the addition of hydrochloric acid, 
 and may be purified by washing it with cold water and 
 subsequently crystallising it from boiling alcohol. By 
 the action of nitric acid it is converted into nitrosalicylic 
 acid or indigotic acid, C 7 H 6 N0 5 , or C 7 H 5 (N0 2 )0 3 . 
 
 Nitrosalicylic acid is only sparingly soluble in cold water, 
 but freely so in boiling water and in alcohol. It is easily 
 fusible, and sublimes unaltered at a somewhat higher tem- 
 perature. With persalts of iron it gives a red colouration, 
 and with salts of lead a voluminous precipitate of a pale 
 yellow colour. 
 
 When indigo is acted on by strong nitric acid the pro- 
 duct is different, picric acid, C 6 H 3 (N0 2 ) 3 0, being obtained. 
 This acid was first noticed by Hausmann in 1798. Liebig 
 gives the following method of obtaining it from indigo : — 
 one part of indigo, broken into small pieces, is very 
 gradually and cautiously added to ten or twelve parts of 
 boiling nitric acid of specific gravity 1*43. The action is 
 very violent, and if too much indigo be added at once, an 
 explosion ensues. When the whole of the indigo has 
 been introduced, more nitric acid is added, and the 
 liquid boiled until no more red fumes are given 'off. On 
 cooling, semi-transparent yellow crystals separate, which 
 are collected, washed with cold water, and then recrystal- 
 lised. It is now prepared on a very large scale from 
 phenol, and is extensively used in the dyeing of silk and 
 wool. 
 
1 64 DYEING AND CALICO PRINTING. 
 
 It crystallises in long, pale yellow, brilliant, rectangular 
 plates, which are very soluble in alcohol, ether, and ben- 
 zene, and require about eighty-five parts of cold water for 
 solution. It has an intensely bitter taste, and stains the 
 skin yellow. It has been employed in medicine as a febri- 
 fuge, but has the disadvantage that if taken for some little 
 time the skin and the whites of the eyes become yellow. 
 It gives characteristic precipitates with several of the 
 heavy hydrocarbons, such as naphthalene and anthracene. 
 Concentrated sulphuric and nitric acids dissolve it, but it is 
 precipitated again unchanged on dilution. Most of the 
 salts of picric acid are crystalline, and when heated are 
 decomposed with explosion. 
 
 Dry chlorine has no action on indigo, either at the ordi- 
 nary temperature or when heated to 21 2° F., but when 
 water is present it is readily attacked; the blue mass 
 assumes a deep orange colour, and a large quantity of 
 hydrochloric acid is given off. If the orange paste thus 
 obtained is submitted to distillation, white needles are 
 deposited in the neck of the retort, which are a mixture of 
 trichloraniline C G H 4 C1 3 N, and trichlorophenol C H 3 Cl 3 O. 
 When these products cease to be given off the mass is left 
 to cool, and the resinous orange-coloured residue is boiled 
 with water. The insoluble part consists of a brown resinous 
 substance, easily soluble in potash, from which it is pre- 
 cipitated on the addition of acetic acid. The aqueous 
 solution contains chlorisatin, dichlorisatin, and chloride of 
 ammonium, the first two of which crystallise out as the 
 liquid cools, whilst the ammonium chloride remains dis- 
 solved. 
 
 The trichloraniline and the trichlorophenol may be 
 separated by distilling them with an aqueous solution of 
 carbonate of potash, when the trichloraniline passes over 
 with the aqueous vapour, leaving the trichlorophenol in the 
 solution in the form of a potassium compound ; on cooling, 
 
CHLORISATIN.—DICHLORISATIN. 165 
 
 this separates in white crystals, which, after being purified 
 by two or three crystallisations, may be decomposed by the 
 addition of an acid. Trichlorophenol forms white flocks, 
 having a very disagreeable odour. 
 
 To effect the separation of chlorisatin from dichlorisatin 
 the crystalline mass above referred to is treated with boil- 
 ing alcohol, which dissolves out the chlorisatin and deposits 
 it again on cooling. By repeated crystallisation from 
 alcohol, the compounds may be completely separated and 
 purified. 
 
 CJrforisatin, C 8 H 4 C1N0 2 , forms transparent, orange- 
 yellow, four-sided prisms, which communicate to the skin 
 a disagreeable odour, although they are themselves in- 
 odourous. It is almost insoluble in cold, but very soluble 
 in hot water. It requires a heat of over 320 F. to decom- 
 pose it, and then gives off vapours resembling those of 
 burning indigo. When heated with a solution of potash, 
 it dissolves and behaves in a manner similar to isatin. 
 The liquid which at first is of a dark red colour gradually 
 becomes yellow, and on cooling deposits pale yellow 
 crystals of potassium chlorisatate. Chlorisatic acid, how- 
 ever, cannot be isolated, for when the salt is decomposed 
 by a strong acid it splits up into water and chlorisatin. 
 
 Dichlorisatin, C 8 H 3 C1 2 N0 2 , crystallises in needles or 
 plates, having a fine orange-red colour. Its properties are 
 similar to those of the monochlorinated compound, except 
 that it is less soluble in water and in alcohol. By the action 
 of caustic alkali, dichlorisatin is also transformed into a 
 salt. This dichlorisatic acid is more stable than that ob- 
 tained from chlorisatin, as it can be obtained in the form 
 of a yellow powder, having the formula CgHiCLNOs. It 
 cannot, however, be dried without decomposition. 
 
 When treated with ammonium sulphide, chlorisatin 
 yields a pale yellow crystalline powder, analogous to that 
 obtained by the action of reducing agents on isatin. Di- 
 
1 66 DYEIXG AND CALICO PRINTING. 
 
 chlorisatyde, C] r: H 10 N 2 Cl 2 O 4 , is only slightly soluble in 
 water, but dissolves in ammonia or other alkaline solutions, 
 communicating to them a red tint. At 356° F. it is decom- 
 posed into chlorindin, QoHgNojCLOo, and chlorisatin. 
 
 All these compounds can be more easily obtained from 
 isatin than from indigo. 
 
 When chlorisatin or dichlorisatin is dissolved in alcohol 
 and a current of chlorine is passed through it, amongst 
 the products formed there is one which contains only 
 carbon, chlorine, and oxygen, the nitrogen and all the 
 hydrogen having been eliminated. This substance, which 
 is called chloranil or perchlorquinone, C S C1 4 2 , forms pale 
 yellow lustrous scales, insoluble in water and in cold 
 alcohol, and only slightly soluble in boiling alcohol ; readily 
 in hot benzene. It is volatile without decomposition, and 
 is not acted on by nitric or concentrated sulphuric acids. 
 The action of a dilute aqueous solution of caustic potash 
 converts it into a dark red salt, potassium chloranilate, 
 K.X c CL0 4 . The addition of hydrochloric acid to an 
 aqueous solution of this compound precipitates chloranilic 
 acid in brilliant, bright red scales. They are soluble in 
 pure water with a fine violet colour. 
 
 Chloranil is also produced by the action of chlorinating 
 agents, such as potassium chlorate and hydrochloric acid, 
 on phenol, aniline, salicin, and many other benzene 
 derivatives. 
 
 Bromine forms with isatin, compounds analogous to the 
 chlorinated bodies, the formulae of which are: 
 
 Bromisatin C 8 H 4 BrX0 2 . 
 
 Bromisatinic acid C g H 3 BrX0 3 . 
 
 Dibromisatin C,H s Br„NOj. 
 
 Dibromisatinic acid B s H 4 Br 2 N0 3 . 
 
 These bodies so closely resemble the corresponding 
 chlorine compounds that it is unnecessary to give a 
 detailed description of them. 
 
ANTHRANILIC ACID. 167 
 
 The action of alkalis on indigo varies according to the 
 temperature, and the circumstances under which the reac- 
 tion takes place. In the first stage, Fritzsche states that 
 the potassium compound of a definite acid, chrysanilic 
 acid is produced; if an oxidising agent be added, anthra- 
 nilic acid is obtained, whilst at higher temperatures sali- 
 cylic acid is formed, and ultimately aniline. 
 
 Fritzsche prepares Chrysanilic acid by adding finely 
 powdered indigo to a boiling solution of caustic soda of 
 specific gravity i'45; it dissolves rapidly without giving off 
 any gas, and the liquid assumes a yellowish-red colour. 
 On concentration, yellow crystals make their appearance; 
 and on cooling, the mixture solidifies to a crystalline mass, 
 which, when dissolved in water and exposed to the air, 
 deposits indigo blue; the addition of an acid produces a 
 bulky floculent brown precipitate, which according to 
 Fritzsche is chrysanilic acid. Gerhardt,* on the contrary, 
 finds that when indigo blue is heated with potash the 
 following reaction takes place : — - 
 
 3 C lt! H 10 N,O 2 + 2KHO+ 20H 2 = 2C 16 H 1 ,N,0 2 + 2C 8 H G KN(),. 
 
 Indigotin. Indigo white. Potassium isatate. 
 
 It would appear, therefore, that Fritzsche's chrysanilic 
 acid is merely a mixture of indigo white with isatin 
 formed by the action of acids on the potassium isatate, 
 and perhaps, also, products of the further action of potash 
 on this substance. 
 
 Although the existence of chrysanilic acid is more than 
 doubtful, this is not the case with the compound called 
 anthranilic acid, phenylcarbamic acid, or meta-amidobcnzoic 
 acid, which is a constant and well defined product of the 
 decomposition of indigo under the influence of alkalis. 
 The process for the preparation of this acid is as follows : 
 Indigo blue is kept boiling in caustic potash of specific 
 gravity 1*35, water being added from time to time to 
 
 *Rev. Scient, x., 371. 
 
1 68 DYEING AND CALICO PRINTING. 
 
 replace that which evaporates. Previously to the disappear- 
 ance of the last portions of the indigo, finely pulverised 
 peroxide of manganese is added to the boiling liquid until 
 a sample of it, when diluted with water and allowed to 
 stand, no longer deposits indigo blue. It is then diluted 
 with boiling water, supersaturated with dilute sulphuric 
 acid, and filtered. The filtrate, when neutralised with 
 potash and evaporated to dryness, leaves a residue con- 
 sisting of a mixture of potassium sulphate and anthranilate, 
 with a brown colouring matter; on treatment with hot alco- 
 hol the two last are dissolved out, leaving the potassium sul- 
 phate. The spirit is now distilled off, the residue dissolved 
 in water, and a slight excess of acetic acid added, when 
 orange-coloured crystals of impure anthranilic acid are 
 deposited. These may be readily purified by recrystallisa- 
 tion from boiling water with the aid of animal charcoal ; on 
 cooling, the hydrated anthranilic acid is deposited in 
 transparent, colourless foliated crystals, with dihedral sum- 
 mits. 
 
 The formation of anthranilic acid from indigo by this 
 process admits of a simple explanation. The action of 
 potash on indigotin, as shown by Gerhardt, converts it into 
 indigo white and potassium isatate ; and the addition of 
 manganic peroxide oxidises the white indigo to indigotin 
 again, thus rendering it capable of being converted into 
 potassium isatate. The latter compound is converted into 
 potassium anthranilate thus : 
 
 C 8 H G KN0 3 + 2KHO - C 7 H 6 KN0 2 + K 2 C0 3 + H 2 . 
 
 Potassium Potassium 
 
 Isatate. Anthranilate. 
 
 Anthranilic acid has also been synthetically prepared 
 from benzoic acid by converting it first into bromonitro- 
 benzoic acid, then into bromamidobenzoic acid, and finally 
 by the action of sodium amalgam into meta-amidobenzoic 
 or anthranilic acid. 
 
 Anthranilic or phenyl-carbamic acid, C 7 H 7 N0 2 , crystal- 
 
SYNTHESIS OF INDIGO. 169 
 
 lises in colourless four or six-sided prisms, having a bitter 
 taste. It is only slightly soluble in water, but very soluble 
 in alcohol and ether. Heated at a moderate temperature, 
 it sublimes unchanged, forming white crystals similar to 
 those of benzoic acid ; but if mixed with glass and rapidly 
 heated an oily fluid distils over, which is aniline. 
 C 7 H 7 N0 2 = C 6 H 7 N + CO.,. 
 
 Anthranilic Aniline, 
 
 acid. 
 
 Aniline is formed, as before stated, when indigo is mixed 
 with hydrate of potash and distilled. By redistillation pure 
 aniline is obtained equal to about one-fifth of the weight of 
 the indigo taken. Aniline is now prepared on a^large 
 scale by the reduction of nitrobenzol by means of iron 
 filings and acetic acid. 
 
 The production of picric, salicylic, and anthranilic or 
 phenyl-carbamic acids, and especially of aniline, by the 
 action of chemical agents upon indigo, and the known 
 relation which these bodies bear to phenol and benzene, 
 produced on the minds of chemists a conviction that indi- 
 gotin in all probability might be prepared synthetically 
 from some member of the benzene series. Recently, 
 Emmerling and Engler* have succeeded in obtaining indi- 
 gotin in small quantity from the acetophenone discovered 
 in 1857 by Friedel, and which is obtained by the distillation 
 of a mixture of dried acetate and benzoate of lime. When 
 the acetophenone is acted on by fuming nitric acid, two 
 isomeric nitro-derivatives are formed, one of which is crystal- 
 line and the other syrupy; it is the latter which yields the 
 indigotin. For this purpose the syrupy modification of 
 mtroacetophenone, C 8 H 7 N0 3 , is cautiously heated in por- 
 celain basins until it solidifies on cooling to a tough resin- 
 ous mass; this is then mixed with nine parts of zinc powder 
 and one part of soda lime, and heated in small portions at 
 
 *Deut. Chera. Ges. Ber., iii., 885. 
 
170 DYEING AND CALICO PRINTING. 
 
 a time in narrow tubes over a Bunsen burner. A dark 
 coloured substance sublimes, which contains indigotin in 
 small quantity. The relation between indigotin and nitro- 
 acetophenone is shown by the following equation : — 
 2 C 8 H 7 N0 3 = C lc H 10 N 2 O 2 + 20H 2 + 2 . 
 
 Nitroacetophe- Indigotin. 
 
 none. 
 
 In the year 1865, Knop* obtained a body having the 
 formula C 8 H 7 N0 2 , to which he gave the name of hy- 
 drindic acid. This compound, which is also called 
 dioxindol, is formed from isatin or isatyde by the action 
 of sodium amalgam in the presence of water; the reactions 
 being as follows : — 
 
 C 8 H 5 N0 2 + H 2 = C 8 H 7 N0 2 . 
 
 Isatin. Dioxindol. 
 
 C 10 H 12 N 2 O 4 + H 2 = 2 C 8 H 7 N0 2 . 
 
 Isatyde. Dioxindol. 
 
 Sodium amalgam is added to isatin suspended in water 
 until the liquid becomes of a deep yellow colour, and no 
 longer gives a precipitate of isatin on the addition of 
 hydrochloric acid. On concentrating and allowing it to 
 stand, crystals of sodium dioxindol are obtained, which are 
 dissolved in water, acidulated with hydrochloric acid, and 
 chloride of barium added. The barium dioxindol thus 
 obtained is washed and put to digest in a stoppered bottle 
 with a slight excess of dilute sulphuric acid. Sulphate of 
 baryta is formed, and on evaporating the solution the 
 dioxindol is obtained in yellow needles. These crystallise 
 from hot alcohol in opaque, white, rhomboidal prisms, 
 soluble in both cold and hot water. At 270 F. it fuses 
 and begins to decompose, and at 380 F. the liquid assumes 
 a purple colour and aniline is given off. Its colourless 
 aqueous solution, on exposure to the atmosphere, becomes 
 first pink and then red, and is found to contain isatin and 
 indin. It yields easily crystallisable compounds with 
 
 *Jour. pr. Chem., xcvii., 65. 
 
OXINDOL.— INDOL. 17 1 
 
 hydrochloric and sulphuric acids, but is violently attacked 
 by nitric acid. It combines with bases. The silver salt, 
 when heated to 140 R, is decomposed, and yields benzoic 
 aldehyde, the essence of bitter almonds. 
 
 It will be seen by a comparison of the formulae that 
 hydrindic acid or dioxindol differs from indigotin by the 
 elements of water. 
 
 C 10 H ll? N 2 O 2 + 20H 2 - 2 C 8 H 7 N0 2 . 
 
 Indigotin. Dioxindol. 
 
 It seemed probable that indigotin might be obtained 
 from this compound by the removal of the elements of 
 water, and for that purpose it was heated with anhydrous 
 glycerin. Although the water was removed by this means, 
 indigotin was not produced, but a body possessing quite 
 different properties, although having the same composition. 
 Whilst indigotin is crystalline and insoluble in alcohol or 
 ether, the new isomeric substance is amorphous and soluble 
 both in alcohol and in ether, to which it communicates a 
 violet-red colour. 
 
 Dioxindol when submitted to the action of reducing 1 
 agents is transformed into oxindol. This change may be 
 effected either by treating it with tin and hydrochloric acid, 
 or which is better, wiffi sodium amalgam in an acid solu- 
 tion. Its formula is C 8 H 7 NO. It crystallises in colourless 
 needles, which are very soluble in hot water as well as in 
 alcohol and ether. It combines with bases to form salts ; 
 those of potash and soda are soluble and crystalline, whilst 
 those of the alkaline earths and metallic oxides are in- 
 soluble. 
 
 When this compound is heated in a retort with zinc 
 powder, the oxygen is removed, and a substance called 
 indol distils over, having the formula C s H 7 N. This is first 
 treated with dilute hydrochloric acid to remove any aniline 
 which may have been produced in the reaction, and then 
 dissolved in boiling water. When cold the indol crystal- 
 
172 DYEING AND CALICO PRINTING. 
 
 Uses out in brilliant colourless plates, similar in appearance 
 to those of benzoic acid. Indol may also be obtained 
 directly from indigotin by boiling it with tin and hydro- 
 chloric acid until it is converted into a yellowish-brown 
 powder, which, after being washed and dried, is mixed 
 with zinc powder and distilled. Indol then passes over. 
 According to Nencki* and Kukne,*f- indol is one of the 
 products of the action of the pancreatic juice on fibrin, 
 albumen, &c. 
 
 Indol melts at 125 R, and forms a crystalline mass on 
 cooling. It is very volatile, and although it cannot be 
 distilled alone without decomposition, yet it readily passes 
 over when heated in a current of steam. Its odour resem- 
 bles that of naphthylamine. It has weak basic properties, 
 and unites with several of the acids to form salts. It is 
 only slightly soluble in cold, but very soluble in boiling 
 water, and also in alcohol or ether. If, to an aqueous solu- 
 tion of indol an equal bulk of fuming nitric acid be added, 
 previously considerably diluted with water, a bulky red 
 precipitate is produced, which is probably a nitrate of 
 indol. A piece of pinewood dipped into an alcoholic 
 solution of indol mixed with a little hydrochloric acid, 
 acquires a cherry-red colour, which, after a short time, 
 becomes of a dirty reddish-brown. These two last reac- 
 tions of indol are so delicate that the presence of a very 
 small quantity of this substance can be easily detected. 
 
 Baeyer and Emmerlingj: have discovered a most interest- 
 ing process for converting cinnamic acid, an acid obtained 
 from oil of cinnamon, into indol. The cinnamic acid is 
 first converted into nitrocinnamic acid, 
 
 C H 8 O 2 + HNO3 = C 9 H 7 (N0 2 ) 2 + OH, 
 
 Cinnamic Nitrocinnamic 
 
 Acid. Acid. 
 
 *Deut. Chem. Ges. Ber., vii., 1593. 
 t Ibid., viii., 206. 
 X Ibid., ii., 679. 
 
INDOL. 173 
 
 which is then mixed with iron turnings and ten times its 
 weight of potassium hydrate, and heated until the potash 
 fuses. When cold the mass is dissolved in water and the 
 solution agitated with ether : this dissolves the indol and 
 a small quantity of aniline which is produced at the same 
 time. On evaporating the ethereal solution, these two 
 bodies are left, and the aniline may be removed by treat- 
 ment with a little dilute hydrochloric acid. In this reac- 
 tion the indol is produced from the nitrocinnamic acid by 
 the simultaneous removal of carbonic anhydride and oxy- 
 gen, by the potash and iron respectively. 
 
 C 9 H 7 NC>4 = C 8 H 7 N + CO, + O* 
 
 Nitrocinnamic Indol. 
 
 Acid. 
 
 Baeyer and Emmerling* have also recently discovered a 
 method by which isatin can be reconverted into indigotin, 
 one of the most important problems in connection with 
 the chemistry of these compounds. For this purpose 
 isatin is added to about fifty times its weight of a mix- 
 ture of equal parts of phosphorus trichloride, with chloride 
 of acetyl containing phosphorus in solution, and heated in 
 sealed tubes by means of a water bath to a temperature of 
 about 1 75° F. The chlorides of phosphorus and acetyl 
 act as solvents for the phosphorus, which removes the oxy- 
 gen from the isatin. The green fluid produced in this 
 reaction is poured into a large quantity of water, and after 
 being exposed to the air in shallow vessels for twenty-four 
 hours, deposits a blue precipitate. This is a mixture of 
 two colouring matters, one of which is red and soluble in 
 alcohol, which they call indigo-purpurin ; whilst the other, 
 which is blue and insoluble, presents all the characters of 
 indigotin. 
 
 According to Bolley and Crinsoz,-f* when Bengal indigo 
 is heated between two watch glasses, a small quantity of 
 
 * Deut. Chem. Ges. Ber., iii., 514. 
 + Technologiste, xxviii., 194. 
 
174 DYEING AND CALICO PRINTING. 
 
 golden-yellow needles are sublimed before, the indigotin. 
 If these arc removed they are found to be only slightly 
 soluble either in hot, or in cold water. They are slightly 
 soluble in alcohol, communicating to it a yellowish-green 
 colour. The compound, which contains no nitrogen, is 
 neutral to test paper, and is not acted on by a mixture of 
 sulphuric acid and bichromate of potash. 
 
CHAPTER VI. 
 
 INDIGO — CONTINUED. 
 
 Indigosulphonic acids. — There are two commercial pre- 
 parations obtained by the action of sulphuric acid on 
 indigo, the first of which bears the name of sidpJiopiupuric 
 acid. It may be made by adding one part of good com- 
 mercial indigo, very finely pulverised, or, better still, puri- 
 fied indigo, to four parts of highly concentrated sulphuric 
 acid, and heating the mixture for a short time, varying from 
 half an hour to an hour, or until a small quantity mixed 
 with a large quantity of water gives a deep blue colour. 
 Great care must be bestowed on this part of the operation 
 so as to avoid the formation of another compound called 
 sulphindigotic acid, which will be described presently. 
 The purple mass thus produced, as soon as it is found to 
 be soluble, is thrown into forty or fifty parts of water, 
 when a beautiful purple precipitate is produced. This is 
 collected on a filter and slightly washed with dilute hydro- 
 chloric acid so as to remove the various impurities which 
 the indigo employed may have contained, and also any 
 small amount of sulphindigotic acid which may have been 
 produced. 
 
 Sulphopurpuric acid communicates a bluish-purple 
 colour to water, in which it is only slightly soluble. When 
 carbonate or acetate of soda is added to this solution 
 purple flocks are precipitated, which are, however, soluble 
 in a large quantity of water. It also gives precipitates 
 with salts of lime, alumina, and iron. It is not acted 
 on at the ordinary temperature by strong caustic alkali. 
 
i;6 DYEING AND CALICO PRINTING. 
 
 The aqueous solution of this acid is decolorised by 
 reducing agents, such as zinc, sulphuretted hydrogen, and 
 chloride of tin ; it becomes blue again, however, on expo- 
 sure to the air. 
 
 Sulphopurpuric acid is converted into sulphindigotic acid 
 when heated with eight or ten parts of sulphuric acid ; or 
 the latter may be manufactured directly from indigo, by 
 heating very carefully one part of finely pulverised colour- 
 ing matter with ten or twelve parts of concentrated com- 
 mercial sulphuric acid, or, better, with six to seven parts of 
 Nordhausen acid, to a temperature of 120° F. for several 
 hours. The operation is complete when a small sample is 
 found to be entirely soluble in water. The heated mass is 
 then allowed to cool and dissolved in fifty parts of water; 
 the solution should be of a pure blue colour, the more purple 
 it is the more sulphopurpuric acid it contains. After being 
 allowed to stand for some time to allow any impurities that 
 it may contain, and any sulphopurpuric acid which may 
 have been formed, to deposit; a beautiful blue solution is ob- 
 tained which contains sulphindigotic acid, mixed with small 
 quantities of hyposulphindigotic acid. Excess of strong 
 caustic alkali decomposes sulphindigotic acid, yielding a 
 yellow liquid, but with weak alkalis it combines to form 
 sulphindigotates. These, when solid, are of a beautiful 
 bronze-blue colour, and dissolve freely in water, yielding 
 blue solutions. They are, however, only very slightly 
 soluble in neutral saline solutions, such as sulphate of soda 
 or the chlorides of sodium and potassium, so that if 
 these salts are added to a solution of an alkaline sulph- 
 indigotate, the latter is precipitated in blue flakes. 
 
 The following table gives the comparative solubility of 
 
 the principal sulphindigotates: — 
 
 . , ) Soluble in one hundred and 
 
 Sulphindigotate of potash 
 
 forty parts of water. 
 Sulphindigotate of soda Slightly more soluble. 
 
HYPOSULPHINDIGOTIC ACID. 
 
 177 
 
 ates of lime, ) 
 
 , , . > Very soluble, 
 and alumina ) J 
 
 c , ,. ,. , , r , ( Very slightly soluble in cold, 
 
 Sulphindigotate of baryta \ , , , 
 
 ( more soluble in hot water. 
 
 Sulphindigotates of lime, 
 
 magnesia, 
 Sulphindigotate of lead Insoluble. 
 
 Both acid and salts are decolorised by reducing 
 agents. 
 
 A third sulphonic acid exists, called hyposnlphindigotic 
 acid, which is always formed to a certain extent in the pre- 
 paration of sulphindigotic acid ; it is not, however, of any 
 commercial importance. To separate the two acids and 
 obtain them in a pure state, a piece of flannel which has 
 been thoroughly washed first with soap and carbonate of 
 soda, and then with pure water, is digested in a solution of 
 the ordinary sulphindigotic acid until all the colouring 
 matcer is taken up. The dyed flannel is then well washed 
 to remove the excess of free sulphuric acid, after which it is 
 treated with a weak solution of carbonate of ammonia in 
 order to dissolve the acids off the flannel. The blue solu- 
 tion thus obtained is evaporated to dryness at a tempera- 
 ture of 120 F., and the residue treated with alcohol of 
 specific gravity o - 83, which dissolves the hyposulphindigo- 
 tate of ammonia and leaves the sulphindigotate. 
 
 All three acids can be obtained in a state of purity by 
 precipitating the solutions of their respective alkaline salts 
 with acetate of lead, and decomposing the insoluble lead 
 compounds, after they have been carefully washed, by a 
 current of sulphuretted hydrogen : sulphide of lead is 
 formed and a colourless fluid remains, which, when evapo- 
 rated in contact with the air becomes blue, and leaves an 
 amorphous residue. The acids, which when dry have a 
 slightly astringent acid taste, are very soluble in water 
 and alcohol. The formula of sulphopurpuric acid is 
 C 16 H 9 N 2 O a . HSO3, and that of sulphindigotic acid 
 C 8 H 4 NO. HSO § , 
 N 
 
i; 8 DYEING AND CALICO PRINTING. 
 
 The sulphindigotic acid of commerce known as 'Saxony- 
 blue,' is chiefly used by woollen dyers, who add to the dye- 
 beck a little alum and cream of tartar, which helps to fix 
 the indigo on the wool. The green colouring matter 
 which it generally contains is not objectionable in this in- 
 stance, as it has no affinity for woollen fibre ; for dyeing 
 silk, however, the green matter must be removed. This is 
 effected by converting the acid into an impure sulphindigo- 
 tate of soda, which is known in commerce as indigo 
 carmine. It may be prepared as follows: I lb. of very 
 finely pulverised indigo of the best quality* (or, better still, 
 refined indigo), sieved and carefully dried at a temperature 
 of 150 to 160 F. is put into an earthenware vessel placed 
 in cold water to prevent any rise of temperature. To it, 
 6 lbs. of sulphuric acid of specific gravity 1*845 is carefully 
 and gradually added, the mixture being kept well stirred 
 during the whole time. The mass is then put in a closed 
 vessel and removed to a stove, where it is kept at a 
 moderate temperature for several days, after which it is 
 dissolved in 5 gallons of water, and a saturated solution 
 of common salt added until the whole of the blue colouring 
 matter is precipitated. The supernatant liquor, which has 
 a dark green colour, is drawn off, and the precipitate is then 
 thrown on a woollen filter and washed with water until the 
 liquid which passes through has a slightly blue tint. By this 
 means an ordinary quality of carmine is prepared, but if a 
 first class quality is required, perfectly free from green 
 colouring matter, it is necessary to operate as follows : 
 The carmine prepared in the manner described is dissolved 
 in a mixture of 5 gallons of water and 1 lb. of sulphuric 
 acid ; the sulphuric acid is then carefully neutralised with 
 carbonate of soda, and the whole of the carmine precipi- 
 
 * To obtain the indigo in a sufficiently minute state of division it is intro- 
 duced into a cylinder along with some cast iron shot, and the cylinder is then 
 caused to revolve rapidly. 
 
IXDIGO CARMIXE. 
 
 1/9 
 
 tated by a solution of salt. The precipitate, after being 
 thrown on a filter and drained, is again dissolved and 
 reprecipitated, this operation being repeated until the green 
 matter is entirely removed, which may be known by the 
 supernatant liquid no longer having a green tint. It is 
 then washed with water until the liquid comes through 
 blue, when it is drained as far as possible, and finally sub- 
 mitted to slight pressure in linen bags : it is now ready 
 for the market. To ascertain if the green colouring matter 
 is removed, a small quantity of the carmine is rubbed on a 
 piece of glazed paper. When the colour dries, it gives a 
 shade varying from a pale blue to a rich coppery purple, 
 according to the mode of manufacture employed; and if 
 any green colouring matter be left it will show itself as a 
 green ring round the blue circle. One pound of indigo 
 yields ten pounds of good carmine. 
 
 Another process for the preparation of indigo carmine 
 has been patented by Messrs. L. and E. Bailey, by which 
 it is stated a fine purple carmine can be obtained. They 
 fuse fifteen parts of dry bisulphate of soda in an iron pot, 
 and add to it one part of good indigo, in small quantites 
 at a time, taking care to constantly stir the mass, which 
 swells considerably. The application of heat is continued 
 until a small quantity taken out is found to be entirely 
 soluble in water; the fused mass is then allowed to cool, 
 dissolved in seventy or eighty parts of water, and two 
 parts of common salt are added for every part of the mix- 
 ture, to precipitate the carmine. It is finally washed with 
 a weak solution of common salt and dried. Bailey's blue 
 forms purple crystalline masses, which give a very bright 
 violet-blue solution. It is soluble in hot concentrated 
 acetic acid, from which it is deposited on cooling in bril- 
 liant coppery crystals. 
 
 The three following analyses will show the composition 
 of these carmines: — 
 
I So DYEING AND CALICO PRINTING. 
 
 Best. 2nd quality. 3rd quality. 
 
 Colouring matter 12*4 io - 2 4-96 
 
 Saline residue 139 4'S 570 
 
 Water 737 85-0 89-34 
 
 IOO'O IOO'O ioo - oo 
 
 To ascertain the value of any of these sulpho com- 
 pounds of indigo, a given weight is dissolved in water, a 
 little cream of tartar and alum added, and the colour 
 removed by dyeing wool. The value of the sample is in 
 proportion to the weight of wool dyed and the intensity of 
 shade produced. 
 
 Berzelius has studied some of the modifications which 
 the sulphonic acids of indigo undergo when subjected to the 
 action of alkalis and alkaline earths, and his results show 
 that they yield under such influence, yellow, red, green, and 
 violet compounds, which have the power of dyeing wool 
 without a mordant. This illustrious chemist found that 
 when a solution of barium hyposulphindigotate is evapo- 
 rated in a water bath it leaves a green residue, which is 
 very soluble in water and alcohol, and gives a greenish- 
 grey precipitate with subacetate of lead. When this lead 
 compound is decomposed by sulphuretted hydrogen, it 
 yields a solution of sulpJioviridic acid, which is green by 
 reflected light and dark red by transmitted light. 
 
 When potassium sulphindigotate is mixed with lime 
 water, and gently heated in an open vessel, it becomes red 
 and afterwards yellow. If, as soon as the liquid has 
 become red, the excess of lime be removed by means of a 
 current of carbonic acid, and the clear solution evaporated, a 
 brown residue is obtained, which, when treated with alcohol 
 of specific gravity '82, yields a yellow extract and an 
 insoluble residue. The alcoholic solution is now precipi- 
 tated with acetate of lead, and the insoluble lead com- 
 pound, after being washed, is suspended in water and de- 
 
SULPHONIC A CIDS FROM INDIGO. 1 8 1 
 
 composed by sulphuretted hydrogen ; the solution, when 
 filtered from the lead sulphide and carefully evaporated, 
 leaves a crystalline compound, to which Berzelius gave the 
 name of sulphoflavic acid. If the residue insoluble in 
 alcohol, is dissolved in water, precipitated by a salt of lead, 
 and the precipitate decomposed by sulphuretted hydrogen, 
 a solution is obtained which on evaporation yields a red 
 amorphous compound, sulphoriific acid. 
 
 If thirty parts of lime water be heated with one part of 
 potassium sulphindigotate in a close vessel, it assumes a 
 splendid purple colour, and when precipitated with lead 
 and treated in a manner similar to that just described, a 
 brown amorphous body is obtained, to which Berzelius 
 gave the name sulphopurpuric acid. 
 
 M. Gros-Renaud has also made a similar series of ex- 
 periments. One of the results which he obtained deserves 
 notice. On adding caustic soda of specific gravity 1*35 to 
 sodium sulphindigotate, the liquor becomes yellow, and a 
 black precipitate is formed, which is soluble in pure water. 
 The yellow liquor undergoes a gradual change on being 
 kept. If it is saturated with sulphuric acid a few hours 
 after it has been prepared, it gives a blue colouration. If 
 the acid is added after twenty-four hours, the liquid 
 assumes a green tint, which gradually becomes violet; 
 whilst after forty-eight hours it assumes an intense red 
 colour under these circumstances. If this liquid be now 
 partially neutralised with carbonate of soda, it imparts to 
 wool a colour varying from pink to crimson-purple, accord- 
 ing to the temperature and concentration of the bath. 
 This product differs in many respects from sulphopurpuric 
 acid. It is far more soluble in water, and on the addition 
 of caustic alkali becomes yellow immediately. Wool dyed 
 with this acid yields a red colour to sulphuric acid, whilst 
 sulphopurpuric acid yields a blue. 
 
 If a solution of sulphindigotic acid be left in contact 
 
1 82 DYEING AND CALICO PRINTING. 
 
 with caustic soda of specific gravity 1*35 for three days, 
 and it is then supersaturated with concentrated sulphuric 
 acid, it gives a yellow liquid and a yellowish-brown precipi- 
 tate. The latter, when collected and washed, imparts to 
 wool light or dark yellow shades, according as the precipi- 
 tate has been more or less washed. 
 
 When indigotin is acted on by certain chemical reagents 
 it becomes converted into a colourless substance, which has 
 received the name of white indigo. To explain this reac- 
 tion two theories have been proposed. According to the 
 one, the white indigo is a hydride of the blue; according 
 to the other, the indigo blue is an oxide, and the white 
 indigo a hydrate of a body containing less oxygen than 
 the blue. 
 
 The following formulae illustrate these two hypotheses: 
 
 Indigotin C 16 H 10 N 2 O 2 . 
 
 Indigo white C 16 H 10 N 2 2 .H 2 . 
 
 Indigotin C 10 H 10 N 2 O.O. 
 
 Indigo white C 10 H 10 N 2 O..OH 2 . 
 
 The best process yet devised for the preparation of this 
 white indigo was published by Dumas some years ago: 
 1 lb. of finely powdered indigo is introduced into a closed 
 vessel with 3 lbs. of ferrous sulphate (green vitriol), 3 lbs. 
 of slaked lime, and about 2 gallons of water ; the mixture 
 being shaken up from time to time during two days, and 
 finally allowed to settle. The pale yellow liquor is then 
 syphoned off into bottles filled with carbonic acid, at the 
 bottom of which is some hydrochloric acid deprived of air by 
 boiling. As the alkaline solution is run into the bottle, the 
 hydrochloric acid combines with the lime, and white indigo 
 is precipitated. Care must be taken that the bottles are 
 quite full of liquid. After standing some time the preci- 
 pitate is thrown on a filter under a bell-jar filled with car- 
 bonic acid, washed with cold water, thoroughly deprived 
 of air by ebullition, and then dried in vacuo. 
 
WHITE INDIGO. 183 
 
 As thus prepared, it is a greyish-white amorphous body, 
 tasteless and inodorous, and having a silky lustre. It is in- 
 soluble in water and dilute acids, but soluble in alcohol and 
 ether, and in solutions of the alkalis and alkaline earths. 
 These solutions have a yellow tint, but in contact with the 
 air they gradually become blue owing to the re-formation of 
 indigotin : oxidising agents produce the same effect. When 
 heated out of contact with the air, a small quantity of 
 indigotin sublimes and a carbonaceous mass is left. Con- 
 centrated sulphuric acid dissolves it with intense purple 
 colouration, and on the addition of water yields sulphin- 
 digotic acid. Its alkaline solutions give bulky white 
 precipitates with salts of magnesia, zinc, alumina, and 
 protoxides of iron, manganese, lead, and tin, whilst with 
 cupric and ferric salts it is immediately converted into 
 indigotin. The precipitate which is produced with protox- 
 ide of tin is extensively employed, as will be seen further 
 on, for printing indigo on fabrics. If this tin compound be 
 heated, it yields metallic tin and a sublimate of indigotin. 
 White indigo forms two compounds with lime, one soluble, 
 the other insoluble. According to Lowig, the lead com- 
 pound deflagrates slightly, leaving metallic lead. 
 
 A great variety of substances have the property of 
 reducing indigotin. 
 
 1. There are the alkali metals which decompose water, 
 the liberated hydrogen combining with the indigotin, whilst 
 the alkali formed at the same time dissolves the white 
 indigo produced. This result is more easily obtained with 
 the amalgams of the metals than with the metals them- 
 selves. 
 
 2. Certain metals and metalloids in a boiling alkaline 
 solution also reduce indigotin. Such are zinc, tin, anti- 
 mony, aluminium, and phosphorous. 
 
 3. Certain metallic oxides capable of a higher degree of 
 oxidation. 
 
1 84 DYEIXG AND CALICO PRINTING. 
 
 4. Certain acids susceptible of further oxidation, such as 
 phosphorous acid, hypophosphorous acid, and especially 
 hyposulphurous acid, H 2 SO 2 . Their action is the same 
 in presence of alkalis. 
 
 5. Certain phosphides, arsenides, and sulphides, especially 
 sulphide of arsenic. 
 
 6. Certain organic substances in presence of an alkali, 
 such as glucose and gallic acid. 
 
 7. Certain fermentations in presence of an alkali, such as 
 the butyric fermentation. 
 
 Among the compounds which are used on a practical 
 scale for reducing indigo in the presence of alkalis, are 
 protoxide of iron from the sulphate, protoxide of tin com- 
 bined with alkali, or protochloride of tin, tersulphide of 
 arsenic, glucose, and certain special fermentations. 
 
 A method of preparing an indigo vat which gives very 
 satisfactory results has been recently introduced by 
 Schiitzenberger and Lalande.* It depends upon the 
 extraordinary reducing power possessed by the salts of the 
 true hyposulphurous acid, H 2 S0 2 . Schiitzenberger, *f" some 
 years ago, found when zinc was introduced into an aqueous 
 solution of sulphurous acid, that it dissolved without evolu- 
 tion of hydrogen, and the yellow liquid thus produced, 
 contained zinc hyposulphite, possessed remarkable decolor- 
 ing powers. In the method adopted for applying this 
 reaction to the preparation of an indigo vat, a solution of 
 acid sodium sulphite (bisulphite) of about 30° Baume is 
 agitated in a closed vessel with granulated zinc for about an 
 hour, after which it is drawn off and mixed with a slight 
 excess of milk of lime so as to precipitate the zinc which 
 is in solution. To the clear liquid, containing sodium and 
 calcium hyposulphites, finely powdered indigo is added, 
 and a sufficient quantity of lime or soda to dissolve the 
 
 * Chem. Centr., 1873, P- 735- 
 t Zeits. Chem. [2] v., 545. 
 
SCHUTZENBERGER'S PROCESS. 
 
 18$ 
 
 white indigo produced by the powerful reducing action of 
 the hyposulphite on the indigotin. As in the ordinary vats, 
 cotton is dyed cold, whilst for woollens the vat should be 
 warm. One pound of indigo to 1 gallon or 1 J^ gallons of the 
 solution forms a very concentrated vat. A new method of 
 printing, which gives finer shades and sharper definitions 
 than the old one, has been also introduced, employing a 
 concentrated solution of indigo reduced with a large excess 
 of the hyposulphite, and thickened in the usual way. For 
 oxidation the pieces are hung out for twelve or fourteen 
 hours, and then washed and soaped. The annexed specimen 
 was kindly furnished by Messrs. Edmund Potter and Co., 
 of Manchester. 
 
 SCHUTZENBERGER AND LALANDE's PROCESS. 
 
 The printing of reduced indigo is from time to time 
 employed in printworks to produce certain styles of prints. 
 To effect this, protochloride of tin is added to indigo 
 which has been reduced by sulphate of iron in the manner 
 previously explained (p. 182). A white precipitate is thus 
 produced, which is collected and filtered as far as possible 
 out of contact with air; or, a mixture of finely pulverised 
 indigo, caustic soda, and protochloride of tin are heated 
 together until the indigo is reduced, and hydrochloric acid 
 is then cautiously added so as to precipitate the compound 
 of white indieo and tin. 
 
1 86 DYEIXG AND CALICO PRINTING. 
 
 The precipitate is washed, carefully mixed with gum, 
 and printed in the usual manner; but it is necessary to 
 conduct the operations as rapidly as possible, since all 
 the white indigo, transformed into indigotin before pene- 
 trating the fibre, is lost to the printer. To facilitate the 
 absorption of the white indigo by the fibre, the goods are 
 passed through milk of lime after being printed; this 
 decomposes the chloride of tin, and the liberated white 
 indigo attached to the fibre gradually changes from a pale 
 green to a blue colour. The pieces are then thoroughly 
 washed, and passed in a weak bath of sulphuric acid to 
 completely fix the indigo in the fabric. 
 
 Some years ago, Messrs. Thomas Hoyle and Sons pro- 
 duced some very good specimens of this class of work. 
 Their success was due to an ingenious method of protect- 
 ing the reduced indigo from the action of the air, by 
 introducing a current of coal gas into the machine, near 
 the printing cylinder. After a little while, however, they 
 gave up its use, owing to the deleterious influence of the 
 coal gas on the health of the workmen. 
 
 The chief application of reduced indigo has been for a 
 class of work called chintzes, which require to have fast 
 reds, blues, greens, and yellows. To produce these colours 
 the pieces are first dyed in madder to produce the reds, 
 and the other colours are blocked in. This latter opera- 
 tion is slow and costly, many printers have therefore tried 
 to print the madder mordants at the same time as the 
 reduced indigo and tin. The results generally obtained 
 have been unsatisfactory, as the oxide of tin was but im- 
 perfectly removed, and the portion which remained, fixed 
 a certain quantity of alizarin when the pieces were dyed 
 with madder. Owing to this, a dirty purple shade was 
 communicated to the blues and an olive tint to the greens. 
 
 The late Mr. J. Lightfoot, of Accrington, overcame this 
 difficulty some time ago, by carefully avoiding any excess of 
 
LIGHTFOOTS PROCESS. 
 
 187 
 
 oxide of tin in the preparation of his reduced indigo com- 
 pound, for he found by experiment that it was only when 
 the tin was in excess that it injured the colours. Accord- 
 ing to the specification of his patent, taken out in Decem- 
 ber, 1867,* he takes the following proportions: — 1% lbs. 
 of dry finely powdered indigo, or an equivalent quantity of 
 indigo pulp, i}£ lbs. of tin crystals, and a gallon of soda 
 or potash ley are boiled together ; a gallon of boiling 
 water is then added, and the whole allowed to cool. 
 Eight ounces of sugar, or a pound of treacle are dis- 
 solved in 3 gallons of water, and the prepared indigo 
 liquor poured into it. Three quarts of acetic acid, 
 at 8° Twaddle, or 2^ pints of hydrochloric acid, or 
 1 pint of sulphuric acid, previously diluted with 1 pint of 
 water, are now added. A precipitate is thrown down, which 
 is a compound of white indigo and protoxide of tin. This 
 is filtered until there is only a gallon left on the filter. To 
 make this pulpy mass ready for printing, it is thickened 
 with 3 or 4 lbs. of gum Senegal or other thickening mate- 
 rial, which is stirred in until it is dissolved. He also states 
 that oxide of tin dissolved in alkali, or powdered or granu- 
 lated tin, may be substituted for the crystals of chloride 
 of tin. The accompanying beautiful specimen, produced 
 by this process, we owe to the kindness of Messrs. F. W. 
 Grafton and Co., of Manchester. 
 
 lightfoot's process. 
 
 No. 3,663. 
 
1 88 DYEING AND CALICO PRINTING. 
 
 As the fixing of colours by the use of steam is becoming 
 every day more important, the discovery of a good 
 process for the printing of indigo to be fixed by steam 
 would be very valuable, but all attempts to effect this 
 practically have failed up to the present time. M. E. 
 Schlumberger has devised a process which fixes the colour, 
 but is too costly to be carried out practically on a large 
 scale. It consists in mixing together 
 
 Indigo, very finely ground, with water (twenty ) 
 parts of indigo to eighty of water) j" 4 P 
 
 Fused cyanide of potassium 4 ,, 
 
 Hydrate of oxide of tin in paste 4 „ 
 
 Gum water 13 „ 
 
 This mixture is printed and steamed. Under the action 
 of steam the cyanide of potassium is decomposed into 
 potash and prussic acid, and the indigo being reduced by 
 the oxide of tin is dissolved by the alkali and becomes 
 fixed on the fabric. 
 
 It is important for the printing of indigo, as well as for 
 the preparation of the sulpho compounds previously de- 
 scribed, to employ indigo as pure as possible. The 
 following is a brief description of the two processes now 
 commercially employed to prepare what is called refined 
 indigo:— The first process consists in heating indigo with 
 dilute hydrochloric acid, to dissolve the lime and other 
 mineral matters, as well as any starch that it may contain, 
 after which it is well washed and boiled with a weak solu- 
 tion of caustic soda to remove chlorophyll and resinous 
 impurities. It is finally washed, pressed, and dried. The 
 second process was devised by the author, many years ago, 
 for Messrs. Haas and Co., now settled in Leeds, and is 
 founded on the principle of first converting the indigotin of 
 the commercial indigo into white indigo and then reoxi- 
 dising it in the air. This is effected by placing in a vat one 
 part of finely pulverised indigo, two parts of green copperas 
 
COMMERCIAL INDIGOS. 189 
 
 (ferrous sulphate), and two hundred parts of water con- 
 taining 10 per cent, of caustic soda. Steam is turned in, 
 and the whole kept at the boil for a short time, and then 
 allowed to cool. The clear liquor is run out and exposed 
 in shallow leaden vats to the atmosphere, when the soluble 
 white indigo is oxidised to indigotin, which is precipitated 
 in a nearly pure state. 
 
 Having briefly noticed the properties of indigotin and 
 its derivatives, and some of their applications, the next 
 things to be considered are the characters of commercial 
 indigo, and its application in print and dyeworks. The 
 manufacture of this article in Bengal has already been 
 pretty fully described, so that it will merely be necessary 
 to give an outline of the general characters presented by 
 commercial indigos as imported into this country. Although 
 it is very difficult, by any verbal description, to convey a 
 correct idea of the difference in appearance between the 
 many varieties of indigo, yet an attempt may be made to 
 give some notion of the aspect of the different kinds of 
 Bengal indigo, as they are by far the most important, and 
 include all qualities, from the best and finest that come 
 into the market to very ordinary indigo. 
 
 When it has not sustained any damage, Bengal indigo is 
 generally imported in the form of large prismatic pieces, 
 packed in cases holding from 1*4 to 2 cwt. The best 
 qualities have a dark violet-blue colour, and take a 
 beautiful coppery lustre on being rubbed with the nail; 
 they produce a sensation of dryness on the tongue; 
 they are easily powdered, and form a fine uniform 
 paste. This kind, however, never contains more than 72 
 per cent, of pure indigotin, and is characterised by its 
 comparatively low specific gravity, which is but little more 
 than 1-3. 
 
 The next qualities are the violet-red indigos of purple 
 hue, with fracture more uniform and lustrous, and they are 
 
190 DYEIXG AXD CALICO PRINTING. 
 
 heavier and harder. The red shade is caused by the 
 presence of a large quantity of brown and red extractive 
 matter. It is amongst these qualities that the indigos 
 giving the finest colours are found, for it would appear that 
 both the brown and red of the indigo take a certain part 
 in the dyeing process ; probably they dissolve and are fixed 
 on the cloth along with the indigo, strengthening the 
 shades. Most dyers prefer these red indigos to the first 
 qualities. 
 
 Again, there are qualities of a lighter blue, poorer in 
 colouring matter, but containing also less extractive matter. 
 The impurities consist of mineral matter. They are lighter, 
 do not show the strong coppery lustre of the other two 
 qualities, and produce more strongly the sensation of dry- 
 ness when touched with the tongue. The worst qualities 
 both of Bengal and all other kinds of indigo, are those 
 which are of a light blue colour, approaching to grey or 
 green. This colour denotes the presence of a large 
 quantity of extractive matter of a different kind to the 
 indigo brown which characterises the red varieties. These 
 indigos are hard, heavy, do not give a copper}' reflection, 
 and when touched with the tongue produce very strongly 
 the sensation of dryness. 
 
 There are no fewer than forty-three recognised varieties 
 of Bengal indigo, but as it is impossible to enter into 
 a detailed account of each of these in a work like 
 this, an idea of the difference in appearance between 
 the good and bad qualities may be gained from the 
 above short description of the three principal varieties. 
 There have been several methods devised by chemists to 
 determine the relative commercial value of this valuable 
 dye ; but before describing them it may be as well to give 
 the following analysis made by Chevreul, which shows the 
 composition of a fair quality of commercial indigo dried at 
 212° F. 
 
TESTING INDIGO. 191 
 
 Indigotin 45 
 
 Matters soluble in alcohol 30 
 
 Matters soluble in ether 12 
 
 Resin soluble in hydrochloric acid 6 
 
 Mineral matters 7 
 
 100 
 
 The quantity of hygroscopic water should not exceed 
 6 per cent. Berzelius found that the portion soluble in 
 alcohol and ether consisted chiefly of four substances, 
 indigo red (indirubin of Schunck), indigo brown (the indi- 
 humin of Schunck), gluten, and chlorophyll. 
 
 Both organic and inorganic substances are used for the 
 adulteration of indigo. The mineral matters usually added 
 are artificially dyed clay or sand. Starch, Prussian blue, &c, 
 are also employed. 
 
 To detect these adulterations 100 grains of indigo, after 
 being dried at 21 2° F. to ascertain the amount of moisture, 
 is placed in a small earthenware dish and gradually heated 
 to redness. The carbonaceous mass thus formed is taken 
 out, powdered, and again heated until all the carbon is 
 burnt off. The weight of the ash remaining is then ascer- 
 tained, and should not exceed ten per cent. In a pure 
 indigo, the ash is composed of phosphate and carbonate of 
 lime, potassium sulphate, chloride of potassium, silica, and 
 a small quantity of oxide of iron. To ascertain if starch 
 is present, 100 grains of indigo are pulverised and boiled 
 with very dilute hydrochloric acid ; the clear solution yields 
 a beautiful purple colour on adding a few drops of tincture 
 of iodine. 
 
 A far more important matter to the consumer, however, 
 is to ascertain the exact amount of colouring matter 
 (indigotin) which a commercial indigo contains. Although 
 the general characters already mentioned as indicating the 
 various qualities of indigo may be sufficient to give the 
 
192 DYEING AND CALICO PRINTING. 
 
 broker a fair idea of their value, yet, it is always advisable 
 where large quantities are employed, to ascertain by direct 
 analysis their comparative value. 
 
 The methods of determining the dyeing power of an 
 indigo can be grouped into four distinct classes. 
 
 The first consists of one process only, and was introduced 
 many years ago by a French manufacturer, M. Lubil- 
 lardiere. Ten grains of pure indigotin, and the same weight 
 of the sample to be tested are each carefully dissolved in 
 eight or ten parts of concentrated sulphuric acid, and the 
 solutions made up with water to I quart. Equal volumes 
 of these solutions are then placed in graduated tubes, and 
 water is gradually added to the indigotin solution until it 
 has the same intensity of colour as the indigo to be tried. 
 The amount of indigotin present in the latter is in inverse 
 ratio to the amount of water added. Thus if ioo volumes 
 of the indigotin solution requires 1 38"! volumes of water to 
 bring it down to the same tint as the other, the proportion 
 will be 
 
 2381 : 100 : : 100 : 42. 
 
 This process is defective, because the colouring power of 
 such a solution is so great, that it requires a large amount 
 of dilution before the liquid is sufficiently transparent for 
 the operator to form a correct judgment of the intensity 
 of shade, and also because some of the other matters in the 
 indigo influence the colour to a certain extent. 
 
 The second class is based on the complete oxidation of 
 indigotin. The substances used for this purpose are, 
 bleaching powder, proposed by Chevreul ; permanganate of 
 potash, proposed by Lefort; chlorate of potash and hydro- 
 chloric acid, proposed by Bolley; and bichromate of potash 
 and sulphuric acid, proposed by Penny. To ascertain the 
 value of an indigo by any of these processes a known weight 
 of the indigo to be tested is finely pulverised, and dissolved 
 in concentrated sulphuric acid. When the solution is com- 
 
TESTING INDIGO. 193 
 
 pletely effected, water is added. A solution of pure indigotin, 
 of known strength, is prepared in a similar manner, and 
 by gradually adding to a certain volume of this a solution 
 of the oxidising agent, the amount required to decolorise 
 the solution is readily ascertained. The solution of 
 indigo to be tested is then treated in a similar manner. 
 The quantity of the oxidising solution required in the two 
 operations will be directly proportional to the amount of 
 indigo present. 
 
 The details of Penny's method are as follows: 10 grains 
 of the sample of indigo to be tested are finely pulverised, 
 and introduced into a small flask with 120 grains of sul- 
 phuric acid of specific gravity i'845. The flask is then stop- 
 pered and placed in a water bath, and the whole is main- 
 tained at a temperature of 120 F. for several hours; some 
 broken glass or garnets being added to facilitate the mix- 
 ture of the indigo and acid when the vessel is shaken. Great 
 care must be taken to ensure the perfect solution of the 
 indigo in the acid. As soon as this is effected, the blue liquid 
 is poured out, and the flask washed out with water ; a 
 sufficient quantity being employed to make up the solution 
 to a pint. It is then transferred to a beaker and ^ of an 
 ounce by measure of strong hydrochloric acid is added. 
 Pure dry bichromate of potash is dissolved in water and made 
 of such strength that an alkalimeter of 1,000 grains con- 
 tains 7 - 5 grains of the salt. This solution is added succes- 
 sively, in small quantities, to the dilute sulphate of indigo 
 solution, until a drop of the mixture on being placed on a 
 white slab or on bibulous paper presents a distinct brown 
 or ochrous shade, unmixed with any blue or green. The 
 process is now finished, the number of measures is read off", 
 which gives the per centage of indigotin in the indigo sub- 
 mitted to analysis. It is advisable to keep the indigo 
 solution gently heated while the test liquor is being added : 
 it is also necessary to stir the liquor well after each 
 O 
 
I 9 4 DYEIXG AND CALICO PRINTING. 
 
 addition of the standard solution, and towards the end of 
 the operation to add only a small quantity of the latter at 
 a time. The characteristic change of colour which the 
 mixture undergoes will distinctly indicate the approach of 
 the process towards completion. 
 
 The great objection to these modes of determining the 
 amount of indigotin is, that the oxidising agent not only acts 
 on that compound, but also on the other colouring matters 
 described by Berzelius, and the figures obtained are con- 
 sequently always too high. In fact, whilst commercial 
 indigo usually contains only from 45 to 60 per cent, of 
 indigotin, these processes show from 70 to 80. 
 
 The following equation will explain the action which 
 
 takes place in the bichromate process. 
 
 3 C 8 H 3 XS0 4 4- 8HC1 + K 2 Cr 2 7 = 
 Sulphindigotic Hydrochloric Bichromate 
 acid. acid. of potash. 
 
 3 C 8 H,NOS0 4 + 4OH0 + 2HCI + Cr 2 Cl 3 . 
 Sulphisatic acid. Water. Chloride of Sesqui- 
 
 potassium. chloride of 
 chromium. 
 
 The third class is based on the partial oxidation of 
 indigotin. In this case an alkaline solution is employed 
 instead of an acid one as in the second class. 
 
 By the process devised by M. Clement Ullgren, 15 grains 
 of indigotin and of the indigo to be tested are each dis- 
 solved in 120 grains of concentrated sulphuric acid. These 
 solutions are made up to a quart with water. One hun- 
 dred and seventy-five grains of the liquid are diluted 
 to a quart with water, and to this solution carbonate 
 of soda is added, care being taken that there is not a 
 great excess of the alkali. Seventy-five grains of ferri- 
 cyanide of potassium are dissolved in a quart of water, 
 and a small quantity of caustic soda added. The ferricy- 
 anide solution is now very carefully added to the ready 
 prepared weak solutions of indigo, and of indigotin, and the 
 quantity required to convert the blue colour into a pale 
 
TESTING INDIGO. 195 
 
 yellowish tint, carefully noted. In this case the indigo 
 is oxidised at the expense of the ferricyanide, which is 
 reduced to ferrocyanide ; the completion of the operation 
 can therefore be accurately ascertained by testing for the 
 presence of ferricyanide from time to time. The propor- 
 tion between the quantity required to decolorise the 
 standard indigotin solution, and that of the indigo to be 
 tested, will give the percentage of indigotin in the latter. 
 This process is founded on the conversion of the indigotin 
 into isatin, as shown by the following formula : — 
 
 C 16 H 10 N. 2 O 2 + 2 K 3 FeCy + 2KHO = 2 C 8 H 5 N0 2 + 
 Indigotin. Potassium ferri- Potassium Isatin. 
 
 cyanide. hydrate. 
 
 2 K 4 FeCy 6 + OH 2 . 
 
 Potassium ferro- Water, 
 
 cyanide. 
 
 The fourth class is founded on the reduction of indigotin 
 to white indigo and the solution of this latter compound 
 in alkalis, by which it is separated from the impurities it 
 may contain, being afterwards reoxidised by exposure to 
 the atmosphere. 
 
 The first of these processes was devised by Fritzsche; 
 10 or 20 grains of indigo, dried at 2i2°F., are introduced 
 into a bottle containing an equal weight of grape sugar 
 and three times its weight of caustic soda dissolved in 
 forty parts of alcohol. The quantity of liquid must be 
 such as to quite fill the bottle employed to contain it. It 
 is kept in a warm place until the whole of the indigo is 
 dissolved. The pale yellow liquid is then decanted and 
 exposed to the atmosphere, when the white indigo absorbs 
 oxygen, and the indigotin is deposited often in the form of 
 beautiful prismatic crystals. Schunck has shown, however, 
 (p. 156), that this process may yield very incorrect results; 
 for it is possible that part or even the whole of the indi- 
 gotin may remain in solution, combined with alcohol and 
 acetic acid ; in this state it does not yield a precipitate of 
 indigotin by exposure to the atmosphere. 
 
1 96 DYEING AND CALICO PRINTING. 
 
 The second process, devised by the author, although 
 requiring longer time, has been found to give very satis- 
 factory results; by its means a very close approximation 
 is obtained to the amount of colour practically available. 
 Twenty or thirty grains of finely pulverised indigo are placed 
 in a flask, with twice its weight of ferrous sulphate, two hun- 
 dred of water, and six of caustic soda. The flask is closed 
 by a perforated cork, in which are fixed a small bent 
 tube, which can be connected with a jar of hydrogen, and 
 a syphon going almost to the bottom of the liquid, and 
 closed with a pinchcock. A gentle heat is applied for two 
 hours, after which, the heating is discontinued and the pre- 
 cipitate allowed to settle. The tube is then connected 
 with the jar of hydrogen, and the liquid run off. The 
 residue in the flask is treated again with half the above 
 quantities of iron salt and caustic alkali. The syphoned 
 liquor is placed in shallow vessels and well stirred. The 
 indigotin thus produced is collected, washed, dried, and 
 weighed. 
 
 Leuchs* has introduced a modification of the above pro- 
 cess in which the solution of white indigo, instead of being 
 exposed to the air, is acidulated with sulphuric acid, and 
 then oxidised by adding a solution of ammonia iron 
 alum, the reaction being as follows: — 
 
 C 16 H 12 N 2 2 + Fe 2 3 - C 16 H 10 N 2 O 2 + aFeO + OH 2 . 
 Indigo white. Indigotin. 
 
 The amount of ferrous salt produced by the deoxidation 
 of the ferric sulphate is ascertained in the usual way, by 
 means of a standard solution of potassium chromate. 
 The methods followed to obtain fast indigo blues are all 
 based on the principle of the reduction of blue indigo to 
 white indigo. The latter compound is held in solution by 
 an alkali, which enables the dyer or printer to introduce it 
 into the fibre of the cloth, where on exposure to the atmo- 
 
 *Zeit. Chem. [2] v. 159. 
 
COLD VAT. 
 
 197 
 
 sphere the alkali combines with carbonic acid, and the white 
 indigo thus liberated absorbs oxygen and becomes insolu- 
 ble blue indigo. As far as dyeing is concerned the pro- 
 cesses can be classed under two heads, hot and cold. The 
 hot process is principally applied to wool, the cold to vege- 
 table fibres, especially cotton. 
 
 The oldest and still most generally employed method of 
 preparing cold vats consists in putting into a vat containing 
 about 2,000 gallons of water, 60 lbs. of indigo, in very fine 
 powder, 180 lbs. of slacked lime, and 120 lbs. of ferrous 
 sulphate or green vitriol (free from any trace of copper salt), 
 the two last-named substances being added from time to 
 time. The greater part of the lime employed unites with 
 the sulphuric acid of the iron salt to produce sulphate of 
 lime or gypsum, and the liberated protoxide of iron 
 removes the oxygen from the indigo, becoming converted 
 into ferric oxide, whilst the reduced indigo dissolves in the 
 excess of lime employed. It is always advisable to take 
 the precaution of adding the lime first, and to stir the con- 
 tents of the vat before adding the copperas, so that there 
 may be excess of lime present to dissolve the indigo as it 
 is reduced. On the other hand, care must be taken that 
 the total amount of lime employed shall not be in great 
 excess, for, as already stated, white indigo forms two com- 
 pounds with lime, one of which is soluble and the other 
 insoluble ; if the latter were formed, it would of course not 
 be available for the purposes of dyeing. 
 
 This is not, however, the most serious loss of indigo in 
 the blue-dip vats, the chief being the combination of indi- 
 gotin with the protoxide of iron, forming a green bulky 
 floculent precipitate, which, together with the sulphate of 
 lime, is a great source of annoyance to the dyer, increasing 
 the difficulty of obtaining uniformly dyed surfaces. 
 
 Many years ago, the author devised the following simple 
 process for recovering the waste indigo: — It consists in 
 
198 DYEING AND CALICO PRINTING. 
 
 syphoning off the clear liquor which remains in the ex- 
 hausted or spent vat, and pumping up into a tank the 
 green pulpy mass above referred to, leaving at the bottom 
 of the vat the bulk of the lime and other impurities which 
 may be present. To the pulp in the tank, dilute hydro- 
 chloric acid is added to dissolve any carbonate of lime or 
 caustic lime that may be present, and about 10 per cent, of 
 strong hydrochloric acid is then added to decompose the 
 indigotate of lime; the whole being left to settle for twelve 
 hours. The clear liquor is then syphoned off, and a quan- 
 tity of hydrochloric acid added to the residue until it is 
 strongly acid. By this means the iron compound is 
 decomposed, chloride of iron being produced and white 
 indigo liberated, which rapidly becomes converted into 
 indigotin. After being collected and washed it is ready for 
 use. From 10 to 15 per cent, of indigo is thus recovered. A 
 printer or dyer adopting this method of treating his spent 
 vats can render all the indigotin of the indigo employed 
 available for dyeing, within about 2 or 3 per cent. 
 
 It is most important that the indigo used in this and the 
 following dyeing processes should be very finely pulverised 
 in order to facilitate its reduction. Several forms of appa- 
 ratus are in use for this purpose, but the one most generally 
 employed consists of a vat in which are a pair of mill- 
 stones, the lower one of which is fixed and the upper one 
 revolves, being driven by means of a lantern wheel. At the 
 bottom of the trough is a tap, by means of which the con- 
 tents of the vat may be drawn off into a bucket. The 
 indigo is ground with water between the stones, and when 
 it has attained the consistence of cream it is drawn off by 
 the tap into a sieve placed on the bucket. Any portion of 
 the indigo not sufficiently ground is thus retained and put 
 back in the mill. 
 
 Messrs. R. Schloesser and Co., of Manchester, have 
 introduced, within the last year or two, a marked improve- 
 
COLD VAT. 
 
 199 
 
 ment in the preparation of cold vats, the invention of 
 which appears to be due to MM. Cohen Freres, of Rouen, 
 and patented by them September 4th, 1867. This pro- 
 cess removes the great objections of the bulky precipitate of 
 sulphate of lime, the formation of an oxide of iron, and 
 the loss of indigo by its combination with the oxide of 
 iron just referred to; moreover, as the bath remains much 
 more fluid, the pieces are less apt to be spotted, and a 
 better class of work is produced. The amount of bottoms is 
 only about one-seventh of the bulk of that produced when 
 copperas is employed, consequently the vats can be used a 
 much longer time than in the old process, and there is a 
 saving of time and of indigo. To carry out their process 
 they add to the ordinary 2,000 gallon vat 20 lbs. of ground 
 indigo, 30 lbs. of iron borings, 30 lbs. of powdered zinc, 
 and 35 lbs. of quicklime; the whole is stirred up from time 
 to time for twenty-four hours, when it is ready for use. If 
 the bath is not considered sufficiently strong, a little more 
 lime and zinc are introduced. 
 
 The chemical theory of the process is that zinc, in the 
 presence of lime, takes up oxygen from the water, and the 
 liberated hydrogen then converts the indigotin into white 
 indigo, which is dissolved by the excess of lime. In the 
 working of these vats, two difficulties may present them- 
 selves; first, the formation of a large quantity of froth 
 on the surface of the liquid; and, secondly, a turbid 
 appearance. Both these effects are due to the presence of 
 an excess of reducing material in the water, and may be 
 easily remedied by stirring up the vat quickly from time to 
 time; this liberates the hydrogen from the frothy mass, 
 and brings up the indigo from the bottom to be acted on 
 by the other agents. The stirring facilitates the clearing of 
 the vat, and renders it soon ready for use. 
 
 To dye cotton yarn in these vats, it is simply necessary 
 to dip it for a few minutes in the dye bath and expose it to 
 
200 DYEING AND CALICO PRINTING. 
 
 the atmosphere, when the green hue it has acquired passes 
 rapidly into blue. This operation is repeated until the 
 yarn has attained the required depth of shade, when it is 
 passed through dilute sulphuric acid, and after being 
 washed is ready for the market. 
 
 To dye calicos the pieces hooked on frames are passed 
 through a bath of weak milk of lime, and then dipped into 
 the reduced indigo vat. After fifteen minutes immersion, 
 the frame is taken out and the cloth exposed to the air for 
 about the same length of time. It is then dipped again, 
 the process being repeated until the required depth of tint 
 is attained. It is finally passed through dilute sulphuric 
 acid and washed. The cold vats are especially used when 
 it is wished to obtain white and yellow designs upon a blue 
 ground. There are two distinct processes by which the 
 whites are produced, one by employing substances to pre- 
 vent the fixing of the indigo on those places, which is 
 called a 'resist' process; the other, by removing the indigo 
 from them by means of oxidising agents, which is called 
 a 'discharge' process. 
 
 To carry out the resist or reserve process I lb. of nitrate 
 and 3 lbs. of sulphate of copper are dissolved in a gallon 
 of water. To this are added 4 lbs. of pipeclay, 1 lb. of 
 flour, and 1 lb. of flummery (the refuse product from 
 wheaten starch manufactures). The paste so prepared is 
 printed on those parts of the piece which it is intended 
 should remain white, after which they are hung up in a 
 room for two or three days, according to the style of goods. 
 The pieces are then hooked on to the frames and dipped 
 in the vat, when the indigotin fixes itself on the non- 
 printed parts of the fabric, but will not colour the part 
 where the resist is printed, partly owing to the mechanical 
 resistance of the pipeclay and the insoluble nature of the 
 paste employed, but chiefly to the oxygen of the salts of 
 copper oxidising the indigo before it can penetrate the 
 
DISCHARGE PROCESS. 201 
 
 fibre, thus rendering it incapable of fixing itself on the 
 fabric. We are indebted to the kindness of Messrs. Wood 
 and Wright for the two following patterns, illustrating the 
 resist process and the discharge process respectively. 
 
 RESIST PROCESS. 
 
 The discharge process, first applied by Mr. John Mercer, 
 of Accrington, is carried out as follows: — The cloth, after 
 being dyed with indigo in the usual manner, is padded 
 with a solution of bichromate of potash, containing about 
 8 oz. of salt to a gallon of water. This operation and 
 the subsequent drying are performed in a dim light, as 
 exposure to a strong light would impair the beauty of the 
 blue, and mighf even injure the fibre of the cloth. The 
 fabric is now printed with a discharge, containing oxalic, 
 tartaric, citric, and sometimes hydrochloric acid. For 
 roller printing, however, Persoz gives the following pro- 
 cess: — In two-thirds of a gallon of water dissolve 2 lbs. of 
 oxalic acid; to the remaining third, add 7^2 lbs. of 
 calcined farina, 12]4 lbs. of sulphate of lead, and 1*28 lbs. 
 of sulphuric acid; then mix the whole. When the cloth 
 has been printed with this discharge it is immediately 
 rinsed in water, containing some chalk in suspension; 
 
202 
 
 DYEING AND CALICO PRINTING. 
 
 then rinsed at the dashwheel, passed through dilute sul- 
 phuric acid, and lastly washed in clean water. 
 
 RESIST AND DISCHARGE. 
 
 When the object in view is to produce a self-colour, a 
 much more rapid process is adopted. Pieces of calico, 
 from which all the sizing material has been removed, are 
 made to pass over a series of rollers a,b,c,d, in the vat, A, 
 
 i* ; i ; ^>~Si^^\^^-$SSS^^ 
 
 Fig. io. 
 
 Fig. 10, containing reduced indigo, copperas, and caustic 
 soda, which is maintained at a temperature of 150 F. ; then 
 through the rollers e into another vat, B, containing dilute 
 sulphuric acid, which neutralises the alkali and throws 
 
INDIAN VAT. 203 
 
 down the white indigo upon the fabric. They are next 
 carried forward through another pair of rollers, f, into a 
 third vat, which must be freely supplied with a current 
 of water; this not only rapidly oxidises the indigo, 
 but removes the sulphate of soda which has been pro- 
 duced. When dried and stiffened the pieces are ready for 
 market. 
 
 There is still another process, which is now used only to 
 a limited extent, but was at one time very extensively 
 employed. It produces on the cloth a pale blue, which 
 has a great similarity of tint to that seen on china or 
 porcelain, and from which circumstance it derives its name 
 of china-blue. To produce it, the pieces are printed with 
 a mixture containing very finely powdered indigo and a 
 little acetate of iron, and are made to pass through six 
 successive vats. The first two contain lime; the third, 
 sulphate of iron; the fourth, a solution of caustic soda; 
 the fifth, a dilute solution of sulphuric acid ; and the sixth, 
 water. When the design has acquired the required depth 
 of blue the pieces are washed, passed once more through 
 weak sulphuric acid, and again washed. The chemical 
 reactions are exactly similar to those in the cold vat pro- 
 cess, except that instead of the indigo being in solution it 
 is reduced on the surface of the fabric, and is absorbed by 
 the fibre as quickly as it is rendered soluble. 
 
 For dyeing wool, a modification of the old woad vat is 
 employed, but the use of woad being now almost entirely 
 discontinued, indigo has been substituted for woad. It 
 bears the name of the Indian vat, doubtless from the pro- 
 cess having been practised in India and imported from 
 thence. It is as follows: — 8 lbs. of powdered indigo is 
 added to a bath containing 3^ lbs. of bran, 3^ lbs. of 
 madder, and 12 lbs. of potash, which is maintained for 
 several hours at a temperature of 200 F. It is then 
 allowed to cool to ioo° F., when fermentation ensues. 
 
204 DYEING AND CALICO PRINTING. 
 
 After about forty-eight hours the indigo is rendered solu- 
 ble, being reduced by the decomposition, during the process 
 of fermentation, of the sugar and other products contained 
 in the bran and the madder root. The bath should have 
 a greenish-yellow appearance, and a frothy scum of a 
 blue coppery hue 
 
 Of late years, improvements have been made in this 
 class of vats, by which the expense of using madder is 
 avoided. They are now prepared by adding to water, at a 
 temperature of 200° F., 20 buckets of bran, 26 lbs. of soda 
 crystals, 12 lbs. of indigo, and 5 lbs. of slacked lime. 
 After five hours the bath is allowed to cool to ioo° F., 
 when fermentation ensues and the indigo is dissolved in 
 the alkali. The management of these vats requires great 
 experience and care, for if the fermentation is too slow 
 the indigo is not properly reduced, whilst if too active 
 large quantities of indigo may be lost. The researches of 
 Schunck, already referred to, not only show the method 
 of avoiding this loss, but explain why it occurs. The 
 remarks previously made as to the causes of failure in 
 the manufacture of indigo are applicable here, namely, 
 that if the fermentation becomes alcoholic and acetic, the 
 non-oxidisable indigo compounds described by Schunck 
 are generated. 
 
 While noticing the reduction of indigo by means of 
 organic substances, a process may be described which has 
 been introduced by M. Leuchs,* of Neuremberg. He 
 employs a new class of reducing agents, namely, pectose, 
 pectin, and pectic acid, which are furnished in abundance 
 by apples, pears, gooseberries, and other fruits; by melons 
 and other cucurbitaccce ; but in the largest quantities and at 
 the lowest cost in carrots and turnips. The following is 
 the method he adopts: — Two hundred pounds of soda ley, 
 of specific gravity 1 "35, are heated to a temperature of 
 
 *Tech., xxvii., 128. 
 
LEU CHS' VAT. 205 
 
 170 R, and 2 lbs. of indigo pulp added. In this alkaline 
 liquor an iron cage is suspended,, containing 30 to 40 lbs. 
 of chopped turnips, and the whole raised to the boiling 
 heat. The insoluble pectose of the turnip is thus con- 
 verted into pectic acid, which is soluble, and the indigo 
 is reduced and dissolved. It is advisable to exclude the 
 air from the boiler as much as possible. When cold, this 
 liquor is added to 42 gallons of water, and is ready for use 
 by the dyer. The inventor considers that his process is 
 more advantageous than the old ones, both for cheapness 
 and convenience. It only requires 9 lbs. of turnips to 
 reduce one of indigo, while all the loss of indigo which 
 occurs in the copperas process is avoided, and the deposit, 
 which is often such a source of annoyance, does not take ■ 
 place. The comparatively short time necessary is a great 
 advantage as compared with the fermentation process, and 
 the goods dyed with it do not require to be passed through 
 an acid bath to fix the indigo and give it brilliancy. 
 
 It is a curious fact that indigo is occasionally produced 
 in the human system. Medical men had observed from 
 time to time that urine, secreted under certain pathological 
 conditions, became brown, and sometimes even blue, when 
 exposed to the atmosphere. Hassel discovered that in 
 some instances the colouring matter was indigo, but 
 here again we are indebted to Schunck for much infor- 
 mation on the subject. In three papers presented to the 
 Royal Society, he has proved that urine, in cases similar to 
 those examined by Hassel, contained indican. He also 
 observed that indican was a very frequent constituent 
 of urine secreted by persons in a healthy state, and in fact 
 that it is produced generally when persons do not take 
 sufficient exercise; and he has on several occasions suc- 
 ceeded in producing it by taking in his food a rather large 
 excess of sugar. 
 
CHAPTER VII. 
 
 COCHINEAL, KERMES, GUM-LAC, LAC-DYE, LAC-LAKE, AND 
 MUREXIDE. 
 
 Cochineal, Kermes, and Lac-dye. — These colouring 
 matters are obtained from the animal kingdom, being 
 derived from three distinct species of a peculiar tribe of 
 insects called Coccina. 
 
 The real cochineal, Coccus cacti, lives and propagates on 
 certain varieties of cactus which grow in Mexico, the nopal 
 principally. Kermes, Coccus ilicis, is found on a species of 
 oak named the Ilex, or Quercus coccifera, which grows in 
 Spain, the south of France, Italy, and the islands of the 
 Grecian Archipelago, especially Candia. Poland kermes, 
 Coccus polonicus radicals, lives on the roots of the Sclerauthus 
 of Poland, and the Russian kermes, Coccus uvaursi is found 
 in the Ukraine. Lac-dye is prepared from lac, a product 
 derived from the Coccus lacca, or ficus, which is found in 
 large quantities on the banyan, the juniper, and other trees 
 in India. 
 
 The dyes obtained from some species of these insects, 
 were well known to the ancients, and were much used in 
 Persia and India; and although there is no doubt that the 
 Romans were acquainted both with kermes and lac-dye, 
 yet their use seems to have been discontinued in Europe 
 after the fall of that Empire, since no mention is made of 
 it by Giovanni Ventura Rosetti, who, in the year 1429, pub- 
 lished the earliest work on dyeing at Venice. On the con- 
 quest of Mexico by the Spaniards, they found this dye in 
 
COCHINEAL. 207 
 
 use among the natives, who had -employed it for many- 
 centuries. It was shortly afterwards introduced into 
 Europe, probably in the year 15 18, and owing to the 
 brilliancy and fastness of the colour it soon came into 
 great demand, as would appear from the fact that in 1581 
 the quantity imported into Spain was 150,000 lbs. From 
 that time this dyestuff was still more largely employed, 
 owing to the discovery of the splendid scarlet which it pro- 
 duces on wool when salts of tin are added to the dye bath. 
 In 1830 it was propagated in the Canary Islands, the 
 island of Teneriffe, Java, and Algiers, and large quantities 
 are now exported from those countries. The best qualities 
 are still obtained from the republic of Honduras. 
 
 Cochineal. — The cochineal insect belongs to the tribe 
 Coccina, several species of which are found in our own 
 country, and these 'bugs' are well known to our gardeners 
 from the injury they do to many plants, especially in hot- 
 houses. 
 
 Nothing can be more dissimilar in appearance than the 
 two sexes of these singular insects. The female, from 
 which alone the colour is obtained, forms a mere fleshy masi- 
 almost destitute of limbs, remaining attached to one spot 
 on the plant on which it is produced, and from which it 
 continues to derive its nutriment until it attains its full 
 size. The males, on the contrary, are elegant creatures, 
 furnished with a single pair of filmy wings, whilst from the 
 abdomen there grows a pair of long filaments. As already 
 stated it principally lives on a species of cactus called the 
 'nopal,' or Cactus opuntia, or Cactus cocciuilifera. This 
 plant is indigenous to Mexico, where it grows in the wild 
 state; and from which large quantities of cochineal are 
 collected. It is also extensively cultivated by the native 
 Indians, who often have gardens, or nopaleries containing 
 60,000 plants. The cochineal obtained from the two 
 sources is of different quality; that from the cultivated plant 
 
208 DYEING AND CALICO PRINTING. 
 
 is much superior, and - is called mesteque, or grana fina; 
 that collected from the wild plant being called sylvestra. 
 
 The following is a brief account of the manner in which 
 cochineal is cultivated and prepared for market. In the 
 month of May in the fiat lands, and in November in the 
 mountainous districts, the Indians take the stems of the 
 cactus, which they have preserved from a previous crop, 
 and remove from them the young female insects, which 
 are placed on the growing plants, where they multiply 
 with great rapidity. After a period of about three 
 months, the insects are collected in small straw baskets 
 or tin dishes, so formed as to enclose the bottom part 
 of the plant, being swept into it from each stem suc- 
 cessively by means of a small brush. They are then 
 destroyed, either by being thrown into hot water, and 
 afterwards dried in the sun or in stoves, which gives 
 the black cochineal, called zacatilla ; or they are placed 
 in a bag and stoved at once, which leaves upon them 
 that peculiar lustrous appearance which characterises the 
 silver-white cochineal called bianco. There is often a 
 second production of cochineal before the wet season sets 
 in ; if so, it is scraped off with a knife and dried, but it is of 
 inferior quality, and is sold under the name of granilla. 
 
 Although a pound of cochineal contains 70,000 insects, 
 an acre of nopal produces about 300 lbs. of cochineal, and 
 there are millions of pounds imported into Europe every 
 year. 
 
 If one of the dried insects be placed in warm water for 
 fifteen hours, it swells and takes a hemispherical form, 
 when its structure can be seen. It will be found to be 
 covered with rings, and to be furnished with feet and a 
 rostrum. If the animal is pressed between the fingers 
 thousands of little red granules are exuded, which when 
 placed under the microscope are seen to be the eggs of the 
 insect. 
 
CARMINIC ACID. 209 
 
 Cochineal has been the subject of several chemical 
 investigations. It was examined by John in 181 3, who 
 gives the following as the results of his analysis : — 
 Colouring principle, semi-solid, soluble in water 
 
 and alcohol 50*0 
 
 Gelatin 10*5 
 
 Waxy fat io - o 
 
 Modified mucus 14-0 
 
 Membrane 14*0 
 
 Alkaline phosphates, and chlorides, and phos- 
 phates of lime, iron, and ammonia 1*5 
 
 IOO'O 
 
 The colouring principle was first carefully examined by 
 Pelletier and Caventou in 18 18, who considered it to be an 
 azotised compound. In order to extract the colouring 
 matter they first removed the fatty bodies by means of 
 ether, and then dissolved out the colouring matter by boil- 
 ing alcohol. On cooling, a red deposit was formed, which 
 was redissolved in alcohol, and the solution shaken up with 
 ether ; a precipitate was thus thrown down, which was the 
 carmine of these chemists, and to which they assigned the 
 
 formula, 
 
 C 1(; H 2 ,N,O 10 . 
 
 Arppe and Warren de la Rue, however, again investi- 
 gated the subject in 1847, and cam 2 to the conclusion that 
 the colouring matter did not contain nitrogen, although it 
 is accompanied by nitrogenous matter, from which it is very 
 difficult to separate it. They found that it possessed acid 
 properties, and therefore gave it the name of carminic acid. 
 From the results of their analysis they believed it to have 
 the formula C u H u O s . 
 
 Schiitzenberger considers that the carmine of Pelletier 
 and Caventou is a compound of carminic acid, and an 
 organic azotised base called tyrosine. 
 
 The process devised by Arppe and Warren de la Rue has 
 P 
 
210 DYEING AND CALICO PRINTING. 
 
 b^en slightly modified by Schiitzenberger, who succeeded 
 in obtaining the acid in the crystalline form. Cochineal in 
 grains is washed with ether to remove the fatty matters, 
 and then treated several times with boiling water. The 
 addition to the red liquid of a solution of acetate of lead, 
 rendered slightly acid by means of acetic acid, causes a 
 violet-blue precipitate, which contains all the colouring 
 matter ; the supernatant liquid being either colourless, or 
 of a faint yellowish tinge. After being thoroughly washed 
 with warm water, the precipitate consists principally of 
 carminate of lead and phosphate of lead, together with a 
 very small quantity of nitrogenous compounds ; by far the 
 greater portion of the latter is removed by the washing, and 
 the filtrate on concentration yields small needles of tyrosine, 
 other organic matters remaining in solution in the syrupy 
 liquid. 
 
 The lead precipitate is suspended in warm water, and a 
 quantity of sulphuric acid added barely sufficient to decom- 
 pose the carminate, leaving the phosphate unattacked. 
 The carminic acid thus liberated is dissolved in water, and 
 the solution evaporated to dryness in a water bath at a 
 temperature not exceeding 120 F. The residue is dis- 
 solved in absolute alcohol, which on evaporation and cool- 
 ing, yields the carminic acid in the crystalline state. In 
 order to free it from a small quantity of yellow colouring 
 substance, it is dissolved in water, filtered, and evaporated. 
 The residue is then recrystallised from ether, or from abso- 
 lute alcohol. 
 
 According to Schiitzenberger the formula of carminic 
 acid is C 3 H 8 0j, whilst Schaller makes it C 9 H 8 6 . 
 Hlasiwetz and Grabowski* published 'a paper in which 
 they state that carminic acid yields definite compounds 
 with potassium and barium, from an examination of which 
 they find the true formula of carminic acid to be Ci 7 H 18 O 10 . 
 
 * Ann. Chem. Tharm., cxli., 129. 
 
CARMINE RED. 2 1 1 
 
 When boiled with dilute acids it splits up, yielding sugar 
 and a new substance, carmine red. 
 
 C^Ao + 2OH, = C n H 12 7 + C 6 H ia 5 . 
 
 Carminic acid. Carmine red. Sugar. 
 
 This unfolding of carminic acid into carmine red and 
 sugar is very interesting, as it shows that some animal 
 colouring matters are formed according to the same law as 
 those of the vegetable kingdom, and like them are glucor 
 sides. It is not improbable that the tyrosine found in the 
 solutions of cochineal is the product of the decomposition 
 of a peculiar ferment which exists in the insect, but which 
 is destroyed in the stoving, or steeping in boiling water, to 
 which it is subjected in its preparation for the market 
 
 To prepare carmine red, these chemists throw down the 
 colouring matter from a decoction of cochineal in boiling 
 water, by acetate of lead, wash the precipitate carefully, 
 and then decompose the lead compound by dilute sulphuric 
 acid. The dark red solution thus obtained is filtered from 
 the sulphate of lead, and sulphuretted hydrogen is passed 
 through it to precipitate the last traces of lead. The 
 liquid, after being again filtered, is boiled with a little dilute 
 sulphuric acid to decompose the carminic acid, then 
 neutralised by carbonate of baryta, filtered from the 
 barium sulphate, and the colouring matter thrown down 
 by acetate of lead. The precipitate is decomposed by 
 dilute hydrochloric acid, the coloured liquid is filtered, and 
 sulphuretted hydrogen passed through it to precipitate the 
 lead remaining in solution, after which it is evaporated at 
 a gentle heat. The residue is again treated with cold 
 water, which leaves undissolved some resinous floculent 
 matter and the solution evaporated in vacuo over sulphuric 
 acid. A brilliant purple-red mass is thus obtained, which 
 appears green by reflected light, and when powdered has a 
 dark cinnabar red colour. It is insoluble in ether, but 
 gives beautiful red solutions with water and alcohol. 
 
212 DYEING AND CALICO PRINTING. 
 
 By fusing carminic acid with caustic potash, these chemists 
 obtained a yellow crystalline substance to which they gave 
 the name coccinin, CuHuOg. This substance is insoluble 
 in water, but soluble in alcohol and ether. It is very solu- 
 ble also in dilute alkalis, giving a yellow solution, which, in 
 contact with the air, becomes first green, then violet, and 
 finally reddish-purple. 
 
 Carminic acid is insoluble in ether, but soluble in water, 
 alcohol, bisulphide of carbon, and benzene. It is not 
 decomposed by a heat of 280° F., and may be dissolved 
 without decomposition in concentrated sulphuric or hydro- 
 chloric acid. When fixed on fabrics, especially on wool, 
 it is one of the fastest colours known, neither light nor air 
 having any action on it. Nascent hydrogen reduces it, 
 producing a colourless compound, but it is again converted 
 into the red carminic acid on exposure to the atmosphere. 
 Chlorine, bromine, and iodine, however, easily destroy it. 
 
 The general properties of the carminates have not been 
 much studied. Schiitzenberger has, however, obtained a 
 crystallised carminate of soda, to which he assigns the 
 formula, Na.,0, C 9 H 8 5 ; and Messrs. Hlasiwetz and Gra- 
 bornski have also prepared potassium and barium com- 
 pounds, having the formula C 17 H 10 K 2 O 10 + ^OH 2 , and 
 C 17 H 10 Ba O 10 respectively. The soda salt crystallises in 
 purple plates. 
 
 Guignet* has recently obtained a lime salt which he 
 prepares by mixing a solution of carminic acid with a salt 
 of lime, the best for this purpose being the bicarbonate. It 
 falls as a black precipitate, which is insoluble in water and 
 alcohol. Concentrated acetic acid dissolves it completely, 
 the solution being of a bright red colour, but on evapora- 
 tion, the black salt is deposited unchanged. He considers 
 it to be a neutral carminate, but has not analysed it. 
 
 Carminic acid gives with caustic alkalis a beautiful red 
 
 * Bull. Soc. Chim. [2] xviii., 162. 
 
REACTIONS OF COCHINEAL. 213 
 
 colour; with baryta and lime waters, a purple precipitate; 
 with salts of barium, and with acetates of lead and copper, 
 purple precipitates; with tin bichloride, a red precipitate; 
 and with cream of tartar, or potassium oxalate, an orange- 
 red precipitate. Alumina removes the whole of the colour- 
 ing matter from an aqueous solution, yielding a beautiful 
 red lake, which on being heated, becomes first crimson, 
 then purple. The addition to the lake of a little acid, or 
 acetate of alumina, produces the same result. 
 
 Warren de la Rue found that by acting on carminic acid 
 with nitric acid of specific gravity 1*4, he obtained a new 
 acid which he called nitrococcusic acid, nitrous fumes 
 being given off, and oxalic acid being formed at the same 
 time, the latter no doubt being the product of the decom- 
 position of the sugar already spoken of. The formula of 
 nitrococcusic acid is C 8 H 5 (NOo)a0 3 + OH 2 . It crystal- 
 lises in fine yellow scales. 
 
 Liebermann and Van Dorp confirm these results. They 
 have also obtained a body somewhat similar to coccinin 
 which they call ruficoccin, by heating carmine in concen- 
 trated sulphuric acid to a temperature of 300 F. 
 
 A decoction of cochineal acts rather differently with 
 reagents from a solution of carminic acid, owing to the 
 phosphates and tyrosine which it contains. 
 
 The following are its characters : — 
 
 c Change the colour to a yel- 
 
 Acids. -I lowish-red, causing a slight 
 
 ^ precipitate. 
 
 Alkalis. Change it to violet. 
 
 Lime water. Violet precipitate. 
 
 . , C Changes its colour to red, then 
 
 Alum. . 
 
 (. causes a precipitate. 
 
 {Reddish-violet precipitate, the 
 supernatant liquor becom- 
 ing- crimson. 
 
214 DYEING AND CALICO PRINTING. 
 
 { 
 
 ( Colour changes to yellow, and 
 Acid chloride of tin. -I a cherry-coloured precipi- 
 
 tate falls. 
 
 Neutral chloride of tin. Violet precipitate. 
 
 Bichloride of tin. Bright scarlet coloration. 
 
 _ , , ( Violet -grey coloration and 
 
 Ferrous sulphate. < . . 
 
 (. precipitate. 
 
 ... ( Brown precipitate, which 
 
 Acetate of iron. < , \. 
 
 I changes to olive-green. 
 
 Sulphate of copper. Violet precipitate. 
 
 Salts of lead. Violet precipitate. 
 
 Mercurous acetate. Wine-red precipitate. 
 
 Mercuric acetate. Reddish-brown precipitate. 
 
 Sulphate of zinc. Dark violet precipitate. 
 
 Cream of tartar. Red precipitate. 
 
 Oxalic acid. Red precipitate. 
 
 As cochineal is an expensive dyestufif, it is liable to be 
 adulterated. One of the most common frauds is practised 
 at Nismes, and other places where perfumery is prepared. 
 The cochineal is put into water for a short time, by which 
 a part of the colour is extracted ; it is then dried, and 
 either sold as black cochineal, or placed in a sack and 
 shaken with talc or sulphate of lead, and sold as white 
 cochineal. The latter is easily detected by grinding the 
 cochineal and mixing it with water, when the talc or sul- 
 phate of lead falls to the bottom. Good cochineal does 
 not leave above 5 or 6 per cent, of ash. 
 
 It is often advisable before buying cochineal to deter- 
 mine its value by ascertaining its comparative tinctorial 
 power, and since it is difficult to prepare carminic acid, the 
 colouring principle of the cochineal, a sample of known 
 good quality must be obtained with which to compare the 
 sample to be tested. 
 
 The methods employed are various, but are all based on 
 three principles; the first on a comparison of the depth of 
 
TESTING COCHINEAL. 215 
 
 colour of the sample to be tested with that of a similar 
 solution of the standard, the second on the amount of 
 oxidising agent required to destroy the colours in the res- 
 pective solutions, and the third on their actual dyeing 
 power on equal surfaces of flannel. 
 
 In the methods based on a comparison of the strength 
 of colour of the solutions, the colouring matter of the 
 cochineal is extracted by boiling about 15 grains of it in 
 a quart of water, to which is added twenty drops of a 
 saturated solution of alum. After boiling for an hour the 
 liquors are allowed to cool and made up to the original 
 quantity, when they are ready for testing in an apparatus 
 called a colorometer. As, however, several of these have 
 been devised of late years, and the process is equally appli- 
 cable to many other colours, it has been thought better to 
 leave its description until treating of the general question 
 of the analysis and examination of colouring matters and 
 coloured fabrics. 
 
 Among the processes based on the destructive oxidation 
 of the colouring matter, may be mentioned that proposed 
 by Robiquet, who used a standard solution of bleaching 
 powder, and that lately published by Merrick, who employs 
 a dilute standard solution of permanganate of potash. 
 The best, however, of these processes is that adopted by 
 Penny. Twenty grains of cochineal are treated with about 
 1,000 grains of a dilute potash solution, and this is further 
 diluted with 2,000 grains of water. A solution of red 
 prussiate of potash is then prepared, containing one part 
 of the salt to two hundred of water, and this liquid is added 
 drop by drop from a burette to the cochineal solution 
 until the purple colour is removed, and the liquor has a 
 dull reddish-brown tinge. By a comparison of the quantity 
 of ferricyanide required for the oxidation of the standard 
 cochineal, and that requisite for the sample to be tested, the 
 relative value of the latter is determined. 
 
216 DYEING AND CALICO PRINTING. 
 
 All these processes, however, are objectionable, as there 
 are in cochineal other organic matters besides carminic 
 acid, which may be oxidised by the reagents employed and 
 thus lead to incorrect results. 
 
 To carry out the third principle of testing, which practi- 
 cally is the only thoroughly trustworthy one, the following 
 proportions will be found to give good results : — 
 
 For scarlet tints a bath is made composed of — 
 
 Water i quart. 
 
 Cream of tartar 32 grains. 
 
 Oxymuriate of tin 32 grains. 
 
 Cochineal, finely ground 16 grains. 
 
 For crimson tints — 
 
 Water 1 quart. 
 
 Cream of tartar 12 grains. 
 
 Alum 24 grains. 
 
 Cochineal 16 grains. 
 
 A piece of flannel weighing 100 grains is then placed in 
 the bath and dyed up to a full tone ; when this has been 
 done, a second piece is put in the bath and allowed to re- 
 main until all the colouring matter is exhausted. It is, 
 perhaps, necessary to remark here, that whenever any 
 comparative dyeing experiments are to be made, they 
 ought to be done in the same water bath, so as to be 
 exposed to exactly the same circumstances. If the cochi- 
 neal to be tested was pure, or merely had part of its colour 
 removed, this dyeing test would give its comparative value, 
 but as occasionally it has been found that cochineal has 
 been adulterated with the colouring matter of Brazil wood, 
 a further test is necessary before its purity can be affirmed. 
 To a solution of the cochineal, lime water in excess is 
 added, when, if pure, all the colouring matter will be thrown 
 down, whilst if any brasilin be present the liquid will have 
 a purple colour. 
 
 The chief employment of cochineal is for dyeing silk 
 
DYEING WITH COCHINEAL. 
 
 217 
 
 and wool by processes similar to that just described for 
 testing cochineal, but unfortunately the brilliant colours so 
 produced are affected by alkalis and soap, which impart to 
 them a purple hue. It is used in calico printing to pro- 
 duce pinks and reds in steam styles. The accompanying 
 sample of cochineal pink has been supplied by Messrs. 
 Wood and Wright. 
 
 COCHINEAL PINK, STEAM STYLE. 
 
 Woollen goods may be dyed, and cotton and silk goods 
 printed also in purple and mauve colours, with a peculiar 
 compound of the colouring matter of cochineal with am- 
 monia, known in the trade as ammoniacal cochineal. This 
 sample has been supplied by Messrs. Z. Heys and Sons, of 
 Barrhead, near Glasgow. 
 
 AMMONIACAL COCHINEAL. 
 
218 DYEING AND CALICO PRINTING. 
 
 AMMONIACAL Cochineal. — When one part of ground 
 cochineal is left in contact with three parts of ammonia for 
 several weeks, a chemical action ensues between the car- 
 minic acid and the ammonia, the latter losing hydrogen 
 and the former oxygen, so that water is eliminated and 
 an amide is formed, called carminamide. According to 
 Schiitzenberger, the change may be thus represented : — 
 
 C 9 H 8 5 + NH 3 = OH 2 + C 9 H 9 N0 4 . 
 
 Carminic Ammonia. Water. Carminamide. 
 acid. 
 
 A solution of carminamide does not give a scarlet pre- 
 cipitate with oxymuriate of tin, like carminic acid, but a 
 beautiful purple one. And the crimson, purple, and mauve 
 colours which it yields, as already stated, are not affected 
 by acids. 
 
 There are two commercial preparations of ammoniacal 
 cochineal — one in the state of a thick paste, the other as 
 small flat tablets. The first is prepared by mixing one 
 part of finely powdered cochineal with five or six parts of 
 ammonia : it is left to stand for two or three weeks, and 
 then heated until about two-thirds of the ammonia has 
 been driven off, when it is ready for use. 
 
 The second preparation is obtained by adding three 
 parts of ammonia to one of cochineal, in a closed vessel, 
 and leaving them to macerate for a month. After this 
 time, 40 per cent, of alumina in a gelatinous state is added 
 to the mixture, and the whole is then heated in a tinned 
 copper pan until the odour of ammonia can no longer be 
 perceived. The mass when cold should have sufficient con- 
 sistency to be moulded into cakes. 
 
 Carmine Lakes. — These very beautiful pigments are 
 prepared from a decoction of cochineal, and not from car- 
 minic acid, the animal matter which the insect contains 
 appearing to be essential to their production. Their dis- 
 covery was made accidentally by a Franciscan monk, at 
 Pisa. He had made an extract of cochineal with bitartrate 
 
PREPARATION OF CARMINE. 219 
 
 of potash for medicinal purposes; and one day, putting 
 some acid to the solution, found to his surprise that he 
 had a magnificent red precipitate of carmine. Homberg, 
 in 1656, knew how to obtain it. 
 
 Although the modes of preparing the finest qualities of 
 carmine are kept secret by the manufacturers, we know 
 that acid salts, such as bitartrate and binoxalate of potash 
 are usually employed, and the following process will give 
 very satisfactory results: — A pound of cochineal is heated 
 with 2 gallons of water, in which an ounce of alum has 
 been dissolved ; it is then raised to the boiling point, and 
 kept at that temperature for three minutes. After having 
 been allowed to settle for a short time, the clear liquid is 
 poured off and put aside for several days, when about an 
 ounce of a bright carmine lake is produced. Cream of 
 tartar may be substituted for the alum employed in this 
 process. 
 
 A second process consists in boiling, for two hours, 2 lbs. 
 of powdered cochineal in 15 gallons of water; 3 oz. of 
 pure nitrate of potash are then added, and the boiling 
 continued for three minutes, after which 4 oz. of binoxa- 
 late of potash are added, and the liquor again boiled for 
 ten minutes. It is next run off, and when it has become 
 clear, which takes place in about fifteen minutes, it is set 
 aside and allowed to stand for three weeks in shallow 
 glass vessels, when the carmine is deposited. The super- 
 natant liquor covered with fungus is carefully removed, 
 and the carmine collected and dried in the shade. 
 
 As these lakes are expensive, they are often adulterated 
 with starch, kaolin, vermilion, &c. The complete solu- 
 bility of pure carmine lakes in ammonia affords, however, 
 a ready means of detecting these adulterations. 
 
 Carmine is generally sold in the state of an impalpable 
 powder, or in small cakes wrapped in fine paper. Gela- 
 tinous and albuminous preparations are also made, and are 
 
220 D YEING AND CALICO PRINTING. 
 
 used by confectioners. Carmine is used principally by 
 artists, paper stainers, and fabric printers. 
 
 A lower quality of colour also occurs in commerce 
 called carmine lake or Florentine lake, which was manu- 
 factured at Florence for a long time. It is prepared by 
 mixing a weak alkaline solution of cochineal with a 
 solution of alum. 
 
 KERMES. — This colouring matter has received its name 
 from the Arabs, the word signifying little worm. It has 
 been known in the East from time immemorial, and 
 according to M. Girardin, Moses mentions it under the 
 name of jola. It was also used by both Greek and 
 Roman dyers, being mentioned by Pliny under the name 
 of coccigranum. He says that the natives of Hispania 
 paid half their tribute to the Romans with these grains, 
 which were employed for dyeing purple, and that those 
 produced in Sicily were the worst, whilst those from 
 Emerita, in Lusitania, were the best. 
 
 In Germany, from the ninth to the fourteenth century, 
 the serfs were bound to deliver to the convents, every year, 
 a certain quantity of kermes among the other products of 
 husbandry. It was collected from the trees on St. John's 
 day, between eleven o'clock and noon, with religious cere- 
 monies, and from this received the name of Johannisblut, 
 that is, St. John's blood. At that time a great deal of the 
 German kermes was sent to Venice, to produce the scarlet 
 to which that city give its name. 
 
 As already stated, kermes is derived from the Coccus 
 ilicis, found on the Ilex or Qitercus cocci/era, a shrub which 
 grows on arid rocky soils in hot climates, but which is not 
 specially cultivated for that purpose. 
 
 The young female animal fixes itself under the epidermis 
 of the leaves or young shoots of the oak in the early parts 
 of spring. As the insect grows it gradually swells out the 
 epidermis of the leaves or branches, with a multitude of 
 
KERMES. 221 
 
 excrescences somewhat similar to gall-nuts, having a bluish- 
 green hue, and covered with a white powder. During the 
 month of June, or just before the eggs produced would be 
 hatched, the animals are removed, and destroyed by 
 placing them for half an hour in the vapours of acetic acid 
 liberated from heated vinegar; they are then dried. This 
 process gives them the red appearance they usually present 
 when sent into the market as kermes. 
 
 When good, kermes is plump, of a deep red colour, 
 having an agreeable odour, and a rough, pungent taste. Its 
 tinctorial matter is soluble in water and alcohol ; it becomes 
 yellow or brownish with acids, and violet or crimson with 
 alkalis. Sulphate of iron blackens it, doubtless owing to 
 the presence of a small quantity of tannin derived from the 
 oak on which it lives. With alum it dyes blood-red ; with 
 salts of iron, a light purplish-grey; with salts of copper and 
 bitartrate of potash, an olive-green; with chloride of tin 
 and bitartrate of potash, a cinnamon-yellow. Scarlet and 
 crimson dyed with kermes were called grain colours. 
 
 Although this colouring matter is seldom used in 
 England, it is extensively employed in the South of 
 France, in Spain, Morocco, and Turkey, to dye Morocco 
 leather, and to give to woollen cloth that particular shade 
 which characterises the cap called 'fez' worn by the 
 Asiatics. 
 
 If the colour is not so brilliant as that of cochineal, it 
 has the advantage of not being changed by soap or dilute 
 alkalis, or by perspiration. It is also employed at Rome, 
 Florence, and Milan, to colour a very favourite beverage 
 known as 'alkermes.' 
 
 The colour-giving principle of this insect is apparently 
 identical with that of cochineal, but it requires twelve times 
 as much kermes as cochineal to produce a scarlet of the 
 same intensity with a salt of tin. 
 
 The kermes of Poland and Russia, which are used 
 
222 D YEING AND CALICO PRINTING. 
 
 exclusively in the countries in which they are found, are 
 employed in a similar manner to that above described. 
 
 Lac, Lac-DYE. — Gum-lac is the product of another 
 variety of Coccina, which lives especially on the Ficus religiosa 
 or banyan tree. It is a resinoid substance, the secretion of 
 which depends on the puncture of the insect, and is made 
 for the purpose of depositing its ova. Besides the banyan 
 tree, the Rhamnus jujuba, or juniper, the Croton lacciferum, 
 and the Butea frondosa which grows in Assam, Siam, Pegu, 
 Bengal, and Malabar, all yield this product. The animals 
 reproduce themselves with such rapidity, and in such 
 numbers, that they entirely cover the surface of the branches 
 of the trees on which they are deposited, forming solid 
 masses, which are often a quarter of an inch thick, and 
 adhering very firmly to the wood. The natives break off 
 these branches just before the time of hatching, and expose 
 them to the sun to kill the insect. These twigs are sold 
 under the name of stick-lac. That of Siam is considered the 
 best, that of Assam the next, while that of Bengal in which 
 the resinous coat is thin, scanty, and irregular is the worst. 
 
 According to the analysis of Dr. John, stick-lac has the 
 following composition : — 
 
 An odorous common resin 65-83 
 
 A resin insoluble in ether 16-67 
 
 Colouring matter, analogous to that ) 
 
 of cochineal / 35 
 
 Bitter balsamic matter 2-50 
 
 Dim yellow extract '42 
 
 Acid of the stick-lac — laccic acid '63 
 
 Fatty matter, like wax 2 -50 
 
 Skins of the insects and colouring matter 2 - o8 
 
 Salts 1*04 
 
 Earths '62 
 
 Loss 3'9 6 
 
 IOO'OO 
 
STICK-LAC. 223 
 
 Hatchett's analysis yielded : 
 
 Resin 68 - o 
 
 Colouring matter io'o 
 
 Wax 6 - o 
 
 Gluten 5-5 
 
 Foreign bodies 6*5 
 
 Loss : 4 "O 
 
 IOO'O 
 
 Stick-lac is a dark red transparent resin, breaking with 
 a vitreous fracture. It imparts a purple colour to the 
 saliva, and has a bitter, astringent taste. It yields to water 
 only a part of its colouring matter. It is insoluble in fixed 
 and essential oils, but is slightly soluble in alcohol. Borax 
 solution exercises a special solvent power upon it. 
 
 Dilute sulphuric or hydrochloric acid dissolves the 
 colouring matter freely, and the solution thus obtained is 
 sometimes used in Europe to produce scarlet shades on 
 woollen goods, to which it yields its colour without the 
 employment of mordants, and the colours so obtained, 
 although not so brilliant as those of cochineal, are less 
 easily affected by perspiration. Alkalis and soap, how- 
 ever, impart to them a purple hue. Stick-lac is still much 
 used in the East, both in the dyeing of woollen goods and 
 Morocco leather. Besides the stick-lac just described, 
 there are two products prepared from it, known in com- 
 merce as "seed-lac" and "shell-lac." 
 
 Seed-lac is obtained from the stick-lac by removing 
 the resinous concretion from the twigs, reducing it to a 
 coarse powder, and then triturating it with water in a 
 mortar. By this means the greater part of the colouring 
 matter is dissolved, and the granular portion which remains 
 after being dried in the sun constitutes seed-lac. 
 
 It contains less colouring matter than stick-lac, and is 
 much less soluble. The results of Hatchett's analysis were: 
 
224 DYEING AND CALICO PRINTING. 
 
 Resin 8S'5 
 
 Colouring matter 2 "5 
 
 Wax 4 "5 
 
 Gluten 20 
 
 Loss 2 - 5 
 
 I00"0 
 
 Shell-lac is obtained by putting the seed-lac into an 
 oblong bag of cotton cloth, which is held over a charcoal 
 fire until the contents begin to melt, when the bag is 
 twisted so as to strain the liquified resin through its 
 interstices, whence it is allowed to drop upon smooth stems 
 of the banyan tree. In this way the resin spreads into 
 thin plates, in which state it is found in commerce. The 
 Pegu stick-lac being very dark coloured furnishes a shell- 
 lac of a corresponding dark hue, and therefore of inferior 
 value. A stick-lac of an intermediate kind comes from the 
 Mysore country, which yields a brilliant lac-dye and a good 
 shell-lac. According to the analysis of Hatchett it con- 
 tains : 
 
 Resin 909 
 
 Colouring matter - 5 
 
 Wax 40 
 
 Gluten 28 
 
 Loss 1 '8 
 
 Lac-Dye and Lac-Lake have been imported into this 
 country from India since the year 1796, and are both pre- 
 pared by acting on stick-lac by a weak alkaline ley. If 
 lac-lake is required, this liquor is added to a solution of 
 alum, and the precipitate thus produced is collected, 
 moulded into small lumps about two inches square, and 
 dried. John, who has analysed it, finds it to contain : 
 
MUREXIDE. 225 
 
 Colouring matter 50 
 
 Resin 40 
 
 Alumina 9 
 
 Foreign matters 1 
 
 100 
 
 The details of the process for preparing lac-dye are kept 
 secret, but it appears to be produced by evaporating the 
 above described alkaline solution carefully, in flat dishes, 
 either by artificial heat or by the heat of the sun It 
 forms cakes about 2^ inches square, and varying from *5 
 to '8 inches in thickness. It is principally shipped from 
 Calcutta. 
 
 These products, especially lac-dye, are used in England 
 as substitutes for kermes in the production of scarlets; 
 they require no mordants on woollen cloths, although a 
 little chloride of tin is usually added to prevent the colour 
 assuming a purple hue. From two to three parts of lac- 
 dye are equal to one of cochineal. 
 
 The tinctorial power of these various dyestuffs may be 
 determined by the same processes as those employed for 
 cochineal. 
 
 Some years ago, Messrs. E. Brooke and Co., of Man- 
 chester, introduced a lac-dye much Superior to that im- 
 ported from India; it is prepared by treating stick-lac with 
 weak ammonia, and adding chloride of tin to this solution, 
 a fine red precipitate is thus formed, which when collected 
 is ready for use. 
 
 MUREXIDE. — Although this colour has now been super- 
 seded by those derived from coal-tar, it may be noticed 
 here as an example of the great assistance which chemical 
 science has rendered to the art of calico printing. 
 
 In the year 1776, the illustrious Swedish chemist, Scheele, 
 discovered in human urine a compound to which he gave 
 the name of uric acid. In 18 17, Brugnatelli found that 
 Q 
 
226 DYEING AND CALICO PRINTING. 
 
 nitric acid transformed uric acid into a substance which he 
 named erythric acid, but which was subsequently changed to 
 alloxan by Liebeg and Wohler. In 1818, Prout found that 
 this substance, in contact with ammonia, gave a beautiful 
 purple-red colour, which he called purpurate of ammonia, 
 and which is identical with the product known by the name 
 of murexide since the classical researches of Liebig and 
 Wohler, published in 1837. Thus the matter rested until the 
 year 1851, when Dr. Saac observed that alloxan, although 
 itself a colourless crystallised compound, coloured the skin 
 red when it came in contact with it. This led him to infer 
 that alloxan might be employed to dye woollens red, and 
 further experiments showed that if woollen cloth were pre- 
 pared with a salt of tin, passed through a solution of 
 alloxan and then submitted to a gentle heat, a most 
 beautiful and delicate pink colour was produced. 
 
 In 1856, MM. Deponilly, Lauth, Meister, Petersen, and 
 Albert Schlumberger, applied it as a dyeing material for 
 silk and wool, and obtained red and purple colours, by 
 mixing the murexide with corrosive sublimate, acetate of 
 soda, and acetic acid. For printing on cotton fabrics, a 
 mixture of murexide and nitrate of lead, or acetate of zinc, 
 properly thickened was applied to the cloth. It was then 
 allowed to dry for a^day or two, and the colour fixed by 
 passing it through a mixture of corrosive sublimate, acetate 
 of soda, and acetic acid. Very large quantities of printed, 
 coloured, and mixed fabrics were thus produced in 1855 
 and 1856, but the introduction of the aniline colours, with 
 their superior stability and brilliancy of shade, soon put an 
 end to the use of this colouring matter. 
 
 The large quantities of uric acid required to supply the 
 demand for murexide which arose during these years were 
 obtained from Peruvian guano. The guano was first 
 treated repeatedly with hydrochloric acid, and washed until 
 all the soluble matters were removed, leaving an insoluble 
 
MUREXIDE. 
 
 227 
 
 mass consisting chiefly of sand and uric acid. Many pro- 
 cesses have been devised for converting this crude uric acid 
 into murexide, one of the most simple being to treat it with 
 nitric acid of specific gravity 1-40 ; when the action was 
 complete, warm water was added to the mass and the 
 whole thrown on a filter. The filtrate, which contained 
 alloxan, alloxantin, and nitrate of urea was evaporated care- 
 fully, at a temperature of 175 F., to such a degree, that 
 when left to cool it became a brownish-red, or violet solid, 
 called by its discoverer carmin de poupre; this was the 
 substance used for printing in the manner above described. 
 
CHAPTER VIII. 
 
 ORCHIL, CUDBEAR, AND LITMUS. 
 
 About the year 1 300, an Italian named Federigo, who 
 during his travels in the East had observed the tinctorial 
 powers of a certain class of plants of low organisation called 
 lichens, introduced the colour into Florence under the name 
 of orchil. For this discovery he was ennobled ; moreover, 
 he and his family accumulated a very large fortune, as for 
 many years the whole of the orchil used in Europe was 
 supplied from Florence. 
 
 At first the 'weeds,' or lichens used for the production of 
 this colour were collected on the shores of various islands 
 in the Mediterranean, but on the discovery of the Canary 
 Islands in 1402, large quantities were obtained from thence. 
 Later again they were imported from Cape Verd, and now 
 they are also obtained from Madagascar, Zanzibar, Angola, 
 Lima, and various parts of South America. 
 
 Lichens are small perennial plants belonging to the class 
 Cryptogamia. ■ They require free access to light and air, 
 and grow either on the stems and leaves of trees, or on 
 rocks, or damp soils. The fructification of the lichens con- 
 sists of a round or linear, convex or concave cup, called 
 apothecium, or shield, at first closed, but afterwards ex- 
 panding and producing a disc or nucleus, in which the 
 spores are embedded. The shield is surrounded by a 
 border, which originates either from the substance of the 
 thallus, or from the shield itself, or from both. This class 
 of plants forms the principal flora found in the arctic circle, 
 but the species growing there are not employed to produce 
 
MANUFACTURE OF ORCHIL. 
 
 229 
 
 Fig. 11. 
 
 the colouring matter orchil, the varieties used for this pur- 
 pose being found in warmer, and especially in tropical 
 climates. 
 
 The two principal species growing on the shores of the 
 countries already mentioned are the Roccella tinctoria and 
 the Roccella fiiciformis , which are 
 imported and sold as weed of 
 the countries from which they 
 have been brought, as for exam- ^ 
 pie, 'Lima weed,' which is the 
 Roccella fuciformis, and 'Val- 
 paraiso weed,' which is the Roc- 
 cella tinctoria. Of the species 
 growing inland the Variolaria 
 dealbata, found on the rocky 
 parts of the Pyrenees, the Vario- 
 laria orciua of Auvergne, and the Lecouaria tartarca of 
 Sweden, are the most important. 
 
 Lichens do not contain any colouring matters ready 
 formed, but certain colourless compounds, which, under 
 the influence of ammonia and the oxygen of the atmo- 
 sphere, give rise to orchil. The chief colour-yielding 
 principles existing in these lichens are erythrin, lecanoric 
 acid, and evernic acid. 
 
 The manufacture of orchil from lichens was for many 
 centuries conducted in wooden troughs 7 feet long, 3 feet 
 wide, and 9 to 12 inches high, which were closed by 
 wooden lids furnished with hinges. Two hundred parts of 
 the lichens were placed in the trough, together with two 
 hundred and forty parts of decomposed urine, and the mix- 
 ture well worked every three hours for forty-eight hours. 
 Five parts of slaked lime, one part of arsenious acid, and 
 one-quarter part of alum were then added, and the whole 
 well stirred and allowed to ferment. The stirring was 
 repeated from time to time for a month. The contents of 
 
230 DYEING AND CALICO PRINTING. 
 
 the trough were then removed into casks and left to stand ; 
 the colouring power of the mass being much improved by 
 keeping. 
 
 The ammonia necessary for the production of the colour- 
 ing matter is derived from urea, a substance present in 
 urine, and which under the influence of a special ferment 
 becomes converted into ammonium carbonate, as shown in 
 the following equation : — 
 
 CH 4 N 2 + 2 OH 2 = (NH 4 ) 2 .C0 3 . 
 
 Urea. Water. Ammonium 
 
 carbonate. 
 
 The addition of lime then decomposes the ammonium car- 
 bonate, with formation of calcium carbonate and liberation 
 of ammonia. 
 
 This primitive and offensive process was materially im- 
 proved soon after the introduction of coal-gas, by substi- 
 tuting the ammoniacal liquor obtained in that manufacture 
 for putrid urine. 
 
 M. Freson, a large manufacturer of orchil, in France, 
 found when the weeds were bruised in a mortar with 
 water, and then shaken in a coarse sieve, that a white 
 floculent matter was separated, which contained nearly 
 the whole of the colouring matter of the lichens. 
 
 In order to cany out this process on a large scale, the 
 lichens, after being freed as far as possible from earthy 
 impurities and washed, are ground between millstones with 
 water into a pulp. This pulp is then carefully washed 
 several times with cold water, and the washings thrown on 
 a loosely woven woollen sieve, which retains only the 
 ligneous fibre. To the filtrate a small quantity of bichlo- 
 ride of tin is added, which coagulates the colour-giving 
 principles and determines their precipitation. This deposit 
 is collected, washed, and placed in troughs with the requi- 
 site quantity of ammonia. It is stirred from time to time 
 for a month, during which period the colour acquires great 
 intensity, and a beautiful extract is obtained, which can be 
 
MANUFACTURE OF ORCHIL. 
 
 231 
 
 used either for printing or for dyeing. As Gauthier de 
 Claubry has pointed out, however, if the lichens are left 
 for any length of time in contact with water, the colouring 
 principle is decomposed and dissolves, so that considerable 
 loss would occur unless the operations are carried on very 
 rapidly. 
 
 The following process was communicated to the author 
 by Mr. J. A. Bouck, as the one usually adopted in England: 
 
 The best orchil is prepared from the Rocella tinctoria. 
 The weed is picked by hand or otherwise, torn or cut into 
 small pieces, placed in earthenware mugs or jars, and as 
 much ammonia at 4 Twaddle added as will cover the 
 weed in the jars. The jars are then covered with wooden 
 lids, and kept at a temperature of about 70 F. Fermenta- 
 tion soon commences, and the mass should be turned over 
 and well stirred at least three times daily. The fermenta- 
 tion is allowed to go on until the whole of the colouring 
 matter is extracted from the weed, which generally takes 
 place in fourteen to twenty-one days, if the temperature 
 has been properly attended to. If the fermentation is 
 allowed to go on for too long a time the colouring matter is 
 entirely destroyed, and a dirty brown substance produced. 
 
 The mass is taken out of the jars and pressed, and the 
 liquor so obtained is the blue orchil of commerce, and 
 should show 8° Twaddle gravity. The red orchil is 
 obtained by heating the blue orchil at a very low tempera- 
 ture, so as to drive off the ammonia. This operation is 
 best conducted in a double-cased steam pan. 
 
 The beautiful purple and mauve colours obtained on silk 
 and wool from orchil are extremely fugitive, losing their 
 brilliancy on exposure to light or to the influence of weak 
 acids, such as sulphurous acid, which is so abundantly 
 produced in our manufacturing districts. M. Marnas, of 
 Lyons, however, succeeded in 1856 in making orchil colours, 
 which gave fast purples and mauves. 
 
232 DYEING AND CALICO PRINTING. 
 
 In the first instance, as suggested by Dr. Stenhouse, the 
 lichens were treated with milk of lime, but it was after- 
 wards found to be more advantageous to extract them 
 with a dilute solution of ammonia; the colour-giving 
 principle is thrown down from the clear solution by hydro- 
 chloric acid, and collected on a filter. This precipitate, 
 after being well washed, is dissolved in caustic ammonia, 
 and the ammoniacal liquor kept at an even temperature of 
 1 5 3° to i6o° R, for twenty to twenty-five days, when the 
 colour-giving principles of the lichens are transformed into 
 a new series of compounds, the most important of which 
 is of a magnificent purple colour. In order to separate 
 this, chloride of calcium is added to the liquid, which pre- 
 cipitates it as a fine purple lake. This, after being washed 
 and dried, is sold under the name of French purple. 
 
 To dye silk or wool with French purple, it is simply 
 necessary to mix the lake with its own weight of oxalic 
 acid, boil with water, and then filter. The oxalate of lime 
 remains on the filter, whilst the colour passes through in 
 solution, and is added to a slightly ammoniacal liquid in 
 the dyebeck; all that is now necessary is to dip the silk or 
 wool in the beck, when it will become dyed a magnificent 
 purple or mauve. In order to dye cotton, it must be mor- 
 danted with albumen, or prepared as for Turkey red, before 
 putting it in the bath. 
 
 SILK DYED WITH FRENCH PURPLE. 
 
USES OF ORCHIL. 233 
 
 As the lichens imported into this country vary consider- 
 ably in the amount of orchil which they yield, it is of the 
 greatest importance to have a simple and accurate method 
 of ascertaining their commercial values. For this purpose 
 Dr. Stenhouse has devised several processes, the following 
 being an outline of the most recent : — 100 grains of the 
 lichen are macerated with a solution of caustic soda, con- 
 taining 5 per cent, of the hydrate, two treatments being 
 sufficient to extract the whole of the colouring principle. 
 A solution of hypochlorite of soda of known strength is 
 then added to the alkaline extract from a graduated alkali- 
 meter, and as soon as it comes in contact with the soda 
 solution of the lichen it produces a blood-red colour. This 
 changes to yellow in the course of a few seconds, when a 
 fresh quantity of bleaching liquid should be poured into the 
 soda solution, and the mixture again stirred. The operation 
 must be repeated as long as the addition of the hypo- 
 chlorite causes the production of the red colour, care being 
 taken towards the end of the process that only a few drops 
 at a time are added, the mixture being carefully stirred 
 between each addition. By noting how many measures of 
 the bleaching liquor have been required for this purpose, 
 the amount of colouring principle contained in the lichen 
 may be determined. 
 
 The employment of orchil is at the present day compara- 
 tively limited, but it is still used for producing browns, ma- 
 roons, and other dark shades in conjunction with other dye- 
 stuffs. Its chief use is to top cheap indigo blues on woollen 
 goods ; this is effected by lightly dyeing the fabrics with 
 indigo, which is an expensive dye, and then passing it 
 through a bath of orchil, when it acquires a rich purple 
 hue, similar in appearance to one dyed wholly with indigo. 
 
 Robiquet, in 1829, was the first to isolate the peculiar 
 colourless principle, which, when brought in contact with 
 ammonia and oxygen, assumes the fine purple hue of orchil. 
 
234 DYEING AND CALICO PRINTING. 
 
 This principle he named orcin. He obtained it by treating 
 the Variolaria dealbata with strong alcohol, evaporating 
 the solution to an extract, exhausting this with water, and 
 again evaporating to a syrup ; on allowing this to stand for 
 some time crystals were deposited having the form of 
 colourless, quadrangular prisms, which are hydrated orcin, 
 C 7 H 8 2 + OH„; orcin is also produced by the decomposi- 
 tion of various compounds obtained from the lichens, such 
 as evernic acid, lecanoric acid, and erythrin. In 1S67, Sten- 
 house published a process by which it may be easily pre- 
 pared from the latter. Erythrin is dissolved in a slight 
 excess of milk of lime, and boiled for half an hour in a 
 vessel furnished with a long condensing tube, so as to pre- 
 vent the access of air as far as possible, which otherwise 
 would cause the formation of a red-coloured resinous 
 matter. The solution, containing orcin and erythrite, is 
 filtered, the excess of lime removed by passing a stream of 
 carbonic acid gas through it (or more conveniently on a 
 large scale, by exactly neutralising with dilute sulphuric 
 acid), and then, after concentration, it is evaporated to dry- 
 ness over a water bath. As orcin is moderately soluble in 
 hot benzene, whilst erythrite and the dark brown colouring 
 matters are insoluble in that menstruum, advantage is taken 
 of this circumstance to effect their separation. The dry 
 mixture of orcin and erythrite above mentioned is boiled 
 with coal-tar oil boiling between 230 and 300 F. 
 (toluene, &c.) in a flask of tin or copper connected with a 
 condenser: a paraffin bath being employed for heating the 
 flask in order to avoid the risk of charring and destroying 
 the erythrite. As the distillation proceeds, the water con- 
 tained in the mixture of orcin and erythrite distils over 
 with a portion of the coal oil. After twenty or thirty 
 minutes' digestion, the flask is disconnected from the con- 
 densing apparatus, and the nearly colourless solution of 
 orcin in coal oil poured out. As soon as it is cool it should 
 
PREPARATION OF ORCIN. 235 
 
 be agitated in a glass flask with about one-tenth of its 
 bulk of water, in order to extract the orcin from the coal 
 oil, which may then be separated from the aqueous solution, 
 poured back into the tin flask, and the digestion continued 
 as before. When this operation has been repeated three or 
 four times, the solid matter in the tin vessel is extracted 
 by boiling water, filtered when cold to separate resinous 
 matters and other impurities, and then evaporated nearly 
 to dryness. After standing several days a large quantity 
 of erythrite crystallises out. This may be purified by 
 washing with cold spirit, pressing, and recrystallising once 
 or twice from hot water, with the addition of some animal 
 charcoal. The aqueous solutions obtained by the above 
 method, on cooling, usually deposit a quantity of nearly 
 colourless crystals of orcin, and the remainder in solution is 
 readily obtained by sufficient concentration. If it is wished 
 to obtain colourless orcin, it is only necessary to purify by 
 a second treatment with benzene, and recrystallisation from 
 water. The advantage of this method consists not only in 
 enabling us to separate orcin and erythrite easily, but also 
 to obtain pure orcin from mixtures contaminated with 
 large quantities of colouring matter. When operating on 
 very large quantities of the mixture, however, it is easier 
 and more advantageous to separate the orcin from the ery- 
 thrite by crystallisation, as the latter is much more soluble 
 in cold water than the former. Orcin can readily be ob- 
 tained colourless by distilling it in vacuo. 
 
 Orcin melts below 21 2° R, losing its water of crystallisa- 
 tion, and becoming anhydrous. Heated with care to 
 550 F. it distils unchanged. It has a sweet, somewhat 
 astringent taste, and is freely soluble in alcohol or ether, 
 and in hot water. When crystallised from ether the 
 crystals are anhydrous. It is neutral to test-paper, but in 
 its chemical constitution, and in many of its reactions 
 there is a close analogy to phenol. Thus, when in a state 
 
236 DYEING AND CALICO PRINTING. 
 
 of fusion, it decomposes alkaline carbonates, and it also 
 precipitates silica from alkaline silicates. According to De 
 Luynes, on the other hand, Jt precipitates several of the 
 alkaloids from their acid solutions. 
 
 When dissolved in water or alcohol, it does not give pre- 
 cipitates with bichloride of mercury, sulphate of copper, 
 tannin, gelatin, or acetate of lead. With subacetate of 
 lead it gives a white precipitate, and with persalts of iron 
 a red one. With bleaching powder it gives a purple-red 
 colour, which rapidly changes to a deep yellow. Treated 
 with chlorate of potash and hydrochloric acid, or with 
 hydrate of chlorine, it yields a pentachlorinated compound 
 C 7 H 3 C1 5 2 . With bromine it yields, besides the mono- 
 bromicin of Lampater,* two definite products — a penta- 
 bromo and a tribromo derivative. With picric acid it gives a 
 beautiful crystalline compound, having the appearance of 
 bichromate of potash; this is soluble in alcohol and ether, 
 but is decomposed by benzene into picric acid and orcin. 
 
 When orcin is acted on by cold fuming nitric acid it 
 yields a red-coloured matter, which is precipitated on the 
 addition of water. De Luynes has observed that a red 
 colouring matter is produced when orcin is exposed to 
 the vapour of nitric acid by placing it under a bell-jar along 
 with a vessel containing the concentrated acid. The crys- 
 tals first become brown, then red, and after a few days the 
 transformation is complete. It differs from the compound 
 obtained on exposing orcin to the action of ammonia and 
 oxygen, for it dyes silk and wool red without a mordant, and 
 yields a purple colour with alkalis, which is changed to red 
 by acids. Although boiling nitric acid converts orcin into 
 oxalic acid, nitro substitution compounds may be obtained 
 by using proper precautions. Stenhouse preparedf trinitro- 
 orcin C 7 H 5 (N0 2 ) 3 02, by dissolving orcin in a small 
 
 *Ann. Chem. Pharm., cxxxiv., 258. 
 + Proc. Roy. Soc, xix., 410. 
 
NITRO-DERIVATIVES OF ORCIN. 237 
 
 quantity of water, and adding the solution slowly to nitric 
 acid of specific gravity 1-45, previously cooled in a freezing 
 mixture of ice and salt. The pale brown solution thus 
 obtained is then gradually added, with constant stirring, 
 to concentrated sulphuric acid, also cooled by means of a 
 freezing mixture. The temperature during the operations 
 should not at anytime be allowed to rise above 14 F. 
 
 After twenty minutes the resulting pasty mass is poured 
 into a mixture of crushed ice and water, which precipitates 
 the crude nitro-compound as a yellow or orange-coloured 
 granular powder. After being washed and crystallised from 
 boiling water, it forms large yellow needles, soluble in 
 alcohol, ether, and benzene. It dyes the skin yellow, like 
 picric acid, but is tasteless. It volatilises slightly at 21 2° F., 
 melts at 290 F., and decomposes with slight explosion 
 immediately afterwards. 
 
 Two isomeric mononitro-orcins* C 7 H 7 (N0 2 )0 2 have also 
 been obtained, being produced along with other com- 
 pounds by the action of a mixture of nitric and nitrous 
 acids on an ethereal solution of orcin. The a-nitro-orcin 
 crystallises in long orange-red needles, which melt at 
 248 F., and are readily soluble in alcohol and ether, whilst 
 fi-nitro-orcin forms short lemon-yellow needles, which melt 
 at 2 39 F. 
 
 The most important property of orcin, however, in con- 
 nection with the arts, is that, when moistened and exposed 
 to the atmosphere in presence of ammonia, it becomes con- 
 verted into a beautiful purple colour. Robiquet, who first 
 observed this reaction, gave to this new substance the 
 name of orcein. Dumas, who further studied the subject, 
 considered the transformation to be 
 
 C 7 H 8 2 + NH 3 + 30 = C 7 H 7 N0 3 + 2 OH 2 . 
 Orcin. Ammonia. Orcein. Water. 
 
 De Luynes, who has also examined this remarkable re- 
 * Weselsky Deut. Chem, Ges. Ber. f vii., 439. 
 
238 DYEING AND CALICO PRINTING. 
 
 action, says that when dry gaseous ammonia and dry orcin 
 are used no coloration takes place, but that when orcin is 
 dissolved in a solution of ammonia and maintained at a 
 temperature of 122 F. for several days, care being taken 
 to replace the ammonia as it evaporates, a highly coloured 
 violet solution is obtained, which, after being filtered and 
 evaporated, leaves a violet residue of orcein. The insoluble 
 residue on the filter, after being washed with dilute solu- 
 tion of ammonia, is dissolved in boiling alcohol and 
 allowed to cool. A brown deposit is thus obtained, which 
 under the microscope is seen to consist of a multitude of 
 small colourless crystals, more or less contaminated with a 
 brown resinous substance. This crystalline deposit is in- 
 soluble in water and ammonia, but is slightly soluble in 
 alcohol, to which it imparts a crimson colour. It yields 
 with alkalis a violet solution, and with sulphuric acid a deep 
 blue. De Luynes also found that orcin under the influ- 
 ence of ammonia can be oxidised by other agents than oxy- 
 gen. Thus, by boiling a solution of orcin and ammonia 
 with potassium bichromate or permanganate, or with per- 
 oxide of barium, these agents were reduced, and orcein 
 formed. When the ammoniacal solution of orcein is put 
 under a bell-jar in presence of nitric oxide, the gas is 
 rapidly absorbed, and a colouring matter of great intensity 
 produced. 
 
 De Luynes and Lionet have also obtained several orcin 
 derivatives by heating equivalent quantities of crystallised 
 orcin, and of the iodides of the various alcohol radicles. 
 With the iodides of methyl, ethyl, and amyl, they obtained: 
 
 Methylorcin C 7 H 7 (CH 3 )0 2 . 
 
 Ethylorcin C 7 H 7 (C 2 H 5 )CL. 
 
 Amylorcin C 7 H 7 (C 5 H u )0 2 . 
 
 The first two bodies are liquid and syrupy, the third cry- 
 stallises in needles. 
 
ER YTHRIN. 
 
 239 
 
 By heating a mixture of 1 molecule of orcin with 2 mole- 
 cules of the iodide, and potassium hydrate, they obtained : 
 
 Diethylorcin C 7 H a (C 2 H 5 ) 2 2 . 
 
 Diamylorcin C 7 H 6 (C 5 H U ) 2 02. 
 
 These two bodies are syrupy. The first distils unchanged 
 at 470 to 480 F. 
 
 Lastly, on adding the iodides and potash in great excess, 
 they state that trimethylorcin, C 7 H 5 (CH 3 ) 3 2 ; triethyl- 
 orcin, C 7 H 5 (C 2 H 5 ) 3 2 ; and triamylorcin, C 7 H 5 (C 5 H n ) 3 
 2 are formed. Trimethylorcin is liquid and distils without 
 alteration at about 480 F., and triethylorcin distils at 
 5io°F. 
 
 Erythrin. — This compound, one of the most interesting 
 substances existing in the orchil weed, was discovered by 
 Heeran in the Roccella fuciformis, and has since been 
 studied by Schunck, Stenhouse, Hesse, and De Luynes. 
 
 The best process for its extraction is that devised by 
 Stenhouse, which -consists in macerating the lichen with 
 lime and water : 3 lbs. of the Roccella fuciformis are macer- 
 ated for twenty minutes with milk of lime, made by slaking 
 y 2 lb. of lime in 3 gallons of water. This maceration is 
 repeated three times. The weaker solutions may be em- 
 ployed with advantage to extract a fresh quantity of the 
 weed. The solution is filtered, and hydrochloric acid added 
 to the filtrate in order to precipitate the erythrin, which is 
 collected on a filter, and washed once or twice with water 
 to remove the chloride of calcium and excess of hydro- 
 chloric acid, this is most conveniently done by stirring it 
 up with water and again throwing it on a filter. 
 
 Erythrin, or erythric acid, C 20 H 22 O 10 , is almost insoluble 
 in cold water, and requires two hundred and forty parts of 
 boiling water for solution ; on cooling, it is deposited in the 
 form of a colourless crystalline powder, which is only 
 slightly soluble in cold ether and alcohol, but more soluble 
 
240 D YEING AND CALICO PRINTING. 
 
 in hot alcohol, from which it crystallises in stellate groups 
 of needles. The alcoholic solution is colourless, tasteless, 
 and inodorous. Erythrin is soluble in solutions of caustic 
 and carbonated alkalis, and in lime and baryta water. On 
 the addition of an acid to any of these solutions it is thrown 
 down unchanged as a bulky, white, gelatinous precipitate; 
 but if the solutions are boiled, or if they are kept for any 
 length of time, the erythrin is decomposed and is no longer 
 separated on the addition of an acid. Its ammoniacal 
 solution becomes red on exposure to the atmosphere. The 
 alcoholic solution gives a white precipitate with subacetate 
 of lead, but none with the neutral acetate : on the addition 
 of perchloride of iron it acquires a beautiful purple or violet 
 colour. 
 
 The researches of Schunck, published in 1842, threw 
 much light on the composition of this compound, showing 
 the relation that existed between the orcin of Robiquet, and 
 oj Heerjln's erythrin and 'pseudo-erythrin' (ethylic orsellinate). 
 At the same time he proved that orcin was the only 
 immediate colour-producing principle of the series. On 
 boiling erythrin with weak baryta water, he found that it 
 was decomposed into two substances, one of which he 
 named picroerytJirin, and the other he recognised as the 
 orcin of Robiquet. The following equation will show the 
 decomposition : — 
 
 C 20 H 2 ,O 10 + BaH 2 2 = C 12 H 1G 7 + C 7 H 8 2 + BaC0 3 . 
 
 Erythrin. Picroerythrin. Orcin. 
 
 Lecanoric Acid. — Schunck, by exhausting Variolaria 
 orcina and other lichens of the genera Lccanora and Vario- 
 laria with ether, obtained a white crystalline substance to 
 which he gave the name of lecanorin or lecanoric acid, 
 C 16 H u 7 . When this substance is boiled with alcohol for 
 some hours orcin is separated, and an ether formed which 
 is identical with the pseudo-erythrin of Heerin. The 
 decomposition is as follows : — 
 
LECANORIN. 241 
 
 C 16 H H 7 + C 2 H 5 .OH = C 8 H 7 4 .C 2 H 5 + C 7 H 8 2 + CO,. 
 
 Lecanorin. Alcohol. Ethylic orsel- Orcin. 
 
 linate. 
 
 Schunck also found that when lecanorin is boiled with 
 
 baryta water it is decomposed with formation of orcin and 
 
 barium carbonate. 
 
 C lfl H u 7 + 2BaH 2 2 - 2C 7 H 8 3 + 2BaC0 3 + OH 2 . 
 Lecanorin. Orcin. 
 
 Lecanorin or lecanoric or orsellic acid may be obtained 
 from the Lecanora tartarea or Roccella tiuctoria by mace- 
 rating it with milk of lime in a manner similar to that 
 employed for the preparation of erythrin, but according 
 to Hesse* it is then contaminated with a yellowish brown 
 colouring matter, from which it is extremely difficult to 
 separate it. He prefers, therefore, to exhaust the lichen 
 with ether, and after removing the latter by distillation the 
 pale green crystalline residue is dissolved in milk of lime, 
 and after being allowed to settle, the clear liquor is 
 syphoned off and carefully neutralised with sulphuric acid. 
 The precipitate thus obtained is recrystallised from hot 
 alcohol, which on cooling deposits the lecanoric acid in the 
 form of prismatic crystals. To obtain it quite pure, the 
 crystals are treated with a quantity of ether, insufficient to 
 dissolve the whole, and filtered. The residue left on 
 evaporation is then dissolved in hot alcohol, from which 
 the pure acid separates on cooling. 
 
 Crystallised lecanoric acid has the composition C 16 H u 7 
 + OH j, but the water is easily removed by heating it to 
 212 F. It is insoluble in cold water, but freely soluble in 
 hot alcohol and in ether. Its solution reddens litmus. It 
 dissolves readily in alkaline solutions, from which it is 
 reprecipitated on the addition of an acid ; if, however, it 
 has been boiled or allowed to stand some considerable 
 time before adding the acid, no precipitate is obtained, the 
 lecanoric acid having become changed into orsellinic acid. 
 
 * Ann. Chem. Pharm., cxxxix., 22. 
 
242 DYEING AND CALICO PRINTING. 
 
 It is insoluble in all weak acids except acetic. It yields a 
 fugitive red colour with bleaching powder, and its alcoholic 
 solution gives a crimson colour with persalts of iron. 
 Strong nitric acid converts it into oxalic acid. It yields 
 salts with metallic oxides. When heated in the open air 
 on platinum foil, it melts and then catches fire, but in a 
 closed tube it gives off a dense vapour, which condenses in 
 the upper part of the tube, and after a time solidifies to 
 a crystalline mass of orcin. 
 
 As already stated, when lecanoric acid is boiled with 
 alcohol it yields etliylic orsellinate. This ether may also be 
 conveniently prepared from erythrin by boiling it for some 
 hours with eight parts of absolute alcohol, evaporating, and 
 crystallising the residue (which consists of the ether, mixed 
 with picroerythrin and resinous matters) from water. The 
 ether may be obtained quite pure by recrystallisation from 
 benzene. It is but slightly soluble in cold water, and 
 crystallises from its solution in hot benzene, or boiling water, 
 in colourless plates or needles. It is very soluble in 
 alcohol or ether, and also in dilute alkalis, being precipi- 
 tated unchanged from the latter on the addition of an acid. 
 Its ammoniacal solution on exposure to the atmosphere 
 assumes a wine-red tint. Stenhouse has prepared the cor- 
 responding methyl compound by a similar process, and has 
 also examined the iodine substitution products of the 
 two ethers. 
 
 When erythrin is boiled with amylic alcohol, amylic 
 orsellinate and picroerythrin are formed. 
 
 CjoHooOjo + C 5 H n .OH = C 12 H 1G 7 + C 5 H u .C 8 H 7 4 . 
 
 Erythrin. Amyl Alcohol. Picroerythrin. Amylic orsellinate. 
 
 On distilling off the excess of the alcohol, and boiling the 
 residue with water, the picroerythrin dissolves and crystal- 
 lises out on cooling in white silky needles, of the formula 
 C 12 H 1C 7 , 30H 2 . This is the best method of preparing 
 this substance in the pure state. 
 
PICROER YTHRIN.—ER YTHRITE. 
 
 243 
 
 Picroerythrin, as already mentioned, was discovered by 
 Schunck, who obtained it from the products of the decom- 
 position which erythrin undergoes when boiled with water. 
 It is only slightly soluble in cold water, but readily in hot, 
 being deposited, on cooling, either in the form of needles or 
 of shining plates. With perchloride of iron it produces a 
 beautiful purple colour. It yields a precipitate with sub- 
 acetate of lead, but none with the neutral acetate. When 
 dissolved in ammonia and exposed to the atmosphere it 
 gives, like lecanorin, a red colouring matter. Cold alkaline 
 solutions readily dissolve picroerythrin, but when boiled it 
 is decomposed with formation of orcin, erythrite, and an 
 alkaline carbonate, as shown in the following equation : 
 
 C 12 H 16 7 + BaH 2 2 = C 7 H 8 2 + C 4 H 10 O 4 + BaC0 3 . 
 
 Picroerythrin. Orcin. Erythrite. 
 
 Heated alone in a tube it yields a sublimate of orcin. 
 
 For a long time it was a matter of doubt, and gave rise 
 to much discussion as to whether the lecanoric acid 
 described by Schunck, and the a and j3 orsellic acids 
 obtained by Stenhouse, respectively from South American, 
 and South African Roccella, were different compounds or 
 not. The latter chemist, however, after a long series of 
 experiments, has satisfactorily established that all three 
 acids are identical.* 
 
 Erythrite, erythromannite, or pseudo-orciii, derives its 
 name from IpvSpog red, in allusion to the red colour obtain- 
 able from the lichen. This beautiful substance, which was 
 discovered by Stenhouse, is interesting not only as being 
 obtained from one of the most important of the colour- 
 giving principles of the lichens, but also from its chemical 
 relations, and from the various products obtained by the 
 action of reagents on it. It is not only formed by the 
 decomposition of erythrin, or rather from the picroerythrin 
 obtained by the splitting up of the erythrin, but it also 
 *Jour. Chem. Soc, xx., 221. 
 
244 DYEIXG AND CALICO PRIXTIXG. 
 
 exists ready formed in the Protcoccus vulgaris, from which 
 it may be readily extracted. The method of preparing 
 erythrite from erythrin has already been described when 
 treating of orcin. 
 
 When pure it crystallises in large colourless prisms 
 belonging to the dimetric system, which are readily soluble 
 in water, but only slightly so in alcohol ; it is insoluble in 
 ether. As it possesses a slightly sweet taste, Berthelot 
 was led to consider it as a sugar. This view, however, is 
 incorrect, its chemical reactions and decomposition showing 
 that it is a true tetratomic alcohol. It does not reduce 
 ammonia tartarate of copper, and it has no rotatory power 
 on polarised light. It fuses at 248 R, and may be heated 
 to 482° F. without undergoing decomposition. When 
 mixed with twelve times its weight of concentrated hy- 
 driodic acid and distilled, it yields butylic iodide C 4 H 9 I. 
 By the action of a mixture of concentrated nitric and sul- 
 phuric acids it is converted into a nitric ether, tctranitro- 
 crythrile, C 4 H 6 4 (N0 2 ) 4 , which is very explosive, detona- 
 ting sharply when struck. By prolonged treatment with 
 nitric acid, oxalic acid is produced, but no mucic acid. On 
 fusing erythrite with potassium hydrate, hydrogen is 
 evolved, and acetate and oxalate of the alkali produced. 
 
 Usnic Acid, Evernic Acid, and Cladonic Acid. — The first 
 of these, usnic acid, C^H^O-, which exists in the various 
 species of Usnea, as well as in the Ramalina and Evernia, 
 was discovered by Knop, and has since been carefully 
 examined by Stenhouse, and by Hesse. It may be readily 
 prepared from the Usnea florida by extracting it with milk 
 of lime and precipitating the solution by hydrochloric acid. 
 The impure usnic acid thus obtained may be purified by 
 dissolving it in hot alcohol to which caustic soda has been 
 added, filtering, and then adding excess of acid. After 
 being collected and washed with cold alcohol, it should be 
 recrystallised from boiling alcohol, in which it is only 
 
£ VERNIC A C ID. —CLAD ONIC A CID. 245 
 
 sparingly soluble. It forms bright yellow needles which 
 melt at 397 F. 
 
 By extracting Evernia prunastri with milk of lime in the 
 usual way, a mixture of usnic acid and evernic acid C 17 H 16 7 
 is obtained, from which the latter may readily be separated 
 by treating the product with hot alcohol. This leaves the 
 comparatively insoluble usnic acid, but dissolves the evernic 
 acid, and deposits it again on cooling in minute colourless 
 crystals, which, after being purified by recrystallisation 
 melt at 327 F. 
 
 By the action of alkalis, evernic acid is decomposed with 
 
 formation of eveminic acid, and probably also orsellinic 
 
 acid, 
 
 C n H 16 7 + OH 2 = C 9 H 10 O 4 + C 8 H 8 4 , 
 
 Evernic acid. Eveminic Orsellinic 
 
 acid. acid. 
 
 the latter being resolved by the continued action of the 
 alkali into orcin and carbonic acid. Eveminic acid is readily 
 prepared from evernic acid by boiling it with baryta water, 
 and then adding a slight excess of hydrochloric acid to 
 precipitate the new compound. It closely resembles 
 benzoic acid in appearance, and is only sparingly soluble 
 in cold water, but readily in alcohol or ether. It melts at 
 296 F. When evernic acid is boiled with absolute alcohol, 
 eveminic ether, C 2 H 5 . C 9 H 9 4 is formed, so that unless 
 care be taken in crystallising the acid from hot alcohol 
 considerable loss is apt to occur. 
 
 Cladonic Acid, C 18 H 18 7 , the fi-usnic acid of Hesse, is 
 isomeric with ordinary usnic acid, which it closely resem- 
 bles in appearance. It is obtained from the Cladonia 
 rangiferina by extracting it with a dilute solution of caustic 
 soda, precipitating by hydrochloric acid and recrystallising 
 the product alternately from ether and from alcohol. It 
 melts at 347 F., or about 50 lower than ordinary usnic 
 acid, from which it differs in yielding a sublimate of (3-orciu 
 C 8 H 10 O 2 , a homologue of orcin, when distilled. 
 
246 D YEING AND CALICO PRINTING. 
 
 Orscllinic Acid, or Orsellesic Acid. — This acid was dis- 
 covered by Stenhouse in 1848, and although it does not 
 exist ready formed in the lichens, yet it may readily be 
 obtained from both erythrin and lecanoric acids, two of the 
 colour-giving principles of the lichens, and possibly also 
 from evernic acid. These compounds, when heated for a 
 short time with a solution of an alkali or an alkaline earth, 
 or even by the long-continued action of boiling water itself, 
 yield orsellinic acid. The decomposition which evernic 
 acid undergoes under these circumstances has just been 
 noticed; that of lecanoric acid is exhibited in the subjoined 
 equation. 
 
 C 16 H u 7 + OH 2 = 2C 8 H 8 4 . 
 
 Lecanoric Orsellinic 
 
 acid. acid. 
 
 When erythrin is boiled with water containing lime or 
 baryta it splits up, yielding picroerythrin and orsellinic 
 acid. 
 
 C 20 H 22 O 10 + OH 2 = C 12 H 16 7 + C 8 H 8 4 . 
 
 Erythrin. Picro- Orsellinic 
 
 erythrin. acid. 
 
 The most convenient way of preparing orsellinic acid is 
 to dissolve lecanoric acid in baryta water, avoiding excess 
 of the latter, and then to boil the solution for a short 
 time; care must be taken, however, that the action does 
 not proceed so far as to decompose the orsellinic acid into 
 orcin and carbonic acid. On adding hydrochloric acid to 
 the solution, the new compound is thrown down as a gela- 
 tinous precipitate, which may be purified by crystallisation 
 from water or from alcohol. 
 
 Pure orsellinic acid, C 8 H 8 4 , forms colourless prismatic 
 crystals, which melt at 349 R, and are much more soluble 
 in water and alcohol than lecanoric acid. It is readily 
 decomposed by boiling with alkalis, orcin being formed. 
 C 8 H S 04 = C 7 H 8 2 + C0 2 . 
 
 Orsellinic Orcin. 
 
 Acid. 
 
CUDBEAR. 247 
 
 The orsellinates of the alkalis, and of barium and 
 calcium are readily soluble in water. 
 
 Besides the compounds already described as obtained 
 from the colour-producing lichens, Schunck found that 
 parellic acid, C 9 H 6 4 , sometimes accompanied lecanoric 
 acid. Roccelliuin, C 1S H 16 7 , and roccellic acid, C 17 H 32 4 , a 
 kind of fatty acid, have also been obtained from the 
 Roccella tinctoria,\v\\i\st fi-c/yt/iriu, C 21 H 24 O 10 , was discovered 
 by Menschutkin* in a South American variety of the 
 Roccella fuciformis. It differs from ordinary erythrin by 
 yielding as the ultimate products of its decomposition 
 erythrite and |3-orcin. 
 
 The following summary of the principal facts in connec- 
 tion with the colour-giving principles of the lichens may 
 be found useful : 
 
 1. Lecanoric acid, by the action of alkalis, takes up 
 water, and is converted into orsellinic acid, which subse- 
 quently splits up into carbonic anhydride, C0 2 , and orcin. 
 
 2. Erythrin, by the action of alkalis, yields orsellinic 
 acid and picroerythrin, the latter of which is then decom- 
 posed into erythrite, orcin, and carbonic anhydride. 
 
 3. Everinic acid, by the action of alkalis, yields ever- 
 ninic acid and orcin; the latter, as has been already 
 noticed, being possibly derived from orsellinic acid as an 
 intermediate product of the reaction. 
 
 Cudbear. — The best weed for the preparation of cud- 
 bear is the Lecanora tartarea. It is ground up with 
 ammonia, at 4 Twaddle, into a paste, and allowed to 
 ferment in a similar manner to orchil. When the fermen- 
 tation is complete, the mass is dried in troughs, through 
 which hot water pipes are passed, and in which a roller 
 fitted with small arms revolves, so as to allow the ammonia 
 and water to evaporate more easily. When dry it is 
 powdered, and is ready for the market. It is principally 
 
 *Bull. Soc. Chim., [2], ii., 424. 
 
248 DYEING AND CALICO PRINTING. 
 
 used, either alone or with other dyestuffs, for dyeing 
 woollen goods maroon and various shades of brown. 
 
 Cudbear is occasionally adulterated with common salt, 
 and magenta is sometimes added to improve the colour. 
 
 LITMUS. — The colour called litmus, or lacmus, employed 
 by chemists to detect the presence of free acid or alkali, is, 
 according to Kane, a mixture of several colouring matters, 
 azolitmin, C 7 H 7 N0 4 erythrolcin, erytJirolitmin, and spanio- 
 litmin. De Luynes has succeeded in preparing azolitmin 
 directly from orcin, by boiling one part of that substance 
 with twenty-five parts of crystallised carbonate of soda, five 
 of water, and one of a strong solution of ammonia. The 
 whole is maintained at a temperature of 140 to 167 in 
 a closed vessel, and frequently agitated. A blue liquor is 
 thus produced, which is diluted with water, and hydro- 
 chloric acid added in slight excess. The precipitated 
 colouring matter after being washed and dried, is considered 
 by De Luynes to be pure azolitmin. It is a blue substance 
 which acquires a coppery lustre when rubbed with the nail. 
 The following equation is intended to illustrate the conver- 
 sion of orcin into azolitmin : — 
 
 C 7 H 8 2 + NH 3 + 4 = C 7 H 7 N0 4 + 2OH, 
 Orcin. Azolitmin. 
 
 Azolitmin is almost insoluble in cold water, benzene, or 
 oil of turpentine, but dissolves readily in alcohol, to which 
 it imparts a red colour. When neutralised with an alkali 
 it becomes blue, but is again turned red on the addition of 
 an acid in very slight excess. 
 
 Litmus is manufactured in Holland from the same 
 varieties of lichen as those employed in the production of 
 orchil. The weed is ground and mixed with ammonia and 
 carbonate of potash, and left to ferment until the mass has 
 acquired a purple tint. Lime, potash, and urine are then 
 added, and the whole left until the colour is changed to 
 blue. Plaster of Paris is now mixed with it, and it is 
 
RESORCIN. 249 
 
 moulded into small cubes which, when dried, are ready for 
 use. 
 
 A peculiar blue colour which has a great similarity to 
 litmus, called tournesol en drapeaux, is manufactured princi- 
 pally at Grand-Gallargues, in the south of France, from a 
 species of Euphorbiacese, called Crotoii tinctorium. The 
 sap of the plant is pressed out, and coarse linen is dipped 
 into it, and then placed over vats containing putrid urine to 
 which lime and alum have been added. The cloths, which 
 are moved from time to time, gradually assume a dark blue 
 colour. They are then dipped a second time in the sap, to 
 which some urine has been added, and are dried in the sun. 
 
 These blue cloths are sent to Holland, where they are 
 used for giving a red colour to the outside rind of cheese. 
 
 RESORCIN. — This compound has a very close relation to 
 orcin, the latter in fact being a methyl derivative of the 
 former; for resorcin, C 6 H 4 (OH) 2 , is a di-hydroxyl deriva- 
 tive of benzene; whilst orcin, C 6 H 3 (CH 3 ) (OH) 2 , is the 
 corresponding derivative of toluene, which is methyl ben- 
 zene. As might be expected, it yields colouring matters 
 similar to those obtained from orcin, by exposure to the 
 air in presence of ammonia, but these, which are of a 
 much redder shade than orchil, have not come into general 
 use. 
 
 Resorcin may be prepared in a variety of ways, as by 
 fusing with potassium hydrate certain resins such as gal- 
 banum, asafcetida, gum ammoniacum, and sagapenum, the 
 first mentioned giving the most satisfactory results. In 
 order to extract the resorcin from the fused product it is 
 dissolved in water as soon as it is cold, neutralised with 
 sulphuric acid, and the clear filtered solution shaken up 
 with ether. This takes up the resorcin, which is deposited 
 in the crystalline state on distilling off the ether. It may 
 be purified by distillation. Besides these resins, other sub- 
 stances, when fused with caustic alkalis, yield resorcin, such 
 
250 DYEING AND CALICO PRINTING. 
 
 as paraphcnolsulphonic acid, bromobenzenesulphonic acid, 
 paraiodophenol, and brazilin. Kopp, however, considers 
 the best and cheapest method of preparing this substance 
 to be by the dry distillation of the impure brazilin lake, 
 formed by adding chalk to the wash waters obtained in the 
 manufacture of brazilin from Brazil wood extract, and 
 evaporating to dryness. 
 
 Resorcin is a colourless crystalline compound, closely 
 resembling orcin in its properties and appearance, being 
 very soluble in water, alcohol, and ether. It melts at 
 2io° F., and distils without decomposition at 513 F. 
 
 The behaviour of resorcin with fuming sulphuric acid is 
 very characteristic. It dissolves at first with an orange- 
 yellow colour, which in the course of twenty or thirty 
 minutes changes to a greenish-blue, and ultimately to a 
 pure blue. On warming this solution to 21 2° F. it changes 
 to a fine purple-red. 
 
 Azoresorcin derivatives. — Weselsky,* by treating resorcin 
 with nitrous acid, has succeeded in obtaining colouring 
 matters which rival the aniline colours in the brilliancy 
 and purity of their shades. Diazoresorcin, Ci 8 H 12 N 2 O c , is 
 obtained in brown granular crystals, with a green metallic 
 lustre, on passing nitrous acid into an ethereal solution of 
 resorcin. It is only sparingly soluble in water, but dis- 
 solves in alcohol or acetic acid, forming a dark cherry-red 
 coloured liquid ; its alkaline solutions are of a splendid 
 blue-violet. The action of strong sulphuric or hydro- 
 chloric acid on this substance gives rise to diazoresoriifi)i, 
 C 36 H 18 N 4 9 , which forms small dark red crystals, almost 
 insoluble in water, alcohol, or ether, but dissolving in alka- 
 line solutions with a magnificent crimson colour. When 
 heated with tin and hydrochloric acid, diazoresorufin 
 undergoes reduction, the solution becomes emerald-green, 
 and on cooling deposits pale green needles of hydrodiazo- 
 *Deut. Chem. Ges. Ber., i\\, 613. 
 
FL UORESCEIN.—E OSIN. 2 5 1 
 
 resorufin hydrochloride, CjeH^N 4 9 , 3 HO, which assume 
 the coppery lustre of indigo when exposed to the air. 
 
 On heating diazoresorcin with strong nitric acid it is 
 converted into tetrazoresorchi nitrate, C 18 H 6 N 4 G , (N0 3 ) 3 , 
 which crystallises in garnet-red needles with a brilliant 
 metallic lustre. They are soluble in water and alcohol, 
 and very readily in ether, with a pure indigo-blue colour. 
 By the further action of nitric acid they are converted into 
 tetrazorcsorufin nitrate, C 34 H 6 N 8 9 , (N0 3 ) 6 , the crystals 
 of which closely resemble permanganate of potassium in 
 appearance, and dissolve in water, alcohol, and ether, 
 yielding solutions of a similar colour. These compounds 
 when treated with reducing agents yield new products. 
 
 Fluorescein. — This a compound discovered by Baeyer,* 
 and subsequently examined by Fischer.-f" It is prepared 
 by heating 2 molecules of resorcin with 1 of phthalic 
 anhydride to a temperature of about 390 F. for several 
 hours. A reaction soon sets in, accompanied by the revo- 
 lution of aqueous vapour, and the mass ultimately becomes 
 solid as soon as it is cold. The dark red product is 
 powdered, and boiled with water to remove unaltered 
 resorcin and phthalic anhydride, and if required in a pure 
 state may then be crystallised from alcohol, although with 
 difficulty. 
 
 Pure fluorescein, C H 12 O 4 , is a red crystalline powder, 
 which is almost insoluble in water or ether, and but 
 slightly soluble in alcohol. It is soluble in alkaline solu- 
 tions, that with ammonia being characterised by a beautiful 
 green fluorescence. Fluorescein produces a fine yellow on 
 wool and silk without a mordant. The accompanying 
 beautiful specimen, which we owe to the kindness of M. H. 
 Koechlin, is obtained by tetrabromo-fluorescei'n, or eosin, 
 fixed with a salt of lead. 
 
 * Deut. Chem. Ges. Ber., iv., 662, andfvii., 121 1. 
 
2;2 
 
 DYEING AND CALICO PRINTING. 
 
 
 COLOUR OBTAINED WITH EOSIN. 
 
 When fluorescein is heated with concentrated sulphuric 
 acid, at 21 2° for some time, and the product poured into 
 water, a substance is precipitated which may be obtained 
 in bright red prismatic crystals, and dissolves in alkalis 
 with a blue colour ; this is changed to red by the reducing 
 action of zinc dust, and fabrics dipped into this liquid and 
 exposed to the air become dyed blue, as in the indigo vat. 
 The colour, however, is dull and not fast. 
 
CHAPTER IX. 
 
 QUERCITRON, FUSTIC, PERSIAN-BERRIES, WELD, ALOES, 
 TURMERIC, ANNATTO, ILIXANTHIN, ETC., AND LA-KAO. 
 
 This chapter will be devoted principally to a considera- 
 tion of some of the most useful and important yellow 
 colouring matters used by dyers and calico printers. 
 Besides this, it has been thought advisable to give a short 
 notice of certain yellow-coloured compounds of vegetable 
 origin, which, although they are not commercially of great 
 importance, yet are interesting from a scientific point of 
 view. 
 
 QUERCITRON. — Among the most valuable of the yellow 
 dyes is quercitron, the inner bark of a peculiar species of 
 oak, called the Quercus nigra, or tinctoria. This tree is 
 indigenous to the United States, and is especially found in 
 the forests of Pennsylvania, Georgia, and in North and 
 South Carolina. A chemist of the name of Bancroft first 
 introduced it to the English dyers in the year 1775, and 
 obtained by Act of Parliament the exclusive right of 
 importing this wood. The most esteemed qualities are 
 those shipped from Philadelphia, New York, and Baltimore. 
 
 The bark, after being removed from the tree, is dried, 
 and ground between mill-stones; its value being in propor- 
 tion to the depth of colour and fineness of the powder, for 
 the woody fibre of the bark contains but a comparatively 
 small quantity of the colouring principle, and is not easily 
 reduced to a fine powder. 
 
 A freshly prepared decoction of the bark is transparent, 
 and of a dull orange-red colour, but after a time it becomes 
 
254 
 
 DYEING AND CALICO PRINTING. 
 
 turbid, and yields a yellow crystalline deposit. The super- 
 natant liquor gradually becomes gelatinous, acquiring at the 
 same time a blood-red colour, from this it may be inferred 
 that a slow, but gradual change has taken place, no doubt 
 due to the glucoside being decomposed by a peculiar fer- 
 ment. As the colouring matter thus liberated is rapidly 
 oxidised, and becomes useless as a colour-giving principle, 
 it is important that the decoction should be used as soon 
 as possible after its preparation. 
 
 A freshly made solution gives the following reactions : — 
 Alkalis. Deepen the colour. 
 
 /-Deepens the colour and gives a 
 X brownish-yellow floculent pre- 
 ^ cipitate. 
 
 c Brightens the solution, forming a 
 (_ slight precipitate. 
 Brown precipitate. 
 Yellowish precipitate. 
 r Thick brownish-yellow floculent 
 ( precipitate. 
 
 c Olive green precipitate, the liquor 
 \ becoming yellowish-green. 
 /-Colour the solution green, and 
 «j afterwards give an olive-brown 
 ^ floculent precipitate. 
 c Brighten the liquor and give rise to 
 \ a brown floculent precipitate. 
 /-Decreases the intensity of the 
 
 < colour, but if the liquor is turbid 
 v it renders it clear. 
 
 Reddish floculent precipitate. 
 /• Abundant floculent precipitate. An 
 
 < excess of the reagent decolorises 
 ' the liquor. 
 
 Chevreul was the first chemist who examined this dye- 
 
 Lime Water. 
 
 Alum. 
 
 Protochloride of tin. 
 Bichloride of tin. 
 
 Acetate of lead. 
 Acetate of copper. 
 
 Salts of iron. 
 
 Acids. 
 
 Acetic acid. 
 
 Gelatin. 
 
 Chlorine. 
 
Q UER CITRIN.— Q UER CETIN. 2 5 5 
 
 stuff, and he found it to contain, besides a peculiar tannin, 
 which has since received the name of quercitannic acid, 
 a yellow colouring principle to which he gave the name 
 of quercitrin. This he obtained from quercitron bark 
 by boiling it with water and allowing the solution 
 to stand, when fine laminated crystals were deposited. 
 Bolley* prepares it by exhausting the bark with alcohol, 
 and after precipitating the tannin by gelatin, he concen- 
 trates the solution by evaporation, and recrystallises the 
 quercitrin which separates, from boiling alcohol. It is, 
 however, far more advantageously prepared from the 
 flavin imported from America, some samples of which 
 consist of almost pure quercitrin. On boiling this 
 dyestuff with water and filtering, a solution is obtained, 
 which, on cooling, deposits quercitrin in the crystalline 
 state. Quercitrin forms minute rhombic plates of a pale 
 yellow colour, which are only slightly soluble in ether or 
 cold water, but more readily in boiling water, and easily in 
 alcohol. Alkaline solutions dissolve quercitrin with a 
 greenish-yellow colour which becomes brown on exposure 
 to the atmosphere. The aqueous solution gives a brownish- 
 yellow precipitate with baryta, whilst lime water imparts to 
 it a fine yellow tint. The acetates of copper and lead give 
 a bright yellow precipitate. Its most characteristic re- 
 actions, however, are with perchloride of iron, which gives 
 a greenish-yellow precipitate, and with protochloride and 
 oxymuriate of tin, with which it gives beautiful bright 
 yellow precipitates. 
 
 Rigaud discovered some years ago, that when quercitrin 
 was boiled with water containing 10 per cent, of sulphuric 
 acid, it was decomposed into a body to which he gave the 
 name of quercetin, and a species of sugar to which he 
 assigned the formula C 6 H 12 6 , thus proving it to be a 
 glucoside. The quercetin separates in flocks which, after 
 *Ann. Chem. Pharm., xxxvii., 101. 
 
256 DYEING AND CALICO PRINTING. 
 
 being collected and washed, are crystallised from alcohol. 
 The decomposition which takes place when quercitrin 
 is boiled with acids may be thus represented : 
 
 C^A + OH 2 = C 27 H 18 12 + C 6 H 12 5 .OH 2 . 
 
 Quercitrin. Quercetin. Isodulcite. 
 
 To isolate the saccharine matter, the acid liquid from which 
 the quercetin has been separated is neutralised with baryta 
 to remove the sulphuric acid, and then evaporated, when 
 the sugar is obtained in the crystalline state. Hlasiwetz and 
 Pfaundler, who subsequently examined this subject, found 
 that the sugar, which they call isodulcite, C 6 H 12 5 + OH 2 
 is incapable of fermentation, although it reduces cupric 
 salts. It is isomeric with mannite and dulcite, and when 
 treated with a mixture of concentrated nitric and sulphuric 
 acids it yields a trinitro derivative. 
 
 Quercetin, or its glucoside quercitrin, has been found in 
 a great variety of plants. Rochleder* showed that it 
 exists in the flowers and ripe fruit of the horse chestnut 
 (Aesculus hippocastanum). The robinin obtained by Zwenger 
 and Dronke-f" from the Robina pseudacacia, although differ- 
 ing from quercitrin, when boiled with acid, splits up into 
 quercetin and sugar. Robinin is also found in the flowers 
 of the Carvus mascula. 
 
 Quercetin, C 27 H 18 12 , crystallises in slender needles of a 
 bright yellow colour, and of a much richer hue than quer- 
 citrin. It has no taste, is insoluble in cold, and only 
 slightly soluble in hot water, but is freely soluble in alcohol 
 and in acetic acid. It is also soluble in alkalis, to which 
 it communicates an orange-yellow hue. Its alcoholic solu- 
 tion gives orange precipitates with the salts of lime, baryta, 
 and lead. It assumes an orange colour with perchloride 
 of tin, and gives a green coloration with perchloride of 
 iron. 
 
 * Chem. Centr., iv., 162. 
 
 fAnn. Chem. Pharm. Supplement, i., 257. 
 
QUERCETIN. 257 
 
 Quercetin is decolorised by nascent hydrogen. It dis- 
 solves in concentrated sulphuric acid, forming an acid 
 which dyes woollen a fast yellow colour without a mordant. 
 Schiitzenberger and Berteche have obtained a crystallisable 
 acetic derivative of quercetin by heating it with acetic 
 anhydride. It contains three or four acetyl groups, 
 C 2 H 3 0, in place of the same number of hydrogen atoms. 
 
 According to Hlasiwetz and Pfaundler* a potassium 
 compound of quercetin, having the formula C 27 H 18 12 K 2 0, 
 is obtained on dissolving one part of quercetin in a concen- 
 trated solution of three parts of potassium carbonate, and 
 allowing the solution to cool. It crystallises in slender 
 yellow needles, which cannot be dissolved without decom- 
 position. The corresponding sodium compound has the 
 composition C 27 H 18 12 Na 2 0. 
 
 The same chemists have studied the action of potassium 
 hydrate on quercetin, and find that when one part of this 
 substance is added to a boiling solution of three parts of 
 caustic potash in one of water, and the whole evaporated to 
 dryness, a product is obtained which consists of paradatis- 
 cetin, phloroglucin, and quercetic acid. In order to isolate 
 these, the mass, as soon as it is cold, is dissolved in water 
 and neutralised with hydrochloric acid, which precipitates 
 the paradatiscetin together with some unaltered quercetin. 
 The filtered liquid is then mixed- with one-quarter its bulk 
 of alcohol, and agitated with ether which dissolves the 
 phloroglucin and quercetic acid. To separate these two, 
 the residue left on the evaporation of the ethereal' solution 
 is dissolved in water, and basic acetate of lead added ; this 
 precipitates the quercetic acid, and the clear solution, after 
 the removal of the excess of lead by sulphuretted hydrogen, 
 and evaporation, yields phloroglucin in the crystalline 
 state. The lead quercetate, after being washed, is sus- 
 pended in water, decomposed by sulphuretted hydrogen, 
 *Jour. fur Prak. Chem., xciv., 65. 
 
258 DYEING AND CALICO PRINTING. 
 
 and the lead sulphide separated by filtration : the aqueous 
 solution, when evaporated in vacuo, yields crystallised quer- 
 cetic acid. The paradatiscetin may be purified by dis- 
 solving it in alcohol and precipitating the unaltered 
 quercetin by lead acetate : the alcoholic solution, after 
 the excess of lead has been separated by sulphuretted 
 hydrogen, is concentrated by evaporation, and the parada- 
 tiscetin precipitated by the addition of water. 
 
 Quercetic acid, C 15 H 10 O 7 , crystallises in fine white, silky 
 needles, which are only slightly soluble in cold water, but 
 freely soluble in alcohol, ether, or hot water. Its solution, 
 which has an astringent taste, gives a dark blue coloration 
 with perchloride of iron. An alkaline solution when ex- 
 posed to the air assumes a magnificent crimson colour. 
 Quercetic acid dissolves in sulphuric acid with a reddish- 
 brown tint. 
 
 By the prolonged action of potassium hydrate on 
 quercetin, or better, when quercetic acid is fused with 
 potash, a new acid called quercimcric acid, C s H 10 O 5 , is 
 produced. 
 
 C 15 H 10 O 7 + OH 2 + O = C 8 H O 5 + C 7 H 6 4 . 
 
 Quercetic Quercimeric Protocate- 
 
 acid. acid. chuic acid. 
 
 It forms small prismatic crystals, which are readily soluble 
 in water, alcohol, and ether. When fused with potash it 
 yields protocatechuic acid thus : — 
 
 C 8 H G 5 + O = QHA + C0 2 . 
 
 Quercimeric Protocate- 
 
 acid. chuic acid. 
 
 Paradatiscetin, C 15 H 10 O 6 , which is isomeric with datis- 
 cetin, a substance extracted by Stenhouse from the Datisca 
 cannabina, is deposited from an alcoholic solution in yellowish 
 needles, which are only slightly soluble in water, but very 
 soluble in alcohol or ether. Its alcoholic solution gives an 
 intense purple colour with perchloride of iron. The 
 alkaline solution has a bright yellow colour, which changes 
 
PHLOROGLUCIN. 259 
 
 to green when exposed to the atmosphere. Bromine 
 imparts to a solution of paradatiscetin a red colour, which 
 changes after a little while to a magnificent crimson, whilst 
 chlorine and bleaching powder give a reddish-brown color- 
 ation. Paradatiscetin forms definite compounds with bases ; 
 those of barium and strontium crystallising well. 
 
 Phloroglucin, which was originally obtained as a product 
 of the decomposition of phloretin, separates from its 
 aqueous solution in hydrated crystals, belonging to the 
 trimetric system, and having the formula C 6 H 6 3 20H 2 . 
 They effloresce in dry air, and lose their water of crystal- 
 lisation at 192 F., or in vacuo over sulphuric acid. 
 
 Phloroglucin has a sweeter taste than sugar, and under- 
 goes no change in contact with the air. It melts at 428 F., 
 and may be sublimed at a higher temperature without 
 decomposition. It dissolves in water and alcohol, and still 
 more readily in ether. It gives a precipitate with sub- 
 acetate of lead, but none with other metallic salts. It 
 easily reduces the nitrates of silver and mercury, especially 
 on the addition of ammonia and the application of heat. 
 With perchloride of iron it gives a deep red coloration, and 
 with bleaching powder a yellow tint, which, however, soon 
 disappears. Ammoniacal phloroglucin shaken up with air 
 becomes reddish-brown, and afterwards opaque, giving rise 
 to pJdoramine. Nitric acid converts phloroglucin into 
 ;/ itropliloroglucin. 
 
 When a solution of quercetin in soda is treated with 
 sodium amalgam, it acquires a dark brown colour, which 
 gradually turns to yellow. If hydrochloric acid be then 
 added and the whole shaken up with ether, this extracts 
 three compounds, namely, phloroglucin, a soluble substance 
 having the formula C 7 H 8 3 , and a third which crystallises 
 from hot water in slender prisms, having the composition 
 C 13 H 12 3 . Both these bodies yield protocatechuic acid 
 when fused with potash. 
 
26o DYEING AND CALICO PRINTING. 
 
 When an alcoholic solution of quercetin acidulated with 
 hydrochloric acid is acted on by sodium amalgam, the 
 liquid assumes a fine purple colour, and on concentration 
 yields fine red prismatic crystals analogous to isomorin, a 
 product obtained from moric acid, one of the colouring 
 matters of old fustic. It is easily oxidised and reconverted 
 into quercetin by dissolving it in alcohol with the addition 
 of a small quantity of alkali, and exposing it to the atmo- 
 sphere. It becomes green by the action of alkalis, but 
 re-assumes its red colour on the addition of acids. 
 
 Flavin. — Within the last twenty years a preparation of 
 quercitron bark has been imported into this country from 
 America under the name of flavin; it varies greatly, how- 
 ever, in composition, being sometimes nearly pure quer- 
 citrin, whilst other samples only contain quercetin. Bolley 
 examined a specimen of this substance some years ago and 
 found it to contain about 45 per cent, of quercetin, the re- 
 maining 55 per cent, consisting of woody fibre, together with 
 a small quantity of a peculiar sugar, which was doubtless 
 isodulcite. Flavin, therefore, is in some cases the product 
 of the decomposition of quercitrin, the natural glucoside of 
 the bark, by the action of an acid, and stands in the same 
 relation to it that garancin does to madder. It is easy to 
 understand why it is much cheaper for the dyer and 
 calico printer to use this product than the bark itself, and 
 also why it gives brighter colours. The quantity of colour- 
 ing matter in flavin as compared with bark, is as sixteen to 
 one, or, 1 oz. of flavin is equal to 1 lb. of bark. 
 
 It is now manufactured in England, but the quality is 
 not so good as that imported from America, probably 
 owing to the latter being prepared from the fresh wood. 
 The details of the American process are kept secret, but 
 that followed in England consists in adding 2 tons of 
 bark to a mixture of 4 tons of water, with 2 cwt of oil of 
 vitriol, and passing steam through the mixture for twelve 
 
DYEING WITH QUERCITRON. 261 
 
 hours. When cold it is run upon woollen filters, and 
 after being washed with water until all the sulphuric acid is 
 removed, it is pressed, dried, and sieved. 
 
 Quercitron bark and flavin are chiefly used for dyeing 
 woollen and mixed fabrics. To dye pieces of woollen 
 goods of 22 or 23 lbs., the process and proportions are 
 as follows : For each piece, 2 lbs. of alum and 1 lb. of 
 tartar are put into a vat containing a sufficient quantity of 
 boiling water, and flavin added according to the depth 
 of shade required. The mixture is boiled for a few 
 minutes, a pint of nitrate of tin per piece is then added, 
 and the pieces are placed in the vat and boiled for about 
 an hour. In mixed fabrics the pieces are first treated as 
 above, then well washed until all trace of acid is removed, 
 after which they are passed at width through a bath of 
 sumach, then through muriate of tin, and finally through 
 quercitron bark liquor and alum. If cotton alone is to be 
 dyed, it is done cold, and a little oxymuriate of tin is added 
 to the dyeing liquor. For the annexed sample we are 
 indebted to the kindness of Messrs. Z. Heys and Sons, 
 Barrhead, near Glasgow. 
 
 QUERCITRON YELLOW, 
 
262 
 
 DYEING AND CALICO PRINTING. 
 
 Neither quercitron bark nor flavin are much used in 
 calico printing as a yellow dye, but are employed to impart 
 brown and orange hues to madder and garancin, and to 
 modify the shades produced by sumach, cochineal, and 
 logwood. The mordant employed is either alum, or red 
 liquor (an impure acetate of alumina). When used for this 
 purpose the bath should have a temperature of about 120° 
 or 1 30 R; clear whites are then easily obtained. It is 
 useful also to add a little gelatin to the liquor before using 
 it to precipitate the quercitannic acid, which interferes with 
 the brilliancy of the colours. It is used sometimes also for 
 mixed colours, as in the accompanying sample, printed 
 with a mixture of acetate of chromium, with extract of 
 madder and quercitron, and for which we are indebted to 
 the kindness of M. H. Kcechlin. 
 
 EXTRACT OF MADDER AND QUERCITRON. 
 
 The best method of estimating the value of a sample of 
 quercitron bark or flavin, is to dye some mordanted cloth 
 in the same way as in testing the value of a madder or 
 garancin. 
 
 FUSTIC. — This dyestuff is the wood of a tree belonging 
 to the natural order Urticacece, called Mortis, or Madura 
 
REACTIONS OF OLD FUSTIC. 263 
 
 tinctoria. It is known technically as yellow wood, or old 
 fustic, the best qualities being imported from Cuba and 
 Tampico. Those from the Antilles and Pernambuco are 
 of inferior quality. Some very large logs arrive in this 
 country from India, but they contain very small quantities 
 of colouring matter and are principally used in cabinet- 
 making. 
 
 A decoction of old fustic has a bitter, astringent taste, 
 and gives the following reactions : — 
 
 Alkalis. Change the colour to a reddish-brown. 
 
 Lime water. Changes the colour to reddish-brown. 
 
 Sulphuric, nitric, 
 
 and oxalic acids. 
 
 J- Slight precipitates. 
 
 Acetic acid. 
 
 Ferric sulphate. i 
 
 r Makes the colour of the liquor paler 
 
 \ and brighter. 
 Alum. Bright yellow precipitate. 
 
 Olive brown coloration, and, on stand- 
 ing, a brownish-black precipitate. 
 Sulphate of copper. Dark green precipitate. 
 Protochloride of tin. Golden-yellow precipitate. 
 Acetate of lead. Orange-yellow precipitate. 
 
 Acetate of copper. Brownish-yellow precipitate. 
 Gelatin. Orange-yellow floculent precipitate. 
 
 / Slight precipitate, with a reddish 
 Chlorine. < coloration which disappears when 
 
 v an excess of chlorine is employed. 
 
 In this case, again, Chevreul was the first to isolate the 
 two colouring matters in the wood, the one soluble in water 
 which he named morin janne, the other nearly insoluble 
 which he called morin blanc. He found that the latter 
 compound gave with persalts of iron a dark red coloration, 
 whilst the former assumed a greenish hue in the presence 
 of these salts. In 185 1, Wagner,* considering these colour- 
 
 * Jour, fiir Prak. Chem., li., 82. 
 
264 DYEING AND CALICO PRINTING. 
 
 ing matters to be acids, called the morin blanc, moric acid, 
 and morin jaune, morintannic acid; the latter being identi- 
 cal with the crystalline compound observed by Chevreul in 
 the interior of the logs. 
 
 Hlasiwetz and Pfaundler* since then have very carefully 
 studied these two compounds. In order to obtain them in 
 a pure state, rasped fustic is boiled twice with water, and 
 the solution concentrated to the state of a syrup, when, after 
 a few days, a crystalline deposit takes place, which is col- 
 lected, washed rapidly with cold water, and pressed. The 
 product, which consists of morintannic acid and the calcium 
 compound of moric acid or morin, is treated with boiling 
 water, which leaves the latter, whilst the morintannic acid 
 is dissolved. The insoluble lime compound, after being 
 decomposed by treatment with weak hydrochloric acid, is 
 dissolved in alcohol, from which, on the addition of two- 
 thirds of its bulk of water, it is deposited in the form of 
 yellow needles. To obtain the morintannic acid, the 
 aqueous solution above described is concentrated, and the 
 colouring matter which separates is recrystallised once or 
 twice from water acidulated with hydrochloric acid. 
 
 Morintannic acid, or maclurin, C 13 H 10 O c , as thus pre- 
 pared, is a crystalline powder of a pale yellow colour 
 which is freely soluble in water, requiring only 24. parts of 
 boiling and 64 of cold. It is soluble in alcohol, ether, and 
 wood spirit. It fuses at a temperature of 392 F. and is 
 decomposed at 480 . When heated with a concentrated 
 solution of caustic alkali, it yields phloroglucin and proto- 
 catechuic acid. 
 
 C 13 H 10 O 6 + OH, = C fi H c 3 + C 7 H 6 4 . 
 
 Maclurin. Phloro- Protocate- 
 
 glucin. chuic acid. 
 
 When a moderately concentrated solution of maclurin is 
 heated with zinc and sulphuric acid, it rapidly assumes a 
 red . colour, which gradually changes to orange, and the 
 
 *Ann. Chem. Pharm., cxxvii., 351. 
 
MACHROMIN. 265 
 
 solution then contains phloroglucin and a new substance, 
 machromin, C 14 H 10 O 5 . 
 
 Machromin crystallises in minute tufts of slender needles, 
 and derives its name from the great variety of colours it 
 yields. It is very slightly soluble in water or alcohol, but 
 somewhat more so in ether. Both the crystals and their 
 solutions become rapidly blue on exposure to the air, or in 
 contact with oxydising agents. On adding hydrochloric 
 acid, an amorphous blue precipitate is produced. The 
 alkaline solution likewise assumes a blue colour on exposure 
 to the atmosphere. With perchloride of iron or bichloride 
 of mercury, a solution of machromin assumes a beautiful 
 violet shade, which gradually passes into blue. Nitrate 
 of silver gives a similar coloration, the silver salt being at 
 the same time reduced. Machromin dissolves in sulphuric 
 acid, forming an orange-coloured solution which becomes 
 of an intense green on the application of heat; the colour 
 is not changed by diluting it with water, but assumes a 
 purple hue on the addition of an alkali. 
 
 The blue substance formed by the oxidation of machro- 
 min can be easily obtained by adding to an aqueous solu- 
 tion of that body an excess of perchloride of iron. Dark 
 blue flakes are thus produced, which are collected, washed 
 with water, and dried; after being washed with ether, the 
 new colouring matter is obtained as a brilliant dark blue 
 mass. Its formula appears to be C 14 H 8 5 . Its alcoholic 
 solution is decolorised by the action of zinc, or of sodium 
 amalgam. 
 
 Maclurin when dissolved in alkalis and acted on by 
 sodium amalgam, gives rise to phloroglucin and a new 
 body having the formula C u H 12 5 . 
 
 If maclurin is dissolved in sulphuric acid, after a short 
 time brick-red crystals of riifimoric acid appear, which dis- 
 solve in ammonia with a purple coloration. The same acid 
 is produced if maclurin is boiled with hydrochloric acid. 
 
266 DYEING AND CALICO PRINTING. 
 
 Moric acid, or morin, when pure, crystallises in colourless 
 needles, which have the formula C 12 H 10 O 6 . It is nearly in- 
 soluble in water and bisulphide of carbon, only slightly 
 soluble in ether, but freely so in alcohol. It dissolves in 
 solutions of the alkalis, borates, or phosphates with a 
 yellow coloration, and is precipitated from them on the 
 addition of an acid. Perchloride of iron communicates to 
 its alcoholic solution an olive-green shade. It gives yellow 
 precipitates with salts of zinc, tin, lead, and aluminium, and 
 a dark green precipitate with those of copper. 
 
 Hlasiwetz has obtained well defined salts of this acid 
 with potassium, sodium, calcium, barium, lead, and zinc. 
 Moric acid absorbs ammonia, forming a yellow compound, 
 whilst by the action of bromine it yields tribromomoric 
 acid, C 12 H 5 Br 3 6 . 
 
 Moric acid is transformed into phloroglucin, either when 
 submitted to the action of nascent hydrogen, or by fusing 
 it with caustic alkalis. A solution of moric acid in dilute 
 alkali, when treated with sodium amalgam, at first becomes 
 blue, then green, and finally yellowish-brown ; it now no 
 longer gives a precipitate on the addition of an acid, and 
 on examination will be found to contain phloroglucin. The 
 following equation represents the reaction : — 
 C 12 H 10 O 6 + H 2 = 2 C 6 H c 3 . 
 
 Moric acid. Phloroglucin. 
 
 When an alcoholic solution of moric acid, rendered acid 
 by hydrochloric acid, is treated with sodium amalgam 
 until it acquires an intense purple colour, and is then 
 separated from the excess of sodium amalgam and evapo- 
 rated, it yields brilliant purple crystals of isomoriii, a body 
 having the same composition as morin. Under the influence 
 of alkalis this solution becomes green, and after a time 
 moric acid is re-formed ; this change takes place rapidly on 
 boiling. A solution of isomorin mixed with alum offers a 
 remarkable instance of dichro'ism. If it is diluted, it has a 
 
RELATION OF QUERCETIN TO MORIN. 267 
 
 yellow colour by transmitted light, whilst by reflected light 
 it appears of an uranium green. 
 
 Hlasiwetz thus sums up the analogies between quercetin 
 and moric acid. 
 
 1. Both substances yield a purple compound when the 
 acidulated alcoholic solutions are acted upon by sodium 
 amalgam. 
 
 2. Both substances yield phloroglucin when alkaline 
 solutions are treated by sodium amalgam, although in the " 
 case of quercetic acid other bodies are simultaneously 
 formed. 
 
 3. Both compounds combine with potash and soda. 
 
 4. Fused potash transforms both into phloroglucin. 
 
 5. Both bodies are decomposed by heat, yielding a 
 similar sublimate. 
 
 6. Their solutions yield similar reactions with various 
 reagents. 
 
 This eminent chemist believes that the similarity may be 
 explained if we consider quercetin to be a compound of 
 moric and quercetic acids, thus — 
 
 C 27 H 18 12 = C 12 H 8 5 + C 15 H 10 O 7 . 
 
 Quercetin. Moric acid. Quercetic 
 
 acid. 
 
 Goppelsrceder* has made a very interesting observation 
 which may serve to distinguish moric acid from morintan- 
 nic acid, namely, that a solution of moric acid becomes 
 highly fluorescent on the addition of a small quantity of a 
 salt of aluminium, whilst morintannic acid does not. This 
 reaction is so delicate that moric acid becomes fluorescent by 
 the addition of even one-eight thousandth part of alum, 
 when a ray of light is passed through the solution by means 
 of a lens, whilst if a solution contains only one-quarter 
 millionth part of moric acid the fluorescence may still be 
 seen. He suggests that advantage may be taken of this 
 
 * Bull. Soc. Industrielle de Mulhouse, xxxvii., 899. 
 
268 DYEIXG AND CALICO PRINTING. 
 
 property as a means of testing for small quantities of salts 
 of aluminium. 
 
 Old Fustic is especially used for dyeing wools in yellow 
 and olive-green shades. They are mordanted with alumina 
 for yellow, and with salts of iron for green. By the 
 employment of salts of copper and other mordants, a variety 
 of shades can be obtained. It is much used by dyers, but 
 only to a limited extent by calico printers. If the morin- 
 tannic acid or maclurin be precipitated by means of a little 
 glue or gelatin, much brighter yellows are obtained with 
 alumina mordants. The bright yellows produced by this 
 dye are unfortunately affected by air and light, which com- 
 municate to them an orange hue. Through the kindness of 
 Messrs. Z. Heys and Sons, of Barrhead, near Glasgow, we 
 are enabled to illustrate the effect produced by Fustic. 
 
 FUSTIC 
 
 YOUNG FUSTIC. — Young fustic is derived from a plant 
 whose botanical name is Rhus cotinus, belonging to the 
 same genus as sumach. It grows in the West Indies, the 
 Levant, and also in France and the southern parts of 
 Europe. It is found in commerce in the form of small logs 
 and crooked branches, the wood imported from the West 
 Indies and the Antilles being the finest in quality. 
 
YOUNG FUSTIC. 269 
 
 Young fustic contains a tannin matter, and three colour- 
 giving principles, a red, a brown, and a yellow. The yellow 
 colouring matter was first isolated by Chevreul, who gave 
 it the name of fustin. Preisser states that he obtained it 
 by first precipitating the tannin matter from a decoction of 
 the wood by means of gelatin, filtering, and evaporating to 
 dryness. The residue was treated with ether, and the 
 ethereal solution, mixed with water and hydrate of lead, 
 was placed in a retort, and the ether distilled off. A 
 yellow compound was thus formed which was decomposed 
 by sulphuretted hydrogen, and the liquor on evaporation 
 yielded small yellow crystals of fustin, which were purified 
 by crystallisation from ether. Bolley prepared it from a 
 decoction of the wood by evaporating it to dryness and 
 treating the residue with alcohol, this dissolved the fustin 
 and left the red colouring matter and other substances. 
 The alcoholic solution, on evaporation and addition of 
 water, yields yellow crystals of fustin. He considers this 
 colouring matter to be identical with quercetin, but 
 Schiitzenberger doubts this, as fustin gives an orange- 
 coloured precipitate with protochloride of tin, whilst quer- 
 cetin gives a yellow one. Alkalis, moreover, produce a red 
 coloration with fustin, and an orange-yellow with quercetin. 
 Fustin is soluble in water, alcohol, and ether ; its solutions 
 oxidising rapidly when exposed to the atmosphere, and 
 assuming an orange colour. 
 
 A decoction of the wood gives the following re- 
 actions : — 
 
 Alkalis. Communicate to it a fine orange hue. 
 
 Limeand baryta waters. Bright orange precipitate. 
 Acids. Communicate to it a greenish hue. 
 
 Protochloride of tin. Bright orange precipitate. 
 Acetate of lead. Bright orange precipitate. 
 
 Acetate of copper. Dark red precipitate. 
 
 Ferric sulphate Olive-green precipitate. 
 
270 DYEING AND CALICO PRINTING. 
 
 Like fustin itself, the decoction of the wood becomes 
 orange on exposure to the atmosphere. 
 
 Young fustic dyes wool mordanted with alumina a fine 
 orange colour, but it is easily affected by light; its chief 
 employment is in conjunction with cochineal, to the red 
 colour of which it imparts a brilliant orange hue. It is not 
 used in the dyeing of cotton goods, but is largely employed 
 by tanners in Turkey and in the Tyrol to impart an orange- 
 yellow colour to leather. 
 
 Persian Berries. — These are the fruit of the buck- 
 thorn, and several varieties of RJiamnus, growing in the 
 East, and in the southern countries of Europe, among which 
 may be mentioned the Rhamnus amygdalimis, R. olcoides, R. 
 saxatilis, growing in Persia and Turkey, and the R. infec- 
 lorias growing in Avignon. Spain and the Morea also 
 send considerable quantities to this country. 
 
 Generally speaking, the berries are gathered before they 
 are quite ripe, to which their shrivelled appearance is due; 
 they have a yellowish-green colour, and are about the size 
 of small peas. They only give good results when quite 
 fresh; after being kept a year or two they lose much of 
 their value, yielding far less brilliant colours. The yellower 
 they are, the lower the price they command in the market ; 
 whilst if they are brown or black, they are rejected as 
 being old, or injured by damp. Amongst the dealers, they 
 usually bear the name of the country from which they 
 are imported; thus there are Avignon berries, Turkish 
 berries, &c. ; amongst dyers and calico printers, however, 
 all the varieties are called Persian berries, the best being 
 imported from that country. 
 
 Persian berries have a disagreeable, bitter flavour, and an 
 unpleasant odour. A freshly prepared decoction, which has 
 a brownish-green colour, gives the following reactions : — 
 Alkalis. Change the colour to orange. 
 
 Acids. Render it slightly turbid. 
 
PERSIAN BERRIES. 27 1 
 
 Nitric acid. Brightens the liquor. 
 
 f Changes the colour to a greenish- 
 Lime water. \ ,. . .. « ! .. ■ 
 I yellow, causing a slight precipitate. 
 
 j Weakens the colour, but does not 
 
 1 produce a precipitate. 
 
 / Causes no immediate change, but 
 Acetate of lead. \ after a time the liquid becomes 
 
 I turbid. 
 
 Acetate of copper. Slight dirty yellow precipitate. 
 
 Sulphate of copper. Colours the liquor greenish-yellow. 
 
 Ferric sulphate of iron. Colours the liquor greenish-yellow. 
 
 _. , , . . . . r Greenish-yellow coloration ; slight 
 
 Protochlonde of tin. { . . 
 
 I precipitate. 
 
 — . . j Slightly turbid ; a floculent precip- 
 
 l itate forming on standing. 
 ( Deepens the colour to red, after- 
 l wards changing it to yellow. 
 These berries yield to water three principles, — a very 
 bitter compound, a red colouring matter which becomes 
 brown on contact with the atmosphere, and a yellow 
 colouring matter. 
 
 Kane was the first to carefully examine the colouring 
 matters existing in Persian berries. For this purpose he 
 extracted them with ether, and on evaporating the solution 
 obtained fine golden-yellow crystals, to which he gave the 
 name of Chrysorhamnin, and assigned to them the formula 
 C^H^On. When a solution of this body was boiled in con- 
 tact with the air, or in the presence of oxidising agents, he 
 found that it was converted into a new substance very 
 soluble in water, having the formula C 23 H 24 14 . This sub- 
 stance, which he named xanthorhamnin, is also contained 
 in the ripe berries, or in those that have been kept some 
 time. 
 
 A few years afterwards Gellatly* investigated this subject, 
 
 * Edinburgh New Phil. Jour., vii., 252. 
 
272 DYEING AND CALICO PRINTING. 
 
 employing anhydrous ether , and obtained a substance which 
 crystallised in pale yellow silky needles. It appears to be 
 a different product to that obtained by Kane. Gellatly 
 called it Xanthorhamniii, and considered it to have the 
 formula C 23 H 28 O u . He found also that when this body 
 was boiled with dilute sulphuric acid it was decomposed 
 into glucose, and a new colouring principle which, on 
 cooling, is deposited from the liquid as a yellow crystalline 
 powder. He gave it the name of rhamnetin, and represen- 
 ted the reaction which takes place by the following equa- 
 tion : — 
 
 C 23 H 28 O u + 3OH, = 2C 6 H 12 O a + C n H 10 O 5 . 
 
 Xanthorhamnin. Glucose. Rhamnetin. 
 
 He was certainly the first to point out the fact that 
 the colouring matter of Persian berries was a glucoside. 
 Hlasiwetz* from a comparison of the analyses came to the 
 conclusion that xanthorhamniii and rhamnetin were identi- 
 cal with quercitrin and quercetin. 
 
 Bolleyf* noticing the discrepancy between the properties 
 of the xanthorhamniii described by Kane, and that des- 
 cribed by Gellatly, re-examined these substances, and came 
 to much the same conclusion as Hlasiwetz. Schutzen- 
 berger and Berteche subsequently studied the subject, but 
 failed to throw any additional light on it. There can be 
 no doubt that the product they obtained, and to which they 
 gave the name of chrysorhamnm, is identical with the 
 rhamnetin of Gellatly. They do not agree with Bolley in 
 considering this compound to be identical with quercetin, 
 nor do they believe xanthorhamnin to be the same body 
 as quercitrin. 
 
 In 1866, Lefort, studying these questions, obtained two 
 colouring matters from the berries, the first of which, a 
 yellow crystalline body, he named rJiamuagin, whilst the 
 
 *Ann. Chem. Pharm., cxii., 107. 
 + Ann. Chem. Pharm., cxv., 55. 
 
SUMMAR Y OF RESULTS. 273 
 
 other, which he calls r/iamnin, is a yellow amorphous 
 powder. In 1869 he published a paper stating that these 
 two substances were isomeric, having the formula C 12 H 12 5 
 4- 20H 2 . Rhamnagin is converted into rhamnin by 
 the action of dilute acids without formation of sugar. 
 According to Schiitzenberger, however, rhamnagin, when 
 boiled with dilute sulphuric acid, is converted into rhamne- 
 tin, and a sugar isomeric with mannite. 
 
 2 C 12 H 10 O 7 +3OH0 = C 12 H 10 O 5 + 2 C 6 H u 6 . 
 
 Rhamnagin. Rhamnetin. Sugar. 
 
 We may conclude from the somewhat conflicting results 
 of these various researches that there is in Persian berries 
 a glucoside, crystallising in yellow silky needles, to which 
 the following names and formulae have been given: — 
 
 — Chrysorhanmin C 23 H 22 O n . Kane. 
 
 Xanthorhamnin ... C 23 H 23 O u . Gellatly. 
 
 Quercitrin C 33 H 30 O T . Bolley. 
 
 Rhamnasrin ) ^ TT ^ ^ TT ,", 
 
 This compound, on being boiled with sulphuric acid, 
 yields a sugar and a yellow powder, to which the subjoined 
 names and formulae have been assigned : — 
 
 Rhamnetin C u H 10 O 5 . Gellatly. 
 
 Quercetin C 27 H 18 12 . Bolley. 
 
 Chrysorhamnin ... C 12 H 10 O 6 . Schiitzenberger 
 
 and Berteche. 
 Schiitzenberger and Berteche have obtained a well defined 
 acetyl derivative of rhamnetin by heating that body with 
 anhydrous acetic acid, in closed tubes, to 285 ° F. They 
 assign to it the formula C 12 H 7 (C 2 H 3 0) 3 5 . It has a pale 
 yellow colour ; is insoluble in water, but crystallises from 
 alcohol. 
 
 Schiitzenberger remarks that the only difference between 
 moric acid and rhamnetin, (or his chrysorhamnin) is that 
 the latter contains two equivalents more of hydrogen. 
 
 C 12 H 8 5 + H 2 = Ci 2 H 10 O 5 . 
 
 Moric acid. Rhamnetin. 
 
 T 
 
274 DYEING AND CALICO PRINTING. 
 
 M Kopp has also drawn attention to the fact that the 
 melin or rutin obtained by Stein* from the Waif a (the un- 
 developed flower buds of the Sophora japonica), may be 
 considered as rhamnetin combined with one equivalent of 
 glucose and one of water, thus : — 
 
 C 18 H. 2 A, = C 12 H 10 O s + C 6 H 12 O + OH 2 . 
 
 Melin. Rhamnetin. Glucose. 
 
 It will be readily perceived, even from this short notice, 
 that the nature of the colouring matter of Persian berries is 
 still involved in much obscurity. It is probable, however, 
 that a careful comparison of the products of the decom- 
 position of the glucosides found in this dyestuff, and in 
 quercitron, would throw much light on the subject. 
 
 Persian berries are chiefly used by calico-printers for pro- 
 ducing bright yellows or greens in steam styles. To obtain 
 yellows, a freshly prepared decoction is mixed either with 
 a little red mordant (sulpho-acetate of alumina) or with 
 oxy-muriate of tin. The mixture is thickened, printed on, 
 and the fabric steamed. The two samples, illustrating the 
 effects obtainable with Persian berries, we owe to the 
 courtesy of Messrs. Wood and Wright. 
 
 WM 
 
 to' -<s(te to 
 
 PERSIAN BERRIES (YELLOW). 
 
 1 Jour, fur Prak. Chem., lxxxv., 351. 
 
D YE TNG WITH PEE STAN BEEEIES. 
 
 275 
 
 To produce greens, the decoction is mixed with prussiate 
 of tin, thickened, printed on, and the fabric steamed. In 
 this latter process, the prussiate of tin is decomposed, the 
 tin uniting with the yellow colouring matter, whilst the 
 hydroferrocyanic acid is decomposed, forming Prussian 
 blue, the two colours together producing green on the 
 fabric. 
 
 PERSIAN BERRIES (GREEN). 
 
 In woollen dyeing, the goods are first mordanted by being 
 passed through a nearly boiling solution containing alum, 
 and cream of tartar or salts of tin ; the decoction of berries 
 is then added, and the goods kept in until the required 
 shade is obtained. 
 
 The decoction of berries is very apt to ferment and 
 become ropy ; but this may be prevented by the addition 
 of a little carbolic acid. 
 
 A very brilliant yellow lake is also produced from Persian 
 berries, the mode of manufacture was long kept secret 
 by the Dutch. It was imported from Holland under the 
 name of 'Dutch yellow.' It is obtained by preparing a 
 decoction of the berries in water, in which a certain quantity 
 of alum is dissolved; to this solution pure carbonate of 
 
276 DYEING AND CALICO PRINTING. 
 
 lime is added, which, as it falls, brings down with it the 
 whole of the colouring matter. The shade of the lake may- 
 be varied by the addition of a little turmeric, fustic, quer- 
 citron, or dyewood to the alum solution. The lake thus 
 produced is moulded into small lumps, which are dried 
 in the shade. It is chiefly used by paper stainers, and 
 for coarse decorations, such as theatrical scene painting, &c. 
 
 Weld. — Weld, Reseda luteola, is a variety of mignionette, 
 which used to be cultivated in England, and is still grown 
 in France, and other parts of the continent. It is an 
 herbaceous plant, growing to a height of from 3 to 4 feet, 
 which is sown in the spring of one year, and reaped in the 
 autumn of the following year ; being either pulled like flax 
 or mown. It is dried in the shade, and has a yellow or 
 greenish yellow tint according to the care bestowed on the 
 drying. The upper parts of the plant contain the most 
 colouring matter, especially the leaves and the external 
 parts of the seeds. It is a very valuable dye when fixed 
 on wool, both on account of the brilliancy of the colour 
 produced, and also from its power of resisting light, heat, 
 and acids. 
 
 A decoction of weld has a pale yellow colour when 
 freshly prepared, but soon becomes turbid, and deposits a 
 compound of the colour-giving principle with oxide of iron 
 as a greenish-brown precipitate. When kept for some time, 
 it assumes a reddish tint. It is slightly acid, and gives the 
 following reactions : — 
 
 ( Change the colour to a golden- 
 
 )W. 
 
 Alkalis. 
 
 ( yel^ 
 
 Lime water, or any ") _^ , 
 
 , \- Deepen the colour, 
 
 calcareous waters. ) 
 
 Baryta water. 
 Nitric acid. 
 
 c Beautiful yellow floculent precipi- 
 { tate. 
 
 r Deepens the colour, but gives no 
 \ precipitate. 
 
PREPARA TION OF L UTEOLIN. 277 
 
 Other acids. Render the liquid turbid. 
 
 Alum. Slight yellow precipate. 
 
 Protochloride of tin. Abundant yellow precipitate. 
 
 Acetate of lead Abundant yellow precipitate. 
 
 r Olive-brown coloration, and, on 
 Ferric sulphate 1 t ,- 1 • -, 
 
 r ( standing, a brown precipitate. 
 
 Acetate of copper. Yellowish brown precipitate. 
 
 Gelatin. Renders the liquor slightly turbid. 
 
 r Changes the colour of the liquid to 
 r , , . J brown and gives a floculent pre- 
 
 1 cipitate; excess of the reagent 
 
 partially decolorises the liquid. 
 
 _ ,. , r Acts like the alkalis, then gives a 
 
 Potassium dichromate 1 . :, , 
 
 ( precipate in yellow plates. 
 
 Chevreul, who was the first to isolate the colouring mat- 
 ter of weld, obtained it in pale yellow needles, to which he 
 gave the name luteolin. Moldenhauer, who studied it some 
 years afterwards, found its formula to be C 20 H u O 8 . 
 
 Schiitzenberger and Paraf* give the following interesting 
 and novel process for the preparation of pure luteolin. 
 The upper part of the weld plant is cut into small pieces 
 and treated with alcohol in a displacement apparatus. The 
 solution thus obtained is concentrated, and on the addition 
 of water greenish flocks are deposited, which are collected 
 and placed with water in a glass cylinder fitting tightly in 
 a strong steel tube firmly closed. It is then subjected to a 
 temperature of 480 F. for twenty minutes and allowed to 
 cool. On opening the cylinder the whole of the upper 
 portion is found to be lined with brilliant golden-yellow 
 crystals of luteolin, whilst a thick resinous cake remains at 
 the bottom. It is necessary to submit the crystals thus 
 obtained to a second treatment, in order to obtain them 
 quite pure. Pure luteolin crystallises in quadrangular 
 needles, which have an astringent, bitter taste. It sublimes 
 
 *Schutzenberger, Traite des Matieries Colorante, ii., 457. 
 
278 DYEING AND CALICO PRINTING. 
 
 with partial decomposition at a temperature of 6oo° F. It 
 is freely soluble in alcohol, sparingly so in ether, and but 
 very slightly soluble in hot water. Perchloride of iron im- 
 parts a green colour to its solution, even when very dilute. 
 By the action of oxidising agents, such as bichromate of 
 potash, it assumes a magnificent yellow colour similar to 
 that produced on woollen fabrics. Luteolin is not de- 
 composed when boiled with dilute sulphuric acid, and is 
 therefore not a glucoside. 
 
 Hlasiwetz and Pfaundler consider luteolin to be an 
 isomeride of paradatiscetin. Rochleder and Brever,* who 
 have also examined this colouring principle, state that when 
 fused with caustic potash, phloroglucin and protocatechuic 
 acid are produced. Adopting Moldenhauer's formula for 
 luteolin, the following equation represents the decomposi- 
 tion : — 
 
 C 20 H u O 8 + 2OH0 + 2 = 2C 6 H 6 3 + C 7 H O 4 + COo. 
 
 Luteolin. Phloroglucin. Protocate- 
 
 chuic acid. 
 
 The introduction of quercitrin and flavin has entirely 
 superseded the use of weld in England, but it is still used 
 to some extent for dyeing woollen goods on the continent, 
 where it is employed with alumina mordants to produce 
 various brilliant shades of yellow, and with a mixture of 
 alumina and iron mordants to dye olive-greens. 
 
 Aloes. — This drug is the thickened juice of various 
 species of Aloc\ a genus of plants belonging to the liliaceous 
 order. The species from which it is most commonly derived 
 are the Aloe vulgaris or sinuta, A. socotrina, A. spicata, 
 A. arborescens, A. africaua, and A.ferox. 
 
 The best sorts of aloes are prepared by boiling down in 
 a copper or cast iron pot the juice which exudes from the 
 leaves, which are cut off for that purpose close to the plant. 
 
 There are four principal varieties of aloes known in com- 
 
 * Jour, fur Prak. Chem., xcix., 433. 
 
VARIETIES OF ALOES. 279 
 
 merce, namely, Socotrine aloes, Barbadoes aloes, Natal 
 aloes, and Cape aloes. 
 
 Socotrine aloes, or, as it is also called, Bombay aloes 
 and Zanzibar aloes, is imported from the east coasts of 
 Africa, and southern Arabia, via Bombay, in kegs or in 
 boxes lined with tin. When of good quality it is of a 
 dark reddish-brown, and has an odour recalling that of 
 saffron. If moistened with alcohol, and examined under 
 the microscope, it will be seen to contain a great number 
 of minute crystals. When opaque and liver-coloured, it is 
 sometimes called 'Hepatic aloes,' or 'Liver aloes.' 
 
 Barbadoes aloes, made from the A. vulgaris, is of a deep 
 brown colour, and when breathed on has an odour some- 
 what resembling the last-named variety of aloes, but easily 
 distinguishable from it. In thin fragments it is orange- 
 brown, and translucent. 
 
 Natal aloes, which has been imported from that place in 
 considerable quantity since 1870, is quite unlike ordinary 
 Cape aloes, and is distinguished by containing a peculiar 
 principle, nataloin. It is of a greyish-brown colour, and 
 very opaque. The aloe which yields it is a large plant, 
 and has not, as yet, been identified with any of the known 
 species. 
 
 Cape aloes is produced in largest quantity near Algoa 
 bay, in the Cape Colony, chiefly from the species Aloe 
 spicata, A. africana, A.ferox, and A.aborescens; it is known 
 in commerce as Aloe capensis. Cape aloes has a brilliant 
 conchoi'dal fracture, and a peculiar odour by which it may 
 readily be distinguished from the other kinds ; it is trans- 
 lucent in small splinters, which are of an amber colour by 
 transmitted, but very dark by reflected light ; it yields a 
 pale yellow powder. 
 
 Aloes has an intensely bitter flavour, and a strong aromatic 
 odour ; it is moderately soluble in cold water, and freely 
 soluble in hot water, alcohol, ether, and essential oils. It 
 
2 8o DYEING AND CALICO PRINTING. 
 
 contains three substances, two of which are soluble in water, 
 and form in Barbadoes aloes about 70 per cent, of the mass ; 
 the third is insoluble in water. 
 
 From the aqueous solution of aloes, Messrs. T. and H. 
 Smith, of Edinburgh, succeeded, in 1850, in isolating a 
 compound, to which they gave the name of aloin. In the 
 process they adopted, Barbadoes aloes is treated with cold 
 water, and evaporated in vacuo to the consistence of a 
 syrup ; this is allowed to stand out of contact with the air 
 for a few days, when a yellow crystalline mass is deposited. 
 This is collected, pressed, re-dissolved in cold water out of 
 contact with the air, and again evaporated in vacuo. The 
 process is repeated a third time, when the alo'iu crystallises 
 out nearly pure in the form of a straw-yellow crystalline 
 mass, readily soluble in boiling alcohol, from which it is 
 deposited in silky tufts of yellow rhombic plates. Accord- 
 ing to Tilden,* aloin may be readily prepared from selected 
 Barbadoes aloes, which should have a bright colour and 
 opaque appearance, by dissolving it in boiling water 
 slightly acidulated with hydrochloric acid, and evaporating 
 the filtered solution to a syrupy consistence. In the course 
 of a few days it deposits a lemon-coloured crystalline mass 
 of aloin, which only requires to be freed from the mother 
 liquor by pressure, and then recrystallised, in order to ob- 
 tain it in a pure state. Aloin, or Barbalohi, is only slightly 
 soluble in cold water and ether; freely soluble in hot water, 
 alcohol, acetic acid, and alkalis. Its solutions are rapidly 
 oxidised in contact with the air if an alkali be present, 
 assuming a brown colour, especially if heated. 
 
 Stenhouse, who in 1850 analysed the product prepared 
 by Messrs. Smith, found that when dried at 21 2° F. it had 
 the formula C 17 H 1S 7 ; but if dried in vacuo at the ordinary 
 temperature it still retained 1 molecule of water of crystal- 
 lisation. He found also that when aloin in cold aqueous 
 
 * Pharm. Jour. [3.] ii., 845. 
 
NATALOIN.- SOCALOIN. 281 
 
 solution is treated with an excess of bromine, it forms a 
 compound in which three equivalents of hydrogen are 
 replaced by bromine, yielding bromalo'in, C 17 H 15 Br 3 7 . 
 This is soluble in boiling alcohol, and separates from the 
 solution on cooling in shining yellow needles, grouped in 
 stars much larger than those of aloi'n. It is less soluble in 
 cold water and alcohol than aloi'n. Tilden has also pre- 
 pared the corresponding chloralo'in C 17 H 15 C1 3 7 . 
 
 According to Rochleder, aloi'n on boiling with dilute 
 sulphuric acid is resolved into glucose and rottlerin, the 
 decomposition being 
 
 C 17 H 18 7 + 20H 2 - QH 12 6 + C n H 10 O 3 . 
 
 Alo'in. Glucose. Rottlerin. 
 
 Fliickiger* found that Natal aloes contained a different 
 principle from Barbadoes aloes, which can be readily 
 extracted by treating the drug with its own weight of 
 spirit at a temperature of about 1 io° F. ; this dissolves the 
 amorphous portion and leaves the crystals, which may be 
 purified by pressure and recrystallisation from hot spirit. 
 Nataloin, C 25 H 2S 17 , crystallises in thin, bright yellow scales, 
 which are sparingly soluble in absolute alcohol and in ether, 
 more so in methyl alcohol, but only slightly soluble in water. 
 When treated with nitric acid it yields picric and oxalic 
 acids, but no chrysammic acid, showing that it differs 
 essentially from barbaloin. Histed, whilst examining 
 Socotrine aloes, succeeded in isolating a peculiar principle 
 distinct from both those already described, and which 
 Fliickiger, who subsequently investigated the subject, 
 named Socalom, C^H^O^ + 50H 2 . It crystallises in 
 tufts of acicular prisms, which are much more soluble than 
 nataloin. 
 
 Kosmann,-f* who experimented on Cape aloes, found that 
 the portion soluble in water and that which is insoluble 
 
 * Arch. Pharm. [2.] cxlix., 11. 
 fBull. Soc. Chem., 1863, p. 530 
 
282 DYEING AND CALICO PRINTING. 
 
 both had the same percentage composition. The soluble 
 compound is a yellow amorphous mass, composed of 
 agglomerated granules, which he supposes to be an oxi- 
 dised product of aloin formed during the concentration of 
 the sap, thus: — 
 
 C 17 H ls 7 + O + 2 OH, = CtfHjAfl. 
 
 Aloin. Soluble aloes. 
 
 The compound insoluble in water is formed in a similar 
 manner : — 
 
 3 C 17 H ls 7 + 3 + 60H 2 = C ;i H ,Ao. 
 
 Aloin. Insoluble aloes. 
 
 On being boiled with sulphuric acid these bodies yield 
 glucose, and various acids of a yellowish-brown colour 
 possessing but little interest, 
 
 6C 17 H 22 O 10 = QoHsAi + 2C oH 3i 15 + 2C H 12 O fi + 4 OH 2 . 
 Soluble aloes. Aloeresic acid. Aloeretic acid. Glucose. 
 
 CsoHfflOu + iSO + 80H 2 = C^CV 
 Aloeresic acid. Aloeretin. 
 
 According to Hlasiwetz, when aloes is boiled with dilute 
 sulphuric acid paracoumaric acid, C 9 H 8 3 is obtained, 
 which, by fusion with potash, is converted into paraoxy- 
 benzoic acid, C 7 H 6 3 . When either aloes or barbaloi'n is 
 fused with potassium hydrate it yields the last mentioned 
 acid, and also orcin, the colour-giving principle of the 
 lichens (p. 233). 
 
 Schunck, who many years ago studied the action of nitric 
 acid on the aloin from Barbadoes aloes, found that it gave 
 rise to two compounds, which he named aloetic acid, and 
 ckrysammic acid, respectively. 
 
 To prepare aloetic acid, one part of aloes is heated with 
 eight parts of nitric acid of 1*3 specific gravity ; as soon as the 
 violent oxidising action which ensues is terminated, the 
 solution is concentrated, and water added, when it yields 
 on cooling a yellow powder, which is a mixture of impure 
 aloetic and chrysammic acids. This is washed with cold 
 water, and treated with boiling alcohol, which dissolves only 
 
CHR YSAMMIC A CII). 283 
 
 the aloetic acid ; on cooling, the alcoholic solution deposits 
 the acid in the form of an orange-yellow crystalline powder. 
 
 According to Finck,* however, the best method of separa- 
 ting the acids is to convert them into potassium salts, and 
 then to treat the mixture with cold water, which dissolves 
 only the aloetate. The solution when mixed with barium 
 acetate and evaporated, yields crystals of barium aloetate, 
 from \vhich, after purification, the aloetic acid may be 
 separated by means of nitric acid. 
 
 Aloetic acid C 14 H 4 (N0 2 ) 4 2 , is only slightly soluble in 
 cold water, but freely so in hot water and in alcohol. It is 
 soluble in alkalis with a red colour, whilst with ammonia it 
 forms an amide having a violet colour. By long continued 
 boiling with nitric acid, it is oxidised and converted into 
 chrysammic acid. The alkaline aloetates are soluble and 
 crystalline, those of the heavy metallic oxides are insoluble. 
 
 Chrysammic acid, C u H 4 (N0 2 ) 4 0i, is obtained by digest- 
 ing aloes with nitric acid, specific gravity 1*35 (nine parts) 
 until all action ceases, distilling off most of the nitric acid, 
 and after washing the residue with a small quantity of 
 water, digesting it for six or eight hours with an equal 
 weight of nitric acid of specific gravity 1-45. It is then 
 thrown into water, and the yellow floculent precipitate 
 collected and washed with boiling water until the water 
 passing through assumes a purple colour. Tilden (loc. cit.) 
 prefers to prepare it from barbaloi'n itself, which by the 
 action of cold fuming nitric acid is converted into a mix- 
 ture of chrysammic, aloetic, oxalic, and picric acids. After 
 washing the product with cold water, which removes the 
 two last mentioned acids, it is boiled with fuming nitric 
 acid for a considerable time, in order to convert the aloetic 
 into chrysammic acid. The crude acid obtained by either 
 of these processes is purified by converting it into the 
 potassium, or calcium salt, and recrystallising. On adding 
 
 *Ann Chem. Pharm., cxxxiv., 236. 
 
284 DYEING AXD CALICO PRINTING. 
 
 dilute nitric acid to a solution of the chrysammate, the pure 
 acid is precipitated in the form of golden-yellow scales 
 which are nearly insoluble in water, but impart to it a fine 
 purple colour. It is freely soluble in ether. According to 
 De la Rue and Miiller, chrysammic acid is also produced 
 by the action of nitric acid on chrysophannic acid. 
 
 The alkaline chrysammates are deep red, and crystallise 
 in plates having a golden-green metallic lustre, which are 
 sparingly soluble in cold water. The calcium, barium, and 
 magnesium salts are only very sparingly soluble in water, 
 but more readily in dilute alcohol. They all crystallise 
 well, especially the magnesium compound, which forms 
 large scales of a magnificent crimson colour. 
 
 Chrysammic acid, when treated with ammonia, yields 
 ammonium dirysamidate C 14 H 2 (X0 2 ) 4 3 (XH : . )XH,, crys- 
 tallising in dark red needles having a green iridescence. 
 Dilute acids remove the base from this salt leaving free 
 chrysamidic acid, C 14 H , (XO , ) , O 3 (X H 2 ) H. 
 
 Hydrochrysamide, C 14 H 10 N 4 O 6 ,or C U H 4 (NH 2 ) 3 (XO 2 )0 4 , 
 a substance crystallising in needles of a fine blue colour, 
 is readily produced from chrysammic acid by the action 
 of reducing agents, such as hydriodic acid, or zinc and 
 dilute sulphuric acid. It is insoluble in water, and only 
 sparingly soluble in boiling alcohol. 
 
 Boutin, Robiquet, and especially Saac and Schlum- 
 berger, have shown that from aloes, and its derivative chry- 
 sammic acid, a great variety of colours may be obtained, 
 including purples, pinks, orange, yellow, chocolate, brown, 
 olive, and grey, which dye both cotton, wool, and silk. 
 The shades given, however, vary considerably on the 
 different fabrics, even when the same mordant is applied; 
 as an instance of this, with an alumina mordant it gives a 
 pearl-grey on cotton, and a yellowish-brown on wool. 
 
 Turmeric or Indian Saffron. — This is the tuber or 
 underground stem of the Curcuma tinctcria, or longa, a 
 
TURMERIC— CURCUMIN. 285 
 
 plant which grows abundantly in the East Indies. It is 
 also imported from China, Java, Batavia, and Barbadoes, 
 but that shipped from Bombay is the most valued. 
 The roots externally are of a colour inclining to grey, but 
 internally of a deep yellow; they have an aromatic and 
 bitter flavour. 
 
 According to John their composition is as follows : — 
 
 Yellowish volatile oil 1 
 
 Yellowish-brown resin 10 to 1 1 
 
 Brown extractive matter, with dyeing properties 11 to 12 
 
 Gummy matter 14 
 
 Matter soluble in alkalis, including earthy salts. 57 
 Moisture, loss, &c 7 to 5 
 
 100 
 
 Turmeric is ground and sold to the dyers in the state of 
 a fine powder of a remarkably brilliant orange hue, and 
 having a strong odour. It only yields a small amount of 
 colouring matter to cold water; boiling water, however, 
 extracts a larger quantity, whilst alcohol dissolves the 
 colouring matter freely, and at the same time takes up 
 the greater part of the resin. 
 
 Vogel and Pelletier were the first to isolate the colouring 
 principle, and gave it the name of curcumin; but Lepage 
 afterwards devised a better process for extracting it. The 
 ground roots, after being treated with bisulphide of carbon 
 to remove the volatile oil and resinous matters, are ex- 
 tracted with a weak alkaline solution, which dissolves the 
 curcumin. The alkaline solution is then neutralised with 
 an acid, and the precipitated curcumin is collected, dried, 
 and crystallised from ether. In this state it forms small 
 brown scales, which yield on trituration a brilliant yellow 
 powder. The curcumin may also be extracted from the 
 root by benzene,* and the crystals purified by dissolving 
 
 * Daube. Deut. Chem. Ges. Ber., iii., 609. 
 
286 DYEING AND CALICO PRINTING. 
 
 them in spirit, precipitating with basic lead acetate, and 
 decomposing the lead compound with sulphuretted hydro- 
 gen. When recrystallised from boiling alcohol it is quite 
 pure, and then forms shining prisms, which are pale yellow 
 by transmitted, and red by reflected light. It is only 
 slightly soluble in water or benzene, even when boiling, but 
 is very readily soluble in alcohol and ether. It gives with 
 alkalis reddish-brown solutions, and is so easily affected by 
 mere traces of free alkali that paper prepared with it is 
 often used to detect their presence. Curcumin, C 10 H lu O 3 , 
 fuses without decomposition at 229° F. It is oxidised by 
 nitric acid with formation of oxalic acid. 
 
 It is well known to chemists, that when a piece of 
 turmeric paper is dipped into a solution of boracic acid, it 
 assumes a bright orange colour, which becomes red on the 
 addition of a strong mineral acid such as sulphuric or 
 hydrochloric. This red gradually becomes of a dark pur- 
 ple, especially if the paper be dried. If the same paper be 
 washed, and then dipped into alkaline solutions, it assumes 
 a brilliant blue colour which, however, soon disappears, 
 changing to grey. 
 
 Schlumbergcr,* who studied this reaction, has obtained 
 some very curious results. If an alcoholic solution of cur- 
 cumin is boiled with boracic acid, the solution becomes 
 orange, and when cold gives a bright vermilion-coloured 
 precipitate on the addition of water. This precipitate is 
 insoluble in ether and benzene, but is very soluble in 
 alcohol, to which it communicates an orange colour. This 
 compound is very unstable, it decomposes immediately if 
 the alcoholic solution is boiled, or even at ordinary tem- 
 peratures if kept some time, into boracic acid and a yellow 
 resin, pscudocuraimiti, which differs entirely from curcumin, 
 giving with alkalis a greenish-grey colour. The compound 
 produced from curcumin by boracic acid dissolves in alkalis 
 
 *Bull. Soc. Chim. [2.] v. 192. 
 
ROSOCYANIN. 287 
 
 with a purple-violet colour, which rapidly changes to a 
 dirty grey. 
 
 The most interesting substance, however, obtained by 
 Schlumberger is rosocyanin, the alcoholic solution of which 
 has a brilliant rose colour, similar to that of magenta, and 
 which changes to a rich dark blue on the addition of a 
 little ammonia or fixed alkali. It is prepared by treating 
 an alcoholic solution of curcumin with boracic and sulphuric 
 acids. The mixture rapidly acquires a deep red colour, 
 and the operation is completed when, on testing a small 
 quantity of the liquid, it becomes blue on the addition' of 
 ammonia. On allowing the solution to cool, the impure 
 rosocyanin crystallises out. When pure, it forms dark red 
 needles with a green iridescence, which are insoluble in 
 water, ether, and benzene. The intense rose colour of the 
 alcoholic solution is rapidly changed by heating, first to a 
 dark red, then orange, and finally yellow. The same change 
 takes place in the cold, but more slowly. Ammonia, 
 as already stated, changes the colour to dark blue, but 
 when the alkali is neutralised the original colour is restored. 
 The blue solution gives blue precipitates with lime and 
 baryta water, but if left in contact with the atmosphere it 
 rapidly becomes grey. 
 
 From these experiments it would appear probable that 
 curcumin is a glucoside which combines directly with 
 boracic acid, but which is decomposed by the action of 
 sulphuric acid. Schutzenberger remarks that rosocyanin 
 has a very great resemblance in its chemical properties to 
 cyanin, the colouring matter of flowers already noticed. 
 
 The Chinese dye silk with turmeric by merely dipping the 
 fabric in a decoction of the colouring matter acidulated 
 with citric acid; but although it gives colours with mor- 
 dants on cotton, silk, and wool, it is not employed as a 
 dyestuff in Europe on account of its fugitive character, 
 except as a constituent of certain compound colours, 
 
288 DYEING AND CALICO PRINTING. 
 
 especially those known as 'sour browns.' It is used, how- 
 ever, by paper stainers, and to dye wood and leather; also 
 for colouring pastry, butter, cheese, and pomades. It is an 
 important ingredient of the curry powder so largely used 
 in India in cookery. 
 
 Annatto. — This is the pulpy part of the seeds of the 
 Bixia orcllana, which grows in South America, and is im- 
 ported into this country from Mexico, Brazil, the Antilles, 
 and especially from Cayenne, in masses varying in weight 
 from 5 to 20 lbs., which are usually covered with banyan 
 leaves or reeds. It is also imported as a homogeneous 
 paste, in casks weighing 4 or 5 cwt. The paste has the 
 consistence of butter, and often has a repulsive odour of 
 urine, which, it is stated, is added by those who store it, to 
 keep it moist, and to impart to it a richer hue. 
 
 At Cayenne, when the fruit of the bixia is ripe, it is 
 gathered, coarsely crushed, and thrown into water, where it 
 remains for several weeks. By this means the pulpy matter 
 is separated from the kernel. It is next strained through 
 a coarse cloth, and the colouring matter gradually subsides. 
 It is then collected, and the excess of water evaporated 
 until it assumes a pasty state, when it is exposed to 
 the atmosphere, in the shade, until sufficiently dry to be 
 shipped. The powder so prepared, and especially at 
 Cayenne, is comparatively inferior, owing to the mass fer- 
 menting and producing matters which are injurious in the 
 dyeing process. The following analysis may be taken as 
 the average composition of such qualities of annatto : — 
 
 Water 72*25 
 
 Leaves 3-85 
 
 Starch, mucilage, woody fibre 1 8 '30 
 
 Colouring matter 5-60 
 
 IOO'OO 
 
AD ULTERA TION OF ANNA TTO. 289 
 
 Some forty years ago, M. du Montel introduced at 
 Cayenne some marked improvements in the manufacture 
 of annatto. Instead of crushing the seeds, he washed 
 them with water, so as to separate the colouring-matter, 
 and prevented the fermentation by the addition of some 
 chemical substance. By this means he obtained annatto 
 in a minute state of division, known as bixin, and having 
 a very beautiful red colour, which is imported into this 
 country in the form of small tablets, which are much used 
 for colouring cheese ; its dyeing power is, according to 
 Girardin, about three times greater than that of ordinary 
 annatto. 
 
 Annatto is only partially soluble in water, but is freely 
 so in ether and alcohol. Hydrochloric and acetic acids 
 have little or no action upon it, but it gives a blue colora- 
 tion with concentrated sulphuric acid which gradually 
 becomes green, and then violet. It dissolves readily in 
 alkalis and their carbonates, forming a dark red solution 
 in which acids produce an orange-red precipitate. 
 
 An alkaline solution of annatto gives an orange precipi- 
 tate with alum or sulphate of protoxide of iron ; a yellowish- 
 brown precipitate with salts of copper; and a lemon-coloured 
 precipitate with chloride of tin. 
 
 Common annatto, although sold at a comparatively low 
 price, is an expensive colouring matter, owing to the small 
 amount of colour-giving principle which it contains, even 
 when unadulterated. It is often, however, mixed with 
 ochre, and other coloured earths. To detect this fraud, it is 
 only necessary to dry it and calcine it, when, if pure, it will 
 not leave more than 8 to 12 per cent, of ash on the dried 
 annatto. The best process, however, to determine the 
 dyeing power, is to dye equal weights of cloth with a sam- 
 ple of the annatto to be tested, and with one of known good 
 quality. The bath should be composed as follows : — 
 
 U 
 
290 DYEIXG AXD CALICO PRINTING. 
 
 FOR COTTON. FOR SILK. 
 
 Annatto, dried at 212' F. ... 75 grains 7-5 
 
 Cream of tartar 150 „ 15-0 
 
 Water 6.000 .. 3.000 
 
 Two hundred grains of cotton yarn, and 30 grains of 
 boiled silk, are then weighed and immersed in their 
 respective baths, the whole boiled for fifteen minutes, and 
 left to cool for an hour. The dyed samples are then taken 
 out, squeezed, washed thoroughly, and dried in diffused 
 daylight, and the intensity and brilliancy of the two sam- 
 ples compared. The comparative value of two samples of 
 annatto may also be approximately determined by the 
 colorometer. To prepare the solutions for this purpose, 7 
 grains of each sample are digested in 700 grains of alcohol, 
 of 90 per cent, this liquid is then poured off, and the 
 operation repeated seven times. The intensity of colour of 
 the alcoholic extract from the two samples is compared. 
 
 The colouring matters of annatto have been studied by 
 Chevreul, Kerndt, Picard, Bolley, Mylius and Stein. It 
 contains two colouring matters, one of which, orcllin, is 
 yellow, soluble in water and alcohol but insoluble in ether; 
 it gives a yellow colour to cloth mordanted with alum. 
 Kerndt considers it to be a product of the oxidation or 
 decomposition of the second colouring principle, bixin, to 
 which Bolley assigns the formula C- H 6 0, ; Stein, however, 
 considers it to be C -H,.0.. Bolley and Mylius state that 
 neither Kerndt nor Picard obtained pure bixin, but a mix- 
 ture of that body with a resinous substance. To prepare 
 it, the best quality of annatto from Cayenne, after having 
 been washed and dried, is boiled with concentrated alcohol; 
 the alcoholic solution is evaporated to dryness, and placed 
 to digest with ether, which dissolves a part of the residue, 
 leaving a bright red powder, insoluble in water. This is 
 dissolved in alcohol, and an alcoholic solution of acetate of 
 lead added to it, when a red' lake is produced, which is 
 
USES OF ANNATTO. 291 
 
 washed with alcohol, suspended in water, and decomposed 
 by sulphuretted hydrogen. The red colouring matter is 
 removed from the lead sulphide by boiling it with alcohol, 
 which, on concentration, and the addition of water, yields a 
 red fioculent precipitate of bixin. When dried, it is a 
 Cinnabar red powder, insoluble in water or ether, but soluble 
 in alcohol and benzene. It is readily soluble in alkaline 
 solutions, and is coloured dark blue by concentrated sul- 
 phuric acid. 
 
 The use of annatto in print and dyeworks is rather 
 limited, being chiefly employed to modify the shades of 
 other dyes, such as certain tints of yellow produced by 
 fustic or quercitron. It is also used to give a bottom to 
 cotton before it is dyed with safflower or cochineal. In the 
 production of oranges in steam styles, annatto is now en- 
 tirely superseded by aurin, a colour derived from carbolic 
 acid. It is still often used in dyeing a low class of cotton 
 yarns ; the yarns being dipped in an alkaline solution of 
 annatto, and then passed through dilute sulphuric acid, 
 which precipitates the bixin in the fibre. It is then only 
 necessaiy to wash the cotton to complete the operation. 
 If an orange-yellow tint is required, the cotton is previously 
 mordanted with tin. 
 
 It is often employed to colour varnishes, cheese, and 
 butter. It is used also by the American Indians and Caribs 
 to dye their bodies. 
 
 Chica OR Carajara. — This is an orange-red colouring 
 matter obtained by the Indians from the leaves of the 
 Bignonia chica, which grows on the banks of the Rio Meta 
 and the Orinoco, and is employed by them, like annatto, 
 to dye their bodies. It is also used in the United States 
 to produce red and orange shades on cotton and wool, the 
 process followed being similar to that for annatto. 
 
 To prepare the colouring matter, the Indians boil the 
 leaves for some time in water, then throw the whole on a 
 
292 DYEING AND CALICO PRINTING. 
 
 strainer, and add some of the bark of a tree known as 
 'aryane', which causes a red floculent matter to be deposited 
 on standing. This is collected, made into cakes, and dried. 
 These cakes have an orange-red colour, are inodorous and 
 tasteless, and acquire a coppery lustre by friction. 
 
 The colouring principle is insoluble in water, but is solu- 
 ble in alcohol and ether, to which it imparts a fine ruby- 
 red colour. Acetic and hydrochloric acids dissolve it, 
 acquiring a reddish-brown tint, whilst with sulphuric acid it 
 gives an orange colour which changes to a dark purple on 
 the addition of ammonia. Caustic and carbonated alkalis, 
 and ammonia dissolve it, forming orange-red solutions, from 
 which it is again separated on the addition of an acid. 
 
 Erdmann has examined the colouring principle, to 
 which he assigns the formula C 8 H 8 3 . 
 
 Saffron. — Saffron, the stigmata of the flower of the 
 Crocus sativus is obtained from Austria, Spain, and France, 
 especially in the neighbourhood of Avignon. The stigmata 
 are gathered in October, and dried in the sun or over a 
 slow fire. It requires 100,000 stigmata to produce a pound 
 of saffron, which explains why it is such an expensive drug. 
 It has a rather agreeable odour, and a bitter, pungent taste. 
 It yields to water and alcohol, a yellow colouring matter 
 called saffronin, but which is now seldom used as a dye, 
 although formerly a favourite one. Saffronin, or crocin, 
 may be obtained as an inodorous pink powder, which be- 
 comes brown when heated, and is decomposed at 400 F. 
 It yields an orange-coloured solution with water, alcohol, 
 and the alkalis, but is nearly insoluble in ether. Con- 
 centrated sulphuric acid dissolves crocin, becoming first blue, 
 and then purple. Boiling with dilute sulphuric acid causes 
 it to split up into glucose, and a dark red amorphous body 
 called crocetin, having the formula C, H w O n . 
 
 BARBERRY Root. — This is the root of the Herberts 
 vulgaris, or common barberry, which grows in nearly 
 
BERBEREXE. 293 
 
 all parts of the world, but perhaps most luxuriantly in 
 India. 
 
 The colouring principle, berberine> was first isolated by 
 Buchner.* To prepare it, the root is exhausted with boiling 
 water, the extract concentrated by evaporation, and then 
 treated with hot alcohol ; after filtration the greater part of 
 the alcohol is distilled off, and the residue left to itself in 
 a cool place ; yellow crystals of berberine are then 
 deposited, and may be purified by recrystallisation, first 
 from water, and then from alcohol. 
 
 The best method of extracting the berberine*f" from those 
 sources, such as barberry bark and Colombo wood, which do 
 not contain much starch, is to boil them with water and a 
 slight excess of basic lead acetate, filter and concentrate 
 until the substance crystallises out on cooling. After the 
 crystals have been collected, the remainder of the alkaloid 
 is precipitated from the mother liquors as nitrate by the 
 addition of excess of nitric acid. The free base can be 
 obtained from the nitrate by heating its aqueous solution 
 with milk of lime. In order to purify the crude berberine, it 
 is dissolved in boiling water, basic acetate of lead added as 
 long as a precipitate is produced, the solution filtered, and 
 the excess of lead removed by means of sulphuretted hy- 
 drogen. On cooling, pure berberine crystallises out. 
 
 Berberine has also been found in Berberis aristata; in 
 JateorJiiza palmata or Coccuhis palmatus, the calumbo, 
 or Colombo root, by Bodeker;^: in the columbo wood 
 of Ceylon, Menispermum fenestration, by Perrins;§ by 
 Stenhouse]] in 'yellow bark', Coelocline polycarpa, used as 
 a dye by the natives of Abeocouta in West Africa ; 
 
 *Ann. Cliim. Pharm., xxiv., 22S. 
 
 tjour. Chim. Soc, xx., 187. 
 
 X Ann. Chim. Pharm., lxvi., 384, and lxix., 40. 
 
 § Ibid., lxxxiii., 276. 
 
 || Pharm. J. Trans., xiv., 455, 
 
294 DYEING AND CALICO PRINTING. 
 
 by Mayer* in podyphyllum root, Podophyllum peltatum, 
 and from the root of the Hydrastis canadensis. It forms 
 yellow silky needles which have a strong bitter taste. 
 It is only sparingly soluble in cold water or alcohol, but 
 freely so when boiling; it is insoluble in ether, but the 
 fixed and volatile oils dissolve it to a slight extent. 
 Berberine is an alkaloid of the formula C M H 17 N0 4| which 
 in alcoholic solution gives green lustrous scales, with solu- 
 tion of iodine or iodide of potassium. It combines with 
 acids, yielding well defined yellow-coloured salts, of which 
 the nitrate is remarkable for its insolubility in solutions 
 containing a slight excess of the acid; it is decomposed 
 by boiling nitric acid, yielding oxalic acid among other 
 products. Nascent hydrogen converts it into a colour- 
 less compound, hydroberberin, C^H^NO^. Barberry root 
 has been used alone to dye silk yellow, but alum and 
 salts of tin brighten the colour. Its chief use, however, 
 is for dyeing leather. 
 
 Gamboge. — This is a gum-resin, produced from the 
 Garcinia morella, a tree belonging to the order Guttifcra, 
 and growing in the peninsula of Camboga, in Siam, and in 
 the southern parts of Cochin China. A yellow juice flows 
 from incisions made in the trunk of the tree, which is col- 
 lected in bamboos, and allowed to thicken, when it forms 
 cylinders, often streaked with impressions from the inside of 
 the bamboo. This is the finest sort, called the pipe gamboge 
 of Siam. A portion is also formed into round cakes, either 
 entire, or having a hole in the middle. Gamboge is also 
 produced in Ceylon; and an inferior sort is said to be 
 obtained from the Gambogia gutta, a tree growing wild on 
 the Malabar coast. 
 
 Gamboge occurs in pieces of various sizes, of a dirty- 
 yellowish colour externally, and covered with a yellow 
 powder. When broken, it exhibits a vitreous orconchoi'dal 
 
 * Amer. Jour. Pharm., xxxv., 97. 
 
GAMBOGE. 295 
 
 fracture, with brown or saffron-yellow colour. Its powder 
 is of a brilliant yellow, and forms an emulsion with water. 
 Although it is nearly without odour at ordinary tem- 
 peratures, it gives out a very peculiar one when heated. 
 When taken into the mouth, it has at first scarcely any 
 perceptible taste, but after a time it causes a sharp, acrid 
 sensation in the throat. It is a drastic purgative. 
 
 Gamboge dissolves in alcohol, in ether, and in ammonia. 
 The ammoniacal solution forms a red precipitate with salts 
 of barium; yellow with zinc salts; reddish-yellow with 
 acetate of lead; and brownish-yellow with nitrate of silver. 
 
 The following analyses of gamboge are by Dr. Christison. 
 
 PIPE GAMBOGE, CAKE GAMBOGE, „„, T „..„,«„„ 
 
 FROM SIAM. FROM SIAM. CEYL ° N GAiIBOGE ' 
 
 Resin 74-2 71-6 64-3 65-0 6S8 71-5 72-9 75-5 
 
 Gum 2i - 8 24-0 207 197 207 188 19-4 18-4 
 
 Amylaceous ) 
 
 \ 6*2 
 
 matter J 
 
 Woody fibre 4'4 6 2 6-8 57 4-3 6 
 
 Moisture... 4'S 4-8 4-0 4-6 4-6 ... ... 4-8 
 
 5'o 
 
 ioo'S 100.4 99'6 ioo - 5 ioo - 9 96^0 966 99-3 
 The resin contained in gamboge is easily separated by 
 means of ether; it is hyacinth-red, and yields a powder of 
 a fine yellow colour. It possesses marked acid properties, 
 decomposing alkaline carbonates at the boiling heat, and 
 forming with the alkalis red salts, which may be separated 
 from their solutions by common salt, like soaps. Buchner 
 assigns to it the formula C- H 35 O 6 . 
 
 The purified resin, when fused with caustic potash, gives 
 off vapours having a pleasant aromatic odour, and the 
 residue is found to contain phloroglucin, pyrotartaric acid, 
 and two other acids, one of which is crystalline, and the 
 other not. The crystallised acid, which Hlasiwetz and 
 Barth * call isouvitic acid, C 9 H 8 O 4 , is isomeric with u vitic 
 
 *Ann. Chem. Pharm., cxxxviii., 61. 
 
296 DYEING AND CALICO PRINTING. 
 
 acid, and forms thick prismatic crystals, belonging to the 
 rhombic system. 
 
 The principal use of gamboge is as a pigment in water- 
 colour painting. An imitation gamboge is prepared from 
 turmeric. 
 
 ILIXANTHIN. — This is a yellow colouring-matter, first 
 observed by Nachtigal in the leaves of the Polygonum 
 fagopyrum, or common buckwheat, and afterwards investi- 
 gated by Schunck. It appears to be identical with the 
 ilixanthin which Moldenhauer* obtained from the leaves of 
 the holly Ilex aquifolium. It crystallises in pale yellow 
 needles, having the composition C 17 Ho 2 O n , and which are 
 only sparingly soluble in hot or cold water, but more 
 soluble in alcohol. Strong sulphuric acid changes its colour 
 to a deep yellow, without decomposition. It yields on 
 calico mordanted with alumina, a dark yellow colour; with 
 tin, a light yellow ; and with oxide of iron, various shades 
 of yellowish-brown, according to the strength of mordant 
 employed. 
 
 LICHENS. — Various yellow-coloured substances have been 
 obtained from the lichens, namely, clirysopJicuiic acid, and 
 valpic acid or chrysopicrin. Rochelder and Helt obtained 
 Chrysophaiiic acid (see rhubarb, p. 298) from the zcall lichen 
 or Parmelia parietina. 
 
 Vitlpic acid, or cJuysopicriu, was obtained by Moller and 
 Strecker, from the Cetraria vulpina, growing in Norway ; 
 by Bolley and Kinkelyn, from the Evernia vulpina of the 
 Alps ; and by Stein, from the Parmelia parietina. 
 
 Chrysinic acid, prepared by Picard from Poplar buds, 
 appears to bear a very close resemblance to vulpic acid. 
 
 To prepare these various yellow acids, the lichens are 
 macerated in an alkaline liquor, which is then separated 
 from the weed, and neutralised with an acid, when the 
 colouring principle separates. It is washed, and dissolved 
 
 Ann. Chem. Pharm., cii., 346. 
 
PURREE, OR INDIAN YELLOW. 297 
 
 in alcohol or ether, which, on evaporation, yields the acid 
 in a crystalline state. 
 
 Vulpicacid crystallises in needles of the formula C 10 H 14 O 5 , 
 which dissolve freely in water, alcohol, and ether. It 
 sublimes without decomposition at 250 F. and gives a 
 golden-yellow solution with alkalis, which is not changed by 
 exposure to the atmosphere. It produces a good yellow 
 colour as a dye. Chrysinic acid possesses very little 
 interest. 
 
 Purree, or Indian Yellow. — Purree, or Indian yellow, 
 is a colouring matter imported from India and China in 
 round lumps, weighing from 3 to 4 ozs., of a brown colour 
 externally, and of a bright yellow internally, and, according 
 to Erdmann, exhibiting a crystalline structure. Although, 
 when boiled in a solution Of borax, it yields a fine yellow 
 colour on silk and cotton prepared with alumina mordants, 
 it is not employed for that purpose, on account of its high 
 price. Its chief use is as a pigment in oil and water- 
 colour painting. 
 
 The origin of this substance is still a disputed question. 
 Some believe it to be an intestinal or biliary concretion 
 of the camel, the elephant, and the buffalo ; whilst 
 others think that it is a deposit from the urine of these 
 animals when they have been eating the leaves of cer- 
 tain plants, among which is the mango, or Mangostana 
 mangifer. 
 
 The colouring matter is magnesium euxanthate, from 
 which the enxcuithic acid is prepared by washing the purree 
 thoroughly with boiling water, and dissolving the residue 
 in boiling dilute hydrochloric acid, which, on cooling, de- 
 posits the euxanthic acid in tufts of yellow needles. It has 
 a sweet taste, and bitter after taste; and is freely soluble 
 in ether and alcohol, but only slightly so in water. Its 
 formula, when crystallised from alcohol, is C 21 H 18 O n + OH 2 , 
 but it loses the molecule of water when dried at 265 ° F, 
 
298 DYEING AND CALICO PRINTING. 
 
 If precipitated from its ammoniacal solution by hydrochloric 
 acid, it retains three molecules of water, C 21 H 18 O u + 30H 2 . 
 
 According to Stenhousc, if the anhydrous acid be 
 cautiously heated in a tube, it yields a yellow sublimate, to 
 which he has given the name cuxauthoiie, C, H 1;i O c . 
 
 Euxanthic acid forms well defined salts. Numerous 
 derivatives have also been obtained by the action of various 
 reagents, such as bromine, chlorine, nitric acid, &c, but they 
 are interesting only from a scientific point of view. 
 
 Indian yellow being somewhat costly, is often adulterated 
 with cheaper yellows, such as chromate of lead. This may 
 be detected by calcination, when the genuine yellow under- 
 goes slow combustion, leaving only a small amount of ash, 
 whilst if mineral matter has been added a larger per 
 centage will be found. 
 
 RHUBARB. — This drug, which is the root of various 
 species of RJicum, as R. palmatum, R. compactum, R. aus- 
 trale, &c, contains several definite chemical compounds, 
 the most important of which is chrysophanic acid. This is 
 best extracted from the root by exhausting it with cold 
 water, drying it, and boiling it with benzene. On concen- 
 trating the benzene solution by distillation, and allowing 
 the residue to cool, it solidifies to a crystalline mass of the 
 acid, which may readily be purified by treating it with a 
 dilute solution of soda, and recrystallisation. Chrysophanic 
 acid crystallises in pale yellow, six-sided plates, which 
 are almost insoluble in water, and but slightly soluble in 
 alcohol. It is not as yet definitely settled whether its 
 formula is C 14 H 10 O 4 , or C 14 H 8 4 . When boiled with 
 fuming nitric acid it is converted into chrysammic acid 
 (p. 283). Chrysophanic acid also exists in senna, in Runicx 
 obtusifolius, and many other species of this genus, and also 
 in Parmelia parietina, the yellow wall lichen. 
 
 RUTIN. — Rutin is a glucoside which appears to be widely 
 diffused in the vegetable kingdom. It was first obtained 
 
RUTIN.— SCOPARIN. 299 
 
 from garden rue by Weiss and Borntrager, afterwards from 
 capers by Rochleder and Hlasiwetz, and by Stein from 
 Wai'fa, the undeveloped flower buds of the Sopliora japonica. 
 It crystallises from its aqueous solution in pale yellow 
 crystals, to which the formula 2C 23 H 2S 15 , 5OH0 has been 
 assigned. It loses three molecules of water at 21 2° F., and 
 the remaining two at 320 F. It is nearly insoluble in cold 
 water, but freely soluble in boiling water, or hot alcohol ; 
 it is insoluble in ether, but soluble in acetic acid. 
 It dissolves freely in alkalis, and their carbonates ; and 
 also in lime, and baryta water, forming yellow solutions 
 from which acids precipitate the rutin unaltered. These 
 solutions become brown on exposure to the atmosphere. 
 
 Cold nitric acid at first imparts a yellow colour to rutin, 
 which quickly passes to an olive, and finally to a brown. 
 Boiling nitric acid converts it into oxalic and picric acids. 
 Boiled with dilute sulphuric acid, rutin is decomposed into 
 glucose and quercetin, as shown in the following equation : — 
 C 25 H 2S 15 + 3 OH 2 = C 13 H 10 O 6 + 2C 6 H 12 6 . 
 Rutin. Quercetin. Glucose. 
 
 When acted on by sodium-amalgam, rutin yields para- 
 carthamin. 
 
 SCOPARIN, C 21 H 22 O 10 . — This compound which was ob- 
 tained by Stenhouse from the Spartium scopariuiu, although 
 not a dyestuff, is considered by Hlasiwetz to belong to the 
 quercetin group, for when fused with caustic potash it is 
 split up into phloroglucin and protocatechuic acid, as repre- 
 sented in the following equation : — 
 
 C 21 H 22 O 10 +50 = QH 6 0, + 2C 7 H G 4 + C0 2 + 2 OH* 
 
 Scoparin. Phloroglucin. Protocate- 
 
 chuic acid. 
 
 Scoparin, when freed from chlorophyll and other im- 
 purities, is a pale yellow, brittle, amorphous mass, which 
 may, however, be obtained in small crystals by the sponta- 
 neous evaporation of its alcoholic solution. It is a neutral 
 compound, and is tasteless and inodorous : with alkalis 
 
3 oo DYEING AND CALICO PRINTING. 
 
 and their carbonates, or with ammonia, it gives yellowish- 
 green solutions. The ammoniacal solution leaves on 
 evaporation a green jelly, which, when dry, is free from 
 ammonia, and has the same composition as the crystallised 
 body. Scoparin, in fact, readily assumes either the colloid, 
 or the crystalline form. 
 
 Taigu, OR Tayegu Wood. — M. J. Arnaudon,* some 
 years ago, on examining with a microscope a sample of 
 Taigu wood imported from Paraguay, observed some yellow 
 prismatic crystals, which proved to be a colouring matter. 
 To extract it, the wood is cut into small pieces and treated 
 at the ordinary temperature with alcohol of "844, which 
 dissolves the colouring principle together with a little 
 reddish-brown resin. This alcoholic solution, when concen- 
 trated, yields crystals of the impure colouring matter, which 
 may be purified by recrystallisation, first from alcohol, and 
 afterwards by the spontaneous evaporation of the ethereal 
 solution. The new substance, taiguic acid, forms golden- 
 yellow prisms, which are not altered by exposure to the air 
 if light be excluded, but in sunlight it becomes orange- 
 coloured, and finally brown. It melts without decomposi- 
 tion at 275° R, and sublimes at 356° F., yielding large 
 prismatic crystals. As already noticed it is soluble in 
 alcohol and ether, but insoluble in water. It dissolves also 
 in wood spirit and bisulphide of carbon. It is soluble in 
 alkaline solutions with intense scarlet colour, so that it 
 forms a very delicate test for the presence of free alkali. 
 If a small quantity of taiguic acid be added to water con- 
 taining a millionth part of free ammonia, a distinct colora- 
 tion is perceptible. 
 
 A decoction of taigu wood made with alkaline carbonates 
 imparts a fine orange-red colour to cotton, dipped first into 
 the solution, and then into a bath of dilute acid. The dye 
 is very similar in shade to that obtained with annatto. 
 * Technologiste, xix., 453. 
 
LO-KAO, OR CHINESE GREEN. 30 1 
 
 WONGSHY, OR Hoang-tchy. — Rondot, Persoz, and 
 
 Martius, have examined four yellow colouring matters 
 
 employed in China, but of these only one, called Wongshy, 
 
 or hoang-tcJiy, and which is the fruit of the Gardenia grandi- 
 
 fiora, appears to possess any peculiar interest. 
 
 The colouring principle has been studied by Stein, Orth, 
 Rochleder, and Martius, and according to Rochleder is 
 identical with crocin, the colouring matter of saffron. 
 
 Carotin. — The yellow colouring matters of carrots, 
 gentian root, and several other plants have been studied, 
 but present no special interest as they have received no 
 applications. 
 
 Rottlera. — The fruit of the Rottleva tinctoria is used 
 in India for dyeing silk an orange colour. It contains a 
 principle, rottlerin, having the formula C n H 10 O 3 , which 
 crystallises in yellow silky needles; they are insoluble in 
 water, but moderately soluble in ether and in boiling 
 alcohol. 
 
 GREEN COLOURING MATTERS. 
 
 Lo-kao, or Chinese Green. — In 1848, attention was 
 drawn by several English gentlemen to samples of a green 
 colouring matter coming from China, which in the mean 
 time was studied in France by Kcechlin, Schouch, and 
 Persoz. In 1853, MM. Guinon, Manias, and Co., of Lyons, 
 imported it in sufficient quantity to enable them to dye 
 silk for the requirements of trade. The silks so dyed were 
 known by the names of Vert-venus, Vert-azof, Vert-lumiere, 
 and were specially admired from their retaining their green 
 colour when seen by artificial light. We are indebted to 
 the kindness of Messrs. Guinon, Marnas, and Co., of Lyons, 
 for the accompanying specimen of the effect obtained on 
 silk with lo-kao. 
 
302 D YEING AND CALICO PRINTING. 
 
 L0-KA0. 
 
 The use of this colour was, however, discontinued, as it 
 was not very fast, and Messrs. Guinon, Marnas, and Co., 
 found that they could produce greens possessing the 
 same property by first dyeing their silks with Prus- 
 sian blue, and then in an acidulated bath of picric 
 acid. It is interesting to observe that if indigo be 
 substituted for Prussian blue, the colour appears blue by 
 artificial light. This process has since been superseded by 
 the beautiful aniline greens. 
 
 M. Charvin, of Lyons, received a gold medal from the 
 Chamber of Commerce of Lyons, for the discovery of a 
 process for preparing lo-kao from a plant indigenous to 
 Europe — the Rhamnus catharticus, or buckthorn. 
 
 According to Persoz, the lo-kao imported into this country 
 had three shades of a dark greenish blue, and had the fol- 
 lowing composition : — 
 
 Colouring matter 6 1 "90 
 
 Mineral matter, chiefly lime 28 - 8o 
 
 Water 9-30 
 
 IOO'OO 
 
 It is insoluble in alcohol, ether ,and bisulphide of car- 
 bon, and only partially soluble in water. The addition of 
 an acid increases its solubility. The alkalis dissolve out 
 of it a green colouring matter, and the solution becomes 
 brown on being boiled, or even if kept for some time at 
 ordinary temperatures. 
 Reducing agents such as arsenious, hyposulphurous, oxalic, 
 
LOKAIN. 303 
 
 and formic acids, give rise to a violet-purple precipitate 
 with lo-kao, whilst sulphuretted hydrogen imparts to it a 
 blood-red coloration. Exposure to the atmosphere restores 
 after a time the green colour. Protochloride of tin dissolves 
 it partially with an intense red coloration, which changes 
 to green on the addition of an alkali and exposure to 
 the air. Oxidising agents, such as nitric and chromic 
 acids, also convert the green colour into a red one; but in 
 this case the green colour is not restored by exposure to 
 the air. Certain salts, such as those of magnesia and zinc, 
 change the green colour to blue. Cloez and Guignet have 
 recently published a paper on this interesting substance, in 
 which they state that if lo-kao is mixed with water, and left 
 in a warm place for several days, it ferments and becomes 
 partially reduced. If it be now washed with cold water 
 and then boiled in that menstruum, a reddish-violet coloured 
 solution is obtained, which gives a blue precipitate when 
 exposed to the atmosphere. This compound they, in 
 common with Persoz, consider to be the true colouring- 
 principle of lo-kao, and have named it loka'in. It may be 
 prepared in larger quantities by agitating the lo-kao with 
 a solution of carbonate of ammonia, filtering, and pre- 
 cipitating with alcohol. 
 
 To obtain pure lokain, one part of pure carbonate of 
 ammonia is dissolved in forty parts of water, and one part 
 of roughly powdered lo-kao added, the mixture being 
 shaken from time to time for about four days, when the 
 liquor assumes a very dark greenish-blue colour. The solu- 
 tion thus obtained is filtered and evaporated to dryness in 
 a water bath, to drive off the excess of ammonium car- 
 bonate. The residue, which is soluble in water, is a com- 
 bination of lokain with ammonia, and is further purified by 
 dissolving it in water and precipitation with alcohol. On 
 analysis it yields numbers corresponding to the formula 
 Co 8 H 33 17 ,NH 4 . This compound, on being kept at a tern- 
 
304 DYEING AND CALICO PRINTING. 
 
 perature of 21 2° F. for several hours, is decomposed, and 
 yields ammonium lokaetin, an insoluble violet-coloured 
 substance. The same substance is produced when lo-kao is 
 fermented with the addition of yeast : the solution assumes 
 an intense red colour, and on filtration and exposure to 
 the air a rich purple precipitate is thrown down, which is 
 ammonium lokaetin. 
 
 By the action of sulphuric acid the solution of ammonium 
 lokai'n is decomposed into glucose and an insoluble 
 substance lokaetin, to which the formula C 9 H 8 O 10 has 
 been assigned. Lokai'n is therefore a glucoside. 
 
 Lokaetin assumes a most intense purple in the presence 
 of the slightest trace of alkali. With sulphide of ammonium 
 it gives a red floculent precipitate. Nitric acid transforms 
 it into oxalic acid and a new yellow colouring matter. 
 
 From the various colours which lokai'n gives under the 
 influence of certain chemical reagents, and from its being 
 prepared from a species of Rhamnus, it was the author's 
 opinion that there existed a very close analogy between this 
 compound and some of the derivatives of rhamnetin, if not 
 an absolute identity. In all probability, therefore, there 
 must be an intimate relation between it and quercetin, and 
 especially the rosocyanin obtained from turmeric. 
 
 The solution obtained by digesting lo-kao with water,, 
 dyes silks a pale bluish-grey similar to that observed on 
 some Chinese silks. Ammonium lokaetin alone, dyes cotton, 
 silk, and wool of a violet colour, no mordant being required. 
 If employed in a bath of hyposulphite of soda, it dyes 
 cotton a fast bright sky-blue, which is permanent when 
 exposed to light. 
 
 YVaifa. — There have been several other green colouring 
 matters sent from China to Europe, but with the exception 
 of waifa, they have no special interest, their composition 
 and mode of application being unknown. 
 
 Waifa is the undeveloped flower-buds of the SopJiora 
 
SAP GREEN. 305 
 
 japonica, which grows abundantly in the southern parts of 
 China, and in India. Stein extracted from it a yellow colour- 
 ing principle, which he considers to be identical with rutin. 
 
 To obtain a green colour, the Chinese dip the cotton to 
 be dyed into a boiling solution of waifa, to which a small 
 quantity of alum has been added, and then expose the 
 fabric to the sun's rays. These operations are repeated 
 until the required depth of shade is obtained. 
 
 Sap Green. — There has for many years been a green 
 in use prepared from the Rhanmus catJiarticus, or buck- 
 thorn, and known by the name of sap, or bladder green. 
 It is employed by paper stainers and leather dyers, and is 
 largely manufactured in the neighbourhood of Neuremberg. 
 The ripe berries "are submitted to pressure, when a purple- 
 red juice is obtained, which becomes green on the addition 
 of an alkali. To produce the colour, a little soda or lime is 
 added, together with a small quantity of alum and gum. 
 The liquid is then concentrated to the state of a thick 
 syrup, and filled into pig bladders; it is from this circum- 
 stance that it derives its name of 'bladder green.' 
 
 CHLOROPHYLL. — Notwithstanding the numerous re- 
 searches which have been made by some of the most 
 distinguished chemists on the green colouring matter of 
 leaves, we are still far from having a correct knowledge of 
 its composition and properties. The great difficulties at- 
 tendant on the investigation of this subject, are owing, not 
 only to the green colouring principle being associated with 
 various other substances of a waxy or fatty nature, but 
 also to the readiness with which chlorophyll becomes 
 altered by the action of chemical agency, and even by 
 exposure to light. 
 
 It may be obtained by the following process : — green 
 
 leaves are digested several days with ether, and the filtered 
 
 liquid evaporated to dryness. The residue is treated with 
 
 boiling alcohol, and a small quantity of milk of lime added 
 
 V 
 
3o6 DYEIXG AXD CALICO PRINTING. 
 
 to the solution, which precipitates all the colouring matter, 
 whilst the alcohol retains a quantity of the fat which was 
 mixed with it. The chlorophyll is separated from the lime 
 by means of hydrochloric acid, and ether is then added to 
 dissolve the colouring matter, which forms a green stratum 
 at the top of the liquid. 
 
 The chlorophyll is obtained on evaporating the ethereal 
 solution, but not in a pure state, as it is still contaminated 
 by a certain amount of fatty matter. 
 
 Hartsenn* mixes finely chopped ivy leaves with spirit of 
 wine of 55", and after allowing them to stand twelve hours, 
 presses them : this removes the water, a bitter substance 
 called helicin, and a saponifiable compound. The pressed 
 leaves are now soaked in benzene for twenty-four hours, and 
 the benzene is removed from the expressed solution by 
 distillation. The dark-brown fatty residue, amounting to 
 2^ per cent, of the leaves, is treated with a solution of 
 soda, filtered, and precipitated by common salt. The pre- 
 cipitate, after being washed with a salt solution, is dissolved 
 in water, and precipitated with a solution of copper sulphate. 
 This precipitate, after being washed and dried, is boiled 
 with absolute alcohol, and then washed with ether and 
 benzene ; this treatment removes the copper soap, and 
 leaves the compound of chlorophyll with copper oxide. 
 On suspending the latter in alcohol, and decomposing it 
 with sulphuretted hydrogen, a solution is obtained, which 
 leaves pure chlorophyll on evaporation. 
 
 Chlorophyll, thus prepared, is quite free from fatty mat- 
 ter, and is an earthy powder of a very deep green colour, 
 almost black, unalterable in the air, infusible, sustaining a 
 heat of 390" F. without decomposition, but decomposing 
 at higher temperatures. It is insoluble in water, even at 
 the boiling heat, but is easily soluble in hydrochloric acid, 
 and in alcohol ; less so in ether. 
 
 * Chem. Centr. 1873, 2 °4- 
 
CHLOROPHYLL. 
 
 307 
 
 Among those chemists who have studied the green colour- 
 ing matters of leaves, M. Fremy* is of opinion that the green 
 colour is composed of two substances, a yellow and a blue ; 
 to the former of which he gives the name phylloxanthin, 
 and to the latter phyllocyanin. If dried green leaves, 
 or the alcoholic extract from leaves, be agitated with a 
 mixture of ether and dilute hydrochloric acid, and allowed 
 to stand, the liquid separates into two layers ; the superna- 
 tant ethereal one having a yellow colour, whilst the hydro- 
 chloric acid solution has a blue colour. Again, on mixing 
 an alcoholic extract of the leaves with gelatinous alumina, 
 and then carefully adding water, a bright blue lake is pre- 
 cipitated, whilst the solution has a bright yellow colour. 
 If the solution be now filtered, a fresh quantity of hydrate 
 of alumina added, and then a large quantity of water, a 
 yellow precipitate is produced. The lakes thus obtained 
 may be collected, washed, and dried, and if then treated 
 with alcohol, yield to that solvent their respective colours. 
 
 Fremy also observed that young and sickly leaves, when 
 exposed to the vapours of hydrochloric acid, assumed a 
 bright green tint, the yellow colouring matter existing in 
 larger quantity than in normal leaves. In the autumn 
 leaves, however, he could find no trace of phyllocyanin, 
 phylloxanthin only being present ; the latter is therefore a 
 more stable compound than the former. 
 
 Phylloxanthin^ is a neutral substance, insoluble in water, 
 soluble in alcohol and ether, and crystallising therefrom in 
 yellow laminae, or red prisms, resembling those of potassium 
 bichromate. It possesses very great colouring power, and 
 dissolves with blue colour in strong sulphuric acid, whereas 
 the yellow colouring matter of flowers becomes red under 
 similar circumstances. 
 
 Phyllocyanin is insoluble in water, but dissolves with 
 
 *Compt. Rend., 1., 405. 
 t Fremy, Ann. Chim. Phys., [4] vii., 78. Ludwig, Arch. Pharm., [2] cvi., 164. 
 
308 DYEING AND CALICO PRINTING. 
 
 olive-green or bronze-red colour in alcohol and ether ; its 
 salts are brown and green ; those of the alkali-metals are 
 yellow, and soluble in water. The solutions of phyllo- 
 cyanin in sulphuric or hydrochloric acid are green, reddish- 
 violet, or blue, according to the degree of concentration; 
 the phyllocyanin being precipitated from them on the 
 addition of water. Alkalis change its colour to bright 
 yellow, but it again becomes green, if it be dissolved in 
 alcohol and hydrochloric acid added. 
 
 Professor Stokes * concludes from the optical characters 
 of chlorophyll, that it is# mixture of four different colouring 
 matters, two of which are yellow, and two green. The 
 solutions of the green (but not of the yellow) colouring 
 matters exhibit strong red fluorescence ; three of these 
 substances are very easily decomposed by acids or acid 
 salts, binoxalate of potash for example. Fremy's phyllo- 
 cyanin is, according to Stokes, merely a product of decom- 
 position of the green bodies by acids; it is soluble in most 
 acids, yielding green or blue solutions. Neutral solutions 
 exhibit very sharp absorption bands. Phylloxanthin varies 
 in its properties according to the manner in which it has 
 been obtained. If the green substances have been removed 
 by means of hydrate of alumina, it is one of the yellow sub- 
 stances existing in the plant; if, however, acids have been 
 used in its preparation, it consists of the same yellow sub- 
 stance, contaminated, however, with the products of the 
 decomposition of the green substance. 
 
 According to Filhol,-f- all the methods of preparing 
 chlorophyll in which acids are used, yield nothing but 
 products of decomposition. By cautious treatment, four 
 substances may be obtained, namely : a yellow compound, 
 soluble in alcohol, which is resolved, by treatment with 
 strong hydrochloric acid, into a blue soluble substance and 
 
 * Proc. Roy. Soc, xiii., 144. 
 fAnn. Chim. Phys., [4] xiv. Compt. Rend., Ivi., 1218, and lxi., 371. 
 
CHLOROPHYLL. 309 
 
 a yellow precipitate. On adding oxalic acid to an alcoholic 
 solution of chlorophyll, a brown body is separated : this is 
 soluble in alkaline solutions with an orange-red colour, 
 which, on exposure to the air, becomes pure green from 
 absorption of oxygen. 
 
 LommeL* who has lately published a paper on the op- 
 tical properties of chlorophyll, states, that the dark 
 absorption bands observed in a solution of chlorophyll in 
 dilute alcohol, when examined with the spectroscope, cor- 
 respond, both in position and brightness, with the bright 
 fluorescent bands produced in the same solution. The 
 spectrum of chlorophyll, both when fresh, and after it has 
 become modified by the action of light, has been investi- 
 gated by Gerland,-f- and by Chautard. % 
 
 Occasionally, dead trees contains a bright green colour- 
 ing matter which differs from chlorophyll. It is soluble in 
 chloroform, and is called xylocJiloeric acid. 
 
 M. Hartmann has succeeded in preparing a pigment 
 from chlorophyll, which, when properly thickened and 
 mixed with lime water, may be printed and steamed in the 
 usual way, yielding colours which are fast, although not 
 bright. The pigment is extracted from grass, which has 
 previously been washed with warm, very dilute lye, by 
 steeping it for twenty-four hours in a solution containing 
 7^ per cent, of caustic soda. On neutralising the deeply 
 coloured solution with hydrochloric acid, a green floculent 
 precipitate is produced, which only requires to be collected 
 on a filter and washed, in order to be ready for use. 
 
 * Pogg Ann. cxliii., 568. 
 + Pogg Ann. cxliii., 585. 
 % Compt. Rend. Ixxv., 1837, and lxxvi., 570* 
 
CHAPTER X. 
 
 TANNIN MATTERS. 
 
 There are certain principles widely distributed over the 
 vegetable kingdom which have an astringent taste, and 
 possess the property of giving a blue, or green coloration 
 or precipitate with persalts of iron. These astringent sub- 
 stances, or tannins, as they are called, when added to solu- 
 tions of gelatin or albumen, produce a precipitate which is 
 a compound of the animal substance with the tannin. All 
 these compounds resist putrefaction in a remarkable degree ; 
 those obtained with gelatin forming the basis of leather. 
 It has been known from time immemorial that the skins 
 of animals, and other animal membranes, when steeped for 
 a certain length of time in solutions of these astringent 
 matters, undergo a change by which they are rendered less 
 liable to putrefaction, and available for many purposes of 
 civilised life. The process by which this is effected is called 
 tanning, and those matters which have been found to con- 
 tain such a proportion of the principles as to be applicable 
 for this purpose have received the name of tannin matters. 
 The tannin is contained in various parts of plants ; in 
 some cases it is the bark, in others the fruit, whilst in others 
 again it is certain excrescences produced by insects. 
 
 The production of leather is not, however, the only use 
 to which these principles have been applied, for they give 
 colorations with certain metallic oxides, and have, con- 
 sequently, long been among the most valuable dyestuffs, 
 being employed chiefly for the production of blacks, greys, 
 and browns. 
 
TANNIC ACID. 311 
 
 Tannin matters, or the commercial articles used for dye- 
 ing, being the bark, leaves, &c, of plants, invariably con- 
 tain, besides the tannins peculiar to them, a certain amount 
 of extraneous matter, such as gum, and woody fibre. 
 
 The tannins, or thoseprinciples which are the true dyestufifs, 
 may be divided broadly into two classes, those which give a 
 blue-black precipitate with persalts of iron, such as gall- 
 nuts, Chinese galls, oak bark, sumach, dividivi, myrobalans, 
 and valonia ; and those which give a green coloration with 
 persalts of iron, such as catechu, gambier, gum-kino, and 
 elder, larch, and willow barks. Stenhouse has shown that 
 most of the natural tannins which give a blue precipitate 
 with persalts of iron are glucosides, whilst those which give a 
 green one are not glucosides, with the exception, perhaps 
 of the tannin of willow bark. 
 
 All the tannins are remarkable for the avidity with 
 which they absorb oxygen in presence of the alkalis, 
 becoming converted into bodies of various colours, green, 
 red, brown, and black. 
 
 Tannic, or Gallotannic Acid. — This, the most 
 important of the tannins, which gives a blue-black with 
 ferric salts, was first obtained by Prout in 1795. The best 
 method of preparing it in a pure state, however, is that 
 devised by Pelouze, who treated coarsely ground gall-nuts, 
 in a displacement apparatus, with ether, which had been 
 previously saturated with water, by being well skaken up 
 with it. The ethereal solution which percolates through 
 the gall-nuts separates into two layers, of which the upper 
 one is ether, containing colouring matter, gallic acid, and 
 other impurities ; whilst the lower is a syrupy, aqueous 
 solution of nearly pure tannin. This only requires to be 
 carefully evaporated in vacuo, or at a low temperature, 
 in order to obtain the tannic acid as a pale yellow, 
 amorphous, spongy mass, inodorous, and having a most 
 astringent taste. By this process one hundred parts 
 
312 DYEING AND CALICO PRINTING. 
 
 of good gall-nuts yield about sixty parts of tannin. Instead 
 of aqueous ether, a mixture of dry ether with 5 per 
 cent, of alcohol is very frequently used. 
 
 Tannin, as prepared by those methods, is almost insoluble 
 in ether, but readily soluble in alcohol, and in water. It is 
 precipitated from its aqueous solution by many of the 
 stronger acids, and also by various salts, such as common 
 salt, salammoniac, and potassium acetate. When boiled 
 with baryta water, it yields barium gallate and glucate. 
 Baryta or lime water in excess quickly colours tannin 
 green, then blue, red, and finally a yellowish-brown. It 
 gives a white precipitate with tartar emetic, or salts of 
 lead; a characteristic blue-black one with persalts of iron, 
 but none with the protosalts. It also gives precipitates 
 with gelatin, and with the vegetable alkaloids. When treated 
 with chromic acid, tannic acid is decomposed with evolu- 
 tion of carbonic anhydride ; whilst with bichromate of 
 potash it gives a yellowish-brown precipitate, which quickly 
 turns black. It begins to decompose at about 400 R, 
 carbonic anhydride being given off, whilst pyrogallic acid 
 sublimes, and a black compound, called metagallic acid, 
 remains in the retort. According to Strecker, the de- 
 composition takes place in the following manner : — 
 C^A; = 3C 6 H 6 3 + C 6 H 4 2 + 3 C0 2 . 
 
 Tannin. Pyrogallic Metagallic 
 
 acid. acid. 
 
 As tannin obtained by the methods above described 
 
 yields gallic acid and glucose when boiled with dilute acids, 
 
 it was for a long time considered to be a glucoside of gallic 
 
 acid, notwithstanding that the amount of glucose present in 
 
 different specimens of tannin varied greatly. The recent 
 
 researches of Schiff,* however, have thrown much light on 
 
 the subject, for by heating crystallised gallic acid with 
 
 phosphorus oxychloride for several hours, he succeeded in 
 
 *Ann. Chem. Pharm., clxx., 43, and clxxv., 165. 
 
GALLIC ACID. 313 
 
 obtaining a substance possessing all the physical and 
 chemical properties of ordinary tannin, but differing from 
 it in being perfectly free from glucose. When boiled with 
 dilute acids it is entirely converted into pure gallic acid, 
 which may again be reconverted into tannin. From an 
 examination of the acetyl derivatives of tannin, he came to 
 the conclusion that it is an etherated anhydride of digallic 
 acid, having the formula C u H 10 O 9 , which is that originally 
 assigned to it by Mulder. In a similar manner gallic acid 
 is almost entirely converted into tannin by heating its con- 
 centrated aqueous solution with arsenic acid. 
 
 Although glucose is almost invariably present in natural 
 tannin, yet it does not appear to be in the free state, that 
 is, it is not a mere mechanical mixture of pure tannin 
 and glucose. Schiff proposes to distinguish the natural 
 product, containing glucose, as tannin ; whilst the pure sub- 
 stance, free from glucose, may be called digallic acid. 
 
 In presence of alkalis, tannin absorbs oxygen from 
 the atmosphere, and is converted into a red substance 
 called tannoxylic or rufitannic acid. This acid, which has 
 the formula C 7 H G 6 , may be prepared as follows :— a mo- 
 derately strong solution of potash is saturated in the cold 
 with tannic acid, and the solution, which soon turns red, is 
 left to stand for some days until it becomes dark red and 
 nearly opaque. It is then precipitated with acetate of 
 lead; the resulting brick-red precipitate is treated with hot 
 acetic acid, to dissolve undecomposed tannate of lead, and 
 the tannoxylate of lead, which remains as a red precipitate, 
 is decomposed by heating with alcohol and sulphuric acid. 
 A dark red solution of tannoxylic acid is thereby obtained, 
 which on evaporation leaves the acid as a brown-red 
 amorphous substance. 
 
 Gallic Acid. — This acid, which was discovered by 
 Scheele, exists ready formed in several of the tannin mat- 
 ters, such as gall-nuts, sumach, valonia, dividivi, tea, &c, 
 
3 i4 DYEIXG AND CALICO PRIXTIXG. 
 
 but is usually prepared by the transformation of the gallo- 
 tannic acid of gall-nuts; for this purpose two processes are 
 generally employed. 
 
 The first consists in reducing gall-nuts to a coarse pow- 
 der, mixing it with water, and allowing it to stand for some 
 weeks in a dark place, the temperature being maintained 
 at from 70" to So : F. A green mould forms on the surface 
 soon after the fermentation sets in, and when it is complete 
 the tannic acid will be found to be converted into gallic 
 acid, mixed, however, with a small quantity of ellagic acid. 
 
 The second process, which is much more rapid, is based 
 on the fact that the action of the stronger acids on tannin 
 converts it into gallic acid. A strong decoction of gall- 
 nuts is treated with strong sulphuric acid, when a pasty 
 mass is thrown down, which is collected, washed 
 with dilute acid, and pressed. It is then boiled for 
 a few minutes with seven or eight times its weight 
 of dilute sulphuric acid (one part of acid to ten of 
 water), and allowed to cool, when impure gallic acid 
 crystallises out. It may be purified by recrystallisa- 
 tion, or still better, by conversion into gallate of lead, 
 which is washed, and decomposed by sulphuretted hydro- 
 gen. The sulphide of lead which is formed carries down 
 and retains the colouring matters, whilst pure gallic acid 
 remains in solution, and may be obtained on evaporation. 
 
 Gallic acid, C : H . ; O 5 , forms white silk}' needles, which are 
 sparingly soluble in cold water, but freely soluble in boiling 
 water, alcohol, and ether. It has no odour, but an astrin- 
 gent, slightly acid taste. It gives no precipitate with proto- 
 salts of iron, but a deep purple-blue with ferric salts. The 
 author observed some years ago, that if this precipitate were 
 kept for a few days it would be redissolved, the gallic acid 
 reducing the peroxide of iron to the state of protoxide. 
 Unlike tannin, it gives no precipitate with gelatin or 
 albumen, which is a most important fact, as will be seen 
 
REACTIONS OF GALLIC ACID. 315 
 
 when we consider the application of tannin matters to 
 dyeing and the preparation of leather. 
 
 With lime and baryta water, gallic acid gives a character- 
 istic precipitate, white at first, but soon becoming green on 
 contact with the air, and finally brownish-red. This 
 affinity of the acid for oxygen in the presence of alkalis is 
 far more active than that of tannin, as was shown by 
 Chevreul in 1820, in his researches on the oxidation of 
 colouring matters under the influence of alkalis. He sug- 
 gested that tannin, or gallic acid might be used with advan- 
 tage for the determination of the quantity of oxygen in 
 gaseous mixtures. In 1838, Liebig again called attention to 
 this property of gallic acid, and proposed the use of it, or 
 still better, pyrogallic acid in gas analysis. The process, how- 
 ever, is not perfectly accurate, for in 1863, the author showed 
 that a small portion of the oxygen is converted into car- 
 bonic oxide, the volume of that gas amounting to 3 or 4 per 
 cent, of that of the oxygen absorbed when the gas operated 
 on was pure oxygen, and about 25^ per cent, with air. 
 
 Gallic acid reduces the salts of gold and silver to the 
 metallic state. It is a tribasic acid which expels carbonic 
 acid from its salts, and forms three series of salts, contain- 
 ing one, two, and three equivalents of the base. Perman- 
 ganate of potash decomposes gallic acid, oxidising it to 
 carbonic acid and water. A volumetric method for the 
 determination of gallic acid has been based on this reaction 
 by Morin. 
 
 When gallic acid, or pure digallic acid, is heated with 
 concentrated sulphuric acid, it loses the elements of water, 
 and becomes converted into a red-coloured compound, rufi- 
 gallic acid, C u H 8 8 . On adding water to the mixture, the 
 acid is thrown down as a red crystalline precipitate. It is 
 only very slightly soluble in water, but it dissolves in alka- 
 line solutions with a violet colour. It dyes mordanted 
 cloth like alizarin, but the colours are dull. 
 
316 DYEING AND CALICO PRINTING. 
 
 When submitted to a temperature of 21 2° F., gallic acid 
 loses two equivalents of water, and on being heated to 
 about 410 F., it splits up into carbonic anhydride, and a 
 beautiful white crystalline compound, called pyrogallic 
 acid or pyrogallol, according to the following equation : — 
 C 7 H 6 5 - C 6 H 8 3 + C0 2 . 
 
 Gallic acid. Pyrogallol. 
 
 At a higher temperature metagallic acid is also formed. 
 
 Gallic acid has been produced synthetically by treating 
 di-iodosalicylic acid with a hot concentrated solution of 
 potassium hydrate, the reaction being as follows: — 
 C 7 H 4 I 2 3 + 2KHO - C 7 H 6 6 + 2KI. 
 
 Iodosalicylic Gallic acid, 
 
 acid. 
 
 Pyrogallic Acid or Pyrogallol. — This compound 
 has acquired considerable importance of late years from 
 the extensive use which has been made of it as a reducing 
 agent in photography, and also from its application to 
 reduce the metallic salts used with hair dyes. It was first 
 observed by Scheele as a white sublimate, obtained on 
 heating gallic acid. He, however, considered it to be 
 sublimed gallic acid, and it is to Berzelius and Pelouze 
 that we are indebted for establishing its composition. 
 
 The following process for obtaining pyrogallic acid 
 commercially, was published by Stenhouse in 1843. 
 Powdered gall-nuts are exhausted with water and the 
 solution evaporated to dryness : the extract thus obtained, 
 is reduced to powder and placed in a thin iron vessel 
 having a flat bottom, on the top of which a perforated 
 sheet of blotting paper is pasted, and over this a cardboard 
 cone. A gentle heat is then applied, and gradually in- 
 creased, until white vapours begin to escape from the top 
 of the cone. As soon as the vapours cease to be given off, 
 the cone is removed, when the pyrogallic acid is found on 
 the surface of the blotting paper, and lining the interior 
 of the cone. If the operation is carefully conducted the 
 
PYROGALLOL. 317 
 
 gall-nuts yield about 10 per cent, of the acid. Liebig has 
 also proposed a good process, which consists in heating a 
 mixture of crystallised gallic acid and pumice-stone in a 
 glass retort, a current of carbonic acid being passed 
 through it during the operation. One hundred parts of 
 gallic acid thus yield from thirty to thirty-three of pyro- 
 gallol. 
 
 Pyrogallol is very soluble in water and in alcohol, 
 somewhat less so in ether. It imparts an indigo-blue 
 coloration to the protosalts of iron, and a red coloration 
 with the persalts, but no precipitate is formed. It reduces 
 the salts of gold, silver, mercury, and platinum to a metallic 
 state, which renders it so useful in photography ; with lime 
 water it gives a fine purple colour, which is very charac- 
 teristic, but soon changes to a deep brown. 
 
 In a dry state it undergoes no alteration in the air, but 
 in solution it is quickly changed, becoming brown. This 
 oxidation takes place very rapidly in the presence of 
 alkalis, so that it may be substituted with advantage for 
 gallic acid in the analysis of gaseous mixtures. On the 
 evaporation of an alkaline solution of this acid, a black 
 gummy residue is left, containing carbonate and acetate of 
 the alkali metal. 
 
 Nitric acid converts pyrogallol into oxalic acid, and as 
 its aqueous solution is turned brown by a mere trace of 
 nitrous acid, it may be used as a reagent for the purpose of 
 detecting the presence of that body. Pyrogallol is com- 
 pletely oxidised by permanganate of potash, so that the 
 amount of the compound present in a solution, may be 
 ascertained by a standard solution of this salt. 
 
 It fuses at 240 F., and boils at 410 F. At 480 F. it 
 blackens, gives off water, and leaves an abundant residue of 
 metagallic acid : 
 
 C 6 H 6 3 = C 6 H 4 2 + OH, 
 
 Pyrogallic Metagallic 
 
 acid, acid. 
 
318 DYEIXG AND CALICO PRINTING. 
 
 GALLEIN. — This is a red dye, discovered by Baeyer,* 
 which is very similar in its properties to haematei'n. It is 
 prepared by heating a mixture of pyrogallol with phthalic 
 anhydride to 390 F. for several hours. As soon as the 
 reaction is complete, which is known by the mixture be- 
 coming thick, it is allowed to cool, then dissolved in boiling 
 alcohol, filtered, and the filtrate poured into a large quan- 
 tity of water. The brown precipitate of nearly pure gallei'n 
 thus produced may readily be obtained in a crystalline 
 state by dissolving it in hot dilute alcohol and allowing the 
 solution to cool. The crystals are brown by transmitted, 
 but blue by reflected light ; when its solutions are allowed 
 to evaporate spontaneously, the residue has a greenish- 
 yellow metallic lustre. Gallei'n, G»H u 7 , is almost in- 
 soluble in cold water, and but little soluble in hot water, 
 yielding, however, a red solution. It dissolves readily in 
 alcohol, and also in alkaline solutions, the latter having a 
 splendid blue or violet colour. 
 
 Gallei'n, when treated with reducing agents such as zinc 
 and sulphuric acid, is converted into a colourless compound, 
 galliii, C 20 H ls O 7 , just as haematei'n is converted into haema- 
 toxylin. The gallei'n should be boiled with a large 
 quantity of water and some sulphuric acid and zinc until 
 the liquid becomes yellow. On cooling, oily drops separate, 
 which soon solidify to a crystalline mass of impure gallin. 
 It is best purified from the unaltered gallei'n, by crystallisa- 
 tion from a hot solution of pyrogallol. It forms lustrous 
 prisms, which are nearly colourless when first obtained, but 
 gradually assume a red colour on exposure to the air, 
 especially in the presence of ammoniacal vapours. 
 
 The colours which gallei'n gives on cloth mordanted with 
 
 alumina or iron have a bluer tinge than those obtained 
 
 with logwood, and are finer and more stable, resembling 
 
 those of barwood. With a lead mordant it produces a 
 
 *Deut. Chem. Ges. Ber., iv., 457, 555, and 663. 
 
GALLEIN.— CCER ULEIN. 3 1 9 
 
 brilliant violet-blue, which resists the action of soap ex- 
 tremely well. Similar colours are produced by gallin. 
 The annexed interesting specimen, which we owe to the 
 generosity of M. H. Koechlin, is gallei'n, fixed by means 
 of alumina and oxide of tin. 
 
 GALLEIN. 
 
 Ccerulehi. — This compound is formed when gallein is 
 heated with twenty times its weight of concentrated sul- 
 phuric acid to 390 F. ; the red colour which the solution has 
 at first, gradually changing to a greenish-brown. When the 
 reaction is terminated, — which may be known by a sample 
 giving dark flocks when heated with water, but without 
 colouring the solution, — the product is poured into a large 
 quantity of water, and the voluminous nearly black precipi- 
 tate thoroughly washed with hot water. The precipitate, 
 which consists of pure ccerulei'n, has a composition repre- 
 sented by the formula C 2( ,H 10 O 7 , and its formation from 
 gallein may be thus represented : — 
 
 C 20 H 12 O 7 = C 20 H 10 O 7 + H 2 . 
 
 Gallein. Ccerulein. 
 
 When dry it forms a bluish-black mass, which is but very 
 slightly soluble in water, alcohol, or ether; it dissolves 
 
120 
 
 DYEIXG AXD CALICO PRIXTIXG. 
 
 readily, however, in hot aniline, with a magnificent blue 
 colour, and this solution, when diluted with alcohol, and 
 slightly acidified with acetic acid, dyes wool indigo-blue. 
 Ccerulei'n dissolves in alkaline solutions with a magnificent 
 green colour, which is unaltered by exposure to the air, 
 and yields green lakes with the earths. Cotton mordanted 
 with alumina is dyed a fine green in a bath of this colour, 
 whilst with iron mordants a brown is obtained. These 
 shades resist soaping extremely well, and rival the madder 
 colours in fastness. 
 
 Ccerulei'n, when treated with reducing agents, behaves 
 like gallei'n, yielding a colourless substance, coerulin, which 
 dissolves in ether, forming a yellow liquid with a beautiful 
 green fluorescence. It is most easily obtained by acting 
 on an ammoniacal solution of ccerulei'n with zinc dust. 
 
 Ccerulei'n resembles lo-kao in yielding a green alumina 
 lake, and in being reduced by treatment with ammonia 
 and zinc dust, although the difference in properties of the 
 reduced products renders it extremely improbable that the 
 two colouring matters are identical. The accompanying 
 specimen of ccerulein, which has also been presented by 
 M. Koechlin, is fixed by means of alumina. 
 
 
 CCERULEIN. 
 
ELLA GLC A CID.— GALL-NUTS. 32 1 
 
 Both galle'in and ccerule'in are now made on a large 
 scale by Messrs. Durant and Huguenin, of Bale. 
 
 ELLAGIC Acid. — This acid was discovered by Chevreul 
 in iS 1 5, who assigned to it the formula C 14 H 6 8 , 20H 2 . 
 Schiff finds, however, that the pure acid dried at 230 F. is 
 C u H 8 9 . It is deposited as a grey powder when a solu- 
 tion of gall-nuts is exposed to the atmosphere. To obtain 
 it pure, the powder is thoroughly washed with water to 
 remove the gallic acid, &c, then dissolved in potash, and 
 precipitated from this solution by an acid. It is finally 
 washed and dried. It has also been found amongst the 
 products obtained by heating gallic acid with dry arsenic 
 acid. 
 
 This acid is sometimes called bezoardic acid, from being 
 found in certain oriental bezoars : these are intestinal calculi 
 of various species of herbivorous animals, which eat the 
 leaves of some astringent plants. 
 
 Ellagic acid is a light, pale yellow, crystalline powder, 
 composed of very small transparent prisms which are 
 insoluble in water, but soluble in alcohol. It colours a 
 neutral solution of perchloride of iron, first greenish, but 
 after a time, bluish black. This acid is soluble without 
 decomposition in sulphuric acid, whilst nitric acid converts 
 it into oxalic acid. Heated at 21 2° F. it loses a molecule 
 of water, and at a higher temperature it is decomposed 
 without previously entering into fusion, and leaves a 
 charred mass covered with crystals. 
 
 Gall-Nuts. — These are the most valuable of all tannin 
 matters. They are produced by the females of an insect 
 called the Cynips folii quercus, which pierce the buds on 
 the young branches of the Quercus infectoria, a tree grow- 
 ing especially in the East. The egg being deposited in the 
 bud, the latter loses its natural growth and swells out to 
 the size of a hazel nut, having a green, red, or pink colour. 
 The eggs thus enclosed soon hatch, and the insect under- 
 W 
 
322 DYEING AND CALICO PRINTING. 
 
 goes all its metamorphoses until it attains the perfect 
 state, when, if allowed (which is not to the interest of 
 either the gatherer or consumer), it makes a hole and 
 escapes. Good gall-nuts should not be so pierced, and 
 they should be of a fresh bluish-green colour, having a 
 prickly surface. If the insect has escaped, they are yellow, 
 and are not of nearly so good quality, a great part of the 
 tannic acid having disappeared. In the market, the nut- 
 galls generally bear the name of the port from which they 
 are shipped. Thus, there are Aleppo galls, which are con- 
 sidered the best, then the Morea, Smyrna, &c. 
 
 They have received many applications in various manu- 
 factures. The best qualities are employed in the prepa- 
 ration of tannic, gallic, and pyrogallic acids, and in the 
 dyeing of silk. The white gall-nuts are used to produce 
 blacks on morocco and other similar classes of leather. 
 
 The following may be considered as the composition of 
 an average sample of gall-nuts : — 
 
 Tannic acid . « 65 "o 
 
 Gallic acid 2 'o 
 
 Ellagic acid 2-0 
 
 Chlorophyll and Volatile oil 7 
 
 Brown extractive matter 2-5 
 
 Gum 2"5 
 
 Starch 2 - o 
 
 Lignin 10-5 
 
 Sugar albumen, &c, and ash 1*3 
 
 Water 11-5 
 
 IOO"0 
 
 A solution of gall-nuts gives the following reactions : — 
 
 Salts of copper, chromium, and gold. Brown precipitate. 
 „ bismuth and mercury. Orange precipitate. 
 
 „ lead and antimony. White precipitate. 
 
REACTIONS OF GALL-NUTS. 323 
 
 J Dirty yellow pre- 
 Salts of silver, tin, cobalt, and cerium ) . ., . 
 
 ( Blood-red precipi- 
 „ titanium. \ 
 
 \ tate. 
 
 f Red or chocolate 
 „ uranium. \ 
 
 v. precipitate. 
 
 . ,. { Dark screen pre- 
 
 „ platinum. -j 
 
 osmium. \ 
 
 cipitate. 
 Bluish-purple pre- 
 cipitate. 
 
 Gall-nuts only impart a yellowish-green shade to animal 
 fibres, but with an iron mordant they give shades varying 
 from grey to bluish-black, according to the amount of 
 mordant employed. They are used as mordants for 
 various colouring matters in conjunction with alumina, and 
 the order in which these two mordants are applied, makes a 
 considerable difference in the intensity of shade obtained. 
 If the alumina be first applied, and the fabrics then passed 
 through a bath of decoction of galls, far more colour can 
 be fixed than when the process is reversed. 
 
 Gall-nuts are the only available source for the production 
 of tannic acid and its derivatives. 
 
 An inferior quality of gall-nuts is also sold, which is 
 found on the Qucrais rubur, an oak indigenous to Hungary, 
 Styria, Croatia, and Piedmont, in which countries it grows 
 with great luxuriance. It is a peculiar excrescence which 
 prevents the growth of the acorn or gland, and in which 
 the insect undergoes its metamorphosis. These gall-nuts 
 bear the name of ' ' knopperns\ and are employed to tan 
 leather, which they do more rapidly than oak bark. They 
 are also used in Germany, in calico printing, to produce 
 drabs, greys, and blacks. 
 
 Chinese Galls or Japanese Galls. — These are about 
 the size of a walnut, and very irregular in shape, having 
 pointed and curved excrescences. They are formed upon 
 
324 DYEIXG AXD CALICO PRINTING. 
 
 the leafstalks and branches of a species of sumach, Rhus 
 semialata, which is common in Northern India, China, and 
 Japan. They are remarkably rich in tannin, which appears 
 to be of the same nature as that existing in ordinary 
 Aleppo galls, since it furnishes gallic acid and pyrogallol 
 when decomposed. 
 
 VALONIA. — Valonia is the commercial name for the large 
 capsules or acorn cups of the Quercus cugylops, which are 
 shipped in considerable quantities from Smyrna to Trieste 
 and this country, where they are used for tanning, being 
 much richer than bark in tannin matters. Valonia is some- 
 times employed to adulterate garancin, to which it imparts 
 a greater power of dyeing purple shades. 
 
 Sumach. — Sumach, as Stenhouse's researches have 
 shown, is the only tanning or astringent matter, besides 
 Chinese galls, in which the tannin is identical with that of 
 gall-nuts. In sumach, however, there is a comparatively 
 large quantity of gallic acid present, as also a soluble 
 yellow principle. 
 
 Sumach is found in commerce as a coarse powder, 
 obtained by grinding under mill-stones the leaves of several 
 varieties of TerebintJiacece. The species most cultivated is 
 the Rhus coriaria, which came originally from Asia, but is 
 now extensively grown in Sicily, France, Spain, and 
 Portugal. The shrub attains a height of about 16 feet in 
 the most arid soils, and the branches are cut down every 
 year level with the ground. 
 
 There is a great difference in the amount of tannin 
 matter found in the various sumachs which occur in com- 
 merce, but there is no doubt that that obtained from the 
 Rhus coraria is the best, whilst the most inferior is that 
 grown in the south of France, the produce of the Coriaria 
 myrtifolia. The sumachs imported into Fngland bear the 
 name of the countries whence they are obtained. 
 
 A decoction of sumach, which has a greenish-yellow 
 
REACTIONS OF SUMACH. 
 
 325 
 
 hue, and a peculiar odour, has a distinctly acid reaction, 
 becomes turbid on cooling, and gives the following re- 
 actions : — 
 Gelatin. Abundant white precipitate. 
 
 {White precipitate, which takes a 
 green or reddish shade if an ex- 
 cess of alkali be added. 
 Lime, baryta, and ("White precipitate, passing to green 
 strontia waters. I or red, on exposure to air. 
 
 Render it more or less turbid. 
 Abundant pale yellow precipitate, 
 f Floculent canary-coloured precipi- 
 I tate. 
 
 ( Floculent yellowish-brown precipi- 
 \ tate. 
 
 {Colours the liquor blue with a 
 slight greenish tint, and gives an 
 abundant blue precipitate. 
 ( Abundant yellowish-white precipi- 
 1 tate. 
 Produces a remarkable effect, de- 
 
 Acids. 
 Alum. 
 
 Acetate of lead. 
 Acetate of copper. 
 
 Protochloride of tin. 
 
 Tincture of iodine. 
 
 S 
 
 Chlorine. 
 
 veloping a pink colour, which is 
 ' soon destroyed. 
 
 , Appears to act in a similar manner, 
 \ but the pink colour is weaker, and 
 ^ still more fugitive than that pro- 
 ^ duced by iodine. 
 In consequence of the powdered state in which sumach 
 is sold, the tannin matter it contains is easily affected by con- 
 tact with the air, and especially by damp, the gallotannic 
 acid which it contains being gradually decomposed into 
 gallic acid and glucose. Gallotannic acid combines with 
 gelatin, albumen, or the animal matters existing in skins, 
 producing an insoluble compound which fills the pores of 
 the animal tissue, and thus contributes, not only to prevent 
 
326 DYEING AXD CALICO PRIXTIXG. 
 
 its putrefaction, but also to render it impermeable to water ; 
 gallic acid, however, does not combine with the animal 
 matters, and can therefore take no part in the tanning or 
 curing of a hide. It will thus be readily seen that ex- 
 posure to the air or damp, rapidly deteriorates sumach for 
 the purposes of the currier, but even if kept dry the same 
 change goes on slowly, in consequence of the presence of 
 a ferment, so that the longer a sample is kept the less 
 value it has. 
 
 As already stated, gallic acid reduces the ferric salts (per- 
 oxide of iron) to the ferrous state (protoxide), the colour at 
 the same time disappearing, so that it is not available for 
 the purposes of the dyer of black silks, who uses sumach in 
 conjunction with persalts of iron and gelatin for weighting 
 the silk. For these purposes the tannic acid is the only 
 valuable constituent of sumach, and it is of great importance 
 to be able to ascertain with accuracy the amount of that 
 substance present in any given sample. Although sumach 
 is too expensive a tannin matter to be used for the tanning 
 of common leather, yet it is employed by the currier in the 
 preparation of skins for dyeing with light shades. It is 
 also extensively used for the dyeing and weighting of black 
 silk, although the colour so obtained is not equal to that of 
 gall-nuts. Greys are also produced on silk by means of 
 sumach. 
 
 Sumach, or more correctly the tannic acid it contains, 
 is used as a mordant on cotton and flax fibres to fix 
 colours which could not be otherwise employed; and this 
 property of tannic acid is often enhanced by passing the 
 goods, after they have been treated with sumach, through 
 a bath of protochloride of tin. It is largely employed for 
 this purpose in Yorkshire, either alone or in conjunction 
 with salts of tin, to mordant the cotton warps of the mixed 
 fabrics so extensively manufactured in that county. By 
 this means the cotton takes the same colours as the woollen 
 
DYEING WITH SUMACH. 327 
 
 weft, both with vegetable dyestuffs, and also with the 
 aniline colours. 
 
 Sumach is used in the production of cheap garancin 
 styles in calico printing, the tannin matters fixing the 
 colouring matters of the dyewoods, and increasing the 
 intensity of the purples and violets. An extract or de- 
 coction of sumach is also often used in printworks, to 
 produce a bright yellow with salts of tin; and a dark yellow 
 with sulphate of zinc. Sumach also, without a mordant, 
 yields a yellow colour to wool and silk. From this we 
 may infer that it contains a yellow colouring matter ; the 
 compound, however, has not as yet been isolated and 
 studied. 
 
 A decoction of sumach must be used immediately it is 
 made, as it contains a ferment called pectase, which at 
 ordinary temperatures quickly decomposes the gallo tannic 
 acid, whilst at 150° F. the fermentation takes place still 
 more rapidly. For the same reason the extract rapidly 
 deteriorates, becoming ropy, whilst at the same time an 
 abundant brownish-yellow precipitate is produced. The 
 author found some years ago that the addition of 1 per 
 cent, of carbolic acid to a decoction of sumach prevented 
 this decomposition taking place for a long time, and, as 
 phenol is a neutral substance, it does not interfere in the 
 least with the decoction, nor does it exert any injurious 
 action on the colouring matters with which it comes in 
 contact. 
 
 BABLAH. — Bablali* Babool,ov Neb-neb is the fruit of several 
 species of acacia. The principal varieties are East Indian 
 bablah, from the Acacia bambolak ; and Senegal and 
 Egyption bablah, from Acacia nilotica. The pericarp of 
 these fruits contains a dark brown astringent juice. The 
 aqueous extract contains, according to Chevreul, gallic and 
 tannic acids, red colouring matter, and a nitrogenous sub- 
 * Watts' Dictionary of Chemistry, i,, 480. 
 
328 DYEIXG AXD CALICO PRIX TING. 
 
 stance, besides other substances not yet examined. 
 East Indian bablah yields to boiling water 49 per cent, of 
 soluble matter; Senegal bablah 57 per cent; nevertheless, 
 according to Guibourt, the East Indian variety is richer in 
 tannic and gallic acids, and therefore more valuable. Bab- 
 lah is used in calico printing, in combination with iron and 
 alumina mordants, to produce various shades of fawn 
 colour. The tint produced by the seeds is different to that 
 obtained with the husks; the seeds are said to contain a 
 red colouring matter, and to be used in Egypt and India 
 for dyeing morocco. 
 
 CHESNUT Bark. — An extract from the bark of the 
 chesnut has long been used in Italy and the south of 
 France, and is still largely employed in Lyons to produce 
 cheap, fine, and fast blacks on silks. The solid extract has 
 been introduced into this country for dyeing silks and 
 cottons black. 
 
 Dividivi. — Dividivi is the fruit of the C<zsalpinia 
 coriaria. The plant is a native of the tropical part of 
 South America. As imported into this country, it has the 
 form of dark brown rolls containing a few flat seeds. It 
 contains a large quantity of tannic acid, together with 
 ready formed gallic acid. 
 
 MyrobalanS. — Myrobalans, are the dried nuts of the 
 Tcrminalia chcbula. It is imported chiefly from Calcutta, 
 and is largely used for tanning leather, and producing 
 blacks on wools. 
 
 Oak Bark. — Oak bark contains a glucoside called qner- 
 citannic acid, the composition of which has not yet been 
 determined. It gives the same reactions with persalts of 
 iron as gallo-tannic acid, but is not convertible into gallic 
 acid, and does not yield pyrogallic acid on distillation. 
 
 Spruce Bark, or Hemlock Tree.— Mr. J. L. Norton, 
 has proposed to use the extract of the bark of the hemlock 
 spruce, or Abies canadensis, as a substitute for that of 
 
CATECHU. 329 
 
 sumach in fixing the colouring matters obtained from coal- 
 tar. It is used for quick tanning. 
 
 WALNUT HUSKS. — A preparation from the husk of the 
 walnut, called Brou-de-noix, has long been employed, and is 
 still frequently used at the Gobelins, to obtain reddish- 
 brown hues, which are very fast, and do not require any 
 mordants. It is also employed to impart a darker shade 
 to certain colours. It is prepared by putting very ripe 
 walnuts into a cask with water, when after some time it is 
 ready for use as a dyestuff. 
 
 Mr. Phipson* has obtained from the husks of walnuts, a 
 yellow substance, crystallising in octahedra, to which he 
 has given the name regianin. It rapidly oxidises to a black 
 acid, which he calls rcgianic acid. He has also separated 
 a body similar to tannin, to which he gives the name of 
 nucitannin. Under the influence of mineral acids it splits 
 up into glucose, ellagic acid, and a new compound, rhotic 
 acid. 
 
 HENNIS. — Before passing from this class of tannin 
 substances, there is one which ought to be noticed, as it 
 has been used from the most ancient times in Egypt, 
 Arabia, and other Eastern countries, to dye wool, horse- 
 hair, leather, &c. It is made from the leaves of the Law- 
 sonia iuermis, which appears to be the gophcnvood of 
 Scripture, and the hennis of the Egyptians. The leaves 
 are mixed with water to form a paste of an orange-brown 
 colour. This paste is also employed by the Asiatic ladies 
 to dye the nails of their hands and feet, as well as their 
 ears and hair. 
 
 Catechu, Cutch, or Terra-Japonica, Gambier, 
 AND KlNO. — Catechu and gambier are the most valuable of 
 the tannin substances which give a green coloration with per- 
 salts of iron. They are very extensively used to produce a 
 great number of shades, varying from light drabs to dark 
 
 *Compt. Rend, lxxix, 1372. 
 
330 DYEING AND CALICO PRINTING. 
 
 brown, in cheap, dyed cotton goods, such as fustians and 
 corduroys. They are used in calico printing chiefly to 
 produce browns, in silk dyeing to weight the silk, and in 
 tanning to produce a low class of leather, easily distinguish- 
 able from that tanned with bark and other matters belong- 
 ing to the first class, because when used for making shoes 
 it communicates to the stockings a peculiar orange-yellow 
 hue. 
 
 For a long time there was much doubt as to the genus 
 of plants from which catechu, gambier, and kino, which 
 resemble each other very closely in their properties, were 
 derived. M. Guibourt, a few years ago solved the problem. 
 He found that real catechu, cittch, or terra-japonica, which 
 has been used in the East both in medicine, dyeing, and 
 tanning from time immemorial, is derived partly from the 
 softer parts of the wood and the pods of the Acacia catechu, 
 a tree belonging to the leguminous order, and partly from 
 the betel or areca nut, the fruit of the areca palm, or the 
 Areca catechu. These nuts, which are about the size of a 
 nutmeg and have somewhat the same appearance, are 
 largely used as a masticatory in Eastern countries. 
 For this purpose the crushed nut is generally used along 
 with the leaf of the betel pepper, and chunam or shell- 
 lime. To prepare catechu, the wood or nuts are boiled 
 in water, and when the solution has been evaporated to the 
 consistence of a syrup, it is spread on leaves or on the 
 ground, and solidifies on cooling. 
 
 Gambier is extracted from the leaves of the Uncaria 
 gambir, a shrub very abundant in India and the Malacca 
 Islands. The shrub belongs to the family Rubiacece and 
 to the same tribe as the cinchona. 
 
 Kino, improperly named in commerce gum-kino, is fur- 
 nished by several Indian plants, especially by the Butea 
 frondosa, belonging to the Lcguminoscz and the Pterocarpus 
 marsupium. It is used in India as a dyestuff for cottons, and 
 
VARIETIES OF CATECHU. 331 
 
 also as a medicine, but as it is not employed by English 
 dyers it is unnecessary to enter into a minute description 
 of it. 
 
 There are several varieties of catechu in commerce, but 
 the three which are principally used by dyers and calico 
 printers are all that need be noticed. The Bombay catechu, 
 which is the best, is obtained from the Areca catechu, and 
 occurs in dense, irregular lumps, of a dark brown colour, 
 weighing from 80 to 90 lbs., and is covered with leaves. It 
 is opaque, with an even, slightly unctuous, shining fracture. 
 Bombay catechu is almost entirely soluble in boiling water, 
 yields a dark brown liquor very rich in tannic acid, and 
 affords copious precipitates with gelatin, and with sulphuric 
 
 acid. 
 
 ■ 
 
 Bengal catecJiu is obtained from the Acacia catechu. It 
 has a lower specific gravity than the Bombay variety, and 
 is of a pale brown colour, with a yellowish cast. It is 
 opaque, with a glimmering lustre on the fractured surface 
 only, and is traversed by dark brown shining stripes. 
 When treated with cold water it leaves a large residuum, 
 but it is almost entirely dissolved by boiling water; the 
 solution contains less tannin, but more catechin, than that 
 from the Bombay variety. 
 
 Gambier catechu is imported from Batavia, and occurs in 
 cubical pieces of about an inch or rather more in size : it 
 is opaque, and of a brownish-yellow or bright yellow 
 colour. Its fracture is even and dull. It is only slightly 
 soluble in cold water, but almost completely in boiling 
 water, the solution affording copious precipitates with 
 gelatin, and with sulphuric acid. 
 
 All these products have an astringent taste, with a 
 sweet after flavour. They are soluble in alcohol, acetic 
 acid, and the alkalis, to which they impart a reddish-brown 
 colour. 
 
 The aqueous solution yields the following reactions : — 
 
332 DYEING AND CALICO PRINTING. 
 
 Gelatin. Abundant reddish-whiteprecipitate. 
 
 Alkalis. Give it a decidedly brownish hue. 
 
 Lime water. Yellowish coloration and precipitate. 
 
 „ , ( Clear the liquor, giving it a yellow- 
 
 Salts of alumina. \ . , , 
 
 (. ish hue. 
 
 Protosalts of iron. Olive-green coloration. 
 
 Persulphate of iron. Dark green coloration. 
 
 Sulphate of copper. Olive coloration. 
 
 f Abundant blackish-brown precipi- 
 Acetate of copper. \ 
 
 1 1 I tate. 
 
 Salts of lead. Yellowish-grey precipitate. 
 
 Bichromate of potash. Abundant brown precipitate. 
 
 Stenhouse was unable to obtain any glucoside by the 
 action of boiling dilute acid on catechu. Catechu, besides 
 varying widely in quality, is freely adulterated with mineral 
 substances, starch, tannin matters, and blood. Good 
 catechu should not contain more than 4 to 5 per cent, of 
 ash. To ascertain the presence of starch, the sample is first 
 treated with alcohol, and the insoluble residue then boiled 
 with water; if starch be present the solution will give a fine 
 blue coloration on the addition of iodine. The presence of 
 any ordinary tannin matter in the catechu will modify the 
 green coloration, which the latter substance gives with the 
 persalts of iron. Blood may be detected, if present, by 
 treating the catechu with alcohol, and after drying the 
 insoluble residue, heating it in a tube, when ammoniacal 
 vapours will be given off, and a most offensive odour pro- 
 duced. Good catechu should not leave more than 12 per 
 cent, of insoluble matter when treated with boiling alcohol. 
 
 Sometimes the yellow gambier is transformed into brown 
 catechu by melting it and adding 1 per cent, of bichromate 
 of potash, which imparts oxygen to the catechin, convert- 
 ing it into a brown resinous body. The melted mass is 
 then poured into wooden frames, and when cold has a 
 concho'idal fracture. This fraud may be easily discovered 
 
CA TE CHUTANNIC A CID. 333 
 
 by calcining the catechu, and testing the ash for oxide of 
 chromium. The best method, however, of ascertaining the 
 value of catechu, is to make comparative printing essays with 
 the sample to be tested and one of known good quality. To 
 effect this, Schiitzenberger recommends that 2 ozs. of 
 catechu be mixed with 4 ozs. of vinegar, and thickened 
 with gum. The mixture is then printed on the fabric, 
 which is afterwards steamed and passed through a weak 
 solution of bichromate of potash. After being washed 
 and dried, the intensity of the colour produced by the 
 different samples may be compared. 
 
 Catechu is composed of three substances, namely, a 
 tannin matter soluble in cold water, which has received 
 the name of cachoutannic, catechutannic, or mimotannic 
 acid, a white crystalline body called catechin, or catechuic 
 acid, and a brown amorphous matter formed by the 
 oxidation of catechin, during the evaporation of the de- 
 coctions of the plant or nuts. 
 
 Catechutannic acid. — The best method of preparing this 
 acid is that of Loewe,* who boils the pulverised catechu with 
 water, and after allowing it to stand for some days, separates 
 the catechin which has crystallised out, by filtration. The 
 aqueous solution of the impure acid is carefully evaporated 
 to dryness, dissolved in alcohol and filtered, sulphuric acid 
 being added to precipitate any lime that may be present. 
 In order to remove the excess of sulphuric acid, lead car- 
 bonate is added, and the lead in solution 'subsequently 
 precipitated by sulphuretted hydrogen : ether is then added, 
 to precipitate various resinous matters, and the solution 
 evaporated. After the residue has been dissolved in water, 
 and agitated with ether, to remove a small quantity of 
 catechin which is present, a solution is obtained which, 
 on evaporation, leaves pure catechutannic acid. Pelouze, 
 assigns to this acid the formula C 1S H 18 8 , but Loewe, who 
 
 *Jour. fur pr. Chem., cv., 32, 75. 
 
334 DYEING AND CALICO PRINTING. 
 
 has more recently examined the subject, makes it C 15 H u 6 . 
 Davy and Nees found that Bombay catechu, contained 
 about 54-4 per cent, of the acid, that from Bengal 48-2, and 
 Gambir 36 to 40. 
 
 It is readily soluble in water and alcohol, but insoluble in 
 ether. Its aqueous solution gives precipitates with gelatin 
 and with tartar emetic, and a green precipitate with the 
 persalts of iron. 
 
 On exposure to the atmosphere an aqueous solution of 
 this acid is gradually oxidised, becoming of a reddish 
 colour; when alkalis are present this change takes place 
 much more rapidly. 
 
 Catechin, or catechuic acid, may readily be obtained from 
 the impure catechin obtained in the preparation of catechu- 
 tannic acid, or from the residue left on exhausting 
 powdered catechin with cold water. This is dissolved in 
 about eight parts of boiling water containing a little acetic 
 acid, and lead acetate added. After separating the 
 precipitate by filtration, a current of sulphuretted hy- 
 drogen is passed through the liquid to remove the lead 
 in solution, and it is put aside to crystallise in a dark place. 
 Or, the impure catechin may be crystallised several times 
 from boiling water, with the addition of animal charcoal.* 
 
 The true formula for catechin is at present very doubtful. 
 Loewe makes anhydrous catechin C 10 H u O 5 , Kraut and van 
 Delden C 12 H 12 5 , whilst Hlasiwetz and Malin, who find 
 that catechin when fused with caustic potash is decom- 
 
 *As catechutannic acid, contrary to the statements in most handbooks* 
 is insoluble in dry ether, whilst anhydrous catechin is readily soluble, the latter 
 may be advantageously prepared by exhausting finely powdered catechin, 
 which has been dried at 212° F., with diy ether. On filtering the solution, 
 and distilling off the ether on the water bath, a pale yellow, thick oily fluid 
 is left, which, if poured out and exposed to the air for a few days, attracts 
 moisture and becomes converted into a crystalline mass of pure catechin. If a 
 pale-coloured catechu is selected, this forms by far the most convenient process 
 for obtaining pure catechin, whilst the residue, insoluble in ether, readily affords 
 catechutannic acid when treated by Loewe's process. — Eds. 
 
PROPERTIES OF CATECHIN. 335 
 
 posed into protocatechuic acid and phloroglucin, consider it 
 to be C 19 H 18 8 , and represent the decomposition just men- 
 tioned in the following manner: — 
 
 C 19 H 18 8 + O,, = C 7 H fl 4 + 2C H O 3 . 
 Catechin. Protocate- Phloroglucin. 
 
 chuic acid. 
 
 The amount of protocatechuic acid obtained by this means 
 is very small however. 
 
 Catechin is a white, silky, crystalline substance, consisting 
 of microscopic needles. It is very sparingly soluble in 
 cold water, but freely soluble in boiling water, its solutions 
 being neutral to litmus. It is also readily soluble in 
 alcohol and in ether. An alkaline solution of catechin 
 rapidly acquires a brown hue, and if acetic acid be now 
 added to it, the colour becomes less intense, and it gives 
 a precipitate with gelatin. When boiled with dilute sul- 
 phuric acid out of contact with air, it is decomposed 
 with formation of a brown powder, which has received 
 the name of catechuretin. The following equation repre- 
 sents the reaction which takes place: — 
 
 C 19 H 18 8 = C 19 H u 6 + 2 OH 2 . 
 
 Catechin. Catechuretin. 
 
 By dry distillation catechin yields pyrocatechin. 
 
 According to Svanberg, a solution of catechin, in presence 
 of caustic alkalis, rapidly absorbs oxygen, being converted 
 into japonic acid, which, on the addition of hydrochloric 
 acid, is thrown down as a black precipitate. In presence 
 of alkaline carbonates, catechin is converted into a red 
 compound called r ub ink acid \ this compound is, however 
 very unstable. . 
 
 Protocatechuic acid is produced not only from catechu, but 
 also when piperic acid, gamboge, scoparin, dragon's blood, 
 the tannin of the horse chesnut, or of larch bark, and 
 many other vegetable substances are fused with potash ■ it 
 is, however, most conveniently prepared from kino. In 
 
336 DYEIXG AND CALICO PRINTING. 
 
 order to extract it, the fused mass is dissolved in water, 
 acidulated with sulphuric acid, and the filtered solution 
 agitated with ether. On evaporating the ethereal solution, 
 a crystalline mass is left, which may be purified by pressure 
 between bibulous paper, and recrystallisation. 
 
 Protocatechuic acid forms thin prismatic needles, or 
 laminae, having the formula C 7 H 6 4 , OH 2 . It is soluble 
 in water, alcohol, and ether. Its aqueous solution gives a 
 dark blue coloration with perchloride of iron, which be- 
 comes red on the addition of an alkali. When heated to 
 212° F. it loses an equivalent of water, and the dehydrated 
 acid then melts at 390 F. It is decomposed by dry distil- 
 lation into pyrocatechin and carbonic anhydride. 
 
 C 7 H 6 4 = C G H 6 2 + C0 2 . 
 
 Protocatechuic Pyrocatechin. 
 
 acid. 
 
 Pyrocatechin or pyrocatecJiuic acid, formerly called oxy- 
 plicnic acid, besides being produced from catechin and 
 protocatechuic acid, is obtained, according to Eissfeldt and 
 Uloth, by the dry distillation of all those kinds of tannin 
 which turn persalts of iron green. When pure, it forms thin 
 white lustrous laminae, resembling benzoic acid in appear- 
 ance. It fuses at 240 F., and dissolves readily in water 
 and alcohol. It is also soluble in ether and in benzene. 
 It gives with persalts of iron a dark green coloration, a 
 black precipitate being deposited after a time ; with gelatin 
 it gives no precipitate. 
 
 Loewe considers that catechu contains, besides the 
 catechin and catechutannic acid, three other substances 
 soluble in water, namely — mimotannihydrorctin and the 
 japonic and rubinic acids already mentioned ; they are 
 soluble in alcohol, but precipitated from that solution by 
 ether. 
 
 Catechu is extensively employed for dyeing cotton, 
 especially fustians, owing to the great variety of drab 
 
DYEING WITH CATECHU. 337 
 
 shades which it yields with various mordants. By these 
 means, greenish or grey-drab shades are produced with 
 aluminous mordants alone; yellow-drabs, light yellows, and 
 chamois tints, with chloride of tin, to which red tints may 
 also be imparted by means of the red dyewoods ; and 
 various shades of brown with iron mordants, which may be 
 fixed and intensified by passing the goods through a weak 
 bath of bichromate of potash. 
 
 Dyers avail themselves of the colouring properties of 
 both catechutannic acid and catechin, whilst the calico 
 printer, who uses the catechu merely for the production of 
 browns, requires only the catechin, which he introduces 
 into the fibre, and then oxidises into the insoluble japonic 
 acid. The process employed is as follows : — A hot decoc- 
 tion of catechu is made, acetic acid or caustic soda being 
 added, and the solution filtered through filtering cloth. If 
 light shades are required, it is thickened and printed on the 
 fabric, which is then exposed to the atmosphere for oxida- 
 tion ; if darker ones are required the fabric is passed 
 through a weak solution of bichromate of potash ; whilst if 
 rich dark browns are to be produced, a salt of copper, and 
 
 CATECHU BROWN (LIGHT SHADE). 
 
338 DYEIXG AXD CALICO PRIXTIXG. 
 
 CATECHU BROWN (DARK SHADE). 
 
 salammoniac are added to the thickened decoction before 
 printing, the goods being subsequently steamed and passed 
 through a bichromate bath. The copper salts and 
 bichromate of potash completely oxidise the catechin into 
 japonic acid, giving thus the rich catechu browns so much 
 used at present. The preceding light and dark brown 
 samples we owe to the kindness of Messrs. Salis Schwabe 
 and Co., of Manchester. 
 
 If dyers, instead of employing catechu as imported, were 
 to grind it, and wash with cold water, they would obtain 
 an extract which would yield very pure shades of green- 
 drabs, whilst the insoluble residue of catechin would give a 
 great variety of tints. 
 
 Determination of Tannin. — From the facts already 
 stated, it must be obvious to all who use tannin matters, 
 whether tanners or dyers, that these substances not only 
 vary in value, according to the variety of plant from 
 which they have been obtained, and the country whence 
 they arc imported, but by the wilful addition of foreign mat- 
 ters such as starch, ochre, &c, to catechus; sand, and other 
 mineral substances to sumachs, these being sources of deteri- 
 oration which cannot be detected by mere inspection. 
 
DETERMINATION OF TANNIN 339 
 
 There is again another class of adulterations, such as the 
 addition to a new sumach of a quantity of a comparatively 
 old one, a fraud which it is impossible to discover by the 
 eye. The only method therefore of ascertaining the value 
 of the various astringent substances met with in commerce, 
 is to determine chemically the amount of tannin they con- 
 tain. This may be done with great accuracy by the follow- 
 ing process: — A weighed quantity (say 100 grains) of the 
 substance to be tested is boiled with distilled water, and 
 the decoction run off into a beaker without filtering. This 
 process is repeated four or five times. A test solution is 
 prepared by dissolving I drachm of gelatin in 4 ozs. of 
 water, and adding 15 grains of powdered alum to the solu- 
 tion. One hundred and fifty-five grains of this solution 
 represent about 5 grains of pure tannin. The test fluid 
 is carefully dropped into the beaker until, on the falling of 
 a drop upon the surface, the characteristic ring of tannate 
 of gelatin is no longer produced. In most cases the super- 
 natant liquid is not perfectly clear, so that it is difficult 
 to ascertain when the exact amount of the gelatin solution 
 has been added. In this case it is better to filter a small 
 portion of the solution, which may be readily done by 
 means of a glass tube, into the end of which a piece of 
 good sponge has been inserted. This end of the tube is 
 plunged into the liquid and suction applied. The quantity 
 of test fluid used is then ascertained, and from this the 
 percentage of tannin is calculated by comparison with the 
 amount required to precipitate a solution containing a 
 known quantity of pure tannin. The above process, when 
 carefully carried out, will give correct results as to the com- 
 parative value of tannin matters. 
 
 Although several elegant and rapid processes, based on 
 the employment of oxidising agents, have been proposed 
 for* determining the value of tannin substances, yet there 
 are sources of serious error arising from the presence of 
 
340 
 
 DYEING AND CALICO PRINTING. 
 
 other oxidisable substances, such for instance as gallic 
 acid, which are of no value whatever either to the dyer, 
 the calico printer, or the tanner. 
 
 The following table, taken from Dr. Ure's work, shows 
 the quantity of extractive matter and tannin in ioo parts 
 of several substances : 
 
 White inner bark of old oak 
 
 „ young oak 
 
 „ Spanish chesnut . 
 
 „ Leicester willow. 
 
 Coloured or middle bark of oak 
 
 „ Spanish 
 
 chesnut . 
 
 ,, Leicester 
 
 willow . 
 
 Entire bark of oak 
 
 In 4S0 
 
 by 
 Davy. 
 
 72 
 
 77 
 63 
 79 
 19 
 
 14 
 
 16 
 29 
 21 
 33 
 13 
 11 
 
 78 
 79 
 
 ,, Spanish chesnut ... 
 
 „ Leicester willow ... 
 
 „ elm 
 
 common willow . . . 
 
 Sicilian sumach 
 
 Malaga sumach 
 
 Souchong tea 48 
 
 Green tea 41 
 
 Bombay catechu 261 
 
 Bengal catechu 231 
 
 Gall-nuts 127 
 
 Bark of oak, cut in winter 
 
 „ beech 
 
 „ elder 
 
 „ plum-tree 
 
 „ trunk of willow 
 
 „ sycamore 
 
 In 8 oz. 
 
 by 
 Biggins. 
 
 3° 
 
 In 100 
 
 parts by 
 
 Cadet de 
 
 Gassin- 
 
 court. 
 
 21 
 
 IO9 
 28 
 
 (boughs) 31 
 158 
 
 46 
 
 o 
 3i 
 4i 
 
 58 
 52 
 53 
 
 16 
 
SUBSTANCES YIELDING TANNIN 
 
 341 
 
 In 100 
 
 parts by 
 In 4S0 In 8 oz. Cadet de 
 
 by 
 Dav 
 
 Bark of birch 
 
 „ cherry-tree 
 
 „ sallow 
 
 „ poplar 
 
 ,, hazel 
 
 „ ash 
 
 „ trunk of Spanish chesnut 
 
 „ smooth oak 
 
 „ oak cut in spring 
 
 „ alder 
 
 „ apricot 
 
 „ pomegranate 
 
 , , Cornish cherry-tree 
 
 „ weeping willow 
 
 „ Bohemian olive 
 
 „ tan shrub, with myrtle leaves... 
 
 „ Virginian sumach 
 
 „ green oak 
 
 „ service-tree 
 
 „ rose chesnut of America 
 
 „ rose chesnut 
 
 „ rose chesnut of Carolina 
 
 „ sumach of Carolina 
 
 Root of tormentil 
 
 Cornus sanguinea of Canada 
 
 by 
 Biggms. 
 
 Gassin- 
 court. 
 
 54 
 
 
 59 
 
 24 
 
 59 
 76 
 
 ... 
 
 79 
 82 
 
 ... 
 
 98 
 
 ... 
 
 104 
 108 
 
 ... 
 
 
 
 36 
 
 
 
 32 
 
 
 
 32 
 
 
 
 19 
 16 
 
 
 
 14 
 
 
 
 13 
 
 
 
 10 
 
 
 
 10 
 
 
 
 8 
 
 
 
 8 
 
 
 
 6 
 
 
 
 6 
 
 
 
 5 
 46 
 
 
 • • 
 
 44 
 
CHAPTER XI. 
 
 ON THE EXAMINATION OF COLOURING MATTERS 
 AND COLOURED FABRICS. 
 
 The previous chapters having been devoted to a con- 
 sideration of the properties of the various colouring matters 
 other than those derived from coal-tar, it will now be 
 advisible to notice the methods employed for the deter- 
 mination of the nature of a colouring matter fixed on a 
 fabric; to recapitulate to some extent the methods of 
 detection of various adulterations; and to give the most 
 important processes for determining the comparative com- 
 mercial value of particular samples. 
 
 Beginning with the latter point as the least complex, we 
 may premise that in many cases it is impossible, and in 
 nearly all extremely tedious and difficult to separate the 
 colouring matters in a state sufficiently pure, or in such a 
 definite combination as to enable us to weigh them directly: 
 we must therefore adopt the artifice of making a compari- 
 son of the sample, the value of which it is desired to ascer- 
 tain, with that of a standard sample of known good quality, 
 or having a known value. 
 
 In many cases the simplest method of doing this is by 
 means of an instrument called the 'colorometer,' in which 
 the depth of colour of solutions of the sample to be tested 
 and of the standard may be compared. A known weight 
 of the colouring matter is taken, and the colour extracted 
 by water, or alcohol, or in some cases by a solution of 
 alum, or some other solvent especially adapted to the 
 colouring matter under consideration. The solutions, when 
 made up to an equal volume, are ready for comparison. 
 
COL OR METERS. 
 
 343 
 
 The earliest instrument devised for this purpose was that 
 of M. Houton-Labillardiere. It is very simple, being 
 composed of two glass tubes, about half-an-inch wide and 
 14 or 15 inches high, closed at the bottom, and placed side 
 by side on a stand. The tubes are graduated either 
 throughout their entire length or only on the upper half. 
 A quantity of the solution to be tested is then placed in 
 one of the tubes, filling it one-half. The standard solu- 
 tion is then filled to the same point in .the other tube, and 
 water, or alcohol, as the case may be, is added to the darker 
 solution (which will in most cases be the standard,) until 
 the depth of colour in both tubes is the same. The values 
 of the two samples will of course be in direct proportion to 
 the relative volumes of the solutions in the tubes when the 
 intensity of the tint is the same in both. Thus, suppose 
 fifty divisions of the original solution has been taken, and 
 it has been necessary to add ten divisions of water to the 
 standard, the value of the standard sample and that to be 
 tested will be as 60 : 50 :: 100 : 83.33, or the sample con- 
 tains five-sixths of the colouring principle that the standard 
 does. This apparatus may be replaced by two burettes of 
 the same diameter. 
 
 The first improvement on this plan was to place the tubes 
 in an oblong box, Fig. 12, a kind of camera obscura, 
 having two holes in 
 the top, near one end, 
 of a diameter equal to 
 that of the tubes. At 
 the end, directly in a 
 line with these holes, 
 are two slits, also the 
 same width as the 
 tubes. At the other 
 end is a hole by FlG - I2 ' 
 
 which, on placing the tubes containing the solutions 
 
344 
 
 DYEJXG AXD CALICO PRIXTIXG. 
 
 & 
 
 V 
 
 in the apparatus, and turning the slits to the light, 
 the lower portion of the tubes can be seen. As no light falls 
 on them, except through the slits, greater accuracy may be 
 obtained than by the first method. 
 
 M. Collardeau has proposed an instrument on a some- 
 what different principle: instead of diluting the stronger 
 
 liquid, he lengthens 
 the column of the 
 weaker fluid, until, on 
 looking through it, the 
 intensity of colour ap- 
 pears the same, and 
 the values are in in- 
 verse ratio to the 
 length of the columns. 
 His apparatus consists 
 of two tubes, t,t', Fig. 
 13, fixed horizontally 
 on a support,and which 
 Fig. 13. can be drawn out like 
 
 a telescope; they are impermeable, and are closed at 
 their extremities a, by discs of glass. The sliding tubes 
 are furnished with scales, by which the depth of column 
 may be ascertained. By means of a small tube com- 
 municating with the vessels containing the respective 
 liquids, the larger tube may be kept filled. 
 
 M. A. Miiller has described an instrument depending 
 for its action on the production of white light, by passing 
 the light first through the coloured solution, and then 
 through a disc of glass of the colour complementary to 
 that of the solution. The difference of the depth of 
 columns necessary to produce the white light giving the 
 difference in value. 
 
 MM. Dubosc and Mene, have proposed an apparatus 
 Consisting of parallel tin tubes to contain the liquids. At 
 
COL OR OME TERS. 
 
 345 
 
 the lower part of the tubes a mirror is fixed similar to that 
 for a microscope. At the upper part of the tubes prisms 
 are so placed that the light from them forms, at the point 
 of sight, a disc divided into two parts, consequently, when 
 the liquids arc equally coloured, there will be a uniform 
 coloration of the disc. An instrument on this principle, 
 devised by Mr. R. P. Wilson, is now employed in testing 
 the value of petroleum, with the difference, however, that 
 the colour of the standard is obtained by means of stained 
 glass, but with a very little alteration this instrument would 
 be well adapted for a colorometer. Fig. 14, represents Mr. 
 Wilson's apparatus: a, a, a, is one of the two tubes which 
 
 Fig. 14. 
 are attached side by side to the hinged lid of the box, and 
 filled with the two liquids, the colours of which are to be 
 compared ; g is a mirror by which the light is reflected and 
 caused to pass through the two tubes, where it is received 
 
346 DYEING AND CALICO PRINTING. 
 
 at the upper end on glass prisms. These are so arranged 
 that on looking through the eye-piece h, a circular field is 
 seen divided down the centre by a perpendicular line ; one 
 half of the field being illuminated with the light which has 
 passed through one tube, and the other half with the light 
 which has passed through the second tube. By this means 
 the colour of the two semi-circular discs may readily be 
 compared. The piece marked e,f, is a link furnished with 
 a ' set screw, so that the lid of the box to which the tubes 
 are attached, may be set at any desired angle ; whilst at i, 
 pieces of standard coloured glass may be introduced for 
 comparison opposite the end of one of the tubes, which in 
 that case is filled with water. 
 
 Closely allied to colorimetry is the detection of colours 
 by means of the spectroscope, but this, of course, can only 
 be a qualitative not a quantitative process. There is no 
 doubt that before very long, this instrument will prove a 
 most valuable addition to our means of ascertaining the 
 presence of small quantities of colours. When speaking 
 of madder we have already had occasion to refer to the 
 marked difference observed by Professor Stokes, between 
 the spectrum of alizarin, and that of purpurin. He also 
 studied the spectrum of hoematosin, the colouring matter 
 of blood, and the results obtained by him were so remarkable 
 that they attracted the attention of Mr. H. C. Sorby, who 
 has devised an apparatus by means of which solutions of 
 the colouring matters can be examined spectroscopically. 
 This method has already been applied very successfully to 
 the determination of the age of wines, and also to the de- 
 tection of certain adulterations, but as the spectra of those 
 colouring matters which are usually met with in commerce, 
 are at present to a great extent unknown, the suggestions 
 he has given for a general method of procedure in the 
 examination of colouring matters, has not as yet been 
 rendered practically available. 
 
COMPARISON OF D YESTUFFS. 347 
 
 A second method of determining the relative value of 
 two samples of colour is by means of oxidising agents; 
 some processes of this nature, applicable in particular cases, 
 have been already described, but it must be remembered 
 that they are unreliable in direct proportion to the facility 
 with which the oxidising agent employed is reduced by 
 organic matters generally ; whilst even in the most favour- 
 able instances, the results obtained ought to be confirmed 
 by some other process. This is well illustrated in the case 
 of indigo. If a sample of indigo, which will only yield to 
 the dyer 60 per cent, of available colouring matter, be 
 tested by the oxidation process, it will show from 70 to 80 
 per cent, of indigotin ; other organic matters in the indigo 
 being oxidised at the same time. The oxidising agents 
 which have been proposed are permanganate of potash, 
 bleaching powder, chromic acid, bichromate of potash, and 
 potassium ferricyanide. 
 
 The third and most certain means of comparison is 
 founded on the relative dyeing powers of the samples and 
 the standard, and is, in fact, the carrying out on a small 
 scale of the processes followed on the large scale in the dye- 
 works. The apparatus best adapted for this purpose has 
 been already described at the close of the third chapter 
 (p. 105): the questions of temperature and time of course 
 vary with each dyestufif, and will be found described 
 under the respective colouring matters, or if not, may be 
 gathered from their properties. In all cases, however, 
 the experiments on the samples to be compared must be 
 carried on at the same time, under exactly the same con- 
 ditions; great care being taken not to have an excess of 
 the colouring matter, for the object is not to produce beauty 
 of shade in the dyed samples, but to ascertain the relative 
 amounts of colour in the respective dyestuffs; this can 
 only be effected by employing a smaller amount of colour- 
 ing matter than is necessary to obtain a full tone. 
 
348 DYEING AND CALICO PRINTING. 
 
 The principal mineral adulterations to which dyestuffs 
 are liable are sand and clay with red colouring matters; 
 powdered brick with yellow colouring matters; ochre with 
 tannin matters; chalk and white lead, and even an alu- 
 minous lake of logwood, with indigo; whilst talc and white 
 lead are common adulterations of cochineal. These may 
 all be easily detected by calcination, the amount of residue 
 showing whether any fraudulent addition of mineral matter 
 has been made. Starch is also an article commonly used 
 for purposes of adulteration. The presence of this body 
 may be proved by treating the dyestuff with dilute alcohol, 
 and then with cold water, which will in most cases remove 
 the colouring principle; on afterwards treating the residue 
 with boiling water, the starch will be dissolved, and may be 
 recognised by the blue coloration produced on adding a few 
 drops of tincture of iodine. The addition of a wood or bark 
 from which the colouring matter has been already extracted 
 is also sometimes resorted to, and although in some cases 
 it may not be possible to prove such addition, yet 
 the low dyeing power of such a sample will always be 
 shown in a comparative test, and its inferior value will be 
 manifested. The special adulterations to which individual 
 dyestuffs are liable having already been noticed when 
 treating of them, it is unnecessary to enter into the details 
 here. 
 
 The reactions offered by colours fixed on tissues are very 
 varied, and are also subject to modification, according to 
 the nature of the fibre on which they are fixed, but the 
 tables taken from the work of the late Professor Bolley, 
 which are given as an appendix at the end of the book, 
 are sufficient to guide the analyst as to the nature of the 
 colouring matter, and in most cases also as to the manner 
 in which it has been applied. The nature of the mordant 
 is ascertained by the incineration of a portion of the tissue 
 and the examination of the ash, except in the case of some 
 
TESTING FOR MORDANTS. 349 
 
 of the coal-tar colours which are fixed on cotton and linen 
 fibres by means of albumen, or sumach. If albumen has 
 been employed, it may be detected by the ammoniacal 
 vapours, and the peculiar odour given off during the com- 
 bustion of nitrogenised bodies; whilst, if sumach has been 
 used, a black coloration will be obtained if the fabric be 
 treated with a persalt of iron. This class of colours is 
 now also fixed in steam styles by means of arseniate of 
 alumina, produced on the cloth as follows :— The cloth is 
 first padded in a solution of acetate of alumina, and a 
 properly thickened solution of arsenic acid, glycerine, and 
 the colouring matter printed on, after which the cloth is 
 steamed. If this process has been adopted, the alumina 
 will of course be found in the ash ; but to detect the arsenic 
 acid, a portion of the coloured cloth must be heated in a 
 narrow test tube, just sufficiently to char the cloth, the 
 water given off must be removed by blotting paper or a 
 gentle heat, and the charred mass then heated to dull 
 redness, when the arsenic acid will be reduced, and a ring 
 of metallic arsenic will be formed on the cool portion of 
 the tube. 
 
CHAPTER XII. 
 
 BENZENE, ANILINE, AND MAGENTA. 
 
 This and the following chapters are devoted to a con- 
 sideration of the colouring matters obtained artificially 
 from the products of the destructive distillation of coal, and 
 which are generally known by the name of 'coal-tar 
 colours,' from the circumstance that they are prepared 
 indirectly from coal-tar. 
 
 The black, viscid liquid known as coal-tar, is a mixture 
 of a great number of chemical compounds of the most 
 diverse nature, as may be seen by an inspection of the 
 accompanying table, representing the substances which up 
 to the present time have been isolated from it. 
 
 NAME. i FORMULA. 
 
 BOILING 
 POINT F. 
 
 Hexane 
 
 QH-. 
 
 c : : 
 
 CtH u 
 
 C H- 
 
 '5«° 
 
 208° 
 
 about 320° 
 103° 
 149 
 
 " - 
 
 i 7 S ; 
 33 1 ' 
 
 Heptane 
 
 Octane 
 
 Decane 
 
 Amvlene 
 
 QH 
 
 C C H 12 
 
 C : H : . 
 
 1 1 1 :vlene (caproylene) 
 
 Heptylene (cenantlyne) ... 
 Paraffin* 
 
 Toluene 
 
 "i 
 
 Cumene 
 
 C G Hr. 
 C;H S 
 
 C; 
 
 C;H : _. 
 
 * Solid paraffin is a mixture of the higher members of the marsh gas and 
 define series, homologous with hesane and hexylene. 
 
COMPOUNDS IN COAL-TAR. 
 
 351 
 
 Cymene 
 
 Naphthalene 
 
 Anthracene 
 
 Chrysene 
 
 Pyrene 
 
 Bisulphide of Carbon 
 
 Hydrocyanic acid 
 
 Acetic acid 
 
 Phenol (carbolic acid) 
 
 Cresol (cresylic acid) 
 
 Phlorol (phlorylic alcohol) 
 
 Rosolic acid 
 
 Brunolic acid 
 
 Aniline 
 
 Pyridene 
 
 Picoline 
 
 Lutidine 
 
 Collidine 
 
 Parvoline 
 
 Coridine 
 
 Rubidine 
 
 Viridine 
 
 Leucoline 
 
 Lepidine 
 
 Cryptidine 
 
 Pyrrol 
 
 FORMULA. 
 
 CioH 14 
 CioHg 
 Cu-H 10 
 Ci 8 H 12 
 
 ^-16^10 
 
 cs 2 
 
 HCN 
 
 C 2 H 3 O.OH 
 QH 5 .OH 
 C 7 H 7 .OH 
 C R H 9 .OH 
 
 QH 7 N 
 
 C 5 H 5 N 
 
 C 6 H 7 N 
 
 C 7 H 9 N 
 
 C 8 H U N 
 
 C 9 H 13 N 
 
 C 10 H 15 N 
 
 C n H 17 N 
 
 C 12 H 1S N 
 
 C 9 H 7 N 
 
 C 10 H 9 N 
 
 C„H U N 
 
 C 4 H S N 
 
 BOILING 
 POINT F. 
 
 423 
 
 about 680° 
 ? 
 ? 
 
 "5° 
 
 79°-7 
 
 246°2 
 
 363 
 
 39 2 ° 
 428° 
 
 360° 
 
 243° 
 275° 
 3°9° 
 338° 
 
 37°° 
 412° 
 446 
 484° 
 
 455° 
 
 500 
 
 ? 
 
 272° 
 
 This list, however, is far from indicating the whole of the 
 constituents of coal-tar, very many substances undoubtedly 
 exist in it which have not as yet been obtained in a pure 
 state, and submitted to a careful investigation. 
 
 One of the most important of the substances above men- 
 tioned in connection with the coal-tar colours is aniline, 
 
352 DYE1XG AND CALICO PRINTING. 
 
 which, as already noticed (p. 158), was first discovered in 
 1826, by Unverdorben, amongst the products of the de- 
 structive distillation of indigo. He gave it the name of 
 'crystallin,' from its property of forming crystalline com- 
 pounds with various acids. Runge subsequently, in 1S34, 
 extracted a substance from coal-tar which gave a blue 
 colour with hypochlorite of lime, so he called it 'kyanol.' 
 In 1840, Fritzsche obtained a basic oil by distilling indigo 
 with caustic potash, to which he gave the name of aniline, 
 from the Portuguese word for indigo, anil; whilst two years 
 later, in 1842, Zinin prepared a base, 'benzidam,' from 
 nitrobenzene, by the action of ammonium sulphydrate. It 
 was reserved, however, for Hofmann, in his masterly re- 
 searches in connection with this subject, to show that all 
 these substances obtained in various ways and from various 
 sources were identical. 
 
 In order to separate the various constituents of coal-tar, 
 it is submitted to distillation in cylindrical retorts of cast 
 iron, holding from 1,000 to 2,000 gallons. The more vola- 
 tile hydrocarbons come over first, but as the distillation 
 proceeds the specific gravity of the product becomes 
 greater, until at last it ceases to float on water: this 
 first portion constitutes 'light oil,' or coal-tar naph- 
 tha. On proceeding with the distillation, the boiling point 
 of the distillate rises gradually, and it becomes denser and 
 denser, containing more and more naphthalene and anthra- 
 cene: this is the 'dead oil,' whilst the residue in the retort 
 is pitch, which is run out whilst hot and in the fluid state. 
 If, instead of running off the pitch at this stage, the fire be 
 urged, a semi-solid mass comes over containing anthracene, 
 chrysene, pyrene, and other hydrocarbons whose nature is 
 unknown ; whilst a hard, black, brilliant, rather porous coke 
 is left behind. 
 
 In order to obtain aniline directly from coal-tar, the 
 bases, of which it contains about 1 per cent., are extracted 
 
ANILINE FROM COAL-OIL. 353 
 
 by agitating the coal-oil, boiling between 300 and 450 F., 
 with hydrochloric or dilute sulphuric acid. After allowing 
 it to stand twenty-four hours, the oil is separated, and the 
 acid liquid agitated with a fresh quantity of oil, repeating 
 the operation until the acid is nearly saturated. The 
 aqueous solution is then distilled with excess of lime or 
 soda, the distillate neutralised by hydrochloric acid, and 
 concentrated by evaporation: on adding lumps of solid 
 caustic soda to this solution, the mixed bases are liberated, 
 and rise to the top of the liquid as an oily layer. In order 
 to separate the aniline, which forms but a small part of the 
 whole, the product is carefully and repeatedly rectified, and 
 the fraction, boiling at 350 to 365 R, converted into an 
 oxalate; this must be repeatedly crystallised from water 
 and from alcohol, and then decomposed by distillation 
 with an alkali. 
 
 Pure aniline may readily be obtained from indigo by 
 mixing it with a concentrated solution of potash, and dis- 
 tilling as long as anything passes over. The product merely 
 requires redistillation to be perfectly pure ; the amount 
 being about one-fifth of the indigo originally employed. 
 
 It is evident, however, that the direct extraction from 
 coal-oil of the large quantities of aniline required in the 
 manufacture of the aniline colours is too complicated, and 
 its purification too difficult to be of any practical use, whilst 
 .to prepare it from indigo Avould be far too costly. Fortu- 
 nately however, benzene, which occurs in considerable 
 quantity in coal-tar, can be easily transformed into aniline, 
 by two very- simple chemical reactions ; in the first of 
 these it is converted into nitrobenzene, which then, by the 
 action of reducing agents, yields aniline. 
 
 Benzene. — This hydrocarbon was discovered in 1825 by 
 
 Faraday, but its existence in coal-tar was first pointed out 
 
 by Hofmann in 1845, and Mansfield succeeded in preparing 
 
 it in considerable quantity from this source. It is obtained 
 
 Y 
 
354 DYEING AND CALICO PRINTING. 
 
 by the fractional distillation of the light oil after it has 
 been washed with milk of lime and then with water ; collect- 
 ing apart the portion boiling between 176 and 240 F. 
 This contains almost the whole of the benzene, together 
 with the greater part of the toluene, and after being treated 
 once or twice with 5 per cent, of concentrated sulphuric 
 acid, is again rectified ; that portion boiling about 176 to 
 212° F., being known in commerce as 'light benzol,' or '90 
 per cent, benzol'; whilst that from 21 2° to 250 F., is known 
 as ' heavy benzol,' or ' 50 per cent, benzol.' In order to 
 obtain perfectly pure benzene, the commercial article boil- 
 ing below 212° F., should be heated successively with small 
 quantities of sulphuric acid, until it ceases to blacken the 
 latter, and then submitted to fractional distillation. The 
 portion which comes over between 176 and 200° F., when 
 cooled by a freezing mixture of ice and salt, becomes 
 nearly solid from the separation of crystals of benzene : if 
 the mass be now strongly pressed, melted, and again 
 crystallised once or twice in a similar manner, it will be 
 obtained perfectly pure. Pure benzene may also be readily 
 prepared by the method devised by Mitscherlich in 1835, 
 which consists in distilling a mixture of one part of benzoic 
 acid with three parts of slaked lime. 
 
 At the ordinary temperature, benzene is a colourless, 
 mobile liquid, having a somewhat aromatic odour, and at 
 low temperatures solidifies to an almost transparent 
 crystalline mass, which melts at 50 F. Its density at 
 6o° F. is 0-85, and it boils at i77°-5 F. It is almost insolu- 
 ble in water, but is miscible in all proportions with alcohol 
 and ether. It is very inflammable, burning with a brilliant 
 smoky flame. 
 
 Nitrobenzenes. — By the action of nitric acid on ben- 
 zene under varying circumstances, it is possible to obtain 
 two nitrobenzenes, in one of which, the mono-nitrobenzene, 
 or as it is generally called, nitrobenzene, one atom of the 
 
MANUFACTURE OF NITROBENZENE. 355 
 
 hydrogen in benzene is displaced by the group N0 2 form- 
 ing the compound C 6 H 5 N0 2 , whilst in dinitrobeurjcnc, 
 C H 4 (N0 2 ) 2 , two of the hydrogen in benzene are displaced 
 byN0 2 . 
 
 Nitrobenzene was discovered by Mitscherlich in 1834, 
 who obtained it by the action of fuming nitric acid on 
 benzene. As, however, fuming nitric acid of specific gravity 
 1 "5 is costly, it was necessary to seek for some other means 
 of nitrating the benzene. Two* mixtures have been 
 employed for this purpose, one consisting of sodium nitrate 
 and sulphuric acid, the other of sulphuric acid, and ordinary 
 commercial nitric acid specific gravity 1*3 to i'35; the 
 latter is now generally preferred. 
 
 The process of converting the benzene into nitrobenzene, 
 is carried on in tall cast-iron pots, about 4 or 5 feet deep 
 and of the same width, provided with a closely-fitting 
 cover, through which passes the shaft of a stirrer, kept in 
 motion by machinery, so that the contents of the vessel 
 may be in constant agitation. Besides the stuffing box for 
 the shaft, there are two other openings in the lid, one to 
 introduce the necessary materials, and the other, furnished 
 with a long pipe, to carry off the nitrous fumes. Both this 
 pipe and also the lid of the apparatus are kept cool by a 
 current of cold water. The entire charge of benzene is first 
 introduced into the apparatus and the agitator set in 
 motion, the mixed acids are then gradually and cautiously 
 run in through a pipe provided for the purpose, but care 
 and experience are required to conduct the operation 
 successfully, as explosions are apt to occur if the acid be 
 added too hastily, or in too large quantities at a time. 
 
 After the requisite quantity of the mixed acids has been 
 added, and the reaction is complete, the contents of the 
 iron pot are drawn off by means of an opening at the 
 bottom provided for that purpose. The spent acids run 
 out ■ first, and then the nitrobenzene ; the latter is well 
 
356 DYEIXG AND CALICO PRINTING. 
 
 washed by agitation with water, and then rendered perfectly 
 neutral by means of a dilute soda solution. If it still con- 
 tains any unaltered benzene, this may be recovered by 
 distillation. 
 
 Pure nitrobenzene is a pale yellow liquid, having an 
 odour strongly resembling that of bitter almond oil, and 
 is very poisonous. Its density at 59° F. is 1*209; it boils 
 at about 420° F.. and at 2>7° F. it solidifies to a mass of 
 pale yellow needles. It is almost insoluble in water, but is 
 readily miscible with alcohol, ether, and benzene. 
 
 Dinitrobenzene, C c H 4 (N0 2 ) 2 , discovered by Sainte 
 Claire Deville in 1841, may be prepared directly from 
 benzene by the action of a mixture of sulphuric acid with 
 fuming nitric acid, or more conveniently, by heating nitro- 
 benzene with a mixture of nitric and sulphuric acids. The 
 crystalline cake which separates on cooling is washed, first 
 with water, and then with a dilute solution of carbonate of 
 soda, and finally crystallised from boiling alcohol. 
 
 Pure dinitrobenzene crystallises in long flat prisms, 
 which melt at 176" F., and are very soluble in ether, ben- 
 zene, and boiling alcohol. It is slightly soluble in boiling 
 water, crystallising out, on cooling, in long slender needles, 
 which are almost colourless. 
 
 Aniline. — As already noticed, although this base can be 
 obtained from indigo, and also directly from coal-tar, yet, 
 for manufacturing purposes it is universally prepared by 
 the action of reducing agents on nitrobenzene. 
 
 Zinin's process consisted in dissolving the nitrobenzene 
 in alcohol, adding ammonia, and saturating with sulphu- 
 retted hydrogen. After allowing the solution to stand 
 some time, a large quantity of sulphur is deposited, and 
 the liquid, on examination, will be found to contain aniline. 
 The reaction which takes place maybe thus represented: — 
 
 C 6 H 5 .X0 2 + 3 H 2 S = C 6 H 6 .NH, - 2 OH 2 + 3 S. 
 
 Nitrobenzene. Aniline. 
 
MANUFACTURE OF ANILINE. 357 
 
 Although the reaction is interesting from a scientific point 
 of view, and as being the first by which nitrobenzene was 
 transformed into aniline, it is quite unfit for the prepara- 
 tion of large quantities of material. Bechamp found, 
 however, that reduction took place with far greater facility 
 on substituting acetic acid and iron filings for the am- 
 monia and sulphuretted hydrogen of Zinin. 
 
 The apparatus now generally employed in the prepar- 
 ation of aniline consists of a cast-iron cylinder, of the 
 capacity of about 200 gallons, furnished with a tightly- 
 fitting cover in which there are three openings: one for the 
 introduction of the materials ; another for the exit of the 
 vapours ; whilst the third gives passage to the hollow shaft 
 of the stirrer, set in motion by bevelled wheels. The top 
 of the shaft is ground into an elbow connected with a steam 
 pipe, so that high-pressure steam can be blown through 
 perforations in the stirrer at any desired moment. In 
 order to start the operation, 20 lbs. of acetic acid (specific 
 gravity ro6o), diluted with about six times its bulk of 
 water, are introduced, and then 60 lbs. of pulverised cast- 
 iron and 250 lbs. of nitrobenzene. As soon as the stirrer 
 is set in motion, a brisk reaction ensues. The temperature 
 rises rapidly, and aqueous vapours commence to distil over 
 along with some nitrobenzene. Fresh quantities of iron 
 are introduced from time to time, until the total amounts 
 to 360 lbs., and the distillate is also repeatedly returned to 
 the apparatus. During all this time, and for at least a 
 couple of hours after the introduction of the last quantity 
 of iron, the stirrer must be kept in constant motion. 
 Steam is now blown in through the stirrer, and the aniline 
 distils over along with the aqueous vapours. 
 
 In some manufactories the acetic acid, and the whole of 
 the iron, are first introduced into the apparatus, the stirrer 
 is set in motion, and the requisite amount of nitrobenzene 
 is then allowed to flow in gradually. Instead of distilling 
 
353 DYEIXG AXD CALICO PRINTING. 
 
 the product by steam in the manner described, the semi- 
 fluid mass may be removed from the apparatus, transferred 
 to long narrow iron cylinders, and distilled over an open 
 fire. In this case the aniline always contains some 
 acetanilide. The crude product obtained by Bechamp's 
 process contains acetic acid, acetone, water, and some ben- 
 zene ; to purify it, it is redistilled ; acetone passes over 
 first, afterwards benzene, the amount of which should be 
 small, as otherwise it indicates that the operation has not 
 been properly conducted, and then dilute acetic acid. The 
 temperature now rises rapidly, and at 360° F. aniline passes 
 over. 
 
 Many other reducing agents have been proposed for the 
 conversion of nitrobenzene into aniline, such as arsenite of 
 sodium, powdered zinc, &c, but none of them have been 
 found so advantageous on a large scale as Bechamp's 
 method. In Kremer's* process, one part of nitrobenzene is 
 heated in a suitable apparatus with five of water, and two 
 to two-and-a-half of zinc dust. When the reaction is 
 completed, the aniline, amounting to about 65 per cent, of 
 the weight of the nitrobenzene, is distilled off in a current 
 of steam. The reduction both in this case, and also when 
 iron and acetic acid are used, is due to the hydrogen 
 liberated by the action of the metal on water, and may be 
 thus represented : — 
 
 C e H 5 .NO a + 3 Ha = C 6 H 6 .NHa + 2OE,, 
 
 Nitrobenzene. Aniline. 
 
 Pure aniline is a colourless, oily liquid, having a peculiar 
 spirituous odour, and pungent, aromatic taste. It is very 
 poisonous. Its specific gravity at 6o° F. is i'020, and 
 wrren submitted to a low temperature, it forms a crys- 
 talline mass, having a melting point of \j~~.6 F. : it boils 
 at 360 F. It is only slightly soluble in water, but is 
 miscible in all proportions with ether, alcohol, and benzene. 
 
 *Jour. fur Prakt. Chem., xc, 255. 
 
FORMA TION OF MA GENTA. 3 5 9 
 
 With hypochlorite of lime, it gives a bright violet-blue 
 colour, as was first observed by Runge. This phenomenon 
 occurs even with perfectly pure aniline prepared from 
 indigo. 
 
 Although magenta and the other colours derived from 
 it are known by the generic term 'aniline colours,' yet it is 
 a curious fact that this dye cannot be obtained from 
 chemically pure aniline. This discovery was made by 
 Hofmann, when endeavouring to ascertain the chemical 
 nature of magenta; he found that pure aniline when- heated 
 with arsenic acid in the manner presently to be described 
 did not yield a trace of the beautiful red dye, but, as he 
 knew that in commercial aniline there was another base 
 present called toluidine, he suspected that this, perhaps, 
 might be the true source. On repeating the experiment 
 with pure toluidine, however, equally unsatisfactory results 
 were obtained as with pure aniline ; not so, however, when 
 a mixture of the two bases was taken ; for on heating one 
 molecule of aniline and two of toluidine with a sufficient 
 quantity of arsenic acid for a short time, the whole 
 solidified to a deep red-coloured mass of nearly pure 
 magenta. 
 
 C 6 H 7 N + 2 C 7 H 9 N = Q H 19 N 3 + H 
 
 Aniline. Toluidine. Rosaniline. 
 
 From this it is evident that in order to obtain magenta, 
 which forms the basis of the greater number of the aniline 
 colours, we must have an aniline rich in toluidine. Before 
 proceeding further, therefore, it will be advisable to give a 
 short notice of the latter substance. 
 
 Toluene. — This hydrocarbon, which is the source of 
 toluidine, has the formula C 7 H 8 , and may be regarded as 
 benzene, in which one atom of hydrogen is displaced by 
 the methyl group, CH 3 . In fact, by the action of bromine 
 on benzene, we can displace one atom of hydrogen by that 
 element, forming bromobcnzenc, C c H 5 Br, and, if we mix 
 
360 DYEING AND CALICO PRINTING. 
 
 this substance with methyl iodide, CH 3 I, and treat the 
 mixture with metallic sodium, the latter combines with the 
 bromine and iodine, and toluene is formed. 
 C 6 H 5 Br + CH 3 I + Na a = C G H 5 .CH 3 + NaBr + Nal 
 
 Bromobenzene. Methyl Toluene. 
 
 Iodide. 
 
 This, however, is not the way in which the hydrocarbon 
 is prepared ; it exists ready formed in considerable 
 quantity in coal-tar naphtha, and may be obtained in a 
 tolerably pure state by treating the portion boiling between 
 220° and 240 R, with concentrated sulphuric acid, care- 
 fully rectifying, and collecting apart the portion which boils 
 at 232 F. By these means toluene is obtained as a 
 colourless, mobile liquid, very similar to benzene in appear- 
 ance and properties, but it does not solidify at-4 F., and 
 it boils at 232 F. Its specific gravity at 68° F. is 0*875. 
 
 Nitrotolueiies. — When toluene is boiled with dilute nitric 
 acid it is converted, according to Fittig,* into oxytoluic 
 acid C 7 H 6 3 , whilst fuming nitric acid attacks it with 
 great energy ; but the reaction in the latter case differs from 
 what takes place with benzene, inasmuch as not one, but 
 two mononitrotoluenes, C 7 H 7 .N0 2 , are formed. In order 
 to conduct this operation successfully, fuming nitric acid 
 (S.G. T'475) is gradually added to carefully cooled toluene, 
 until the latter is completely dissolved ; the mixture is 
 poured into a large quantity of water, and the oil which 
 sinks to the bottom thoroughly washed, so as to remove the 
 excess of acid. In order to separate the solid paranitro- 
 toluene, Rosenstiehl-f distils the mixture, and recrystallises 
 from alcohol the portion passing over above 446 F., and 
 which solidifies on cooling. Mills finds that if the crude 
 product of the action of nitric acid on pure toluene is dis- 
 tilled in a current of steam, toluene comes over first, and 
 then a mixture of paranitrotoluene with the liquid ortho- 
 
 * Ann. Chem. Pharni., cxx., 966. 
 tAnn. Chim. Phys., [iv.jxxvii., 433. 
 
NITROTOL UENES. 36 1 
 
 nitrotoluene. These two isomerides may be separated 
 very completely by cooling the mixture for half an hour to 
 o° F., and then rapidly filtering with the aid of a water 
 pump ; the liquid orthonitrotoluene has a constant boiling 
 point, and no longer yields crystals when again cooled. 
 
 Paranitrotoluene forms brilliant white crystals which 
 melt at I2 5°.6 R,* and boil at 45 9 F. It is almost 
 insoluble in water, but dissolves readily in ether, alcohol, 
 and the liquid modification of nitrotoluene. 
 
 Orthonitrotoluene. — The liquid modification above men- 
 tioned boils at 432 F, according to Beilstein and Kuhlberg t 
 It may also be prepared in a pure state from dinitrotoluene 
 by converting it into nitrotoluidine, and then treating this 
 with nitrous acid by Griess's method. 
 
 Besides the two nitrotoluenes above mentioned, obtained 
 directly from toluene by the action of nitric acid, a third 
 modification exists called metanitrotoluene. It is prepared 
 by converting solid toluidine into the acetyl compound, 
 treating this with fuming nitric acid, and after purifying 
 the product by repeated crystallisation from hot water, 
 decomposing it by boiling it with alcoholic potash. The 
 nitrotoluidine thus obtained, when treated by Griess's 
 process with strong nitric acid saturated with nitrous acid, 
 yields metanitrotoluene. It boils at 446 F., and when 
 cooled by a freezing mixture, solidifies to a mass of crystals 
 which melt at 61° F. From the results obtained by 
 Wroblevsky,*f* it would seem that this modification is also 
 present in small quantity in the mixture of nitrotoluenes, 
 obtained directly from toluene by the action of nitric acid. 
 
 Besides the mononitrotoluenes, several dinitrotoluenes, 
 and a trinitrotoluene have been obtained, but as they are of 
 no technical interest it is unnecessary to give a description 
 of them here. 
 
 * Mills, as the mean of 120 carefully made observations, finds the true 
 melting point to be 124°. 54 F. 
 
 fZeits. Chem., vii., 185. 
 
362 DYEIXG AXD CALICO PRIXTIXG. 
 
 Toluidincs. — Three modifications of toluidine, C 7 H t N, 
 or C 7 H : .XH,, are known, corresponding to the three nitro- 
 toluenes ; they may be prepared from the latter by treatment 
 with acetic acid and iron in a manner precisely similar to 
 that described when treating of the manufacture of aniline. 
 Paratoluidine crystallises from dilute alcohol in large 
 colourless plates, which are only sparingly soluble in cold 
 water, but more readily when it is hot. It is readily solu- 
 ble in alcohol, ether, benzene, and aniline. It melts at 
 1 1 y F., and boils at 3S8"-5 F. OrtJwtoluidine 'and Metatolui- 
 diiie are oily liquids, and both boil at the same temperature, 
 SS6\$ F. ; although the two bases resemble one another 
 so closely, there is a considerable difference in the physical 
 properties of the salts they form with various acids. The 
 toluidine of commerce consists chiefly of a mixture of ortho 
 and paratoluidine in varying proportion, being prepared by 
 Bechamp's process from the mixed nitrotoluenes, obtained 
 from toluene by a method similar to that employed in the 
 manufacture of nitrobenzene. 
 
 Commercial Aniline. — The liquid known in commerce as 
 aniline is not that base in a pure state, but a mixture con- 
 sisting in great part of aniline, paratoluidine (solid), and 
 orthotoluidine (liquid) in variable proportions. It also 
 contains small amounts of metatoluidine, nitrobenzene, 
 odorine, &c, but for all practical purposes it may, as just 
 stated, be regarded as a mixture of aniline and toluidine. 
 These anilines are prepared from a portion of the light 
 coal-tar naphtha, boiling between certain temperatures, by 
 treating it precisely in the manner described, first with 
 nitric acid to convert it into the nitro compounds, and then 
 reducing these with iron and acetic acid. It is evident that 
 as the coal-tar naphtha contains variable proportions of 
 benzene and toluene, the product obtained will likewise 
 contain variable proportions of aniline and toluidine. 
 Reimann, in order to distinguish the various qualities of 
 
COMMERCIAL ANILINE. 
 
 363 
 
 aniline which come into the market, takes advantage of the 
 different results obtained on submitting them to fractional 
 distillation. For this purpose 100 c.c. of the sample to 
 be tested is placed in a retort furnished with a ther- 
 mometer, and heated by means of an oil bath. The liquid, 
 as it distils, is received in a narrow, graduated cylinder, and 
 the amount which passes over between every 5° C. (9 F.) 
 noted. In order to obtain standards for comparison, he 
 first distilled a sample of light* aniline, or 'kuphaniline' as 
 he calls it, then one of heavy aniline or 'baraniline;' after- 
 wards, mixtures of the two in various proportions. The 
 accompanying table shows the results: — 
 
 CENTIGRADE. 
 
 K 100 90 
 
 85 
 
 So 
 
 75 
 
 60 
 
 5° 
 
 25 
 
 
 
 
 B 10 
 
 1 5 
 
 20 
 
 25 
 
 40 
 
 5° 
 
 75 
 
 100 
 
 Below 1S0 
 
 W 7 
 
 *Y 
 
 SY 
 
 7 
 
 ... 
 
 7 
 
 SY 
 
 
 180 - 185 
 
 54 50 
 
 29^ 
 
 22 
 
 sH 
 
 7 
 
 AY 
 
 *% 
 
 2 
 
 i8 5 °-i 9 o^ 
 
 34 34 
 
 56^ 
 
 55^ 
 
 55^ 
 
 37 
 
 lY 
 
 AY> 
 
 *% 
 
 190° -195° 
 
 ••• 5 
 
 iY 
 
 &Y 
 
 15 
 
 33 
 
 42 
 
 17 
 
 8 
 
 195° - 200° 
 
 
 
 
 9 
 
 
 J 9 
 
 36 
 
 18 
 
 200° - 205° 
 
 
 
 
 AY 
 
 16 
 
 10 
 
 16 
 
 39 
 
 205°- 2IO° 
 
 
 
 ... 
 
 
 
 0/2 
 
 8 
 
 19 
 
 2IO°- 215° 
 
 
 
 
 ... 
 
 
 
 
 AY 
 
 7 
 
 Residue. 
 
 3Y 4 
 
 4 
 
 %Y 
 
 3% 
 
 7 
 
 6% 
 
 5 
 
 sY 
 
 In order to ascertain the nature of any sample, it is only 
 necessary to distil it in the manner described, and compare 
 the results with those in the table. 
 
 MAGENTA. — This dye, although it was not the first 
 which was discovered, is, both scientifically and com- 
 mercially considered, by far the most important, forming 
 
 * The terms light and heavy as here employed are purely conventional, the 
 specific gravity of the so-called light aniline being greater than that of the 
 heavy aniline. 
 
364 DYEIXG AND CALICO PRINTING. 
 
 as it does the starting point of the greater number of the 
 other aniline colours. Natanson, in 1856, first noticed that a 
 red colour was produced from aniline, when he was examin- 
 ing the action of chloride of ethylene upon it ; two years 
 afterwards, in 1858, Hofmann, when studying the action of 
 tetrachloride of carbon on aniline, observed a magnificent 
 red coloration ; but to Verguin is due the first attempt to 
 prepare the colour on a large scale, and to employ it in 
 dyeing. On the 8th of April, 1859, he took out a patent 
 in conjunction with M. M. Renard freres, of Lyons, for the 
 manufacture of the red dye by the action of bichloride of 
 tin on aniline. In this process 20 lbs. of aniline are intro- 
 duced into enamelled cast-iron pots, capable of holding 
 about 4 gallons, and 14 lbs. of anhydrous bichloride of tin 
 are added in small portions at a time, with constant 
 stirring. As soon as all the bichloride has been added, the 
 mixture is boiled from twenty minutes to half an hour, 
 during which time the yellow fluid mass gradually changes 
 colour, and becomes almost black; the product, which is 
 soluble in water, is now poured out, and employed directly 
 for dyeing ; but it does not contain more than 5 or 6 per 
 cent, of rosaniline, the remainder consisting of aniline 
 hydrochloride, and tin salts. The operation should be con- 
 ducted under a hood, so as to carry off the irritating 
 vapours which are evolved. 
 
 The method by which Hofmann obtained aniline red has 
 been employed on the large scale by Messrs. Gerber Keller, 
 of Mulhouse; and also by Messrs. Mounet and Dury, of 
 Lyons. They heat three parts of aniline with one of tetra- 
 chloride of carbon, in closed vessels, to 350 F., for several 
 hours. A dark brownish-red mass is thus formed, which is 
 purified in a' manner similar to that which will be de- 
 scribed hereafter, when treating of the arsenic acid process. 
 
 The second process for the preparation of magenta was 
 patented in France, on the 29th October, 1859, b y Messrs. 
 
PROCESSES FOR ANILINE RED. 365 
 
 Gerber Keller, with whom were associated Messrs. Durant 
 and Schlumberger. Ten parts of aniline are heated in a 
 water bath, and seven or eight parts of mercuric nitrate, 
 dry, and in fine powder, are gradually added, with constant 
 stirring. The mass soon acquires a brown hue, and ulti- 
 mately becomes of a deep red colour, whilst the mercuric 
 salt is reduced to the metallic state, and is recovered almost 
 entirely as such. Formerly the product, as thus obtained, 
 was sent into the market under the name of 'azaleine,' but 
 it may be purified by any of the usual methods. This pro- 
 cess, which is still used to some extent in Germany, is 
 probably the most economical mode of preparing magenta 
 next to the arsenic acid . method, but the great risks which 
 the workpeople run from the frightfully poisonous character 
 of the mercury salts and mercurial vapours, render its 
 discontinuance desirable. 
 
 The process of Messrs. Lauth and Depoully consists in 
 heating to about 310 F. a mixture of one part of aniline 
 nitrate, and six or eight of aniline. Great caution must be 
 employed, as otherwise the reaction proceeds with such 
 violence that the mass inflames. After several hours' 
 heating, a deep violet-red product is obtained, containing, 
 besides rosaniline, violaniline, mauvaniline, chrysotoluidine 
 and other colours. The yield of rosaniline is only about 
 7 or 8 per cent., and the purification is very difficult. 
 
 By far the largest part of the magenta made, not only 
 for use in dyeing, but also for conversion into other aniline 
 colours, is prepared by the arsenic acid process devised by 
 Mr. Medlock, and patented by him in January, i860; a 
 French patent being taken out on the 1st of May, in the 
 same year, by Messrr Girard and de Laire. The manu- 
 facture of magenta, as it is now conducted in the large 
 colour works, is a comparatively simple process; the 
 apparatus employed consisting of a lirge cast-iron pot set 
 in a furnace, provided with means of carefully regulating 
 
366 DYEING AND CALICO PRINTING. 
 
 the heat. It is furnished with a stirrer, which can be 
 worked by hand or by mechanical means; the gearing for 
 the stirrer being fixed to the lid, so that by means of a 
 crane, the lid may be removed, together with the stirrer 
 and gearing. There is also a bent tube passing through 
 the lid for the exit of the vapours, and which can be easily 
 connected or disconnected with a worm at pleasure; lastly, 
 there are large openings at the bottom of the pot closed by 
 suitable stoppers, so that the charge can be removed with 
 facility as soon as the reaction is complete. Into this 
 apparatus which is capable of holding about 500 gallons, 
 a charge consisting of 2,740 lbs. of a concentrated solu- 
 tion of arsenic acid, containing 72 per cent, of the 
 anhydrous acid, is introduced, together with 1,600 lbs. of 
 commercial aniline. The aniline selected for this purpose 
 should contain about 25 per cent, of toluidine, for although 
 as already noticed (p. 359), Hofmann has shown that 
 rosaniline is formed from one molecule of aniline and two 
 of toluidine, by the removal of six atoms of hydrogen, 
 yet in practice, it is found that the best results are 
 obtained when a large excess of aniline is employed. 
 After the materials have been thoroughly mixed by the 
 stirrer, the fire is lighted, and the temperature gradually 
 raised to about 360° F. : in a short time water begins to 
 distil, then aniline makes its appearance along with the 
 water, and lastly, aniline alone comes over which is nearly 
 pure, containing as it does, but a very small percentage of 
 toluidine; the operation usually last's about eight or ten 
 hours, during which time about 170 gallons of liquid pass 
 over, and are condensed in the worm attached to the 
 apparatus; of this about 850 lbs. are aniline. The tempera- 
 ture should not exceed 380 F. at any period during the 
 operation. When this is complete, steam is blown in 
 through a tube provided for that purpose, in order to sweep 
 out the last traces of free aniline, and boiling water is 
 
MANUFACTURE OF MAGENTA. 367 
 
 gradually introduced in quantity sufficient to convert the 
 contents into a homogeneous liquid. When this occurs, the 
 liquid is run out at the openings at the bottom into cisterns 
 provided with agitators : here more boiling water is added 
 in the proportion of 300 gallons to every 600 lbs. of crude 
 magenta, and also 6 lbs. of hydrochloric acid. The mass 
 is then boiled for four or five hours by means of steam 
 £ipes, the agitators being kept in constant motion. The 
 solution of hydrochloride, arsenite, and arseniate of rosani- 
 line thus obtained is filtered through woollen cloth, and 
 720 lbs. of common salt added to the liquid (which is kept 
 boiling) for each 600 lbs. of crude magenta. By this means 
 the whole of the rosaniline is converted into hydrochloride, 
 which, being nearly insoluble in the strong solution of 
 arseniate and arsenite of sodium produced in the double 
 decomposition, separates and rises to the surface; a further 
 quantity is deposited from the saline solution on allowing 
 it to cool and stand for some time. In order to purify the 
 crude rosaniline hydrochloride, it is washed with a small 
 quantity of water, redissolved in boiling water slightly 
 acidulated with hydrochloric acid, filtered, and allowed to 
 crystallise. 
 
 In this process, although the greater part of the colouring- 
 matter produced is a salt of rosaniline, other aniline colours 
 are formed at the same time, notably mauvaniline, violani- 
 line, and chrysotoluidine, the amount of which is together 
 almost equal to that of the rosaniline; most of the mauvani- 
 line and violaniline, together with some of the chrysoto- 
 luidine, remain in the residues, which are insoluble in water, 
 and are separated by filtration ; the remainder of the chryso- 
 toluidine, being much more readily soluble in dilute acids 
 than rosaniline, is found in the acid mother liquors from 
 which the magenta has crystallised. The yield of pure ros- 
 aniline hydrocloride in a successfully conducted operation, 
 is from 28 to 30 per cent, of the aniline originally taken. 
 
3 6S DYEING' AND CALICO PRINTING. 
 
 Besides the method of purification just described in detail 
 there are others, in one of which, by means of an ingeniously- 
 constructed apparatus, the crude material may be dissolved 
 and filtered under pressure; in another, the free base is at 
 once extracted in the crystalline state by treating the crude 
 product with boiling milk of lime, or with boiling solutions 
 of baryta or soda. 
 
 At present, however, we have only considered the pre- 
 paration of the hydrochloride of the base, which, although 
 it can be used for dyeing, is not available for the manu- 
 facture of many of the other aniline colours. Before, 
 however, proceeding to discuss the methods by which it is 
 treated in order to obtain the free base, which constitutes 
 the starting point of the other forms in which it is used, 
 it will be advisable to glance briefly at its chemical nature. 
 
 Rosauilvie. — Hofmann has conclusively shown that all the 
 varieties of magenta obtained by the different processes 
 above mentioned, and which are so brilliantly coloured, are 
 salts of a colourless base, to which he gave the name of 
 rosaniline, and which has the composition C 20 H 19 N 3 . It 
 may readily be obtained by precipitating, with excess of 
 ammonia, a solution of any of the pure crystallised salts of 
 this base met with in commerce. If, for instance, a boiling 
 solution of the hydrochloride be employed, a reddish crys- 
 talline precipitate is produced, and the colourless liquid, on 
 cooling, deposits a further crop of crystals of the pure 
 base in colourless needles and plates, having the formula 
 C 20 H 19 N 3 ,OH 2 . 
 
 Rosaniline has a bitter taste, and when heated under 
 the surface of boiling water it melts, one thousand parts 
 of the liquid dissolving about three parts ; in boiling 
 alcohol, however, it is soluble to the extent of about ten 
 parts in one thousand. It is insoluble in ether and 
 benzene, but very soluble in aniline; when heated above 
 430 F. it ',; decomposed. Rosaniline is a triamine, and 
 
ROS ANILINE SALTS. 369 
 
 is capable of uniting with either one or three equivalents of 
 an acid to form two series of salts: the members of one 
 of these, the monacid, corresponding to ordinary magenta, 
 are stable crystalline compounds, having a brilliant, green, 
 metallic lustre, and soluble in water and alcohol, forming 
 brilliant red solutions; the other salts, the triacid, are of a 
 deep brownish-yellow colour, and far more soluble in water 
 and in alcohol than the corresponding monacid salts. 
 
 The hydrochloride of rosaniline, C, H 19 N 3 ,HC1, crystal- 
 lises in minute rhombic plates, which are only sparingly 
 soluble in water. The triacid hydrochloride, C 20 H 19 N 3 , 
 3HCI, forms brown needles, which gradually lose their acid 
 when heated to 21 2° F., being ultimately converted into the 
 monacid salt. The picrate of rosaniline forms reddish 
 iridescent needles, which are only very sparingly soluble in 
 cold water. The acetate of rosaniline, C 2 oH 19 N 3 ,C2H 4 2 , 
 which is the finest of all the rosaniline salts, issome times 
 met with in brilliant prismatic crystals, half an inch or 
 more in length, and having a beautiful, metallic, golden- 
 green iridescence. 
 
 When rosaniline, or any of its salts is heated with 
 water, in closed tubes, to a temperature of about 460 F., 
 phenol and ammonia are produced ; also a substance having 
 the properties of a weak acid, and which crystallises in 
 red needles, of the formula C 20 H 17 N 2 O.OH 2 . If, however, 
 the water used for solution has been acidulated with hydro- 
 chloric acid, the reaction is totally different, the rosaniline 
 being completely resolved into aniline and toluidine ; a 
 similar result is produced when it is heated with concen- 
 trated hydriodic acid. 
 
 As will be seen hereafter, one, two, or three of the 
 hydrogen atoms in rosaniline are capable of being replaced 
 by alcohol radicals, such as methyl, ethyl, phenyl, &c, 
 yielding new bases, the salts of which are blue and violet 
 dyes of marvellous brilliancy and intensity. 
 z 
 
370 DYEING AND CALICO PRINTING. 
 
 When any salt of rosaniline is treated with a reducing 
 agent, it takes up two atoms of hydrogen, and becomes 
 colourless, being transformed into the corresponding salt 
 of a new base, named by Hofmann leucaniline. 
 
 C 20 H 19 N 3 + H 2 = C 20 H 21 N 3 . 
 
 Rosaniline. Leucaniline. 
 
 It may easily be prepared from rosaniline hydrochloride 
 by treating it with metallic zinc and a little hydrochloric 
 acid, or still better, by the action of sulphide of ammonium: 
 a yellow resinous-looking mass is thus formed, which, after 
 being powdered, and thoroughly washed with water, is 
 dissolved in the smallest possible quantity of dilute hydro- 
 chloric acid. On adding concentrated hydrochloric acid 
 to this solution, a crystalline precipitate of leucaniline 
 hydrochloride is obtained, which may be purified by re- 
 peated solutions in the smallest quantity of water, and 
 reprecipitation by concentrated hydrochloric acid. Accord- 
 ing to Follenius,* leucaniline may be prepared from rosani- 
 line by boiling it with zinc dust and water until it is 
 completely decolorised. On cooling, the filtered solution 
 deposits the base in a crystalline state. 
 
 All the salts of leucaniline crystallise well, and the free 
 base may readily be obtained from any of them by preci- 
 pitation with ammonia. It is only sparingly soluble in 
 ether or boiling water, but readily in alcohol or an aqueous 
 solution of leucaniline hydrochloride, crystallising from the 
 latter in splendid crystals. By cautious oxidation it is 
 reconverted into rosaniline. 
 
 Hydrocyanrosaniline, C 21 H 20 N 4 . Hugo Miiller observed 
 that on treating rosaniline acetate with potassium cyanide 
 and alcohol, a yellowish-white powder was formed ; this may 
 be dissolved in dilute hydrochloric acid, and precipitated 
 by ammonia. As thus obtained, the base forms a white 
 crystalline powder, which is soluble in alcohol. It unites 
 *Moniteur Scientifique, [3] i., 678. 
 
PREPARA TION OF R OS ANILINE. 37 1 
 
 with acids to form colourless salts; the hydrochloride crys- 
 tallising readily in large monoclinic prisms, which are 
 very soluble in alcohol. 
 
 Preparation of rosaniline and its salts. — From our know- 
 ledge of the chemical nature of magenta, which is ros- 
 aniline hydrochloride, we can easily perceive that if we 
 treat it with some basic substance which has a stronger 
 attraction for hydrochloric acid than rosaniline has, the 
 strong base will combine with the acid, leaving the ros- 
 aniline in the free state. On a large scale, lime, baryta, 
 and caustic soda are all employed for this purpose, and 
 sometimes ammonia. The magenta is dissolved in a 
 quantity of boiling water sufficient to retain in solution the 
 whole of the liberated base, and a slight excess of the 
 alkali or alkaline earth is added. The mixture is now 
 boiled for several hours, filtered through woollen cloths, 
 and allowed to cool, when the free rosaniline is deposited 
 in magnificent crystals, which are almost colourless. 
 
 Unfortunately, however, rosaniline is but slightly solu- 
 ble in boiling water, so that very large quantities of liquid 
 are required. This difficulty has been obviated, and the 
 operation much facilitated, by the use of an apparatus 
 where the magenta may be decomposed and filtered under 
 a pressure of two or three atmospheres. If the rosaniline 
 hydrochloride is very pure, it is unnecessary to filter; the 
 decomposition being effected by the proper quantity of 
 caustic soda in the course of four or five hours, under pres- 
 sure, in a boiler furnished with an agitator. On allowing 
 it to cool, the contents are found to be a pulp of colourless 
 crystals, which merely require collecting and washing to be 
 ready to convert into rosaniline salts. 
 
 Acetate of rosaniline, known commercially as 'roseine,' is 
 one of the most important salts prepared from the base, 
 which for this purpose should be crystalline and free from 
 any excess of alkali. The dry powdered base (200 lbs.) 
 
372 DYEING AND CALICO PRINTING. 
 
 is introduced into enamelled iron pots, heated to about 
 1 50 F. by means of a water bath or steam heat, and pure 
 glacial acetic acid (40 lbs.), which must be quite free from 
 sulphurous or sulphuric acids, is gradually added, with con- 
 stant stirring, until a homogeneous mass is obtained of a 
 deep brick-red colour, and green metallic reflex. Boiling 
 water is now added (50 gallons) to dissolve the acetate, and 
 the mixture boiled for a few minutes, after which it is run 
 into a vat to crystallise. In the course of a few days the salt 
 is deposited in magnificent prisms, about equal in weight to 
 the rosaniline originally employed. Care must be taken 
 that the solution is not boiled for too long a time, as in 
 that case, a change takes place in the solution so that it no 
 longer gives crystals on standing. 
 
 Besides those already described, there are other processes 
 by which magenta may be prepared without the use of 
 arsenic. 
 
 Messrs. Dale and Caro, in i860, patented a method of 
 obtaining aniline red, which consisted in heating two parts 
 of aniline, with two of nitrate of lead in fine powder, to a 
 temperature of about 350° F. ; one part of phosphoric acid 
 was then gradually added to the mixture, and the whole 
 maintained at the above temperature for one or two hours, 
 with constant stirring. 
 
 Messrs. Laurent and Casthelaz, have prepared magenta 
 directly from nitrobenzene by mixing it with twice its 
 weight of iron in a fine state of division, and half its weight 
 of concentrated hydrochloric acid. After standing twenty- 
 four hours, the resinous-looking mass, which contains aniline 
 and ferric chloride, is heated, when the ferric chloride reacts 
 on the aniline, producing aniline red. The mass is ex- 
 hausted with water, and the colouring matter, which was 
 called 'erythrobenzene', precipitated by the addition of 
 common salt to the solution. It was purified by a second 
 solution and precipitation. 
 
TOLUIDINE RED. 373 
 
 More recently Coupler* has devised a process for the 
 manufacture of magenta without using arsenic acid ; he 
 heats a mixture of pure aniline, nitrotoluene, hydrochloric 
 acid, and a small quantity of finely divided metallic iron, 
 to a temperature of about 400° F. for several hours. The 
 pasty mass soon solidifies to a friable mass, resembling 
 crude aniline red ; ordinary commercial aniline and nitro- 
 benzene may be substituted for the nitrotoluene and pure 
 aniline in the above process, the products in either case 
 being extracted with water, and the colouring matter 
 precipitated with sodium carbonate. It is identical with 
 ordinary magenta, and may be purified in the usual 
 manner. 
 
 Coupier has also prepared another red, which he calls 
 toluidine red, or rosotohiidine. This may be made by mixing 
 95 parts of nitrotoluene with 65 of hydrochloric acid, and 
 then adding 67 parts of crystallised toluidine, and 7 or 8 of 
 ferric chloride. The whole is heated to 375 F. for three 
 or four hours. A product which is very similar, or perhaps 
 identical, is formed, on heating to 310 F. for four hours, 
 100 parts of liquid toluidine, 35 of hydrochloric acid, and 
 160 of a solution of arsenic acid, of 75 per cent. Analogous 
 red dyes are obtained when xylidene is substituted for 
 toluidine. 
 
 Toluidine red, possesses properties very similar to ma- 
 genta, but the shade which it gives is somewhat bluer, and 
 more intense. It is also distinguished by its salts being 
 much more soluble in water, and by the greater ease with 
 which, by proper treatment, it yields other aniline colours, 
 especially greens. The proportion of colouring matter 
 obtained from a given weight of the materials is also 
 larger, being about 40 per cent., whilst the yield of aniline 
 red seldom exceeds 30. 
 
 Mr. E. C. Nicholson took out a patent in October, 1872, 
 
 *Bull. Soc. Chim., [2] xi., 269. 
 
374 DYEING AND CALICO PRINTING. 
 
 in which he proposed to manufacture magenta by heating 
 a mixture of 3 parts of aniline with 1 of nitric acid specific 
 gravity 1*42, and 1 of hydrochloric acid, specific gravity 
 1 'i6, to a temperature of 350 — 400 F. 
 
 Jegel* has also employed a very similar process, namely, 
 to saturate 1 part of aniline with nitric acid, then to add 10 
 parts of aniline saturated with hydrochloric acid, and heat. 
 The magenta is extracted from the melted mass in the 
 usual way. 
 
 The xylidine, boiling at 414 F., prepared from coal-tar 
 naphtha, when mixed with pure aniline and treated with 
 arsenic acid, as in the manufacture of magenta, yields a 
 splendid crimson dye, which rivals that of the rosaniline 
 salts. It is a substantive colour on wool and silk. 
 
 According to Rosenstiehl,-f- crude magenta always con- 
 tains another base which he calls pararosaniline, very 
 similar to rosaniline, and isomeric with it. It appears to be 
 formed from aniline and paratoluidine, and differs from 
 rosaniline in being amorphous. When heated with hy- 
 driodic acid, it yields aniline and liquid paratoluidine, 
 instead of aniline and the crystalline toluidine. 
 
 Magenta has a most extraordinary affinity for animal 
 tissues, such as silk and wool, which readily take up the 
 colour without the intervention of any mordant; so great 
 is this attraction, that if a large skein of silk be dipped in 
 a weak boiling solution of the red dye, and quickly with- 
 drawn, the water which runs off will be found to be quite 
 colourless, the fibres of the silk removing all the colouring 
 matter from the liquid as it flows between them. This 
 property at first caused great difficulty in applying the 
 colour in silk dyeing, so as to produce an even shade, 
 especially with pale tints. It was found, however, that by 
 dyeing the silk in a weak soap bath, containing compara- 
 
 *Chem. Centr., 1874, p. 827. 
 
 fBull. Soc. Chim., [2] x., 192, and xi., 267. 
 
DYEING WITH MAGENTA. 375 
 
 tively little of the colouring matter, this obstacle could be 
 overcome to a great extent: the dyeing proceeds less 
 rapidly, and the face of the silk is kept in good condition- 
 After being thoroughly washed, the dyed silk, which has 
 been rendered soft by the action of the alkali in the soap, 
 is passed through a weak bath of acetic or tartaric acid, to 
 give it the requisite 'scroop', as the peculiar harsh sensation 
 which silk has to the touch is termed. These remarks also 
 apply to the dyeing of silk with many other of the aniline 
 colours, such as Hofmann's violet, Britannia violet, &c. 
 
 It is very important, especially in piece dyeing, that 
 there should be no particles of undissolved magenta in the 
 bath, for they would attach themselves to the fabric and 
 produce red spots. On this account it is customary to add 
 the magenta to the bath in a state of solution. Some 
 dyers dissolve it in acetic acid, but this gives it an 
 unpleasant blue shade ; a far better method is to grind up 
 the crystals with glycerin, and then boil the mixture with 
 water, and filter; this entirely prevents bronzing on the 
 surface of the tissues, and it has no flattening effect on the 
 colour. Some dyers mix the finely powdered magenta 
 crystals with spirit to a thin paste, and after allowing it to 
 stand for sixteen to twenty hours, mix it with the requisite 
 quantity of hot water, boil for a few minutes, and filter 
 through woollen cloth directly into the dyebeck. 
 
 In dyeing woollen goods with magenta, the bath is 
 generally hotter than for silk; and as acids or alkalis 
 injuriously affect the fibre, the solution must be neutral. 
 Considerable care must be taken in order to produce even 
 shades; for this purpose a part only of the total amount 
 of dye to be used is added at first, so as to form a very 
 weak liquor, in which the pieces are rapidly winced. They 
 are then lifted out of the beck, more colour added, the 
 goods re-entered and winced ; the operations being repeated 
 until the desired shade has been attained. 
 
376 DYEING AXD CALICO PRINTING. 
 
 A very simple method is sometimes adopted in dyeing 
 woollen goods. A woollen bag filter is fastened at one 
 corner of the dyebeck, the bottom of which dips a few 
 inches into the hot liquor; the quantity of magenta crystals 
 requisite to dye the pieces of the required shade is weighed 
 out, tied up tightly in a piece of flannel, and dropped into 
 the bag filter. Here the magenta slowly dissolves and 
 mixes with the liquor in the dyebeck, which never becomes 
 too strong, an important point; moreover, the solution 
 having to pass through two thicknesses of flannel, all 
 chance of any undissolved particles of the dye coming in 
 contact with the fabric is avoided. 
 
 WOOL DYED WITH MAGENTA.* 
 
 Magenta is used not merely alone for rose, pink, and red 
 shades, but also in a variety of compound colours: a 
 beautiful amaranth may be obtained on wool by the follow- 
 ing: 1 3^ ozs. of magenta are dissolved in I lb. of hot gly- 
 cerin, and the mixture filtered into the dyebeck, in which 
 8 ozs. of picric acid and 4 ozs. of soda crystals have been 
 
 * This, and the nine other beautiful specimens of woollen dyed with various 
 coal-tar colours, which occur in this work, have been most kindly furnished by 
 M. Gustave Schaeffer, of Messrs. H. Haeffely and Co., Chateau de Pfastadt, 
 near Mulhouse. 
 
PRINTING MAGENTA. 377 
 
 dissolved. These quantities give a deep shade with 20 lbs. 
 of wool. 
 
 The process of printing silk or wool is extremely simple. 
 It is merely necessary to thicken a filtered solution of the 
 colour, of the proper shade, with gum Senegal, print, dry, 
 and steam for about half an hour. The goods are then 
 washed and finished in the usual way. 
 
 Although aniline colours have a strong affinity for 
 animal substances, they merely communicate a fugitive 
 stain to vegetable fibres, which is easily removed by wash- 
 ing; moreover, being of a basic nature, the ordinary mor- 
 dants used for madder and dyewoods, such as alumina and 
 stannic oxide, are found to be of no use. Considerable 
 difficulty, therefore, was experienced at first in their appli- 
 cation to the dyeing and printing of cotton. 
 
 For dyeing cotton, a mordant is selected which varies 
 according to the circumstances of the case, as to whether 
 the tissue to be dyed consists entirely of cotton, or whether 
 it is a mixed fabric. For pure cotton, either in yarn or 
 woven, it may be prepared as for Turkey red, or it may be 
 treated by the method devised by Perkin and Pullar. It 
 is first steeped for an hour or two in a decoction of galls, 
 sumach, myrobalans, or any other substance rich in tannin, 
 and then after being allowed to drain, worked for an hour 
 or two in a weak solution of sodium stannate. It is finally 
 passed through a bath of alum or dilute sulphuric acid 
 and then rinsed in cold water. Cotton, thus prepared, has 
 a pale yellow colour, and readily takes up the magenta 
 when worked in a cold bath of that dye. Cotton may also 
 be dyed a very good and fast colour, by working it in a 
 solution of lead sub-acetate, and then in a weak soap 
 bath. 
 
 In piece dyeing, where the warp is cotton, and the weft 
 woollen, the process of mordanting is slightly varied. The 
 material is first soaked in an infusion of a tannin matter, 
 
3/3 
 
 DYEING AND CALICO PRINTING. 
 
 and then winced in a bath of tin crystals. After being 
 washed, it is ready for the dyebeck. 
 
 Calico may be printed with magenta, or any of the 
 aniline colours, by mixing the solution with albumen or 
 casein, and thickening it in the usual way with starch or 
 gum. The process of Messrs. Perkin and Schultz, also 
 gives excellent results, the colour is first printed on with a 
 thickened mixture of sodium arsenite,and aluminium acetate, 
 the proportions being — 
 
 i litre of acetate of aluminium, at i o° B. 
 
 80 grammes of arsenite of sodium. 
 
 16 „ magenta. 
 
 The pieces are then steamed for an hour, soaped, and 
 washed in pure water: by these means, very brilliant 
 shades are obtained with nearly all the aniline colours. 
 
 I 
 
 I 
 
 MAGENTA PRINTED ON COTTON.* 
 
 A fine purple may be obtained on cotton, by steeping it 
 for a couple of hours in a hot bath containing 3lbs. of 
 turmeric, and lib. of sumach. lib. of sulphuric acid is then 
 added, the yarn worked in the mixture, taken out, and 
 
 *This, and the seven other splendid samples of aniline colours printed on 
 calico, which are interspersed throughout this portion of the work, have been 
 generously placed at our disposal by M. Horace Koechlin, of Wisserling, Alsace. 
 
AD ULTERA TION OF MA GENTA. 379 
 
 washed. Cotton thus mordanted, has a yellow colour, and 
 acquires a fine purple shade when worked in a magenta 
 bath. 
 
 Adulteration of Magenta. — The presence of any 
 of the foreign colours, violaniline, mauvaniline, or chryso- 
 toluidine, may be readily ascertained by dissolving the 
 suspected sample in the smallest possible quantity of 
 alcohol, diluting with rather more than its own bulk of 
 water, and then putting a drop of the liquid on a piece of 
 white blotting paper. The spot formed by the capillary 
 action of the paper will present concentric circles of 
 different tones of colour if the magenta is not pure. 
 This simple method may also be applied to the examination 
 of aniline blues and violets. 
 
 As in the case with the madder dyestuffs, one of the best 
 methods of testing magenta, both for the purity of tone 
 and also for the amount of colouring matter, is to make a 
 comparative dyeing experiment with the sample under 
 investigation, and with one of known purity, using white 
 woollen yarn. 
 
 Crystallised magenta is sometimes adulterated to a large 
 extent with sugar which has previously been dyed with 
 magenta. On spreading out such a sample on a sheet of 
 white paper in the sunshine, the larger crystals of dyed 
 sugar may readily be detected by their colour being paler 
 at the edges. When picked out and washed with alcohol, 
 they become colourless, and the odour of caramel which is 
 produced when they are heated is sufficient to identify 
 them. The amount of this adulteration may be deter- 
 mined by washing a weighed quantity of the sample with 
 absolute alcohol until colourless, or nearly so, and then 
 drying and weighing the residue, or more accurately by 
 dissolving a weighed portion of the dye in hot water, and 
 precipitating the rosaniline as picrate by means of picric 
 acid. The clear yellow solution is now precipitated with 
 
380 DYEIXG AXD CALICO PRIXTIXG. 
 
 basic acetate of lead, filtered, the excess of lead thrown 
 down by sulphuretted hydrogen, and the amount of sugar 
 present estimated by means of the polariscope. 
 
 There are several other aniline reds met with in com- 
 merce besides magenta, the most important of which are 
 safranine, geranosine, ponceau, and Ulrich's scarlet. 
 
 SAFRANINE, OR SAFFRANINE, is a bright rose-coloured 
 dye, which, according to Mene, is prepared commercially by 
 treating heavy aniline oils successively with nitrous acid 
 and arsenic acid, or two parts of the aniline may be heated 
 with one of arsenic acid and one of an alkaline nitrate 
 for a short time, to 20CT or 212° F. The product is ex- 
 tracted with boiling water, neutralised with an alkali, 
 filtered, and the colour precipitated with common salt. It is 
 met with both in the state of paste, and also as a yellowish- 
 red powder, which contains the hydrochloride of the base 
 mixed with calcium carbonate and common salt. On boil- 
 ing this with water, filtering, and acidulating the filtrate 
 with hydrochloric acid, a crystalline substance separates on 
 cooling, which, after repeated crystallisation in a similar 
 manner, no longer leaves any residue on ignition. The 
 addition of hydrochloric acid to the filtrate is necessary, as 
 otherwise it is found to lose acid by repeated crystallisation, 
 and to become much more soluble. 
 
 Pure safranine hydrochloride, C 21 H 20 N 4 ,HC1, forms thin 
 reddish crystals which are soluble in water and in alcohol, 
 yielding intensely yellow-red solutions. The free base 
 safranine may be obtained from this by decomposing the 
 solution with silver oxide, and evaporating the deep-red 
 liquid. It forms reddish-brown crystals, which are very 
 soluble both in alcohol and in water. 
 
 Hofmann and Geyger,* who have carefully investigated 
 the subject, find that safranine cannot be prepared either 
 from pure aniline or pure crystalline toluidine, or from a 
 * Deut. Chem. Ges. Ber., v. 526. 
 
PRINTING WITH SAFRANINE. 
 
 38l 
 
 mixture of the two, but that it is derived from the liquid 
 toluidine, boiling at 389 F., the reactions being as follow: — 
 3 C 7 H 9 N + HNO a = C^H^ + 2 OH 2 
 CnH^N, + 2 = CaHaoNi + 2 OH 2 
 The action of nitrous acid first produces the compound 
 C 21 H 21 N 4 , which is then converted by the action of the 
 oxidising agent into safranine. They find, however, that 
 when arsenic acid is employed for this latter purpose, the 
 safranine is mixed with a large amount of secondary pro- 
 ducts. This may be avoided to a great extent by substi- 
 tuting chromic acid for arsenic acid as the oxiding agent. 
 
 The most characteristic reaction of safranine is, that when 
 concentrated sulphuric acid is gradually added to its 
 solutions, the colour first changes to violet, and then passes 
 successively to blue, dark green, and light green ; on now 
 diluting the solution with water, the same changes of colour 
 will be observed, but in the reverse order. 
 
 SAFRANINE. 
 
 Safranine may be printed by thickening the paste with 
 
 twenty parts of a mixture consisting of — 
 
 Acetate of alumina standard 1 gallon 
 
 "Water 1 „ 
 
 Starch 2 lbs. 
 
 Boil, and when cold add 1 pint of arsenic standard. 
 
3 S2 DYEIXG AXD CALICO PRINTING. 
 
 The acetate of alumina standard is the clear liquid 
 obtained on precipitating a solution of 5 lbs. of alum in 2 
 gallons of water, with 6 lbs. of lead acetate, and allowing 
 to settle. 
 
 The arsenic standard is made by boiling 4 lbs. of arseni- 
 ous acid (white arsenic) in 1 gallon of glycerin, until 
 dissolved, and then filtering. 
 
 After printing, the goods are steamed for half an hour. 
 
 Safranine is now superseding safflower, or carthamine, 
 as a red dye for silk. It requires no mordant. 
 
 GERAXOSINE. — This is a beautiful ponceau red, obtained 
 from rosaniline by a process devised by Luthringer. To 
 prepare it 2 lbs. of magenta are dissolved in 200 gallons of 
 boiling water, and as soon as it has cooled down to 1 1 3 F., 
 a solution of 9 lbs. of barium or calcium nitrite in 7 gallons 
 of water is poured in (peroxide of barium may be substi- 
 tuted for the nitrite if thought desirable). As soon as 
 the two liquids are throroughly mixed, 20 lbs. of concen- 
 trated sulphuric acid are added. The liquid instantly 
 becomes yellow, and in a few moments colourless ; it is now 
 filtered from the precipitated barium sulphate and gradually 
 heated to the boiling point. The liquid, which thus 
 acquires an intense red colour, is boiled for two or three 
 minutes, allowed to cool, and the colouring matter preci- 
 pitated by common salt. 
 
 PONCEAU. — This is a colour manufactured by Messrs. 
 Brooke, Simpson, and Spiller, by a secret process. It is a 
 very brilliant red, and retains its colour when seen by arti- 
 ficial light. It dyes wool and silk without a mordant, the 
 only precaution necessary being to add the colour very 
 gradually to the bath, and so work slowly up to the re- 
 quired shade. The addition of a little ammonia to the 
 bath varies the hue. 
 
 CERISE. — This is the name given to a colour manu- 
 factured by Knosp, of Stuttgard, from magenta residues, 
 
ULRICH'S SCARLET. 383 
 
 and is probably a mixture of rosaniline and chrysotoluidine. 
 It is thrown down on adding carbonate of soda to the 
 mother liquors obtained in the manufacture of magenta 
 after that colour has been precipitated by common salt. It 
 dyes wool and silk scarlet shades. 
 
 Ulrich's Scarlet. — This is a compound obtained by 
 the partial oxidation of magenta. To prepare it, a solution 
 of three parts of lead nitrate, dissolved in the smallest 
 possible quantity of boiling water, is mixed with four parts 
 of powdered rosaniline acetate, and the whole evaporated to 
 dryness at a gentle heat. The dry mass is now heated 
 gradually to a temperature varying from 300 to 400 R, 
 when it becomes violet. The product, as soon as it is cold, 
 is extracted by boiling with very dilute sulphuric acid. 
 The solution is then neutralised, filtered boiling hot, and 
 the colour precipitated in the usual way with common salt. 
 
 This scarlet yields a rose-red dye when heated under 
 pressure with alcohol, and methyl or ethyl iodide, as in the 
 process for preparing Hofmann violet. It is purified in a 
 similar manner to that colour. 
 
CHAPTER XIII. 
 
 ANILINE VIOLETS. — ANILINE BLUES. 
 
 Aniline Violets. — The most important of these from 
 a scientific and historical point of view is mauve, or aniline 
 purple, discovered by Mr. W. H. Perkin, and patented by 
 him in August, 1856.* Not only was this the first dye 
 made from aniline which received any practical application, 
 but the brilliancy and beauty of the new colour, as com- 
 pared with those hitherto obtained, excited universal atten- 
 tion, so that the investigation of the nature of the aniline 
 derivatives was pushed forward with great vigour. The 
 result was the establishment of an entirely novel branch of 
 manufacture, which has since developed to such an 
 enormous extent, not only in the production of the various 
 'coal-tar colours,' but, as we have already seen, in the arti- 
 ficial production on a manufacturing scale of alazarin, a 
 dye which was formerly only obtained from the root of the 
 madder and other plants. 
 
 Mr. Perkin's own account of his discovery, as related 
 before the Society of Arts, is as follows : — 
 
 "Chemists have always been desirous of producing natural 
 organic bodies artificially, and have, in many instances, 
 been successful. It was whilst trying to solve one of these 
 questions that I discovered the ' mauve.' I was endeavour- 
 ing to convert an artificial base into the natural alcaloid 
 quinine, but my experiment, instead of yielding the colour- 
 less quinine, gave a reddish powder. With a desire to 
 understand this peculiar result, a different base of more 
 
 *No. 1984. 
 
MANUFACTURE OF MAUVE. 385 
 
 simple construction was selected, namely, aniline, and in 
 this case I obtained a perfectly black product : this was 
 purified and dried, and when digested with spirits of wine 
 gave the mauve dye." 
 
 This dye is prepared by the action of oxidising agents 
 on an aqueous solution of a salt of aniline. The nature of 
 the aniline is a very essential point, for it has been found 
 that, that which gives the best results for magenta is not at 
 all suitable for the production of mauve. The process 
 generally adopted for its manufacture is that originally 
 devised by Perkin : — 108 lbs. of sulphuric acid are diluted 
 with 4 lbs. of water, and when cool the mixture is gradually 
 poured into 200 lbs. of suitable heavy aniline, with constant 
 stirring. When all the acid has been added, the mixture 
 is heated, and stirred, so as to render it homogeneous, and 
 then allowed to cool ; 280 lbs. of potassium dichromate 
 are then dissolved in the smallest possible quantity of 
 water, and stirred into the mixture, allowing the whole to 
 stand twenty-four hours. At the expiration of this time, 
 the liquid, which at first was turbid, has become quite clear, 
 the impure mauve being found at the bottom of the vessel 
 as a black precipitate. The supernatant liquor is now 
 drawn off, and the precipitate thoroughly washed three or 
 four times by stirring it up with boiling water ; it is after- 
 wards washed with water acidulated with sulphuric acid, 
 and finally with cold water. The colouring matter is 
 extracted from the precipitate by boiling it with water for 
 about three hours, decanting and filtering: the process 
 being repeated until no more colouring matter is dissolved. 
 An alkali, or alkaline carbonate is added to the aqueous solu- 
 tion thus obtained, in order to precipitate the base wauveine, 
 which is collected, washed with warm water, and dissolved 
 in the requisite quantity of acetic acid. In order to obtain 
 the base in a tolerably pure state, the processes of solution, 
 precipitation, and washing must be repeated several times. 
 AA 
 
386 DYEING AND CALICO PRINTING. 
 
 When mauve was first manufactured, the crude product 
 was purified by washing and drying it, and then treating it 
 in closed vessels with boiling coal-tar naphtha to remove 
 resinous impurities. After this, it was exhausted with 
 dilute spirit, the spirit distilled off, and the aqueous solution 
 of the colouring matter which was left, filtered and precipi- 
 tated with caustic soda. The loss of valuable solvents, and 
 the danger in manipulating with large quantities of 
 inflammable liquids caused this process to be superseded by 
 that just described. 
 
 On dissolving the purified mauve in boiling alcohol and 
 acetic acid, a solution may be obtained which deposits the 
 acetate of mauveine in the crystalline state. It may be 
 purified by one or two crystallisations, when it has a 
 splendid green metallic lustre. It is occasionally met with 
 in commerce in this state, but more generally in paste, or 
 in solution, as the crystals are costly, and do not offer any 
 corresponding advantage to the consumer. 
 
 The base maiiveine, C 2G H 24 N 4 , unlike rosaniline, is not 
 colourless, but of a dingy violet colour. It may readily be 
 obtained by dissolving a pure salt of the base in boiling 
 alcohol, and adding a slight excess of an alcoholic solution 
 of potash : on cooling, it is deposited in black glistening 
 crystals not unlike specular iron ore in appearance. 
 Mauveine is a very powerful base, readily expelling am- 
 monia from its salts when boiled with them. It is almost 
 insoluble in benzene, and in ether, but dissolves to some 
 extent in alcohol, forming a dingy violet-blue solution : the 
 addition of an acid immediately changes this to a deep 
 purple, resulting from the formation of a salt of mauveine. 
 The sulphate and hydrochloride of mauveine may both be 
 obtained in the crystalline state; the former is the original 
 aniline purple, formed by the action of potassium di- 
 chromate on aniline sulphate. The salts of mauveine are 
 generally very hydroscopic ; they are only slightly soluble 
 
PHCENICINE. 387 
 
 in cold water, somewhat more so in boiling water, and 
 readily soluble in alcohol and wood spirit. When sub- 
 mitted to the action of nascent hydrogen, mauveine takes 
 up hydrogen, and becomes converted into a new base, the 
 salts of which are colourless, or nearly so. This may be 
 well illustrated by boiling an alcoholic solution of mauve 
 with a few strips of zinc in a tube, which is imperfectly 
 closed, when the dark purple of the solution gradually 
 changes to yellow. On exposure to the air, however, it 
 rapidly acquires its original purple colour. 
 
 Perkin has found that in the formation of mauve or 
 aniline purple, there is always a small quantity of a second 
 colouring matter produced, which gives rich crimson or rose 
 shades, similar to those from safBower. It occurs, however, 
 but in small quantity. When pure, it crystallises in small 
 prisms possessing a beautiful golden-green lustre. It is 
 soluble both in water, and in alcohol, yielding solutions re- 
 markable for their fluorescence, so much so, that in certain 
 lights the clear transparent liquid appears turbid. 
 
 Phcenicine is a ponceau red dye, discovered by Willm 
 in 1 86 1, who prepared it by boiling a solution of mauveine 
 in acetic acid, with barium peroxide, until the red colour was 
 fully developed. The liquid is then poured out and care- 
 fully neutralised with carbonate of soda. The colour 
 may be thrown down from the filtered liquid by means of 
 common salt. 
 
 It is not improbable that this red is identical with that 
 described by Delvaux, as obtained by the action of chromic 
 acid on aniline: 1 part of chromic acid is dissolved in 20 
 of water, and 1 part of aniline is added. After standing 
 for twenty-four hours, the black precipitate which is pro- 
 duced is exhausted with boiling water, and the filtered 
 solution rendered alkaline with ammonia. Aniline purple 
 is then thrown down, whilst a red colouring matter remains 
 in solution. 
 
388 DYEING AND CALICO PRINTING. 
 
 Mauve has also been manufactured in France by the 
 action of hypochlorite of lime on a solution of a salt 
 of aniline. Perkin has investigated this reaction, and 
 finds that the blue colour observed many years ago by 
 Runge, on adding a solution of hypochlorite to one of ani- 
 line, is not due to mauve, but to a distinct substance of a 
 blue colour. On mixing solutions of aniline hydrochloride 
 and calcium hypochlorite (chloride of lime) the solution 
 gradually becomes turbid from the formation of a finely 
 divided indigo-blue precipitate. On adding common salt 
 this new substance is precipitated. It is, however, very 
 impure, and requires treatment with ether or benzene to 
 remove brown- coloured resinous substances. Runge's blue, 
 as thus prepared, is a solid substance, which dissolves in 
 alcohol with a fine blue colour, and is capable of dyeing 
 silk of a blue colour ; it is, however, very unstable, the 
 colour of the alcoholic solution changing to purple in a day 
 or two at the ordinary temperature, and immediately if 
 heated. The same effect is observed on the dyed fabric. 
 In the process of manufacture adopted in France, the 
 product is boiled so as to convert it into mauve. In 
 Messrs. Depouilly and Lauth's patent, taken out in 
 June, i860, the precipitate formed by the addition of a 
 solution of chloride of lime to a solution of aniline 
 hydrochloride was washed with acidulated water, dis- 
 solved in concentrated sulphuric acid, and reprecipitated 
 by water. The amount of product obtained by this 
 method is said to be larger than when Perkin's process 
 is employed, but the shades obtained in dyeing are not 
 so pure. 
 
 About this time several other processes were patented 
 for the production of mauve by the action of various 
 oxidising agents on aniline. In January, i860, Mr. Kay 
 proposed to manufacture mauve by heating a solution of 
 aniline sulphate with manganese peroxide (black oxide of 
 
OTHER PROCESSES FOR MAUVE. 389 
 
 manganese) to 21 2 , and, when the reaction was complete, 
 precipitating the colour with an alkali. 
 
 Mr. C. Greville Williams also patented the production of 
 a purple dye by oxidising aniline with potassium perman- 
 ganate; and in the latter part of the year 1859 Mr. David 
 Price took out a patent for the manufacture of aniline 
 purple, by boiling a solution of one molecule of aniline 
 sulphate with two of lead peroxide; the solution of the 
 colouring matter thus obtained was filtered, concentrated 
 by evaporation, and, after a second filtration, precipitated 
 by an alkali. According to Dollfus,* Messrs. Frank & Co., 
 of Lyons, and Messrs. Griiner & Co., Glauchau, in the year 
 1859, succeeded in obtaining a reddish-violet colour by 
 treating a solution of magenta in wood spirit with potassium 
 dichromate and sulphuric acid. This process, which was at 
 first a secret, afterwards became generally known. The 
 nature of the reaction which takes place in the production 
 of this colour has not been ascertained, but it is well known 
 that if magenta is dissolved in wood spirit it yields on 
 fabrics a much bluer shade than when water or alcohol is 
 employed as the solvent. 
 
 In May, iS6o,*f" Messrs. Dale and Caro patented a pro- 
 cess for preparing aniline purple, differing from that of Mr. 
 Perkin, the oxidising agent employed being cupric chloride. 
 One equivalent of a neutral salt of aniline is mixed with 
 six equivalents of chloride of copper, dissolved in water 
 (thirty times the weight of the aniline salt), and the whole 
 boiled for three or four hours. The dark coloured precipi- 
 tate is purified by processes similar to those employed in 
 treating the product obtained by Perkin's method. A 
 mixture of common salt and sulphate of copper, in equiva- 
 lent proportions, may be substituted for the cupric chloride. 
 
 In January, 1861, M. Girard took out a patent for 
 
 * Wagner's Jahresbericht, xx., 794. 
 fNo. 1307. 
 
390 DYEING AND CALICO PRINTING. 
 
 preparing ' Violet Imperial' by heating a mixture of equal 
 weights of magenta and aniline to 330 F. for several hours. 
 The purple-coloured mass after being washed with water 
 and hydrochloric acid, to remove any unaltered aniline or 
 magenta, is ready for use. It is readily soluble in alcohol, 
 acetic acid, and wood spirit. This dye, which was long re- 
 garded as a compound of magenta and aniline blue, has 
 been shown by Hofmann to consist of a mixture of salts 
 of monopJienylrosaniline, C 20 H 18 (C 6 H 5 )N 3 , and diphenylros- 
 aniline, C 20 H 17 (C 9 H 5 ) 2 N 3 identical with those obtained 
 in the manufacture of aniline blue, when an insufficient 
 quantity of aniline has been employed. 
 
 Monophenylrosaniline salts are of a reddish-violet colour, 
 and may be prepared as follows: 80 lbs. of aniline, and 20 
 of rosaniline sulphate or hydrochloride, both in a perfectly 
 dry state, are heated in an apparatus similar to that em- 
 ployed for the manufacture of aniline, gently for the 
 first half-hour, after which the temperature is raised, but 
 should never exceed 375 ° F. The progress of the action 
 must now be tested every five minutes by withdrawing a 
 small portion of the material by means of a glass rod, and 
 transferring it to a white porcelain plate, where it is mixed 
 with a little alcohol and acetic acid. The operation is in- 
 terrupted immediately the colour is observed to be of a pure 
 red-violet tint; and as soon as the contents of the vessel are 
 cool enough, they are poured in a very thin stream into a 
 vessel containing an acidulated solution of common salt, 
 which is kept violently agitated by mechanical means. 
 The impalpable powder thus obtained is purified by wash- 
 ing it thoroughly, first with a similar solution, and then with 
 pure water; after being pressed and dried at a low tempera- 
 ture, it is fit for the market. Another method of purification 
 consists in pouring it into benzene, dissolving the precipitate 
 in the smallest quantity of concentrated hydrochloric acid, 
 and then largely diluting with water: the violet is thus 
 
PHENYLROSANILINE VIOLETS. 391 
 
 precipitated, whilst the unaltered magenta remains in 
 solution. 
 
 Diphenylrosaniliue salts are of a much bluer tinge than 
 the corresponding monophenylated compounds. The 
 method of preparation is very similar, but the time of 
 heating is longer, and rosaniline acetate is employed in- 
 stead of the sulphate or hydrochloride; 20 lbs. of the acetate 
 to 40 of aniline, giving good results. The product is 
 poured into about 80 gallons of alcohol, which is then 
 acidulated with hydrochloric acid, and the violet dye 
 precipitated by means of a saturated aqueous solution of 
 common salt. It now merely requires to be washed once 
 or twice with acidulated water, and finally with pure water. 
 
 In preparing these phenyl violets, Levinstein employs 100 
 parts of magenta, 100 of aniline, and 25 of acetate of soda, 
 for the red shades ; and 3 parts of aniline to 1 of magenta 
 for the blue shades. In the production of very blue violets, 
 soap is often used, the heat being continued for a consider- 
 able time: 300 parts of magenta, 100 of aniline, 75 
 of sodium acetate, and 66 of white curd soap is a mixture 
 which gives good results. The excess of aniline may be 
 removed by boiling the product with very dilute hydro- 
 chloric acid, and the dye which floats on the surface, is 
 skimmed off, washed, dried, and powdered. 
 
 These violets are soluble in alcohol, acetic acid, and 
 glycerin, but their employment is comparatively limited 
 since the discovery of the Hofmann and Paris violets, 
 which are methylated or ethylated rosaniline salts. 
 
 Mr. G. C. Nicholson in 1862, took out a patent for the 
 preparation of ' ' Rcgina purple', by the following process : 
 "I take red dye, such as is made from aniline or its homo- 
 logues and, without the admixture of either aniline, or its 
 homologues, I heat it carefully, in a suitable apparatus, to 
 a temperature by preference between 390 and 420° F. 
 The substance quickly assumes the appearance of a dark 
 
392 DYEING AND CALICO PRINTING. 
 
 semi-solid mass, the red dye being transformed into a dark 
 substance with evolution of ammonia. The mass I prefer 
 afterwards to extract with acetic acid, using a quantity 
 of acid about equal in weight to the amount of the red 
 dye treated, and this acid I dilute with enough alcohol to 
 make a dye of convenient commercial strength ; the solution 
 obtained is of a deep violet or purple colour, and may be 
 used directly for dyeing purposes." 
 
 Kopp's violet L Is prepared by grinding up rosaniline tannate 
 to a paste with three or four times its weight of wood 
 spirit, and then adding about one-twentieth of its volume 
 of nitric or hydrochloric acid, or better, of a saturated alco- 
 holic solution of hydrochloric acid. The red colour of the 
 mixture gradually acquires a violet tinge, which, on stand- 
 ing, becomes more and more defined, and then passes into 
 a nearly pure blue. By properly regulating the amount of 
 acid, any desired shade may be obtained. When the pro- 
 duct is dry, it merely requires washing with water to 
 remove the excess of acid in order to be ready for use. It 
 should be dissolved in alcohol, or wood spirit, and the 
 liquid diluted with water. 
 
 A violet may also be obtained mixed with Prussian blue 
 and other extraneous matters, by boiling for half an hour 
 a mixture of equal equivalents of potassium ferrocyanide 
 (red prussiate) and a salt of aniline, dissolved in 20 parts of 
 water. Potassium ferrocyanide remains in solution, and a 
 precipitate is produced, which is first treated with coal oil 
 to remove brown resinous matters, after which the violet 
 colouring matter may be extracted by boiling alcohol. 
 
 Mauvaniline and Violcuiiline. It has been already 
 noticed (p. 367) that in the preparation of magenta three 
 other colouring matters are produced, namely, mauvaniline, 
 violaniline, and chrysotoluidine, which in great part remain 
 undissolved when the crude magenta is treated with water. 
 These residues, which amount to nearly one-half of the 
 
HOFMANN VIOLETS. 393 
 
 total products of the reaction, were formerly regarded as 
 useless ; but Paraf, and subsequently Girard and De Laire, 
 have succeeded in separating the bases, and rendering them 
 available for dyeing purposes. In order to effect this, the 
 insoluble residue is first boiled with caustic soda, in order 
 to obtain all the bases in the free state; these are now 
 treated with dilute hydrochloric acid, which dissolves the 
 chrysotoluidine and mauvaniline, and leaves the violaniline. 
 On adding common salt to the hydrochloric acid solution, 
 mauvaniline hydrochloride is precipitated, whilst chryso- 
 toluidine salt remains in solution. Mauvaniline may be 
 obtained in crystals having the formula C 19 H 17 N 3 ,OH 2 , 
 which are insoluble in water, but soluble in alcohol, ether, 
 and benzene. Its salts are soluble in water, and yield fine 
 red-purple tints on fabrics. The colours produced by viol- 
 aniline are dull and little used. 
 
 MetJiyl and etliyl-rosanilines. — It has been already stated 
 that Hofmann, when engaged in investigating the nature of 
 rosaniline, discovered that it was a triamine in which there 
 were three equivalents of hydrogen capable of being re- 
 placed by alcohol radicals. In fact, he found on heating it 
 with excess of ethyl iodide for some hours to 21 2° in closed 
 tubes, that a magnificent purple substance was produced, 
 which was the iodide of a new base, tricthylrosaniline C 20 H 16 
 (C 2 H 5 ) 3 N 3 ,or rosaniline C, H 19 N 3 , in which three of the 
 hydrogen had been replaced by three ethyl groups, C 2 H 5 . 
 By varying the circumstances of experiment, instead of 
 three of the hydrogen being replaced by ethyl, dyes 
 may be obtained having two, or only one, replaced by 
 ethyl ; moreover, by substituting methyl iodide for ethyl 
 iodide, corresponding methyl compounds may be prepared. 
 In this way Hofmann violets are obtained of different 
 shades, varying from RRR, the very red, which is principally 
 a salt of monomethylated rosaniline C 28 H 1S (CH 3 )N 3 , to 
 BBB, the bluest shade. 
 
394 DYEIXG AND CALICO PRINTING. 
 
 For the red-violet RRR. 
 
 Rosaniline 20 lbs. 
 
 Alcohol 200 „ 
 
 Hydrate of potassium or sodium 20 ,, 
 
 Iodide of methyl or ethyl 16 „ 
 
 HOFMAXX VIOLET. RRR. 
 
 For a blue-violet B. 
 
 Rosaniline 20 lbs. 
 
 Alcohol 200 „ 
 
 Hydrate of potassium or sodium 20 ., 
 
 Iodide of methyl 10 „ 
 
 Iodide of ethyl 10 ,, 
 
 HOFMAXX VIOLET. B. 
 
MANUFACTURE OF HOFMANN VIOLET. 395 
 
 For a bluer shade BB. 
 
 Rosaniline 20 lbs. 
 
 Alcohol 200 „ 
 
 Hydrate of potassium or sodium 20 „ 
 
 Iodide of methyl 40 „ 
 
 These violets are now made in enamelled iron autoclaves 
 of a capacity of about 18 or 20 gallons, and capable of sus- 
 taining a pressure of 300 to 400 lbs. on the square inch. 
 They are fitted with a thermometer and a pressure gauge, 
 and are heated by means of a water bath or steam jacket. 
 The preceding are the proportions given by Girard and 
 De Laire. 
 
 The rosaniline and a portion of the alcohol are intro- 
 duced into the apparatus, and heated with part of the 
 iodide; the potash in alcoholic solution, and the iodide 
 being added alternately, in successive portions, during the 
 operation ; this takes about two hours, the temperature 
 being 240 to 265 ° F. When the required shade is attained, 
 the contents of the boiler are drawn off and purified. With 
 methyl iodide the product is bluer and more soluble in 
 water than when the corresponding ethyl compound is 
 employed. 
 
 In order to purify the crude product and recover the 
 iodine, the colouring matter, after the separation of the 
 excess of alcoholic iodide by distillation, is treated with a 
 hot alcoholic solution of soda in an apparatus provided 
 with a cohabator and an agitator. The precipitated base, 
 after being thoroughly washed with boiling water, is treated 
 with sulphuric, hydrochloric, or acetic acid, and the result- 
 ing salt dissolved in boiling water and precipitated with 
 common salt or sodium acetate. These aniline violets are 
 readily soluble in alcohol and in water, and may be ob- 
 tained in the crystalline state. 
 
 Although the free base, rosaniline, is generally used in the 
 preparation of these colours, it is not absolutely essential. 
 
396 DYEING AND CALICO PRINTING. 
 
 Very good results may be obtained by heating together 
 rosaniline acetate, methyl iodide, and alcohol, or wood 
 spirit : in fact, Hofmann's violets are frequently made in 
 this way in Germany. The action, however, takes place 
 with less facility, so that a higher temperature and a longer 
 time are required. 
 
 The Hofmann violets are remarkable for the brilliancy 
 of their colour, but unfortunately they do not resist the 
 action of light so well as many other of the aniline colours — 
 this is especially the case on cotton. It is generally the 
 case that aniline colours resist light better when applied to 
 animal fibres, such as silk or wool. 
 
 In the formation of these colours it will be observed that 
 as more and more of the hydrogen in the red magenta is 
 replaced by methyl or ethyl, the bluer is the shade of violet 
 produced. With mauve, however, the effect is exactly the 
 reverse, the shade produced by the salts of the new 
 ethylated or methylated base being redder than that of the 
 original dye. A colour intermediate between aniline 
 purple and magenta, and known as ' dahlia,' is prepared in 
 a similar manner to the Hofmann violets by the action of 
 alcohol and iodide of ethyl on mauveine. This colour 
 possesses the same character for fastness as mauve, but 
 unfortunately it is rather expensive, and therefore is not 
 used very extensively. 
 
 Instead of preparing magenta by the action of oxidising 
 agents on a mixture of aniline and toluidine, and then re- 
 placing one or more equivalents of the hydrogen in this 
 base by an alcohol radicle, such as ethyl or methyl, in 
 order to obtain these violet dyes; we may first introduce 
 the alcohol radicle into the aniline and toluidine, and then 
 submit the methylaniline and methyltoluidine thus formed 
 to the action of oxidising agents. It is in this way that 
 the so-called 'Paris violet' is prepared. 
 
 The first step in the manufacture of this dye is the pre- 
 
PARIS VIOLET. 397 
 
 paration of methylaniline, which in the pure state has the 
 composition C 7 H 9 N or C 6 H G (CH 3 )N. being aniline in 
 which one atom of hydrogen is replaced by the methyl 
 group CH 3 . As produced on the large scale, however, 
 from commercial aniline, which is a mixture of aniline and 
 toluidine, it is, of course, a mixture of methylaniline and 
 methyltoluidine. Both the iodide and bromide of methyl 
 combine with aniline most energetically, producing methyl- 
 aniline hydriodide, or hydrobromide, from which the free 
 base may be liberated by means of a caustic alkali. The 
 high price of both bromine and iodine, however, is an 
 obstacle in the way of the adoption of this process, and 
 other methods have been devised by which the base may 
 be more conveniently obtained. On heating to about 550 
 R, for twelve hours, a mixture of 60 or 80 parts of wood 
 spirit, and 100 of aniline hydrochloride, the latter becomes 
 converted into the corresponding methylaniline salt. A 
 similar result is produced by heating to 570 F., 100 parts 
 of aniline, 80 of wood spirit, and 100 of ammonium chloride. 
 The aniline may also be treated with methyl nitrate, or 
 methyl chloride, either at the ordinary temperature, or at 
 212 F. under pressure. In any case the salts produced 
 are decomposed by caustic soda, and the oily mixture of 
 methylaniline and dimethylaniline is distilled in a current 
 of steam, and then rectified in an oil bath, collecting apart 
 the portion which boils above 410 F. 
 
 The Paris violet was discovered by M. C. Lauth, but the 
 processes have since been much improved by Messrs. 
 Poirrier and Chappat. Lauth heats salts of methylaniline 
 and dimethylaniline, such as the hydrobromide or hydro- 
 chloride, either with sand, or with certain oxidising agents 
 such as cupric nitrate or chloride, mercuric acetate, &c. 
 Poirrier's process consists in gradually adding 5 or 6 parts 
 of anhydrous stannic chloride to I of methylaniline in 
 successive portions, and then heating the mass to 21 2° F. for 
 
398 D YEING AND CALICO PRINTING. 
 
 several hours, until it becomes hard and brittle. When cold 
 it is washed and boiled with a solution of caustic soda, 
 which removes the tin, and leaves the base in a free state. 
 This is then taken up with the equivalent quantity of 
 hydrochloric or acetic acid, and the solution evaporated to 
 dryness at a gentle heat. A bronzed mass is left, which is 
 very soluble in water, alcohol, and acetic acid. Instead of 
 stannic chloride other oxidising agents may be used, as is 
 shown by the following methods which have been pro- 
 posed : — Heat to 21 2° F. 100 parts of methylaniline, 80 of 
 potassium chlorate, and 20 of iodine ; the reaction is 
 sluggish, and takes several days before it is complete. 
 Heat 100 parts of methylaniline, 100 of potassium chlorate, 
 and 150 of mercuric chloride. A similar result is obtained 
 by substituting 300 parts of mercuric iodide for the 150 of 
 chloride in the last recipe. 
 
 A new source of methylaniline and ethylaniline has been 
 discovered by Spiller* in the 'Hofmann gum,' a dark- 
 coloured resinous substance produced in considerable 
 quantity in the manufacture of Hofmann violet. This 
 gum, when dried and submitted to destructive distillation, 
 yields nearly pure methylaniline or ethylaniline, according 
 as the 'gum' has been derived from methylic or ethylic 
 iodide. The methylaniline from this source boils at 
 392 R, and does not yield crystalline compounds with 
 acids. With arsenic acid it furnishes a reddish-violet dye, 
 which may be converted into others of bluer shades by 
 treatment with methyl iodide, as in the Hofmann process. 
 The ethylaniline boils at about 405 ° F. Neither of these 
 bases yields Girard's blue when heated with rosaniline. 
 
 A violet, called by the fanciful name of 'Dorothea 
 violet,' and closely resembling a Hofmann violet, is pro- 
 duced by heating to 21 2° F., for two or three hours, a mixture 
 of 100 parts of alcohol, 70 of rosaniline, and 14 of ethyl 
 
 *Proc. Roy. Soc, xxi., 204. 
 
BENZYLIC VIOLETS. 399 
 
 nitrate. In this reaction ethyl nitrate is substituted for the 
 more expensive ethyl iodide employed in the Hofmann 
 process. 
 
 Various benzylic violet colours have been obtained by 
 the action of benzyl chloride not only on rosaniline but 
 also on the reddest shades of Hofmann and Paris violets, 
 the tendency of the benzylation being to give the colour a 
 bluer shade. 
 
 The benzyl chloride or ft-chlorotoluene C 6 H 5 .CH 2 C1, re- 
 quired for this purpose, is prepared by the action of 
 chlorine on boiling toluene, the hydrocarbon being distilled 
 in a current of the gas. The condensed product is then 
 rectified, and all that passes over below 338° F submitted 
 to a fresh chlorination. In this manner an oil is obtained, 
 which, when carefully fractioned between 345 and 350 R, 
 yields benzylic chloride equal to about 90 per cent, of the 
 toluene originally employed. 
 
 Violet colouring matters have also been prepared from 
 certain of the mixed tertiary monamines, such as methyl- 
 diphenylamine, benzyldiphenylamine, benzylphenyltolyl- 
 amine, and benzylditolylamine. A very fine violet blue 
 is obtained from ethyldiphenylamine by heating at 120 F. 
 to 160 F., for four or five days, a mixture of 15 lbs. of the 
 hydrochloride of the base, 5 lbs. of sulphate of copper, 1 
 of chlorate of potassium, 100 lbs. of pure siliceous sand, 
 and 10 of the hydrochloride obtained by saturating oil of 
 turpentine with hydrochloric acid. The mixture is placed 
 in flat copper dishes in a stove, and frequently agitated. 
 There should be a free circulation of air, which must be 
 kept charged with moisture by means of a jet of steam. 
 When the reaction is complete, the mass is washed with 
 water to remove soluble salts, and the colouring matter 
 extracted from the residue by means of alcohol or strong 
 hydrochloric acid. In the former case, the alcohol is 
 recovered by distillation ; in the latter, the colouring 
 
400 DYEING AND CALICO PRINTING. 
 
 matter is precipitated by water saturated with common 
 salt. It is purified by treatment with a caustic alkali, and 
 after well washing with water, taking it up with acetic or 
 hydrochloric acid. 
 
 Mr. Wanklyn also proposed to treat rosaniline with 
 isopropyl iodide obtained by the action of phosphorus and 
 iodine on glycerin. The violet colour obtained was 
 purified by a treatment similar to that employed for 
 Hofmann violet, but its use was always restricted. 
 
 A very fine violet known as 'Britannia violet* is obtained 
 by a process devised by Mr. Perkin. He heats 6 parts of 
 magenta, dissolved in 30 of methylated spirit, to 300 F., 
 for eight hours with 4 parts of brominated oil of turpen- 
 tine, a thick oily substance of the composition C 10 H 15 Br 3 
 produced by the action of bromine on oil of turpentine in 
 the presence of a large quantity of water. It possesses 
 the golden-green iridescence common to the aniline colours, 
 and can be manufactured of any shade from purple to a 
 blue-violet. 
 
 An aldehyde violet was discovered in i860 by Lauth, 
 who prepared it by treating an alcoholic solution of 
 magenta with a mineral acid, and then adding aldehyde. 
 Various shades of violet, passing ultimately into blue, are 
 produced according to the time the action is allowed to 
 proceed. It is stopped at the proper point by neutralizing 
 the acid with caustic soda, and, if necessary, precipitating 
 with common salt. The dye is readily soluble in water, 
 and dyes beautiful shades, but they are wanting in solidity. 
 
 The aniline purples are tested in the same manner as 
 magenta; but it occasionally happens that the colour is 
 not homogeneous, one portion being soluble in water, and 
 another in alcohol. In dyeing, the same general principles 
 are observed as when magenta is employed. Hofmann, 
 Paris, and Britannia violets are soluble in water, but most 
 of the others require to be dissolved in spirit, or what s 
 
D YEING WITH ANILINE VIOLETS. 
 
 401 
 
 better, a mixture of alcohol and glycerin. For woollen 
 goods with Hofmann or Paris violets they should be 
 entered at 120 R, and the temperature very gradually 
 raised to 21 2° F. The same processes are followed for 
 cotton and mixed goods as with magenta. 
 
 I 
 
 HOFMANN VIOLET ON COTTON. 
 
 The following is Messrs. Lloyd Dale's process for fixing 
 aniline colours on cotton : — 500 or 600 grammes of pure 
 tannin are dissolved in 9 litres of gum water, and an 
 amount of aniline colour added sufficient to give the de- 
 sired shade. After printing and steaming, the pieces are 
 entered at 135 to 180 F. in a bath of tartar emetic, con- 
 taining 13^ grammes of the salt per litre, then washed and 
 dried. The pattern may also be printed on with a thick- 
 ened solution of tannin, the strength of which varies with 
 the shade required (20 grammes of tannin per litre for pale, 
 and 130 for full shades), steamed, and passed through the 
 bath of tartar emetic. They are then well washed and 
 dyed in the bath of aniline colour, gradually raising the 
 temperature to boiling, at which it is maintained for about 
 twenty minutes. The pieces are finally washed and slightly 
 soaped. 
 BB 
 
402- DYEING AND CALICO PRINTING. 
 
 Aniline Blues. — A great variety of processes have 
 been proposed for the preparation of aniline blues, but at 
 the present time only a few of these are in actual use. 
 
 The 'Bleu de Paris', obtained by Messrs. Persoz, De 
 Luynes, and Salvetat in 1861, is prepared by heating a 
 mixture of 9 parts of stannic chloride and 16 of aniline to 
 a temperature of 360 R, for thirty hours in a closed vessel. 
 The black viscous mass is extracted with boiling water, 
 and the colouring matter precipitated with common salt. 
 Several re-solutions in water, and reprecipitations with salt 
 are necessary to purify it. It may be obtained in the 
 crystalline state by deposition from boiling alcohol. It is 
 precipitated from its aqueous solution by acids, by alkalis, 
 and by salts. Unfortunately the bleu de Paris is difficult 
 to prepare in large quantities. Another blue, which is 
 probably identical with this, is obtained by the pro- 
 cess Delvaux. It merely consists in heating aniline 
 hydrochloride, in closed vessels, to a temperature of 460 F. 
 
 The preparation of Bleu de MulJwuse, as carried out by 
 Messrs. Gros Renaud and G. Schaeffer, is as follows : 250 
 grammes of rosaniline nitrate, 100 of white lac, and 36 
 of sodium carbonate are boiled for an hour, with 1 litre of 
 alcohol and 3 of water. 
 
 M. Manias, of the firm Guinon, Manias, and Bonnet, 
 Lyons, devised a process by which aniline is oxidised to a 
 blue colour by means of peonine. The preparation of 
 'azuline,' as this blue is called, will be described when treat- 
 ing of the colours obtained from phenol. 
 
 Bleu de Lyon. — This colour, which is formed when ma- 
 genta is heated with excess of aniline, was patented in 
 January, i86i,by Messrs. Girard and De Laire. Although 
 it is very largely manufactured, there are considerable 
 difficulties in its preparation : in this it differs remarkably 
 from magenta, which can be made in any quantity and of 
 constant composition, for it requires not only properly 
 
MANUFA CTURE OF BLE U DE L YON. 403 
 
 selected materials, but also skill and constant care on the 
 part of the operator. 
 
 The aniline employed should be as pure and as free 
 from toluidine as possible ; that which distils over 
 in the manufacture of magenta answering admirably for 
 this purpose. The nature of the acid with which the ros- 
 aniline is in combination is also important, the best results 
 being obtained with acetic, benzoic, valeric, and oleic acids. 
 Practically it is not necessary to prepare these salts; a mix- 
 ture of rosaniline hydrochloride and sodium acetate or 
 benzoate being employed, which gives by double decom- 
 position sodium chloride and rosaniline acetate or 
 benzoate. 
 
 The operation is conducted in cast-iron pots capable of 
 holding 3 to 5 gallons each, and furnished with a stirrer, 
 the rod of which passes through a stuffing box in the lid. 
 There are also two other openings in the lid ; one closed by 
 a wooden plug, through which a small sample of the con- 
 tents may be withdrawn from time to time, to enable the 
 workman to judge of the progress of the operation; the 
 other is connected with a bent tube to condense any aniline 
 that may pass over. These pots are heated to a uniform 
 temperature of 360 F. by means of an oil bath: six pots 
 being usually arranged in the same bath. In preparing 
 the blue, a mixture of 30 lbs. of aniline and 10 lbs. of ros- 
 aniline acetate (or a corresponding quantity of a mixture 
 of magenta, with dry sodium acetate or benzoate), is intro- 
 duced into the pots, which are then heated in the oil bath. 
 At first the red colour of the mixture changes slowly, but 
 afterwards with rapidity: as soon as a sample taken out 
 with a rod gives a pure blue colour when placed on a 
 porcelain plate and moistened with a mixture of alcohol 
 and acetic acid, the reaction may be considered as com- 
 plete; to ascertain this point with precision, considerable 
 experience is necessary. In a well managed operation the 
 
4 04 DYEING AND CALICO PRINTING. 
 
 blue should remain dissolved in the aniline, the whole 
 forming a liquid of about the consistence of treacle. 
 
 In order to separate the large excess of aniline, the crude 
 product may be washed with dilute acid, or the aniline 
 may be mechanically removed by distilling it off in a cur- 
 rent of steam ; the former process is preferable, as it removes 
 most of the red and purple impurities. This yields a cheap 
 blue, fit for certain classes of dyeing ; but in order to 
 obtain pure tones, it is necessary to submit it to further 
 processes of purification. 
 
 A much purer quality may be obtained by mixing the 
 crude product with alcohol, and then pouring it into 
 water acidulated with sulphuric or hydrochloric acid. The 
 precipitate is collected and well washed with boiling, very 
 dilute acid. 'Night Blue,' or 'Bleu Lumicre,' is merely a 
 pure salt of triphenylrosaniline, C 20 H 1I ;(C 6 H 5 ) 3 N 3 , which 
 keeps its colour when seen by artificial light. It is pre- 
 pared from the refined blue by washing it with cold alcohol, 
 dissolving it in boiling alcohol, and then precipitating the 
 free base by means of caustic soda. The base is collected, 
 washed with boiling water, and then combined with the 
 quantity of acid necessary to form a salt. The great 
 inconvenience of this process is that it requires large 
 quantities of alcohol. Several other processes have been 
 proposed for the same purpose, the most recent consisting 
 in the employment of aniline or a mixture of aniline and 
 alcohol as a solvent. 
 
 By slightly varying the proportions of the materials and 
 the circumstances of the experiment, blue of various shades 
 can be obtained : of these there are four recognised in 
 commerce, as B., B.B., B.B.B., and B.B.B.B. respectively. 
 
 The shade B. is made by heating to 355 F. a mixture 
 of 2 kilos of pure rosaniline, 3 of pure aniline, and 270 of 
 benzoic acid or glacial acetic acid. When the reaction is 
 complete, the product is poured with constant agitation into 
 
BARD TS PRO CESS. 405 
 
 10 kilos of concentrated hydrochloric acid; the precipitate 
 is collected, and washed by repeatedly boiling it with a 
 large quantity of water. The precipitate, when collected, 
 pressed, and dried, weighs 3^ kilos. 
 
 For the shade B.B. 5 kilos of aniline are used instead of 
 3, and when the reaction is complete the product is mixed 
 with 7 or 8 kilos of alcohol and boiled. As soon as it is 
 cool, the colour is precipitated by 10 kilos of concentrated 
 hydrochloric acid, and then treated as for B. The yield is 
 about 1 300 grammes. 
 
 The shades B.B.B. and B.B.B.B. are obtained by purify- 
 ing B.B. by dissolving it in alcohol, or a mixture of alcohol 
 and aniline, adding alcoholic soda, filtering, and precipi- 
 tating with hydrochloric acid. 
 
 The following process for preparing aniline blue and 
 violet by the same operation is given by M. Bardy. 
 Magenta is mixed with 30 per cent, of its weight of sodium 
 acetate, and the whole evaporated to dryness; free aniline 
 and crystallised potassium acetate are then added, equal to 
 10 per cent, of the rosaniline hydrochloride, and the mix- 
 ture heated to 347 F. for several hours, until it acquires a 
 pure blue colour. The product is then boiled for some 
 time with one and a half times its weight of strong hydro- 
 chloric acid, which dissolves the purple colouring matters, 
 whilst the insoluble blue floats on the surface, and may be 
 removed. The blue is purified by washing it with water, 
 and then boiling it with 5 times its weight of caustic soda 
 solution at 32 B. for twenty minutes, diluting with 15 
 parts of boiling water, and filtering. The base is then 
 freed from traces of the purple by washing with hot alcohol, 
 and finally converted into sulphate by boiling it with its 
 own weight of sulphuric acid, diluted with 10 parts of 
 water. When the excess of acid has been removed by 
 washing, it is fit for use. To extract the purple dyes from 
 the concentrated hydrochloric acid solution, it is first dilu- 
 
4 o6 DYEING AND CALICO PRINTING. 
 
 ted with water in the proportion of 9 parts for every 8 
 of the crude blue, this throws down diphenylrosaniline 
 hydrochloride, a violet of a very blue shade, and on diluting 
 the filtrate from this, with more water (about 180 parts) 
 the monophenylrosaniline violet is precipitated. 
 
 The Bleu de Paris, previously described, has often been 
 stated to be identical or nearly identical with the Bleu de 
 Lyon or triphenylrosaniline. They are, however, widely 
 different in their nature, the former being easily soluble in 
 water and readily crystallising in sharply defined deep blue 
 needles with a coppery reflection, whilst the latter cannot 
 be obtained in distinct crystals, and it is insoluble in water. 
 This circumstance forms a great drawback in its use, as 
 when the alcoholic solution employed for dyeing is poured 
 into the bath, the colour is precipitated in a finely divided 
 state, and much of it only adheres mechanically to the 
 goods, so that it afterwards rubs off. It may be kept in 
 solution by the use of large quantities of alcohol, but this 
 adds greatly to the cost of dyeing. 
 
 Mr. Nicholson, in 1862, discovered a process by which 
 these blues might be rendered perfectly soluble in water ; 
 this consists in forming conjugate sulpho-acids with them, 
 similar to the soluble compounds obtained by treating 
 indigo with sulphuric acid. Of these acids four are known 
 to exist, and have been carefully examined.* They differ 
 from triphenylrosaniline in having one, two, three, or four 
 atoms of the hydrogen in the phenyl replaced by the 
 group HS0 3 ; the stronger the acid and the higher the 
 temperature the greater the number of hydrogen atoms 
 replaced. In the early attempts to prepare these soluble 
 blues the higher sulphonic acids only were obtained, which 
 had the disadvantage of giving shades which were less fast 
 under the influence of light, soap, and alkali than the 
 Bleu de Lyon itself. At present, however, a sodium salt of 
 
 *Bulk : Deut. Chem. Ges. Ber., v., 417. 
 
NICHOLSON'S BLUE. 407 
 
 triphenylrosaniline-monosulphonic acid, C 20 H 16 (C 6 H s ) a 
 (C 6 H 4 .S0 3 Na)N 3 , can be obtained, known as 'Nicholson's 
 Blue,' which is fast, and well adapted for the use of the dyer. 
 
 Formerly a very large excess of sulphuric acid was em- 
 ployed in the manufacture, the proportion being 20 lbs. of 
 aniline blue, and 80 of sulphuric acid, which were mixed 
 and heated to a temperature of 270° R, until the mass had 
 become homogeneous, and a sample, taken out for that 
 purpose, dissolved completely in water when excess of 
 ammonia was added. It was then poured into about 8 
 times its weight of water, and the precipitated blue, which 
 is insoluble in the strongly acid liquid, collected and 
 washed until the colour began to dissolve and pass through 
 the filter. It was then pressed, and heated with a slight 
 excess of ammonia in an enamelled cast-iron vessel until 
 the coloured salt floated on the surface as a bronzy layer. 
 It only required to be dried and ground, in order to be in 
 a fit state for the market. 
 
 In the methods more recently adopted, a sulpho acid is 
 produced which is insoluble in water; this is converted by 
 treatment with an alkali into a salt soluble in water, which 
 is then used in dyeing. The blue known as 'Nicholson's 
 Blue' is a compound of this kind, being as before stated, 
 nearly pure sodium triphenylrosaniline-monosulphonate. 
 To prepare the monosulphonic acid: 1 kilo of refined blue 
 is added, in small portions at a time, to 3 litres of sulphuric 
 acid of density 176, and the mixture heated on the water 
 bath until a sample poured into water gives a deep blue 
 precipitate, which, after being washed until no longer acid, 
 should not colour the water, but must be completely solu- 
 ble in ammonia: this usually takes about five or six hours. 
 The product is then poured into 30 litres of water with 
 constant agitation, collected on woollen filters, and 
 thoroughly washed. The pure acid thus obtained, is con- 
 verted into the sodium salt by digesting it with a quantity 
 
4o8 DYEING AND CALICO PRINTING. 
 
 of soda-ley, not quite sufficient for saturation, filtering the 
 solution, and evaporating in enamelled basins in a heated 
 chamber. It then forms a grey-black amorphous mass, 
 which dissolves easily in hot water. As met with in com- 
 merce it is frequently mixed with an excess of carbonate 
 of soda. 
 
 ANILINE BLUE ON WOOL. 
 
 A toluidine blue, very similar to the triphenylrosaniline 
 salt known as the ' Bleu de Lyon,' may be obtained by 
 heating rosaniline acetate with twice its weight of toluidine. 
 Abundance of ammonia is evolved, and a brown mass with 
 metallic lustre is obtained, which is soluble in alcohol 
 with a deep indigo-blue colour. This dye is the acetate of 
 tritolylrosaniline, a base which may be regarded as rosani- 
 line C 20 H 19 N 3 in which three of the hydrogen are replaced 
 by tolyl, and having the formula C 20 H 16 (C 7 H 7 ) 3 N 3 . 
 
 Diphenylamine blue. — Hofmann was the first to notice 
 that a blue colour was produced by the action of various 
 reagents on diphenylamine ; the discovery of a diphenyla- 
 mine blue fit for use in dyeing is due, however, to Messrs. 
 Girard and De Laire. It is prepared in a manner similar 
 to magenta, by the action of oxidising agents on a mixture 
 
DIPHENYLAMINE BLUE. 409 
 
 of diphenylamine and ditolylamine, and is in all proba- 
 bility identical with the Bleu de Lyon. Its formation 
 would then be represented by the equation : — 
 
 2C 12 H 12 N + C u H lfl N - H 9 = Q H 1G (C 6 H 5 ) 3 N 3 
 Diphenylamine. Ditolylamine. Triphenylrosaniline. 
 
 When three equivalents of aniline are heated to about 
 460 or 470 F. with two of aniline hydrochloride in a 
 flask furnished with a condensing tube, a reaction takes 
 place, accompanied by disengagement of ammonia and 
 formation of diphenylamine. The operation, however, is 
 very tedious, only about one-eighth of the aniline being 
 converted after 30 hours' digestion. In order to extract 
 the diphenylamine, the product is dissolved in hydrochloric 
 acid and diluted with a large quantity of hot water; this 
 decomposes the diphenylamine hydrochloride, and the 
 liberated base floats on the surface in the melted state. It 
 may be purified by recrystallisation from ether or benzene. 
 
 In order to prepare the commercial diphenylamine, 
 which, as has previously been stated, is a mixture of 
 diphenylamine and ditolylamine, a suitable aniline is 
 chosen and a portion converted into hydrochloride; 740 lbs. 
 of this hydrochloride and 100 of the aniline are introduced 
 into an enamelled cast-iron vessel, closed by a lid and 
 furnished with a safety valve, a manometer, a screw valve 
 opening into a tube connected with a worm, and a tube 
 closed at the lower end and long enough to dip into the 
 mixture in the boiler; this tube is partly filled with mercury, 
 into which is plunged the bulb of a thermometer. The 
 mixture is gradually heated, and kept for about two hours 
 at a temperature of 420° to 428° F. ; the screw valve is 
 now closed, and the temperature gradually raised to about 
 480 F., during which the pressure in the interior increases 
 to about 5 atmospheres. The time required for an opera- 
 tion is 12 hours, during the last 6 of which the temperature 
 should be 465 ° — 500 F. When cold, the product is 
 
4 io DYEING AND CALICO PRINTING. 
 
 removed from the boiler, dissolved in 140 lbs. of hydro- 
 chloric acid by the aid of a gentle heat, and poured into 
 60 or 80 gallons of water; this precipitates the dipheny- 
 lamine, whilst the unaltered aniline remains in solution as 
 hydrochloride. The diphenylamine, after being washed 
 first with water and then with a dilute alkaline solution, is 
 purified by distillation, or by crystallisation from coal oil or 
 petroleum. 
 
 Although almost all the oxidising agents which have 
 been proposed for the preparation of magenta may 
 be employed to transform diphenylamine into the blue 
 colouring matter, trichloride of carbon C 2 C1 C , is that 
 which has been found to give the best results. The 
 operation is conducted in enamelled iron retorts of 
 the capacity of about 10 gallons, furnished with agitators, 
 and heated in an oil bath. A mixture of 24 lbs. of 
 carbon trichloride, and 20 lbs. of the diphenylamine 
 are introduced into each of these, and the temperature 
 gradually raised to 355° F. which should not be exceeded, 
 as otherwise a portion of the blue is apt to be destroyed. 
 During the reaction carbon dichloride (perchlorethylene), 
 CXI i} distils, the quantity of which corresponds very 
 nearly to that of the trichloride originally employed. 
 When the operation is finished, which usually occupies three 
 or four hours, and the product is cold, it is dissolved in 
 twice its weight of aniline heated to 212° F. This solution 
 is then poured very slowly into ten times its weight of coal 
 oil with constant agitation ; the blue is precipitated by this 
 means as an impalpable powder, which is collected, washed 
 with coal oil, and again dissolved and reprecipitated in a 
 similar manner. Finally, it is redissolved in twice its 
 weight of aniline, precipitated by 4 parts of hydrochloric 
 acid, collected, and washed with boiling water. The crude 
 blue may also be purified by boiling it with soda solution, 
 extracting the resinous matters from the pulverised base 
 
AZODIPHENYL BLUE. 411 
 
 by hot petroleum, dissolving the residue in alcohol, and 
 precipitating by hydrochloric acid. 
 
 Another process, devised by Brimmeyr, consists in heat- 
 ing the diphenylamine to about 245° F. for four or five 
 hours, with an equal weight of oxalic acid ; the amount of 
 colouring matter produced is but small, however. 
 
 This blue, which is insoluble in water, gives very pure 
 shades in dyeing. 
 
 Azodiphenyl blue. — This blue is prepared by heating 1 
 part of azodiphenyldiamine (diazoamidobenzene, p. 429), 1 
 part of aniline, and 2 of alcohol to 320 F. for four or five 
 hours. The dark blue product is then washed with boiling 
 water, dissolved in a mixture of alcohol and hydrochloric 
 acid, and the base thrown down with caustic soda. By dis- 
 solving the well washed base in a mixture of hot alcohol and 
 hydrochloric acid, and concentrating the solution if neces- 
 sary, a dark blue crystalline hydrochloride is obtained, 
 which is insoluble in water, but readily soluble in alcohol, 
 especially if it is warm. The composition of the hydro- 
 chloride is C 18 H 15 N 3 .HC1 the base being formed in the 
 manner represented in the following equation : — 
 
 C ia H u N 2 + C 6 H 7 N = C 1S H 15 N 3 + NH 3 
 Diazoamido- Aniline. Azodiphenyl 
 
 benzene. blue. 
 
 This blue has the same composition as violaniline, but 
 nothing is known at present of the relation between the 
 two substances. 
 
 This colour dyes wool and silk of a deep violet-blue. 
 
 A variety of processes are employed in dyeing with 
 aniline blues. Those which are insoluble in water, are dis- 
 solved in alcohol and wood spirit, or a mixture of these 
 with glycerin ; the purer the blue, the more solvent does it 
 require. Like most of the aniline colours, they dye wool 
 and silk without mordants; a hot bath acidulated with sul- 
 phuric acid, being used for the former, and one of a lower 
 temperature, acidulated with tartaric acid, for the latter. 
 
4 I2 DYEING AND CALICO PRINTING. 
 
 The soluble sodium salt of the monosulphonic acid of 
 triphenylrosaniline (Nicholson Blue), only gives feebly 
 coloured solutions, but the colour comes out with great in- 
 tensity when a mineral acid is added to them. Woollen 
 piece goods are usually entered into the bath rendered 
 alkaline with soda, water glass (an alkaline silicate), or 
 borax, at 120° F., and the temperature gradually raised to 
 near the boiling point, at which it is kept for about half an 
 hour. The wool extracts the salts in the colourless state, 
 and has such an affinity for them that they cannot be 
 removed by washing with water: on dipping them in an 
 acid, however, the base is removed, and the coloured acid 
 remains combined with the fibre. In order to watch the 
 progress of the dyeing, several strips of the same stuff are 
 attached to the pieces, one of which is removed from time 
 to time, washed, and dipped in acidulated water to bring out 
 the colour. When the required shade has been attained the 
 pieces are taken out, winced in cold water, and then passed 
 through a bath of dilute sulphuric acid to develope the 
 colour: they are finally thoroughly washed in cold water. 
 
 A blue of this class, manufactured by Messrs. Brooke, 
 Simpson, and Spiller, is a very permanent colour, and is 
 sometimes used with camwood to produce a cheap imita- 
 tion of an indigo vat blue. 
 
 The soluble blue consisting of the higher sulpho-acids, 
 which now comes but little into the market, dyes silk 
 and wool with moderate facility if the bath is acid, but 
 not if it is neutral or alkaline. 
 
 The aniline blues have no affinity for cotton fibre, and 
 the attempts to dye them with various mordants have not 
 been very successful. Cotton skeins may, however, be 
 died blue by working them first in a solution of alum and 
 then in soap : the fibre thus mordanted takes up the blue 
 readily, but although it resists light fairly, it cannot be 
 washed with soap. 
 
PRINTING ANILINE BLUE. 
 
 413 
 
 Nicholson's blue on cotton. 
 
 In printing, the same processes with albumen and lac- 
 tarin may be employed for the blue, as those previously 
 described for magenta. Perkin's arsenious acid process, 
 slightly modified, can also be used. The thickened aniline 
 colour is mixed, according to its strength, with one-eighth to 
 one-fourth of its bulk of a saturated solution of arsenious acid 
 in glycerin, and an equivalent quantity of acetate of alu- 
 mina. The mixture is then printed and steamed for forty- 
 five minutes, after which it is worked in boiling soap-lye 
 for half an hour to brighten the colour. 
 
CHAPTER XIV. 
 
 ANILINE GREEN. — ANILINE YELLOW. 
 
 Aniline Greens. — One of the first of these colours 
 obtained from aniline was a deep green, called 'emeraldine,' 
 for which Messrs. Calvert, Gift, and Lowe took out a 
 patent in i860. The fabric was first prepared bypassing 
 it through a bath containing one part of potassium chlorate 
 in 200 of water; it was then dried, and printed with an 
 acid aniline hydrochloride. After ageing for a few hours 
 the colour is developed, and the goods only require to be 
 well washed. When passed through a solution of potassium 
 bichromate, the colour is changed to a deep indigo-blue, 
 which was called 'azurine.' Both these colours are dull. 
 
 Aldehyde green, a very beautiful colour, was accidentally 
 discovered in a remarkable manner. In 1861 Lauth had 
 succeeded in obtaining a blue dye by the action of alde- 
 hyde on an acid solution of aniline; there was, however, 
 great difficulty in fixing it. Shortly afterwards Cherpin, 
 the chemist to the dyeworks of M. Usebe, near St. Ouen, 
 tried several experiments with the colour, during which he 
 mentioned to a photographic friend the difficulty there was 
 in fixing the colour; this gentleman naturally suggested 
 hyposulphite of sodium, with which he was in the habit of 
 'fixing' his photographs. On making the apparently 
 useless experiment, M. Cherpin found that the blue was 
 converted into a splendid green dye, now known as 
 'aldehyde green.' 
 
 In 1862 a patent was taken out for the production of 
 this colour in the following manner: — 2 lbs. of rosaniline 
 
ALDEHYDE GREEN. 
 
 415 
 
 are dissolved in 4 lbs. of sulphuric acid of density v6^ which 
 has previously been diluted with 1 lb. of water. When 
 complete solution has been effected, 8 lbs. of a strong 
 alcoholic solution of aldehyde is added in small portions 
 at a time, and the mixture gently heated until a drop of 
 it, when allowed to fall into water, gives a fine blue 
 coloration without any shade of red. As soon as the 
 reaction is complete, which ordinarily takes place in about 
 20 minutes, the product is poured into a boiling solution of 
 8 lbs. of sodium hyposulphite in 5 gallons of water. The 
 mixture is then boiled for 7 or 8 minutes, and the beautiful 
 green-coloured solution separated by filtration from the 
 bluish-grey insoluble precipitate. 
 
 The green solution may be precipitated by acetate of 
 sodium, tannin, or oxide of zinc, and the green paste dried, 
 or employed for dyeing in the moist state. This green is 
 employed chiefly in silk dyeing, and gives splendid shades, 
 which are very brilliant, both by artificial light and by 
 daylight; as, however, it cannot be kept any length of 
 time without deterioration, dyers usually prepare it for 
 themselves as they require it. 
 
 
 
 
 
 
 
 
 
 
 
 
 ALDEHYDE GREEN ON COTTON. 
 
41 6 DYEING AND CALICO PRINTING. 
 
 The composition and chemical natute of this substance 
 have not as yet been accurately determined; it is un- 
 doubtedly the salt of an organic base, to which Hofmann 
 assigns the formula C 2 oH 27 N 3 SoO and which may be 
 obtained by decomposing an aqueous or alcoholic solution 
 of aldehyde green with soda or ammonia. It is of a pale 
 green colour, and slightly soluble in alcohol. With acids 
 it forms bright green salts, which are very unstable. 
 
 According to Lauth, this green is produced whenever 
 aldehyde blue is brought in contact with nascent sulphur, 
 an hypothesis which is strongly supported not only by 
 Hofmann's analysis of the base, but also by Hirzel's method 
 of preparation, in which the aldehyde blue is treated with 
 ammonium sulphide, in place of the hyposulphite. Lucius 
 maintains, however, that aldehyde green exists ready 
 formed in the solution obtained by the action of aldehyde 
 on an acid solution of rosaniline, and that the sodium 
 hyposulphite merely removes the blue and violet-coloured 
 substances produced at the same time. 
 
 Iodine green. — By far the most important of the aniline 
 greens is that known as the ' iodine green,' which is always 
 produced in larger or smaller quantity, when an excess of 
 methyl or ethyl iodide acts on an alcoholic solution of ros- 
 aniline, Hofmann violet being first produced, which is then 
 converted, by the continued action of the iodide, into dime- 
 thy! iodide of trimethylrosaniline C 20 H 1G (CH 3 ) 3 N 3 (CH 3 I) 2 if 
 the methyl compound has been employed. An explana- 
 tion of the fact that this green colouring matter was not 
 observed until two years after the discovery of the Hof- 
 mann violet, and during which such enormous quantities 
 of the latter were manufactured, is offered by the circum- 
 stance that the most favourable conditions for the production 
 of the violet are those which are most unfavourable for the 
 formation of the green. It was only, therefore, when the 
 ordinary methods were departed from, that the green was 
 
IODINE GREEN. 417 
 
 produced in quantity sufficient to be isolated, and its pro- 
 perties ascertained. 
 
 On this account it is somewhat difficult to fix the exact 
 date of its discovery. Messrs. Tillmanns de Crefeld, 
 Meister, Lucius, Briining, Poirrier, and Chappat all seem to 
 have manufactured it in 1865. To Mr. Wanklyn, however, 
 is due the merit of first having published a process for its 
 preparation. This was contained in a patent dated the 6th 
 of November, 1865; and although itself of comparatively 
 little value from an industrial point of view, it has served 
 as the starting point for the present successful methods. 
 
 Wanklyn's process consisted in heating equal parts of 
 rosaniline, methyl iodide, and methyl alcohol for three 
 hours to 230° F.; the product, which is principally Hofmann 
 violet, is washed with a dilute solution of sodium carbonate, 
 decomposed by caustic soda, and the liberated base, after 
 being dried and pulverised, is again treated with the 
 alcoholic iodide; a third operation suffices to convert 
 nearly all the violet into green. As the latter is very 
 soluble in dilute solutions of sodium carbonate, it is easily 
 separated from the violet which has not been converted, 
 and also from the impurities produced at the same 
 time. 
 
 Important improvements have been made in this manu- 
 facture by Hofmann and Girard; for although all the 
 salts of rosaniline are capable of being converted into 
 the green, yet some give much better results than others, 
 such as the sulphate, nitrate, benzoate, and especially 
 the acetate. As the presence of water interferes consider- 
 ably with the reaction, it is advisable that all the materials 
 should be in as dry a state as possible; moreover, as the 
 iodine green begins to decompose at 230° R, care must be 
 taken that the temperature should never exceed that 
 point. 
 
 The iodine green is now manufactured in enamelled 
 CC 
 
41 8 DYEIXG AND CALICO PRINTING. 
 
 iron digestors of a capacity of about 16 or 20 gallons, 
 and capable of bearing an internal pressure of twenty to 
 twenty-five atmospheres. The lid is furnished with a 
 pressure gauge, and also with a screw tap communicating 
 with a worm, so that at any given moment the liquid pro- 
 ducts of the reaction may be allowed to pass off, and be 
 condensed. The apparatus is heated by means of a water 
 bath or a double steam jacket, care being taken that the 
 temperature never rises above 230" F. Twenty lbs. of pure 
 dry rosaniline acetate, 40 of pure methyl iodide, and 40 of 
 highly rectified methylic alcohol, boiling at 147° — 152° F. 
 are introduced into the apparatus, which is gradually 
 heated. The pressure in the interior of the digestor, as 
 indicated by the manometer, rapidly increases to eight 
 atmospheres, and then more slowly to ten or eleven, which 
 it never ought to exceed. In the course of four or five 
 hours, when the reaction is complete, the steam is shut off, 
 and the apparatus is allowed to cool. The pressure then 
 gradually falls to about four atmospheres, when the screw 
 valve is opened, and the volatile products removed by dis- 
 tillation. Besides the methylic alcohol and excess of 
 methyl iodide, there are considerable quantities of methyl 
 acetate and oxide formed, the latter of which escapes with 
 violence on opening the valve. The semi-fluid mass con- 
 taining the colouring matters is poured into a large vat, 
 heated by steam, and containing 120 gallons of hot distilled 
 water: here the green dissolves entirely, together with 
 a small portion of the violet, which is kept in solution by 
 the acid set free during the reaction ; the greater portion of 
 the violet, however, remains undissolved, and is separated 
 by filtration. To the clear filtered liquor, which must be 
 kept boiling, 70 lbs. of common salt are added, and the 
 free acid is then carefully neutralised with crystallised 
 sodium carbonate in order to precipitate the violet still in 
 solution. To ascertain the exact point when all the violet 
 
MANUFACTURE OF IODINE GREEN 419 
 
 has been thrown down, a sample is withdrawn from time 
 to time, filtered through sand, and a skein of silk immersed 
 in the hot liquid. When the silk becomes dyed a pure 
 green colour without any admixture of violet, it is a sign 
 that sufficient sodium carbonate has been added; the 
 amount usually required for this purpose being rather more 
 than 3 lbs. After the solution has become quite cold, it is 
 filtered through a sand filter to remove the finely divided 
 violet, and then precipitated with a cold saturated aqueous 
 solution containing about 6 lbs. 14 ozs. of perfectly pure 
 picric acid. In this way a picrate of the iodine green is 
 obtained, which is only very slightly soluble in water; as 
 it is in a fine state of division, it is collected, washed slightly, 
 and allowed to drain until it becomes of a pasty consistence, 
 in which form it is sent into the market. Although it 
 possesses great tinctorial powers, its solubility in water is 
 so slight that it is necessary to employ it in alcoholic 
 solution. 
 
 In a well conducted operation about 60 per cent, of the 
 colouring matter obtained is green, and about 40 violet. 
 The latter may be converted into green by further treat- 
 ment with methyl iodide in the following manner: — The 
 precipitated violet iodide, after having been carefully 
 washed and dried, is finely powdered, and dissolved in 
 alcohol, adding sufficient caustic soda in alcoholic solution 
 to combine with the hydriodic acid and liberate the base. 
 The whole is now introduced into a vessel furnished with 
 an agitator and a return condenser, and the requisite quan- 
 tity of methyl iodide added. The liquid is carefully heated 
 by means of a water bath, to the temperature of 120 F., and 
 as the production of the green is very rapid, care must be 
 taken to stop the action as soon as the transformation is 
 complete, by cooling rapidly, adding acetic acid, and pour- 
 ing into a large quantity of hot water. After the removal 
 of the unattacked violet by means of common salt and 
 
4 20 DYEING AND CALICO PRINTING. 
 
 carbonate of soda, the green may be precipitated by picric 
 acid as before. This green is generally purer than that 
 made directly from rosaniline, and gives finer shades in 
 dyeing. 
 
 WOOL DYED WITH IODINE GREEN. 
 
 Soluble green. — The inconvenience arising from the in- 
 solubility of the picrate in water has led to the substitution 
 of a salt of zinc, such as the acetate, chloride, or sulphate, 
 for picric acid in the precipitation of the green from its 
 aqueous solutions containing common salt. The precipi- 
 tates, which are soluble in water, are double salts of zinc 
 and iodine green, and may be prepared either from the 
 product obtained directly from rosaniline, or that from 
 Hofmann violet; in the latter case the colour is purer. 
 The shade which the zinc compound gives in dyeing is less 
 yellow than that of the picrate. 
 
 Crystallised green. — The iodine green may be obtained 
 in a crystalline state from a concentrated solution. For 
 this purpose, the crude product from 20 lbs. of rosaniline is 
 poured into 24 gallons of boiling water, and after separa- 
 ting the precipitated violet and adding 14 lbs. of common 
 salt, the violet in solution is completely removed by adding 
 a slight excess of sodium carbonate, even at the risk of 
 
CRYSTALLISED IODINE GREEN. 421 
 
 destroying a small quantity of the green, which is easily 
 altered by ebullition with the alkaline salt. The solution, 
 which should be filtered boiling hot into vats containing 
 copper rods, deposits the dye in beautiful green needles 
 with a metallic-bronze lustre. The finest are formed on 
 the rods and sides of the vessel, whilst at the bottom there 
 is a crystalline crust, which is less pure. It is fit for use 
 after being washed once or twice with a small quantity of 
 cold water to remove the adhering sodium chloride. In 
 order to obtain it chemically pure, however, the purest 
 green crystals should be dissolved in boiling absolute 
 alcohol, the solution filtered, and then mixed with an 
 excess of anhydrous ether; the crystalline precipitate thus 
 produced, when again dissolved in boiling alcohol and 
 allowed to cool slowly, deposits the pure salt in magni- 
 ficent green prisms having a lustre equal to that of the 
 elytra or wing cases of cantharides. 
 
 Iodine green, or Dimethyliodide of trimethylrosaniline, 
 which in the crystalline state has the formula C 20 H 16 (CH 3 ) 3 
 N 3 (CH 3 I) 2 + OH, is soluble in alcohol and in water, but 
 insoluble in ether and in benzene. The corresponding 
 acetate crystallises in slender needles, and the nitrate in 
 prisms. Concentrated mineral acids, reducing agents, and 
 oxidising agents, all destroy the green. When treated with 
 alkalis, the iodine green is converted into the corresponding 
 base, which is colourless : it may also be obtained from the 
 picrate by decomposing its solution in ammoniacal alcohol 
 with caustic soda. 
 
 Transformation of iodine green.— -The crystals of iodine 
 green become changed when left for some time in a 
 vacuum, or when exposed to light; they will now be found 
 to be only partly soluble when treated with water, yielding 
 a green solution, and leaving a residue of a beautiful violet 
 colour, which is extremely soluble in alcohol. This de- 
 composition takes place in the course of a few hours at 
 
422 DYEING AND CALICO PRINTING. 
 
 212° F., and instantly at 300° R; thus the green dissolves in 
 boiling aniline with a splendid violet colour. In this case 
 the green loses a molecule of methyliodide and a molecule 
 of water, and becomes transformed into monomethyliodide 
 of trimethylrosaniline in the following manner: — 
 
 Q H 10 (CH 3 ) 3 N 3 (CH 3 I) 2 .OH 2 - C 20 H 16 (CH 3 ) 3 N 3 .CH 3 I + 
 
 Dimethyliodide of trimethyl- Monomethyliodide of 
 
 rosaniline trimethylrosaniline 
 
 CH3I + OH, 
 
 If a solution of iodine green in methyl alcohol be heated 
 to 212 F. for two or three hours in sealed tubes, it 
 splits up into monomethyliodide and trimethyliodide of 
 trimethylrosaniline, the latter of which, being compara- 
 tively insoluble, separates as the liquid cools in long 
 cantharides-green needles. It may also be obtained by 
 the direct union of methyl iodide with aniline green. It is 
 but very slightly soluble in boiling alcohol, giving a violet- 
 blue solution. 
 
 Perhin's green. — There is also another green dye, a 
 derivative of magenta, known in commerce by the above 
 name. The method employed in its preparation has not 
 been made public, but although it resembles the iodine 
 green more closely than the aldehyde green, it differs from 
 it in its solubility, and in being precipitated from its solu- 
 tions by the alkaline carbonates such as sodium carbonate. 
 It is also precipitated by picric acid, forming a picrate 
 closely resembling that from iodine green, and which 
 crystallises from alcohol in small prisms having a golden 
 iridescence. This colour is now extensively employed, 
 chiefly for calico printing. 
 
 Methyl green. — Dyes very similar to those prepared by 
 the action of methyl iodide on magenta, may be obtained 
 directly from methylaniline, or rather a mixture of methyl- 
 aniline and methyltoluidine. When such a mixture is 
 oxidised, it yields the so-called 'methyl violet,' or Paris 
 
METHYL GREEN. 
 
 423 
 
 violet (p. 397), which appears to differ from Hofmann 
 violet in retaining its colour when seen by artificial light. 
 If this be methylated by treatment with methyl chloride, or 
 methyl nitrate, 'methyl green' is produced. It may be 
 separated from the unaltered violet by mixing the solution 
 with chloride of zinc, and then gradually adding carbonate 
 of soda. When the violet lake which is at first thrown 
 down ceases to appear on the further addition of carbonate 
 of soda, the solution is concentrated by evaporation, and 
 on cooling, deposits crystals of a double salt of the methyl 
 green hydrochloride, with chloride of zinc. It seems to 
 differ from the iodine green in being more soluble in water, 
 and in not being decomposed when its solution is boiled. 
 It gives very fresh colours, and wool may be dyed with it 
 without any preparation. 
 
 METHYLANILINE GREEN ON CALICO. 
 
 The violets obtained from the tertiary monamines, 
 noticed on p. 399, also yield greens when properly treated 
 with methyl iodide or nitrate. 
 
 The general principles of the methods to be used in dye- 
 ing with these greens are the same as those for the other 
 aniline colours. In order to obtain full shades on wool, 
 Dale recommends that it should be worked in a very dilute 
 
424 DYEING AND CALICO PRINTING. 
 
 solution of calcium hypochlorite (chloride of lime) before 
 dyeing: it then takes up the colour very readily. In 
 using the greens sold as insoluble tannates, they must be 
 dissolved in water acidulated with sulphuric acid ; wools 
 and silk can then be readily dyed with them, employing 
 the bath at a higher temperature for the former than for 
 the latter. 
 
 The so-called 'Pomona paste' of commerce, does not 
 require the use of alcohol, as it is readily soluble in water. 
 Wool is dyed with it in the following manner. A bath is 
 prepared having enough silicate of potash dissolved in it 
 to give the water a soapy feel. In this the wool or woollen 
 yarn is worked at a temperature of 160 F. until it is 
 thoroughly wetted. The colour, which has previously been 
 dissolved in a small quantity of cold water, is now added 
 very gradually to the bath, and the wool worked in it until 
 it has taken up the proper amount of colour. This is 
 ascertained by taking out some waste scraps which have 
 been dyed along with it, and dipping them into very dilute 
 acetic acid. As soon as the proper shade is attained, the 
 wool is taken out and put into a bath of very dilute acetic 
 acid at i6o° F., to which a little tannin, or extract of galls 
 may be added to fix the colour. If a yellow shade of 
 green is required, picric acid may be added to the bath. 
 
 To dye alpaca with aniline green, the thoroughly wetted 
 stuff is worked in a bath containing 4 ozs. of aniline green, 
 4 ozs. of strong ammonia, and 4 ozs. of silicate of soda to 
 each 10 lbs. of the material, then passed through a tannin 
 bath, and again returned to the colour bath; finally, it is 
 brightened in a somewhat strong acetic acid bath. 
 
 To dye cotton, it is first worked thoroughly in a tannin 
 bath made with sumach, galls, or myrobalans, then in 
 double muriate of tin. After this it is winced in water, 
 and the cotton, thus mordanted, worked in a cold bath of 
 the aniline green. 
 
ANILINE YELLOWS. 425 
 
 Linen may be dyed with aniline green after having been 
 mordanted with tannin and acetate of alumina. The yarn 
 is soaked for 12 hours in a tannin bath made by boiling 
 8 lbs. of sumach in water, after which it is mordanted with 
 acetate of alumina made by adding a solution of 1 lb. of 
 alum to one of 1 y 2 lbs. of acetate of lead. The yarn thus 
 prepared is worked in the bath of iodine green until it has 
 acquired the proper shade. If a yellow tint is desired, the 
 goods may be topped with picric acid. 
 
 Sevez recommends for printing, 1 litre of gum water, 
 250 grammes of paste green, and 150 grammes of bi- 
 sulphite of soda. The mixture is heated in the water bath 
 until homogeneous, and then allowed to stand for three or 
 four days, when it is ready for printing. The colour will 
 bear steaming, and yields more satisfactory results upon 
 silk and worsted than upon calico. 
 
 ANILINE Yellows. — Generally speaking, the aniline 
 yellow and orange colouring matters differ from those 
 previously described, inasmuch as they are not regularly 
 manufactured, but arise as bye products in the preparation 
 of other aniline colours. 
 
 Chrysaniline, or phospJiinc, is a bye product obtained in the 
 preparation of magenta, and which, according to Hofmann, 
 has the formula C 20 H 17 N 3 differing from that of rosaniline, 
 C 2 oH 10 N 3 , by two atoms of hydrogen. It was first ob- 
 tained by Nicholson from the magenta residues, by sub- 
 mitting them to a current of steam for some time, and 
 then precipitating the chrysaniline by adding nitric acid to 
 the solution. It is manufactured by Messrs. Brooke, 
 Simpson, and Spiller, but their process is kept secret. 
 
 There is also a yellow compound formed by the action 
 of oxidising agents on toluidine, discovered by Girard and 
 Chapoteaut in 1866, which possesses characters almost, if 
 not quite, the same as those assigned to chrysaniline. 
 From the results of the analysis, and the mode of 
 
426 DYEING AND CALICO PRINTING. 
 
 formation, the substance chrysotohtidine is found to be a 
 homologue of rosaniline, having the formula C 21 H 21 N 3 . 
 As there is but a very slight difference in the centesimal 
 composition assigned to chrysaniline and chrysotoluidine 
 respectively, it is possible that these two substances may 
 be isomeric, if not identical. In fact, whilst chryso- 
 toluidine has been prepared from crystallised toluidine, 
 chrysaniline has been obtained from the residues of 
 magenta made from commercial aniline, which is always 
 rich in the isomeric liquid toluidine. 
 
 As already noticed, chrysotoluidine occurs along with 
 violaniline and mauvaniline in the insoluble residue ob- 
 tained in the manufacture of magenta, and a process has 
 been given (p. 392) for isolating the mauvaniline. Girard 
 and De Laire treat the crude magenta, obtained from the 
 action of arsenic acid on aniline, in the following way: — 
 2000 lbs. of the raw product are dissolved in 170 lbs. of 
 hydrochloric acid diluted with 2500 gallons of boiling 
 water. The violaniline remains undissolved, and is sepa- 
 rated by filtration; 250 lbs. of hydrochloric acid are added 
 to the filtrate, which, on cooling, deposits 80 or 90 lbs. of 
 mauvaniline hydrochloride mixed with a little rosaniline 
 and resinous matters ; 1250 lbs. of common salt are added 
 to the filtrate, which precipitates 60 to 70 lbs. of a mixture 
 of mauvaniline and rosaniline salts, and after this has been 
 separated 166 lbs. of soda ash (containing 60 per cent, of 
 soda) is added. The precipitate thus obtained, which 
 weighs 410 to 420 lbs., consists almost entirely of rosani- 
 line salts, mixed, however, with a very small quantity of 
 salts of chrysotoluidine. 
 
 After this has been separated, the filtrate is completely 
 saturated by adding to it 75 lbs. more of soda ash; this 
 throws down the chrysotoluidine as an amorphous pre- 
 cipitate weighing from 75 to 80 lbs. In order to purify 
 it, 100 lbs. are boiled with 250 gallons of lime water 
 
CHR YSO TOL UID1NE. 427 
 
 containing a little lime in suspension, and after 4 or 5 
 hours' boiling it is filtered, and the filtrate rendered acid 
 with hydrochloric acid; on cooling, it deposits a well 
 crystallised salt of rosaniline, containing a little chryso- 
 toluidine, and known in commerce as yellow magenta. It 
 is probable that this colour is identical or very similar to 
 the 'cerise' obtained from magenta residues in the manner 
 described on p. 382. 
 
 In order to separate the chrysotoluidine from the insolu- 
 ble residue, it is heated in an enamelled cast-iron vessel 
 with a little water, and enough hydrochloric acid is added 
 to exactly neutralise the lime. The chrysotoluidine melts 
 and floats on the surface of the strong chloride of calcium 
 solution, from which it is removed by a skimmer, and 
 washed with a little cold water. One hundred lbs. of the 
 product are then dissolved in a boiling mixture of 200 
 gallons of water with 100 lbs. of hydrochloric acid. As 
 soon as it is completely dissolved, 10 lbs. of zinc are added, 
 and the whole boiled for eight hours; by this means the 
 last traces of rosaniline are converted into leucaniline and 
 removed. When cold, the solution is exactly neutralised 
 with carbonate of soda, and precipitated by the addition 
 of 20 lbs. of common salt. The yield is 80 lbs. of 
 amorphous chrysotoluidine. 
 
 In order to purify this, it is dissolved in 200 gallons of 
 boiling water slightly acidulated, precipitated by 50 lbs. of 
 caustic soda at 12 Baume, the precipitate washed with 
 cold water, and 8 lbs. of sulphuric acid poured over it. It 
 is then again dissolved in 200 gallons of hot water, boiled 
 for two hours, and filtered when cold. This solution is 
 then carefully precipitated with carbonate of soda, which 
 throws down about 20 lbs. of a brownish-yellow colouring 
 matter fit for dyeing skins. On adding common salt to 
 the filtrate, 25 lbs. of nearly pure chrysotoluidine are ob- 
 tained. Each of these precipitates, after being collected 
 
4 28 DYEING AND CALICO PRINTING. 
 
 and pressed, is converted into sulphate by the addition of 
 the exact amount of sulphuric acid. 
 
 Chrysotoluidine may be prepared directly from the 
 crystalline toluidine by the action of heat on the arseniate, 
 but as that salt is difficultly fusible, it is advisable to add 
 an excess of toluidine acetate. It then begins to fuse at 
 265° F., and at 300 F. decomposes, water being given off 
 and an orange-coloured matter formed. Carbon trichloride 
 or stannic chloride (bichloride of tin), may be conveniently 
 substituted for the arsenic acid. The action is then 
 perfectly regular, although a small quantity of ditolylamine 
 is always produced. 
 
 In order to purify the crude product, it is boiled with 
 excess of soda, the unaltered toluidine being driven off by 
 a current of steam. The liberated base is then washed, 
 dissolved in a slight excess of dilute hydrochloric acid, and 
 precipitated by picric acid in excess. The acid picrate of 
 chrysotoluidine thus obtained may be purified by crystal- 
 lisation, and the base set free by treatment with a solution 
 of caustic soda. Chrysotoluidine, may also readily be 
 obtained by the action of nitrate of mercury on toluidine 
 acetate. 
 
 Pure clirysotohiidiiie, C.^H^N-, is a yellow amorphous 
 powder, resembling recently precipitated lead chromate. 
 It is but slightly soluble even in boiling water, but is 
 readily soluble in alcohol, ether, and benzene. When sub- 
 mitted to dry distillation, it yields ditolylamine. It unites 
 with acids forming two series of salts, one monacid, and 
 the other diacid. These, as a rule, crystallise well, the 
 most remarkable being the nitrates. The nitrates form 
 ruby-red needles, and are very insoluble, so that if a dilute 
 solution of potassium nitrate be added to a moderately 
 concentrated solution of a chrysotoluidine salt, a crystal- 
 line precipitate of the mononitrate is immediately pro- 
 duced. The diacid salt is formed on adding concentrated 
 
CHR YSOTOL UIDINE. 429 
 
 nitric acid to a solution of the monacid salt. It is decom- 
 posed by water, losing its acid, and being converted into 
 the monacid salt. 
 
 ANILINE YELLOW. 
 
 By treating chrysotoluidine with methyl iodide, three 
 atoms of its hydrogen are replaced by methyl, giving rise 
 to the iodide of a new base, trimethylchrysotoluidine, 
 C 21 H 18 (CH 3 ) 3 N 3 , which crystallises in brilliant crimson 
 needles. They are soluble in water, and dye wool and silk 
 a brilliant orange-red. 
 
 Scheurer-Kestner obtained an orange dye by dissolving 
 mauveine in dilute hydrochloric acid, and treating it with 
 tin. When the metal has dissolved, and the solution lost 
 its purple colour, the addition of common salt throws down 
 a yellow precipitate, which is collected, pressed, and the 
 colouring matter extracted by alcohol. It dyes silk and 
 wool of a yellowish-orange colour, but it easily oxidises 
 and becomes red. 
 
 Diazoamidobenzene and amidodiphenylimidc, C 12 H n N 3 , are 
 isomeric compounds obtained by the action of nitrous acid 
 on an alcoholic solution of aniline, the former at ordinary 
 and the latter at higher temperatures. Diazoamidobenzene, 
 or azodiphenyldiamine, crystallises in golden-yellow shining 
 
430 D YEING AND CALICO PRINTING. 
 
 laminae, which are sparingly soluble in cold alcohol, and 
 insoluble in water. The isomeric amidodiphcnylimide is 
 a yellow crystalline powder which is identical with the 
 product which Schiff* obtained by heating to 21 2° F. 1 part 
 of aniline nitrate dissolved in 10 of water, with 3 of 
 sodium stannate. A reaction takes place, which may be 
 considered to be complete when a sample of the liquid 
 turns red on the addition of an acid. It is then allowed 
 to cool, the stannic oxide removed by hydrochloric acid, 
 and the residue purified by repeated solution in dilute 
 boiling hydrochloric acid, and precipitation with ammonia. 
 Its solutions, when slightly acidulated, dye silk and wool 
 a deep lemon-yellow colour. The picrate gives a red 
 shade. It yields a blue dye when heated with aniline. 
 
 It is a curious circumstance that both these isomeric 
 aniline yellows are volatile, and may be removed from 
 the dyed fabrics by the mere application of heat. This 
 necessarily interferes considerably with their application 
 in dyeing. 
 
 Zinaline is the name given by Vogel to a yellow dye 
 obtained by the action of nitrous acid on solutions of 
 rosaniline. It is slightly soluble in boiling water, mode- 
 rately soluble in hot alcohol, and dyes wool and silk a 
 pale orange, which is changed to red by ammonia. It 
 dissolves in concentrated acids with a yellow colour, and 
 with alkalis it gives a bright red solution, from which acids 
 precipitate the zinaline unchanged. This substance, to 
 which Vogel assigns the formula C 20 H 19 N 2 O 3 , melts below 
 212 F., and at a higher temperature gives off abundant 
 yellow vapours, and then takes fire with slight detonation. 
 
 A substance which dyes silk and wool of a beautiful 
 golden-yellow colour is also obtained from the mother 
 liquors of magenta made by the nitrate of mercury pro- 
 cess, after the red has been precipitated by common salt. 
 
 *Compt. Rend., lvi., 1234. 
 
ADUL TEE A TION OF ANILINE YELL OW. 431 
 
 It is sparingly soluble in boiling water, readily soluble 
 in alcohol. 
 
 Jacobsen obtains a yellow colouring matter by the 
 action of 4 parts of mercurous nitrate on 10 of aniline 
 hydrochloride dissolved in 40 of water. After 24 hours 
 the precipitate is redissolved in boiling water, which, on 
 cooling, deposits it in a state of purity. 
 
 Adulterations. — The colours which come into the market 
 as aniline yellow and aniline orange are mostly mixtures 
 of yellow and red colouring matters. Naphthalene yellow 
 and nitrophenol are often sold as aniline yellow, and will 
 be found on examination to consist principally of picric 
 acid or naphthalene yellow. Many of these mixtures may 
 be detected by microscopical examination, or by treating 
 the sample with cold water. The chief adulterant is picric 
 acid, which may be readily recognised by its yielding the 
 purple isopurpuric acid when treated with potassium 
 cyanide, and when treated with chloride of lime, chloro- 
 picrin, which makes itself known by its characteristic 
 pungent odour. Chrysaniline generally contains arsenic, 
 in some cases to the extent of 5 per cent, or more. The 
 presence of picric acid is a decided evil, as it not only 
 diminishes the brilliancy of the yellow colour, but acts 
 prejudicially in other ways. 
 
CHAPTER XV. 
 
 Aniline Brown.— Aniline Black. 
 
 Aniline Maroons and Browns. — These colours are 
 only of secondary importance in dyeing. One of the first 
 patents taken out for them was that of Messrs. Girard and 
 De Laire for the production of a maroon. To 4 parts 
 of dry aniline hydrochloride in a state of fusion, 1 part of 
 dry magenta is added, and as soon as this is completely 
 dissolved the temperature is raised as rapidly as possible to 
 465 R, the point of ebullition of the hydrochloride, at 
 which it is maintained until the violet-red coloured mass 
 suddenly becomes a maroon. This point is usually reached 
 in the course of one or two hours ; yellowish vapours of a 
 peculiar alliaceous odour, recalling that of phenyl cyanide, 
 making their appearance just before the change above- 
 mentioned takes place. The colour is soluble in water, 
 alcohol, and acids, and may be employed directly for 
 dyeing, or it may be purified by precipitating its aqueous 
 solution with common salt. It gives rich shades on silk, 
 and also on leather. It is not improbable that this colour- 
 ing matter is an impure chrysotoluidine derivative. 
 
 Schultz prepares a fine garnet colour by passing a cur- 
 rent of nitrous acid into finely divided rosaniline, suspended 
 in a solution of soda or ammonia. It dyes wool, silk, 
 and mordanted cotton full rich shades, varying from puce 
 to garnet. 
 
 There is also a brown met with in commerce, manu- 
 factured from phenylenediamine by treating it with an 
 alkaline nitrite. The phenylenediamine for this purpose is 
 
ANILINE BROWNS. 433 
 
 prepared by submitting dinitrobenzene to the action of tin 
 and hydrochloric acid. 
 
 Jacobson prepares browns by the action of oxidising 
 agents on rosaniline. One process consists in heating 
 aniline formate to 21 2° F. with a strong solution of ammo- 
 nium chromate; in the other, picric acid is heated in a 
 capacious vessel with two parts of commercial aniline. 
 At first the picric acid dissolves, forming an orange-yellow 
 oily liquid, but as the temperature rises it becomes brown, 
 and at 230 to 240 F. evolves abundance of vapours. It 
 should be kept at 280 to 300 F. until ammoniacal vapours 
 cease to be given off, and a small portion thrown into water 
 communicates but a faint yellow colour to the liquid ; this 
 usually takes some hours. The black mass is then poured 
 with constant stirring into dilute hydrochloric acid, and in 
 order to remove all the unaltered aniline and also a red 
 colouring matter which is present, it is ground up and 
 boiled repeatedly with successive portions of very dilute 
 acid. It is finally collected, and washed first with an alka- 
 line solution, and then with pure water. 
 
 This dye is insoluble in water, but if too high a tempera- 
 ture has not been employed in its preparation, it is 
 completely soluble in alcohol. Its alcoholic solution is 
 acidulated with sulphuric acid and mixed with glycerin, 
 before it is added to the bath. 
 
 The crude colour may also be purified by dissolving it 
 in concentrated sulphuric acid, pouring the solution into 
 water, and precipitating with common salt. As thus pre- 
 pared it is somewhat more readily soluble in alcohol. 
 
 This colour dyes silk a Corinth red, and wool a deep 
 brown with a violet reflection. 
 
 M. H. Koechlin employs the brown colouring matter 
 
 noticed by Hofmann when studying the action of oxidising 
 
 agents on rosaniline. These colours may be fixed on wool 
 
 by printing a mixture of gum water with 2 parts of oxalic 
 
 DD 
 
434 DYEING AND CALICO PRINTING. 
 
 acid and I of potassium chlorate, to which an alcoholic 
 solution of magenta, containing 50 grammes to the litre, is 
 added. The shade of brown may be altered by employing 
 less oxalic acid and chlorate — this causes it to have a 
 redder tinge. By adding neutral extract of indigo, any 
 shade of colour up to black may be obtained. 
 
 This brown may also be fixed on cotton by means of albu- 
 men: it is prepared for this purpose by acting on magenta 
 with hydrochloric acid and potassium chlorate. The pro- 
 duct, which is insoluble in water, after being thoroughly 
 washed, is ready for use. It is soluble in alcohol and in 
 concentrated sulphuric acid, from both of which solutions 
 it is precipitated by water. 
 
 Wise prepares a brown in the following manner : a mix- 
 ture of equal parts of rosaniline and formic acid — to which 
 may be added half a part of sodium acetate — is heated for 
 several hours to a temperature which may vary from 
 290 to400° F. It then forms an orange-red coloured mass, 
 which, when cold, is thoroughly mixed with three parts of 
 aniline and again heated for an hour or two, this time to 
 about 445 F. When the reaction is complete, the brown- 
 coloured product is dissolved in dilute hydrochloric acid, 
 and the colouring matter precipitated by common salt. 
 
 Sieberg prepares a brown dye by the action of aniline 
 on the mixture of crude violaniline, mauvaniline, and 
 chrysotoluidine obtained as an insoluble residue in the 
 magenta manufacture. For this purpose 10 lbs. of the 
 residue are added to 20 lbs. of fused aniline hydrochloride, 
 and the mass heated until the brown colour is fully 
 developed, which may be ascertained by dissolving a sam- 
 ple in alcohol. As soon as the reaction is complete, the 
 product is poured with constant agitation into 50 gallons 
 of boiling water, in which 40 lbs. of crystallised carbonate 
 of soda has been dissolved. The insoluble brownish-black 
 tarry mass thus obtained is repeatedly washed with water. 
 
ANILINE BLACK. 
 
 435 
 
 In order to prepare it for use, 5 lbs. of the dye are dissolved 
 in 4^ gallons of alcohol, and 6}i gallons of water are 
 added, with constant stirring. It is then put aside to settle, 
 and the clear brown solution decanted. 
 
 Most of the aniline browns are soluble in boiling water, 
 and may be used directly for dyeing. No mordant is re- 
 quired for dyeing wool or silk: with cotton, albumen is 
 employed, and also processes similar to those already 
 described when treating of the other aniline colours. A 
 yellower shade can in most cases be obtained by employing 
 a small amount of picric acid ; whilst for a redder shade 
 magenta may be added to the bath. 
 
 ANILINE BROWN. 
 
 Aniline Black. — This colouring matter is of a very 
 indefinite nature, and differs remarkably from the other 
 aniline colours previously described, as it is quite insoluble 
 in water and alcohol, in soap lye, and in acid or alkaline 
 solutions, so that it has to be formed on the fibre itself. 
 It gives a deep velvety shade on cotton, whicli is cnangec 
 to a dull green by the action of acids, and restored again 
 to its original colour by alkaline solutions. HDilute solu- 
 tion$ of potassium dichromate intensify the colour, and 
 
436 DYEIXG AXD CALICO PRINTING. 
 
 hypochlorites slowly destroy it. If, however, an aniline 
 black be submitted to the action of a solution containing 
 a hypochlorite merely until it acquires a red shade, and 
 is then washed and exposed to the air, it slowly becomes 
 black again. 
 
 The processes for printing aniline black are very 
 numerous and varied, the earliest being that employed 
 by Mr. J. Lightfoot, of Accrington, in i860, and for which 
 a French patent was taken out in January, 1863. The 
 peculiarity of this colour is, that it does not exist when 
 printed on the fabric, but is gradually developed by the 
 reactions which take place between the various substances 
 composing the mixture that is printed. The first mixture 
 employed consisted of: — 
 
 Starch 1 y 2 lbs. to 1 gallon of water 
 
 Aniline 8 ounces 
 
 Hydrochloric acid 8 „ 
 
 Ammonium chloride 4 „ 
 
 Xitrate of copper solution (88° T\v.) ... 2 „ 
 Chlorate of potassium 4 „ 
 
 In the patent of 1863 this was considerably modified, the 
 mixture to be printed consisting of: — 
 
 Aniline 8 ounces 
 
 Hydrochloric acid 8 „ 
 
 Acetic acid 20 „ 
 
 Perchloride of copper (SS° Tw.) 8 „ 
 
 Ammonium chloride 4 „ 
 
 This was mixed with 1 gallon of starch paste containing 
 4 ozs. of chlorate of potassium in solution; or, if used 
 for dyeing, the thickening could be omitted. The dyed or 
 printed goods were then aged for three days, washed, and 
 soaped, or passed through a dilute solution of chloride of 
 lime, whereby an intense black was produced. During the 
 ageing, the acid decomposes the chlorate of potassium, and 
 the liberated chloric acid and the cupric chloride, reacting 
 
ANILINE BLACK. 437 
 
 on the aniline, produce the insoluble aniline black which 
 remains fixed on the tissue. 
 
 The beauty and lustre of the black thus obtained caused 
 it to be extensively adopted in England, France, Switzer- 
 land, and Germany ; but the excess of acid and the copper 
 chloride attacked the rollers and doctors of the printing 
 machines so strongly, that the process fell into disfavour. 
 Moreover, the mixture would not keep for any length of 
 time at the ordinary temperatures, the reaction which pro- 
 duces aniline black taking place in the mixture itself, so 
 that the colour, being no longer formed on the fibre itself, 
 would not adhere. It is still used, however, for block 
 printing. 
 
 Lauth succeeded in obviating this inconvenience by 
 substituting the insoluble sulphide of copper for the acid 
 chloride of copper, and in January, 1865, took out a patent 
 for the new process. 
 
 Water 5 litres 
 
 Starch 1000 grammes 
 
 Sulphide of copper 250 „ 
 
 This mixture was boiled, and allowed to cool. In the 
 meantime a second mixture was prepared containing: — 
 
 Water 1850 grammes 
 
 Torrefied starch 1 200 
 
 Gum water 1000 
 
 Aniline hydrochloride 800 
 
 Chloride of ammonium 100 
 
 Chlorate of potassium 300 
 
 When cold, the two mixtures were thoroughly incor- 
 porated, and printed in the usual manner. The black was 
 developed by ageing for 24 hours at about 70° F. and then 
 washing thoroughly. In this mixture, the sulphide of 
 copper is gradually converted into sulphate by the oxidis- 
 ing action of the hydrochloric acid and potassium chlorate, 
 and then acts as the chloride of copper does in Lightfoot's 
 
43 S DYEING AND CALICO PRIXTIXG. 
 
 mixture. As the soluble salt of copper does not exist in 
 the mixture when printed, but is only formed gradually on 
 the fibre, it does not affect the rollers and doctors; more- 
 over, the mixture can be kept for a considerable length of 
 time in a cool place. 
 
 The sulphide of copper for this purpose is prepared by 
 precipitating a hot solution of sulphate of copper, with 
 sodium sulphide made by boiling flowers of sulphur in a 
 solution of caustic soda. The black precipitate merely 
 requires to be collected and washed, to be ready for use. 
 
 The nature of the acid which enters into the composition 
 of the aniline salt is not a matter of indifference : neither 
 the acetate nor the citrate give good blacks, whilst both 
 the hydrochloride and nitrate give good results. The more 
 acid the aniline salt is, the more rapidly does the colour 
 develope, and the deeper is the shade ; unfortunately, when 
 a great excess of acid is used, it not only attacks the 
 rollers but also injures the fibre. 
 
 M. C. Koechlin has modified Lauth's process by substi- 
 tuting tartrate of aniline for the hydrochloride; this has 
 not only the advantage that it can be applied to the most 
 delicate tissues, but it does not attack the mordants for 
 other colours with which it may be mixed in printing. 
 Koechlin's formula is : — 
 
 Water 10 litres 
 
 Starch 2 kilos 
 
 Torrefied starch 2 ., 
 
 Aniline 2 „ 
 
 Chloride of ammonium 4 n 
 
 Chlorate of potassium 1 ., 
 
 Boil together until the mixture is homogeneous, and when cold 
 add 1 kilo of sulphide of copper paste and 2 kilos of tartaric acid. 
 
 M. Sacc has succeeded in obtaining deep olive-browns 
 with the following mixture : — 
 
AXILIXE BLACK. 439 
 
 Water 300 grammes 
 
 Starch 36 „ 
 
 Aniline 20 „ 
 
 Chlorate of potassium 15 „ 
 
 Acetate of copper 15 „ 
 
 Nitric acid 10 „ 
 
 Dullo has proposed to employ a paste prepared by 
 mixing 100 grammes of aniline, 80 of hydrochloric acid, 
 10 of black oxide of manganese, and 1 litre of water. 
 The colour, which is green at first, is changed to black by 
 the action of ammonia. 
 
 The action of oxide of manganese on an acid salt of 
 aniline has been taken advantage of by Lauth, who pro- 
 poses to dye or print vegetable fabrics or yarns by first 
 applying a salt of manganese, and then passing the goods 
 through a bath of dilute caustic soda to precipitate the 
 manganous oxide; this is finally converted into peroxide 
 by treatment with chloride of lime. The mordanted 
 pieces or yarn, after being thoroughly washed, are im- 
 mersed in a bath of aniline salt containing 50 grammes 
 of aniline, 100 of hydrochloric acid, and 150 of sulphuric 
 acid to the litre of water. The mordanted parts then 
 acquire a greenish hue, which becomes black when passed 
 through a bath of soap lye, or weak alkali. Treatment 
 with a dilute solution of potassium dichromate, or with a 
 mixture of potassium chlorate, ammonium chloride, and 
 sulphate of copper (1 gramme of each to the litre) inten- 
 sifies the colour. The goods are finally washed and boiled 
 with soap. In order to dye wool, silk, or other animal 
 substances, the peroxide of manganese mordant is de- 
 posited by immersing them in a bath of weak manganate 
 or permanganate of potassium, and then dyeing them in 
 the manner just described. This process gives a very 
 brilliant black, but the mordanting is troublesome, and the 
 dye is apt to rub off a little. 
 
440 DYEING AND CALICO PRINTING. 
 
 The following recipes, the two first of which are by Mr. 
 Spirk, may also be found useful: — 
 
 Water 6 litres 
 
 Aniline i ooo grammes 
 
 Chlorate of potassium 625 „ 
 
 Chloride of ammonium 625 „ 
 
 Boil for a quarter of an hour, and, when nearly cold, add 1000 
 grammes of tartaric acid dissolved in 1 litre of water, stirring all 
 the time. 
 
 To prepare this for use add 135 grammes of starch and 135 of 
 dextrin to 1 litre of the mixture, and boil until dissolved; then, 
 just before printing, add 60 grammes of sulphide of copper. 
 
 Water 3 litres 
 
 Starch 150 grammes 
 
 Tragacanth 7^ „ 
 
 Dextrin 42 „ 
 
 Potassium chlorate 90 „ 
 
 Ammonium chloride 75 „ 
 
 Boil until dissolved; when cold add 240 grammes of aniline, and, 
 just before printing, 75 grammes of sulphide of copper. 
 
 Water 6 litres 
 
 Starch 300 grammes 
 
 Tragacanth 150 „ 
 
 Torrefied starch 750 „ 
 
 Potassium chlorate 200 „ 
 
 Boil until dissolved; when cold add 400 grammes of aniline 
 
 hydrochloride, and, just before printing, 200 grammes of sulphide 
 of copper. 
 
 Starch solution 5 litres 
 
 Dextrin solution 5 „ 
 
 Tragacanth solution 5 „ 
 
 Potassium chlorate 500 grammes 
 
 Aniline hydrochloride 1 000 „ 
 
 Before printing incorporate 330 grammes of sulphide of copper. 
 
ANILINE BLACK. 441 
 
 The printed goods, after ageing for 24 to 48 hours at a 
 temperature of about 8o° R, are passed, first through an 
 alkaline bath at 170 R, and then through a soap bath. 
 If the whites are dull, they may be brightened with weak 
 bleaching liquor. 
 
 An aniline black paste, to be used for printing with 
 albumen, may be prepared by warming to about 140 F. 
 a solution of 40 grammes of potassium chlorate, 32 of 
 ammonium chloride, 80 of sulphate of copper, and 80 of 
 aniline hydrochloride in a litre of water. In a few minutes 
 a powerful reaction sets in, and the mixture froths up. It 
 is now left to itself for a few hours, and if the black is not 
 fully developed it is again heated to 140 R, and then 
 exposed in an open place for a day or two. It must be 
 carefully washed until it is quite free from soluble salts. 
 It is then ready for use. 
 
 Jarosson and Miiller have patented a process for aniline 
 black in which iron chloride is substituted for the copper 
 salt usually employed, the cloth being mordanted with it 
 by immersion in a bath prepared by dissolving 6 lbs. of 
 iron in 2 gallons of water and 20 lbs. of hydrochloric acid, 
 and then diluting it with water until it has a density of 
 12° Baume. It is then aged for 12 hours. The mordanted 
 calico or yarn is then winced in a bath containing for each 
 60 lbs. of cotton 6 lbs. of aniline and 10 lbs. of hydro- 
 chloric acid, to which is added a solution of 4 lbs. 3 ozs. 
 of potassium chlorate in 6 gallons of water. The cloth 
 is then heated for 3 to 5 hours in a closed vessel to a 
 temperature of 90 R, which is gradually raised to 120 R, 
 and the colour finally fixed by a bichromate bath. 
 
 Schlumberger has proposed to print aniline black with a 
 mixture made by adding 10 per cent, of moist aniline 
 ferrocyanide to a thickened mixture of aniline chlorate. 
 The aniline ferrocyanide for this purpose is prepared by 
 mixing 2 kilos of aniline with 2 kilos of hydrochloric acid 
 
442 DYEIXG AXD CALICO PRINTING. 
 
 of 19/ Baume, and then adding it to a solution of 2*4 kilos 
 of potassium ferrocyanide in 4*2 litres of water. The 
 ferrocyanide should be dissolved in the water by boiling, 
 and as soon as it has cooled to 1 35° F. the aniline salt must 
 be added. When it is quite cold, the crystalline pulp of 
 aniline ferrocyanide is thrown on a filter and allowed to 
 drain. It should weigh about 47 kilos. It has the 
 inconvenience that it cannot be kept long, for it quickly 
 acquires a violet colour, especially if exposed to light. 
 
 The composition of aniline black is not known, neither 
 is its mode of formation thoroughly understood. It seems 
 probable, however, that it consists of two colours, one a 
 brown-black, produced by the action of the chlorinating 
 agents on the aniline salt; the other, an intense violet 
 blue-black, is, perhaps, a product of the oxidation of the 
 aniline salt. The former is the most stable, resisting the 
 action of almost all chemical agents; whilst the latter, 
 although it resists soaping, is turned green by a trace of 
 free acid. These two colours combined form ordinary 
 aniline black. 
 
 According to Brandt, the composition of the aniline 
 blacks fixed upon fibrous materials differs greatly according 
 to the process employed, as is evident from the manner in 
 which they withstand the action of light and of chemical 
 reagents. The more intense the black, the better does it 
 resist the agents which are likely to produce this change. 
 A black which has been formed in the presence of an 
 excess of aniline is always faster than one formed where 
 the acid is in excess, the latter being apt to turn green. 
 As, however, potassium chlorate decomposes but slowly in 
 the presence of an excess of aniline, it is advisable to 
 substitute for it, in this case, aniline chlorate; the develop- 
 ment of the colour also takes place much more rapidly, 
 since the chlorate of aniline itself is applied to the 
 cloth, instead of being formed by double decomposition 
 
ANILINE BLACK. AA% 
 
 between the aniline hydrochloride, and the potassium 
 chlorate. 
 
 Some aniline blacks resist the action of chemical agents 
 extremely well, whilst others readily turn olive-green in 
 contact with air containing sulphurous fumes, so that if the 
 gas, used in a warehouse where goods dyed or printed with 
 aniline black are stored, should contain a little sulphur, the 
 folds of all the pieces will be turned green, more or less, by 
 the sulphurous anhydride produced. 
 
 Aniline black may be considered as the result of the 
 mixture of colours produced by two different reactions, 
 namely, the decomposition of the aniline chlorate and of 
 the oxidation of the aniline itself. By the decomposition of 
 the aniline chlorate, chlorinated substitution products of 
 aniline are formed, and the various degrees of substitution 
 which may take place would offer a probable explanation 
 of the different results obtained. 
 
 The presence of copper has generally been regarded as 
 essential to the production of aniline black, but Mr. Light- 
 foot has recently ascertained that there are a few other 
 metals which are capable of replacing it in this curious 
 reaction. The manner in which the experiments were 
 carried out was by printing a thickened mixture of 
 ammonium chlorate and aniline hydrochloride, containing 
 excess of aniline, on well bleached cotton by means of a 
 wooden roller. The fabric thus prepared was brought, 
 whilst still damp, in contact with various metals, and 
 allowed to remain for a quarter of an hour, after which it 
 was hung up in a warm moist atmosphere for twelve hours, 
 and then passed through an alkaline bath. The metals 
 tried were copper, iron, vanadium, uranium, nickel, lead, 
 zinc, antimony, tin, manganese, chromium, bismuth, arsenic, 
 titanium, tungsten, cadmium, molybdenum, mercury, silver, 
 gold, platinum, palladium, rhodium, iridium, osmium, 
 ruthenium, cobalt, aluminium, magnesium, thallium, lithium 
 
444 DYEING AND CALICO PRINTING. 
 
 lanthanum, didymium, erbium, yttrium, tantalum, and 
 niobium, also selenium and tellurium. The result showed 
 that the best black was produced by vanadium, the next 
 best by copper, then uranium, and lastly iron. The other 
 metals gave but little colour, or none at all. 
 
 It has been found that all the aniline blacks believed to 
 be formed in those processes in which copper salts are not 
 employed, owe their formation to the presence of that metal 
 in the vessels in which the mixtures have been prepared, or 
 to the use of copper or bronze rollers in printing; the 
 merest trace of copper being sufficient to produce a black 
 colour, although a larger quantity greatly facilitates its de- 
 velopment. Mr. Lightfoot found that a sovereign or a 
 shilling which had no effect on his printed calico, after 
 having been violently shaken in a bag with some copper 
 coins, produced a change; the gold coin giving a grey mark, 
 and the silver one an almost black tint. 
 
 It has also been thought that the presence of chloride of 
 ammonium was essential to the formation of the colour, 
 but Rheineck has prepared aniline black without the use 
 of ammonia, by mixing equal weights of aniline, hydro- 
 chloric acid, and potassium chlorate, with a minute quantity 
 of chloride of copper, and a sufficient quantity of water, 
 and allowing the solution to evaporate spontaneously. 
 The black powder thus produced, after being thoroughly 
 washed with water, left no residue on ignition. 
 
 According to Rheineck, aniline black is a powerful base, 
 to which he gives the name of nigraniline. When a cotton 
 fabric is immersed in a solution of aniline hydrochloride 
 and potassium chlorate, containing a little cupric chloride, 
 and then exposed to the air, it acquires a dark green colour, 
 which on treatment with alkalis changes to a violet-black. 
 The dark green compound is the hydrochloride of the base, 
 from which the hydrochloric acid may be removed by soda 
 or ammonia, leaving the black base. This base is more 
 
ANILINE BLACK. 44$ 
 
 powerful than aniline, and expels it from its salts ; so that if 
 a piece of cotton lightly dyed as above described, and then 
 treated with an alkali, be immersed in a solution of aniline 
 hydrochloride, it immediately takes a green tinge, even if 
 the aniline is in excess. A piece of cotton moderately 
 coloured with aniline black is a good test for the presence 
 of free acids or alkalis, and the same piece may be used 
 several times without losing its sensitiveness. When turned 
 green by an acid, it should be well washed with distilled 
 water, after which it will be found to change to violet when 
 immersed even in a very feeble alkaline solution, such as 
 spring water. When the greenish-black precipitate ob- 
 tained by Rheineck's method is treated with concentrated 
 sulphuric acid, it gives off hydrochloric acid, and yields a 
 violet-coloured solution ; on evaporation this leave a green- 
 black residue apparently the sulphate of the base. 
 
 In dyeing with aniline black, the nature of the aniline, as 
 in the preparation of the other aniline colours, is a matter 
 of considerable importance, neither pure aniline nor pure 
 toluidine giving satisfactory results. The aniline oils 
 usually employed for this purpose may be separated by 
 fractional distillation into four portions. 
 
 1. About 60 to 65 per cent, of nearly pure aniline, boil- 
 ing at 356 to 365 F. 
 
 2. About 18 to 22 per cent, of a mixture of aniline and 
 toluidine, boiling at 365 to 378 F. 
 
 3. About 8 or 9 per cent, of nearly pure toluidine, boil- 
 ing at 378° to 388° F. 
 
 4. From 4 to 6 per cent, of residue, boiling above 388 F., 
 and consisting of xylidine, cumidine, &c. 
 
 The specific gravity of these fractions is as follows : — 
 
 1. From 2°. 7 5 to 3° '.4 Baume. 
 
 2. „ i°.6 to 2°. 1 
 
 3. ,, o°.6 to i".o 
 4- „ °°-5 
 
446 DYEING AND CALICO PRINTING. 
 
 Pure aniline oil of Coupier has a density of 3°.5 Baume; 
 ordinary toluidine o°.88 ; and pseudotoluidine o°.5o. Pure 
 aniline oil of Coupier, and anilines boiling at temperatures 
 varying from 3 5 6° to 365 ° F., yield intense and brilliant 
 blacks. Pseudotoluidine and the products boiling at 365 
 to 378 F., also give good blacks, but with a blue shade. 
 Ordinary toluidine of Coupier, and fractions of aniline oil 
 boiling above 378° F., give unsatisfactory shades between 
 brown and black. 
 
 As toluidine, which is decidedly injurious to the colour if 
 present in too large a quantity, has a comparatively low 
 density, it will be evident that the specific gravity of the 
 oil affords important indications of its value for the pro- 
 duction of aniline black. If the specific gravity of the oil 
 is above 3°. 5 Baume, it will generally be found to contain 
 nitrobenzene. Anilines of 3°.5 to 2° Baume give satisfac- 
 tory blacks, whilst if below 2° it contains too much toluidine. 
 
 Although this method of testing the value of the aniline 
 has the advantage of simplicity and rapidity, much more 
 accurate results may be obtained by submitting the sample 
 to fractional distillation, and noting the amount which dis- 
 tils over between 355° and 375° F. 
 
 Hartmann estimates the value of a given sample of 
 aniline by observing the yield of black dye which it gives 
 as compared with that obtained from a known quantity of 
 Coupler's aniline. 
 
 Although it had long been known that bichromate of 
 potassium has a very powerful action upon certain aniline 
 salts if the solution is sufficiently concentrated, producing 
 a black precipitate, yet none of the attempts to render this 
 available for dyeing black have hitherto been successful. 
 Thus, if the mixed solution of the aniline salt and bichro- 
 mate is very dilute, the fabric immersed in it is not dyed at 
 all ; whilst, if concentrated, a black precipitate soon makes 
 its appearance in the bath. Attempts were made to 
 
ANILINE BLACK. 447 
 
 obviate this inconvenience by cooling the solutions to the 
 freezing point, but, as aniline chromate is comparatively 
 insoluble at a low temperature, it crystallised out if the 
 solutions were sufficiently concentrated to produce the 
 colour, and, being deposited on the cloth, caused the 
 formation of spots. Moreover, when the piece was 
 removed from the bath and the temperature rose, there 
 was danger of its being burnt in the neighbourhood of the 
 spots, from the heat evolved in the decomposition of the 
 aniline chromate. 
 
 M. J. Persoz has overcome these difficulties by the simple 
 expedient of exposing the tightly stretched cotton fabric 
 to the spray of solutions of an aniline salt and of potassium 
 bichromate, which are separately applied to the cloth by 
 means of a horizontal brush, to which a reciprocating 
 motion is communicated in a vertical direction. These 
 solutions, which may be thus applied either successively or 
 simultaneously, become intimately mixed in the fabric 
 itself, where the reaction takes place which results in the 
 production of the black. The cloth has at first a very 
 dark green colour, which changes to a pure black when 
 washed and passed through a soap bath. By printing the 
 fabric with resins or fats previous to dyeing it in this way, 
 white patterns on a black ground may be obtained. 
 
 Persoz found that neutral salts of aniline do not give 
 good results, neither do salts of organic acids, such as the 
 acetate or oxalate; the best aniline salts for the purpose 
 being the biacid salts. The sulphates give a reddish-black, 
 and the hydrochlorides and nitrates a black with a violet 
 or blue shade. As might be expected, a mixture of equal 
 volumes of the bisulphate and bihydrochloride gives 
 excellent results, It is necessary to employ a rather con- 
 centrated solution of bichromate of potassium, containing 
 not less than 8 per cent, of the salt. 
 
 Aniline black is much valued for printing on cotton 
 
443 DYEIXG AXD CALICO PRINTING. 
 
 ANILINE BLACK. 
 
 on account of its brilliancy and fastness. It acquires a 
 greenish hue by long exposure to air and light, but the 
 original colour is restored by treatment with alkaline solu- 
 tions, or by washing with soap. Considerable difficulties 
 have hitherto been met with in dyeing silk and wool with 
 this colour, but in 1S65 Mr. Lightfoot patented a process 
 for treating wool, by which it was rendered capable of 
 taking up aniline black. A solution is prepared with 1 lb. 
 of chloride of lime to 1 gallon of water, and the wool is 
 immersed at ioo = F. in a bath of 30 gallons of water, 7 lbs. 
 of solution of chloride of lime, and 1 lb. of hydrochloric 
 acid, and worked in it until it acquires a yellowish tinge. 
 It is then thoroughly washed, and is ready for dyeing by 
 Lauth's or Lightfoot's process. 
 
 According to Lauber, an aniline grey may be printed on 
 cotton by the following process: — 
 
 In 3*5 litres of water 625 grammes of potassium chlorate 
 are dissolved, and on cooling the following materials are 
 stirred in: 6'5 litres of gum water to 1 kilo; 3125 grammes 
 of ammonium chloride; 1500 grammes of potassio-chromic 
 tartrate of 30" Baume; 200 grammes of aniline; and n 60 
 
CASTHELAZ GREY. 449 
 
 grammes of tartaric acid. The whole is well stirred up 
 until the salts are completely dissolved. 
 
 The potassio-chromic tartrate is prepared by dissolving 
 960 grammes of potassium dichromate in 3 litres of boiling 
 water, and when the solution has cooled to uo° R, adding 
 1,440 grammes of finely powdered tartaric acid. The 
 vessel is placed in cold water, so as to avoid any rise of 
 temperature, which might prove injurious. The printing 
 should proceed continuously, and not stop, in fact, until the 
 last piece leaves the dry plates. The pieces are hung up 
 for forty-eight hours in a warm room, the temperature of 
 which is about 105 F., then washed, dried, and finished. 
 Paler shades may be obtained by diluting the mixture with 
 gum water. 
 
 Casthelaz prepares an aniline grey by the action of 
 aldehyde on an acid solution of mauveine, but its price 
 hitherto has been very high. To prepare it, 10 lbs. of 
 mauveine paste are dissolved in 1 1 lbs. of concentrated 
 sulphuric acid 66° Baume: 6 lbs. of aldehyde are gradually 
 added, and the whole left to stand for four or five hours. 
 It is then poured into water, the solution filtered, and the 
 colouring matter precipitated by common salt. It may 
 easily be purified by successive solutions and reprecipitations. 
 
 To prepare it for printing, one part of the solution of 
 'Casthelaz grey' is mixed with four of reduction paste made 
 by boiling I gallon of acetate of alumina, 1 gallon of 
 water, and 3 lbs. of starch until dissolved, and then adding 
 8 ozs. of arsenic dissolved in 1 pint of glycerin. The pieces 
 should be steamed for half an hour. 
 
 EE 
 
CHAPTER XVI. 
 
 PHENOL, CRESOL, AND NAPTHALENE COLOURS. 
 
 Besides the numerous beautiful dyes which have been 
 described in the previous chapters as derived from aniline 
 and its homologues, there are others, which, although not 
 'aniline colours,' have been prepared from products ob- 
 tained in the distillation of coal-tar. It is the object of 
 the present chapter to notice briefly the various compounds 
 in coal-tar which yield these colours, and also to describe 
 the mode of preparation of the most important of the 
 latter. 
 
 PHENOL. — This substance, which is known also by the 
 name of carbolic acid or coal-tar creosote, was discovered 
 in coal-tar by Runge, and was afterwards obtained in larger 
 quantity and carefully examined by Laurent, and by 
 Williamson and Scrugham. The first, however, to manu- 
 facture it on a large scale was Dr. E. Sell, a German 
 chemical manufacturer at Offenbach, who introduced it as 
 a substitute for creosote. 
 
 Phenol may be extracted both from the light coal-tar 
 naphtha, and also from that portion of the oil which distils 
 between 300 and 400 F. by agitating them with milk of 
 lime or a solution of soda, the former source yielding the 
 purer article. After separating the clear solution from the 
 neutral oils, and neutralising it with an acid, the impure 
 phenol is obtained as an oily layer, which is submitted to 
 fractional distillation. The portions which come over 
 between 360° and 368 F., when well cooled, form a mass of 
 crystals, from which the fluid portions may be removed by 
 
PHENOL. 45 1 
 
 draining and pressure, or by means of a centrifugal machine. 
 If a very pure phenol is required, it is advisable to repeat 
 the solution in alkali and precipitation with an acid before 
 the final rectification. This precipitation should be made 
 fractionally, the first portions which are thrown down con- 
 taining all the naphthalene and most of the cresol, whilst 
 the subsequent fractions consist of almost pure phenol, 
 which will crystallise after one rectification, if a crystal of 
 the substance be added to the distillate when cold. 
 
 Phenol, C G H 6 or C c H 5 .OH, crystallises in long colour- 
 less needles, which melt at 108 F., and boil at 359'6° F. It 
 is moderately soluble in water, and forms with it a crystal- 
 line hydrate, 2C 6 H 6 + OH,, in large six-sided prisms, 
 which melt at 93 F. When a small quantity of water is 
 added to crystalline phenol, it takes it up and becomes 
 an oily liquid. It is miscible in all proportions with 
 alcohol, ether, and strong acetic acid. 
 
 Phenol is very closely allied to aniline and to benzene, 
 C 6 H 6 : it may be regarded as derived from the latter by 
 the replacement of one atom of hydrogen by the group 
 OH, thus: C a H O = C G H 5 .OH. This atom of hydrogen 
 is replaceable by metals, so that when treated with an 
 alkali, such as potassium hydrate, the hydrogen is replaced 
 by potassium. 
 
 QH 5 .OH + KHO = C 6 H 3 .OK + OH 2 . 
 
 Phenol. Potassium- 
 
 phenate. 
 
 The compounds, with the metals of the alkalis and the 
 alkaline earths, are very readily soluble in water; advantage 
 is taken of this in the process of extracting phenol from 
 coal-oil by agitating it with an alkaline solution : the sodium 
 or calcuim phenate dissolves, and on the addition of an acid 
 to the solution, it is decomposed ; a sodium or calcium salt 
 being formed, whilst the phenol separates as an oil if the 
 solution is sufficiently concentrated. 
 
452 DYEING AND CALICO PRINTING. 
 
 Picric acid. — Picric acid, carbazotic acid, or trinitrophenol 
 is the most important of the compounds obtained from 
 phenol by the action of nitric acid on it. When phenol is 
 treated with dilute nitric acid, taking care that no great 
 elevation of temperature occurs during the reaction, a deep 
 brown tarry mass is obtained, from which two isomeric 
 mononitrophenols C 6 H 5 (N0 2 )0, may be obtained; one of 
 these crystallises in yellow needles, which are readily vola- 
 tile in the vapour of water; the other forms colourless 
 needles, which are not volatile at 21 2° F. By the further 
 action of nitric acid on these compounds, another atom of 
 hydrogen may be displaced by the group N0 2 , and dinitro- 
 phcnols C 6 H 4 (N0 2 ) 2 are obtained. Finally, the long 
 continued action of nitric acid on any of these gives rise to 
 trinitrophenol or picric acid, C c H 3 (NO 2 ) 3 O, which may be 
 regarded as phenol in which three of the hydrogen atoms 
 have been displaced by NO... 
 
 Stenhouse's method of preparing this acid by the action 
 of nitric acid on the resin of the Xanthorrhcea Jiastilis, or 
 Australian 'yellow gum,' has been recommended by Cary 
 Lea as one of the best modes of making it. It is now, how- 
 ever, universally manufactured from phenol, which for this 
 purpose must be tolerably free from cresol, otherwise the 
 product will be contaminated with nitro derivatives of that 
 substance. 
 
 Concentrated nitric acid acts on phenol with extreme 
 violence, so that in preparing picric acid it is necessary to 
 operate with the dilute acid. Perra puts 6 parts of nitric 
 acid, of density 1.3, into a flask or other suitable apparatus, 
 furnished with a condensing tube, or cohobator, and 
 gradually adds 1 part of phenol. The nitric acid which is 
 volatilised, condenses and flows back into the flask, whilst 
 the nitrous fumes, which are generated in abundance, pass 
 off. Guinon allows phenol to drop slowly into flasks con- 
 taining nitric acid of specific gravity 1*3, and arranged in 
 
PICRIC ACID. 453 
 
 two rows on a sand bath. All these flasks communicate 
 by means of tubes, with a large stone-ware vessel to con- 
 dense the acid fumes. As soon as the drops of phenol no 
 longer produce a violent reaction when they fall into the 
 nitric acid, the supply is cut off, and a gentle heat is applied 
 by means of the sand bath, to dissolve the resinous mass 
 floating in the liquid. As soon as this is effected, the con- 
 tents of the flasks are poured into a crystallising vessel, 
 where the picric acid is deposited, partly in plates, and 
 partly as a resinous cake at the bottom. 
 
 In order to purify the crude picric acid, after it has been 
 collected and the acid mother liquor allowed to drain off 
 as far as possible, it is dissolved in boiling water previously 
 mixed with about one thousandth of sulphuric acid, and 
 then filtered from the yellow resinous matters which are 
 comparatively insoluble in the acid liquid. The picric acid 
 separates from the solution, on cooling, in crystalline plates 
 of a pale yellow colour. But these crystallisations cause 
 the loss of a considerable quantity of substance, and the 
 product is by no means free from tarry and resinous 
 matters ; moreover, the large quantity of water required to 
 dissolve the acid renders the filtrations inconvenient. 
 
 Another process is therefore very generally adopted 
 which consists in nearly neutralising a boiling solution of 
 picric acid with sodium carbonate, and filtering from the 
 resin, which is but very slightly soluble if the liquid be dis- 
 tinctly acid. On adding excess of sodium carbonate to 
 the filtrate, nearly the whole of the sodium picrate cyrstal- 
 lises out, being comparatively insoluble in strong solutions 
 of the carbonate. The nearly pure sodium picrate thus ob- 
 tained, after being freed as far as possible from adhering 
 mother liquor, is dissolved in boiling water, and decomposed 
 by a slight excess of sulphuric acid. The picric acid being 
 nearly insoluble in the strongly acid solution of sodium 
 sulphate, crystallises out almost entirely on cooling. After 
 
454 DYEING AND CALICO PRINTING. 
 
 being collected and washed with a little water, it is almost 
 chemically pure, provided sufficient water was taken in the 
 first instance to enable the sodium sulphate formed to re- 
 main in solution, otherwise some of this salt crystallises 
 out along with the picric acid. 
 
 Picric acid may also be very conveniently prepared by 
 acting with nitric acid on the phenolsulphonic acid obtained 
 by mixing phenol and sulphuric acid in equivalent pro- 
 portions; or, still better, by converting the phenolsulphonic 
 acid into a sodium salt, and then treating this with nitric 
 acid. 
 
 Picric acid crystallises in lustrous plates, which are of a 
 very pale yellow colour when pure. It melts at 252°.5 F., 
 and at higher temperatures gives off suffocating fumes, 
 and ultimately decomposes with a slight explosion. Its 
 solutions redden litmus, and it has a very bitter taste. It 
 dissolves in 86 parts of water at 59° F., and in 26 at 170° 
 F. Its tinctorial power is very great, one part of the acid, 
 according to Carey Lea, communicating a distinctly yellow 
 colour to 30,000 of water. It is readily soluble in alcohol 
 and ether; strong nitric acid also dissolves it, and the 
 solution is not altered by boiling. Picric acid yields com- 
 pounds with the metals, many of which explode with 
 fearful violence when fired with a detonator. Sodium 
 picrate is sometimes sold as aniline yellow, and serious 
 accidents may arise if due care be not taken. 
 
 Picric acid dyes silk, wool, and other animal substances 
 yellow, the depth of tint varying from a pale straw to a 
 golden colour. It has, however, no affinity for vegetable 
 fibres, such as cotton, flax, and hemp, on which it can only 
 be fixed by the aid of albumen or some similar mordant 
 of animal origin. Wool and silk may be dyed by plunging 
 them into a hot bath of a strength sufficient to give the 
 desired tone, and then washing thoroughly in water. The 
 colour resists the action of light very well, but it is some- 
 
USES OF PICRIC ACID. 455 
 
 what affected by washing, especially if soap be used ; 
 mordanting the goods with alum and tartar tends to render 
 the colour faster. 
 
 PICRIC ACID. 
 
 Picric acid is also used for precipitating aniline green in 
 the process of purification; and in dyeing, to modify the 
 shade of aniline greens, or along with extract of indigo 
 or Prussian blue, for producing greens. 
 
 The affinity which picric acid has for animal fibres 
 renders it useful for detecting cotton when mixed with 
 wool in a fabric. It is merely necessary to plunge the 
 fabric into a hot solution of picric acid, and then wash 
 thoroughly in water; the wool takes a permanent yellow 
 tinge, whilst the fibres of cotton remain unchanged. If 
 the specimen is a dyed one, it is advisable to bleach it 
 before applying the test. Picric acid is frequently mixed 
 with various extraneous substances, such as alum, oxalic 
 acid, borax, and sodium sulphate, the latter arising from 
 unskilful manufacture. These may readily be detected by 
 gently heating the sample with benzene, which dissolves 
 the picric acid and leaves the foreign matters. Its value 
 may also be estimated by making a comparative dyeing 
 experiment with a sample of known purity. 
 
456 DYEING AND CALICO PRINTING. 
 
 By the action of reducing agents on picric acid, a 
 new compound, picramic acid, or amidodinitrophenol, 
 C 6 H 3 (N0 2 ) 2 (NH 2 )0, is produced. It may be regarded 
 as derived from picric acid by the displacement of one of 
 the NO 2 groups by NH 2 thus: — 
 
 C 6 H 3 (N0 2 ) 3 + 6H = C 6 H 3 (N0 2 ) 2 (XH 2 )0 + 2OH 
 
 Picric acid. Picramic acid. 
 
 It may be prepared by passing sulphuretted hydrogen 
 through a solution of picric acid in alcoholic ammonia. 
 The liquid acquires a dark red colour, and, on standing, 
 deposits a mass of deep reddish-brown tables of ammo- 
 nium picramate, from which the acid may readily be 
 obtained by dissolving it in hot water, and precipitating 
 with a slight excess of acetic acid. Aqueous ammonia 
 cannot be substituted for the alcoholic solution in this 
 method of preparation, as in that case the reduction goes 
 farther, and diamidonitrophcnol, C 6 H 3 (N0 2 )(NH 2 ) 2 0, is 
 formed. Picramic acid may also be obtained by the action 
 of other reducing agents on picric acid, as when an alkaline 
 solution is heated with grape sugar, or by dissolving 1 part 
 of picric acid and 7 of ferrous sulphate (green vitriol) in 
 boiling water, and then adding a boiling solution of barium 
 hydrate in slight excess. 
 
 Picramic acid crystallises from its aqueous solution in 
 red needles, and from an ethereal one in garnet-coloured 
 prisms. It melts at 329 F., and decomposes at a higher 
 temperature. It is almost insoluble in water, but soluble 
 in alcohol and ether. It not only combines readily with 
 bases to form salts, but it also unites with acids; the latter 
 compounds, however, are not very stable. 
 
 Both picramic acid and its salts readily dye silk and 
 wool, but they have not come into general use. 
 
 Isopurpuric acid, or picrocyamic acid. Hlasiwetz's method 
 of preparing the potassium compound of this acid consists 
 in pouring a solution of 1 part of picric acid in 9 parts of 
 
ISOPURPURIC ACID. 457 
 
 boiling water, into a solution of 2 parts of potassium 
 cyanide in 4 parts of water at 140° F., with constant stirring. 
 A powerful odour of ammonia and hydrocyanic acid is 
 produced, whilst the solution acquires a deep reddish-brown 
 colour, and, on cooling, forms a crystalline pulp of potas- 
 sium isopurpurate. According to Kopp, a better process 
 is to intimately mix powdered picric acid with twice its 
 weight of potassium cyanide and a little water. After 
 allowing it to stand for half an hour more water is added ; 
 the whole is then heated to no° F., and allowed to cool. 
 
 The crystals obtained by either of these methods, after 
 being drained and pressed, are purified by dissolving them 
 in boiling water, filtering, and allowing the solution to cool. 
 It then deposits isopurpurate of potassium, C 8 H 4 KN0 5 , in 
 brownish-red crystalline scales, with a metallic-green reflex, 
 very similar to murexide. The potassium salt is only 
 sparingly soluble in cold, but more readily in hot water. 
 It is but very slightly soluble in a strong solution of potas- 
 sium carbonate; and this circumstance may be taken 
 advantage of to precipitate it from its solution if, owing to 
 the presence of impurities, it does not crystallise out. 
 The ammonium salt C 8 H 4 (NH 4 )N0 5 . forms dark green 
 crystals, with a metallic lustre, which, like the potassium 
 salt, are but slightly soluble in cold water. This compound 
 is isomeric with murexide or purpurate of ammonium, with 
 which it was for some time supposed to be identical. 
 Murexide, and the other purpurates however, are not explo- 
 sive, whilst ammonium purpurate, when heated on platinum 
 foil, deflagrates like gunpowder, and the corresponding 
 potassium compound detonates sharply. Moreover, on 
 adding hydrochloric acid to a somewhat concentrated 
 solution of murexide, it becomes colourless; and on allow- 
 ing it to stand, a substance called dialuramide crystallises 
 out. A solution of an isopurpurate treated in a similar 
 manner, becomes yellowish-brown, and turbid; and on 
 
45 8 D YEING AND CALICO PRINTING. 
 
 standing, brown amorphous flocks separate. The products 
 of the decomposition of the isopurpurates are colouring 
 matters, dyeing silk of a shade similar to the aniline 
 browns known as Vesuvian and Bismarck. 
 
 Isopurpurate of ammonia has been manufactured by- 
 Messrs* Roberts and Dale, of Manchester, and gives with 
 silk, wool, and leather, beautiful shades of reddish-purple; 
 its employment, however, is but limited. As the isopurpu- 
 rates, when dry, explode readily, and with fearful violence, 
 they should be made into a paste with water and glycerin, 
 which keeps them moist. 
 
 The mordants used in dyeing with the isopurpurates are 
 the same as those employed with murexide, the best being 
 mercury and lead salts. Murexide gives, with mercury, a 
 splendid purple with a violet shade; whilst with isopurpu- 
 rates the purple has a reddish hue: the colours produced by 
 the latter are much faster than those obtained with mu- 
 rexide, being acted on neither by sunlight nor by sulphu- 
 rous acid. Silk mordanted with zinc gives a fine yellow 
 with murexide, and a dark reddish-brown with the isopur- 
 purate. Murexide colours are completely destroyed by 
 acids and by alkalis, whilst those of the isopurpurates 
 merely assume a yellowish tint. In dyeing, isopurpurate 
 of aniline gives good results : this is made by dissolving in 
 the bath 42 parts of aniline hydrochloride for every 100 of 
 potassium isopurpurate. In this bath, silk mordanted with 
 alum acquires a deep garnet-brown ; and wool, which has 
 been mordanted by boiling for two hours with 4 parts of 
 alum and 1 of cream of tartar, becomes chesnut-brown. 
 
 ROSOLIC ACID. — This name was first given by Runge to 
 a red colouring matter which he obtained from coal-tar. 
 On agitating coal-tar naptha with milk of lime, and then 
 adding an acid to the clear aqueous liquor, a mixture of 
 impure phenols with rosolic and brunolic acids is obtained. 
 This mixture is distilled in a current of steam as long as 
 
CORALLIN. 459 
 
 any phenol comes over, and the non-volatile, brown, pitchy 
 matter is dissolved in alcohol: to this solution milk of lime 
 is added, which precipitates calcium brunolate, whilst cal- 
 cium rosolate remains in the rose-coloured solution. On 
 distilling off the alcohol and putting the residue aside, rose- 
 coloured crystals of the lime salt are deposited, and from this, 
 after purification, the rosolic acid may be obtained by pre- 
 cipitating the aqueous solution with acetic acid. 
 
 As it seemed probable that rosolic acid was produced by 
 the oxidation of phenol or cresol, or a mixture of the two, 
 Dr. Angus Smith proposed to prepare it by heating to a 
 high temperature, a mixture of 2 parts of commercial 
 phenol, with I of caustic potash, and 5 of black oxide of 
 manganese. The product is then extracted- with water 
 and the rosolic acid precipitated by hydrochloric acid. 
 
 Tschelnitz mixes heavy coal-tar naphtha with slaked 
 lime, and exposes it to the air for several months. The 
 red mass thus obtained, is then treated in a manner similar 
 to that originally employed by Runge. 
 
 The name rosolic acid, however, has also been applied 
 to various other substances of totally different composition 
 and properties, especially to the product now called 
 Corallin, obtained by heating phenol with a mixture of 
 sulphuric and oxalic acids, and also to that produced by the 
 action of nitrous acid on rosaniline, and which Fresenius 
 has proposed to name pseudocoralli?i. 
 
 Corallin. — In order to prepare this colour, which was dis- 
 covered by Kolbe and Schmitt,* 2 parts of oxalic acid, 
 3 of pure phenol, and 4 of sulphuric acid are heated 
 together at 285 to 300 F. for five or six hours, in a vessel 
 furnished with a cohobator. The dark brown-red mass 
 thus obtained is poured into hot water, when a resinous 
 substance separates having a cantharides-green lustre, whilst 
 the supernatant liquid is a yellowish-red. The mixture is 
 
 * Ann. Chem. Pharm., cxix., 169. 
 
460 DYEING AND CALICO PRINTING. 
 
 then boiled until the odour of phenol, which the vapour 
 has at first, ceases to be perceptible, and, on cooling, the 
 liquor deposits a quantity of orange-red flocks, which 
 together with the insoluble portion are collected and washed. 
 
 In order to obtain corallin in the crystalline state,* 
 it is rubbed up with magnesia, and the mass exhausted 
 by repeatedly boiling it with water. To the filtrate, 
 ammonium chloride is added, when a small quantity 
 of ammonia is given off, and a brilliant crimson precipitate 
 is produced. This is treated three or four times succes- 
 sively with magnesia and precipitated with chloride of 
 ammonium, so as to render the magnesian compound pure. 
 If this is now decomposed by hydrochloric acid, and the 
 precipitate dissolved in boiling alcohol, the pure corallin 
 separates on cooling in long, slender, lustrous, scarlet 
 needles. It crystallises from glacial acetic acid in trans- 
 parent, dark red, rhombic prisms. Its melting point is 
 3 1 3° F. It is only slightly soluble in cold water, but more 
 readily when it is boiling, giving a yellow solution. If an 
 alkali, or an alkaline earth, or one of their carbonates be 
 added, water takes up more of the substance and acquires 
 a beautiful purple-red colour. The addition of potassium 
 ferricyanide to the alkaline solution renders it much darker 
 if the corallin be impure, but does not change it if pure. 
 It dissolves readily in alcohol, ether, and in acetic acid with 
 deep yellow colour. It is also soluble in phenol. 
 
 According to Fresenius, this compound has the formula 
 C 40 H 38 O n , but as it is undoubtedly produced by the action 
 of nascent carbonic oxide on phenol, Kolbe suggests that 
 it may be formylated phenol C 7 H 6 0, or C 6 H 4 (COH)OH, 
 which agrees with the results of the analysis nearly as well 
 as the formula proposed by Fresenius. If Kolbe's view is 
 correct, its formation would be represented by the equa- 
 tion : — 
 
 * Fresenius, Jour. Prakt. Chem., v., 184. 
 
CORALLIN. 461 
 
 C 6 H 5 .OH + CO = C 6 H 4 (COH)OH. 
 
 Phenol. Carbonic Corallin. 
 
 oxide. 
 
 Persoz uses less sulphuric than Kolbe and Schmitt, the 
 proportions being 2 parts of oxalic acid, 3 of phenol, and 
 2 of sulphuric acid, which are heated for several hours. 
 The mass effervesces, becomes thick, and acquires a deep 
 red colour: the reaction may be considered as terminated 
 when a drop of the mixture dissolves in dilute aqueous 
 ammonia with a deep red colour. It is then poured into 
 water and treated in the manner above described. 
 
 Sulphuric acid is not essential to the production of this 
 colour; it merely acts as a dehydrant, and may be 
 replaced, although not with advantage, by boric, arsenious, 
 or arsenic acids. In fact, Prud'homme found that rosolic 
 acid was produced in small quantity if dry phenol were 
 heated with carefully dried oxalic acid. 
 
 AURIN. 
 
 Corallin gives a variety of fine red shades, which are 
 easily modified by the use of proper reagents, but its 
 liability to change renders it somewhat difficult to fix the 
 colour on the fabrics to which it is applied. It may, 
 however, be printed with albumen or lactarine: 8 ozs. of 
 
462 
 
 DYEING AND CALICO PRINTING. 
 
 aurin solution added to 2 lbs. of lactarine dissolved in a 
 mixture of 7 pints of water at 8o° F. with 1 pint of 
 ammonia, gives good results. After printing, the pieces 
 should be steamed 20 minutes. The calcium and lime 
 lakes of corallin are now largely employed by paper 
 stainers. 
 
 
 YELLOW CORALLIN" ON" CALICO. 
 
 Peonine. — This colour, also called red corallin, is ob- 
 tained from corallin by treating it with ammonia at a 
 high temperature according to the method discovered by 
 M. J. Persoz in 1859, and which was patented in France 
 by Messrs. Guinon, Manias, and Bonnet. In their process, 
 9 parts of crude corallin are introduced into a strong iron 
 digestor together with 22 parts of a concentrated solution 
 of ammonia, and heated to 270° F. for three hours. On 
 allowing the vessel to cool, and opening it, the corallin 
 will be found to be completely dissolved in the ammonia, 
 forming a thick liquid with a golden-crimson reflection. 
 On adding an acid to this solution, a deep red precipitate 
 of the colouring matter is obtained, which is capable of 
 dyeing silk and wool of a red colour. Peonine is almost 
 insoluble in water, but very soluble in alcohol, to which it 
 
PEONINE OR RED CORALLIN. 463 
 
 communicates a red colour. Its alkaline solutions acquire 
 a brown colour on exposure to the air. 
 
 The chemical nature of peonine is at present unknown, 
 and from the very different results obtained in dyeing with 
 the two substances it would seem to be different from 
 corallin. Its method of preparation renders it probable 
 that it is an amide or imide of corallin. 
 
 Red corallin is much used for dyeing wool, but it has 
 the disadvantage that when it comes in contact with acids 
 the red colour fades to yellow; this may be prevented, 
 however, by the use of calcined magnesia, the corallin 
 being dissolved in water or alcohol. The colour produced 
 is a rich Turkey red, which maintains its intensity and 
 brilliancy for years. This red shade can be produced at 
 about two-thirds the cost of that from cochineal, and has 
 the advantage that it is not turned blue by washing in 
 water containing much calcium carbonate. The following 
 is a good recipe for printing: — 320 grammes of corallin 
 are dissolved in 1 litre of water and 250 grammes of 
 glycerin, and added to 560 grammes of magnesia sus- 
 pended in 1 litre of water. This mixture is thickened 
 with 3 litres of gum water containing 1500 grammes of 
 gum, then printed, steamed, and washed in the usual Avay. 
 For printing an orange-red with corallin, a lake is formed, 
 by dissolving 2000 grammes of corallin in a solution of 
 soda at io° B., diluting it with water, and after adding 
 protochloride of tin, heating the mixture. The precipitate 
 is mixed with: — 
 
 Magnesia 100 grammes 
 
 Oxalic acid 260 „ 
 
 Gum 2000 „ 
 
 Water 10 litres 
 
 A bath for dyeing with corallin may also be prepared 
 by dissolving the dye in alcohol with the help of a little 
 soda, then pouring it into a large quantity of lukewarm 
 
464 DYEING AND CALICO PRINTING. 
 
 water, and nearly neutralising it with tartaric acid. The 
 goods are then entered, and worked for an hour and a 
 half. Cotton must be mordanted with tin, and sumach or 
 galls. The colour, which is a shade between cochineal 
 and magenta, resists washing, but is affected by soap or 
 exposure to sunlight. 
 
 CORALLIN ON WOOL. 
 
 Azulin. — This blue colour was discovered by Marnas, 
 and patented by Messrs. Guinon, Marnas, and Bonnet. It 
 is obtained by the mutual reaction of aniline and peonine. 
 For this purpose, a mixture of 5 parts of peonine with 8 of 
 aniline, are heated to the boiling point for several hours. 
 The whole is thus transformed into a blue colouring matter, 
 which is purified by washing it, first with dilute hydrochloric 
 acid, then with hot coal-tar naphtha, and finally with a dilute 
 solution of caustic soda. It is a violet powder with a 
 golden iridescence, which is insoluble in water, but soluble 
 in alcohol. According to Willm it has the composition 
 QoHjoNCK, and may be regarded as dioxyphenylamide 
 NH 2 (C 6 H 5 0) 2 . 
 
 A blue similar to, or identical with this, is also produced 
 by treating aurin with aniline.* When aurin is boiled with 
 
 *Jour. Chem. Soc, xxvi., 444. 
 
PSE UDOCORALLIN. 465 
 
 aniline and a little acetic acid, the solution soon assumes a 
 pure blue colour, and on removing the excess of aniline by- 
 means of boiling dilute hydrochloric acid, a resinous sub- 
 stance is obtained consisting of a mixture of different bodies, 
 some of which are soluble in acetic acid and in alcohol, and 
 some insoluble. On heating the mixture of aniline and aurin 
 for twenty hours to 21 2° R, a blue solution is obtained, 
 which is also a mixture. A portion of the product dissolves 
 in caustic soda with a purple colour, and is precipitated by- 
 acids in blue flocks, soluble in alcohol, and in acetic acid. 
 The portion insoluble in alkalis dissolves completely in 
 alcohol and acetic acid, with a fine blue colour; it is, however, 
 only partly soluble in ether, the portion remaining undissol- 
 ved being a dark blue powder with a golden reflection. 
 
 Pseudocorallin. — This is the name which Fresenius pro- 
 poses to give to the compounds discovered by Caro and 
 Wanklyn, and which they considered to be rosolic acid. 
 It may be prepared by dissolving rosaniline or magenta in 
 excess of hydrochloric acid, in such proportion that there 
 may be three molecules of the acid to one of base, and then 
 adding finely powdered potassium nitrite until the odour 
 of nitrous acid no longer disappears on agitation. This 
 converts the rosaniline into an azocompound, which, when 
 boiled with dilute hydrochloric acid, decomposes with 
 effervescence due to the escape of nitrogen, whilst red 
 flocks separate; these, however, soon melt together and 
 form a brown resinous cake, with a golden lustre. If per- 
 fectly pure rosaniline be used in this operation, the boiling 
 mother liquor, poured off from the resinous cake, deposits a 
 small portion of the pseudocorallin in well formed crystals, 
 which after recrystallisation from alcohol closely resemble 
 corallin in appearance. Caro and Wanklyn, who did not 
 succeed in obtaining this compound in the crystalline state, 
 assigned to it the formula C 20 H 16 O 3 , and supposed it to be 
 formed by the following reactions : — 
 FF 
 
466 DYEING AND CALICO PRINTING. 
 
 C 20 H p N 3 + 3HNO, = C 20 H 10 N 6 + 60H 2 . 
 
 Rosaniline. Azorosaniline. 
 
 C 20 H 10 N 6 + 3 OH 2 = C 20 H 16 O 3 + 3 N 2 . 
 
 Azorosaniline. Rosolic acid. 
 
 Fresenius, however, who has examined the pure crystalline 
 compound, finds that it melts at 316 F., and on analysis 
 gives numbers corresponding with the formula C 2C H 28 O 10 . 
 It will be seen from this that Caro and Wanklyn's sub- 
 stance, pseudocorallin, is not identical with that obtained 
 by Kolbe and Schmitt (corallin) by the action of sulphuric 
 acid on a mixture of oxalic acid and phenol ; moreover, an 
 alcoholic solution of corallin is decolorised on the addition 
 of a concentrated solution of acid sodium sulphite, whilst 
 pseudocorallin undergoes no change. 
 
 Aurin. — There is a compound known in commerce 
 by the name of yellow corallin, or aurin, and which is 
 obtained by heating a mixture of phenol with oxalic and 
 sulphuric acids in a manner similar to that employed in 
 preparing corallin, but the temperature employed is lower. 
 This colouring matter has been examined by Dale and 
 Schorlemmer, who find that the commercial product is a 
 mixture, from which they succeeded in extracting aurin by 
 dissolving it in alcohol, and saturating the liquid with 
 ammonia. A compound of ammonia and aurin is thus 
 formed, which, being comparatively insoluble in alcohol, 
 separates in the crystalline state. After being collected 
 and washed with alcohol, it is treated with an acid, which 
 removes the ammonia, and liberates the aurin. Aurin 
 crystallises in slender red needles from concentrated hydro- 
 chloric acid, and from a mixture of alcohol and acetic acid, 
 in dark red trimetric crystals; both these, however, obsti- 
 nately retain a small quantity of water and acid. Aurin, 
 C 20 H u O 3 , when pure, does not melt even at 422 F.; 
 whilst corallin fuses at 3 1 3 F. ; moreover, the crystalline 
 forms of the two substances are quite distinct. 
 
 Instead of extracting aurin from the commercial article, 
 
A URIN AND LE UK A URIN 467 
 
 which is always made with an impure phenol containing 
 cresol, it may be obtained in the pure state at once by heat- 
 ing to 230 F., for five or six days, a mixture of oxalic acid 
 and pure crystallised phenol, pouring the product into water, 
 distilling off the excess of phenol in a current of steam, 
 and then dissolving the aurin in dilute caustic soda, and 
 precipitating it with hydrochloric acid. The crystals only 
 require to be dissolved in boiling alcohol and allowed to 
 cool, when the pure substance separates in distinct needles. 
 The difference which undoubtedly exists between aurin 
 and the corallin of Kolbe and Schmitt must be looked for 
 in the difference of temperature at which the two sub- 
 stances are produced, namely, below 230 F. for aurin, and 
 from 285 to 300 F. for corallin. The reaction which takes 
 place in the formation of aurin may be represented by the 
 following equation : — 
 
 3 C 6 H 6 + 2CO = C 20 H u O 3 + 2 OH 2 
 Phenol. Aurin. 
 
 Aurin forms crystalline compounds with sulphurous 
 anhydride, and with the acid sulphites of alkalis. When 
 an alkaline solution of aurin is heated with zinc dust, it 
 becomes colourless, and the addition of an excess of hydro- 
 chloric acid then causes the precipitation of a new sub- 
 stance, leukanrin, C 20 H 16 O 3 . When pure, it crystallises in 
 thick, hard, colourless prisms, which are freely soluble in 
 acetic acid. 
 
 Aurin, or yellow corallin, yields very fine orange shades 
 on wool by printing with a lake prepared by dissolving 
 5 lbs. of yellow corallin in 2 gallons of caustic soda at 
 10° B., heated to a temperature of 140 F.; it is then 
 diluted with 20 gallons of water, again heated until 
 entirely dissolved, and rather more than 1^ pints of 
 bichloride of tin at 55 B. added, previously diluted with 
 1 gallon of water. The precipitate is then collected, and 
 allowed to drain. It should measure 4 gallons. 
 
468 DYEING AND CALICO PRINTING. 
 
 Corallin paste 2 gallons 
 
 Powdered gum 4 lbs. 
 
 Oxalic acid 11 ounces 
 
 The mixture is heated until the gum and oxalic acid are com- 
 pletely dissolved, when it is ready for printing. 
 
 An orange-red shade may be obtained by dissolving the 
 aurin in dilute ammonia so as to make a solution of 
 32 Tw. This solution is then mixed with 4 parts of 
 starch paste, containing 14 lbs. to the gallon, printed, 
 dried, and steamed for one hour. 
 
 Phenicienne, or Rothine. — This colour, which is also 
 prepared from commercial carbolic acid, was discovered 
 by Roth in 1863. It is made by gradually adding to 
 carbolic acid a mixture of nitric acid of density 1 '35 with 
 twice its volume of sulphuric acid. The reaction is very 
 violent at first, so that only a very small portion of the 
 acid must be added at a time, but larger quantities may 
 be poured in afterwards in successive portions until red 
 nitrous fumes cease to be given off; for this purpose 
 about 10 to 12 parts of the mixed acids are required for 
 1 of carbolic acid. As soon as the reaction is complete, 
 the product is poured into a large quantity of water, and 
 the brown precipitate which is produced is thoroughly 
 washed with water, which is a tedious process, occupying 
 several days. The colour is very soluble in alcohol, ether, 
 and acetic acid, also in alkaline solutions, but almost 
 insoluble in water. It dyes silk and wool without a 
 mordant, but cotton must be mordanted with tannin and 
 stannate of soda. It cannot be employed in printing, as 
 the process of steaming destroys the brilliancy of the 
 colour. It yields shades varying from a deep garnet to a 
 chamois, according to the strength of the solution, or the 
 nature of the oxidising agents employed. 
 
 Fols yellow. — This colour is obtained by heating in an 
 open cast-iron pot for twelve hours, at 21 2° F., a mixture 
 
CRESOL YELLOWS. 469 
 
 of 5 parts of carbolic acid with 3 of arsenic acid in fine 
 powder. In about two hours the reaction commences, 
 and the mass acquires a yellow colour, which gradually 
 increases in intensity. At the end of the twelve hours 
 the temperature is raised to 260° F., at which it is 
 maintained for six hours more. When cool, 10 parts of 
 acetic acid at 7 B. are added; the product is dissolved 
 in a large quantity of water, filtered, and the colouring 
 matter precipitated by the addition of common salt. It 
 may be purified by converting it into the barium salt and 
 decomposing the latter with dilute sulphuric acid. When 
 pure it forms reddish-brown scales or plates, which are 
 readily soluble in water, alcohol, and ether. It dyes wool 
 and silk yellow, and in presence of caustic or carbonated 
 lime or baryta gives red shades, which are not affected 
 by soap. 
 
 There is another yellow colour, known in commerce as 
 'Campo Bello yellow,' which is prepared from carbolic acid, 
 by a secret process in the possession of Messrs. Schraeder 
 and Berend, of Schonfeld, Leipzig. It is soluble in water, 
 and dyes wool various shades of yellow: it is usual to add 
 alum to the bath in the proportion of 3 lbs. to every 50 lbs. 
 of wool. 
 
 CRESOL COLOURS. — Two yellow colours occur in com- 
 merce, known under the names of 'gold yellow' and 
 'Victoria yellow.' They are both impure salts of dinitro- 
 cresols. The former, 'goldgelb 1 or 'gold yellow,' is 'a brown 
 crystalline mass, which detonates sharply when heated ; it 
 is the potassium compound of a dinitrocresol, C 6 H 2 (N0 2 ) 2 
 CH3.OH, which when pure melts at 180 F. The free 
 dinitrocresol may be obtained by strongly acidulating an 
 aqueous solution of the yellow dye with sulphuric acid and 
 then agitating it with ether, which takes up the liberated 
 dinitrocresol and deposits it again in the crystalline state 
 on evaporation. It crystallises readily from boiling water, 
 
470 DYEING AND CALICO PRINTING. 
 
 and is also readily soluble in alcohol, ether, benzene, and 
 chloroform. The potassium compound is only slightly 
 soluble in cold water. 
 
 'Victoria yellow' is also a salt of a dinitrocresol, which 
 may be obtained from the dye in a similar manner to that 
 just described. The nitrocompound, however, is not iden- 
 tical, but only isomeric with that from 'goldgelb,' as it 
 melts at a much higher temperature, 230 F. Neither of 
 these colours is extensively used. 
 
 Naphthalene Colours. — One of the most abundant 
 of the compounds occurring in coal-tar is the hydrocarbon 
 naphthalene, C 10 H 8 , so much so, that the heavier portions of 
 the coal-oil, when subjected to a low temperature, become 
 quite pasty from the large quantity of naphthalene de- 
 posited by them in the crystalline state. The gas mains 
 also, especially in the immediate neighbourhood of the gas 
 works, frequently become choked up by the crystals of 
 naphthalene which form in them, and which are occasion- 
 ally met with in large masses of dazzling whiteness. As 
 this substance occurs in such abundance, many chemists 
 have endeavoured to turn this waste product to account, by 
 transforming it into colouring matters similar to those ob- 
 tained from aniline. Unfortunately, however, most of the 
 naphthalene colours want that brilliancy and purity of tone 
 which is such a distinguishing characteristic of those 
 derived from aniline. 
 
 Naphthalene. — This hydrocarbon volatilises very readily, 
 so that it sublimes in colourless crystals on gently heating 
 the mass obtained by draining and pressing the pasty naph- 
 thalene deposited from the heavy coal-oils when they are 
 cooled. These, however, have a disagreeable odour, which 
 according to Ballo is due to the presence of leucoline oil: 
 this may be removed by heating the crystals with sulphuric 
 acid, and then washing and resubliming the fused cake of 
 naphthalene. When perfectly pure, naphthalene has a faint 
 
DINITR ONAPHTHOL. 47 1 
 
 but not unpleasant odour, melts at I74°.5 F. and boils at 
 42 3 F. It is readily soluble in alcohol, ether, and benzene, 
 but insoluble in water. Although it has such a high boil- 
 ing point, it passes over readily with the vapour of water, 
 or when distilled in a current of steam. 
 
 DinitronapJithol. — Naphthalene readily dissolves in con- 
 centrated sulphuric acid when the two are heated together; 
 the product consisting of a mixture of two isomeric sulpho- 
 napJithalic or naphthalene sulphonic acids y C 10 H 7 .SO 3 H, in 
 varying proportion. If the temperature be higher than 
 320 F., scarcely anything but /3-naphthalene sulphonic acid 
 will be formed, whilst at 175 F. the product is principally 
 the a modification. If the potassium or sodium compound 
 of either of these acids is fused with excess of caustic soda, 
 the SO3H group is replaced by OH, and a corresponding 
 naphthol is formed, thus — 
 
 C 10 H 7 .SO 3 Na + NaHO = C 10 H 7 .OH + Na 2 S0 3 
 
 Sodium sulpho- Sodium Naphthol. Sodium 
 
 naphthalate. hydrate. sulphite. 
 
 On dissolving the product in water, and adding an excess 
 of acid, the naphthol is precipitated as an oil which 
 solidifies on cooling. 
 
 a-naphthol crystallises in small shining, colourless 
 needles, which are easily soluble in alcohol or ether, 
 and in alkaline solutions, but only slightly soluble 
 even in boiling water. It melts at about 203 F. 
 a-Dinitronaphthol, C 10 H s ,(NO 2 ) 2 .OH cannot be procured 
 by the direct action of nitric acid on naphthol, but if the 
 naphthol be dissolved in concentrated sulphuric acid, 
 whereby it is converted into naphthol-sulphonic acid, then 
 diluted with water, nitric acid added to the solution, and 
 the whole gently heated, it deposits the dinitronaphthol in 
 the form of minute yellow needles. This process was 
 patented by Wichelhaus and Darmstaedter in 1867. 
 
 The same compound is formed by treating naphthylamine, 
 
472 DYEING AND CALICO PRINTING. 
 
 first with nitrous acid, and then with nitric acid, a method 
 previously patented by Martius. He adds a slight excess 
 of potassium nitrite to an acid solution of naphthylamine, 
 whereby diazonaphthalene hydrochloride is produced — 
 C 10 H 9 N.HC1 + HN0 2 = C 10 H 6 N 2 .HC1 + 2OH, 
 
 Naphthylamine Nitrous Azonapthalene 
 
 hydrochloride. acid. hydrochloride. 
 
 If this compound were boiled with hydrochloric acid, 
 a-naphthol would be produced, but if nitric acid is sub- 
 stituted for hydrochloric acid, the naphthol at the moment 
 of its formation is converted into dinitronaphthol thus — 
 C 10 H 6 N 2 .HC1 + 2NO..OH = C 10 H G (NO,)X) + N 2 + HC1 + OH 2 
 
 Diazonaphthalene Nitric Dinitronaphthol. 
 
 hydrochloride. acid. 
 
 The a-dinitronaphthol crystallises out in yellow needles 
 which, if required quite pure, may be converted into the 
 ammonium salt, and then after repeated crystallisation 
 again decomposed by an acid. According to Ballo, it may 
 also be prepared by heating 1 part of naphthylamine with 
 5 parts of nitric acid of density 1*35, and when all action 
 has ceased, diluting the mixture with water and boiling. 
 This nitro-compound forms beautiful crystalline com- 
 pounds with the alkalis and alkaline earths. The lime 
 salt is manufactured on a large scale by Messrs. Roberts 
 and Dale, of Manchester, and is known as 'Manchester 
 yellow' or 'Martius' yellow.' Its tinctorial power is even 
 greater than that of picric acid, and it gives a very pure 
 gold colour on silk and wool without the slightest tinge 
 of green, which is so objectionable with picric acid. It 
 also possesses the advantage over the latter that it is not 
 volatile, so that it will bear steaming, and does not come 
 off on other goods with which it may come in contact. 
 
 $-naplithol. — This compound closely resembles a-naphthol, 
 and is formed, as has been already noticed, by fusing 
 potassium |3-naphthalene-sulphonate with excess of caustic 
 soda. It likewise yields a nitro derivative, but it is difficult 
 
INDOPHANE. 473 
 
 to prepare, so that, although it dyes silk and wool a deep 
 yellow, it has not come into use. 
 
 Naphthylpurpuric acid. — The naphthylpurpurates are 
 prepared in a manner somewhat analogous to that 
 employed for the isopurpurates, but the reaction should 
 take place in an alcoholic solution. Dinitronaphthol is dis- 
 solved in 40 times its weight of boiling alcohol in a flask 
 furnished with an inverted condenser, and a concentrated 
 aqueous solution of potassium cyanide mixed with alcohol 
 is gradually added. The orange-coloured potassium com- 
 pound of binitronaphthol, which is at first formed, soon 
 dissolves, and the boiling liquid acquires a deep brown 
 hue. The solution is now concentrated by distillation, and 
 the potassium naphthylpurpurate, C u H 6 KN 3 4 , which 
 separates on cooling, is purified by pressure and recrystallisa- 
 tion from water. It forms brown, microscopic plates, which 
 are very soluble in water, and have a slight green 
 iridescence. The free acid has not been obtained. 
 
 Indophane. — This compound is also produced by the 
 action of potassium cyanide on dinitronaphthol: for this 
 purpose 6 parts of the nitro compound are dissolved in 
 400 of boiling water by the aid of ammonia, and to this, 
 a hot concentrated solution of 9 parts of potassium 
 cyanide is gradually added. As soon as the precipitation 
 is complete, the product is thoroughly washed with boiling 
 water, and the violet-coloured mixture of free indophane 
 and potassium indophane is boiled with very dilute 
 hydrochloric acid to remove the potassium, washed until 
 free from acid, and dried. 
 
 Pure indophane, C 22 H 10 N 4 O 4 , has a violet colour and a 
 brilliant green iridescence. It is insoluble in water or 
 alcohol, but moderately soluble in concentrated sulphuric 
 acid, yielding a purple-red liquid. 
 
 Resorcin-indophane, a substance analogous to that just 
 described, is formed when trinitroresorcin (styphnic acid) 
 
474 DYEING AND CALICO PRINTING. 
 
 is treated with potassium cyanide. Schreder* prepares it 
 by gradually adding I part of potassium cyanide dissolved 
 in 5 of water at I io° F. to a solution of 5 parts of potas- 
 sium styphnate in 50 of water at 170 F., maintaining the 
 mixture at that temperature for ten or fifteen minutes ; the 
 liquid is then quickly filtered through linen, and the 
 potassium compound of resorcin-indophane, which separ- 
 ates, collected, and washed with cold water until the wash 
 water begins to have a green colour. On adding dilute 
 sulphuric acid to a warm concentrated solution of this 
 salt, and allowing it to cool, impure resorcin-indophane 
 crystallises out in slender needles. It may be purified by 
 dissolving the pressed crystals in hot water, filtering, and 
 adding strong hydrochloric acid to the clear solution. 
 
 Resorcin-indophane, C 9 H 4 N 4 6 , forms small needles 
 with a bronze iridescence, insoluble in alcohol, but very 
 soluble in water, yielding a solution of a pure blue-violet 
 colour; it is also soluble in cold concentrated sulphuric 
 acid, but is precipitated again unaltered on the addition of 
 water. Potassium resorcin-indophane C c H 2 K 2 N 4 6 + 
 OH, crystallises in microscopic needles, which dissolve 
 with difficulty in cold, but readily in boiling water, with a 
 pure green colour similar to that of potassium manganate. 
 The concentrated aqueous solution gelatinises on cooling, 
 but if potash be added, the salt separates in the crystalline 
 state. It is insoluble in alcohol, and when strongly heated 
 decomposes with explosion. 
 
 Chloroxynaphthalic acid, or chloroxynaphthaquinone. — 
 When naphthalene is treated with potassium chlorate and 
 hydrochloric acid it is converted into a mixture of 
 monochloronaphthalene and dichloronaphthalene, and this 
 product, if boiled with nitric acid, yields phthalic acid 
 and chloroxynaphthyl chloride. When the latter com- 
 pound is boiled with a dilute alkaline solution, it is 
 
 *Ann. Chem. Pharm., clxiii., 297, 
 
NAPHTHYLAMINE. 475 
 
 decomposed, yielding a salt of chloroxynaphthalic acid, 
 C 10 H 5 ClO 3 , from which the free acid may be obtained by 
 precipitation with hydrochloric acid. The pure acid is a 
 pale yellow crystalline powder, which forms beautiful 
 compounds with barium, zinc, and copper. It dyes wool 
 of a scarlet colour without the aid of a mordant. Some 
 of the salts of this acid are beautiful pigments. The 
 preparation of this acid and its salts has been carried out 
 on a large scale by Messrs. P. and E. Depouilly. 
 
 Carminaphtha. — This compound was first obtained by 
 Laurent by acting on naphthalene with a mixture of 
 potassium dichromate and sulphuric acid, but the exact 
 circumstances under which it is formed have not been 
 fully investigated. It is of a carmine-red colour, almost 
 insoluble in water, but readily soluble in alcohol. It is a 
 substantive colour on wool and silk, giving orange-red and 
 red-violet shades. 
 
 NitroxynaptJialic acid. — This compound, also called 
 French yellow and chryseic acid, was discovered by Durant 
 and Gelis. It may be prepared by heating to 300 F., in a 
 current of air, a mixture of 20 parts of nitronaphthalene, 
 50 of slaked lime, and 15 of potassium hydrate dissolved in 
 the smallest possible quantity of water. In ten or twelve 
 hours the mass will have assumed a deep yellow colour, and 
 the reaction may be considered as completed. On ex- 
 tracting the product with water, a reddish-yellow solution 
 is obtained. This, when concentrated, and strongly acid- 
 ulated with hydrochloric acid, deposits the colouring matter 
 as a yellow magma, which should be washed with water 
 and dried. It dissolves easily in acetic acid, alcohol, and 
 hot water, and may be obtained in fine golden-yellow 
 needles, which are not volatile. It dyes silk and wool a 
 full golden-yellow. 
 
 Naphthylamine. — This base, which bears the same relation 
 to naphthalene that aniline does to benzene, is prepared by 
 
476 DYEING AND CALICO PRINTING. 
 
 processes very similar to those employed in manufacturing 
 the latter. 
 
 Naphthylamine, C 10 H 9 N or C 10 H 7 .NH 2 , was discovered 
 by Zinin in 1842, when acting on nitronaphthalene by 
 ammonium sulphide. The nitronaphthalene for this pur- 
 pose was prepared by treating finely divided naphthalene at 
 the ordinary temperature for five or six days with nitric 
 acid of density 1 "35, thoroughly incorporating the mixture 
 from time to time, or more rapidly by heating the two sub- 
 stances together at 2 1 2° F. with constant agitation. The pro- 
 duct is thoroughly washed and then strongly pressed. If 
 required pure it must be crystallised from alcohol. 
 
 In Zinin's process the nitronaphthalene is dissolved in 
 alcoholic ammonia, sulphuretted hydrogen is passed into 
 the solution to saturation, and the whole is allowed to 
 stand: sulphur is then liberated, and the nitronaphthalene 
 is reduced to naphthylamine. 
 
 C 10 H 7 .NO 2 + 3SH 2 - C 10 H 7 .NH, + 2OH, + 3S 
 Nitronaphthalene. Naphthylamine. 
 
 Piria succeeded in obtaining naphthylamine by first con- 
 verting nitronaphthalene into ammonium thionaphthamate 
 by boiling it with dilute alcohol and ammonium sulphite, 
 and then heating the product with dilute sulphuric acid. 
 Naphthylamine sulphate is then formed. 
 2 C 10 H 9 NSO 3 + 20H 2 = (C 10 H 9 N) 2 H 2 SO 4 + H 2 SO, 
 
 Thionaphthamic Naphthylamine sulphate, 
 
 acid. 
 
 Roussin reduces nitronaphthalene by means of tin and 
 hydrochloric acid, but by far the best method is that of 
 Bechamp, by which, in fact, naphthylamine is now 
 universally manufactured. For this purpose, 2 parts of 
 nitronaphthalene are fused in a cast-iron pot heated on a 
 sand bath, and 2 parts of iron turnings are added, and the 
 whole thoroughly mixed. The pot is now taken off the 
 bath, and 2 parts of acetic acid are poured in, when a 
 powerful reaction takes place. As soon as this has 
 
AZODINAPHTHYLDIAMINE. 477 
 
 terminated, and the product is cool, it is mixed with 2 
 parts of quicklime, introduced into a retort, and submitted 
 to distillation, either per se or in a current of steam. Ballo 
 prefers to decompose the product with a solution of caustic 
 soda, and then distil by means of steam. 
 
 Naphthylamine crystallises in white silky needles, which 
 soon acquire a purplish-brown tint on exposure to the air. 
 Its odour, which is most disgusting, is exceedingly persis- 
 tent. It melts at 122 F., and boils above 570 F. It is 
 almost insoluble in water, but is readily soluble in alcohol 
 or ether, and in acid solutions. It is readily sublimable. 
 
 Azodinaphthyldiamine, C 20 H 15 N 3 , is a base which was 
 discovered by Perkin and Church, and is formed by treating 
 naphthylamine hydrochloride with a mixture of potassium 
 hydrate and nitrite, the reaction being: — 
 
 2 (C 10 H 9 N.|HC1) + KHO + KN0 2 - Q H 15 N 3 + 2KCI + 3 OH 2 
 
 Naphthylamine Azodinaphthyl- 
 
 hydrochloride. diamine. 
 
 In preparing the substance, however, regard must be had 
 to the state of concentration of the solutions, and the tem- 
 perature at which the operation is performed ; for if a 
 moderately concentrated solution of the potassium hydrate 
 and nitrite be added to a solution of the naphthylamine 
 hydrochloride, saturated at 63° F., and which contains 35 
 grammes of the salt per litre, the product is mixed with a 
 large amount of resinous matters; whilst, if the solution be 
 too dilute, the potash precipitates unaltered naphthylamine. 
 On this account Lecco* advises that a preliminary trial 
 should be made with small portions of the solutions, and 
 when the precipitate is a brownish-red the solutions may 
 be considered to have the proper degree of concentration 
 for the given temperature. If they are too strong the pre- 
 cipitate will be dark brown. This precipitate is purified by 
 dissolving it in a boiling mixture of alcohol and ether, 
 *Deut. Chem. Ger. Ber., vii., 1290. 
 
478 DYEING AND CALICO PRINTING. 
 
 filtering hot, and adding hot water until the liquid becomes 
 turbid; on cooling, the azonaphthyldiamine is deposited in 
 reddish-brown needles, which have a metallic-green irides- 
 cence. It melts at 347 F. according to Lecco (266° F. 
 Perkin), and is moderately soluble in alcohol, ether, and 
 benzene; insoluble in water. The acid solutions are deep 
 violet, but the original orange-red tint is restored on the 
 addition of an alkali. 
 
 RosanaphtJiylamine. — This colouring matter, which is 
 also known as 'Naphthylamine red' and 'Magdala red,' 
 appears to be produced when naphthylamine is treated 
 with oxidising agents, such as mercuric nitrate or bichloride 
 of tin ; but the quantity formed is far too small to render 
 these processes available for its manufacture. 
 
 The method adopted by Girard is to heat a salt of naph- 
 thylamine with a proper quantity of azodinaphthyldiamine, 
 the proportions taken being : — 
 
 Powdered Azodinaphthyldiamine 6 lbs. 
 
 Naphthylamine 6 „ 
 
 Glacial acetic acid 5 „ 
 
 These materials are heated in a sand bath to a temperature 
 of about 340° F., in a glass flask of the capacity of 2 gallons. 
 The materials gradually dissolve, whilst ammonia is given 
 off, and the mass acquires a red colour. Care must be 
 taken to stop the operation as soon as a violet coloration 
 begins to appear on the sides of the vessel. About 6 ozs. 
 of glacial acetic acid are now added, and after thoroughly 
 mixing, the contents are poured out on cast-iron plates and 
 allowed to cool. To purify the crude product it is dissolved 
 in 50 times its weight of water acidulated with hydro- 
 chloric acid, and carefully filtered through flannel. It is 
 then exactly neutralised with sodium carbonate, and the 
 colour precipitated by the addition of salt, as in the pre- 
 paration of the aniline colours. This precipitate consists 
 of crystals of impure rosanaphthylamine hydrochloride 
 
MAGDALA RED. 479 
 
 which may be rendered sufficiently pure for the purposes 
 of the dyer by two successive solutions in dilute acid, and 
 reprecipitations by salt. The crude product may also be 
 purified by decomposing it with a slight excess of a solution 
 of soda, distilling off the unaltered naphthylamine in a 
 current of steam, dissolving the residual base in hydro- 
 chloric acid, and precipitating with salt in the manner just 
 described. This colour is prepared on a large scale by 
 Scheurer-Kestner, and by Durand and Hugenin, of Basle. 
 
 The base itself, rosanaphthylamine, C 30 H 21 N 3 , has not been 
 obtained in a pure state, but its composition may be infer- 
 red from that of its salts. Its mode of formation is as follows : 
 C 20 H 15 N 3 + C 10 H 9 N = . C 30 H 21 N 3 + NH 3 
 
 Azodinaph- Naphthyl- Rosanaph- 
 
 thyldiamine. amine. thylamine. 
 
 being, precisely analogous to that which takes place in the 
 formation of azodiphenyl blue by the action of aniline on 
 azodiphenyldiamine. Rosanaphthylamine hydrochloride, 
 when pure, forms large needles, with a green metallic reflex. 
 They are only slightly soluble in cold water, more so in 
 boiling water, and readily in hot alcohol. The free base, 
 when treated with the iodides of methyl and ethyl, yields 
 splendidly crystallised colouring matters. 
 
 By heating mixtures of azodinaphthyldiamine with 
 aniline or with toluidine, Lecco has succeeded in obtaining 
 new colouring matters very similar to 'Magdala red.' 
 
 NaphtJiylamine violet. — This colour is produced in a 
 manner very similar to aniline black, but unlike the latter, 
 it does not appear to be the final result of the oxidising 
 process, but only an intermediate stage. 
 
 Kielmayer prints the following mixture: 
 
 Starch 456 grammes. 
 
 Water 2500 ,, 
 
 Naphthylamine 118 „ 
 
 Hydrochloric acid (specific gravity 1 •12) 79 „ 
 The naphthylamine is dissolved in the acid diluted with 
 
480 DYEIXG AXD CALICO PRIXTIXG. 
 
 part of the water (ij4 litres), then added to the starch, 
 which has been boiled with the remainder of the water (i 
 litre), and the whole boiled for a few minutes : when cold, 
 1 3 J < grammes of potassium chlorate dissolved in 300 
 grammes of water are added. The printed goods are aged 
 for three days, then passed through a weak soda bath, and 
 finally through a soap bath. The shade of colour produced 
 is much affected, however, by the temperature of the oxi- 
 dising room, which should be kept low, and the atmosphere 
 should contain vapours of acetic acid. 
 
 Blumer-Zweifel makes a mixture for printing thus : — 
 
 Gum water 1 litre. 
 
 Xaphthylamine 1 5 to 45 grammes. 
 
 Solution of chloride of copper at 5 1 3 B 15 „ 
 
 After printing, the fabric is aged for two or three days 
 at J J" F., and then washed with soap. Fifteen grammes of 
 naphthylamine gives a pale shade, 30 a medium shade, and 
 45 a deep shade. Alkalis render the colours reddish, 
 whilst acids give it a blue tint. 
 
 Ballo has obtained a violet colour similar in every 
 respect to Hofmann's violet, by heating magenta with 
 monobromonaphthalene. The saturated alcoholic solution 
 of the dye is of such a deep violet colour, that it appears 
 almost black, whilst the addition of a small quantity of 
 hydrochloric acid to the liquid, changes the colour to blue. 
 
 There are two other naphthalene colours, oxynaphthalic 
 acid, and naphthazarin or dioxynaphthaquinone,the methods 
 of preparation and properties of which have been already 
 described when treating of alizarin (p. 55.); for it was at one 
 time imagined that oxynaphthalic acid would prove to be 
 identical with alizarin, whilst napthazarin was, for some time 
 after its discovery by Roussin, considered to be alizarin 
 itself. 
 
 O. H. HILL LIBRARY 
 
 North Carolina State College 
 
INSERT FOLDOUT HERE 
 
APPENDIX. 
 
 TABLES 
 
 FOR DISTINGUISHING THE DIFFERENT 
 
 COLOURING MATTERS 
 
 FIXED ON TISSUES BY PRINTING OR 
 DYEING. 
 
 GG 
 
482 
 
 I.— BLUE COLOURING 
 
 Navie of the 
 colouring matter. 
 
 Combustion of the 
 coloured fibre on 
 platinum foil. 
 
 Immersion in dilute 
 hydrochloric acid. 
 
 Immersion in dilute 
 soda solution. 
 
 Vat Indigo. 
 
 Leaves a small 
 quantity of colour- 
 less ash, which 
 sometimes contains 
 lime, and may also 
 contain a little ox- 
 ide of iron. 
 
 No action. 
 
 No action. 
 
 Indigo carmine, 
 alkaline sulphindi- 
 gotates, Saxony 
 blue. 
 
 Leaves a small 
 quantity of white 
 ash sometimes con- 
 taining tin. 
 
 Loses a little of 
 its colour. 
 
 Loses a little of its 
 colour; the solution, 
 and sometimes the 
 edges of the fabric 
 becoming green. 
 
 Prussian blue. 
 
 Reddish ferrugi- 
 nous ash. 
 
 Is not altered. 
 
 Gradually becomes 
 yellow. Thesolution 
 supersaturated with 
 HC1, becomes blue 
 on the addition of a 
 few drops of per- 
 chloride of iron. 
 
 Logwood blue. 
 
 White residue, 
 rarely greyish. The 
 ash contains alumi- 
 na, and occasion- 
 ally a little oxide 
 of copper. 
 
 Becomes red, as 
 does also the liquid. 
 
 A little deeper in 
 shade ; pure blue. 
 
 Aniline blue. 
 
 Little ash, and no 
 trace of any mor- 
 dant with wool or 
 silk. 
 
 No alteration 
 takes place. 
 
 The dark shades 
 become quickly vio- 
 let, the lighter ones 
 flesh-coloured. 
 
 Ultramarine. 
 
 Blue ashes. 
 
 Is decolorised 
 with disengagement 
 of sulphuretted hy- 
 drogen. 
 
 No alteration. 
 
MATTERS. 
 
 433 
 
 Immersion in 
 
 a solution of 
 
 chloride of 
 
 lime. 
 
 Immersion in 
 a solution of 
 
 permanganate 
 of potash to 
 which a little 
 sulphuric acid 
 has been added. 
 
 Remarks. 
 
 Bleaches 
 slowly. 
 
 Quickly be- 
 comes deco- 
 lorised. 
 
 This colouring matter may be met with on woollen, 
 cotton, flaxen, and hempen fibres, but not upon silk. 
 Nitric acid produces a pale yellow coloration. If the co- 
 loured fibre be placed in a capsule covered with a watch 
 glass, and heat be cautiously applied, violet vapours 
 having the characteristic odour of indigotin will soon 
 make their appearance, and condense on the cool part 
 of the watch glass. 
 
 Bleaches 
 slowly. 
 
 Is slightly 
 less changed 
 than vat in- 
 digo. 
 
 May be found on all fibres. After treating with nitric 
 acid, sulphuric acid may easily be detected in the solu- 
 tion. The indigo cannot be separated by sublimation. 
 Moistened with protochloride of tin, it becomes green, 
 and afterwards yellow. Vat indigo resists the actions 
 of these reagents a little better. 
 
 No altera- 
 tion takes 
 place. 
 
 Dirty green. 
 
 Is met with upon silk, wool, and cotton fibre ; be- 
 comes decolorised in presence of soap; fades in the 
 light. Is not attacked by weak acids. Protochloride of 
 tin and dilute hydrochloric acid produce no change. 
 
 Is decom- 
 posed. 
 
 The dark 
 shades be- 
 come brown, 
 the light ones 
 yellow. 
 
 Alone, it is of a dull, dark, and dirty tint ; but it is 
 often associated with indigo on woollen and cotton 
 fabrics ; and if used to top the indigo colour, it is dis- 
 solved by hydrochloric acid, whilst the indigo is not 
 affected. 
 
 The colour 
 is slowly des- 
 troyed ; more 
 rapidly upon 
 cotton than 
 upon wool or 
 silk. 
 
 Slowly de- 
 colorised. 
 
 Most frequently met with on silk and wool ; and also 
 on cotton and linen, on which it is fixed by albumen or 
 sumach. Nitric acid gives a dark blue coloration at 
 first, which afterwards becomes yellowish-blue. Under 
 the influence of protochloride of tin and hydrochloric 
 acid it suffers but little change ; sometimes it becomes 
 greenish, but recovers its colour when brought in con- 
 tact with water. It behaves in a similar manner with 
 concentrated hydrochloric acid. 
 
 
 
 Is only employed for printing; it is generally fixed 
 with white of egg, consequently, on burning the tissue, 
 even if it be cotton, products are formed similar to 
 those obtained when nitrogenous bodies are burnt 
 (smell of burnt horn, ammonia reaction). 
 
 
 
Name of the 
 colouring matter. 
 
 Combustion of the 
 coloured fibre on a 
 piece of platinum. 
 
 Boiling in water 
 
 'ontaining J per cent. 
 
 of soap. 
 
 Immersion in dilute 
 nitric acid. 
 
 Quercitron bark. 
 
 The ash contains 
 alumina. 
 
 The water be- 
 comes coloured, but 
 the colour of the 
 cloth is not much 
 altered. 
 
 Becomes brown. 
 
 Persian berries. 
 
 The ash contains 
 alumina, or if the 
 coloration is more 
 orange, tin is present. 
 
 Behaves like the 
 preceding. 
 
 As the preceding. 
 
 Old fustic. 
 
 The ash contains 
 alumina. 
 
 Almost decolor- 
 ised. 
 
 As the preceding. 
 
 Weld. 
 
 The ash contains 
 alumina, and some- 
 times, although rare- 
 ly, tin. 
 
 Only slightly al- 
 tered. 
 
 Little changed. 
 
 Barberry root. 
 
 Is not used with 
 mordants. 
 
 Little changed. 
 
 Red-brown, as is 
 also the liquid. 
 
 Turmeric. 
 
 Generally used 
 without mordants. 
 
 Rapidly becomes 
 brown, but recovers 
 its colour by the 
 action of acids. 
 
 Little changed. 
 
 Annatto. 
 
 Used without mor- 
 dants. 
 
 Takes a darker 
 shade. 
 
 At first reddish- 
 brown, then yellow- 
 ish-green, and lastly 
 becomes bleached. 
 
 Picric acid. 
 
 Used without mor- 
 dants. 
 
 Loses its yellow 
 colour. 
 
 Little alteration. 
 
 Chrome yellow 
 and chrome orange. 
 
 Lead will be found 
 in the ash. 
 
 Becomes more 
 orange. 
 
 Decolorises. 
 
 Ochre. 
 
 Reddish - brown 
 ash, containing ox- 
 ide of iron. 
 
 Generally more 
 brilliant, otherwise 
 no change. 
 
 Is destroyed im- 
 mediately. 
 
 Orpiment. 
 
 The vapours 
 arising from the 
 burning cloth have 
 the smell of sulphur- 
 ous acid and garlic. 
 
 Little change. 
 
 Little change. 
 
Treating in a hot 
 
 ■mixture ofioo c.c 
 nitric acid, sp.gr, 
 i'5, 6 vols, water 
 and 4.0 vols, of al- 
 cohol. To the ex- 
 tract a few drops 
 of acetate of lead 
 solution a re added. 
 
 Immersion in 
 caustic ammonia. 
 
 Remarks. 
 
 The acid extract 
 is yellow. The 
 voluminous pre- 
 cipitate pale yel- 
 low. 
 
 Whilst wet it 
 appears brown, 
 but when dry is 
 found to have 
 changed very little. 
 
 The reactions of this and the two following 
 colouring matters are very similar, the chemi- 
 cal nature of the colouring principle being 
 analogous. 
 
 The same as 
 the preceding. 
 
 The tone 
 changes a little; 
 colour slightly 
 dissolved. 
 
 Persian berries are only used for printing, 
 and not for dyeing. They are employed 
 with a salt of alumina as a mordant for 
 yellow, and a salt of tin for orange; the 
 latter, however, is not a good tint. 
 
 As the preced- 
 ing. 
 
 Becomes col- 
 oured orange ; 
 the liquid be- 
 comes coloured 
 also. 
 
 If the extract obtained by nitric acid and 
 alcohol be evaporated, and a little concen- 
 trated sulphuric acid then added, a red 
 coloration is produced, which is more intense 
 upon wool than on cotton fibre (rufimoric acid). 
 
 Like the pre- 
 ceding. 
 
 Slightly altered. 
 
 This colouring matter is employed for 
 every sort of fibre. 
 
 No visible pre- 
 cipitation. 
 
 Red-brown. 
 
 Is only employed for dyeing silk. 
 
 Dense orange - 
 brown precipi- 
 tate. 
 
 Reddish-brown 
 coloration. 
 
 Is seldom employed alone; generally with 
 other yellow pigments. 
 
 No visible pre- 
 cipitate. 
 
 Little altera- 
 tion. 
 
 Is not a pure yellow, but generally orange. 
 
 No precipitate. 
 
 Clear yellow ; 
 loses a little of 
 its colour. 
 
 Only dyes silk and wool ; is generally met 
 with only on the former. A solution of cy- 
 anide of potassium colours it red-brown; 
 which reaction must not be confounded with 
 that of the alkalis with turmeric. 
 
 
 The colour is 
 partially remo- 
 ved, and becomes 
 orange-yellow. 
 
 
 
 Is destroyed, 
 the solution con- 
 tains iron. 
 
 No alteration. 
 
 If a little hydrochloric acid be first added, 
 and then some potassium ferrocyanide, a blue 
 coloration is produced. 
 
 
 Greater part 
 dissolves. 
 
 Very little employed. 
 
 
486 
 
 III.— RED COLOURING 
 
 me of the 
 colouring matter. 
 
 Combustion on a \ Boiling in - 
 piece of platinum containing \ per 
 foil. cent, of soap. 
 
 Moistened 'with a 
 solution of carbon- 
 ate of soda. 
 
 Cochineal. 
 
 The ashes contain 
 alumina, or oxide 
 of tin, or both these 
 bases. 
 
 The colour is but 
 little changed, the 
 liquid is a faint violet 
 colour. 
 
 The liquid is 
 coloured a little with- 
 out perceptibly al- 
 tering the colour of 
 the fibre. 
 
 Brazil wood. 
 
 Ashes generally 
 contain alumina. 
 
 The colour dis- 
 appears ; the liquid 
 becomes red-brown. 
 
 The liquid quickly 
 becomes coloured, 
 the fibre remains 
 red. 
 
 Madder reds. 
 
 Alumina will be 
 found in the ashes. 
 
 The colour be- 
 comes brighter. 
 
 A little colour is 
 removed, but the 
 shade remains un- 
 changed. 
 
 Safnower. 
 
 The ash does not 
 contain any mor- 
 dant. 
 
 Quickly and com- 
 pletely decolorised. 
 
 The fibre becomes 
 flesh-coloured, and 
 acquires a yellowish 
 tint. 
 
 Murexide. 
 
 The fibre contains 
 a little oxide of lead 
 or mercury, (the 
 latter is detected by 
 heating a piece of 
 the cloth in a tube). 
 
 Is moderately per- 
 manent. 
 
 Becomes lilac- 
 coloured ; a little of 
 the colour is re- 
 moved. 
 
 Aniline reds. 
 
 The ash generally 
 does not contain a 
 mordant. 
 
 Become more bril- 
 liant upon wool at 
 first, and is then 
 rapidly discolored. 
 
 Preserves its 
 colour well. 
 
MATTERS. 
 
 487 
 
 Immersion in 
 
 caustic ammonia. 
 
 Moistened ivith a 
 
 solution of citric 
 
 acid. 
 
 Moistened ivith a 
 solution of equal 
 parts of tin salt, 
 hydrochloric acid, 
 and water. 
 
 Remarks. 
 
 A little of the 
 colour is removed; 
 the liquid becomes 
 violet. 
 
 Becomes yellow, 
 and the colour can- 
 not be completely 
 restored by ammo- 
 nia. 
 
 A little of the 
 colour is removed; 
 the fibre becomes 
 yellow. 
 
 On silk, wool, 
 and cotton. 
 
 Much colour is 
 removed. Cotton 
 is almost decolor- 
 ised. 
 
 Reddish -yellow; 
 the colour is res- 
 tored by ammonia. 
 
 The tissue be- 
 comes tinted yel- 
 low. 
 
 On silk and 
 cotton, rarely on 
 wool. The colour 
 fades in presence of 
 soap. 
 
 On wool and silk 
 rather brown; but 
 Turkey reds and 
 alumina reds on 
 calico undergo but 
 slight change. 
 
 Unaltered. 
 
 Almost unaltered ; 
 only a little of the 
 colour is removed. 
 
 Resists the action 
 of all reagents 
 better than other 
 reds. 
 
 The fibres and 
 the liquid become 
 reddish-yellow. 
 
 Is permanent. 
 
 It assumes a fine 
 straw-yellow colour 
 
 Is not met with 
 upon wool ; most 
 generally upon silk, 
 sometimes also on 
 cotton. 
 
 Retains its colour 
 well. 
 
 Bleaches quickly. 
 
 Quickly becomes 
 grey. 
 
 It was met with 
 often on dyed and 
 printed cotton 
 goods, but more 
 frequently upon 
 wool; it is now 
 rarely employed. 
 
 Becomes pale rose- 
 red, then colour- 
 less. When the 
 ammonia absorbed 
 by the fibre has 
 evaporated the 
 colour is restored. 
 
 Stands well. 
 
 Is decolorised 
 gradually in places 
 which are only 
 slightly touched by 
 the reagent ; the 
 fibre becomes blue 
 before being de- 
 colorised. 
 
 On wool and 
 silk. 
 
4 88 IV.— GREEN COLOURING 
 
 The ashes contain neither iron nor lead. 
 
 In this group may be classed : ist, Indigo-blue and vegetable yellow; 2nd, Log- 
 wood blue and a vegetable yellow ; 3rd, Lo-kao ; 4th, Aniline green ; 5th, Aniline 
 blue and picric acid, or vegetable yellow; 6th, (Scheeles green or arsenite of 
 copper) ; 7th, Oxide of chromium. 
 
 la. Vat indigo may be recognised by heating a piece of the cloth in a porcelain 
 capsule; the indigo volatilises (see blue colouring matters). 
 
 lb. Carmine of indigo does not give this reaction. They both become greenish- 
 yellow when moistened with tin salt and hydrochloric acid. Nitric acid decom- 
 poses both, leaving the yellow colour but slightly altered. The ashes of both con- 
 tain alumina, in consequence of salts of that base being employed as mordants for 
 the yellow colour. 
 
 2. Logwood blue and vegetable yellow. Hydrochloric acid produces a yellow- 
 ish-red coloration ; the liquid becomes yellowish, but blue or green on the addition 
 of an alkali. Alumina is contained in the ashes. 
 
 No satisfactory method is yet known for determining the yellow vegetable 
 colouring matter which is mixed with the blue colour. 
 
 3. Chinese green (lo-kao). No mordant base in the ash, but sometimes a little lime. 
 Does not change in presence of acids or alkalis if they are not too concentrated. 
 It is only used for dyeing silk, but is now rarely found. 
 
 4. Aniline green. No mordant base in the ash. Moistened with hydrochloric 
 acid (concentrated) it immediately becomes yellow, or even colourless. The colour 
 is, however, again restored when water is added. 
 
 5. Aniline blue, and vegetable yellow or picric acid. The blue is not altered 
 by chloride of tin and hydrochloric acid. This mixture is rarely met with. 
 
 6. Scheele's green. Fused with carbonate of soda it gives in the reducing flame 
 of the blowpipe, a globule of metallic copper. Heated in a small open glass tube, 
 it gives a deposit of arsenious acid, and a smell of garlic. 
 
 7. Oxide of chromium. Fused with a little potassium nitrate, it gives a yel- 
 low soluble mass, which, mixed with a little acetic acid and a solution of acetate of 
 lead, gives a yellow precipitate. It is only employed for printing fibres. 
 
MATTERS. 
 
 489 
 
 The ashes contain lead but 
 
 8. Chrome yellow and 
 indigo blue. 
 
 A piece of the cloth 
 soaked in soda-ley becomes 
 more blue, and the solution 
 contains a little chromate 
 of potash. Chloride of 
 lime leaves the yellow, but 
 destroys the blue. The 
 ashes fuse into an incan- 
 descent bead of a brownish 
 yellow color, which, if mix- 
 ed with carbonate of soda 
 and again fused, leaves a 
 globule of metallic lead. 
 
 The ashes contain iron but 
 no lead. 
 
 9. Prussian blue and 
 vegetable yellow. Placed 
 in caustic soda solu- 
 tion, the piece becomes 
 brown-yellow : if a little 
 hydrochloric acid be added 
 to the filtered liquid and 
 then perchloride of iron, a 
 blue or greenish-blue pre- 
 cipitate will be produced. 
 
 The ashes contain iron 
 and lead. 
 
 10. Prussian blue and 
 chromate of lead. The 
 lead may be detected as 
 given in No. 8 by re- 
 duction to the metallic 
 state. The chromic acid 
 remains in combination 
 with the soda, so that 
 the product of the fu- 
 sion, dissolved in water, 
 gives with acetic acid 
 and acetate of lead, a 
 yellow precipitate. 
 
490 
 
 V.— PURPLE 
 
 Name of the colour. 
 
 Moistened with concen- 
 trated hydrochloric acid. 
 
 Moistened ivith a mixture 
 
 of equal parts of chloride 
 
 of tin, hydrochloric acid, 
 
 and water. 
 
 Perkin's aniline purple 
 (prepared with chromic 
 acid). 
 
 Becomes blue, but re- 
 covers its original colour 
 when immersed in water. 
 
 Almost unchanged. 
 
 Aniline purple obtained 
 with magenta and aniline. 
 
 Becomes green ; the 
 
 liquid a little reddish. 
 Placed in water it takes 
 its original colour. 
 
 Same reaction as that 
 with hydrochloric acid. 
 
 Hofmann's aniline violet, 
 obtained with iodide of 
 ethyl. 
 
 Becomes yellow, some- 
 times taking a green 
 coloration previously ; its 
 colour is also restored by 
 placing it in water. 
 
 Ditto. 
 
 Madder purples. 
 
 Becomes red-brown. 
 Water does not restore its 
 colour. 
 
 Becomes of a slightly 
 reddish-brown. The li- 
 quid takes up very little 
 colour. 
 
 Alkanet. 
 
 Becomes more lilac- 
 colored, but none of the 
 colour is removed. 
 
 Undergoes but little 
 alteration, which is less 
 marked as the colour is 
 more blue. 
 
 Orchil. 
 
 Becomes clearer; rather 
 brick-red. 
 
 Is immediately and 
 completely decolorised. 
 
 Logwood purple. 
 
 Becomes red; much of 
 the colour is removed, and 
 the solution becomes red. 
 
 Fades much to violet- 
 red. 
 
COLOURS. 
 
 491 
 
 Immersion in a solution 
 
 of ammonia. 
 
 Immersion in a solution 
 
 of carbonate of potash or 
 
 soda. 
 
 Remarks. 
 
 Loses brilliancy. 
 
 Becomes blue. 
 
 For wool and silk, no 
 mordant base in the ash. 
 For cotton sometimes 
 alumina. 
 
 Ditto. 
 
 Unchanged. 
 
 Same as the preceding 
 colour. 
 
 Ditto. 
 
 Ditto. 
 
 Ditto. 
 
 Ditto. 
 
 Rather more violet, but 
 none of the colour is re- 
 moved. 
 
 The ash contains iron. 
 Almost exclusively em- 
 ployed for cotton goods. 
 
 Ditto. 
 
 Little changed, none of 
 the colour is removed. 
 
 On silk and cotton. No 
 mordant base in the ash. 
 
 Becomes violet-blue. 
 
 At the ordinary tem- 
 perature the colour is 
 rather bluish. If warmed 
 the solution also becomes 
 coloured violet-blue. 
 
 No mordant base. Is 
 found on wool, silk, or 
 cotton, often with a blue 
 or brown-red shade, pro- 
 duced by indigo or co- 
 chineal. These colours 
 do not generally affect the 
 reactions. 
 
 The colour fades to vio- 
 let, as dark as that pro- 
 duced by the acid solution. 
 
 Same as with ammonia. 
 
 The ash contains oxide 
 of tin. 
 
492 
 
 VI.— BROWN 
 
 Name of the colour. 
 
 Moistened with concen- 
 trated hydrochloric acid. 
 
 Moistened with a solution 
 
 of equal parts of tin salt, 
 
 hydrochloric acid, and 
 
 water. 
 
 Madder. 
 
 Becomes red or orange- 
 colored. Ammonia re- 
 stores the original colour. 
 
 Same reaction as with 
 hydrochloric acid. 
 
 Catechu. 
 
 Stands well; if other 
 colouring matters have 
 been employed with it, it 
 only becomes of a lighter 
 shade. 
 
 Same reaction as with 
 hydrochloric acid. 
 
 Browns produced with 
 various woods (logwood, 
 and a red dyewood). 
 
 Destroyed, and violet 
 coloration produced. 
 
 Destroyed, and violet 
 coloration produced. 
 
 Manganese. 
 
 Little alteration. 
 
 Is slowly decomposed. 
 
 Brown produced by the 
 employment of blue, yel- 
 low, and red upon wool. 
 
 a. — Ground or bottom 
 of indigo. 
 
 b. — Ground or bottom 
 of Prussian blue. 
 
 Is not alterated, the 
 blue resists the action 
 well. 
 
 Becomes green. Not 
 much altered. The blue 
 resists the action well. 
 
COLOURS. 
 
 493 
 
 Burning on apiece of platinum foil. 
 
 Remarks. 
 
 The ash contains oxide of iron and 
 alumina. 
 
 Only employed for colouring cotton, 
 linen, and hempen fibres. 
 
 Ashes greenish-grey. Heated with 
 borax before the blow-pipe it gives a 
 green glass. 
 
 This colour is rarely produced by the 
 employment of catechu and bichromate 
 of potash only ; but logwood, carmine of 
 indigo, orchil, or turmeric are generally 
 employed at the same time, to produce 
 various shades. These substances ren- 
 der its detection difficult ; the chromium 
 in the ash, and a certain resistance to 
 the action of acids, are characteristic. 
 
 The ash contains alumina and some- 
 times also oxide of iron. 
 
 Besides these two woods, others are 
 employed for making brown. The re- 
 actions are then less certain. 
 
 The ash contains manganese, which 
 gives a red coloration to a bead of 
 borax. 
 
 Now little employed. This colouring 
 matter gives a good shade. Is some- 
 times employed with indigo to produce 
 a deep blue. 
 
 The ash contains alumina ; and when 
 the ground is of Prussian blue, also 
 oxide of iron. 
 
 It is often difficult to identify this 
 in consequence of the simultaneous pre- 
 sence of different substances. 
 
494 
 
 VII— BLACK AND GREY 
 
 Name of the colour. 
 
 Burning upon a piece of 
 platinum foil. 
 
 Immersion in hydrochloric 
 acid. 
 
 Logwood (iron mordant). The ash contains oxide 
 1 of iron. 
 
 Is decolorised, giving 
 a cherry-red colour. 
 
 Tannin. 
 
 Ash contains oxide of 
 iron. 
 
 White spots, becoming 
 rust-colored by ammonia. 
 
 Chrome black. The ash contains oxide 
 of chromium. 
 
 Becomes reddish. 
 
 Madder black. The ash contains oxide 
 of iron and alumina. 
 
 Becomes red ; the colour 
 is restored by ammonia. 
 
 Black, with bottom or 
 ground of vat indigo. 
 
 Ash contains a little 
 iron. 
 
 Becomes blue. 
 
 Aniline black. 
 
 Very light ash. 
 
 After some time a green 
 shade appears. 
 
COLOURS. 
 
 495 
 
 Immersion in a mixture of equal farts 
 of chloride of tin, water, and hydro- 
 chloric acid. 
 
 Remarks. 
 
 Violet, fades quickly. 
 
 
 Same reaction as with hydrochloric 
 acid. 
 
 
 Violet, a rather large quantity of the 
 colour is removed. 
 
 
 Same reaction as with hydrochloric 
 acid. 
 
 Is only employed for printing. 
 
 Becomes greenish-blue. 
 
 It is the beautiful black which is 
 formed upon wool. If care be first 
 taken to remove by dilute acid any gal- 
 late of iron or logwood, the indigo may 
 then be recognised as directed in the 
 table for blue colouring matters. 
 
 Becomes rapidly green, then greenish- 
 grey; the colour is not restored by 
 water, but is by ammonia. 
 
 Is almost exclusively employed for 
 printing on cotton. 
 
INDEX. 
 
 Page. 
 
 ABIES canadensis 328 
 
 Acacia ba?nbolah 327 
 
 ,, catechu 330 
 
 ,, nilotica 327 
 
 Acetophenone 169 
 
 Acetylrhamnetin 273 
 
 Acid, aloeresic 282 
 
 ,, aloeretic 282 
 
 ,, aloetic 282 
 
 ,, anchusic 134 
 
 ,, anthraflavic 44 
 
 ,, anthranilic 167 
 
 ,, P-usnic 245 
 
 ,, bezoardic 321 
 
 ,, bromisatic 166 
 
 ,, bnmolic 428 
 
 ,, cachoutannic 333 
 
 ,, carbazotic (picric) 452 
 
 ,, carminic 209 
 
 ,, carthamic 136, 137 
 
 ,, catechuic 334 
 
 ,, catechutannic 333 
 
 ,, chloranilic 166 
 
 ,, chloroxynaphthalic 474 
 
 ,, chrysammic 283 
 
 ,, chrysammidic 284 
 
 ,, chrysanilic 167 
 
 ,, chrysophanic 296, 298 
 
 ,, chrysinic 296 
 
 ,, cladonic 245 
 
 ,, dibromisatic 166 
 
 „ digallic 313 
 
 ,, ellagic 321 
 
 ,, erythric 239 
 
 ,, euxanthic 297 
 
 ,, evernic 245 
 
 ,, everninic 245 
 
 „ gallic 313 
 
 ,, gallotannic 311 
 
 , , hydrindic 1 70 
 
 ,, hyposulphindigotic 177 
 
 ,, indigotic 162 
 
 ,, isamic 161 
 
 ,, isatic 160 
 
 ,, isopurpuric 456 
 
 HH 
 
 Page. 
 
 Acid, iso-uvitic 295 
 
 „ japonic 335 
 
 ,, lecanoric 240 
 
 ,, meta-amidobenzoic 167 
 
 ,, metagallic 312, 317 
 
 , , mimotannic 333 
 
 ,, moric 264,266 
 
 ,, morintannic 264 
 
 ,, naphthalene-sulphonic ... 471 
 
 ,, naphthylpurpuric 473 
 
 ,, nitrocinnamic 172 
 
 ,, nitrococcusic 213 
 
 ,, nitrosalicylic 162 
 
 ,, nitroxynaphthalic 475 
 
 ,, orsellesic 246 
 
 ,, orsellic 241 
 
 ,, orsellinic 246 
 
 ,, oxalic, from garancin 
 
 washings 86 
 
 ,, oxynaphthalic 56 
 
 ,, oxyphenic 336 
 
 ,, oxytoluic 360 
 
 ,, paracoumaric 282 
 
 ,, paraoxybenzoic 282 
 
 ,, parellic 247 
 
 ,, phenylcarbamic 167 
 
 ,, picramic 456 
 
 ,» Pjcric 163, 452 
 
 , , picrocyamic 456 
 
 ,, protocatechuic. . 258, 264, 335 
 
 , , pyrocatechuic 336 
 
 ,, pyrogallic 316 
 
 ,, quercetic 257,258 
 
 ,, quercimeric 258 
 
 ,, quercitannic 255, 328 
 
 ,, regianic 329 
 
 ,, rhotic 329 
 
 ,, rocellic 247 
 
 ,, rosolic 458 
 
 ,, ruberythric 35 
 
 ,, rubiacic 30, 33 
 
 ,, rubianic 36 
 
 ,, rubinic 335 
 
 „ rufigallic 315 
 
 ,, rufimoric 265 
 
498 
 
 INDEX. 
 
 Page. 
 
 Acid, rufitannic 313 
 
 ,, salicylic 163 
 
 ,, santalic 129 
 
 ,, styphnic 123 
 
 ,, sulphindigotic 176 
 
 ,, sulphoflavic 181 
 
 ,, sulphonaphthalic 471 
 
 ,, sulphopurpuric 175, 181 
 
 ,, sulphorufic 181 
 
 ,, sulphoviridic 180 
 
 ,, sulphurous, bleaching ac- 
 tion of 16 
 
 ,, taiguic 300 
 
 ,, tannic 311 
 
 ,, tannoxylic 313 
 
 ,, tribromomoric 266 
 
 ,, triphenylrosaniline-sulpho- 
 
 nic 4°7 
 
 ,, uric 225 
 
 ,, usnic 244 
 
 ,, vulpic 296, 297 
 
 ,, xylochloeric 309 
 
 Acids, action of on indican 150 
 
 , , indigosulphonic 1 75 
 
 Action of acids on indican 1 50 
 
 ,, alkalis on indican 155 
 
 ,, chlorine on colouring 
 
 matters. 13 
 ,, j, indigo ... 164 
 ,, electricity on flowers.. 10 
 ,, light on guaiacum ... 6 
 „ heat on colouring mat- 
 ters 11 
 
 Adrianople red 64 
 
 Adulteration of aniline yellow... 431 
 
 ,, annatto 289 
 
 ,, catechu 333 
 
 ,, cochineal 214 
 
 ,, madder 104 
 
 ,, magenta 379 
 
 Adulterations, detection of 348 
 
 Ageing 77 
 
 Al root in 
 
 Alcohol from madder 89 
 
 Aldehyde green 414 
 
 ,, violet 400 
 
 Aleppo galls 322 
 
 Alizaric extract 93 
 
 Alizarin, 25, 30, 32, 35, 38, 93, III 
 
 ,, anthracene, from 41 
 
 ,, artificial 44, 48, 54 
 
 ,, ,, Graebe's patent 50 
 
 ,, ,, printing with... ICO 
 
 ,, commercial 87 
 
 , , from anthracene 44 
 
 green 93 
 
 ,, hydrate 39 
 
 , , hydride of 40 
 
 , , optical characters of . . . 62 
 
 Page. 
 
 Alizarin, oxidation of 41 
 
 » yellow 93 
 
 Alizarinamide 42 
 
 Alizarinimide 43 
 
 Alkalis, action of on indican ... 155 
 
 Alkanet 134 
 
 Alloxan 226 
 
 Aloeresic acid 282 
 
 Aloeretic ,, 282 
 
 Aloeretin 282 
 
 Aloes 278 
 
 ,, Barbadoes 279 
 
 ,, Bombay 279 
 
 >, Cape 279 
 
 ,, colours yielded by 284 
 
 ,, hepatic 279 
 
 ,. liver 279 
 
 ,, Natal 279 
 
 ,, Socotrine 279 
 
 ,, Zanzibar 279 
 
 Aloetic acid 282 
 
 Alo'in 280 
 
 Amidoalizarin 42 
 
 Amidodinitrophenol 456 
 
 Amidodiphenylimide 429 
 
 Ammonia, hsemateate of 115 
 
 Ammoniacal cochineal 218 
 
 Ammonium lokaetin 304 
 
 Amylic orsellinate 242 
 
 Amylorcin 238 
 
 Analysis of white light 2 
 
 Anchusa tinctoria 134 
 
 Anchusic acid 134 
 
 Anchusin 134 
 
 Aniline 356 
 
 Aniline black, aniline for 445 
 
 ,, composition of .. . 442 
 
 „ Dullo's 439 
 
 , , Jarossen and Mid- 
 ler's 441 
 
 ,, Koechlin's 438 
 
 Lauth's 437, 439 
 
 ,, Lightfoot's 436 
 
 ,, ,, experi- 
 ments on 443 
 
 ,, nature of 442 
 
 ,, Persoz' 447 
 
 ,, Sacc's 438 
 
 ,, Schlumberger's. . 441 
 
 ,, Spirk's 440 
 
 Aniline blues 402 
 
 ,, ,, dyeing with 411 
 
 ,, browns 432 
 
 ,, commercial 362 
 
 ,, discovery of 352 
 
 ,, for aniline black 448 
 
 ,, from coal-tar 353 
 
 ,, from indigo 169, 353 
 
 „ greens 414 
 
INDEX. 
 
 499 
 
 Page. 
 
 Aniline grey, Laiiber's 448 
 
 ,, heavy 363 
 
 „ light 363 
 
 ,, manufacture of 356 
 
 ,, maroons 432 
 
 „ violets 3S4 
 
 ,, yellow, adulteration of.. 431 
 
 , , yellows 425 
 
 Animal charcoal 14 
 
 Annatto 288 
 
 ,, adulteration of 289 
 
 ,, composition of 288 
 
 „ reactions of 289 
 
 ,, uses of 291 
 
 Anthracene 46 
 
 ,, alizarin from 44 
 
 , , discovery of 44 
 
 ., from alizarin 41 
 
 ,, orange 55 
 
 ,, purification of 46 
 
 ,, properties of 47 
 
 Anthraflavic acid 44 
 
 Anthranilic acid 167 
 
 Anthrapurpurin 45 
 
 Anthraquinone 49 
 
 Apparatus for evaporation 147 
 
 Arcca catechu 330 
 
 Artificial alizarin 44, 4S, 54 
 
 ,, ,, Graebe's patent 50 
 
 ,, ,, printing with... 100 
 
 Assistant liquor, purple 73 
 
 Aurin 466 
 
 Azodinaphthyldiamine 477 
 
 Azodiphenyl blue 411 
 
 Azodiphenyldiamine 429 
 
 Azolitmin 248 
 
 Azoresorcin derivatives 250 
 
 Azulin 464 
 
 BABLAH 327 
 
 Babool 327 
 
 Bahia wood 122 
 
 Baphia nitida 128 
 
 Baraniline 363 
 
 Barbadoes aloes 279 
 
 Barbaloin 280 
 
 Barberry root 292 
 
 Bardy's process for blue & violet 405 
 Barwood 128, 131 
 
 , , reactions of 132 
 
 Bengal catechu 331 
 
 Benzene 353 
 
 Benzidam 352 
 
 Benzoylalizarin 43 
 
 Benzyl chloride 399 
 
 Benzylic violets 399 
 
 Berberine 293 
 
 Berber is aristata 293 
 
 ,, vulgaris 292 
 
 Page. 
 Berlin lake 128 
 
 ]3-ery thrin 247 
 
 P-orcin 245, 247 
 
 p-usnic acid 245 
 
 Bezoardic acid 321 
 
 Bigonia cliica 291 
 
 Binitroanthraquinone 50 
 
 Bixia orellana 288 
 
 Bixin 290 
 
 Black, aniline 435 
 
 ,, logwood 120 
 
 ,, mordant 75 
 
 Bladder green 305 
 
 Blanco 208 
 
 Bleaching action of sulphurous 
 
 acid 16 
 
 Bleu de Lyon 402 
 
 ,, ,, manufacture of 403 
 
 ,, Mulhouse 402 
 
 ,, Nemours 131 
 
 ,, Paris 402 
 
 Bleu lumiere 404 
 
 Blue and violet, Bardy's process 
 
 for 40S 
 
 ,, azodiphenyl 41 1 
 
 ,, diphenylamine 408, 410 
 
 ,, Nicholson's 407 
 
 ,, night 4°4 
 
 ,, Runge's 388 
 
 ,, Saxony 178 
 
 , , toluidine 4°8 
 
 Blues, aniline 402 
 
 Bombay catechu 331 
 
 Brazilwood 121 
 
 ,, dyeing with 126 
 
 ,, extract 125 
 
 ,, ,, reactions of... 125 
 
 „ rose colour 127 
 
 Brazile'in 124 
 
 Brazilin 123 
 
 Britannia violet 400 
 
 Bromalizarin 43 
 
 Bromaloin 281 
 
 Bromisatic acid 166 
 
 Bromisatin 166 
 
 Bromobenzene 359 
 
 Bromorcins ." 236 
 
 Brou-de-noix 329 
 
 Brown, Girard and De Laire's ... 432 
 
 ,, Jacobsen's 433 
 
 ,, Koechlin's 433 
 
 ,, Sieberg's 434 
 
 Wise's 434 
 
 Browns, aniline 432 
 
 Brunolic acid 458 
 
 Butea frondosa 330 
 
 CMSALPINJA brazilicnsis ... 121 
 
5oo 
 
 IXDEX. 
 
 Page. 
 
 Ccesalpinia christa 121 
 
 ,, coriaria 328 
 
 ,, eckiiuita 122 
 
 ,, sappan 122 
 
 Cachoutannic acid 333 
 
 Caliatour wood 133 
 
 Calico printing 72 
 
 California wood 122 
 
 Calumbo root 293 
 
 Campeachy wood 113 
 
 Campo Bello yellow 469 
 
 Camwood 128 
 
 Cape aloes 279 
 
 Carajara 291 
 
 Carbazotic acid 452 
 
 Carmin de pourpre 227 
 
 Carminamide 218 
 
 Carminaphtha 475 
 
 Carmine 209, 219 
 
 „ indigo 178, 179 
 
 ,, lakes 218 
 
 „ red 211 
 
 sorgho 134 
 
 Carminic acid 209, 212 
 
 Carotin 301 
 
 Carthamic acid 136,137 
 
 Carthamin 136, 137 
 
 Carthamus tinctorius 1 36 
 
 Casthelaz grey 449 
 
 Catechin 334 
 
 Catechu 330 
 
 ,, adulteration of 333 
 
 „ Bengal 331 
 
 ,, Bombay 331 
 
 ,, brown 337 
 
 „ dyeing with 337 
 
 ,, Gambier 331 
 
 ,, reactions of 332 
 
 Catechuic acid 334 
 
 Catechuretin 335 
 
 Catechutannic acid 333 
 
 Cerise 382 
 
 Cetraria vidpina 296 
 
 Chalk, use of in madder dye- 
 ing 27, 81 
 
 Charbon de garance 25 
 
 Charcoal 13 
 
 ,, animal 14 
 
 Chayaver 108, no 
 
 Chesnutbark 328 
 
 Chica 291 
 
 China blue 203 
 
 Chinese galls 323 
 
 „ green 301 
 
 ,, sugarcane 133 
 
 Chintz 72 
 
 Chloralo'in 281 
 
 Chloranil 166 
 
 Chloranilic acid 166 
 
 Page. 
 Chlorine, action of on colouring 
 
 matters. 1 3 
 ,, ,, indigo... 164 
 
 Chlorisatin 165 
 
 Chlorogenin 28, 29 
 
 Chlorophyll 305 
 
 ,, composition of 308 
 
 ,, printing with 309 
 
 Chlororcins ... 236 
 
 Chlorotoluene 399 
 
 Chloroxynaphthalic acid 474 
 
 Chloroxynaphthaquinone 474 
 
 Chocolate chromium 99 
 
 ,, mordant, dark 75 
 
 light 75 
 
 Chromium chocolate 99 
 
 Chrysammic acid 283 
 
 Chrysammidic acid 284 
 
 Chrysanilic acid 167 
 
 Chrysaniline 425 
 
 Chrysinic acid 296 
 
 Chrysophanic acid 296 
 
 Chrysopicrin 296 
 
 Chrysorhamnin 271, 272 
 
 Chrysotoluidine 367, 426 
 
 Cladonia rangiferina 245 
 
 Cladonic acid 245 
 
 Clearing madder dyed goods ... 83 
 
 ,, Turkey red 68 
 
 ,, with hypochlorite of 
 
 soda 84 
 
 Coal-tar, aniline from 353 
 
 ,, colours 350 
 
 , , constituents of 350 
 
 ,, distillation of 352 
 
 ,, naphtha 352 
 
 Coccigranum 220 
 
 Coccinin 212 
 
 Cocculus palmatus 293 
 
 Coccus cacti 206 
 
 ,, ilia's 220 
 
 ,, lacca or ficus 206 
 
 ,, Polonkus radkens 206 
 
 Cochineal 206, 207 
 
 ,, adulteration of 214 
 
 ,, ammoniacal 218 
 
 ,, dyeing with 216 
 
 ,, history 206 
 
 , , preparation of 208 
 
 ,, reactions of 213 
 
 ,, testing 215 
 
 Cceloclim polycarpa 293 
 
 Coerulem 319 
 
 Coerulin 320 
 
 Cohen's vat (indigo) 199 
 
 Cold vat (indigo) 197 
 
 Colombo root 293 
 
 Colorometer 342 
 
 Colour, cause of 2 
 
INDEX. 
 
 501 
 
 Page. 
 Colour, recovery of waste 101, 102 
 
 Colour-giving principles 2 
 
 Colouring matters 2, 7 
 
 ,, action of chlo- 
 rine on 13 
 
 Colouring matters, action of 
 
 heat on 11 
 
 Colouring matters of flowers ... 7 
 
 ,, nature of 3 
 
 Colours 1 
 
 ,, coal-tar 350 
 
 ,, cresol 469 
 
 ,, effect of heat on 20 
 
 ,, fast 19 
 
 ,, loose 19 
 
 ,, naphthalene 470 
 
 ,, obtained from aloes 284 
 
 ,, on cloth, madder 107 
 
 ,, spectroscopic examina- 
 tion of 346 
 
 Columbo wood 293 
 
 Commercial alizarin 87 
 
 „ aniline 362 
 
 ,, indigo 189 
 
 Comparison of dyestuffs 347 
 
 Composition of aniline black . . . 442 
 
 ,, annatto 288 
 
 ,, chlorophyll 308 
 
 ,, cochineal 209 
 
 ,, gamboge 295 
 
 ,, madder 24 
 
 ,, safflower 136 
 
 ,, shell-lac 224 
 
 ,, stick-lac 222 
 
 ,, turmeric 285 
 
 Constituents of coal-tar 350 
 
 Corallin 459 
 
 ,, red 462 
 
 ,, yellow 466 
 
 Coriaria myrtifolia 324 
 
 Cotton, dyeing with indigo 199 
 
 Cresol colours 469 
 
 Crocin 292 
 
 Crocus sativus 292 
 
 Croton tinctorium 249 
 
 Crystallin 352 
 
 Crystallised green 420 
 
 Cudbear 247 
 
 Curcuma longa 284 
 
 „ tinctoria 284 
 
 Curcumin 285 
 
 Cutch 330 
 
 Cyanin 7, 135 
 
 Cynips folii qtiercus 321 
 
 DARK chocolate mordant 75 
 
 ,, purple mordant 73 
 
 ,, red mordant 74 
 
 Datisca cannabina 258 
 
 Page. 
 
 Dead oil 352 
 
 Decomposition of rubian 29 
 
 Detection of adulteration 348 
 
 ,, purpurin 63 
 
 Determination of tannin 338 
 
 Diacetylalizarin 41 
 
 Diamidonitrophenol 456 
 
 Diamylorcin 239 
 
 Diazoamidobenzene 429 
 
 Diazorescorcin 250 
 
 Diazoresorufin 250 
 
 Dibromindin 161 
 
 Dibromisatic acid 166 
 
 Dibromisatin 166 
 
 Dichlorisatin 165 
 
 Dichlorisatyde 166 
 
 Diethylorcin 239 
 
 Difference between garancin and 
 
 madder style 87 
 
 Digallic acid 313 
 
 Dimethyliodide of trimethyl- 
 
 rosaniline 416, 421 
 
 Dinitrobenzene 356 
 
 Dinitrocresol 469 
 
 Dinitronaphthol 471 
 
 Dinitrotoluenes 361 
 
 Dioxindol 1 70 
 
 Diphenylamine 409 
 
 ,, blue 408, 410 
 
 Diphenylrosaniline 39 1 
 
 Discoveiy of magenta 364 
 
 ,, of mauve 384 
 
 Discharge process (indigo) 201 
 
 Distillation of coal tar 352 
 
 Disulphisatyde 161 
 
 Dividivi 328 
 
 Dorothea violet 398 
 
 Dunging 78 
 
 Dutch yellow 275 
 
 Dyebeck 79 
 
 Dyeing cotton with indigo 199 
 
 ,, madder 81 
 
 , , power of garancin 86 
 
 ,, Turkey red 67 
 
 ,, with aniline blue 411 
 
 ,, ,, brazilwood 126 
 
 n catechu 337 
 
 ,, ,, cochineal 216 
 
 „ ,, indigo 196 
 
 „ „ logwood 119 
 
 ,, ,, lo-kao 304 
 
 „ magenta 374.377 
 
 ,, ,, old fustic 268 
 
 ,, ,, Persian berries 274 
 
 ,, ,, quercitron 261 
 
 ,, ,, safflower 138 
 
 ,, ,, sumach 326 
 
 ,, ,, turmeric 287 
 
 ,. weld 278 
 
502 
 
 INDEX. 
 
 Page. 
 
 Dyestuffs, comparison of 347 
 
 Dyewoods, red 113 
 
 EFFECT of heat on colours ... 20 
 
 Effects of salts on colours 18 
 
 Electricity, action of on flowers . 10 
 
 Ellagic acid 321 
 
 Emeraldine 414 
 
 D 25I 
 
 Ervthric acid 239 
 
 Er'vthrin 239 
 
 Erythrite 235, 243 
 
 Erythrobenzene 37 2 
 
 Ery throlein 248 
 
 Ery throlitmin 248 
 
 Erythromannite (erythrite) 243 
 
 Erythrozym 24, 25 
 
 Estimation of tannin 338 
 
 Ethylalizarin 43 
 
 Ethylaniline 398 
 
 Ethyldiphenylamine violet 399 
 
 Ethylic orsellinate 240, 242 
 
 Ethylorcin 238 
 
 Ethyhosaniline 393 
 
 Euxanthic acid 297 
 
 Euxanthone 298 
 
 Evaporation, apparatus for 147 
 
 Evernia prunastri 245 
 
 ,, vulpina 296 
 
 Evernic acid 245 
 
 Eveminic acid 245 
 
 Examination of mordants 348 
 
 Extract, alizaric 93 
 
 ,, of brazil wood 125 
 
 ,, ,, logwood 119 
 
 ,, ,, madder, Leitenber- 
 
 ger's ... 91 
 
 ,, „ orange 94 
 
 „ Paraf's ... 92 
 
 ,, » „ Pernod's... 95 
 „ ,, ,, . recipes for 
 
 dyeing with 96 
 
 ,, pectic 94 
 
 FAST colours 19 
 
 Femambuco wood 121 
 
 Flavin 260 
 
 Fleurs de garance 88 
 
 Florence lake 128 
 
 Florentine lake 220 
 
 Flowers, action of electricity on. 10 
 
 , , colouring matters of . . . 7 
 
 ,, of madder 89 
 
 Fluorescein 25 1 
 
 Fol's yellow 468 
 
 Formation of indigo 146 
 
 rosaniline 359 
 
 French purple 232 
 
 Furfurol (foot note) 85 
 
 Page. 
 
 Fustic 262 
 
 ,, dyeing with old 268 
 
 „ old 263 
 
 , , reactions of young 269 
 
 ,, young 268 
 
 Fu-tin 269 
 
 GALLEIN 318 
 
 Gallic acid 313 
 
 Gallin 318 
 
 Gallipoli oil 70 
 
 Gall-nuts 321 
 
 Gallotannic acid 311 
 
 Galls 321 
 
 ,, Aleppo 322 
 
 ,, Chinese 323 
 
 ,, Japanese 323 
 
 Gambier 330 
 
 ,, catechu 331 
 
 Gamboge 294 
 
 ,, composition of 295 
 
 pipe 294 
 
 Gambogia gtttta 294 
 
 Garanceaux 88 
 
 Garancin and madder style, 
 
 difference berween.. 87 
 
 , , dyeing power of 86 
 
 ,, extracting, with bisul- 
 phide of carbon ... 96 
 
 ,, from munjeet 109 
 
 , , manufacture of 84 
 
 ,, oxalic acid from wash- 
 ings 86 
 
 Garancine modifiee 85 
 
 Garcinia morella 294 
 
 Gardenia grandiflora 30 1 
 
 Garnet, Schultz 432 
 
 Gaidtheria procumbms 163 
 
 Geranosine 382 
 
 Goldgelb 469 
 
 Gopher wood 329 
 
 Grain colours 221 
 
 Grana fina 208 
 
 Granilla 208 
 
 Green, aldehyde 414 
 
 ,, alizarin 93 
 
 „ bladder 305 
 
 ,, Chinese 301 
 
 „ crystallised 420 
 
 ,, iodine 416 
 
 ,, methyl 422 
 
 ,, methylaniline 422 
 
 ,, Perkin's 422 
 
 .. sap 305 
 
 ,, soluble 420 
 
 ,, transformation of iodine 421 
 
 Greens, aniline 414 
 
 ,, from tertiary monamines 423 
 Grey Casthelaz 449 
 
INDEX. 
 
 503 
 
 Page. 
 
 Grey Laiiber's 448 
 
 Guaiacum, action of light on ... 6 
 Gum-kino 330 
 
 H^EMATEATE of ammonia... 115 
 
 Hsematein 115 
 
 Hrematin 114 
 
 Hematoxylin 114 
 
 ,, a test for lime car- 
 bonate 116 
 
 ,, reactions of 117 
 
 Hamaloxylon campechianumn^, 118 
 Heat, action of on colouring mat- 
 ters 11 
 
 , , effect of on colours 20 
 
 Heavy aniline 363 
 
 Hemlock spruce 328 
 
 ,, tree 328 
 
 Hennis 329 
 
 Hepatic aloes 279 
 
 Hoang-tchy 301 
 
 Hofmann gum 398 
 
 ,, violets 393 
 
 Huile tournante 69 
 
 Hydralizarin 36 
 
 Hydrastis canadensis ... 294 
 
 Hydride of alizarin 40 
 
 ,, purpurin 59 
 
 Hydrindic acid 170 
 
 Hydroberberine 294 
 
 Hydrochrysammide 284 
 
 Hydrocyanrosaniline 370 
 
 Hydrodiazoresorufin 250 
 
 Hypochlorite of soda, clearing 
 
 with 84 
 
 Hyposulphindigotic acid 177 
 
 Hyposulphites, reduction of in- 
 digo by 184 
 
 ILEX aquifolium 296 
 
 Ilixanthin 296 
 
 Imasatin 161 
 
 Imesatin 161 
 
 Indian vat 203 
 
 ,, yellow 297 
 
 Indican 147 
 
 ,, action of acids on 150 
 
 ,, ,, alkalis on 155 
 
 ,, leucin from 151, 154 
 
 Indicanin 155 
 
 Indifulvin 151 
 
 Indifuscin 151 
 
 Indiglucin 150, 153 
 
 Indigo 140 
 
 ,, action of chlorine on ... 164 
 
 , , aniline from 169, 353 
 
 ,, carmine 178, 179 
 
 ,, commercial 189 
 
 ,, dyeing cotton with 199 
 
 Page. 
 
 Indigo, dyeing with 196 
 
 ,, formation of 146 
 
 , , from urine 205 
 
 ,, manufacture 141 
 
 ,, printing 185 
 
 ,, pulverisation of 198 
 
 ,, purification of 188 
 
 ,, recovery of waste 197 
 
 ,, red 151 
 
 ,, reduction of, by hyposul- 
 phites 184 
 
 ,, testing 191 
 
 ,, white 182 
 
 Indigo/era: ... . 140 
 
 Indigopurpurin 173 
 
 Indigosulphonic acids 175 
 
 Indigotic acid 162 
 
 Indigotin 150, 158 
 
 ,, properties of 158 
 
 ,, pure 158 
 
 ,, synthesis of 169, 173 
 
 Indihumin 151, 153 
 
 Indin 161 
 
 Indiretin 151, 153 
 
 Indirubin 150, 151, 155 
 
 Indof. 171 
 
 Indophane 473 
 
 Injurious effects of rubiacin 81 
 
 Iodine green 416 
 
 , , transformation of. . . 42 1 
 
 Isalizarin 36 
 
 Isamic acid 161 
 
 Isamide 162 
 
 Isatic acid 160 
 
 Isatimide 162 
 
 Isatin 159 
 
 /satis indigotica 144 
 
 ,, iinctoria 143, 146 
 
 Isatyde 160 
 
 Isatofiavin 162 
 
 Isatopurpurin 162 
 
 Isatosulphites 162 
 
 Isodulcite 256 
 
 Isomorin 266 
 
 Isopurpurate of potassium 457 
 
 Isopurpuric acid 456 
 
 Iso-uvitic acid 295 
 
 JACOBSEN'S yellow 431 
 
 Jamaica wood 122 
 
 Japanese galls 323 
 
 Japonic acid 33c 
 
 Jaleorhiza palmata 293 
 
 Jola 220 
 
 KAMBE wood 128 
 
 Kermes 220 
 
 Kino 330 
 
 Knopperns 323 
 
504 
 
 INDEX. 
 
 Page. 
 
 Kopp's alizaric extract 93 
 
 ,, green alizarin 93 
 
 ,, purpurin 92 
 
 ,, violet 392 
 
 Kuphaniline 363 
 
 Kyanol 352 
 
 LAC 222 
 
 ,, dye 222, 224 
 
 ,, lake 224 
 
 Lacmus 248 
 
 Lake, Berlin 128 
 
 ,, Florence 128 
 
 ,, Florentine 220 
 
 ,, madder 103 
 
 „ Venetian 128 
 
 Lakes, carmine 218 
 
 Lawsonia inermis 329 
 
 Lecctno?-a tartarea 229, 241 , 247 
 
 Lecanoric acid 240 
 
 Lecanorin 241 
 
 Leitenberger's extract of madder 91 
 
 Leucaniline 370 
 
 Leuch's vat 204 
 
 Leucin from indican 151, 154 
 
 Leukaurin 467 
 
 Lichen, wall 296 
 
 Lichens 228, 296 
 
 „ testing 233 
 
 Light, analysis of 2 
 
 ,, aniline 363 
 
 ,, chocolate mordant 75 
 
 „ oil 352 
 
 ,, purple mordant 73 
 
 ,, red mordant 74 
 
 Lightfoot's experiments with ani- 
 line black 443 
 
 ,, process 186 
 
 Lima wood 122 
 
 Litmus 248 
 
 Liver aloes 279 
 
 Lloyd Dale's process 401 
 
 Logwood 113 
 
 ,, black 120 
 
 ,, dyeing with 119 
 
 „ extract 1 19 
 
 ,, preparation of for dye- 
 ing 118 
 
 ,, purple 120 
 
 Lokaetin 304 
 
 Lokain 302 
 
 Lo-kao 301 
 
 ,, dyeing with... 304 
 
 Loose colours 19 
 
 Luteolin 277 
 
 MACHROMIN 265 
 
 Maclura tinctoria ... 262 
 
 Maclurin 264 
 
 Page. 
 
 Madder 22 
 
 ,, adulteration of 104 
 
 ,, alcohol from 89 
 
 ,, changed by keeping 26 
 
 ,, colours on cloth 107 
 
 , , composition of 24 
 
 11 dyeing 81 
 
 ,, ,, clearing 83 
 
 ,, „ soaping S3 
 
 ,, ,, use of chalk in, 27, 8 1 
 ,, extract, recipes for dye- 
 ing with 96 
 
 , , extracts of 90 
 
 ,, flowers of 89 
 
 „ injured by keeping 89 
 
 ,, lake 103 
 
 ,, manufacture of 23 
 
 „ sugar from 35 
 
 ,, testing 105 
 
 ,, use of 64 
 
 Magdala red 478 
 
 Magenta 363 
 
 ,, adulteration of 379 
 
 ,, discoveiy of 364 
 
 ,, dyeing with 374, 377 
 
 ,, manufacture of... 365, 373 
 
 „ printingwith ... 377, 378 
 
 ,, purification of 367 
 
 Manchester yellow 472 
 
 Manganese mordant for aniline 
 
 black 439 
 
 Manufacture of aniline 356 
 
 ,, Bleu de Lyon ... 403 
 
 ,, garancin 84 
 
 ,, indigo 141 
 
 ,, madder 23 
 
 „ magenta... 365, 373 
 
 „ mauve 385, 388 
 
 „ nitrobenzene ... 355 
 
 ,, orchil 229 
 
 ,, rosaniline 371 
 
 Maroons, aniline 432 
 
 Martius' yellow 472 
 
 Mauve, discovery of 384 
 
 ,, manufacture of 385, 388 
 
 ,, purification of 385 
 
 Mauvaniline 367, 392 
 
 Mauveine 386 
 
 Melin 274 
 
 Menispermum fenestration 293 
 
 Mesteque 208 
 
 Meta-amidobenzoic acid 167 
 
 Metagallic acid 312, 317 
 
 Metanitrotoluene 361 
 
 Metatoluidine 362 
 
 Methyl green 422 
 
 ,, salicylate 163 
 
 Methylaniline 397, 398 
 
 m green 422 
 
INDEX. 
 
 505 
 
 Page. 
 
 Methylorcin 238 
 
 Methylrosanilines 393 
 
 Mimotannic acid 333 
 
 Mimotanninhydroetin 336 
 
 Mock Turkey red 131 
 
 Mononitro-orcin 237 
 
 Monophenylrosaniline 390 
 
 Monoxyanthraquinone 46 
 
 Mordant, black 75 
 
 ,, dark chocolate 75 
 
 ,, ,, purple 73 
 
 „ „ red... 74 
 
 ,, light chocolate 75 
 
 „ ,, purple 73 
 
 ii ,, red 74 
 
 Mordanting Turkey red 67 
 
 Mordants, examination of 348 
 
 ,, printing machine for 76 
 
 ,, theory of 17 
 
 ,, Thorn's experiments 
 
 on 17 
 
 Moric acid 264, 266 
 
 Morin 266 
 
 ,, blanc 263 
 
 ,, jaune 263 
 
 ,, relation of to rhamnetin ... 273 
 
 Morinda citrifolia 1 1 1 
 
 Morindin m 
 
 Molindone in 
 
 Morintannic acid 264 
 
 /Moras tinctoria 262 
 
 Munjeet 106, 108 
 
 ,, garancin 109 
 
 Mungistin 109 
 
 Murexide 225, 457 
 
 Myrobalans 328 
 
 NAPHTHA, coal-tar 352 
 
 Naphthalene 470 
 
 ,, colours 470 
 
 Naphthalenesulphonic acid 471 
 
 Naphthazarin 55 
 
 Naphthol 471 
 
 Naphthylamine 475 
 
 red 478 
 
 violet 480 
 
 Naphthylpurpuric acid 473 
 
 Natal aloes 279 
 
 Natalo'in 281 
 
 Nature of aniline black 442 
 
 , , colouring matters 3 
 
 Neb-neb 327 
 
 Nicholson's blue 407 
 
 Night blue 404 
 
 Nigraniline 444 
 
 Nitrindin 161 
 
 Nitroacetophenone 1 69 
 
 Nitroalizarin 41 
 
 Nitrobenzene 354 
 
 Page. 
 
 Nitrobenzene, manufacture of ... 355 
 
 N itrococcusic acid 213 
 
 Nitrocinnamic acid 172 
 
 Nitroerythrite 244 
 
 Nitro-orcins 236, 237 
 
 Nitronaphthalene 476 
 
 Nitronaphthalic acid 475 
 
 Nitrophloroglucin 259 
 
 Nitropurpurin 41 
 
 Nitrosalicylic acid 162 
 
 Nitrotoluenes 360 
 
 Nopal 206 
 
 Nucitannin 329 
 
 OAK bark 328 
 
 CEnolin 135 
 
 Oil, Gallipoli 70 
 
 ,, of wintergreen 163 
 
 Oiling Turkey red 66 
 
 Old fustic 263 
 
 ,, dyeing with 268 
 
 , , reactions of 263 
 
 Optical characters of alizarin ... 62 
 
 , , , , purpurin . . 60 
 
 Orange extract of madder 94 
 
 Orcein 237 
 
 Orchil 228 
 
 , , manufacture of 229 
 
 ,, uses of 233 
 
 Orcin 234 
 
 Orellin 290 
 
 Orsellesic acid 246 
 
 Orsellic acid 241, 243 
 
 Orsellinic acid 246 
 
 Orthonitrotoluene 361 
 
 Orthotoluidine 362 
 
 Oxalic acid from garancin wash- 
 ings 86 
 
 Oxindicanin 157 
 
 Oxindol 171 
 
 Oxynaphthalic acid 56 
 
 Oxyphenic acid 336 
 
 Oxytoluic acid 360 
 
 PALUDS 24 
 
 Paracarthamin 299 
 
 Paracoumaric acid 282 
 
 Paradatiscetin 257, 258 
 
 Paraf's extract of madder 92 
 
 Paranitrotoluene 360 
 
 Paraoxybenzoic acid 282 
 
 Pararosaniline 374 
 
 Paratoluidine 362 
 
 Parellic acid 247 
 
 Paris violet 397 
 
 Parmdia parietina 296 
 
 Pastel 143 
 
 Peach wood 121 
 
 Pectic extract 94 
 
506 
 
 INDEX. 
 
 Page. 
 
 Peonine 462 
 
 Perchlorquinone 166 
 
 Perkin's green 422 
 
 Pernambuco wood 121 
 
 Pernod's extract of madder 95 
 
 Persian berries 270 
 
 dyeing with 274 
 
 ,, ,, reactions of 270 
 
 Phenicienne 468 
 
 Phenol 450 
 
 Phenyl carbamic acid 167 i 
 
 Phenyl violets 391 ' 
 
 Phloramine 259 
 
 Phloroglucin 257, 259, 264 i 
 
 Phcenicine 387 j 
 
 Phosphine 425 
 
 Phyllocyanin 307 
 
 Phylloxanthin 307 
 
 Picramic acid 456 
 
 Picric acid 163,452 | 
 
 Picrocyamic acid 456 
 
 Pi croery thrin 240, 242, 246 ! 
 
 Pincoffine 88 
 
 Pipe gamboge 294 
 
 Podophyllum pdtatum 294 
 
 Podyophyllum root 294 
 
 Pollution of rivers 85 
 
 Polygonium fagopynun 296 
 
 ,, tinctorium 144 
 
 Pomona paste 424 
 
 Ponceau 382 
 
 Potassium isopurpurate 45 7 
 
 Preparation of cochineal 208 
 
 »> >> logwood for dyeing 1 18 
 
 ,, ,, woad 143 
 
 Printing calico 72 
 
 ,, chlorophyll 309 
 
 ,, indigo 185 
 
 ,, machine for mordants .. 76 
 
 ,, Turkey red 71 
 
 ,, with artificial alizarin... 100 
 
 „ magenta 377, 378 
 
 ,, ,, safranine 381 
 
 Process of Lloyd Dale 401 
 
 Properties of indigotin 158 
 
 Protocatechuic acid . . . 258, 264, 335 
 
 Protococcus vulgaris 244 
 
 Pseudo-corallin 465 
 
 Pseudo-curcumin 286 
 
 Pseudo-erythrin (ethylic orselli- 
 
 nate) 240 
 
 Pseudo-orcin (erythrite) 243 
 
 Pseudo-purpurin 36, 38 
 
 Pterocarpus marsupium 330 
 
 ,, santalinus 128 
 
 Pulverising indigo 198 
 
 Pure indigotin 158 
 
 Purification of indigo 1S8 
 
 „ magenta 367 
 
 Page. 
 
 Purification of mauve 385 
 
 Purple assistant liquor 73 
 
 ,, logwood 120 
 
 ,, mordant dark 73 
 
 ,, light 73 
 
 ,, Regina 391 
 
 Purpurin 38, 58, no 
 
 hydrate 37 
 
 ,, hydride of 59 
 
 ,, detection of 63 
 
 ,, Kopp's 92 
 
 , , optical characters of 60 
 
 Purpurinamide 58 
 
 Purpurolein 1 34 
 
 Purpuroxanthin 37, 38 
 
 Purree 297 
 
 Pyrocatechin 336 
 
 Pyrocatechuic acid 336 
 
 Pyrogallic acid 316 
 
 Pyrogallol 316 
 
 QUERCETIC ACID 257, 258 
 
 Quercetin 255, 259 
 
 Quercimeric acid 258 
 
 Quercitannic acid 255, 328 
 
 Quercitrin 255 
 
 Quercitron 253 
 
 ,, dyeing with 261 
 
 ,, reactions of 254 
 
 Quercus agylops 324 
 
 ,, infectoria 321 
 
 nigra 253 
 
 ,, robur... 323 
 
 „ tinctoria 253 
 
 REACTIONS of annatto 289 
 
 ,, barwood 132 
 
 , , brazil wood ex- 
 tract 125 
 
 ,, catechu 332 
 
 ,, cochineal 213 
 
 „ hematoxylin... 117 
 
 ,, old fustic 263 
 
 ,, Persian berries 270 
 
 ,, quercitron 254 
 
 ,, sandal wood... 132 
 
 ,, sumach 352 
 
 ,, weld 276 
 
 , , young fustic . . . 269 
 
 Recipes for dyeing with madder 
 
 extract 96 
 
 Recovery of waste colour ...101, 102 
 
 „ ,, indigo 197 
 
 Red Adrianople 64 
 
 ,, corallin 462 
 
 , , dyewoods 113 
 
 ,, Magdala 478 
 
 ,, mordantdark 74 
 
 „ „ light 74 
 
INDEX. 
 
 507 
 
 Page. 
 
 Red naphthylamine 47& 
 
 ,, Turkey 64 
 
 „ ,, printing 71 
 
 Reduction of indigo by hyposul- 
 phites 184 
 
 Regianic acid 3 2 9 
 
 Regianin 3 2 9 
 
 Regina purple 39 1 
 
 Relation of morin and rhamnetin 273 
 
 Reseda luteola 276 
 
 Reserve process (indigo) 200 
 
 Resist process , , 200 
 
 Resorcin . 249 
 
 , , from sapan wood 123 
 
 ,, indophane 473 
 
 Rhamnagin 272 
 
 Rhamnetin 272 
 
 , , relation to morin 273 
 
 Rhamnin 273 
 
 R/iaiii mis cathartkus 302, 305 
 
 Rheum 298 
 
 Rhotic acid 3 2 9 
 
 Rhubarb 298 
 
 Rhus coriaria 3 2 4 
 
 ,, cotinus 268 
 
 ,, semialata 3 2 4 
 
 Rivers, pollution of 85 
 
 Robinin 256 
 
 Roccella fuciform is 229, 239 
 
 ,, tinctoria 229, 241, 247 
 
 Roccellic acid 247 
 
 Roccellinin 247 
 
 Rosanaphthylamine 478 
 
 Rosaniline 368 
 
 „ acetate 369* 37 1 
 
 ,, formation of 359 
 
 ,, hydrochloride 369 
 
 ,, manufacture of 371 
 
 ,, picrate 369 
 
 Rose colour, brazil wood 127 
 
 Rosees 24 
 
 Roseine 37 l 
 
 Rosocyanin 287 
 
 Rosolic acid 458 
 
 Rosotoluidine 373 
 
 Rothine 468 
 
 Rottlera tinctoria 301 
 
 Rottlerin 281, 301 
 
 Ruberythric acid 35 
 
 Rubiacic acid 3°» 33 
 
 Rubiacin 33> 34 
 
 ,, injurious effect of 81 
 
 Rubiadin 3°> 33 
 
 Rubiafin 3°> 33 
 
 Rubiagin 3 l 
 
 Rubian 24, 28 
 
 ,, decomposition of 29 
 
 Rubianic acid 36 
 
 Rubianin 3°> 33 
 
 Page. 
 
 Rubichloric acid 29 
 
 Rubinic acid 335 
 
 Rubiretin 30, 33 
 
 Rulicoccin 213 
 
 Rufigallic acid 315 
 
 Rufimoric acid 265 
 
 Rufitannic acid 313 
 
 Rumex obtusifolius 298 
 
 Runge's blue 388 
 
 Rutin 274, 298 
 
 Safflower 135 
 
 ,, composition of 136 
 
 ,, dyeing with 138 
 
 ,, yellow colouring matter 
 
 from 138 
 
 Saffron 292 
 
 Saffronin (from saffron) 292 
 
 Safranine or saffranine 380 
 
 ,, hydrochloride 380 
 
 ,, printing with 381 
 
 Salicylic acid 163 
 
 Salts, effects of on colours 18 
 
 Sandalwood 128 
 
 ,, ,, reactions of 132 
 
 Sanders wood 128- 
 
 Santa Martha wood 121 
 
 Santal 130 
 
 Santal wood 128 
 
 Santalic acid 129 
 
 Santalin . 129, 130 
 
 Sap green 305 
 
 Sapan wood 122 
 
 Sappanin 123 
 
 Saxony blue 178 
 
 Scarlet, Ulrich's 383 
 
 Schiitzenberger's and Lalande's 
 
 process 184 
 
 Scoparin 299 
 
 Seeddac 223 
 
 Sesam oil 1 1 1 
 
 Shelblac 224 
 
 ,, composition of 224 
 
 Soap waste, utilisation of 103 
 
 Soaping madder dyed goods ... 83 
 
 Socalo'in 281 
 
 Socotrin aloes 279 
 
 Soluble green 420 
 
 Sooranjee Ill 
 
 Sophora japonica 299, 304 
 
 Sorgho 133 
 
 ,, carmine 134 
 
 ,, red 134 
 
 Sorghum saccharatum 133 
 
 Spaniolitmin 248 
 
 Spartium scoparium 299 
 
 Spectroscopic examination of 
 
 colours 34^ 
 
 Spectrum 2 
 
508 
 
 INDEX. 
 
 Page. 
 
 Spruce bark 328 
 
 Stick-lac 222 
 
 ,, composition of 222 
 
 Styphnic acid 123 
 
 Sugar from madder 35 
 
 ,, cane, Chinese 133 
 
 Sulphindigotic acid 176 
 
 Sulphisatyde 161 
 
 Sulphoflavic acid 181 
 
 Sulphonaphthalic acid 471 
 
 Sulphopurpuric acid 175, 181 
 
 Sulphorufic acid 181 
 
 Sulphoviridic acid 180 
 
 Sulphurous acid, bleaching ac- 
 tion of 16 
 
 Sumach 324 
 
 ,, dyeing with 326 
 
 ,, reactions of 325 
 
 , , uses of 326 
 
 Synthesis of indigo 1 69, 173 
 
 TAIGU wood 300 
 
 Taiguic acid 300 
 
 Tannic acid 31 1 
 
 Tannin, estimation of 338 
 
 ,, matters 310 
 
 Tannins 310 
 
 Tannoxylic acid 313 
 
 Tayegu wood 300 
 
 Tein-hoa-tein-ching 144 
 
 Terminalia chcbula 328 
 
 Terra firma wood 122 
 
 Terra japonica 330 
 
 Testing cochineal 215 
 
 ,, indigo 191 
 
 , , lichens 233 
 
 ,, madder 105 
 
 Theory of mordants 17 
 
 Thorn's experiments on mordants 1 7 
 
 Tetrabromonuoresce'in 251 
 
 Tetranitroerythrite 244 
 
 Tetrazoresorcin 251 
 
 Tetrazoresorufin 251 
 
 Toluene 359 
 
 Toluidine, blue 408 
 
 ,, _ red 373 
 
 Toluidines 362 
 
 Tournesol en drapeaux 249 
 
 Transformation of iodine green 421 
 
 Triamylorcin 239 
 
 Tribromomoric acid 266 
 
 Trichloraniline 1 64 
 
 Trichlorophenol 1 64 
 
 Triethylorcin 239 
 
 Triethylrosaniline 393 
 
 Trimethylchrysotoluidine 429 
 
 Trimethylorcin 239 
 
 Trimethylrosaniline, dimethyl- 
 iodide of 416, 421 
 
 Page. 
 
 Trini tro-orcin 236 
 
 Trinitrophenol 452 
 
 Trinitroresorcin 123 
 
 Triphenylrosaniline 404 
 
 Triphenylrosanilinesulphonic 
 
 acid 417 
 
 Turkey red 64 
 
 ,, clearing 68 
 
 ,, dyeing 67 
 
 ,, mock 131 
 
 ,, mordanting 67 
 
 , , oiling 66 
 
 ,, print 71 
 
 Turmeric 284 
 
 ,, dyeing with 287 
 
 ,, composition of 285 
 
 Tyrosine 210 
 
 ULRICH'S scarlet 383 
 
 L T ncaria gambir 330 
 
 Uric acid 225 
 
 Urine, indigo from 205 
 
 Use of chalk in madder dyeing.. 81 
 
 ,, madder 64 
 
 Uses of annatto 291 
 
 1, orchil 233 
 
 ,, sumach 326 
 
 L ~s>ica florida 244 
 
 Usnic acid 244 
 
 Utilisation of soap waste 103 
 
 VALONIA 324 
 
 Variolaria dcalbata 229 
 
 , , orcina 229, 240 
 
 Vat, Cohen's (indigo) 199 
 
 ,, cold (indigo) 197 
 
 ,, Indian (indigo) 203 
 
 ,, Leuch's (indigo) 204 
 
 ,, woad 203 
 
 Venetian lake 128 
 
 Verantin 30, 32 
 
 Vert- Azof 301 
 
 ,, lumiere 301 
 
 ,, Venus 301 
 
 Victoria yellow 469 
 
 Violaniline 367, 392 
 
 Violet, aldehyde 400 
 
 ,, Britannia 400 
 
 ,, Dorothea 398 
 
 ,, ethyldiphenylamine 399 
 
 ,, Imperial 390 
 
 ,, Kopp's 392 
 
 , , naphthylamine 480 
 
 n Paris 397 
 
 ,, Wanklyn's 400 
 
 Violets, aniline 384 
 
 ,, benzylic 399 
 
 ,, Hofmann 393 
 
 „ Phenyl 391 
 
INDEX. 
 
 509 
 
 Page. 
 Vulpicacid 296, 297 
 
 WAIFA •••274, 299, 304 
 
 Wall lichen 296 
 
 Walnut husks 3 2 9 
 
 Wanklyn's violet 400 
 
 Waste colour, recovery of...ioi, 102 
 
 ,, indigo, recovery of 197 
 
 , , utilisation of soap 1 03 
 
 Weld 276 
 
 ,, dyeing with 278 
 
 ,, reactions of 276 
 
 White indigo 182 
 
 ,, light, analysis of 2 
 
 Woad 143. x 46 
 
 ,, preparation of 143 
 
 „ vat 203 
 
 Wongshy 3 QI 
 
 Wintergreen oil 163 
 
 XANTHEIN 9 
 
 Xanthin 25, 28, 29 
 
 ,, of flowers 8 
 
 Xantholein 134 
 
 Xanthorhammin 271, 272 
 
 Xylidine red 374 
 
 Page. 
 Xylochloeric acid 309 
 
 YELLOW, adulteration of ani- 
 line 431 
 
 ,, alizarin 93 
 
 bark. 293 
 
 ,, Campo Bello 469 
 
 ,, colouring matter 
 
 from flowers ... 138 
 
 ,, corallin 466 
 
 Dutch 275 
 
 Fol's 46S 
 
 ,, Indian 297 
 
 ,, Jacobsen's 431 
 
 ,, Manchester 472 
 
 ,, Martius' 472 
 
 ,, Victoria 469 
 
 ,, wood 263 
 
 Yellows, aniline 425 
 
 Young fustic 26S 
 
 ,, reactions of 269 
 
 ZACATILLA 208 
 
 Zanzibar aloes 279 
 
 Zinaline 43° 
 
 Palmer and Howe, Printers by Steam Pa:oer, 1, j>, d-= J, Bond-Si., Manchester. 
 
ERRATA. 
 
 Page 24, line 9, for 'palus,' read 'palud.' 
 
 , 88, 
 
 , 127, 
 
 , 166, , 
 
 , 166, , 
 
 , 227, , 
 
 , 229, , 
 
 , 236, , 
 
 > 294, , 
 
 , 3 0I > > 
 
 , 45 6 > . 
 
 11, „ 'or clearing,' read 'but only clearing.' 
 9, „ 'M. K. Koechlin,' read 'M. H. Koechlin.' 
 30, „ 'Bromisatinic acid,' read 'Bromisatic acid.' 
 32, „ ' Dibromisatinic acid,' read 'Dibromisatic 
 
 acid.' 
 10, „ poupre] read pourpre? 
 17, „ 'Leconaria,' read 'Zemnora.' 
 13-14,,, 'monobromicin,' read 'monobromorcin.' 
 15, „ '/lydroberberin,' read ' hydroberberine? 
 27, „ ' Vert-Iumiere,' read ' Vert-lu/niere.' 
 6, „ '2 OH,' read '2OH,'. 
 
JUST PUBLISHED, 
 
 In Two Handsome Quarto Volumes, strongly Bound, containing 40 Plates, 
 and 259 other Illustrations. 
 
 Price £4 4s. 
 THE SCIENCE OF 
 
 MODERN COTTON SPINNING. 
 
 BY 
 
 EVAN LEIGH, C.E, 
 
 Palmer & Howe, PtiMishers, 1, 3, and 5, Bond Street, Manchester. 
 SimpMn, Marshall, &• Co., London. 
 
 OPINIONS OP THE PRESS. 
 
 [ From the Manchester Examiner and Times. ] 
 
 Cotton spinning is not often honoured by being the subject of such handsome 
 volumes as these, but Mr. Leigh evidently thought the history of cotton, from 
 its growth in America or India to its appearance as twist, was not only worthy 
 of a detailed record, but of a work in which neither the engraver's nor the 
 printer's art should leave anything to be desired. Accordingly we have two 
 folio volumes which rival in appearance most of the illustrated gift books of the 
 season, printed on fine paper, and illustrated by a considerable number of 
 engravings. 
 
 But if the first sight of the work should suggest the idea of its purpose being 
 merely to provide scientific entertainment for the drawing room, the impression 
 would be erroneous ; the work is essentially practical, and though a knowledge 
 of cotton spinning is not often acquired by the study of books, we may add that 
 Mr. Leigh's book is pre-eminently didactic. The first edition, indeed, was so 
 successful that, we understand, arrangements have already been made for 
 translations of the book into several foreign languages. 
 
 Throughout the book, as we stated above, Mr. Leigh is very practical, and his 
 advice is the result of considerable personal experience during nearly half a 
 century. But we will leave others better acquainted with the subject to say how 
 far he is justified in making the inferential promise in the following passage from 
 the preface : — " The author dwells but little on present examples, which may be 
 seen in every day operation, but rather points to the inevitable future, taking 
 care to advise no step but what is both safe and practical, and by which large 
 sums of money may be saved in original outlay, and consequently in cost of 
 production." But many spinners who are at a loss for advice when about to 
 make changes in machinery, &c, may turn with advantage to Mr. Leigh's book 
 as an impartial guide, the object of which is to counsel real economy, and to give 
 recommendations without favour. 
 
 In a work of this character the author, of course, trusts very much to the 
 assistance of his engraver, and Mr. Leigh in this respect is extremely fortunate. 
 The engravings tell their own story,. and, so far as this department is concerned, 
 the book is almost exhaustive. 
 
OPINIONS OF THE PRESS.— Continued. 
 
 [From the Manchester Guardian.] 
 
 These handsome volumes mark a decided advance upon anything in the 
 literature of cotton spinning which, so far as our acquaintance goes, has yet been 
 published in this country. The author, who has had nearly half a century's 
 extended and active experience in the business, ought certainly to have some- 
 thing to say worth the attention of all who have more recently entered it, and 
 even of others who, though not inexperienced, have had a few opportunities of 
 wide observation. A book of this kind has, in fact, for some time bark been 
 wonted. Most of those previously extant are out of date, and little has been 
 hitherto done toward collecting together the scattered results of improvements in 
 machinery and in methods of management which little by little have wrought on 
 the whole no inconsiderable changes in the operations of cotton spinning. 
 
 The first part of the book supplies a very full description of the principal 
 varieties of cotton, together with a statistical account of their production. Then 
 comes a chapter on mill architecture, which includes some lengthened observa- 
 tions upon building materials. On the cpiestion of "belting versus mill gearing" 
 English spinners will scarcely be at first sight disposed to side with Mr. Leigh in 
 his decided preference for belting. Yet this plan appears to be almost 
 universally adopted in America. There certainly appears much to be said in 
 its favour, and perhaps the high cost of iron now prevailing may lead to a trial 
 of the system in this country ere long. 
 
 Some pages on steam engines complete what may be called the introductory 
 part of the work, and we now enter upon the earlier stages of the process of 
 cotton spinning proper — viz., mixing, opening, and scutching. Besides the 
 older forms of openers and scutchers, the more recent ones of Crighton and Lord 
 are very fairly described. On the subject of carding Mr. Leigh gives his 
 opinion at once in favour of "flats" as against rollers. 
 
 In connection with this subject we have also much very valuable information 
 respecting the choice and management of cards. Some pages are devoted to the 
 combing machine, not only the beautiful and well-known invention of Heilmann, 
 but also a more recent discovery of Joseph Imbs, who, like the late M. Heilmann, 
 is a native of France. In the remarks on slubbing, intermediate and roving 
 frames we have much useful practical advice respecting the adjustment of 
 draughts and the management of these preparatory processes. 
 
 Passing on now to the chapters on spinning, we have, after a judiciously slight 
 historical sketch, a full and interesting account of the throstle frame in all its 
 varieties. Mule spinning receives equally full treatment, and then follow very 
 useful directions for doubling, gassing, polishing, and spooling. 
 
 The illustrations are abundant, and the mechanical drawing is very well done. 
 We repeat, in conclusion, our opinion that this is the best work on the subject 
 of cottou spinning that has yet appeared in this country. 
 
 [From the Manchester Courier.] 
 
 An examination of the two handsome volumes before us will show that the 
 promise of the title, lengthy though it be, is more than fulfilled. The articles 
 are most elaborate, and most carefully written, while so far as we can discover 
 the most perfect impartiality is exhibited with reference to the machinery 
 described. The introductory chapter describes the varieties of the cotton plant 
 and illustrates most completely the length of staple of the different kinds by 
 means of illustrations of full size laid out on a scale of tenths of an inch Then 
 comes a chapter on cotton mill architecture, with an account of the great " India 
 Mill" at Over Darwen, the architect's plans, sections, and elevations of which 
 are fully giveu. 
 
 The remaining chapters will be found equally useful and equally practical, and 
 if Mr. Leigh's work as a whole cannot pretend to any special graces of style or 
 remarkable literary merit, it may at least be said that he has brought to his task 
 great practical knowledge and abundant common sense. 
 
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