26 



ANILINE, OK COAL-1AE COLOES. 



in fact accompanies rosaniline in all the usual 

 modes of production, and can be obtained from 

 the residue that remains after the extraction of 

 the latter, by passing through it a current of 

 steam, condensing, and adding nitric acid. The 

 nitrate of the base is thus formed, and being 

 extremely insoluble in water, is at once pre- 

 cipitated. The base, isolated, is in form of a 

 yellow powder, and from its color the discoverer 

 named it chrysaniline. It is very soluble in al- 

 cohol and ether. Its composition is C^H^Ns ; 

 i. e., rosaniline 2 II. Again, rosaniline acted 

 on by nascent hydrogen (the dye being dissolved 

 in hydrochloric acid, and zinc added), gives rise 

 to a third base, and to this, as being perfectly 

 colorless both in itself and in its salts, Hofmaun 

 gave the name of leucaniline. Its composition 

 is C 4 oH 2 iN 3 ; i. e., rosaniline + 2 II. This sub- 

 stance, however, when long exposed to the air 

 becomes slightly red, and still more so when 

 heated. 



It long passed as a fact that the magenta or 

 crimson dye was a product of the oxidation of 

 the aniline proper contained in the impure ani- 

 line of commerce. More recently, however, 

 Hofmann tried upon pure aniline the usual re- 

 action, and found that the crimson dye could 

 not be obtained from it. As was natural, he 

 next tried pure toluidine, but still no rosaniline 

 was produced. But upon mixing the two ma- 

 terials, both pure, the reaction of a suitable 

 oxidizer at once gave the coloring matter. lie 

 infers that to the formation of rosaniline both 

 toluidine and aniline proper must contribute, a 

 portion of their hydrogen being meantime given 

 up to the oxygen of the reagent used : the re- 

 sult may be thus represented 2 (C J4 H 9 N) + 

 (C 12 H 7 N) 7 H = C 4 oH ia N3. Quite recently, 

 also, MM. Laurent and Casthelez have succeed- 

 ed in converting nitro-benzole by a single opera- 

 tion into aniline crimson. This they effect by 

 mixing the former with iron and hydrochloric 

 acid, or with protochloride of iron, and then 

 heating. At first, aniline and perchloride of 

 iron result ; and when the mixture is heated, 

 the perchloride reacts on the aniline, producing 

 rosaniline. 



Some of the facts here stated in relation to 

 rosaniline and the related substances were given 

 in the preceding volume of this CYCLOPAEDIA : 

 such are here repeated only so far as is requisite 

 to a sufficiently connected and clear view of the 

 entire subject. In the same place will be found 

 a brief account of the aniline ~blue, with a ref- 

 erence to the analogous colors in which the 

 phenyle-radical of that substance is replaced by 

 ethyle, methyle, and arnyle, respectively^ and 

 also to the cyanine, obtained from chinoline. 

 Aniline yields otner dyes than those yet named, 

 as the green, or emeraldine, &c. ; and several 

 dyes are in use which are procured from certain 

 other derivatives of coal-tar ; among the latter 

 being picric acid, and (it would appear) azuline, 

 &c. As might be expected, however, in the 

 beginning of a branch of industry of such ex- 

 tent, a considerable variety of usage and oven 



much confusion still exist among manufacturers 

 and dealers in reference to the very names of 

 the various colors obtained from coal-tar prod- 

 ucts. In such a state of things, a systematic 

 and complete classification of the new dyes is 

 as yet scarcely practicable. Some of the more 

 important of the coal-tar dyes, however, whether 

 yet practically in use or not so, require further 

 and special notice : of such a list is here given : 



1. Aniline purple (Perkiris purple, mauve, com- 

 mon aniline violet, ^mperial violet, penste, &c). 

 Obtained as a black precipitate, by mixing equiva- 

 lents of solutions of sulphate of aniline and bichro- 

 mate of potash, and allowing to stand; the precipitate 

 washed with water, and dried, digested in naphtha 

 till this ceases to be colored brown, then repeatedly 

 boiled in alcohol to extract the coloring matter; the 

 latter left upon distilling off the alcohol: thus pre- 

 pared it is not pure. When purified, and dried, it is 

 obtained as a brittle substance, having a beautiful 

 bronze-colored surface. As one test, a little of the 

 alcoholic solution being evaporated on a glass plate, 

 and viewed by transmitted light, appears of a beauti- 

 ful bluish-violet color. Many characteristic reactions 

 are given ; but of these, or those of the dyes yet to 

 be named, space does not here allow. The color 

 imparted by this dye is a bluish or deep violet. The 

 name mauve (French, for mallow,) was given from 

 a resemblance (supposed, at least) of the color to 

 that of the petals of the plant in question. It is 

 stated that much of the mauve now seen is an imita- 

 tion, with a dye obtained by a new process from 

 archil. While there are two unlike colors which 

 pass among dealers and dyers as solfcrino, one of 

 them is a purple or violet, of different shades, and is 

 stated to the writer to be identical with Perkin's 

 purple. 



2. Violine. A product of the oxidation of aniline, 

 first obtained by Dr. David Price, by means of the 

 action of binoxide of lead on a solution of two equiva- 

 lents of sulphuric acid and one of aniline in water. 

 Dried from alcoholic solution at the close of the pro- 

 cess (not here given in full), it resembles the aniline 

 purple dye, but has a more coppery appearance. 

 Very soluble in alcohol, insoluble in ether. 



3. Eoseine. First noticed by Mr. C. G. Williams, 

 afterwards by Dr. Price. The latter obtained it by 

 acting on a boiling solution of sulphate of aniline 

 with binoxide of lead, filtering, <fec. Dried, a dark, 

 brittle substance, of slightly metallic lustre ; dissolved 

 in alcohol, gives a fine crimson. The three coloring 

 matters thus far named are closelv allied. 



4. Aniline crimson (aniline red, aniline pink, ros- 

 aniline, magenta, fuclisine, roseine, &c). The history 

 of its discovery, as well as an account of its compo- 

 sition, has been given, and the sorts of reagents that 

 produce it from aniline have been named. Bechamp 

 considers the formula of anhydrous fuchsine as 

 CijHmNo, this, when the base is free, being associated 

 with H 2 0, giving C^H^J^O. Perkin, and after him 

 Dussauce, give quite fully the modes of preparing the 

 dye with bichloride of tin, and with nitrate^ of mer- 

 cury. As met with in commerce, the coloring mat- 

 ter, when not pulverized, is in small irregular masses 

 or lumps, having a golden-green semi-metallic lustre, 

 but which, in thin plates and by transmitted light, 

 are red. A light and sliglitly bluish magenta is the 

 other color to which the name of solfcrino is some- 

 times given. This, however, is not a proper violet 

 or purple, but a distinct and bright crimson. 



5. Chrysaniline (phosphine).As already stated, a 

 residual product, formed at the same time with 

 rosaniline, and removed from the residue left in pre- 

 parin"- that dye, by passing through it a current of 

 steam. It dyes a golden yellow, as its two names 

 from xpvaot;, gold, and phosphorus respectively in- 



6. Aniline Hue (Ueu de Paris lieu de Lvon, woJ 



