28 



ANILINE, OR COAL-TAR COLORS. 



firmed by further experience that they are 

 aniline dyes. Evidently, if petroleum contains 

 benzole, identical with coal-tar benzole, or any 

 thing that for the color manufacture is equiva- 

 lent to this, or if it can largely yield aniline, 

 the fact will be one of great importance to the 

 future of American commerce and manufac- 

 tores. 



The colors obtained from aniline and other 

 coal-tar dyes are almost invariably distinguished 

 by a superior brilliancy, which is readily made 

 evident upon bringing into close proximity with 

 them similar hues furnished by other coloring 

 matters. The new dyes were, moreover, in the 

 outset, of extremely high price; and though re- 

 cently they have greatly declined, they are still 

 comparatively dear. For both these reasons, 

 the fabrics dyed with these colors have been, 

 and still are, held at a higher value on such ac- 

 count. Perkin's purple dye was for a long 

 time held at its weight in gold. In the London 

 Exhibition of 1862, Mr. Nicholson exhibited a 

 crown constructed of crystals of acetate of ros- 

 aniline, and which was valued at 100 sterling. 

 The writer is informed that at the present 

 time the imported dyes can be bought in New 

 York at prices of from $5 to $9 the pound,' in 

 gold. These coloring matters were, neverthe- 

 less, even when held at a much higher price, 

 available to the dyer, and chiefly for three rea- 

 sons: 1, their very high coloring power, so 

 that a little of the dye goes a great way ; 2, the 

 fact that the process of dyeing with them is 

 usually extremely simple ; 3, the higher price 

 the dyed fabrics would command. The power, 

 for example, of the mauve and magenta is shown 

 by the fact that T ' 5 th of a grain of either will 

 color substantially a gallon of alcohol. And 

 such has been the demand for the dyes, that, in 

 England at least, the production of Hofmann's 

 patent violet, obtained by action of the iodides 

 of ethyle, &c., on rosaniline, speedily occasioned 

 a considerable rise in the price of iodine. 



"Whatever may in the outset have been said 

 to the contrary, it is now well ascertained that 

 the coal-tar colors do not withstand the action 

 of light ; but that, as a rule, they lose their 

 brilliancy and fade even more readily than other 

 similar colors. In this respect, however, it is 

 already demonstrated that much depends on 

 the mode of preparing and applying the dyes ; 

 and some of these, in any case, produce much 

 more durable colors than others. M. Chevreul 

 and Mr. Perkin agree in pronouncing the hues 

 of magenta usually very fugitive, and most so 

 upon cotton. Aniline purple is said to resist 

 light among the best; and azuline, lieu de 

 Paris, and the yellow from picric acid, are also 

 very stable. 



When Mr. Perkin wrote, in 1861, only four 

 of all the dyes above enumerated were as yet 

 employed by the dyer and printer ; namely, ani- 

 line purple, aniline crimson, picric acid, and 

 azuline. It is evident that by the present time 

 vlie number has become greatly increased. A 

 i-encarkable quality in all the coal-tar dyes is 



their strong affinity for all manner of anima. 

 fibres (illustrated even in the tenacity of the 

 stain they leave on the fingers), and their in- 

 difference to vegetable fibrous materials. Thus, 

 they take effect most perfectly on silk and on 

 wool, and in these they exhibit their richest 

 hues. With these fabrics, as a rule, no mor- 

 dants are required, and very little, indeed, be- 

 yond thoroughly cleansing the silk or wool, 

 plunging it into a proper solution of the dye, 

 and then taking it out and washing : the dye is 

 so strongly attracted to the fibres, that it may 

 be said to become fixed in an instant ; while 

 some of the dyes, as aniline purple and violine, 

 are thus so completely withdrawn from the 

 liquid holding them in solution, that the latter 

 is speedily left colorless. In fact, with silk and 

 wool one great difficulty the dyer has to contend 

 with is the tendency of the fibres thus to be- 

 come dyed unevenly. 



The dyeing of silk with aniline purple, violine, 

 and roseine, is essentially effected by adding an 

 alcoholic solution of the dyes, diluted with hot 

 water acidulated with tartaric acid, to a dye- 

 bath of acidulated cold water, and working the 

 silk in this until of the required shade ; with 

 fuchsine, picric acid, chinoline blue, and violet, 

 still more simply, by working the silk in cold 

 aqueous solutions of the dyes, with the first two 

 especially avoiding acids ; with azuline, in the 

 color-solution acidulated with sulphuric acid, 

 first at a low, and then at a high temperature, 

 and afterwards carefully rinsing in water, work- 

 ing in soap lather, &c. The dyeing of wool with 

 any of these colors requires simply a dye-bath 

 consisting of a dilute aqueous color-solution, at 

 a temperature of about 40 F. In case, how- 

 ever, of linen, cotton, paper or other substances 

 of a vegetable nature, the dye may require to 

 be prepared with some material that shall play 

 the part of a mordant, as in Puller's and Per- 

 kin's process with tannin and stannate of soda, 

 or else the fabric may first be coated, or the 

 dye itself mixed, with some albuminous or ani- 

 mal matter, in order to secure action of the dye 

 on the fibre. It is stated, however, that fuchs- 

 ine, violine, roseine, and the chinoline colors 

 will act directly on vegetable fibres, while pic- 

 ric and rosolic acids are not applicable to the 

 dyeing of cotton. The tannin process, just 

 named, and also another in which a basic car- 

 bonate or oxide of lead is first formed on the 

 parts to be colored, and the fabric then worked 

 in the coloring solution, the color to be removed 

 by soap from the portions not mordanted, are 

 among the methods resorted to for printing 

 calicoes with coal-tar colors. 



When the dyeing of fabrics with the coal-tar 

 colors began to be practised, fears were enter- 

 tained that the health of the workmen would 

 suffer. Mr. Perkin states that during the few 

 years of his experience in the business, no sick- 

 ness had occurred among the workmen that 

 could be traced to the use of his own the ani- 

 line purple dye. In respect to working in ani- 

 line, the case would appear to be different. Dr. 



