480 ' Br. A. W, Hofmann [April 11, 



who has succeeded in obtaining Magenta in a state of absolute purity. 

 Chemists have thus been enabled to analyze this substance, and to lift, 

 at all events, the corner of the veil which still covers the mysterious 

 formation of the coloured derivatives of aniline. 



In the pure state Magenta is a line crystalline, and, remarkably 

 enough, perfectly colourless, or only slightly tinted body, which is repre- 

 sented by the formula — 



Co H«i N3 = Co H,« N», H, O. 



Rosariiline (this is the name by which chemists designate the 

 colourless body) is a base, or ammonia-derivative, which forms a series 

 of splendid salts. With hydrochloric acid, for instance, it produces a 

 beautifully crystalline salt of the formula — 



C«»H,«N3,HC1. 



It is in the state of saline combination that rosaniline acts as a 

 crimson dye. Into this shallow porcelain dish I have thrown a few 

 crystals of rosaniline, which at a distance you scarcely perceive ; 

 I now pour upon these crystals a small quantity of acetic acid, 

 when on gently heating the dish the crimson colour instantaneously 

 appears. But it is only in solution that even the salts of rosaniline 

 are crimson-coloured ; on slowly evaporating their solution, the red 

 colour entirely vanishes, and a splendid green crystalline substance 

 remains, presenting in an extraordinary manner the beautiful metal- 

 lustre which distinguishes the wings of the rose-beetle. Together 

 with all the products involved in the manufacture of aniline and 

 aniline-dyes, my friend Mr. Nicholson has placed before you the finest 

 series of rosaniline-salts which has ever been produced ; and not con- 

 tent with this display, he was kind enough to send us a specimen of 

 acetate of rosaniline, such as no mortal eye has ever seen before. 

 The specimen may be literally called the Crown of Magenta.* Crowns 

 are always expensive articles, and often are the cost and trouble of 

 getting them greater than their actual value. This remark applies in 

 a measure to the Crown of Magenta. For the benefit of those who are 

 fond of big figures — and who is not a little afflicted with this weak- 

 ness? — I may state that the crown was grown in a vessel containing 

 not less than 8000/. worth of Magenta, the crown itself being worth 

 upwards of 100/. 



Having now explained the several stages of transition through 

 which coal has to pass before it becomes either Mauve or Magenta, it 

 may be of some interest to you to know the proportion which the 

 finished dye bears to the coal from which it is derived. A set of 

 specimen* for which I am likewise indebted to Mr. Nicholson, is most 

 instructive in this respect. Observe, it commences with a large mass 

 of coal, weighing not less than 100 lbs. ; the bottles which follow 

 contain the coal-tar-oil, naphtha, benzol, nitrobenzol, and aniline, 



* An immense aggregate of sparkling green octohedral crystals, — some of 

 them as much as an inch fn diameter, — deposited upon a large wire frame having 

 the shape of an elegant crown, was here exhibited. 



