1862.] 3 



exhausting with water, a portion dissolves, while a more or less solid 

 resin remains behind. 



" The aqueous solution yields, on addition of potassa, an oily preci- 

 pitate containing a considerable portion of unchanged aniline ; on 

 boiling this precipitate with dilute potassa in a retort, the aniline 

 distils over, whilst a viscid oil remains behind, which gradually 

 solidifies with a crystalline structure. Washing with cold alcohol 

 and two or three crystallizations from boiling alcohol render this 

 body perfectly white and pure, a very soluble substance of a magni- 

 ficent crimson colour remaining in solution. 



" The portion of the black mass which is insoluble in water dis* 

 solves almost entirely in dilute hydrochloric acid, from which it is 

 reprecipitated by the alkalies in the form of an amorphous pink or 

 dingy precipitate soluble in alcohol with a rich crimson colour. The 

 greater portion of this body consists of the same colouring principle 

 which accompanies the white crystalline substance." 



The action of tetrachloride of carbon on aniline yields only a com- 

 paratively small quantity of the crimson pigment ; the temperature 

 of the exposure, and the relative proportions in which the two sub- 

 stances act upon one another, have the greatest influence upon the 

 results of the reaction. The white crystalline base, and the base 

 dissolving with a crimson colour, are by no means the only products ; 

 other bases, most of them amorphous and accessible only in the form 

 of platinum-salt?, are produced, and complicate, owing to the simi- 

 larity of their chemical characters, the purification of the new com- 

 pound. Notwithstanding many efforts, I failed in obtaining the 

 new colouring matter in a state fit for analysis, and for the time 

 abandoned the inquiry. 



Industry, however, was not long in discovering new and much 

 more appropriate methods for the production of the crimson aniline 

 dye. Certain metallic chlorides (tetrachloride of tin) and nitrates 

 (mercurous nitrate), and numerous oxidizing agents are capable of 

 converting aniline into the crimson colouring matter. It was M. 

 Verguin who first prepared this colour upon a large scale by the 

 action of tetrachloride of tin on aniline. Since that time the pro- 

 duction of the aniline-crimson has become an important industry, 

 which, in the hands of Messrs. Simpson, Maule, and Nicholson in 

 this country, of Messrs. Renard freres in France, has rapidly attained 



2 B 



