INDIGO. 919 



of chlorisatin in alcohol; the liquid becomes colourless, and 

 sulphur is precipitated at the same time. Bichlorisatin in 

 similar circumstances yields bichlorisatyde, C 32 H 5 NC1 2 O 3 . 

 When treated with potash chlorisatyde and bichlorisatyde yield 

 chlorisatydic and bichlorisatydic acids. 



Chloranile, C 6 C1 2 O 2 , one of the products of the continued 

 action of chlorine upon chlorisatin and bi chlorisatin dissolved in 

 alcohol. It is a volatile substance in crystalline scales of a 

 brass yellow colour, which is dissolved by potash of a purple 

 colour, but is then converted into chloride of potassium and 

 chloranilate of potash. Chloranilic acid is a reddish powder, 

 composed of fine scales ; its composition is C 6 C1O 3 . 



Chrysanilic Acid, HO + C 28 H 10 N 2 O 5 . When indigo in pow- 

 der is added to a solution of caustic potash, of density 1.35, 

 and boiled in a silver vessel, an orange-yellow salt is formed, 

 without any evolution of gas. The acid is separated as a red- 

 dish-brown precipitate on the addition of sulphuric acid to a, 

 solution of the potash salt ; it is named chrysanilic acid, from 

 its relation to aniline and the golden-yellow colour of its salts. 

 (Fritsche). 



Anthranilic Acid, HO + C 14 H 6 NO 3 . The solution of the 

 fused mass above becomes blue in the air from absorption of 

 oxygen, like a solution of white indigo, and blue indigo pre- 

 cipitates in crystalline grains. On boiling the solution with 

 dilute sulphuric acid, the decomposition proceeds more rapidly, 

 and a brown resinous mass is obtained, soluble in alcohol, ether, 

 and alkalies. To prepare this acid, the first alkaline solution 

 is diluted, and peroxide of manganese added to it in small quan- 

 tities, at the boiling point, till the solution gives no black pre- 

 cipitate when rendered acid, and its colour is not reddish-brown 

 but a dirty greyish brown. This acid, when sublimed, is 

 white, and resembles benzoic acid, but the fused sublimate is 

 yellow. Its salt of lime is very soluble in hot water, and crys- 

 tallizes in colourless rhombohedrons. Anthranilic acid, distilled 

 by the heat of a spirit lamp, is decomposed in a considerable 

 measure, and resolved into carbonic acid and aniline. (Fritsche ; 

 Liebig, Annalen, &c., xxxix. 76 and 91.) 



Aniline, C 12 H 7 N (Fritsche) ; an oily liquid, which distils over 

 when finely pulverised indigo is decomposed by a highly concen- 

 trated solution of caustic potash or soda in a retort. Its quantity 



