Dr. Hofmann on the Metamorphoses of Indigo. 395 



In their relation to other bodies, both compounds also agree, 

 but to a more limited extent. The intense yellow colour 

 given to pine-wood and the pith of the elder tree by acid so* 

 lutions of aniline, is also produced by the salts of the chlori- 

 nated compound. On the other hand, the characteristic violet 

 colour communicated to aniline by chloride of lime, is not ex- 

 hibited by the compound derived from it; a solution of this 

 reagent by mixture with this body assuming only a slight 

 shade of violet. ^ The solution of the salts takes the same co* 

 lour, which however rapidly passes into orange. Neither is a 

 cold or hot watery solution of the base nor of its salts altered 

 by chromic acid, whilst aniline under the same circumstances 

 gives rise to dark or greenish-blue products. On adding 

 chromic acid to the crystals of the chlorinated base, they be- 

 come brown and i-esinify. A mixture of these crystals with 

 solid chromic acid inflames at the fusing-point of the base. 



With regard to its relation to other reagents, I have to 

 remark the following: — Peroxide of iron is not precipitated 

 by the watery or alcoholic solution of the base. In both cases 

 the fluid becomes green, from a partial reduction of the per- 

 salt of iron. By employing a watery solution of the base or 

 crystals of it, a violet product of oxidation vseparates at the 

 boiling-point, which is soluble in alcohol. No change is pro- 

 duced in protosalts of iron, nor in sulphates of alumina or of 

 zinc, even by boiling them with the crystals. These oxides, 

 however, are precipitated by aniline, from which it is evident 

 that by the entrance of chlorine into its composition, its basic 

 properties are somewhat enfeebled. Sulphate of copper is 

 not precipitated by a watery solution of the base, but on add- 

 ing some of its crystals to a boiling copper solution, the latter 

 is immediately decolorized, and then deposits a mass of cry- 

 stals of a bronze colour, which are insoluble in water, but are 

 partially dissolved in boiling alcohol, from which on cooling 

 they crystallize in the form of scales. It appears to be a 

 double salt of sulphate of copper and of the chlorinated base. 

 Similar double salts are produced with the perchlorides of 

 mercury, platinum and palladium ; the first of these being 

 white, the latter two of a splendid orange-yellow colour. The 

 precipitate from a gold solution is reddish brown. Tincture 

 of galls is not changed by a cold solution of the base, but on 

 adding a hot saturated solution, a yellow flocky precipitate is 

 produced on cooling. Other chemical reagents are not af- 

 fected by its watery solution. 



c. Compounds of Chlor aniline. 

 The extraordinary facility of crystallizing which distin- 



