Dr. Hofmann on the Metamorphoses of Indigo. 387 



large and important class of bodies. No organic base* is 

 knowji in which the hydrogen has been replaced by chlorine in 

 the aboxm-mentioned manner. And yet it would be an argu- 

 ment of the greatest weight, were chlorine, an electro-negative 

 element, to be introduced into a compound possessing electro- 

 positive properties, without however changing its chemical 

 character. 



The above considerations induced me to undertake the fol- 

 lowing research. 



The action of chemical agents in general upon the organic 

 bases has been as yet but little studied. For the first accu- 

 rate account of the special action of chlorine and bromine on 

 these bodies, we are indebted to Pelletierf, who investigated 

 the behaviour of strychnine toward chlorine, and at the same 

 time communicated some details on the influence exercised by 

 this body on quinine, cinchonine, brucine, morphine and 

 narcotine. From his experiments he ascertained that chlo- 

 rine withdrew from these bases hydrogen in the form of hy- 

 drochloric acid, and gave rise to neutral compounds difficult 

 of solution in water, but soluble in alcohol. On submitting 

 the crystalline product obtained from strychnine to analysis, 

 the presence of chlorine in its composition was ascertained. 

 Of the other bases, only quinine and cinchonine offered pro- 

 ducts of a somewhat crystalline structure. The physical pro- 

 perties of these substances however rendered their analysis so 

 difficult, that we are still in the dark as to the relation which 

 exists between them and the original compounds. 



Lately Brande and Leben % made some experiments on 

 the action of chlorine on quinine, and described the various 

 products — dalleiochine, rusiochine and melanochine, which 

 all contain nitrogen but no chlorine. The properties of 

 these bodies are not however well-defined, nor do their anar- 

 lyses bear the stamp of exactness, so that science has gained 

 but little by their investigation. The same may be said of the 

 researches of M. Andre § on the same subject. 



All these details relate to solid crystalline bodies. As to 



• By organic base, in the strict sense of the word, I understand here, 

 with Liebig. that class of compound, azotized bodies, which possess all the 

 properties of basic metallic oxides. The oxides of ethyle, methyle, &c., 

 are not included, as the most common character of salts is wanting in 

 their compounds, viz. the replacement of their acids by other acids, and 

 their bases by other bases, 



t Journal de Pharmacie, Avr. 1838, and Liebig's Jnn., Bd. xxix. S. 48. 



I Archiv der Pharmacie, Bd. xvi. S. 257, and Liebig's Ann., Bd. xxxii. 

 S. 270. 



§ Ann.de Chem. ct de Phys., t. Ixxi. p. 195, and Liebig's Ann., Bd. 

 xxxii. S. 273. 



2D 2 



