

FOBMATION OF INDIGO-BIXE. 225 



b Indifulvine. Indigo-blue. 



C« H 19 N a 3 = 2 Qe H, NO, + C lt H I3 3 — 3 H 



Indiretinc. Indigo-blue. Acetic acid. Propionic acid. 



C M H 17 NO l0 = C 16 H 4 N0 3 + 2 C 4 H 4 4 + 2 C.H, 0< — 8 H O 



It must not for a moment be supposed that these bodies 

 really are compounds of indigo-blue, or that the latter is in 

 any shape contained in them or may be obtained by their 

 decomposition. Indeed all my experiments lead to the con- 

 on that the elements are arranged in a manner very dif- 

 ferent from what might be inferred from the above equations. 

 If the nitrogenous substances formed from indican together 

 with indigo-blue were copulated bodies containing the latter, 

 it would be possible to obtain from them either indigo-blue 

 itself or its products of decomposition. With the small quan- 

 tities of these substances which were at my disposal I was 

 unable to make many experiments to decide this point. A 

 tolerably large quantity of indifuscine was however subjected 

 to the action of a strong caustic soda lye, the liquid being 

 boiled until it left a thick mass which was heated still further, 

 a small portion of it no longer dissolved in water with a 

 dark brown colour. I was unable however to discover among 

 the products of decomposition a trace of anthranilic acid, 

 which would probably have been present, if indifuscine con- 

 tained the elements of inctigo-blue. 



Some advantage may nevertheless arise from looking at 

 these compounds from the point of view just presented, as their 

 relation to one another, to indigo-blue and to indican is thereby 

 more vividly impressed on the memory. This method of con- 

 sidering them may also serve to show that these compounds 

 are all produced at the expense of indigo-blue, that the ele- 

 - contained in indican which have formed a certain portion 

 of indifulvine, indihumine, &c, might under certain unknown 

 circumstances have produced equivalent quantities of indigo- 

 blue, and that the latter cannot therefore be said in any sense 

 to pre-exist in indican. 

 2G 



