Dr. Schunck on the Formation of Indigo-blue. 133 



or more equivalents of water must be supposed to be eliminated, 

 as will be seen by a glance at the following equations : — 

 Indihumine. Indigo-blue. Acetic acid. 



C20H9 NO"' = C'«H^N02 + C H^ 0" 



Indifuscone. Indigo-blue. Pro])ionic acid. 



H22H10N05 = C'^H^NO^ -f C« H" O^-HO 



Indifuscine. Indigo-blue. Propionic acid. 



C24H10NO9 = C'^^H^NO^ -f C^ H6 04-f2C02-HO 



«-Indifulvine. Indigo-blue. Propylic aldebyde. 



C22H10NO3 = Ci«H^N02 + C^ H« 02-HO 



6-Indifulvine. Indigo-blue. 



C44Hi9N2 03=2C'6H5N02 + C'^ H^^ O'^-SHO 



Indiretine. Indigo-blue. Acetic acid. Propionic acid. 



C36Hi7NOio= C'^H^NO^ +3C4 H4 0^-^2C^Y{.^0^-^\iO 



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 decompo- 

 sition. Indeed all my experiments lead to the conclusion that 

 the elements are arranged in a manner very different from what 

 might be inferred from the above equations. If the nitrogenous 

 substances formed from indican, together with indigo-blue, were 

 copulated bodies containmg the latter, it would be possible to 

 obtain from them either indigo-blue itself, or its products of 

 decomposition. With the small quantities of these substances 

 which were at my disposal, I was unable to make many experi- 

 ments to decide this point. A tolerably large quantity of indi- 

 fuscise 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 until a small portion of it no longer dis- 

 solved in water with a dark brown colour. I was unable, how- 

 ever, to discover among the products of decomposition a trace of 

 anthranilic acid, which would probably have been present if in- 

 difuscine contained the elements of indigo-blue. 



Some advantage may nevertheless arise from looking at these 

 compounds from the point of view just presented, as their rela- 

 tion 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 elements 

 contained in indican which have formed a certain portion of in- 

 difulvine, indihumine, &c., might, under certain unknown cir- 

 cunistances, have produced equivalent quantities of indigo-blue, 

 and that the latter cannot therefore be said in any sense to pre- 

 exist in indican. 



fTo be continued. I 



