313 H. Caro and J. A. Wanklyn on the relation of [June 31, 



in alcohol, not soluble in water ; it is the salt of a red- coloured base. It 

 dissolves in strong sulphuric acid, giving a red solution. 



4. Submitted to destructive distillation, it gives abundance of carbolic 

 acid, leaving a carbonaceous residue. 



5. The deep-red solutions in alkalies are easily reduced on boiling them 

 •with zinc powder; so treated they lose their colour; but restoration of 

 the colour takes place on adding ferricyanide of potassium. 



There is only one particular in which any diiFerence could be detected 

 between the product obtained from rosaniline and that obtained from 

 carbolic acid by Kolbe and Schmitt's process. 



The rosolic acid of Kolbe and Schmitt forms salts the solutions of 

 which are darkened by ferricyanide of potassium. The product obtained 

 from rosaniline does not darken, or darkens only very slightly, on the 

 addition of ferricyanide. An explanation of this difference is afforded by 

 the following experimental facts. The product from rosaniline after re- 

 duction with zinc becomes capable of being darkened by ferricyanide ; and 

 if leucaniline, instead of rosaniline, be taken, there is obtained a cantharides- 

 like product, which gives red solutions with alkalies, but is darkened by 

 ferricyanide. Furthermore, if a solution of Kolbe and Schmitt's rosolic 

 acid be darkened with ferricyanide of potassium, and then precipitated by 

 the addition of an acid, there results a colour-acid, which dissolves in 

 alkalies, giving solutions of the exact tint of the rosaniline-product, and, 

 like it, incapable of being deepened by ferricyanide. The interpretation 

 of all this is, that the rosolic acid obtained from carbolic acid by the action 

 of sulphuric and oxalic acid (Kolbe and Schmitt) contains more or less 

 leuco-rosolic acid, produced probably by the reducing action of some sul- 

 phurous acid. The rosolic acid got from leucaniline also contains more or 

 less leuco-rosolic acid. The rosolic acid obtained from rosaniline is free, 

 or almost free, from leuco-rosolic acid. 



Be this, however, as it may, there can be no doubt that rosanihne and 

 carbolic acid give essentially the same product when the former is treated 

 with nitrous acid in the manner we have described, and the latter with 

 sulphuric and oxalic acids as in Kolbe and Schmitt's process. 



Adopting the " Ethylene type," we have the following expressions for 

 the reactions of rosaniline : — 



Rosaniline. Azo-rosaniline. 



fNCeH.H 

 NC, H,H 

 NCeH.H 

 H 



4- 



HNO, 

 HNO, 

 HNO, 



+ 



2H,0 

 2H,0 

 2H,0 



Rosolic Acid. 



rN,CeH3 



N,CeH3 

 H 



+ 



OCeH, 



+ 3N,. 



