[harding] 



THE "NINHYDRIN" REACTION 



39 



a reaction which is readily observable. In this manner the requisite 

 glyoxal is produced and the mechanism is then supposed to follow the 

 usual path with the unchanged triketone. 



INFLUENCE OF REDUCING AGENTS ON THE 

 WITH AMMONIUM SALTS. 



NINHYDRIN REACTION 



Reducing agents should assist the auto-reduction of triketo- 

 hydrindene hydrate and thus increase the amount of coloring matter 

 formed by ammonium salts. From this point of view we have exam- 

 ined the action of a number of common organic reducing agents, 

 which might be supposée! from a knowledge of their reactions, not to 

 interfere with any of the further condensations which take place, 

 and measured their influence on the amount of coloring matter formed 

 from ammonium chloride. 



The following table shows in detail the influence of glucose on 

 the decomposition of the ammonium salts. 



THE NINHYDRIN REACTION APPLIED TO AMIDES AND AMINES. 



One or two instances are given in the literature showing a negative 

 result on applying the "ninhydrin" reaction to amides. We have 

 examined several different classes of amides, in various concentrations, 

 with and without the presence of pyridine, and in the former case 

 found the reaction to be very faintly positive. The amount of color 

 produced by any of the amides is much too small to be measured, 

 or for the ammonium salt of diketohydrindylidene-diketohydrindamine 

 to be detected with certainty; the only positive evidence is that the 

 bluish-violet color is resistant to mild oxidation. 



