1872.] 



Derivatives of Uramidobenzoic Acid. 



175 



responding salt of the acid just described. It is almost entirely deposited 

 on cooling in white, soft, shining, almost oval-shaped plates. 



y diamidohenzoic acid crystallizes in long yellowish-white needles, whose 

 solubility closely resembles that of the two other isomeric acids. Its sul- 

 phate forms white six-sided tables or prisms, which, when dried in the air, 

 have the composition (C 7 H 8 N 2 2 ) 2 , SH 2 4 + 1|H 2 ; they are almost as 

 insoluble as the corresponding compound of the a diamido-acid. When 

 the solution of y diamidobenzoic acid in dilute hydrochloric acid is decom- 

 posed by ferric chloride, a hrownish-red semicrystalline precipitate is ob- 

 tained, consisting of a new acid, which, however, I have not at present 

 more closely investigated. 



Action of Nitrous Acid on the Isomeric Diamidobenzoic Acids. 



In this reaction a remarkable difference is observed between the a dia- 

 midobenzoic acid on the one hand and ft and y diamidobenzoic acids on 

 the other. When a diamidobenzoic acid is treated with a quantity of warm 

 and moderately dilute hydrochloric acid, insufficient to dissolve the whole, 

 and on cooling the filtered solution is mixed with one of sodium nitrite, a 

 semisolid mass of crystals is formed. These, after separation of the mother- 

 liquor, are easily purified by crystallization from hot water, with the ad- 

 dition of a small quantity of animal charcoal. The compound thus ob- 

 tained forms long needles or small plates, which explode when heated in a 

 dry state. It is rather easily soluble in hot water, and by long boiling gra- 

 dually decomposes, giving rise to a brown insoluble amorphous precipitate. 

 Curiously enough it does not possess acid properties, being insoluble both 

 in ammonia and potassa ; whilst, on the contrary, it combines with the 

 mineral acids, forming well-crystallized salts. Its hydrochlorate forms 

 six-sided plates, which are readily soluble. Unfortunately I have not yet 

 been able to establish the composition of this basic compound with cer- 

 tainty, although from a determination of the gold in its gold salt, which 

 crystallizes in dark yellow needles, I believe it to have the composition 

 indicated by the formula C u H 13 N 3 4 . Its formation, therefore, would 

 take place in the following manner : — 



2(C 7 H S N 2 4 ) + NH0 2 = g, «H ? g.O < + ^0. 



a diamidobenzoic Nitrous acid. New compound. Water, 

 acid. 



It is necessary to mention that this basic compound is not formed when 

 sodium nitrite acts upon a diamidobenzoic acid in the presence of free 

 hydrochloric acid, instead of in the manner just described. In this case 

 a brisk evolution of nitrogen takes place, and after some time the yellow 

 solution deposits an amorphous reddish-brown acid. 



The behaviour of the two other isomeric diamidobenzoic acids under 

 the circumstances previously mentioned is quite different to that of the 

 a diamidobenzoic acid. When their solution in dilute hydrochloric acid 



