1872.] 



Derivatives of Uramidobenzoic Acid. 



171 



respective barium salts, this is easily effected by adding a slight excess of 

 hydrochloric acid to the hot aqueous solutions of the latter, the acids 

 crystallizing out on cooling. 



a nitrouramidobenzoic acid, C 8 H 7 (N0 2 ) N 2 3 . — This acid crystallizes 

 in bright yellow needles or small plates, which are difficultly soluble in hot 

 water, and but very slightly so in cold water and ether. Boiling alcohol 

 dissolves it readily. Its salts have the general formula C 8 H (NO 2 )N 2 O 3 , M', 

 and are as a rule soluble with difficulty. 



ft nitrouramidobenzoic acid, C 8 H 7 (N0 2 ) N 2 3 . — This acid crystallizes 

 from its hot aqueous solution in very slender bright yellow needles, closely 

 resembling in appearance its barium salt previously described. It is nearly 

 insoluble in cold water, and only very slightly in hot ; by boiling alcohol, 

 however, it is taken up in considerable quantities. It is mono-basic like the 

 a acid. 



y nitrouramidobenzoic acid, C 8 EL (N0 2 ) N 2 3 , is obtained in small 

 yellow scales, which are but very slightly soluble in all neutral solvents. It 

 is mono-basic, and almost all its salts are more readily soluble than the cor- 

 responding salts of the other isomeric acids ; moreover it is readily di- 

 stinguished by the decomposition which it undergoes when boiled with water 

 for a considerable time. It is then gradually dissolved, splitting up in the 

 following manner : — 



C 8 H 7 N 3 5 + H 2 = C 7 H 6 N 2 0, + C0 2 + N H 3 . 



The compound, C 7 H 6 N 2 4 , thus formed is also an acid which will be 

 described further on. The salts of the y nitro-acid likewise suffer a similar 

 decomposition when their aqueous solutions are boiled ; and the substance 

 mentioned in the footnote on p. 1/0, as crystallizing in yellowish-red 

 needles, is the barium salt of the acid C 7 H 6 N 2 O^, formed in this way. 



Action of Tin and Hydrochloric Acid on the Isomeric 

 Nitrouramidobenzoic Acids. 

 When a nitrouramidobenzoic acid is heated with tin and hydrochloric 

 acid, it is reduced in the ordinary way, yielding a amidouramidobenzoic 

 acid, C 8 H 9 N 3 3 = C 8 H 7 (N H 2 ) N 2 3 , crystallizing in scales, ordinarily 

 of a greyish-white colour. It is but slightly soluble in boiling water, still 

 less so in hot alcohol, and almost insoluble in ether. Its silver salt is a white 

 precipitate, having the formula C 8 H 8 N 3 3 Ag. Its hydrochloric-acid 

 compound, C 8 H 9 N 3 3 , HC1, crystallizes in scales, and is marked by its great 

 insolubility in hydrochloric acid, even when very dilute. When the aqueous 

 solution of the latter compound is acted upon with sodium nitrite, an azo- 

 compound separates, crystallizing in needles, which are soluble in hydro- 

 chloric acid. 



ft nitrouramidobenzoic acid also, when treated with tin and hydrochloric 

 acid, is converted into an amido-acid, C 8 H. (NH 2 ) N 2 3 , isomeric with that 

 last described. This new acid, which I call ft amidouramidobenzoic acid, 



