Gerkardfs Organic Chemistry. 177 



while those, like the sulpho-succinic, derived from the bibasic 

 acid, are tribasic. The sulphuric acid is bibasic,* and from these 

 facts we deduce the law, that the basicity or capacity of saturation 

 in a coupled salt is always less by one than the sum of the basi- 

 cities of its components. Thus sulpho-vinic acid is formed from 

 one equivalent of a bibasic acid and one of alcohol, which is 

 neutral, and is monobasic (2 + 0) -0 = 1. The sulpho-succinic 



acids 



1 = 3. 



This law is applicable to all cases of accouplement. The phos- 

 phoric acid, which is tribasic, unites with alcohol to form a bi- 

 basic acid. Similar coupled acids are formed by oxalic, carbonic, 

 tartaric acids and others with the alcohols. 



The couples of sulphuric acids are often found by the sim- 

 ple mixture of the two bodies, but with the hydro-carbons of a 

 nigh equivalent it is necessary to dissolve them in the fuming 

 acid or expose them to the vapor of anhydrous sulphuric acid, 

 and then heat the product with water; in this way the sulpho- 

 acetic acid was formed by Melsens. The lime and baryta salts of 

 all these acids are soluble in water, although the sulphates of 

 these bases are quite insoluble— (Precis, pp. 98-104.) 



1 he nitric acid being monobasic does not form coupled acids 

 with neutral bodies like alcohol, but its action upon monobasic 

 acids yields a series of azotized acids which are themselves mo- 

 nobasic as (14-1) -1 = 1. The benzoic acid, when boiled for 

 sortie time with strong nitric acid, yields the nilrobenzoir, which 

 contains the elements of one equivalent of each of the acids 

 minus one equivalent of water. C 7 H 6 0„ +NHO, =C 7 H, N0 4 4- 

 a »0. The residue of the nitric acid NH0 3 -0 = NH0 3 

 must be regarded as replacing H„ in the acid ; which is conse- 

 quently C 7 (H 4 NH0 2 ) 2 ; it is scarcely distinguished from 

 normal benzoic acid in its" characters. These acids and their 

 salts are characterized by exploding when suddenly heated. The 

 action of nitric acid upon phenol gives rise to a curious azotized 

 ^pound. described at different times as the bitter principle of 

 Welter, carbazotic, picric, nitro-picric and nitro-phenisic acids, 

 "is the final product of the action of nitric acid upon indigo, 

 , lcine and many other bodies, but is directly formed from phe- 

 *? [ by the same process. Its formula is C„ H, N, 7 , while 

 Pnenoi is C 6 H p O, and it is derived from this by the complete 

 ^Placement of its hydrogen by the residue of nitric acid ; it may 

 * rfinrQrn "'- J ' ~ (NHO,) 3 = 0; the strongest nitric acid is 



tot ally without action upon it 



,__ as monobasic, the existence 

 anic substances, clearly show 



Sept., 1847. 



