190 CONJUGATED ACIDS. 



acid, with oil of bitter almonds and sugar as an adjunct. If hippuric 

 acid were actually composed in this manner, the products of 

 decomposition with peroxide of manganese, could be hardly dif- 

 ferent from what they are, for hydrocyanic acid is very readily 

 decomposed into formic acid and ammonia, and the oxygen yielded 

 by the manganese converts the formic into carbonic acid, and the 

 hydride of benzoyl into benzoic acid both being processes of very 

 frequent occurrence. But independently of the circumstance that, 

 at least in analogous processes, some formic acid remains undecom- 

 posed, this view is also opposed by the fact that other oxidising 

 agents do not decompose hippuric acid in the same manner which 

 they undoubtedly would do if the acid actually had this composition. 

 On this account Fehling,* influenced by the behaviour of hippuric 

 acid with peroxide of lead, regarded it as fumaric acid conjugated 

 with benzamide, and=r:H 2 N.C 14 H 5 O 2 + C 4 HO 3 .HO. If benzoic 

 acid existed preformed in hippuric acid, it would be very unlikely 

 that, by the action of an oxidising agent, as peroxide of lead, a 

 substance so poor in oxygen as benzamide should be formed. 



Dessaigne's remarkable discovery must lead to the conclusion 

 that glycine exists preformed in hippuric acid, and is conjugated 

 with benzoic acid, so that 1 atom of anhydrous glycine with 1 atom 

 of benzoic acid forms hydrated hippuric acid, since C 4 H 4 NO 3 + 

 C 14 H 5 O 3 =C 18 H 8 NO 5 .HO ; but if we are not altogether opposed to 

 Streckei^s formula for the formation of conjugated compounds from 

 their constituents with the loss of certain atoms of water, yet it ap- 

 pears to us simple and natural that we should only compare with one 

 another the formulae of anhydrous combinations, and that certain 

 atoms of water should not be arbitrarily abstracted; anhydrous 

 glycine and anhydrous benzoic acid yield 1 atom of hydrogen and 

 1 atom of oxygen more than anhydrous hippuric acid contains : if 

 now, notwithstanding this, we assume that glycine exists preformed 

 in hippuric acid, with however only a small quantity of water, we 

 should proceed just as irrationally as if we assumed that ammonia 

 existed in oxamide or in benzonitrile, because these bodies, when 

 they assimilate water, yield ammonia. All, therefore, that we can 

 maintain is, that in hippuric acid we find, in addition to benzoic 

 acid, an adjuncts C 4 H 3 NO 2 , which, on its separation, has a strong 

 tendency to be transformed into glycine a substance which is as 

 readily formed as urea in the decomposition of nitrogenous matters, 

 (see pp. 152 and 158.) It is in the changes which the adjunct under- 

 goes in its intimate constitution by the action of stronger agents, that 

 * Ann, d. Ch. u. Pharm. Bd. 28, S. 48. 



