ACTION OF NITROGEN 123 



Next let us proceed to the cyanogen substitution products 

 of methane : 



NCCH 3 , (NO), CH 2 , (NC) 3 CH, 



the first, acetonitril, shows no tendency to form salts; the 

 second, malonitril, on treatment with ammoniacal silver 

 nitrates takes up two atoms of silver; the third, cyanoform, 

 is not yet known. 



The effect of cyanogen is, however, most striking in this 

 group : 



OCCH 2 CO, 



which without it is capable of taking up metals (p. 121). 

 The combination 



OCCH(CN)CO 



carries such a decided acid character with it that, e.g. 

 cyanmalonic ethyl ester 



C0 2 C 2 H 5 CHCNCO 2 C 2 H 5 , 



is capable of decomposing carbonates l . Accordingly also 



dicyanacetic ester 



CH(CN) 2 C0 2 C 2 H 5 , 



behaves as an acid whose salts can be crystallized out from 

 water 2 . 



A corresponding joint influence of oxygen and nitrogen 

 is seen, as already mentioned, in the nitro group 



NO 2 . 



This appears in the somewhat marked acidity of picric acid, 

 C H 2 (N0 2 ) 3 OH, 



for example, as compared with phenol. The dissociation 

 constants of the nitrobenzoic acids show the same thing 3 : 



Benzole o-nitro m-nitro p-nitro 



0-00006 0-00616 0-000345 0-000396 



(3) Persistence of Negative Character and Valency. 

 Whilst the multivalent elements appear to form ions with 



1 Berl. Ber. 15. 2244. 2 Haller, Compt. Rend. nr. 53. 



3 Ostwald, Zeitschr.f. Phys. Chem. 3. 419. 



