270 



new compound in a state of purity. The sub'stance thus obtained 

 presents the same composition as the product of the action of dibro- 

 mide of ethylene-diethyldiammonium on cyanate of silver, viz. 

 C 8 H 18 N 4 2 . 



The two ureas, however, are far from being identical. The urea 

 obtained by combining cyanate of ethyl with ethylene-diamine is 

 easily soluble in boiling water, difficultly soluble in cold water, even 

 less soluble in spirit, and almost insoluble in absolute alcohol. It 

 fuses, without decomposition, at 201, solidifying again at 185. 

 This body is altogether indifferent. I did not succeed in obtaining a 

 platinum-salt or a gold-salt of this urea, while the isomeric substance, 

 derived from ethylene-diethylamine, furnishes both salts without diffi- 

 culty. 



The non-identity of the two bodies is thus sufficiently established, 

 but the absolute difference in their construction is most conspicuously 

 manifested in the products of decomposition, which they yield under 

 the influence of the alkalies. Treated with potash, the urea, derived 

 from ethylene-diethyldiamine and cyanic acid, yields ethylene-di- 

 ethyldiamine and the products of decomposition of cyanic acid, 

 carbonic acid and ammonia : 



C 8 H 18 N 4 2 +4KHO=2K 2 C0 3 + 2H 3 N + C 6 H 16 N 2 . 

 The urea, on the other hand, which is formed by the action of 

 ethylene-diamine on cyanic ether, splits into ethylene-diamine and the 

 derivatives of cyanic ether, carbonic acid and ethylamine : 



Tt is thus evident that the two individual groups of elements, the 

 union of which gives rise to the two different ethylated ethylene- 

 ureas, remain as such unaltered in these compounds. 



The observations which I have recorded render it very probable 

 that many of those substances known as compound ureas, and 

 hitherto supposed to be identical, might on closer examination prove 

 to be isomeric only. 



Diethylurea, obtained by treating cyanate of ethyl with ethylamine 

 or with water, differs indeed most conspicuously in its properties 

 from diethylurea, produced by the action of cyanic acid on diethyl- 

 amine. Under the influence of potash these two bodies split, the one 

 into carbonic acid and ethylamine, the other into carbonic acid, am- 

 monia, and diethylamine. Even the ethylurea, prepared by cyanic 



