Uric Acid, and their derivatives. 187 



to use dotted lines to represent the bonds connecting residues 

 derived from different molecules.* 



Let then urea be represented by the last formula, No. 3, 

 derivable from ammonium cyanate 



by mtermolecular transposition, and from ammonium carb- 

 amate by change of the same sort with elimination of water. 

 In both cases (me of the two nitrogen atoms shows the usual 

 tendency to revert from pentad to triad character by elevation 

 of temperature. 



The direct compounds of urea (like those of ammonia) with 

 acids involve a re-assumption of pentad relation by this one 

 atom of nitrogen ; not by both, as we might expect if they 

 were alike in position in the molecule ; as, for instance, in the 



i 



Similar relations ar 

 for instance raercu 

 chloride. ' 



e entered into with some metallic oxides, 

 ric oxide, and certain salts, as with sodiu 



1. Ethyl-urea (basic). 2. Normal di-ethyl-urea (basic). 

 HHH HHH HHH 



H-C_H H-C-H H-O-H 





0-H C-O-H 



not for (iifflculty on the part of the printer 



