186 J. W. Mallet— Constitutional formulxz of Urea, 



amide. Bunte* has suggested as the means of deciding between 

 these opinions the determination of the maximum number of 

 isomeric products obtainable from the body in question bj 

 substituting an alcoholic radical for hydrogen. 



The most obvious point of difference between the three for- 

 mulae above mentioned consists in the first being symmetrical 

 while the others are not so. If urea be carbonic diamide (I), 



Lo 



the two nitrogen atoms are placed exactlv alike, and so are the 

 four atoms of hydrogen. If the third formula (2) be adopted, 

 the two nitrogen atoms will be unlike, while there will be two 

 pairs of hydrogen atoms with no difference between the mem- 

 bers of each pair. But if the formula (3) be the true one, the 

 two nitrogen atoms, while exhibiting the same atomicity, are 

 dissimilarly connected, and hydrogen is found in three different 

 relations to the rest of the molecule, only two atoms of the lat- 

 ter element being quite alike in position. Clearly we should 

 the rather expect from this highly unsymmetrical disposition 

 of the atoms such a number and varietv of substituted and 



onjugated products as urea actually affords. 

 But not only does this last view enable us 

 for the large class of derivatives furnished by the^substance i 



question, but it seems to lend itself remarkably well to the 

 explanation of the special character which these derivatives 

 severally exliibit, whereas many of the formulae hitherto pro- 

 posed for the " ureides" differ niuch from those of other bodies 

 of the same type, the acid or basic character, degree of basicity, 

 etc., not being satisfactorily accounted for. In this respect 

 Wanklyn, Gamgee and Gibbs seem scarcely to have done 

 justice to the merits of the formula they suggested, and I pro- 

 pose by a few examples of the better known substances related 

 to urea to illustrate the advantages of assuming for it this 

 molecular constitution. In doing so I have to suggest a struc- 

 tural composition for most of the conjugated bodies spoken of 

 unlike that which Gibbs has adopted in the paper above 

 referred to. It will conduce somewhat to clearness to iise fully 

 expanded graphic formulae, and for the conjugated compounds 

 * Ann. der Chem. u. Pharm., cli, 184. 



