J. W. Mallet— Constitutional formulae of Urea, etc. 185 



the received laws, if simple ex 

 have also designed a modifical 

 results when a uniform motion is given to the slide. 



The experiments in the series (nearly 100 in number) and a 

 greater part of the computations have been verj carefully 

 made by Messrs. Butterfleld and Wilson, students in the 

 department of Physics. 



Art. XXIII.— On the constitutional formulm of Urea, Uric Acid, 

 and their derivatives ; by Professor J. W. Mallet, University 

 of Virginia. 



Few classes of organic compounds have given rise to more 

 difference of opinion amongst chemists than that which includes 

 urea and its conjugates. 



The remarkable number of such compounds, their compli- 

 cated relationships, the varied circumstances of their production 

 and decomposition, and their variety of chemical character, 

 have led to nearly every one of them being viewed in several 

 different lights, and represented by several different formulas, 

 by those who have given the subject special attention. 



The structure of the simple molecule of urea itself is by no 

 means settled. The arguments of Heintz* and Kolbef in favor 

 of the view that urea is identical with carbamide (H^N— CO 

 — NHg) have been opposed by the observation of Wanklyn 

 and Gramgeeij: as to the behavior of urea (unlike that of admitted 

 amides) when oxidized by an alkaline solution of potassium 

 per-manganate. The latter chemists proposed the formula 



((nhI- 



C { NH„, but, as Watts remarks in his Dictionary of Chem- 



, (OH 



istry,§ without assigning specific reasons (other than the dif- 



proposed 



ference of behavior just noted) for adopting this instead of the 

 carbamide formula which they reject. Wolcott Gibbs j inde- 

 pendently put forward the same view, but did give some of the 

 ' 1 upon which it was adopted by him. It has also been 

 present urea as 0-C=NH,— NH„ in which 

 I the nitrogen atoms is pentad. Most recent 

 writers of text-books, however, as Fittigt and Naquet,** seem 

 to have fallen back upon the view that urea is simply carb- 

 * Ann. der Chem. u. Pharm., cxl, 216 ; cl, 73. f Zeitsehr. fiir Chem., II, iii, 50. 



iJour. Chem. Soc, Jan., 1868, 31. § Ist Suppl., 1115. 



Amer. Jour. Sci., II, xlvi, 290, Nov., 1868. 

 WoHer's Grundriss der org. Chem., 8te. Aufl., 206. 

 Principes de Chimie, trois^me ed., t. ii, 532-533. 

 Am. Jour. Sci.-Thikd Series, Vol. XI. No. 63.-Majich, 1876. 



