192 



tion was then twice crystallized from water, and finally digested 

 with ether. The body left on distilling off the ether is the acid in 

 question. The numbers obtained on analysis agree very well with 

 the formula of pyrotartaric acid ; I got 44*6 instead of 45 '4 per cent, 

 of carbon. It had also all the properties ascribed to this acid by 

 Pelouze and Arppe. The crystals were colourless, and very soluble 

 in water, alcohol, and ether. It had an agreeable acid taste. It 

 became semi-fluid at 100 Cent., and melted completely a few 

 degrees above that temperature. Long -continued ebullition in 

 a glass tube converted it into an oil, which was insoluble in cold 

 water, and no longer affected litmus-paper, but which gradually 

 dissolved in hot water, recovering at the same time its acid reaction. 

 The following equation will explain the reaction which gives birth 

 to this acid : 



C 6 H 6 Cy 2 +2HCl+8HO=C 10 H 8 8 +2(NH 4 Cl). 



It is highly probable that there exists a series of isomeric acids 

 running parallel to these, which may be obtained by similar pro- 

 cesses from the diatomic radicals contained in the aldehydes. Thus 

 from cyanide of ethylidene k r (C 4 H 4 Cy 2 ) we may hope to get an 

 isomer of succinic acid. 



I propose to continue my researches in this direction, and to ex- 

 tend them to the cyanides of the triatomic radicals. 



III. " On the Elimination of Urea and Urinary Water, in rela- 

 tion to Period of the Day, Season, Exertion, Food, and 

 other influences acting on the Cycle of the Year." By 

 EDWARD SMITH, M.D., F.R.S. Received April 15, 1861. 



The reading of this paper was not concluded. 



