66 
ME. M. SIMPSON ON THE SYNTHESIS 
Formation of Pyrotartaric Acid. 
A mixture of one volume of cyanide of propylene, distilling between 265° and 290° C., 
and about volume of strong hydrochloric acid, was exposed in a glass tube herme- 
tically sealed to the temperature of a water-bath for about six hours. 
Long before the expiration of this time the contents of the tube had become a mass 
of crystals. These were dried at 100° Cent., and dissolved in absolute alcohol. The 
residue obtained on evaporating the alcoholic solution was then twice crystallized from 
water, and finally dissolved in ether, in order to remove the last traces of the ammo- 
niacal salt formed in the process. The body obtained on distilling ofi" the ether is the 
acid in question. It was dried at 100° Cent, and analysed. The numbers obtained 
correspond with the formula of pyrotartaric acid, as will be seen from the foUorving 
Table : — 
Theory. Experiment. 
per cent. 
I. 
II. 
^10 
. 60-00 
45-45 
44-60 
44-58 
Hg 
. . 8-00 
6-06 
5-83 
5-70 
Og. 
. . 64-00 
48-49 
132-00 
100-00 
It had also all the properties ascribed to this acid by Pelouze and Aeppe. The 
crystals were colourless and very soluble in water, alcohol and ether. It had an agree- 
able acid taste, and expelled carbonic acid from its combinations with the alkalies. It 
became semifluid at 100° Cent., and melted completely a few degrees above that tempe- 
rature. 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 dis- 
solved in boiling water, recovering at the same time its acid reaction. Lime-water was 
not affected by a solution of this acid. Neutralized by ammonia, it gave a white curdy 
precipitate with nitrate of silver. Acetate of lead caused no precipitate "with the 
neutralized acid. On the addition, however, of alcohol to the mixed solutions, a bulky 
white precipitate was obtained, which melted into oily drops on heating the liquid in 
which it was suspended. The following equation will explain the reaction which gives 
rise to this acid: — 
Cfi He Cy2 + 2H Cl + 8HO = C^o Hg Og + 2(N Cl). 
Pyrotartaric acid bears the same relation to propylglycol that butyric acid bears to 
propylic alcohol: — 
C6l^4 
Propylglycol. 
Cio^s 
Pyrotartaric Acid. 
Propylic Alcohol. 
Cgj^ 
Butyric Acid. 
The claims of this acid to be considered the homologue of succinic acid, which some 
