CHAP. IX.] THE CONTRACTILE TISSUES. 363 



of crystallization (18-178 per cent.). It is insoluble in alcohol ; but soluble 

 in 6 parts of boiling water and 58 63 parts of water at 14 15 0. 



Derivatives Both sarcolactic acid and the acid product of fermenta- 



of the ethyli- tion yield exactly the same derivatives or products of 



dene lactic decomposition when subjected to identical processes, so 



that we are justified in considering them to have the 



same chemical constitution. 



When heated for some hours in the water-bath, the lactic acids yield 

 the body termed lactic anhydride, C 6 H 10 O 5 ; when heated at a higher 

 temperature, 140 or 150, lactide, C 3 H 4 O 2 , is formed. 



When oxidized with dilute chromic acid the ethylidene lactic acids 

 yield acetic and formic acids but no malonic acid. 



Many synthetic processes are known which yield the inac- 

 Synthesis tive ethylidene lactic acid of fermentation ; the most instruc- 

 tive, as bearing upon the constitution of the acid, consists in 



tic acid. heating ethyloxycyanide of ethylidene 4 with 



\C 2 H 5 JO/ 



aqueous solutions of the alkalies, when ammonia and common lactic acid 

 and a small quantity of ethylene-lactic acid are formed. 



c. Ethylene-lactic Acid. 



This acid undoubtedly accompanies optically active ethylidene lactic 

 acid in the juice of flesh. 



Prepara- This has been described in part under 'sarcolactic acid.' 



tion. The alcoholic fluid from which sarcolactate of zinc has 



separated contains ethylene-lactate of zinc, which may be obtained from it 

 by evaporation. From the zinc compound, the free acid may be liberated, 

 by following precisely the same process as was recommended for the separa- 

 tion of sarcolactic acid. 



Is optically inactive. 



Its zinc salt has the same composition as that of sarco- 

 lactic acid, losing when heated in the water-bath 12 '9 per cent, of its 

 weight. The zinc salt, unlike that of the isomeric lactic acid, is exceedingly 

 soluble in water ; it is also much more soluble in alcohol. 



Products of When oxidized by means of chromic acid, ethylene- 



oxidation. lactic acid yields malonic acid (C 3 B[ 4 O 4 ). 



By heating ethylene chlorhydrate with potassium cyanide 

 the nitrile of ethylene-lactic acid is formed j thus 



CH 2 C1 OH,. ON 



+ TTf + 



CH 2 OH CH 2 .OH 



Ethylene Potas- Cyanhydrin. Potas- 



Chlorhydratc. sium siuin 



cyanide. chloride. 



