PREPARATION OF LACTIC AND BUTYRIC ACIDS. 
203 
ART. LVIIL— ON THE PREPARATION OF LACTIC AND 
BUTYRIC ACIDS. 
By A. Bensch. 
In the preparation of lactic acid according to the process 
of M. Gobley, there is nothing to show when the meta- 
morphoses of the sugar into lactic acid has been effected, as 
he employs so much water that the lactate of lime formed 
remains almost wholly in solution. But since the formation 
of butyric acid begins as soon as the production of lactic 
acid is terminated, a great loss of lactic acid may readily 
occur, which may be easily prevented by using a smaller 
quantity of water. The addition of tartaric acid to the so- 
lution of sugar, in order to convert the cane into grape- 
sugar, and the addition of stinking cheese, facilitates the 
formation of lactic acid, and prevents the contemporaneous 
production of large quantities of butyric acid. 
The circumstance that the lime-salts prevent the separa- 
tion of the otherwise so sparingly soluble salts of zinc and 
protoxide of iron, does not allow of the employment of the 
lime-salt in the preparation of the above salts ; and I there- 
fore prefer decomposing it with sulphuric acid, and com- 
bining the lactic acid with oxide of zinc, as the purification 
of the lactate of zinc and the separation of the lactic acid 
from it present no difficulties. The mixture which I use for 
the preparation of lactic acid is essentially the same as that 
employed by Pelouze and Gelis for the preparation of butyric 
acid. 
Lactic Jlcid. — 6 lbs. of cane-sugar and h oz. of tartaric 
acid are dissolved in 26 lbs. of boiling water, and set aside 
for some days ; upon this, 3 oz. of old stinking cheese, well 
diffused in 8 lbs. of curdled acid milk from which the cream 
