PREPARATION OF LACTIC AND BUTYRIC ACIDS. 205 
of lactate of zinc yield in this manner 5 parts of perfectly pure 
syrup lactic acid. 
Butyric Acid. — When the above mixture of sugar, chalk, 
&c. is left longer than ten days at 95°, and the evaporated 
water renewed, the mass again becomes liquid, gas bubbles 
are given off, and in from five to six weeks the lactic acid 
is converted into butyric acid, and the evolution of gas 
ceases. The liquid is now mixed with an equal volume of 
cold water, and a solution of 8 lbs. crystallized soda added ; 
the corbonate of lime collected on a filter, and well washed ; 
the liquid evaporated to 10 lbs., and mixed cautiously with 
5| lbs. of sulphuric acid, which has previously been diluted 
with an equal weight of water. Butyric acid separates as 
a dark-coloured oily layer upon the solution of the bisulphate 
of soda, and can be readily separated by a separating funnel. 
The solution of bisulphate of soda is submitted to distilla- 
tion, the product saturated with carbonate of soda, the 
butyric acid likewise separated after evaporation by sul- 
phuric acid, and the crude butyric acid rectified, after the 
addition of I oz. of sulphuric acid for every pound, in order 
to prevent the separation of anhydrous sulphate of soda, 
which would cause a violent thumping. The dilute rectified 
butyric acid is saturated with fused chloride of calcium, 
which separates the acetic acid, and then again submitted 
to distillation. The first portion that passes is dilute butyric 
acid containing traces of muriatic acid ; this is succeeded by 
concentrated butyric acid, and there is left in the retort a 
small quantity of chloride of calcium and brown-coloured 
butyric acid. 
Pelouze and Gelis distilled the crude butyrate of lime 
with muriatic acid ; this operation requires very large re- 
torts, as a violent frothing is unavoidable ; moreover, by this 
method the butyric acid is rendered very impure by muriatic 
acid, two evils which are avoided by the method I have 
proposed. I obtained from 6 lbs. of cane-sugar 28 oz. of pure 
concentrated butyric acid. — Qh. Gaz., from Liebig's Ann- 
