88 REPORT OF THE CHEMIST OF THE 
We will consider the data contained in Table I under the head- 
ings given below. 
(1) Decrease of milk-sugar.—In all cases the loss of milk-sugar 
increases quite rapidly for 32 hours, after which additional change 
is slow and small. In 72 to 120 hours, the maximum loss is 
reached; in experiment No. 1, no further change of milk-sugar 
occurred after 72 hours; in No. 2, none after 96 hours. Of course, 
at temperatures somewhat higher, less time would be required 
for the transformation of the same amount of milk-sugar. Averag- 
ing our results, we find that about 11 per ct. of the sugar present 
in the milk at the start had disappeared in 8 hours; 21 per ct., 
in 24 hours; 25.5 per ct., in 32 hours; 26 per ct., in 48 hours; 
27 per ct., in 72 hours; and 27.6 per ct. in 96 hours. 
(2) Amount of lactic acid formed.—The maximum amount of 
acid, calculated as lactic acid, was about 0.90 per ct., which is 
equivalent to about 62 per ct. of the milk-sugar that disap- 
peared. It is customary to represent in the following man- 
ner the reaction by which milk-sugar is converted into lactic 
acid: 
Milk-sugar. Tactie acid. 
OC; H,, 0 +H, 0O=26, Hos 
According to this expression, all the milk-sugar is converted 
into lactic acid, weight for weight. While this equation expresses 
the most prominent chemical action that occurs, it certainly 
fails to give anything like a complete or accurate statement of 
the entire chemical action. In detail, our average results are as 
follows: In 24 hours, 40 per ct. of the milk-sugar that had disap- 
peared formed acid, lactic largely; in 32 hours, 58.5 per et.; in 
48 hours, 64 per ct.; in 72 hours, 63.3 per ct.; in 96 hours, 63.5 
per ct.; in 120 hours, 61.3 per ct. 
As shown by Kayser,’ there may be present in addition to 
lactic acid, as the products of the decomposition of milk-sugar 
by lactic-acid forming organisms, carbon dioxide gas, formic acid, 
acetic acid, acetone and alcohol. Mayer® has found that under the 
most favorable conditions, we may possibly be able to get as much 
as 83.9 parts of lactic acid from 100 parts of milk-sugar. The pres- 
8Ann. Past., 8:737 (1894). 
*Centralbl. Bakt., 12:99 (1892). 
