164 REPoRT OF THE CHEMIST OF THE 
extract from 100 grams of cheese neutralizes 120 to 130 ¢. ¢. 
of N-io alkali. 
(4) The lactose in this and the preceding experiments seems 
to disappear in one to two weeks. The rapidity of conversion 
of lactose into lactic acid depends upon temperature as one con- 
dition and this fact must be considered when we attempt to 
make comparison of results given by different experiments. 
Under the conditions of our work in this experiment, the tem- 
perature was lower while the cheese was in press than in the 
case of the other experiments. 
(5) The amount of water-soluble calcium compounds increases 
at different rates in different experiments. Comparing this witn 
the preceding, we notice that when cheese is put in press it 
contains .45 to .55 per ct. of CaO, which increases to .60 to .65 
per ct. in 24 hours and in 2 weeks or more reaches about .75 
per ct. About 80 per ct. of the total calcium in the cheese 
becomes ultimately converted into water-soluble calcium com- 
pounds. This appears to take place within 2 weeks, which is 
roughly coincident with the time at which the lactose in the 
cheese finally disappears. 
(6) The water-soluble P,O, increases quite rapidly for 9 or 
10 hours after the cheese is put in press and then remains quite 
constant, the inorganic P,O; all appearing in the water-extract. 
This complete change appears to take place in this experiment 
much more quickly than in the preceding one. In both cases, 
the maximum amount of water-soluble CaO is reached, when 
all the inorganic P,O, appears in the water-extract. 
(7) The results in determining total ash and water-soluble 
ash are inserted here for convenience of future reference. They 
do not now appear to’give any information not furnished by the 
other data. 
Lik -THE;, ACIDITY »OF). THE, ,WATER-EX TRAGIe 
CHEDDAR CGHEESE. 
The acidity of cheddar cheese is often discussed as if it were 
due to the presence of free lactic acid in the cheese. This is 
illustrated by the fact that in the provisional official method? for 
determining acidity in cheese, the instructions are to express 
the result as lactic acid. However, we have been unable to 
isolate free lactic acid from normal cheddar cheese or to obtain 
1U. S. Dept. Agr., Chem. Bul. 46, rev. ed., p. 56. 
