New YorK AGRICULTURAL EXPERIMENT STATION. 179 
when all the inorganic phosphorous became water-soluble. It 
was also noticed that the water extract of cheese is usually 
neutral or nearly neutral to litmus and quite strongly acid to 
phenolphthalein. If the acidity were due to lactic acid tne reac- 
tion towards litmus would be as strong as towards phenolph- 
thalein. This would be the case in a cheese less than 12 days 
old. ' Up to that time the amount of water-soluble proteids is 
quite small and constant and does not influence the acidity. 
The reaction of the cheese mass towards litmus is decidedly 
acid, due to the paracasein which reacts acid to litmus in the 
state in which it is found in cheese. 
CHANGES IN THE CALCIUM. 
Parallel with the other changes noted above, a change in the 
calcium is found. This is gradually rendered water-soluble but 
does not reach 100 per ct. of the total calcium until after all 
the phosphates have become soluble. This is due to the faci 
that the calcium is present in two combinations, with the phos- 
phoric acid and paracasein. The calcium combined with the 
phosphoric acid is all rendered water-soluble before that com- 
bined with the paracasein. 
The change in the calcium is directly connected with the 
changes in the proteids. 
CHANGES IN THE PROTEIDS. 
By an examination of Tables III and IV it will be seen that 
the solubility of the proteid in 5 per ct. salt solution under- 
goes rapid changes. After 10 hours the salt-soluble nitrogen 
amounts to 54.72 per ct. of the total nitrogen and then drops 
to 28.91 per ct. The question at once arose as to whether 54.72 
per ct. was the maximum amount of salt-soluble nitrogen formed 
or whether it at some time reached 100 per ct. of the total 
GAILOPen: 
This salt-soluble nitrogen is formed by the decalcification 
(either partly or wholly) of the calcium paracasein by the lactic 
acid which is produced by the action of bacteria upon the 
milk sugar. 
This change in the paracasein takes place quite rapidly and 
in order to study this point a special set of cheeses was made. 
In making normal cheese the ripening of the milk allows the 
~ development of a great number of bacteria and the change in 
