168 REPORT OF THE CHEMIST OF THE 
the latter diminished, the relation was extremely irregular and 
no explanation of this irregularity could be offered. The irregu- 
larity referred to can be readily seen by referring to the nu- 
merous analyses of cheese published in previous bulletins of this 
Station. The reason of this lack of uniform relation between 
salt-soluble and water-soluble proteid is now quite clear, if we 
understand that an intermediate insoluble proteid is formed, 
and that this precedes by some time the rapid formation of 
water-soluble proteids. 
CHANGES: IN. CALCIUM : AND ‘PHOSPHORIC = ACID | COMPOUNDS aa. 
CHEDDAR CHEESE. 
Simultaneously with some of the changes occurring in the 
proteids, we have changes taking place in the inorganic con- 
stituents of the cheese, especially the calcium and phosphoric 
acid compounds. ‘Tricalcium phosphate is the principal phos- 
phate in fresh cheddar cheese-curd. There is probably some 
dicalcium phosphate and also small amounts of tri- and di- 
magnesium phosphates, but these details are immaterial at this 
time. The main fact. is that the calcium and phosphoric acid 
compounds of cheese which are insoluble at the start, gradually 
become soluble until about 80 per ct. of the calcium and all of 
the phosphates appear in water solution. This change is due 
to the formation of lactic acid and its action upon the phos- 
phates of the cheese, changing insoluble into soluble phosphates 
and forming at the same time calcium lactate. The maximum 
amount of calcium is found in water solution at about the same 
time the phosphoric acid becomes entirely water-soluble. This 
appears to indicate that the water-soluble calcium present in 
cheese in its early history comes from inorganic combinations, 
mainly tri-calcium phosphate, and not from the calcium com- 
bined with paracasein as calcium paracasein. 
Another point of interest in connection with the calcium of 
cheese is that we find calcium present in the salt-soluble portion 
of cheese. In the cases in which special determinations have 
been made we find that about 20 per ct. of all the calcium in 
the cheese is in the salt-soluble portion. This suggests that the 
salt-soluble proteid either holds calcium salts mechanically or 
that the proteid molecule is still combined with calcium or some 
calcium compound and is not entirely calcium-free as we have 
previously believed. In the case of some unpublished work done 
