New YorkK AGRICULTURAL EXPERIMENT STATION. 159 
(3) The lactose in the cheese decreases in amount quite rap- 
idly during the first 12 or 15 hours after the cheese is put in 
press and entirely disappears in about 2 weeks. 
(4) The acidity increases, reaching its approximate maximuin 
about the time the lactose disappears. The apparent increase of 
acidity later is due, in part, at least, to the presence of increased. 
amounts of water-soluble proteids. 
(5) The percentage of water-soluble calcium and phosphoric 
acid compounds increases quite rapidly during the first few hours 
after the cheese is put in press; the increase continues for some 
weeks but-at a slower rate. As we shall show later, the water- 
soluble phosphoric acid is present mainly as mono-calcium 
phosphate, and the water-soluble calcium is present in combina- 
tion mostly with phosphoric acid and with lactic acid. 
The rapid increase of salt-soluble nitrogen to a maximum, 
followed by subsequent decrease, suggested the probability that 
the insoluble proteid of the fresh curd is completely converted 
into the salt-soluble form before the change into another form, 
insoluble in water and salt-solution, begins; but that the action 
is so rapid that it is difficult to get a sample at just the point 
when the nitrogen, originally insoluble, is entirely in the salt- 
soluble form. The probable truth of this suggestion appeared 
to be indicated by the fact that in one case when we were work- 
ing on another point we were able to dissolve the insoluble 
cheese proteid completely in salt-solution. 
From ,the suggestions afforded by the results obtained, it 
seemed desirable to make further study with the specific object 
of ascertaining: (1) Whether all the insoluble proteid of fresh 
cheese is changed into a salt-soluble form before it again becomes 
insoluble in salt-solution, and (2) what relation there might be 
between the formation of salt-soluble nitrogen and the formation 
of water-soluble calcium phosphate, and (3) whether the calcium 
of the calcium lactate that is formed comes wholly from the 
calcium of the insoluble phosphates or in part from the calcium 
of calcium paracasein. 
THIRD EXPERIMENT. 
For carrying out this study, another cheese was made July 9, 
1906, from normal milk, the results of which are embodied in 
Tables III and IV. In order to obtain a sample of cheese when 
the nitrogen should be all in the form of the salt-soluble sub- 
stance, it was necessary to take samples at more frequent in- 
