New York AGRICULTURAL EXPERIMENT STATION. 173 
An examination of this table shows that the amount of nitrogen, 
in the form of the salt-soluble product, was increased very greatly 
by the action of the added lactic acid. The cheeses made without 
acid shows small amounts of this salt-soluble substance. In the 
case of Nos. 44 and 47, the salt-soluble product found may possibly 
be attributed to the slight amount of lactic acid formed in the 
milk before it was heated, or it may be that neutral paracasein 
itself is slightly soluble in salt-solution. There is some basis for 
this latter supposition, for, in the case of milk taken directly from 
a cow and immediately etherized and made into curd, these con- 
ditions excluding ali possible acid formation, there still appears 
to be a slight solubility of the neutral paracasein in dilute 
salt-solution. In the case of Nos. 49 and 50 somewhat more salt- 
soluble product is found than in Nos. 44 and 47. This is undoubt- 
edly due to the effect of the carbon dioxide used, even so weak 
an acid probably having some limited tendency to form with para- 
casein a salt-soluble product. 
OCCURRENCES OF THE SALT-SOLUBLE PRODUCT IN NORMAL CHEDSE. 
In the many normal cheddar cheeses thus far examined by us, 
this salt-soluble substance is always found. The amounts vary, 
but the factors causing the variations have not been fully studied 
yet. For example, the amount of milk-sugar retained in the cheese 
is one cause of such variations; likewise those conditions affecting 
the quantitative conversion of milk-sugar into lactic acid. Then, 
again, we have not yet obtained satisfactory control of all the 
details of the quantitative estimation of this salt-soluble product. 
Its amount varies also with the age of a cheese. In cheese fresh 
from press, that is, about 24 hours old, we have found that from 
4) to 78 per ct. of the total nitrogen is in the form of the sait- 
soluble substance, and the amount diminishes more or less with 
advance of age in the cheese, as illustrated by the figures in 
Table IT. 
