
New York AGRICULTURAL EXPERIMENT STATION. 223 
stearin makes a hard fat. The amount of fat in milk may vary 
from two to ten pounds per hundred of milk, the average amount 
being not far from 3.5 pounds per hundred. Butter contains 
from eighty to eighty-five pounds of fat per hundred, while 
cheese may contain all the way from three pounds of fat per hun- 
dred pounds of cheese, as in skim-cheese, to sixty pounds per 
hundred, as incream-cheese. The averageamount of fat in cheese 
made from normal milk averages thirty pounds. or more per 
hundred. 
3. The solids not fat in milk, cheese, etc., include all the solids 
except the fat, and these are (1st) the nitrogen compounds, chief of 
which are casein and albumen ; (2d) milk sugar, and (3d) ash. 
(1) Casein and albumen are known as nitrogen and nitrogenous 
compounds, because they contain, in addition to other elements 
the element nitrogen, which the other compounds of milk do not 
contain. These nitrogen compounds are often called also albu- 
minoids, because they closely resemble in composition the albu- 
men or white of an egg. They are sometimes called proteids also, — 
The two principal nitrogen compounds or albuminoids in milk 
are casein and albumen and these compounds are the only ones we > 
shall notice in this connection. Casein and albumen are of more 
especial interest to the cheese-maker than any other constituents 
in the milk. Of these two compounds, the casein is the more 
important. Casein and albumen differ in their chemical properties 
in two important respects : 
‘ (1st) Albumen is not coagulated or solidified by acids or by 
action or rennet, while casein is coagulated. 
(2d) Albumen is coagulated by heat, while casein is not. 
These properties of casein and albumen have a practical bearing 
upon cheese-making, since by the action of rennet we can coagu- 
late the casein and retain it in the curd, while the albumen passes 
into. the whey more or less completely and is lost to the cheese. 
The amount of casein and albumen together in normal milk may 
vary from below three to over four pounds per hundred, the 
average amount being a little short of 3.5 pounds per hundred. 
(2) Milk Sugar has essentially the same composition as ordin- 
ary cane sugar, but the former is less soluble and less sweet. than 
the latter. Milk sugar is acted upon by certain micro-organisms 
