18 BUTTER-MAKING. 
small amount of alcohol, formic, acetic, and succinic acids are 
said to be normal accompanying by-products also. These 
by-products may also partially result from the breaking down 
of some of the other milk components. 
As milk-sugar is in perfect solution, it follows the water 
of milk, and in cheese-making nearly all of it passes into the 
whey. Commercially and chemically it is prepared from 
whey. It is a white, not very sweet powder, and is used for 
medicinal purposes to dilute pure, powerful drugs. It is also 
used extensively in the preparation of modified milk. 
Ash.—The ash of milk is present in very small quantities, 
and when viewed from such a standpoint it may first seem 
to be of small importance. On account of the effect of the 
mineral constituents upon the properties of milk, it is one 
of the most important components of the milk. It consists 
partly in solution, and partly in suspension. Babcock main- 
tains that about one-third of the usual ash constituents is in 
suspension, and that they consist chiefly of lime phosphate. 
All of the minerals in milk consist chiefly of potash, lime, 
soda, magnesia, and iron, combined with phosphoric, hydro- 
chloric, sulphuric, and carbonic acid. Calcium phosphate 
constitutes about one-half of all the ash constituents. They 
are named above, in order, according to the extent in which 
they occur in milk. 
Gases of Milk.—These do not normally exist in milk to 
such an extent as to enable chemists to determine them quan- 
titatively, but they are of great importance, owing to the 
effect they have upon the quality of the milk, viewing it in 
the commercial sense. 
Gases in milk may be divided into two classes according to 
their origin; namely, (1) those imparted to milk before milk- 
ing and (2) those which are formed and absorbed in milk 
later. 
(1) When freshly drawn milk has a characteristic cowy 
smell, which seems to be normal to all fresh milk. These 
gases are very volatile, and by cooling and aerating milk (differ- 
