54 MILK 
of distinctly different tint from the milk below it. 
Deception has of late been extensively practised 
by a treatment of milk which breaks up the fat 
globules and increases the volume of cream 
formed, so that a slightly skimmed milk will yield 
afair volume of cream. Determination of fat by 
the usual methods will show the neue See 
page 65. 
It has been found that many of the bottles 
used for distribution of milk are not of the capac- 
ity designated on them, but this is a matter of 
police regulation. 
Perservatives.—These are largely used, es- 
pecially in the warmer season, as a substitute for 
refrigeration. Many of them are sold under 
proprietary names which give no indication of 
their composition. Preparations of boric acid 
and borax were at one time the most frequent 
in use, but at present formalin, a 40% solution 
of formaldehyd, has come into favor. Sodium 
benzoate is now in common use as a preservative 
of cider, fruit-jellies, and similar articles, and 
may, therefore, be found in milk. Salicylic 
acid is not so much employed. Sodium car- 
bonate is occasionally used to prevent coagula- 
tion due to slight souring. Fluorids and abrastol 
may be used. A mixture of boric acid and borax 
is more efficient than either alone. The quantity 
generally used is equivalent to about 0.5 gram of 
