246 PRINCIPLES AND PRACTICE OF MILK HYGIENE 
DETERMINATION OF THE SPECIFIC GRAVITY OF THE SOLIDS 
The specific gravity of the dry milk solids can be cal- 
culated from the per cent. of total solids and the specific 
gravity of the milk according to the following formula: 
2S st 
st —(100 s—100) 
m represents dry milk solids, s specific gravity and t total solids. 
m 
The specific gravity of the dry solids of normal whole 
milk varies from 1.31 to 1.86. Skimming milk increases 
the specific gravity of the milk solids. 
DETERMINATION OF THE PER CENT. OF FAT IN THE 
TOTAL SOLIDS 
The per cent. of fat in the total solids can be calcu- 
lated from the per cent. of fat and of total solids in the 
milk according to the following formula: 
f 
p=--X 100 
p represents per cent. of fat in total solids, f per cent. of fat in the milk and 
t per cent. of total solids. 
The per cent. of fat in the total solids varies from 
20 to 34. It is decreased by skimming. 
DETERMINATION OF THE DEGREE OF ADULTERATION 
When it is possible to compare a sample of adulter- 
ated milk with a sample of the same milk collected under 
conditions which exclude the possibility of adulteration, 
the extent of the adulteration may be determined approxi- 
mately by the following formulas of Béhmlander: 
m=2 x w—-W 
fR 
