Various European Tests 87 
‘value as those obtained by the use of the pioscope, 
consequently it has never been used to any great 
extent. 
Soxhlet’s method.—In testing milk by this method, 
the fat in a measured quantity of milk is dissolved 
in ether; the specific gravity of the ether solution 
determined, and from this the percentage of fat is 
calculated. The greater the specific gravity of the 
ether solution the greater the percentage of fat, 
and since the difference in the specific gravity of 
fat and ether is considerable, the addition of a 
small amount of fat will perceptibly affect the specific 
gravity, so that the determination is a very delicate 
one. The determination is made in a specially de- 
vised apparatus known as Soxhlet’s Aérometer. It 
has been widely adopted in Germany, but not at all 
in the United States outside of chemical labora- 
tories. 
DeLaval lactocrite.—This is a machine devised by 
the inventor of the centrifugal separator to esti- 
mate the fat in milk volumetrically. The sample 
to be tested is put in a glass tube with an equal 
amount of concentrated acetic acid containing 5 per 
cent of concentrated sulphuric acid, and the mixture 
cheated for. a few minutes, after which it is whirled 
in a centrifugal machine until the fat is brought to 
the center. It is then read off volumetrically. The 
lactocrite gives a very close determination of the 
fat in milk, but it is necessary to have a separator 
frame in which to whirl the apparatus, which makes 
it somewhat expensive. 
