Various European Tests 87 



value as those obtained by the use of the pioscope, 

 consequently it has never been used to any great 

 extent. 



SoxhleVs 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 Aerometer. 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 volume trically. 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 

 heated 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. 



