160 MILK [x 



Another admirable method for determining fat is 

 by the lactocrit, an apparatus devised by Dr. de 

 Laval. A measured quantity of milk is placed in a 

 glass tube, an equal amount of concentrated acetic 

 acid, containing 5 per cent of concentrated sulphuric 

 acid, is then added, and the mixture heated for a few 

 minutes at boiling temperature. The effect of the 

 acid is to dissolve the caseous matter, which retards 

 the movement of the fatty globules. The tube is 

 then placed in a specially constructed centrifugal 

 apparatus, and the mixture is separated by centrifugal 

 force, the depth of the layer forming a measure of its 

 amount. 



Another method is that devised by Leffmann and 

 Beam. A quantity of milk is treated in a bottle with 

 a graduated neck with one-fifth of its volume of a 

 mixture of equal parts of amyl alcohol and strong 

 hydrochloric acid. Strong sulphuric acid is then 

 added to the mixture in nearly equal quantity, and 

 the whole is well mixed. The bottle is then placed 

 in a centrifugal separator, which is rotated for one or 

 two minutes. The fat layer, which collects in the 

 neck of the bottle, is then read off. 



5. Determination of the Specific Gravity. The 

 determination of the specific gravity of milk must be 

 reckoned as one of the most important of all the 

 tests to which it can be subjected. Alone, it is no 

 doubt apt to be misinterpreted. In milk we have 



