70 



SCIENCE AND PRACTICE OF DAIRYING. 



If milk is both creamed and watered, and the watering has been 

 checked by the use of the hydrometer, or if the milk is only slightly 

 watered, the original values of (s) and (r) remain unchanged; indeed they 

 are even slightly increased. Generally, however, the values of (.9) and (r) 

 are diminished. The original value of (m) is increased, while that of (/) 

 is very considerably diminished, and that of (t) to a less extent. 



The areometric estimation of fat by Soxhlet's method has been so 

 universally adopted that it is not difficult for anyone to make himself 



familiar with it. Its 

 principle is a very 

 happy one. The fat 

 in a measured quan- 

 tity of milk is dis- 

 solved in ether, and 

 the specific gravity 

 of the ether solution 

 at a certain tempera- 

 ture is determined 

 in an ingeniously 

 constructed appa- 

 ratus. From this the 

 amount of fat in the 

 milk is calculated 

 the higher the spe- 

 cific gravity of the 

 solution, of course 

 the more fat does it 

 contain. As the 

 difference between 

 the specific gravity 

 of fat and ether is 



considerable, far more than, for example, the difference in the specific 

 gravity of milk and water, the specific gravity of the ether is correspond- 

 ingly changed by the addition of even a small quantity of fat. This 

 renders it possible to estimate the percentage of fat in milk with very 

 great delicacy. A greater advantage which it possesses is that it esti- 

 mates, with almost an equal degree of accuracy, the percentage of fat 

 in skim-milk as well as in whole milk. 



In the case of the lactocrit (fig. 26), the coagulated portion of the 

 nitrogenous matter in a measured quantity of the milk, precipitated by 

 continuous boiling of the milk with a mixture of glacial acetic acid and 

 sulphuric acid, is first completely dissolved, and the fatty milk-globules, 



Fig. 26. The Lactocrit. 



