21 



Chemical Analysis of Milk. 



GENERAL RULES. 



For the examination of milk one must be enabled to commence 

 the examination at once, and to carry it through without loss of 

 time. It is, therefore, absolutely necessary that the laboratory bo 

 well supplied with all the apparatus mentioned at the end of this- 

 book, in such quantity that no time is lost by preparations of any 

 kind. 



The first process taken in hand consists in the coagulation of 

 the milk. "When this is in progress the determination of the 

 solids and salts is commenced. After the iiltration from the co- 

 agulated albuminates is iinished, and while the milk is drying on 

 the water bath, the physical properties and the reaction of the milk 

 are determined. 



Milk should be thoroughly mixed before samples for the various 

 determinations are removed. For exact analyses it is also necessary 

 not only to measure the milk, but to verify and correct the figures 

 obtained by measurement by actual weighing in a covered vessel. 



A careful and exact record of all data concerning the analysis 

 is indispensable. Measures should be given in cubic centimeters 

 and weights in grammes ; and for the measurement of the temper- 

 ature, the Celsius or Centigrade thermometer should be employed. 



In case that the temperature has been observed on. a Fahren- 

 heit thermometer, the corresponding degrees of the Celsius ther- 

 mometer may be found by the table given on page 18. For higher 

 temperatures than those given in this table, the corresponding 

 temperature on the Centigrade thermometer may be found by 

 deducting 32 from the degrees read, dividing the rest by 9, and 

 multiplying by 5. For instance : 



(185—32) X 5 



185° F = = 85° C. 



9 



and, vise versa, we may convert Celsius degrees into degrees 

 Fahrenheit by the following equation : 



85 X 9 

 85° C. = -h 32 = 185° F. 



