

BY DR. LAUDER BRUNTON. 527 



exists in the fresh milk of the carnivora, and occasionally in 

 that of the cow and goat. 



Specific Gravity. The specific gravity may be taken by 

 the specific gravity bottle or by a hydrometer. Before using 

 either, the milk should be well shaken and air-bubbles removed, 



With a view to the detection of adulteration by water, a 

 special hydrometer is used, which is known as Quevenne's 

 lacto-densimeter. It is furnished with a scale indicating 

 specific gravities from 1042 to 1014. The highest specific 

 gravity of milk yet observed is 1040 to 1041, and the average 

 specific gravity of milk mixed with 50 per cent, of water is 

 1014 to 1016. The instrument is graduated for use at 15 C., 

 and when employed at a different temperature, a correction 

 must be made in the specific gravity indicated by it. Tables 

 for this purpose are to be found in Gorup-Besanez's Zoochemie, 

 3d edition, p. 468. The quantity of water mixed with a 

 sample of milk may be approximately estimated by the sub- 

 joined tables. . 



The specific gravity of milk, with the cream thoroughly 

 mixed with it by shaking, is first ascertained, and if the result 

 is doubtful, another observation is made after the cream has 

 been removed. 



Table for estimating the quality of milk by its specific 

 gravity before the removal of the cream: 



Specific Gravity. 



1033 to 29 = Pure milk. 



1029 " 26 = Milk with 10 per cent, of water. 



1026 "23 = " 20 " " 



1023 " 20 = " 30 " " 



1020 " 17 = " 40 " ". 



lOH " 14 = " 50 " " 



Table for estimating the quality of milk from which the 

 cream has been removed, by its specific gravity : 



Specific Gravity. 



1037 to 1033 = Pure milk. 



1033 " 1029 = Milk with 10 per cent, of water. 

 1029 " 1026 + " 20 " " 



1026 " 1023 = " 30 " " 



1023 " 1020 = " 40 " " 



1020 " 1016 = " 50 " " 



**]/79. Constituents of Milk. Casein. Casein closely 

 resembles alkali-albuminate 4 in its characters. It is not pre- 



1 Casein is usually regarded as identical with alkali -albumiuate. The 

 recent researches of Hoppe-Seyler and Lubavin on its digestion in gas- 

 tric juice, tend to show that it consists of an albuminous, in combina- 

 tion with a non-albuminous, organic body. 



