OUTLINE OF MILK- ANALYSIS. 15 



of milk wrung out of the udder at the termination of the 

 milking. These are richer in cream than the average mass 

 of the milk, and they have a much lower density than 

 average milk. 



I have myself examined strippings with a specific gravity 

 of 1.020, and a specific gravity of 1.025 is by no means un 

 common. In the instance of strippings of the latter gravity, 

 I found the percentage of solids to be 18.74. 



Now, if we all knew concerning a sample of milk was that 

 its gravity was 1.025, we might with equal reasonableness 

 conclude, either that it contained fifteen or twenty per cent, 

 of extraneous water, or that it was surcharged with cream. 



If, by adding fat to milk, the specific gravity is lowered, it 

 follows that by substracting fat (i. e., by skimming), the 

 specific gravity is raised ; and hence the explanation of the 

 reaching of the high M. mark by skimming. 



A certain trick of the milk trade is fostered by the employ 

 ment of the lactometer. The milk is partially denuded *of 

 cream (accomplished conveniently by adding a certain quan 

 tity of skimmed milk to the fresh milk), and thereby raised 

 in gravity. That being accomplished, it is dosed with water, 

 and its gravity is thereby lowered to the normal standard. 



Let no one think that he would discover such a trick by 

 making an estimation of cream ; for watered milk throws 

 up its fat in the form of cream more perfectly than un watered 

 milk. 



Another objection relative to the lactometer (which, how 

 ever, pertains to the application of the hydrometer to organic 

 fluids generally) is drawn from the circumstance that a com 

 paratively small change in density corresponds to a great 

 change in composition. Making total abstraction of the 

 difficulty and uncertainty dependent on the cream, and re 

 garding milk as a solution of caseine and milk-sugar, it will 

 be seen that whereas the specific gravity of water rises only 



