VARIATIONS OF MILK CONSTITUENTS I7I 



calculated amount; (4) in 2 cases the calculated per 

 cent exceeded that found by the chemical method to 

 the extent of 0.23 and 0.25 per cent. It is thus seen 

 that, taking the entire season's average, 80 per cent 

 of the results by the method of calculation differed 

 from those obtained with the chemical method by 

 less than o.i per cent. The results given below 

 represent the application of the formula in case of herd 

 milk: 



For ordinary purposes, where the strictest accti- 

 racy is not required, the rule can be used with quite 

 satisfactory results, when applied to herd milks 

 within the limits specified, and most of our cheest^- 

 factory milks come within these limits. Of course, 

 it is readily recognized that, when very accurate, 

 results are necessary, only a direct determinaticm 

 of casein by an accurate method can suffice for t)ie 

 purpose ; and, by an accurate method, is meant one 

 which can be relied upon to give results within on^- 

 tenth of one per cent of the truth. 



