152 



NORMAL MILK ; ITS ADULTERATIONS, ETC. 



The maximum individual differences varied from + 0'46 to 

 — 0'44, or nearly 0'5 per cent. 



It is seen from the above table that there is a very slight ten- 

 dency for the proteins to be higher when the fat is high, but the 

 tendency is very much less than that indicated by Timpe's formula. 



H. C. Sherman finds that a milk rich in fat is generally rich 

 in protein, the excess of protein above the normal averaging 

 one-third of the excess of fat. 



Variation of Constituents of Solids not Fat. — Vieth 

 gives the average proportion between milk-sugar, protein, and 

 ash in milk as 13 : 9 : 2. 



The author has found that this ratio is marvellously exact, 

 the average being 



Milk-sugar, 52-8 % as against 54-2 calculated from Vieth's ratio. 

 Protein, 37-8 „ 37-5 „ „ 



Ash, 8-3 „ 8-3 



In order to ascertain whether all the constituents of the solids 

 not fat vary directly as the total percentage, or whether an 

 excess or deficiency of solids not fat is due to excess or deficiency 

 of any one constituent, the author has examined a large number 

 Of analyses of milk in which milk-sugar, protein, and ash were 

 determined. On plotting out the average figures for solids not 

 {Eat against each of the constituents, the figures for milk-sugar, 

 protein, and ash lie each in a series of three straight lines. For 

 feach constituent the breaks occur between 8 '8 per cent, and 

 8'9 per cent., and between S'i per cent, and 8'5 per cent., and are 

 jquite well defined. It is suggestive that the one figure is very 

 iiear the average percentage, and the other is almost that adopted 

 as the limit for normal milk, and the figures show that it would 

 be difficult to dilute down a milk high in solids not fat without 

 arousing a strong suspicion that it is watered. Table XX. gives the 

 average figures deduced ; individual samples raay show differences. 



