846 THE VARIABILITY OF COWS' MILK, i , 



tion. The variability of the former class of substances is much 

 g-reater than that of the latter. The greatest variation is shown 

 by the values for the percentage of fat. Within 10% of the 

 median, 38% of the results lie. The amount of fat produced, 

 Lliercfore, is less influenced by the amount of milk secreted than 

 are the amounts of the other constituents. 



The percentage of protein is somewhat less variable than that 

 of the fat, although its extreme range is the same. In this ease, 

 42% of the results lie within 10% of the median value. 



The percentage of ash is considerably less variable, as 61% of 

 the results lie within the range specified. 



The percentages of total solids, and of solids not fat are again 

 considerably less variable. In the case of the former values, 79% 

 of the results are within 10% of the median, and in the case of 

 the latter values, 82% of the results are within this range. 



The constituent of milk, the percentage of which is least vari- 

 able, is lactose. Within 10% of the median, 84% of the values 

 for the concentration of this substance lie. 



Among the physical properties estimated, the most variable is 

 the electrical conductivity; 70% of the values of this property lie 

 within 10% of the median. This variability is rather less than 

 that of the ash, but considerably greater than that of the percent- 

 age of lactose. 



The values of the other physical properties determined are 

 much less variable than that of the electrical conductivity. The 

 whole of the results for the values of the density and of the depres- 

 sion of the freezing-point lie within 10% of the median values. 

 The wdiole of the results for the depression of the freezing point 

 lie within 5% of the median, in fact. The molecular concentration 

 of the dissolved substances is, therefore, the most constant pro- 

 perty of milk. 



It should be noted that the variability of the density has been 

 calculated not on the actual values obtained, but on the differences 

 between these values and the density of water, for the reasons 

 stated above. 



The distributions of the above series of values is shown more 



