34 SCIENCE AND PRACTICE OF DAIRYING. 



correct results, provided, of course, that the constant numbers which occur 

 in them are correspondingly changed. The author's practical experience 

 confirms in a very satisfactory manner the accuracy of the results deduced 

 from the formulae given above, especially (3) and (4), and it has been thus 

 shown that the constants of the formulae correspond very closely to the 

 conditions prevailing in Germany and England. 



Should the numbers obtained in various places, however, despite 

 accurate calculation, not exactly correspond to those directly found, the 

 average value for n must be calculated from equation (2) and used in the 

 following equation: 



(6) t= nxl ' 07527 " 1 x/i n X 100x *- 100 



n 1 n 1 s 



Taking n as equal to 1*6, and working out the equation, formula (6) is 

 converted into formula (3). 



By denoting the percentage of nitrogenous matter, milk-sugar, and 

 mineral matter in milk by x, y, and z respectively, and the respective 

 specific gravities by o-j, <r 2 , and o- 3 , we obtain the following formula : 



x x <r 2 x <T 3 + y x <TI X 0s + 2 x <TI x a-i 



As is easily shown, n is constant, either if <r 1 =o- 2 =<r 3 , or if the respective 

 ratio of x, y, and z be the same for all kinds of milk. Neither the former nor 

 the latter is exactly the case. Nevertheless the values of <r v <r 2 , and <r 3 

 differ very little, as a close examination will show. The respective ratio 

 of x, y, and z is also not unknown. There is always more milk-sugar 

 than nitrogenous matter in ordinary milk; but the value of z in milk of 

 different origin only varies between *6 and *8 per cent. That the one 

 condition as well as the other is fulfilled, to a certain extent at any rate, is 

 obvious, since through the combination of both of these favourable circum- 

 stances a very approximate constancy of value for n can be obtained. 



The specific gravity m, of the total solids, is obtained from the equa- 

 tion 



/7\ ,_ **? 



x*~(100x-100)' 



For obtaining the value of t (equation 3), and m (equation 7), the 

 author has devised tables, by means of which the value of t can be obtained, 

 by a simple addition, and that of m through subtraction and division. 



12. Colostrum (first milking, beastings, beistyn). Colostrum, 

 which is the liquid secreted by the milk-glands both before and 

 immediately after calving, possesses peculiar chemical and physical 



