118 SCIENCE AND PRACTICE OF DAIRYING. 



well as the weight of the cream obtained, and to calculate what 

 percentage of the entire fat in the milk was obtained in the cream. 

 This percentage number he called the cream-yielding coefficient. 

 This method has been followed by others. 



As the cream-yielding coefficient depends not only on the per- 

 centage of fat in the skim-milk, but also on that of the whole milk, 

 and on the relative weight of the cream and the skim-milk, it affords 

 an exact indication of the yield of cream in different cases, provided 

 the milk used in the experiments has a similar percentage of fat, 

 and that the relative weights of the cream and the skim -milk 

 remain constant. 



The calculation of the cream-raising coefficient is very simple, as the 

 following example will indicate : 



100 Ibs. of milk containing 3*4 per cent of fat yielded 20 Ibs. of cream 

 and 80 Ibs. of skim-milk, containing -5 per cent of fat. 



The total quantity of milk contained, therefore, 3 '4 Ibs. of fat. 



In the skim-milk there remained = -4 Ib. of fat. 



100 



In the cream, therefore, there was 3 Ibs. of fat. 



These 3 Ibs. make l: 9 = 88'24 per cent of the total quantity of 

 the 3-4 Ibs. of fat. 



The cream-raising coefficient is therefore 88'24 per cent; that is, 88-24 

 per cent of all the fat contained by the milk was yielded in the cream. 



In the case of a sample of milk containing the average quantity of 3 f 4 

 per cent of fat, and yielding on an average 15 per cent of cream, in the 

 Holstein method, and allowing 36 hours for cream-raising, the cream- 

 raising coefficient throughout the year would average 84 per cent. The 

 skim-milk, therefore, would contain in this case '64 per cent of fat, and if 

 97 per cent of the fat in the cream were converted into butter containing 

 84 per cent of fat, then from 100 Ibs. of milk 3 '3 Ibs. of butter would 

 be obtained, or for every Ib. of butter obtained, 30 '3 Ibs. of milk by 

 weight are used. Under similar circumstances, it will be found in practice 

 in the ice method of creaming, when the cream-raising period lasts for 12 

 hours, that the cream-raising coefficient on the average of a year will 

 amount to 74 per cent. In such a case the skim -milk would contain 

 T04 per cent of fat, and for every 100 Ibs. of milk 2 -91 Ibs. of butter 

 would be obtained. That is, 3 4 -3 7 Ibs. of milk are used for every pound 

 of butter produced. 



In all the older methods, creaming was effected through the 

 influence of gravity, which is practically always the same. It is 



