REGULATION OF CREAM AND SKIM-MILK IN SEPARATORS. 147 



1892. If a percentage of fat in the skim-milk of '25 per cent be regarded 

 as satisfactory, certainly distinctly more milk can be creamed per hour 

 at these high temperatures than at 30 C., and in this fact another 

 advantage is to be found. 



74. The Regulation of the Relative Quantity of Cream and Skim- 

 milk in the Use of Separators. With all separators a larger or 

 smaller quantity of cream in proportion to the skim-milk can be 

 obtained at the will of the worker. All that has to be done is to 

 increase or diminish the amount of the flow of the milk to the 

 drum. In this, however, the degree of creaming varies, a thing 

 that ought not to be permitted in well-regulated work. For this 

 reason, the quantity of cream obtained from an equal supply of 

 milk ought to be able to be regulated at will. In the drums of all 

 separators, with the exception of the Victoria separator, the neces- 

 sary apparatus is supplied. In the separators of Burmeister and 

 Wain, arranged for power use, the regulation is effected during the 

 flow, and in the other separators such precautions as are necessary 

 must be taken while the drum is at rest, in most cases before the 

 commencement of the creaming. If the speed of the flow of milk 

 does not change, it does not exercise the slightest influence on the 

 percentage of fat in the skim-milk, whether 15, 20, or 25, or still 

 higher percentages of cream be taken. It is only when the quantity 

 of cream is less than 10 per cent of the total weight of the milk, 

 that the cream is imperfectly separated in the case of some separators. 

 The cream is obtained thicker and richer in fat the smaller the 

 quantity. It is not to be recommended to take less than 10 per cent 

 of the weight of milk, while over 20 per cent should only be taken 

 if there is some special object, since skim-milk would be lost. As a 

 rule it is desirable to obtain 15 per cent to 20 per cent of cream. 



If there be indicated by (/) and (/j) the percentage composition of the 

 fat of milk and skim-milk, and by (r) and (b) the relative proportions of 

 cream and butter obtained from 100 parts of milk, the percentage of fat 

 in the cream (a) will be exactly found by the following equation: 



100 x (/-.ft)- 



~~ + " 



and approximately by the equation: 



*=* 



B 



