THE OLD METHOD OF CREAM-SEPARATION. 109 



by all available means, such as cooling the milk to a low tempera- 

 ture, the observance of the greatest cleanliness in handling the milk, 

 as well as in the rooms where cream-raising is carried out, and by 

 taking care that only pure dry air should be provided in these rooms, 

 and that they should be properly ventilated. 



(5) The currents induced in milk by cooling, especially those 

 moving in a perpendicular direction, should be prevented, or should 

 be reduced to the shortest possible duration. 



The extent to which these requirements are carried out will 

 depend on the amount of fat obtained in a given time from the layer 

 of cream, and the success of the cream -raising. The requirements 

 which demand that the milk, on the one hand, should be kept as 

 warm as possible in order to minimize the amount of resistance, 

 and those, on the other hand, which demand that the milk should 

 be kept as cool as possible in order to lessen lactic fermentation, 

 are contradictory to one another. Since, however, the second 

 requirement is undoubtedly of greater importance than the first, 

 there is no option but to fix the temperature of cream-raising so 

 low that the milk will keep sweet i.e. that on boiling it will not 

 coagulate at least thirty-six hours. Practice has long demonstrated 

 that this is the case with a temperature of 12, or at the most 15 C., 

 provided all precautions as to cleanliness have been observed. This 

 is, therefore, the temperature to be recommended. 



Formerly there was a comparatively large number of different 

 methods of cream-raising in use, each one of which possessed special 

 advantages of its own. The most widely used and the most per- 

 fectly developed was that known as the Holstein method, which 

 originated in Schleswig-Holstein. Now, with hardly an exception, 

 all these methods have become antiquated, and are no longer used in 

 the larger new dairies. All the older methods of cream-raising are 

 at one in requiring that the greatest cleanliness should be observed, 

 and that the milk should be set immediately after milking. They 

 all, including the Swartz and Devonshire methods, prescribe also 

 a certain temperature to which the milk, as it comes from the cow, 

 has to be cooled, and require that milk should be maintained in the 

 further stages of the process at the cream-raising temperature. In 

 other respects they show considerable differences in respect of the 

 temperature to which the milk is raised, the greater or less speed 

 with which the warm milk is cooled to the cream-raising tempera- 

 ture, and the method in which the cooled milk is maintained at the 



