47 



The common cream vats used in American creameries up to 

 six or eight years ago were the rectangular tin vats hung in a 

 wooden, watertight tank, which allow for a space with hot or cold 

 water. Some of them are provided with space into which to put 

 ice. Some are made U shaped and these are better still, and 

 others, the twin vats, have two narrow vats in one jacket. (Fig. 

 33). It is evident that a large body of cream is only slowly 

 heated or cooled in these and that constant stirring is necessary, 



(Fig. 33) 



hence we find that many makers are obliged often against their 

 better conviction to use ice directly in the cream. If perfectly 

 pure ice (made from distilled water) is used, and it is crushed 

 fine and kept stirred until dissolved or nearly so, there is no harm 

 done. But pond and stagnant river ice is a fearful source of all 

 kinds of contamination and, if it is left in large lumps without 

 stirring, the cream will be unevenly ripened, so that this system 

 of cooling should be discouraged. 



The fact is that the question of giving the creamery butter- 

 maker complete and quick control of the temperature in his cream 

 has not as yet been solved satisfactorily, but since the introduction 

 of refrigerator machines a very great step ahead has been taken. 

 Thus the cream room itself can now be kept at a uniform tempera- 

 ture of 50 to 60 deg. (instead of 70 to 90) and there the tempera- 

 ture of a large vat of cream will not rise or fall much during the 

 night. 



As to the cooling in the vat various systems have been tried. 

 In one creamery they tried to cool it with the air by having the 

 vats without jacket, but experience taught them what they might 

 have known, that air does not conduct the heat (or cold) as well 

 as water. 



Others have placed ammonia coils in the water space of the 



