Cream Testing. 87 



and the fat appears white and cloudy, making an exact 

 reading difficult. Such defects can usually be over- 

 come by placing the test bottles in hot water for about 

 ten minutes previous to the whirling, or by allowing the 

 fat to crystallize (which is done by cooling the bottles 

 in cold water after the last whirling) and remelting 

 it by placing the bottles in hot water. 



The error due to the expansion of the fat in case of 

 excessively hot turbine testers having no openings in 

 the cover as mentioned on p. 36, is especially noticeable 

 in cream testing, where it may amount to one per cent, 

 or more. In order to obtain correct results with such 

 testers, the hot cream test bottles must be placed in 

 water at about 140 P. for some minutes before the 

 results are read off. 



The subject of different methods of reading cream 

 tests have been studied by "Webster and Gray, 1 who 

 conclude that correct results are obtained by taking 

 readings at 120 F., from the bottom to the extreme 

 top of the fat column, deducting four-fifths of the 

 depth of the meniscus from this result and adding .2 

 per cent, to the figure thus obtained. 



96. Eliminating the meniscus in cream tests. The 

 uncertainty concerning the exact point at which the 

 meniscus of the fat column should be read in cream 

 tests has been removed by the use of certain liquids 

 which do not mix with fat but when dropped on top of 



on the results of cream tests is given in bulletin 58, Bur. An. Ind., 

 U. S. Dept. of Agriculture, where a discussion of the influence of dif- 

 ferent temperatures on readings of cream tests will also be found (see 

 96). 



1 Bujl. 58, Bur. An. Ind., U. S. Dept. of Agriculture. See also Mass, 

 rept., 1909, p. 142. 



