TESTING CREAM BY THE BABCOCK TEST 77 



Sometimes it is well to let the bottles stand a little 

 while after being mixed with the acid, until the mix- 

 ture turns dark, before whirling. 



When the liquid just below the fat-column is milky 

 and the fat looks cloudy and light, exact reading is 

 difficult. In such cases the bottles may be placed in 

 water at 130 to 140 F. for 15 or 20 minutes before 

 whirling, or, if this fails, the fat may be solidified by 

 placing the bottles in cold water after the last whirl- 

 ing and then heated to 130 or 140 F. before reading. 



READING THE PER CENT. OF FAT IN CREAM- 

 TESTING BOTTLES 



In reading the results of a cream test, more care 

 is needed than in testing milk, especially if wide- 

 necked bottles are used in which the finest divisions 

 represent .5 per cent, or more. For accurate work, 

 one should use narrow-necked cream-bottles in which 

 the results can be read to .2 per cent. 



In no case, should there be used in the same cream- 

 ery at the same time different varieties of cream-bot- 

 tles, having necks of widely-varying diameter. It 

 has been shown by Webster ( Bulletin No. 58, Bureau 

 of Animal Industry, Dairy Division, U. S. Dept. of 

 Agr.), that the results obtained with cream-bottles 

 having necks of varying diameters are wide apart, 

 when read in the ordinary manner. This is due to 

 the fact that the depth of the meniscus increases with 

 the diameter of the neck of the bottle. The wider the 

 neck the greater the error, this being in the direction 

 of too high results. 



