Testing Milk and Its Products. 



are one-half of the ordinary size, and the test bottles are 

 made in two pieces, with a detachable narrow graduated 

 stem (see Fig. 27). The machine is substantially made 

 of cast iron; it is provided with a very satisfactory speed 

 indicator which shows at any time the num- 

 ber of revolutions at which the bottles are 

 being turned. The accompanying illustra- 

 tions show the apparatus used in the Eussiau 

 test. When the directions for operating the 

 test are followed closely, the results obtained 

 are accurate and very satisfactory. 



83. Bartlett's modification. Bartlett 1 pro- 

 posed a modification of the method of pro- 

 cedure in the Babcock test, which aims to 

 simplify the manipulations. 20 cc. of acid 

 are added, instead of 17.5 cc., and the bottles 

 filled with the milk-acid mixture are left 

 standing for not less than five minutes and 

 then filled with hot water to within the scale; 

 the bottles are then whirled for five minutes 

 at the regular rate (52). 



In the experience of the authors the modi- 



FIG. 27. Test _ 



bottle used in fication can not always be depended upon to 



the Itussian 



test. give satisfactory results. When published it 



was tried by each of the one hundred students in the 

 Wisconsin Dairy School; while some of these operators 

 obtained a clear separation of fat, and results that com- 

 pared favorably with those made by the regular Babcock 

 test, others failed to obtain correct results with the 

 method as modified. It is not known that the modifica- 



Maine experiment station, Bull. No. 31 (S. S.). 



