1 66 MAINE AGRICULTURAL EXPERIMENT STATION. 



added, before they are put in the centrifugal machine and 

 whirled. In this way the separation is completed with one 

 whirling and the time required for the second whirling is saved. 



The modifications of the apparatus are: The base portions 

 of the milk and cream bottles are graduated so that no acid 

 measure is required and the base portion of- the cream bottle is 

 reduced in size. 



While working with the Babcock test some months ago it 

 occurred to the writer that separating the fat before adding 

 water was an unnecssary part of the process if the right con- 

 ditions could be brought about and that the hot water might be 

 added directly after mixing the acid and milk together. Accord- 

 ingly, to decide the matter, a series of experiments were con- 

 ducted, resulting in the adoption of the following method, 

 which has been used successfully for the past six months with 

 all kinds of milk and cream. 



METHOD FOR MILK. 



After the milk is mixed by stirring or pouring from one vessel 

 to another, the required amount, 17.6 cubic centimeters, is meas- 

 ured into the test bottle. It is then heated to about 70 degrees 

 Fahrenheit, if not already at that temperature, by setting the 

 bottles in a tank of warm water. Twenty cubic centimeters of 

 sulphuric acid (specific gravity 1.82 to 1.825) are added and the 

 bottle shaken by giving it a rotary motion until the milk and 

 acid are thoroughly mixed. The mixture is then allowed to 

 stand not less than five minutes. No harm is done if it stands 

 longer than five minutes and in fact, occasionally, some kinds 

 of milk have to be given a little more time. After standing the 

 necessary time the bottle is given another gentle shake to mix 

 in and dissolve any particles of curd that may have risen to the 

 surface. Hot water is then added nearly to the uppermost 

 mark, the bottle is put in the centrifugal machine and whirled 

 for five minutes at the rate of 1,000 to 1,200 revolutions per 

 minute. A steam 'turbine machine is best for this purpose but 

 a hand or belt power machine can be used, if hot water is put 

 in the pan to keep the fat melted. After the whirling is com- 

 pleted the percentage of fat can be read off in the usual manner. 



