CHAPTER IX. 



VOLUMETRIC AND INDIRECT ESTIMATION OF FAT. 



FOR the estimation of fat in a rapid manner, with an accuracy 

 sufficient for the milk control, a centrifugal method must be used. 

 The Leffmann-Beam, and the acido-butyronietric methods, will 

 be described in detail. 



The Leffniann-Beam Method and Modifications, Leff- 

 mann and Beam, realising that the time of whirling necessary in 

 Babcock's method, which consisted in treating the milk with an 

 equal volume of strong sulphuric acid, and separating the fat 

 by centrifuging, was a serious objection, experimented with 

 a view to shortening this. They finally decided on the use 

 of amyl alcohol as a means of assisting the fat to rise, and 

 thereby were enabled to reduce the time of whirling.* The 

 method is usually employed in conjunction with the Beimling 

 machine. 



The method has been subjected to a close investigation by the 

 author, and is of considerable accuracy. 



The Beimling Machine. This consists of a cast-iron frame- 

 work carrying a vertical spindle ; on this is a small bevelled cog- 

 wheel, which engages a larger bevelled cog-wheel on a horizontal 

 spindle turned by means of a handle. In the larger machines 

 a second spindle and set of cogs is introduced (Fig. 14). 



On the top of the vertical spindle two, three, or six arms 

 extending radially are fixed. To the ends of each of these are 

 pivoted one or usually two cups, in which the bottles are placed. 



When the handle is turned, the cogs cause the spindle and the 

 arms carrying the cups to rotate. For one turn of the handle, 

 the vertical spindle turns eleven times. Centrifugal force causes 

 the cups to assume a horizontal position when rotating, and they 

 return to the vertical when the machine is at rest. 



* It was stated in the first edition that the same idea was independently 

 worked out at the Vermont Experiment Station ; but it appears that this 

 was not correct, and was based on a misunderstanding. 



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