88 



Determination of Fat hy the Lactohutyromeier. 



1. The milk must be thoroughly mixed, by shaking the bottle, 

 or otherwise by agitation with a glass rod, immediately before it 

 is sampled. If it shoxild be sour, it must be neutralized or made 

 slightly alkaline with potash solution. The pipette marked milk 

 is then filled with the milk above the mark, by suction ; it is then 

 quickly removed from the mouth, and the upper opening closed by 

 the slightly moistened forefinger. By slightly decreasing the 

 pressure, the milk may be made to flow out at the bottom. As 

 soon as the surface of the milk becomes even with the upper mark, 

 the pressure of the finger is again increased, and thereby the out- 

 flow stopped. The under end of the pipette is then brought into 

 the mouth of the lactobutyrometer, and the milk allowed to flow 

 out until its surface becomes even with the under mark. 



If an ordinary pipette is used with only one mark, the last 

 drop is removed by blowing it out. 



2. The pipette marked ether is then filled in a similar manner 

 as described above, with pure ether, and its contents are allowed 

 to flow on the milk in the lactobutyrometer, care being taken that 

 the last drop is brought into the apparatus by blowing it out. 



The tube is then closed with a well-fitting cork, and the whole 

 shaken, lifting the cork from time to time, until milk and ether 

 form a uniform liquid. This takes several minutes. 



During this time the water of 40° C. may be prepared. The 

 cylinder containing the water is placed upon a dish upon which 

 some alcohol is poured and ignited. The alcohol is allowed to 

 burn until the water has reached a temperature of from 40 to 

 42° C, which is observed by a thermometer suspended in the 

 water. The alcohol is then quickly extinguished. 



3. "While yet the water is heating, and after the uniform mix- 

 ture of ether and milk has been obtained, the third pipette is filled 

 with alcohol, and the alcohol added to this mixture. The shaking 

 of the tube is then continued, opening the cork from time to time, 

 until all lumps have disappeared, and the precipitate, which has 

 been formed, appears finely flocculent. The lactobutyrometer is 

 then put into the cylinder, filled with water of 40° C. After- 10 

 minutes standing, the fat solution has well separated from the rest, 



