The Bdbcock Test. 



45 



FIG. 18. Pip- 

 ette points 



A, proper con- 

 struction; B, 

 undesirable 

 construction 



this thin film has been found to weigh about one-tenth 

 of a gram; consequently 17.6 cc. has been adopted as the 

 capacity of the pipette used for delivering 

 18 grams of milk. 



For convenience in measuring the milk, 

 the shape of the pipette is of importance. 

 The mark on the stem should be two inches 

 or more from the upper end of the pipette. 

 The lower part should be small enough to 

 fit loosely into the neck of the test bottle, 

 and not contracted to a fine hole at the 

 point; the point should be large enough to 

 allow a quick emptying of the pipette 

 (Fig. 18). 



49. Fool Pipettes. Soon after the Babcock test began to be 

 generally used at creameries as a method of paying for the milk, 

 a creamery supply house put on the market a 20 cc. milk-meas- 

 uring pipette, which was claimed to show the exact butter 

 value of milk, instead of its content of butter fat, as is the case 

 in using the ordinary 17.6 cc. pipette. A 20 cc. pipette will 

 deliver 2.4 cc. more milk than a 17.6 cc. pipette, (or 13.6 per 

 cent.), and the results obtained by using these pipettes will, 

 therefore, be about 13.6 per cent, too high. In considering the 

 subject of Overrun (214) it is noted that the excess of butter 

 yield over the amount of fat contained in a certain quantity of 

 milk will range from about 10 to 16 per cent., or on the average 

 about 12 per cent. 20 cc. pipettes may, therefore, give approx- 

 imately the yield of butter obtained from a quantity of milk, 

 but as will be seen, this yield is variable, according to the skill 

 of the butter maker and according to conditions beyond his 

 control; it cannot therefore be used as a standard in the same 

 manner as the fat content of the milk. Similar 22 cc. pipettes 

 were also sent out. These pipettes created a great deal of con- 

 fusion during the short time they were on the market, and 



