EXPERIMENT STATION BULLETINS. 



335 



A B 



Illustration 4. 



ting in the milk, A being improper. Then tlie pressure of the finger is 

 removed and the millv is allowed to run slowly down the side of the neck 

 into the bottle. Great care should be taken not to lose a drop of milk 

 in the transference as that would lessen the accuracy of the test. It is 

 not intended that every trace of milk should be removed from the pipette 

 because allowance for what remains is made in its construction, for while 



17.5 cc. is the required amount for the test, the pipette is graduated to 



17.6 cc. 



Adding the Acid. — 



In adding the acid, care should be taken that it does not pass directly 

 through the milk, as it may then produce a charred fat. The acid should 

 pass down the side of the neck and the bottle should be turned slowly, 

 so that any milk adhering will be carried along. 



Mixing the Milk and Acid. — 



The milk and acid should be mixed at once with rotarj^ motion and 

 not shaken up and doAvn. The up and down motion tends to lodge hard 

 particles of curd in the neck of the bottle, which causes an inaccurate 

 test. 



Revolving the Test Bottles.— 



The bottles are placed in the tester and whirled after mixing. It is 

 not necessary that this should take place at once; it may be delayed for 

 24 or 48 hours without harm. It is better, however, in case of delay, to 

 warm the contents of the test bottles to 160° -180° F. before proceeding 

 with the test. 



