238 PRINCIPLES AND PRACTICE OF MILK HYGIENE 



1.825 at 15 C. and amyl alcohol. The test is made as 

 follows : The milk and the chemicals should be at a tem- 

 perature of 15 C. ; 10 c.c. of sulphuric acid are measured 

 with the acid pipette and placed in the bottle. The point 

 of the pipette should be passed obliquely through the 

 opening of the bottle until it comes in contact with the 

 side of the bottle, when the acid is allowed to flow slowly 

 out. Care should be taken that no acid is deposited in 

 the spiral grooves on the inner side of the opening. After 

 thoroughly mixing the milk, 11 c.c. are drawn up into 

 the proper pipette and placed in the bottle with the 

 same precautions, the milk being permitted to flow 

 slowly down the side of the bottle so that it will not mix 

 with the acid. Then 1 c.c. of amyl alcohol is placed in 

 the bottle in the same manner with the alcohol pipette. 

 The three fluids should be arranged in three distinct 

 layers. The bottle is closed with the rubber stopper and 

 the fluids are mixed by slowly raising first one end of the 

 bottle and then the other, permitting the fluid to flow in 

 and out of the neck. This is continued until a perfect 

 solution is obtained. The rubber stopper should be 

 forced in sufficiently to raise the fluid to the zero mark 

 on the scale in the neck and it should be held in place 

 with the thumb while the bottle is being shaken. This 

 latter precaution is taken to prevent the stopper from 

 coming out, although this is not likely to occur if it is 

 properly inserted. The bottle should be placed in a 

 water bath at a temperature of 60 to 65 C. (140 to 

 150 F.), with the stopper downward and the water 

 covering the entire bottle, until it is centrifugalized. This 

 will not be necessary, however, when only one or two 

 samples are being tested. If a hand centrifuge is used 

 the whirling must be continued 10 minutes, but with a 



