MAKING THE TEST. 53 



Blow the milk which remains on the inside of 

 the pipette into the bottle. Next, measure the acid, 

 and pour it carefully into the sample, holding the 

 bottle in a slanting position, that the acid may run 

 along the side of the bottle and under the milk not 

 through it. Mix the acid and the milk by a rotary 

 motion, being careful not to get any curdy matter in 

 the neck of the bottle. When the curd is all dissolved, 

 and the contents are a dark brown color, caused by 

 the burning of the milk sugar and other compounds 

 of the milk, the sample or samples may be placed in 

 the pockets of the machine. It is very important to 

 have an even number of bottles in the machine, and 

 to have them properly balanced. Whirl the samples 

 at full speed for about five minutes, then add the hot 

 water with a pipette, or from a small can having an 

 outlet at the bottom to which is attached a small 

 hose, closed at the lower end with a pinch-cock. A 

 small piece of glass-tubing, drawn to a point and 

 inserted in the rubber, is convenient for filling. Fill 

 the botttles to the eight or ten per cent. mark. Be 

 careful not to run the fat over the top of the bottle, 

 and have sufficient water to float the fat into the 

 scale when it is read. 



When troubled with cloudy readings it is advisable 

 to add the water at two different times, instead of all 

 at once. After adding the water, whirl the samples 

 again for two minutes, when the readings may be 

 made. If testing many samples, especially in a 

 cold room, it is advisable to remove them from the 

 machine to a dish of hot water at a temperature of 

 about 140 degrees. 



