104 Milk and Its Products 



should be gradually relaxed and the milk allowed 

 to flow out of the lower end drop by drop until 

 the upper edge of the milk rests exactly upon the 

 graduated mark on the side of the pipette. The 

 milk is then transferred to the test bottle, and this 

 should always be done by placing the end of the 

 pipette against the side of the neck of the bottle, 

 relaxing the pressure of the forefinger gently at 

 first, allowing the milk to flow down the side of 

 the neck. If this is not done there is danger that 

 the neck will become clogged, and a part of the 

 milk be blown out .by the escaping air. When 

 all of the milk has flowed from the pipette, the last 

 few drops should be gently blown into the neck of 

 the test bottle. The utmost care must be taken 

 that all of the milk is transferred from the pipette 

 to the test bottle, and none allowed to escape. 



The acid. The next step is the addition of the 

 acid. The acid should be put into the test bottle in 

 such a way that it will rinse down any milk that 

 has adhered to the sides of the neck, and pass be- 

 tween the milk and the' glass in reaching the bot- 

 tom of the bottle. As soon as the acid is added, 

 the milk and acid should be shaken together with a 

 gentle rotary motion until all of the curd is com- 

 pletely dissolved, care being taken that no particles 

 of curd are thrown into the neck of the bottle. 

 The amount of acid used should be about the same 

 in volume as the milk, depending somewhat upon 

 its strength. Ordinary commercial sulphuric acid 

 with a specific gravity of 1.82 will require about 



