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 
