MANUAL OF GENERAL AGRICULTURE. 101 



Allow the pipette to drain into the test bottle and blow 

 into the upper end of it to discharge the last drop of 

 milk in the pipette into the test bottle. 



The best results will be obtained by having the 

 samples of milk and also the acid at the temperature of 

 60 F. 



Find the ground or frosted part on the body of the 

 bottle and place on it your initials; or better still ask 

 the teacher to give you a number corresponding to a 

 number by the side of one of the receptacles in the tester. 

 Always use the same number and the same bottle in order 

 to avoid confusion. 



(d) Adding the Acid. After the milk has been meas- 

 ured into the test bottles, the acid should be added. This 

 may be done at once or the milk may be allowed to stand 

 in the test bottles for a number of days without changing 

 the results. Fill the acid measure up to the mark (17.5 

 c.c.) with sulphuric acid of the specific gravity between 

 1.82 and 1.83. To pour the acid into the test bottle, 

 the bottle should be placed in an inclined position so 

 that the acid will flow down the side of the test bottle 

 and not drop through the body of the milk in the bottle. 

 By observing this precaution, charring of the milk is 

 avoided and also spilling out of the acid. If the acid 

 has been properly added, there will be distinct layers of 

 acid and milk in the test bottle, without any black layers 

 mixed between them. 



(e) Mixing the Milk and Acid. This is done by giv- 

 ing the test bottle a combined rotary and shaking mo- 

 tion, being careful not to allow any curd to get into the 

 neck of the bottle. The shaking of the bottle should be 

 continued until all the particles or clots of curd are en- 

 tirely dissolved. The liquid will then be a dark brown 

 color and of a high temperature, due to the chemical ac- 

 tion of the acid on the milk. The object of adding the 

 acid is to dissolve all the solids in the milk, except the 

 fat which is left in suspension in the liquid. 



Caution. The acid is very corrosive and should not 

 be allowed to get upon the person or clothes. If any 



