348 ELEMENTS OF AGRICULTURE 



(7) After adding the acid to the milk, shake the bottle thoroughly 

 until the contents become quite dark in color. 



(8) After using the pipette, wash it thoroughly, preferably in 

 hot water. This will tend to prevent the transmission of disease germs 

 from the mouth of one person to another, should any such germs 

 be present. 



(9) The tester should be firmly fastened to a solid bench or table. 



(10) The person operating the machine should give his or her 

 whole attention to it, and not allow his fingers or clothing to get in 

 the path of the bottle cups. 



(11) Remove all objects from the vicinity of the tester. This will 

 prevent their being hit by the bottle cups when the machine is in 

 motion. 



(12) If acid is spilled upon anything, pour on plenty of water, 

 and then add some alkali, such as lime or baking soda, to neutralize 

 the acid. 



(13) Do not leave the acid bottle uncorked. 



(14) Keep all glassware perfectly clean. 



(15) After washing the glassware, rinse it thoroughly in clean 

 water to remove soap powder. The soap powder and the acid form a 

 violent chemical reaction. 



75. To Determine the Amount of Solids in Milk. 



Weigh a sample of milk. Evaporate to dry ness and weigh again. 

 Determine the per cent of dry matter. Fill out the following table: 



Weight of dish 



Weight of dish and milk 



Weight of dish and evaporated milk 



Weight of dry matter 



Per cent of dry matter in milk 



Per cent of solids not fat (per cent of dry matter minus per 

 cent of fat) 



76. Comparison of Methods of Cream Separation. 



Materials. Milk-testing outfit as for No. 74, but with special 

 bottles for skimmed milk; skimmed milk from a cream separator; 

 skimmed milk that stood in shallow pans, and some that stood in long 

 cans. 



Determine the per cent of fat left in the skimmed milk in each case. 

 If a cow produces 6,000 pounds of milk in a year, and if butter-fat is 



