Rural School Leaflet. 655 



skimmed milk will slowly separate into curds and whey. When the whey 

 amounts to more than half of the quantity of milk used, it should be 

 removed by pouring through a cloth strainer. The casein remains in the 

 cloth. It is one of the principal constituents of cheese. 



For the albumen. — Slowly heat the whey to 160° F. It will become 

 somewhat cloudy and soon a soft jelly-like substance will collect on the 

 surface. This is albumen which was coagulated by the heat. It is 

 similar to the albumen or white of an egg. It should be separated by 

 straining. This constituent is not used in the manufacture of butter or 

 the ordinary varieties of cheese. 



For the sugar. — A small quantity of whey which has been freed from 

 its albumen is placed in a clean porcelain dish with a large bottom (as a 

 saucer) and this is warmed, care being taken not to burn it. It may be 

 warmed in an oven with the door partly open. When the water has 



Fig. 4. — The constituents of a quart of milk. 



evaporated, a dry substance remains. This is about seven-eighths milk- 

 sugar and one-eighth ash. It is not practicable to separate the sugar in 

 pure form from the ash. Sugar is not present in large quantity in either 

 butter or cheese. 



For the ash. — A part of the mixture of sugar and ash is placed in a 

 dish which will withstand high heat, or on the stove cover, and allowed to 

 burn as long as it will. The small amount of incombustible matter left is 

 milk-ash. It is not an important constituent of either butter or cheese. 



The amounts of the different constituents in different milks varies 

 somewhat, but the following shows the percentage composition of average 

 milk and aljout the quantity of each constituent in one quart, which 

 weighs 2. 1 5 pounds : 



