MILK. 201 



been fully explained, for when the summer heats produce 

 a most active chemical action in all. organic matter, 

 this unstable substance, milk, becomes very troublesome 

 to the dairyman. Milk consists of a solution of caseine 

 in a sweet liquid, which is somewhat alkaline. The av- 

 erage four per cent of sugar and the four per cent of 

 caseine are both held in solution in the milk, wliich also 

 contains a sufficient quantity of free soda to make it dis- 

 tinctly alkaline. This free soda enables the caseine to 

 remain in solution, and when it is taken up by any acid 

 in the milk, and rendered inert, or neutral, the caseine 

 is at once precipitated, and the milk curdles, because of 

 this precipitation or separation of the caseine. The min- 

 -eral matter of milk consists of the following substances : 



m 1,000 POUNDS OF MILK THERE ARE OF 



li>2C7ids. Pounds. 



Phosphate of lime -2.31 to 3.41 



Phosphate of magnesia 43 to .G-i 



Phosphate of oxide of iron ....07 to .07 



Chloride of potassium .1.44 to 1.83 



Chloride of sodium 24 to .34 



Free soda 43 to .45 



Total.-.. 490 to 6.77 



All this matter is neutral or chemically inert or inac- 

 tive excepting the free soda, which is at all times ready 

 and eager to combine with any acid which may exist in 

 the milk. 



Sugar is a very unstable substance, and is liable to change 

 under very little persuasion. A saccharine solution very 

 easily oxidizes and changes to acid at the expense of the 

 carbon which is combined with the oxygen, and produces 

 carbonic acid, which escapes, leaving an acid liquid in- 

 stead of a sweet one. Really, the sugars and some acids 

 derived from them are compounds of carbon and water. 

 Thus common sugar consists of twelve atoms of carbon 

 and eleven atoms of water, and milk sugar of twelve 

 atoms of carbon and twelve of water, while acetic acid, 

 made by the fermentation of cane sugar, consists of two 



