Sugar of milk, . . 4'67 



Asii, . . . 0-60 



280 MANUAL OF AGEICULTUEE. 



of the proximate feeding compomicls should be the principal in- 

 ofredient in the food of each class of animals. Substances, ac- 

 cordingly, rich in albuminous matter, should constitute the food 

 of hard-working animals, that fibrin and albumin may be applied 

 to their muscular wants. To such as it is desired that thej 

 should be quickly fattened, and which undergo only sufficient 

 exercise to maintain good health, are freely giyen compounds 

 known to contain much fat-forming material. To young grow- 

 ing animals a fair proportion of both kinds of food is offered, 

 and such substances in addition as hold saline bodies, like phos- 

 phate of lime, which avail for the building up of the bones. 

 Milk affords a safe criterion of the food constituents appropriate 

 to young animals. It is the food nature provides for them, and 

 none other can be so perfect. According to Way, the average 

 composition of cow's milk is — 



Water, . . . 87-02 



Butter,. . . 3-23 



Casein, . . 4-48 



And of its ash (from two analyses by Haidlen, of 1000 lb. of 

 milk, each of separate cows) — 



lbs. lbs. 



Phosphate of lime, . . . .2-31 3*44 



f, magnesia, .... 0*42 064 



,, peroxide of iron, . . . 0-07 0"07 



Chloride of potassium, .... 1*44 1"83 



„ sodium, .... 0*24 0*34 



Free Boda, . . . . . .0-42 0-45 



The oleaginous bodies contained in the fluid are broken up into 

 minute globules or cells ; and when new milk is allowed to 

 settle in any suitable vessel, these rise to the surface, and form 

 the cream. When the cream is removed, it leaves the skimmed 

 milk almost entirely devoid of oily matter. The albuminous 

 matter, or casein, is held in solution by the fluid, by means of 

 some one of the alkaline bodies ; the latter becomes neutralised 

 by the addition of certain acids, whereupon the casein coagulates, 

 and this curd, by pressure and suitable treatment, becomes con- 

 verted into cheese. The remaining fluid, or whey, contains the 

 sugar and the inorganic salts. The natural curdling of milk 

 takes place when lactic acid, CgH^Og, its peculiar acid, is 

 formed ; and its presence is evidenced by the fluid becoming 

 sour in taste. Johnson says : — " The change which takes place 

 when milk becomes sour is easily understood. Under the influ- 

 ence of the casein, the elements of a portion of the milk-sugar 

 are made to assume a new arrangement, and the sour lactic acid 

 is the results. There is no loss of matter ; no new elements are 

 called into play ; nothing is absorbed from the air, or given off 

 into it ; but a simple transposition of the elements of the sugar 

 takes place, and the new acid compound is produced. These 



