The Fermentations of Milk. 
797 
Average Composition of One Pint of Cow's Milk. 
The specific gravity of milk being 1'032, a pint weighs 20 oz. 
280 grains, and is made up of — 
Per cent. 
870 . 
4-6 . 
40 . 
3-7 . 
0-7 . 
1000 
Oz. Gr. 
. Water 17 419 
. Lactose, or Milk Sugar 0 416J- 
. Casein, an albuminoid substance composed of the 
elements Carbon, Hydrogen, Oxygen, and Nitrogen, 
with a little Sulphur and Phosphorus ; Lactalbumin, 
an albuminoid present in smaller quantity . . 0 361 
. Butter Fat, a mixture of several compound fats, which 
on decomposition yield glycerin together with 
several fatty and allied acids, the best known of 
which are Oleic, Palmitic, Myristic, Laurie, Stearic, 
Capric, Caprylic, Caproic, and Butyric acids . . 0 334 
. Ash, or Mineral Matter, consisting of — 
Phosphoric Acid , . .17 grains 
Chlorine 10 „ 
Combined with the bases — 
Lime , 
Potash . 
Soda , 
Magnesia . 
Oxide of Iron 
63 ... 0 63 
Total . . . . 20 280 
. 12 „ 
. 7i „ 
. n .. 
. trace 
Milk is, of course, a still more complex liquid than the above 
table shows, and contains small quantities of various substances not 
mentioned in it {e.g. citric acid), but it would be foreign to the pur- 
pose of the present paper to enter into more minute details. 
The sugar and mineral matters of milk may be looked upon as 
simply dissolved in the water, but the condition of the fat, casein, 
and albumin has been the subject of endless discussion. 
Changes in the fat appear to take place directly after milking, 
since some of its ingredients, on which the analyst relies in distin- 
guishing true butter from substitutes like margarine and lard — viz. 
those compounds which yield butyric, caproic, and caprylic acids — 
are now shown not to exist in perfectly fresh milk. In this 
respect milk shows a striking resemblance to blood, which begins to 
undergo remarkable changes directly it is withdrawn from the veins. 
The minute globules of butter-fat floating in milk, familiar to 
everyone who has looked at a drop through the tube of a microscope, 
were long thought to be kept from coalescing and solidifying in the 
milk by a thin albuminous skin surrounding each globule. This 
skin has never been demonstrated, and belief in it has now been almost 
abandoned. Babcock has shown that a small amount of a viscous 
substance resembling the fibrin of blood is formed in milk which 
has stood a short time, rendering it a little less limpid ; and this is 
believed to assist in keeping the globules asunder, and in hindering 
