varieties of milk and their constituents will indicate generally their dietetic value.
| Specific Gravity. |
Solids. | Proteids. | Fats. | Carbohydrates. | Salts. | Water. | |
| Human milk | 1.027 | 12.60 | 2.29 | 3.81 | 6.20 | 0.30 | 87.40 |
| Cow's milk | 10.32 | 12.83 | 3.55 | 3.69 | 4.88 | 0.71 | 87.17 |
| Mare's milk | 1.035 | 9.21 | 2.00 | 1.20 | 5.65 | 0.36 | 90.79 |
| Asses' milk | 1.026 | 10.40 | 2.25 | 1.65 | 6.00 | 0.50 | 89.60 |
| Goat's milk | 10.32 | 14.30 | 4.30 | 4.78 | 4.46 | 0.75 | 85.71 |
| Buffalo's milk | 10.32 | 18.60 | 6.11 | 7.45 | 4.17 | 0.87 | 81.40 |
Value of Milk.—From no other substance, solid or fluid, can so great a number of distinct kinds of aliment be prepared as from milk; some forming food, others drink; some of them delicious, and deserving the name of luxuries; all of them wholesome, and some medicinal; indeed, the variety of foods that seems capable of being produced from milk appears to be almost endless.
BUTTER.
In England butter has been made from time immemorial, though the art of making cheese is said not to have been known to the ancient Britains, and to have been learnt by them from the Romans. The taste of butter is peculiar, and very unlike any other fatty substance. It is extremely agreeable when of the best quality, but its flavour depends much upon the food given to the cows.
Butter, with regard to its dietetic properties, may be regarded as a combination of neutral fats mixed with water and small quantities of casein and salts. Its average proportion is as follows: Fat, 78 to 94; curd, 1 to 3; water, 5 to 14; salt, 0 to 7. Butter becomes sooner rancid than other fats, owing to the presence of more or less casein, which, no matter how throughly washed the butter may be, is never completely removed. When fresh it is a very wholesome article of diet; but it should be quite free from rancidity. If slightly salted when it is fresh, its wholesomeness is not at all impaired; but should it begin to turn rancid, salting will not correct its unwholesomeness. When salt butter is put into casks, the upper part next to the air is very apt to become rancid, and this rancidity is also liable to affect the whole cask.
Different Butters.—Fresh butter comes to London from nearly all the south, east, and south-eastern counties, also from Cheshire, Yorkshire, Devonshire and Wales. The Irish butter sold in London is nearly all salted, but is generally good. Brittany butter is in good repute all over Europe, America, and even India; but no country in the world is more successful in the manufacture of this article,
