The materials for the food of man, and containing the above elements, are derived from the mineral, vegetable, and animal kingdoms. The vegetable kingdom, however, is the great source of food to man and animals, as it is in the cells of the plant that the elements undergo those chemical changes which fit them for food. The animal can only supply what it obtains from them, and the substances supplied by the animal kingdom as food are identical with those obtained from plants. The FOOD COLLECTION is arranged as nearly as possible in the order of the following CLASSIFICATION, commencing at the _western end_ of the lower gallery. CLASS I. ALIMENTARY OR NECESSARY. Group 1. _Mineral Substances_. Examples: Water; Common Salt; Ashes of Plants and Animals. Group 2. _Non-nitrogenous force-producing Substances_, _incapable of forming Flesh or Muscle_. Examples: Sago, Arrowroot (_Amylaceous_); Sugar, Figs, Dates (_Saccharine_); Animal and Vegetable Fats and Oils (_Oleaginous_). Group 3. _Nitrogenous Substances capable of producing both Flesh and Muscle_. Examples: Eggs (_Albuminous_); Wheat, Flesh (_Fibrinous_); Peas, Cheese (_Caseinous_). CLASS II. MEDICINAL OR AUXILIARY. Group 1. _Containing Alcohol_. Examples: Beers, Wines; Spirits. Group 2. _Containing Volatile Oils_. Examples: Spices and Condiments, as Cloves, Nutmegs, Pepper, Horse-radish, &c. Group 3. _Containing Acids_. Examples: Apples, Oranges, Rhubarb Stalks, Vinegar. Group 4. _Containing Alkaloids_, _which act upon the nervous system as stimulants or sedatives_. Examples: Tea, Coffee, Cocoa; Tobacco, Hemp, Opium. CLASS I.—ALIMENTARY OR NECESSARY. WATER. The first and most essential constituent of food is water. Three fourths of the body is composed of water, and it is by the agency of water that all kinds of food are taken up into the system. Solid food contains large proportions of water, but, in proportion to the dryness of food, water should be added to it, in the form of some kind of beverage. QUANTITIES OF WATER IN 100 POUNDS OF DIFFERENT KINDS OF SOLID FOOD. _Vegetable Food_. lbs. lbs. Cabbage 92 Maize 14 Turnips 87 Peas 14 Carrots 86 Beans 14 Beetroot 83 Lentils 14 Parsnips 79 Buckwheat 14 Potatoes 75 Oatmeal 13 Bread 44 Rye 13 Flour 14 Rice 13 Barley Meal 14 Cocoa 5 _Animal Food_. Milk 86 Lamb 50 Eggs 80 Mutton 44 Fish 78 Cheese 40 Veal 62 Pork 38 Beef 50 Bacon 30