THE CHEMISTRY OF THE KITCHEN. 363 



impossible ; yet we do not receive and appropriate it directly 

 from the atmosphere, the great storehouse of nitrogen, but 

 from organic compounds containing it under various chemi- 

 cal relations, as found in the substance of our foods. 



Milk and eggs present the most perfect type of all our 

 alimentary materials. They contain all the elements nec- 

 essary for the growth and nutrition of the body. Milk is 

 essential to the young of all mammalia, including man, and 

 should be administered to the human infant in a pure state, 

 without sophistication of any kind, except a little salt. 



Of foods rich in nitrogen, are meats of all kinds, — except 

 fats, — fish, milk, eggs, cheese, beans, pease, cereal grains and 

 nuts. These must be subjected to the digestive processes of 

 the stomach and bowels, disintegi"ated and changed into a 

 highly soluble material called albuminose or peptone, which, 

 acted upon by chemical forces in contact with living tissues, 

 and absorbed into the circulation, metabolized, and in some 

 mysterious way, by many changes, made to contribute to 

 the maintenance of life and energy. 



The fats and oils are non-nitrogenous, composed of carbon, 

 hydrogen and a small per cent, of oxygen ; they are obtained 

 from animal and vegetable sources. 



Fats are not digested in the stomach. The pancreatic 

 secretion converts them without chemical change in the 

 intestine into a fine emulsion, which is absorbed into the 

 circulation through the lactcals, and is parti}-" saponified in 

 the alkaline blood and partly oxidized in respiration, being 

 one of the chief sources of animal heat, holding in this rela- 

 tion the highest place over all other alimentary materials. 



It is also by selective cell action stored in the cellular tis- 

 sues that envelop the body under the skin and surround the 

 muscles, giving — when not in excess — a shapely form and 

 rotundity to the person, and, as a non-conductor of heat, 

 promoting warmth and comfort; and in diseased conditions 

 aftbrding a store of material to be absorbed for purposes of 

 nutrition, when the consumption and digestion of food is in- 

 sufficient for the needs of the body. It is found in brain, 

 muscle, blood and bone, and is a very important — yes, indis- 

 pensable — element in the animal economy. 



The carbo-hydrates, starch and sugar, form another most 



