DOMESTIC ECONOMY, HYGIENE, DIETETICS. 



371 



our individual tastes, and, so far as possible, 

 we should take our meals arnid pleasant social 

 surroundings. In great crises that call for un- 

 usual exertion, we should rest the stomach, 

 that for the time the brain may work the 

 harder ; but the deficiency of nutrition ought 

 always to be supplied in the first interval of 

 repose." 



CHEMICAL COMPOSITION OF 

 THE HUMAN BODY. 



The human body is composed of the follow- 

 ing elements, all of which are found also in 

 the food provided by nature, or in air or 

 water, and all must be supplied, day by day, 

 or some bad results are sure to follow : 



Oxygen, a gas, in quantity sufficient to 

 occupy a space equal to 750 cubic feet, 



Hydrogen, a gas, in quantity sufficient to 

 occupy 3000 feet, which with oxygen, 

 constitutes water, the weight of the 

 two indicating nearly the necessary 

 amount of water 



Carbon, constituting fat, and used also 

 for fuel to create animal heat 



Nitrogen, which constitutes the basis of 

 the muscles, and solid tissues, and 

 which is supplied by that part of the 

 food which we shall denominate Ni- 

 trates 



Phosphorus, the physical source, of vitali- 

 ty, and the most important of the 

 mineral elements, will represent the 

 whole class which we shall denominate 

 the Phosphates 



Calcium, the metallic base of lime, which 

 is the base of the bones 



Fluorine, found combined in small quanti- 

 ties in bones 



Chlorine, constituting, with sodium, com- 

 mon salt, found in the blood 



Sodium, the base of all the salts of soda. . 



Iron, which is supposed to give color to 

 the blood . 



Potassium, the base of all the salts of pot- 

 ash 



Magnesium, the base of magnesia, and 

 magnesian salts 



Silicon, the base of silex, which is found 

 in the hair, teeth, and nails 



LB. oz. OR. 



ill 



The elements of a man weighing 154 Ibs. 



Classification of Food. Food may be 

 divided into three classes. That class which 

 supplies the lungs with fuel, and thus furnishes 

 heat to the system, and supplies fat or adipose 

 substance, etc., we shall call Carbonates, car- 

 bon being the principal element ; that which 

 supplies the waste of muscles, we shall call 

 Nitrates, nitrogen being the principal element ; 

 and that which supplies the bones, and the 

 brain, and the nerves, and gives vital power, 

 both muscular and mental, we shall call the 

 Phosphates, phosphorus being the principal ele- 

 ment. These last might be- subdivided into 

 the fixed and the soluble phosphates, the 

 fixed being a combination principally with 

 lime to form the bones, and the soluble being 

 combinations with potash and soda, to work 



the brain and nerves ; but our analyses as yet 

 are too imperfect to allow a subdivision, and 

 as all the mineral elements are more or less 

 combined with each other, and all reside to- 

 gether in articles of food, we shall include 

 all mineral elements under the term Phos- 

 phates. 



The waste, and consequently the supply, of 

 these three classes of elements is very differ- 

 ent, four times as much carbonaceous food 

 being required as nitrogenous, and of the 

 phosphates not more than two per cent, of the 

 carbonates. Altogether, the waste of these prin- 

 ciples will average in a man of moderate size, 

 with moderate heat, more than one pound in a 

 day, varying very much according to the amount 

 of exercise and the temperature in which he 

 lives. These elements must all be supplied in 

 vegetable or animal food, not one being allowed 

 to become a part of the system unless it has been 

 first organized with other elements of food, in 

 some vegetable, or in water, or the atmosphere ; 

 but being appropriated by some animal, remain 

 organized and adapted to the human system, 

 so that animal and vegetable food contain the 

 same alements in the same proportion and 

 nearly the same chemical combinations, and 

 are equally adapted to supply all necessary el- 

 ements. 



In Animal Food, 



In Vegetable Food, 



'The Carbonates 

 j are furnished in 



The Nitrates in 



Fat. 



Albumen, 

 Fibrin, and 

 Casein. 



fThe Carbonates ) Sugar, 



5 Starch, and a 

 are furnished in ) little Fat. 



The Nitrates in 



Gluten, 

 Albumen, 

 and Casein. 



The Phosphates in both animal and vege- 

 table food are found inseparably connected 

 with the nitrates, none being found in any of 

 the carbonates, and generally in the propor- 

 tion of from two to three per cent, of all the 

 principles in vegetable, and from three to five 

 in animal food. 



The Carbonates of both animal and vegeta- 

 ble food are chemically alike fat, sugar, and 

 starch, all being composed of carbon, oxygen, 

 and hydrogen, and in about the same chemical 

 combinations and proportions. 



The Nitrates, also albumen, gluten, fibrin, 

 and casein, are alike in chemical combina- 

 tions and elements, being composed of nitro- 

 gen, oxygen, and hydrogen, and a little carbon 

 not digestible. These simple bodies are not, 

 however, capable of being assimilated and con- 

 verted into tissue ; they must be previously 

 combined, primarily by the vegetable kingdom. 



