CHAPTER V. CHEMISTRY OF THE HUMAN BODY. Ultimate and Organic Elements. 1. By the chemical composition of the body, is meant those ultimate elements of which it is made; such as oxygen, carbon, hydrogen, and azote. By the organic composition, we mean the proximate elements, which are formed out of these by the power of the living principle; such as albumen, fibrin, gelatine, &c. 2. The ultimate elements of animal matter have been divided into non-metallic, and metallic substances; the former consisting of oxygen, hydrogen, carbon, azote, phosphorus, sulphur, chlorine, and fluorine; the latter, 1, the bases of the alkalies, viz., potassium, sodium, and calcium; 2, the bases of the earths, magnesium, silicium, and aluminum; 3, the ponderous metals, iron, manganese, and copper.} Of the first class, or the non-metallic substances, oxygen, hydrogen, carbon and azote exist in much the largest proportion, and are in fact the only essential elements of animal matter. 3. All the solids and fluids of the body contain oxygen.) It is essential to all the proximate elements. United with hydrogen, it forms water, which is calculated to constitute nine-tenths of the whole weight of the body. In union with carbon, it forms carbonic acid, which exists in the blood, and is thrown out by the lungs and skin. 3. Oxygen forms with phosphorus, phosphoric acid, which with lime constitutes the earthy portion of the bones; it also exists in some of the secretions. In union with their metalic bases, it forms potash, soda, and lime. It also is a consti. tuent part of albumen, fibrin, gelatine, and mucus. Oxygen is derived partly from the air we breathe, and partly from our food and drinks. It is given off in all the secretions and excretions. The air contained in the swimming bladder of fishes, is pure oxygen. 4. Hydrogen exists in all the fluids and most of the solids, constituting as it does one element of water. In venous blood, it exists in a larger proportion than in arterial blood, which contains more oxygen. In the bile, it is very abundant, and in fat and oil, is one of the essential elements. It is this gas which often causes so much distress in a weak state of the stomach. Hydrogen is introduced into the system by means of food and drinks, and is discharged in the same manner as oxygen 5. (Carbon abounds in the vegetable as well as animal kingdom. In oil, fat, albumen, gelatine, fibrin, and mucus, it always forms a part. In bile, and in venous blood, it exists largely. If we burn a piece of animal substance, what is left is found to be chiefly carbon. We obtain it from our food, and give it off by breathing and the secretions. It is carbon that makes venous blood darker than arterial, and the change from purple to bright crimson which takes place in the lungs, is supposed to be owing chiefly to the fact, that the excess of carbon contained in venous blood is discharged by respiration 6. Azote exists in large quantities in all animal matter. It also exists to some extent in a few vegetables, but it is an essential element in animal substances. It is more abund. ant in fibrin, of which the muscular flesh is chiefly formed, than in any other portions of the body, though it is found in the brain and nerves. The peculiar smell of burning animal matter is owing to azote. When animal substances putrefy, it combines with hydrogen, and forms ammonia or hartshorn 7. Azote is chiefly taken into the system by means of animal food. It is also taken into the blood by respiration, as it forms a constituent part of the atmosphere. This, however, is denied by some chemists. It is discharged from the system in the same manner as oxygen, hydrogen, and carbon; though chiefly through the kidneys. 8. Phosphorus exists both in animal and vegetable substances. Nearly every part of animal bodies contain it, though it is found more abundantly in the bones. It generally exists in combination with oxygen, forming phosphoric acid. It is discharged mostly through the kidneys. The spontaneous combustion of human bodies, of which we have some well-attested cases of drunkards, is supposed to be owing to an accumulation of phosphorus in the system, from some unknown cause. 9. Sulphur is always united, in animal substances, with other elements, as soda and potash. It is found in albumen, in the hair and nails, and in muscular flesh. It is given off by the intestines and by the skin. 10. Chlorine is found in most of the animal fluids com. bined with hydrogen. This forms hydrochloric acid. In the blood it is combined with soda and potash. It is found also in the gastric juice, in sweat, milk, saliva, &c. 11. Potash exists more abundantly in plants than in animals. It is, however, contained in the blood, bile, urine, sweat, milk, &c. 12. Soda is more abundant in animals than plants. It exists in the same fluids in which potash is found; also in bones and muscular flesh. It is always combined with some acid. 13. Lime forms a large part of the bones, in union with phosphoric or carbonic acid. Silex exists in human hair, and in some of the secretions. Magnesia is contained in bones, and in some animal fluids, as milk. It is also found in the brain. Iron forms the colouring principle of the red globules of the blood, and is therefore pretty extensively found in animal bodies. 14. The organic or proximate elements of the body are formed from the ultimate elements already described) We cannot explain their formation on any chemical or mechanical laws, but refer them solely to the influence of the vital forces. 15. These proximate elements are mostly formed from a combination of oxygen, carbon, hydrogen, and azote, and are divided into two classes, acids and oxyds) 16. The acids found in the human system are the acetic, oxalic, the benzoic, and the uric The three first are also found in the vegetable kingdom, and are composed of oxygen, hydrogen, and carbon. When these organic elements are made of three simple elements, they are called ternary oxyds; such are sugar, resin, and the fixed and volatile oils. 17. Milk contains a considerable quantity of sugar. It can be obtained from whey by evaporating it slowly to the consistence of a syrup, and then allowing it to cool. It may then be purified by the white of an egg, or albumen, and crystalized again. It has a different taste from the sugar of the cane. 18. The bile contains a peculiar resin. Fat and the marrow of the bones contain fixed oils. But the most important compounds of the body are albumen, fibrin, gelatine, mucus, andxists in the body, both in a solid and fluid 19. form Combined with water it forms the white of eggs; hence its name. It exists most abundantly in the serum, but is found in all the fluids of the body. It is transparent, without colour, taste, or smell, and coagulates by heat, acids, and alcohol 20. Solid albumen is also a white and tasteless substance. It forms the basis of the nerves and brain, and is contained in the skin, hair, nails, glands, and vessels. Tumours and wens are mostly composed of albumen. It is composed of Carbon 52 parts; Oxygen 23 parts; Hydrogen 7 parts; Azote 15 parts. 21. (Fibrin is the basis of muscular flesh and enters largely into the formation of the blood, chyle, and lymph. It is owing to the presence of fibrin that blood coagulates when removed from the body. Fibrin is a solid, white substance, of a fibrous structure, destitute of smell and taste, and insoluble in water. 22. Fibrin may be obtained by washing the thick part of the blood with cold water, and thus separating the colouring matter, or the red globules. It differs from albumen by possessing the property of coagulating at all temperatures. Fibrin is composed of Carbon 43 parts; Oxygen 19 parts; Hydrogen 7 parts; Azote 19 parts. It contains more azote and less oxygen than albumen. 23. Gelatine is found in none of the fluids of the human ody. It is, however, found in nearly all the solids. It is known from all the other animal principles by its readily dissolving in warm water, forming a kind of jelly) When dry, it forms a hard, shining, brittle substance, called glue. This is mostly prepared from the skins and hoofs of animals, by boiling them in water, and then evaporating the solution. Isinglass is obtained from the sounds of the sturgeon, and is a very pure gelatine. 24. Gelatine exists largely in the skin, cartilages, ligaments, tendons, and bones, and it forms the basis of the cellular tissue, As it does not exist in the blood, it is probably a modification of albumen. It is composed of Carbon 47 parts; Oxygen 27 parts; Hydrogen 7 parts; Azote 16 parts. 25. It appears that gelatine contains less carbon than albumen, by 5 or 6 per cent., and a larger proportion of oxygen in the same ratio. Now, if we suppose, that near the skin, and in the various tissues of the body, the albumen of the blood gives off a portion of its carbon, a part of which |