Blood consists of water, sugar, fat, albuminous substances, chloride of sodium, chloride of potash, fluoride of lime, silica, iron, lime, magnesia, soda and potash. The latter are combined with phosphoric, carbonic and sulphuric acids.

The salts of soda predominate in the blood plasma, while those of potash are found especially in the blood corpuscles. Sugar, fat, and the albuminous substances are the so-called organic components of the blood, while the above-named salts and water constitute its inorganic components. Sugar and fat are compounds of carbon, hydrogen and oxygen, while the albuminous substances contain in addition sulphur and nitrogen.

Sulphur, carbon and phosphorus are not present within the organism in a free state, but combined with organic substances.

Sulphur and carbon are found in the albumen, carbon it. the carbo-hydrates like sugar, starch and in the products incident to metamorphosis of organic substances. Phosphorus is contained in the lecithins and in the nucleins. The sulphur of the albumen is oxidized by the oxygen of the inspired air, forming sulphuric acid which combines with the bases of the carbonates, forming sulphates and setting free carbonic acid.