The bases are also a large class. They are mostly rare substances, not familiarly known: Morphia, obtained from Opium; Quinia, from Quinine; Nicotine, from Tobacco, are illustrations.
Composition of organic and inorganic bodies contrasted.—There are more than fifty elementary substances found in the inorganic kingdom, but only four, commonly speaking, in the organic: these four are Carbon, Hydrogen, Nitrogen, and Oxygen.
Some organic bodies,—oil of turpentine, naphtha, etc., contain only Carbon and Hydrogen; many others, such as sugar, gum, alcohol, fats, vegetable acids—Carbon, Hydrogen, and Oxygen. The Nitrogenous bodies, so called, containing Nitrogen in addition to the other elements, are principally substances derived from animal and vegetable tissues, such as Albumen, Caseine, Gelatine, etc.; Sulphur and Phosphorus are also present in many of the Nitrogenous bodies, but only to a small extent.
Organic substances, although simple as regards the number of elements involved in their formation, are often highly complex in the arrangement of the atoms; this may be illustrated by the following formulæ:—
| Starch | C24H20O20 |
| Lignine | C24H20O20 |
| Cane Sugar | C24H22O22 |
| Grape Sugar | C24H28O28 |
Inorganic bodies, as already shown, unite in pairs,—two elements join to form a binary compound; two binary compounds produce a salt; two salts associated together form a double salt. With organic bodies however the arrangement is different,—the elementary atoms are all grouped equally in one compound atom, which is highly complex in structure, and cannot be split up into binary products.
Observe also, as characteristic of Organic Chemistry, the apparent similarity in composition between bodies which differ widely in properties. As examples take Lignine, or cotton fibre, and Starch,—each of which contains the three elements united as C24H20O20.
Mode of distinguishing between Organic and Inorganic matter.—A simple means of doing this is as follows:— place the suspected substance upon a piece of Platinum-foil, and heat it to redness with a spirit-lamp: if it first blackens, and then burns completely away, it is probably of organic origin. This test depends upon the fact, that the constituent elements of organic bodies are all either themselves volatile, or capable of forming volatile combinations with Oxygen. Inorganic substances, on the other hand, are often unaffected by heat, or, if volatile, are dissipated without previous charring.
The action of heat upon organic matter may further be illustrated by the combustion of coal or wood in an ordinary furnace;—first, an escape of Carbon and Hydrogen, united in the form of volatile gaseous matter, takes place, leaving behind a black cinder, which consists of Carbon and inorganic matter combined; afterwards this Carbon burns away into Carbonic Acid, and a grey ash is left which is composed of inorganic salts, and is indestructible by heat.