Accordion

A small musical instrument, with DICTIONARY THINGS INFORMATION Acid. [L,. acetum, vinegar; acid us,sour.] The most common of the vegetable acids, famil¬ iar to all as the sour principle in vinegar. It occurs in the juice of many plants, and in some animal secretions; but on the large scale it is prepared from damaged wines, by the ferment a¬ tion of malt, or by the destructive distillation of wood. Pure acetic acid is prepared by the dry distillation of wood. The pure acid has a sour taste and a pungent smell, is poisonous, and burns the skin. In the arts it is used as a mordant in calico-printing, and in the preparation of certain varnishes. It is also used as a condiment and in medicine. The salts of acetic acid are called acetates, the most important of them being ace¬ tate or sugar of lead. [U. acetum, vinegar.] A substance composed of carbon and hydrogen and of remark¬ able powers. It is not a new discovery but has only lately been produced in large quantities from carbide of calcium, a product of the electric furnace. When water is thrown on this sub¬ stance it gives off acetylene gas. It was found about 1895, that this gas, when burned in a suit¬ able burner, would give the brightest light of any known gas. When placed under strong pre ure acetylene becomes a liquid, and the gas which arises from this is burned in suitable lamps, yielding a light twelve times as bright as that of ordinary coal gas. But this new light has not come into much use, for there is danger of ex¬ plosion. Acetylene has other uses, for a great many chemical substances can be made from it, belonging to what are called the hydrocarbons. [Gk. achromatos, colorle .] Free from color (applied to lenses, telescopes and microscopes); transmitting light without decom¬ posing it into its primary colors.—Achromatic lens, a combination of two di imilar substances, as crown and flint gla , so arranged that the chromatic aberration produc d by the one is corrected by the other, and light pa es unde¬ composed. 579 3 4