HYDRAULIC PRESS

See Oil , Pre , and Stearine . HYDRIODIC ACID; ( Acide Hydriodique , Fr.; Hydriodsäure , Germ.) is an acid formed by the combination of 99·21 parts of iodine, and 0·79 hydrogen. When pure, it occurs in the gaseous state, but it combines with water like the hydrochloric or muriatic acid gas into a liquid acid. HYDROCHLORIC ACID; the new chemical name of muriatic acid , which see. HYDROGEN; (Eng. and Fr.; Was sers toff , Germ.) an unde compounded gaseous body; the lightest of all ponderable matter, whose examination belongs to chemistry. HYDROMETER; an instrument for ascertaining the specific gravities of liquids. Baumé’s hydrometer, which is much used in France, and other countries of the continent of Europe, when plunged in pure water, at the temperature of 58° Fahr., marks 0 upon its scale; in a solution containing 15 per cent. of common salt, (chloride of sodium) and 85 of water by weight, it marks 15°; so that each degree is meant to indicate a density corresponding to one per cent. of that salt. See Areometer , for comparative tables of hydrometers. HYDRO SULPHURETS; chemical compounds of bases with sulphuretted hydrogen . HYMENŒA COURBARIL; a tree growing in South America, from which the resin animé exudes.