THE BAKERS GUIDE

Hydf-acids. Hydro-acids ; a class of acid compounds into which hydrogen enters as the acidifying principle ; as the hydro- chloric, the hydro-cyanic, etc.

Hydr-argyrum (water, silver; so called from its fluidity and colour). Formerly, Argentum vivum. Mercury, or quicksilver.

Hydr-ates. Chemical compounds of solid bodies and water, jgtill retaining the solid form, as sulphur, soap, etc. These are • also termed hydroxures, and hydro-oxidez. When there is more than one atom of water, prefixes are employed, as bin-aqueous, ter-hydrate, etc.

Hydro-chloric acid. An acid consisting of hydrogen and chlorine, and long known under the name of spirit of salt, marine acid, and muriatic acid.

Hydrocyanic acid. An acid consisting of hydrogen and cyano- gen, and commonly called prussic acid. The hydro cyanic acid of J$cheele contains five per cent, by weight of real acid ; that of the Pharmacopoeia contains about two-fifths of the above weight.

Hydrogen (to produce) . A gas formerly termed inflammable air, phlogiston, or phlogisticated air : its present name refers to its forming water \ when oxidated.

Hydro-meter (a measure). An instrument for measuring the gravity of fluids. When floating in liquid, it rises in proportion as the density of the liquid increases ; it is graduated from I'ooo to i*o6o, so as to exhibit at once the specific gravity.

Hydrous. Watery; containing water in its composition.

Hyper (over or above). This prefix is a Greek proposition, denoting excess. In Chemistry, it is applied to acids which con- tain more oxygen than those to which the word per is prefixed.

Hypo. A Greek proposition signifying under \ or deficiency. In chemistry, it denotes a smaller quantity of acid than is found in the compounds to which it is prefixed, as in hypo-sulphuric acid, etc.

Ice. Glades, Solidified water. The temperature at which it is solidified is called the freezing or congealing point, or 32 0 of Fahrenheit. During liquefaction, its temperature is not changed ; And, hence, the heat which it has absorbed is said to have become latent.

Immiscible. Incapable of being mixed.

Incineration (incinero, to reduce to ashes, from cims, a cinder). The reducing to ashes by burning. The combustion jof vegetable or animal substances for the purpose of obtaining their ashes or fixed residue.

Induction. That law by which an electrified body induces in contiguous substances an electric state opposite to its own.