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A stone of a fine grit, or a slab, as of metal, covered with an abrading substance or powder, used for sharpening cutting instruments, and especially for setting razors; an oilstone. Tusser. Hone slateSee Polishing slate. -- Hone stone, one of several kinds of stone used for hones. See Novaculite.

Any substance, as a easting of iron, a piece of worm-eaten wood, or of triple, etc., perforated with cells like a honeycomb. Honeycomb moth (Zoöl.), the wax moth. -- Honeycomb stomach. (Anat.) See Reticulum.

A sweet, saccharine substance, found on the leaves of trees and other plants in small drops, like dew. Two substances have been called by this name; one exuded from the plants, and the other secreted by certain insects, esp. aphids.

The horny substance or case that covers or terminates the feet of certain animals, as horses, oxen, etc. On burnished hooves his war horse trode. Tennyson.

consisting of a shallow iron box, containing kerosene or coated with tar or other sticky substance, which may be mounted on wheels.

A chemical substance formed in one organ and carried in the circulation to another organ on which it exerts a stimulating effect; thus, according to Starling, the gastric glands are stimulated by a hormone from the pyloric mucous membrane.

ral projection or excrescence from an animal, resembling or thought to resemble a horn in substance or form; esp.:

Composed or made of horn, or of a substance resembling horn; of the nature of horn. "The horny . . . coat of the eye." Ray.

A bed of earth heated by fermenting manure or other substances, and covered with glass, intended for raising early plants, or for nourishing exotics.

A bitter, brownish yellow, amorphous substance, extracted from vegetable mold, and also produced by the action of acids on certain sugars and carbohydrates; -- called also humic acid, ulmin, gein, ulmic or geic acid, etc.

The pellucid substance, present in cells in process of development, from which, according to some embryologists, the cell nucleous originates.

A derivative of urea, C3H4N2O2, obtained from allantion, as a white, crystalline substance, with a sweetish taste; -- called also glycolyl urea.

of the golden seal (Hydrastis Canadensis), and extracted as a bitter, white, crystalline substance. It is used as a tonic and febrifuge.

A compound formed by the union of water with some other substance, generally forming a neutral body, as certain crystallized salts.

tate of being, a hydrate. Water of hydration (Chem.), water chemically combined with some substance to form a hydrate; -- distinguished from water of crystallization.

A gaseous element, colorless, tasteless, and odorless, the lightest known substance, being fourteen and a half times lighter than air (hence its use in filling balloons), and over eleven thousand times lighter than water. It is very abundant, being an ingredient of water and of many other substances, especially those o…

zyme, or chemical ferment, which acts only in the presence of water, and which causes the substance acted upon to take up a molecule of water. Thus, diastase of malt, ptyalin of saliva, and boiling dilute sulphuric acid all convert starch by hydration into dextrin and sugar. Nearly all of the digestive ferments are hyd…

Pertaining to, or depending upon, both liquid and gaseous substances; as, hydropneumatic apparatus for collecting gases over water or other liquids.

A white crystalline substance, C6H4(OH)2, obtained by the reduction of quinone. It is a diacid phenol, resembling, and metameric with, pyrocatechin and resorcin. Called also dihydroxy benzene.

ime of Archimedes is due to Stevinus. Hallam. Hydrostatic balance, a balance for weighing substances in water, for the purpose of ascertaining their specific gravities. -- Hydrostatic bed, a water bed. -- Hydrostatic bellows, an apparatus consisting of a water-tight bellowslike case with a long, upright tube, into wh…