HEAT n.
in fire, the sun's rays, mechanical action, chemical combination, etc., becomes directly known to us through the sense of feeling. In its nature heat is a mode if motion, being in general a form of molecular disturbance or vibration. It was formerly supposed to be a subtile, imponderable fluid, to which was given the…
HEPTANE n.
everal isometric hydrocarbons, C7H16, of the paraffin series (nine are possible, four are known); -- so called because the molecule has seven carbon atoms. Specifically, a colorless liquid, found as a constituent of petroleum, in the tar oil of cannel coal, etc.
HORNBILL n.
Any bird of the family Bucerotidæ, of which about sixty species are known, belonging to numerous genera. They inhabit the tropical parts of Asia, Africa, and the East Indies, and are remarkable for having a more or less horn-like protuberance, which is usually large and hollow and is situated on the upper side of the b…
HORNED a.
having a pair of elongated tufts of feathers on the head. Several distinct varieties are known; as, the Arctic, Western, dusky, and striped horned owls, differing in color, and inhabiting different regions; -- called also great horned owl, horn owl, eagle owl, and cat owl. Sometimes also applied to the long-eared owl.…
HYDROGEN n.
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…