HALOGENE; is a term employed by Berzelius to designate those substances which form compounds of a saline nature, by their union with metals; such are [Bromine], [Chlorine], [Cyanogene], Fluorine, [Iodine]. Haloid is his name of the salt thereby formed.
HANDSPIKE, is a strong wooden bar, used as a lever to move the windlass and capstan in heaving up the anchor, or raising any heavy weights on board a ship. The handle is smooth, round, and somewhat taper; the other end is squared to fit the holes in the head of the capstan or barrel of the windlass.
HARDNESS (Dureté, Fr.; Härte, Festigkeit, Germ.); is that modification of cohesive attraction which enables bodies to resist any effort made to abrade their surfaces. Its relative intensity is measured by the power they possess of cutting or scratching other substances. The following table exhibits pretty nearly the successive hardnesses of the several bodies in the list:—
| Substances. | Hardness. | Sp. Grav. |
|---|---|---|
| Diamond from Ormus | 20 | 3·7 |
| Pink diamond | 19 | 3·4 |
| Bluish diamond | 19 | 3·3 |
| Yellowish diamond | 19 | 3·3 |
| Cubic diamond | 18 | 3·2 |
| Ruby | 17 | 4·2 |
| Pale ruby from Brazil | 16 | 3·5 |
| Deep blue sapphire | 16 | 3·8 |
| Ditto, paler | 17 | 3·8 |
| Topaz | 15 | 4·2 |
| Whitish topaz | 14 | 3·5 |
| Ruby spinell | 13 | 3·4 |
| Bohemian topaz | 11 | 2·8 |
| Emerald | 12 | 2·8 |
| Garnet | 12 | 4·4 |
| Agate | 12 | 2·6 |
| Onyx | 12 | 2·6 |
| Sardonyx | 12 | 2·6 |
| Occidental amethyst | 11 | 2·7 |
| Crystal | 11 | 2·6 |
| Cornelian | 11 | 2·7 |
| Green jasper | 11 | 2·7 |
| Reddish yellow do. | 9 | 2·6 |
| Schoerl | 10 | 3·6 |
| Tourmaline | 10 | 3·0 |
| Quartz | 10 | 2·7 |
| Opal | 10 | 2·6 |
| Chrysolite | 10 | 3·7 |
| Zeolite | 8 | 2·1 |
| Fluor | 7 | 3·5 |
| Calcareous spar | 6 | 2·7 |
| Gypsum | 5 | 2·3 |
| Chalk | 3 | 2·7 |
HARTSHORN, SPIRIT OF; is the old name for water of [ammonia].
HATCHING OF CHICKENS; see [Incubation, Artificial].
HAT MANUFACTURE. (L’art de Chapelier, Fr.; Hutmacherkunst, Germ.) Hat is the name of a piece of dress worn upon the head by both sexes, but principally by the men, and seems to have been first introduced as a distinction among the ecclesiastics in the 12th century, though it was not till the year 1400 that it was generally adopted by respectable laymen.
As the art of making common hats does not involve the description of any curious machinery, or any interesting processes, we shall not enter into very minute details upon the subject. It will be sufficient to convey to the reader a general idea of the methods employed in this manufacture.
The materials used in making stuff hats are the furs of hares and rabbits freed from the long hair, together with wool and beaver. The beaver is reserved for the finer hats. The fur is first laid upon a hurdle made of wood or wire, with longitudinal openings; and the operator, by means of an instrument called the bow, (which is a piece of elastic ash, six or seven feet long, with a catgut stretched between its two extremities, and made to vibrate by a bowstick,) causes the vibrating string to strike and play upon the fur, so as to scatter the fibres in all directions, while the dust and filth descend through the grids of the hurdle.