The protoxide of lead, the protoxide of tin, the hydrate of peroxide of iron, the hydrate of oxides of copper and nickel, oxide of bismuth, combine with hematine, and colour it blue with more or less of a violet cast.
Hematine precipitates glue from its solution in reddish flocks. This substance has not hitherto been employed in its pure state; but as it constitutes the active principle of logwood, it enters as an ingredient into all the colours made with that dye stuff.
These colours are principally violet and black. Chevreul has proposed hematine as an excellent test of acidity.
HEMATITE; (Fer Oligiste, Fr.; Rotheisenstein, Germ.) is a native reddish-brown peroxide of iron, consisting of oxygen 30·66; iron 60·34. It is the kidney ore of Cumberland, which is smelted at Ulverstone with charcoal, into excellent steel iron.
HEMP; (Chanvre, Fr.; Hanf, Germ.) is the fibrous rind of the bark of the cannabis sativa, which is spun into strands or yarn for making ropes, sail-cloth, &c. It is prepared for spinning in the same way as [flax], which see. Hemp-seed contains an oil which is employed for making soft soap, for painting, and for burning in lamps. See [Oils].
Importation of undressed hemp for home consumption; and amount of duty, in
| 1837. | 1838. | 1837. | 1838. | |
|---|---|---|---|---|
| Cwts. | 596,994·3 | 667,017 | £2487 | £2780 |
HEPAR; which signifies liver in Latin, was a name given by the older chemists to some of those compounds of sulphur with the metals which had a liver-brown colour. Thus the sulphuret of potassium was called liver of sulphur.
HEPATIC AIR; [sulphuretted hydrogen gas].
HERMETICAL SEAL, is an expression derived from Hermes, the fabulous parent of Egyptian chemistry, to designate the perfect stoppage of a hollow vessel, by the cementing or melting of the lips of its orifice; as in the case of a glass thermometer, or matrass.