390
BITUMEN".
water. It is thus obtained in Saxony ; and 900 pounds of pyritesyield from 100 to 150 pounds of crude Sulphur , which is further pu-rified by distillation, by which it loses .about one eighth of its weight.—It is then melted and cast in wooden moulds into cylinders, knownin commerce by the name of sulphur or roll-brimstone .—When fur-ther purified by sublimation, it is called sublimed Sulphur or flowersof Sulphur.
The uses of Sulphur in chemistry, medicine, and the arts are nu-merous, important, and sufficiently well known.
Bitumen, especially when a little heated, may be recognised byits peculiar odor, which to many persons is not unpleasant. Somevarieties are liquid, others soft, and others too hard to receive an im-pression from the finger nail, but, at the same time, very brittle. Theliquid and softer varieties yield more or less odor, even when cold.
The spec. gray, of Bitumen is often below 1.00, and never exceeds1 . 20 , unless the specimen be impure. By friction it acquires nega-tive electricity. When liquid, it is sometimes yellowish or brownish,and sometimes limpid and transparent; but the more solid varietiesare black or brown.
It burns easily, yielding a thick smoke, which has a strong, pecu-liar odor, hut not very pungent. There is sometimes a very smallearthy residuumafter combustion. The solid varieties are easily melt-ed, but, when cool, they are very brittle. Bitumen yields little or noammonia by distillation. Its principal ingredients are hidrogen andcarbon. It is insoluble in w'ater and alkohol, but combines with fixedand essential oils. (Mvrrat.)
Bitumen presents several varieties, most of which evidently passinto each other,proceeding from Naphtha , the most fluid , to Petroleum,■which is less fluid, thence to Maltha, which is more*or less cohesive,and thence to Asphaltum , which is solid. Hence the characters of*ome specimens are intermediate between two varieties.
Var. 1. NAPHTHA. ! Kir tv an. This variety is fluid and trans-parent, a little unctuous to the touch, and constantly exhales a verystrong odor. Its colors are grayish or yellowish white, sometimeswith a tinge of green. It swims on water, and its spec. grav. variesfrom 0.71 to 0.84.
It takes fire even on the approach of a lighted taper, and burnswith a bluish flame, yielding a thick smoke, and leaving no residue.
f Var. of Erdol. Werner. Var. of Mineral Oil . Jameson. I,e N aphte.Brochakt. Bitume Is aphte. Brongniart-. Bitume liquide blanchatre.'Haoy.