SULPHUR (symb. S, eq. system, 32--sp. gr. of rolled sulphur, 1.98 [see ATOMIC WErourrsj, and of amorphous sulphur, 1.957; sp. gr. of vapor, 6.617 at 824°, and 2.2 at 1900°, atmospheric air being the unit of comparison for the vapor) is one of the most important of the non-metallic elements. At an ordinary temperature, it exists as a solid, brittle, tasteless, and inodorous body, of a characteristic yellow color, and insoluble in water. A piece of solid sulphur, heated to a temperature of 239°, fuses into a thin yellow liquid; while in closed vessels, it may, by a further heat, be distilled, the boiling-point being about 824°, and at this temperature it yields a deep yellow vapor, of sp. gr. 6.617. When the sulphur-vapor comes in contact with cold air, it condenses in the form of a fine yellow powder, known as flowers of sulphur. If fused sulphur be rapidly cooled, it solidifies into a compact mass, of a granular crystalline texture, and if, in its liquid state, it be allowed to run into cylindrical wooden molds, we obtain it in the ordinary form of roll-sulphur, or common brimstone; if, on the other hand, it be allowed to cool slowly, it crystallizes in long, glistening, deep, yellow, oblique prisms, with a rhombic base, which, however, soon lose their most characteristic properties. As native sulphur is met with in yellow crystals, whose form is derived from the octahedron with a rhombic base, it is obviously a dimorphous substance. It has been already stated that sulphur fuses at 239°; from that temperature up to 280°, it forms a yellow, transparent, limpid liquid; as the heat increases, the color becomes brown, and almost black, and the liquid becomes viscid, these changes being very distinctly seen at 350°. If the external application of heat be steadily continued, it will be found that for a while the temperature remains constant, but it afterward rises, and at nearly 500°, the sulphur again liquefies, although less completely than when first melted. If it be now suddenly cooled by pouring it, in a slender stream, into cold water, we obtain a spongy, tenacious, and plastic mass, which may be drawn out into elastic threads, whose color, after they have cooled, varies from an amber to a deep brown color, according to the heat that has been employed. After some hours the ductile sulphur loses its character
istic properties, increases in density, and returns to the brittle form; or, if it be heated to 212°, it suddenly returns to the brittle condition; the temperature rising to 230° dur ing the change. Hence, sulphur may be obtained in three (if not in more) allotropic states, which are distinguished by the symbols Sa, S13, Sy. The first variety, Sa, is the native octahedral crystal of sulphur; it may be obtained artificially by dissolving sulphur in bisulphide of carbon, or chloride of sulphur, and submitting the solution to sponta neous evaporation. These crystals are semi-transparent, of an amber-yellow color, and undergo no change on exposure to the air. The second variety, S/3, is the oblique pris matic crystal already described as being formed when fused sulphur cools slowly. The best method of obtaining these crystals is to melt a few pounds of sulphur, and allow it to solidify on the surface. On perforating the external crust with a hot wire, and pouring out the sulphur that remains liquid, the interior of.the cavity is found to be traversed hi all directions by these crystals, occurring as transparent brownish needles, having a specific gravity considerably less even than that of roll-sulphur. On exposure to the air they soon lose their coherence, and form an opaque and crumbling mass, con sisting of minute rhombic octahedra. This conversion of the prismatic into the octa hedral form takes place immediately if the prisms are immersed in bisulphide of carbon. The third variety, Sy, is the plastic amorphous sulphur, which has been sufficiently described. If sulphur be frequently heated to 600', and suddenly cooled, a black vari ety of this element is produced; and a red variety has been obtained, but the redness is now supposed to be due to the presence of a trace of some fatty body.