Sulphur is a bad conductor of heat, and the mere heat of a warm hand often causes it to crackle, and even to fall to pieces, from the unequal expansion. It is an insulator of electricity, and becomes negatively electric by friction. It is slightly soluble in alcohol, ether, and the fatty oils; its best solvents being the bisulphide of carbon and chloride of sulphur. When it is heated in the air, it takes fire at about 470°, burning with a blue flame, and becoming converted into sulphurous acid, whose pungent suffo cating fumes are characteristic of sulphur. This element is second only to oxygen in its powerful affinity for other elements, with most of which it unites, and often in several proportions. With most of the metals it combines very readily, and in some cases, with a development of light and heat; thus, silver and copper burn in sulphur-vapor just as iron-wire or zinc-foil burns in oxygen. In consequence of its power, with the aid of heat, of forming sulphurous acid with the oxygen of the air, and thus rendering the latter incapable of supporting combustion, burning sulphur may be usefully employed for the extinguishing of fire—as, for example, in chimneys.
Sulphur occurs very widely distributed in the mineral kingdom, partly free and partly combined with other elements. The free sulphur is either found pure in regularly formed crystals, or intimately mixed with earthy matters. The principal sources of crystalline sulphur are Urbino in Italy, Girgenti in Sicily, and Radoboy in Croatia; while the earthy sulphur is mainly derived from Italy, Moravia, and Poland. Iceland is rich in both varieties, but the mineral wealth of that island remains almost unworked. At present, by far the greatest quantity of the sulphur employed in Europe comes from Sicily; and, as a general rule, it is abundant in volcanic districts. In the form of sul phide, sulphur occurs abundantly in combination with iron, copper (iron and copper pyrites), lead (galena), zinc (blende), etc., the bisulphide of iron (or iron pyrites) furnish ing most of the sulphur that is employed in the manufacture of sulphuric acid. Sulphur is still more extensively distributed in the form of sulphates, the sulphates of lime, magnesia, baryta, etc., being abundant natural productions. In the vegetable kingdom, sulphur is a constituent (although only to a small amount) of the albuminous bodies which are so widely diffused in plants; and of certain volatile irritant oils, as those of mustard, garlic, asafetida, etc.; and, moreover, the vegetable juices contain it in the form of certain sulphates. In the animal kingdom, it is not only a constituent of the albuminous, fibrinous, and gelatinous tissues, but of the hair, saliva, bile, urine, etc. The two animal substances in which it is most abundant are cystin (q.v.), an occasional constituent of urinary calculi, and taurine (q.v.), a constituent of the bile, in bothRof which it forms about a quarter of the entire weight.
It would be out of place in this article to enter into details regarding the extraction or preparation of sulphur. It is sufficient to state that the grosser impurities are removed
by crude processes of fusion and distillation at or near the place from whence it is obtained. That which is imported into Britain undergoes further purification. What is called refined sulphur is that purified by distillation in a large cast-iron still, and con densed in a receiver kept cool. When the vaporized sulphur is condensed in a large chamber, it is obtained in the form of sublimed sulphur, or flowers of sulphur; but as the walls get hot, it melts and collects on the floor, and is run into cylindrical wooden molds, from which, when cool, it is taken out as roll or stick sulphur. The residue left in the retort is a mixture of sulphur with various impurities. Under the names of black sulphur, or sulphur vivant (commonly inquired for at the chemist's under the title of sulphur of ivy), it is used in veterinary medicine, and for the purpose of dressing moldy hops. Sulphur is thrown down from certain of its compounds (as from a strong solution. of a polysulphide of calcium, sodium, or potassium) by dilute hydrochloric acid; it falls as a grayish-white, very fine, light powder, known in the Materia Medico, as milk of sul phur, or precipitated sulphur. For the method of obtaining sulphur from iron pyrites, we must refer the reader to Miller's Inorganic Chemistry, 2d ed. p.154. The proceeding is usually conducted on a large scale, 2,000 tons of pyrites being roasted at once, the roasting extended or five or six months, and the final result being about 20 tons of sulphur. The most common impurities met with in ordinary commercial sulphur are selenium and realgar (bisulphide of arsenic). Flowers of sulphur frequently exhibit a slight acid reaction, in consequence of a little sulphurous acid clinging to them. By rinsing them with water, this impurity is at once removed.
Sulphur is extensively employed in the arts and manufactures; as in the manufacture of matches, gunpowder, etc. When converted into sulphurous acid, it is employed as a powerful bleaching agent, and also for the destruction of insects, fungi, etc.; but its chief consumption is in the manufacture of sulphuric acid.
The compounds of sulphur and oxygen are no less than seven in number, all of which present the characters of acids. These acids have the following composition: Sulphur. Oxygen.
Sulphurous acid .......... SO, 16 16 Sulphuric acid SO, 16 : 24 Hyposulphurous acid 32 : 16 Hyposulphuric acid ........ S,O, 32 : 40 Trithionic acid S,06 48 : 40 Tetrathionic acid 64 : 40 Pentathionic acid S,O, 80 : 40 The last five of these acids have never been obtained in the anhydrous form. We shall only notice the most important members of this group, viz., the first three of them, and of these, the second, sulphuric acid, is so extremely important, that it is discussed in a special article. (The last three derive the essential portion of their name from the Greek word theion, sulphur.