211. COMMON SULPHUR, or BRIMSTONE, is a yellow, dry, and brittle substance, which, in burning, yields a suffocating fume: the smell of this, under the denomination of sulphureous, is well known.
Sulphur is found in a pure or native state in nearly all volcanic countries: it is about twice as heavy as water; and is sometimes crystallized in the form of octohedrons, whose bases are rhombs. It exists abundantly in a state of combination with several metallic substances, and is also formed in putrid animal remains.
A great proportion of the sulphur which is used in commerce is obtained by the process of roasting copper, and other ores, previously to their being smelted. It passes off in the form of vapour, and, on being received into chambers constructed for the purpose, is there deposited in a powdery state. The substance thus formed is the flour of sulphur of the shops. It is afterwards melted in large pans, and cast in wooden tubes, to make the hard, or roll brimstone. Nearly all the sulphur used in France comes from the Solfatara of Italy. This volcanic country every where exhibits indications of the agency of subterraneous fires. Nearly the whole ground is bare and white; and, in every part, is warmer than the atmosphere during the greatest heat of summer. A sulphureous vapour is constantly emitted from the earth, and sulphur is condensed in various parts, and in great abundance. This is collected, packed in casks, and exported to Marseilles, where it undergoes certain preparations that are necessary towards purifying and rendering it fit for sale.
A considerable quantity of sulphur is employed in the composition of gunpowder ([206]). Its readiness of taking fire is the reason of its being employed in the making of matches. Sulphur gives a blue colour to artificial fire-works. Its vapour is used for the whitening of silk and wool, and also for the bleaching of straw used for making ladies’ hats.
Modellers employ sulphur to make moulds for various kinds of casts; and artists are enabled, by means of it, to take sharp and beautiful impressions of medals and engraved stones. The mode of doing this is very simple. The sulphur is put into an earthen vessel called a crucible, and placed on a hot fire. It soon melts; and if kept some time over the fire, becomes thick and dark-coloured. When poured into water in this state, it is as soft as wax. It may now be easily worked between the fingers into any given form: and, if pressed upon a seal or engraved stone, will be found to retain a perfect impression of it. It is this property of sulphur of which Mr. Tassie, of Leicester-fields, London, has availed himself, to furnish extremely elegant impressions of many antique gems.
Sulphur was much used by the ancients in medicine; and it is now occasionally administered both as an external and internal remedy. The compounds formed from it are employed to considerable extent in various processes of dyeing and calico printing. Many of the mineral waters, those, for instance, of Harrowgate ([299]) and Moffat ([300]), are indebted to sulphur for their most valuable qualities.
This substance has the property of becoming electric by rubbing. On exposure to a gentle heat, it melts; but if the heat be increased, it is entirely consumed, and passes off in vapour. When ignited, and the combustion is slow, it burns with a suffocating and acid fume, and blue flame; but when the combustion is quick it burns with a white and vivid flame. If exposed to a sudden, though gentle heat, by holding it, for instance, in a hand when that is warm, it will sometimes break in pieces with a crackling noise.
It is a remarkable circumstance, that, if a bar of iron be heated to perfect whiteness, and then touched with a roll of sulphur, the two bodies combine, and drop down together, in a fluid state, forming what is called sulphuret of iron, a compound of the same nature as iron pyrites ([236]). A piece of iron rolled out very thin may be apparently melted in the hand, by putting it, when heated to whiteness, upon a thick piece of solid sulphur. It is, however, necessary, that this experiment be performed with great care; and under a chimney, or in a place where there is a current of air, to carry off the suffocating vapour.
Useful as sulphur is, in various ways, its most important application is supposed to be for the production of sulphuric acid, or spirit of vitriol ([24]). One mode in which this acid is obtained for the purposes of commerce, is by burning a mixture of sulphur and nitre ([206]) in large chambers lined with lead. In this process the nitre supplies a considerable portion of oxygen ([21]) to the sulphur, and the air of the atmosphere furnishes the rest. Thus a substance which, in a natural state, is one of the mildest that we are acquainted with, is by this operation converted into a corrosive and dangerous, though useful fluid. Its taste is strongly acid: and, when applied to animal or vegetable substances, it soon corrodes, and destroys their texture.
The properties of sulphuric acid have rendered it extremely valuable for numerous purposes, both in the arts and in the laboratory. It has been long employed by chemists, as one of their most useful and frequent agents.