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.