926

SULPHUR.— Suli-hides.

high a temperature as to fuse sulphur, therefore itcan no longer become solid in contact with them,but condenses on their surface in a liquid form, andruns to the bottom, where it collects. When theoperator is satisfied that sufficient has distilled oyer,he proceeds to remove it; this he does by means ofthe plug apparatus, figured at F, which is simply aniron plug with a tolerably long shank or handle, asis shown in the drawing. By pushing this pluginwards he opens the passage for the flow of theliquid sulphur, which runs into suitable moulds, toform the stick or roll sulphur of commerce. Theresidue is raked out of the retort, which is imme-diately charged again by removing the plug whichcloses the tube or passage between the vessel, b,and the retort.

A better apparatus is figured in Payen’s Precisde Chimie , in which two retorts are attached toone condensing chamber; these retorts are cylin-drical, and resemble to a certain extent ordinarygas retorts. A portion of the door which closes theouter end of the retort is movable, to enable theoperator to rake out the debris after distillation;the other end of the retort rises like a swan’s neckbefore opening into the condensing chamber. Overthese openings or orifices within the chamber hangsa damper or register in such a manner that it can,from the outside, be placed over them, thus cuttingoff all communication between the retort and thechamber. A fusing vessel heated by the waste heatis attached, as in the drawing just given. Thisdescription of apparatus has the advantage that byits means the operations can be rendered continuous.For instance, let one retort be called A, the other b;suppose retort A charged at a certain hour, andretort B charged some two hours later, it is certainthat, if .charged with an equal weight of rawmaterial, the retort A would be ready for rechargingtwo hours before retort B. Supposing this to bethe case, the damper or sliding plate is allowed tofall over the opening of retort B, thus closing thepassage between it and the condenser, and preventingthe rushing back of any sulphur vapour. The coveris removed from the front opening, the impureresidue raked out, after which it is again closed,the entrance into the condensing chamber is againopened, a charge of sulphur is run in from thefusing vessel, and the distillation again commences.During the whole of these operations retort b hasbeen uninterruptedly at work; but eventually thesame operations have to be performed in connection■vyith it as have been detailed with respect to retort A.Thus between the two a constant stream of sulphurvapour is being perpetually driven into the con-densing chamber ; the work going on almost withoutinterruption, as the retorts never want chargingsimultaneously.

Sulphur thus produced is almost pure. It istrue that the sublimed sulphur in powder—thatis, the flowers of sulphur—contains a small quantityof sulphur dioxide, which, when the sulphur hasto be applied to certain purposes, must be removedby washing with water. This, however, is the only |

body with which it is contaminated; the roll sulphuris free from sulphur dioxide.

Combinations of Sulphur. — Sulphur enters intomany combinations, both simple and complex; itcombines with hydrogen, and, with a few exceptions,with all the metals, with oxygen in several propor-tions, with carbon, phosphorus, chlorine, iodine, andbromine.

Sulphides .—Sulphide of hydrogen, sulphydric acid,or sulphuretted hydrogen, II 2 S, is the transparentcolourless gas, well-known for its nauseous odour,which is most offensive when in very small quantity.It exists in many mineral springs, such as Harrogateand others. It is a product of the decompositionof many organic bodies, and is evolved by putridbodies, and is the cause of the smell of rotten eggs,the albumen of which, in undergoing decay,gives off its sulphur, or a part of it, as sulphideof hydrogen.

The density of sulphuretted hydrogen is 17,hydrogen being 1. It may be liquefied by pres-sure of 17 atmospheres, at SO 0 Fahr. (10° C.), andeven solidified by a powerful refrigeration. It isa most poisonous gas; air containing one-tenth of aper cent, of this gas causes the death of some smallanimals. It acts as a powerful narcotic. It burnswith a blue flame.

The gas is soluble in water, which, when cold,takes up about its own volume ; this solution formsa useful laboratory reagent.

Sulphuretted hydrogen may be prepared by add-ing an acid to any soluble sulphide, such as thoseof the alkalies or the alkaline earths, or to aninsoluble sulphide, such as sulphide of iron or sul-phide of antimony. The most general method consistsin adding dilute sulphuric acid to sulphide of iron.

The decomposition which produces this gas is verysimple—

FeS + II 2 S0 4 = FeS0 4 + U 2 S.

Finely powdered antimony trisulphide yields sul-phuretted hydrogen when acted on by boilinghydrochloric acid. The reaction is thus—

Sb 2 S 3 + 6IICI := 2SbCl 3 + 3H 2 S.

Persulphide of hydrogen (II 2 S 2 or II 2 S 8 ) is pro-duced in the form of oily drops, when a solution ofpotassium pentasulphide is poured into dilute hydro-chloric acid. It is very unstable; the greatest careand precaution cannot preserve it more than a fewweeks, even though it be sealed hermetically in aglass tube. It simply forms a link in the chain ofcombinations that sulphur is capable of forming.

Metallic Sulphides .—In speaking of the naturalcompounds of sulphur many of these have beennamed, and attention need here only be called tothe fact, that the artificial formation of the metallicsulphides is of constant occurrence in analysis. Bythe property of forming soluble or insoluble sul-phides chemists are able to separate the metals into,three classes. The following metals are throwndown as sulphides by sulphuretted hydrogen from anacid solution—gold, platinum, mercury, silver, lead,

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