Before the fibrous substance is removed from the vessel b, an atmosphere of steam is driven through the mass from the perforated coil c. The bisulphide is volatilized by this means, and the' vapour is conducted up the pipe p to the condensing vessel g, where it is reduced to a liquid state, and may then be run back again into tho tank a. A small closed tank r is provided betweeu the extractor b and the pump n, into which the bisulphide may be allowed to flow through the tap n7, in case of accident to the extractor or pump. A draw-off tap n* is provided at the bottom of the vertical pipe n2, to empty it previous to taking the pump to pieces for inspection or repair. It will be seen that the pipe p communicates with the worm g' of the condenser, and that both it and the pipe d' are provided with a tap, for dosing communication with the worm when required. The bisulphide may thus be used over and over again, and a large quantity of material be thoroughly cleansed from grease with very little waste of bisulphide, as none of the vessels are opened while there are any signs of the bisulphide being present. A running-off tap q is adapted to the bottom of the vessel b, for the purpose of letting out water or other liquid, used from time to time for cleansing the vessel. The tank a is provided with an overflow pipe, for withdrawing any excess of water resulting from the condensation of the steam used iu vaporizing the bisulphide, and for blowing off the air which enters the apparatus during the operation of charging.
Iu the extraction of bitumen from schist% about 5 per cent. more product is obtained by treating with bisulphide of carbon than by the destructive distillation process, which, besides being very expensive, only yields about 8 per cent. altogether. For this purpose, the bisulphide is largely used in Galicia. In the same country, it is employed for extracting sulphur from a gypseous earth containing about 141 per cent. of that mindral, with a loss of only about 1 .66 per cent. of bisulphide. It is essential that the sulphur earth to be treated shall be perfectly dry, or the bisulphide cannot perform its duty.
The very low boiling point of bisulphide of carbon has caused engineers to turn their attention towards using it as a ruotive power. The Ellis bisulphide auxiliary for reducing the consumption of fuel for steam engines, is already well known in America at least. It can be fitted to all systems of steam engines, whether expanding or no, and requires no essential alteration in the construetion ; but lubrication must be effected with water, as grease would be dissolved. Our American cousins have gone yet another step in advance. Glycerine has no affinity for bisulphide of carbon, and is capable of mechanical evaporation in the presence of its vapour ; it is a much bettor conductor of heat than water, and is capable of being heated to a certain degree with a less proportion of fuel, also of storing up caloric. When heated in a metal vessel, it becomes thin, and spreads over tho surface, forming a protection and lubricator. The hisulphide is easily evaporated to a dense vapour, the latent heat absorbed for vaporization being about 280° F., that of steam about 1000° F., or a
saving of 71 per cent. in the fuel. To utilize these substances in the creation of motive power, the apparatus shown in Fig. 474 has been constructed : A is a boiler ; B, a condenser ; C, a furce pump ; D, a feeder ; and E, the cylinder of an ordinary engine. To produce power, the boiler A is tilled with glycerine, and boated to a temperature uf 43°-260° (110°-500° F.) ; the valve b is opened, and a small quantity of bisulphide is run from D, through a perforated pipe a, into the boiler, and is thus brought into contact with the heated glycerine G, pro ducing a pressure of vapour corre sponding with the amount of bi sulphide allowed to enter. The engine is now started by openiug the inlet valve on the supply pipe c, and the vapour, after impart ing its force in the cylinder, is dischozged into the exhaust pipe d, which proceeds direct to the condenser B, when it passes through a series of worms, cooled by water flowing iuto the cistern e by the vdve f, and out by the overflow g, and is thus condensed again into a liquid form, run down into the receiver h, and stored for future use. To regulate t,he flow of bisulphide so as to obtain a uniform quantity, the receiver h is connected by a double pipe ij with the force-pump C, and by the pipe k with the feeder D, so that the latter vessel, wbich holds a quantity of the material, is supplied as required, and regulates a steady flow by the valve b, independent of the action of the pump. To ascertain the contents of the feeder and receiver, two glass gauges are fixed at 1, m. At n is a gauge for indicating the amount of vacuum produced by the condenser, and therefore useful to determine the necessary quantity of water by the inflowing valve f. The feeder D has a valve p and a pipe o at its upper part, direct to the top of the evaporator or boiler, so as to equalize the pressure and flow of the liquid bisulphide by the valve b, as before explained. To ensure against any loss of material through accidental excess of pressure, s. safety valve is connected by a branch pipe s to the exhaust pipe d, the excess being then saved by passing direct to the condenser. The presence of air would partially prevent the condensation of the bisulphide, and cause a back pressure instead of a vacuum; therefore, before fuming in the bisulphide by the funnel v, or on starting for the first time, the air is exhausted as far as possible, by working the pump C by hand, closing the circuit by valves b, p, and opening t. .During evaporation, the small portion of glycerine forced from the bulk proceeds with the vapour through all the pipes, ex., to the cylinder by which the power is utilized, and their gravity being nearly the same, the liquid bisulphide does not sink down or come in contact with the metal of the boiler, but is discharged as vapour from the surface of the bath of glycerine. This vapour may be utilized by any kind of engine, and may be led by the exhaust pipe direct to the condenser, for the purpose of extracting the latent and sensible heat, reconverting it for re-use.