430 THE COLLIERY GUARDIAN. March 8, 1916. Engineering Company Limited, all of 1, Victoria-street, London, S.W.—Relates to an improved rotary compressor or exhauster of the type comprising two drum-like members arranged.one within the other and eccentrically to one another, and having an annular liquid piston occupying the space between the members, the inner of said members being pro- vided with one or more helical passages through which the air or other gas being operated upon is forced from the inlet to the outlet side of the machine. The invention consists in a compressor or exhauster comprising in combination an outer casing, an inner cylindrical rotary member having one or more helical passages thereon, and a shrouding plate formed or fitted upon one or each side of the inner member; also means for maintaining constant the amount of liquid within the machine. The drawing is a transverse sectional elevation of one convenient form, applicable more particularly as an exhauster. A framework or foundation a for the machine carries b for the bearings c, d, of the outer and inner members respectively (when both are to be rotated), the bearings being disposed symmetrically about the centre line of the machine, or so that the members may be overhung, etc. The outer member e is a hollow casing, and the inner member is cylindrical, and is constructed in two parts q each provided with two threads g (in the one case right-handed, and in the other left-handed), so that the air or gas to be extracted by the machine will be drawn through the hollow shaft m by way of the interior of the inner member, and through the aper- tures p, to be fed along the inner member to the outer sur- faces thereof. The two parts q of the inner member are connected by webs r, and the outer ring-like portions s carry- ing the threads g are bolted, etc., to the members q, and in order to increase the effectiveness of the machine, shrouding plate's t are provided on each side of the ' inner member. (Four claims.) 8886 (1915). Process for the Production of Toluene. W. B. Sifton, and Harding Brothers (Engineers, Westminster) Limited, of 34, Victoria-street, Westminster, London.— Refers to the production of toluene from benzene. The reaction of methyl chloride on benzene in the presence of anhydrous aluminium chloride, and preferably with the addition of iron turnings which prevent free gas, slowly begins at ordinary temperature, and rises to a maximum result at about 50 degs. Cent. Above this temperature the percentage of toluene produced decreases owing to the ten- dency of more than the one CH3 to enter into the chemical combination, thus introducing the higher homologues, and resulting in the production of xylene, or other higher methy- lated compound, according to the increase in temperature. The. reaction of the process is based upon the following formula C6H6 + CH3C1 = C6H5CH3 + HC1. In this pro- cess benzene to be treated is placed in vessels, which are heated to the temperature required by any suitable means. The vessels are mutually connected with pipes to allow the methyl chloride gas to enter the benzene at the bottom of the first vessel, pass through the liquid and also through con- nections to the bottom of the second vessel and one or two (or more) further vessels, as required. When the reaction in the first vessel is finished, it is temporarily disconnected, to be emptied and refilled while the methyl chloride gas is directly introduced into the remaining vessel or the second of the series. The first vessel having been refilled is then replaced, and'becomes the second vessel, or in the case of a series of vessels, the last vessel to receive the methyl chloride, and from which the hydrochloric acid formed by the reaction in the first vessel, and to a small extent in the other vessel, is taken up by a circulating pump, and used for continuous production of methyl chloride by being passed through a vessel containing methyl alcohol and fused zinc chloride. The temperature of this alcohol should be kept well below its boiling point, and provided with a return condenser. The metliyl chloride formed is passed through suitable drying apparatus tn remove all traces of moisture, and is then again taken up by a pump, which will force it again into the vessels containing the benzene to be treated. (Three claims.) 9437 (1915). Improvements in Apparatus for the Pro- duction of Toluene. W. B. Sifton, of 34, Victori a-street, Westminster.—Relates to apparatus for the production of toluene, and, more particularly, for carrying out that process described in Patent 8886/15. The drawing is a side eleva- tion of the complete apparatus. The apparatus comprises a hydrochloric acid generator a, which is heated by a fire grate a1 2 * * * *, and connected by a pipe 1 with a sulphuric acid supply tank b. From the generator a the hydrochloric acid is conveyed by a pipe 2 to a drying tower or towers c, and thence by a pipe 3 to a vessel or vessels d charged with fused zinc chloride and methyl alcohol, the latter being supplied from a suitably disposed supply tank e. The vessels d are heated by steam supplied from a generator 4, etc., and a tubular condenser f communicates with d for the purpose of condensing any alcohol which may pass over during the heating of the zinc chloride and methyl alcohol solution. The methyl chloride from the generator is conveyed to a drying tower or towers g charged with suitable drying material. The benzene to be treated is stored in a tank h1, and thence conveyed by means of a pump 5 to two or more towers h charged with aluminium chloride and iron turnings, the latter being employed as a catalytic agent. The towers are heated by steam, etc., and are provided with baffles to make the gas bubbles pass through continuously while the liquid is in circulation. The methyl chloride gas is passed through the towers successively, and when the benzene in each tower is converted into C6H5CH3 + HC1, the tower is replaced by a freshly charged tower. The liquor from each tower is passed through a filter press i while the hydro- chloric acid is conveyed to a receiver k, and thence to the methyl chloride generator d, to be again utilised for the production of methyl chloride to continue the process. Fresh hydrochloric acid gas is only required to make up wastage which has taken place during the process. The toluene removed from the benzene towers is washed in suitable tanks I provided with stirring apparatus 6, driven by an engine 6a, the washing being effected to remove any hydro- chloric acid which may remain in the toluene. (Two claims.) 23048 (1914). Improvements in Water Tube Boilers. H. L. Vinke, of 31, Laan Copes van Cattenburch, The Hague, Holland.—Relates to water tube boilers having groups of tubes arranged obliquely at both sides of the furnace, which connect the upper drum of the boiler with water chambers placed at each side of the furnace. The invention comprises, outside the main tubes, tubes in close contact which enter the same chambers as the main tubes, and a water chamber at the front of the boiler into which enter tubes also in close contact. Coiled superheater tubes are arranged at both sides, which open into .the collector boxes for the saturated and superheated steam. Fig. 1 is a vertical cross section; and fig. 2 a partial longitudinal section. The steam drum a is connected by means of tubes b, and the generating tubes c, c1 to the two lower drums I. The tubes c are arranged close together to form walls which stop the radiation of heat. A water chamber d, arranged at the front of the boiler, is con- nected by a group of tubes e to the upper steam drum a, or to a part f on the latter, and of tubes m to the lower drums I. These preventing radiation of heat at the front end cf the boiler, which, like the water chambers' d, receives heat from the furnace. The water chamber and the group of tubes e are closed at the back and sides by walls g, g1 made of refractory plates or the like, the walls gl extending longitudinally to the tubes of the boiler. Next to the tubes e could be arranged coiled superheater tubes k, which open into the collector boxes h and i for the saturated and superheated steam. The water chamber d is covered with a heat insulating layer n. (Three claims.) tubes e form a protective iacket for Fie. i gt m Fig.2. e