PURIFICATION.

221

material may only require renewing once a week, or even at longer intervals. The lids mustbe furnished with air-doors, similar to those described for purifiers.

A scrubber was invented by Mr. Lowe, and patented by him in 1S4G, that is divided intotwo compartments, each of which is supplied with a different kind of purifying liquid, andthe gas ascends through both. The two compartments of the apparatus are filled withcoke; the upper one being supplied with a stream of water, or with water slightly acidu-lated, and the lower one with weak ammoniacal liquor. These liquids are conducted fromseparate tanks to two small vertical funnel-shaped pipes mounted on axes, and perforatedon opposite sides, in such manner that the flow of the liquid causes them to rotate, and thusto distribute it equally over the coke. By this arrangement the ammoniacal liquor maybe repeatedly used until it becomes sufficiently impregnated with ammonia to be commer-cially valuable.

An ingenious contrivance by Mr. Golds-worthy Gurney, whereby gas may be broughtinto iutimate contact with water, and thusfreed effectually from residual ammonia, isfigured in the accompanying woodcut. Theapparatus consists of a jet of water under con-siderable pressure, which is directed againsta small disc about a quarter of an inch indiameter. The disc is fixed at the end of amicrometer screw, so that it may be adjustedto the required distance. When the stop-cockto which the jet is attached is turned, theforce with which the water impinges againstthe small disc disperses the fluid into fine

surface to the action of the gas. To producethis effect, the pressure of the water shouldnot be less than 15 lbs. to the square inch.

An apparatus has been contrived by Mr. Trewby for distributing the fluids used inscrubbers, more effectively over the surface of the coke, or other materials introduced intothem. Fig. 76 shows a vertical section of the upper part of the scrubber, and a plan ofthe distributing wheel. The distributing apparatus,—consisting of the siphon pipe A, thehollow arms B B, and the tubes C C,—is supported on the bearer D, and a slow rotarymotion is communicated to it by means of the pulley E. Bolted to the top of the scrubberis a ring F, on which are a number of teeth, that give motion to the small pinions G G, con-nected by spindles with the distributing tubes C C. The fluid when admitted into thesiphon takes the direction indicated by the arrows, and issues in a stream at the ends of thedistributing tubes. These tubes, besides being carried round with the other parts of theapparatus, revolve also on axes of their own, being attached to the pinions which take intothe teeth of the ring F, and by observing a proper proportion between the number of teeth

spray like a mist, and thus exposes the largest

Fig. 75.

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