=Richardson’s Ether Spray-Producer= (fig. 121) consists of a tube on which two india-rubber bags are placed; one, protected by a silk net, acts as a reservoir; the other, furnished with a valve, is the pump; these drive a constant stream of air over the tip of a fine tube projecting from a flask of ether; this sucks up the ether and throws it in fine spray on the surface to be chilled by its evaporation. The ether for this purpose must be very pure and dry, having a specific gravity of ·720, or the evaporation will not be sufficiently rapid to produce congelation. The first effect of the spray is a numbing aching pain with reddening of the surface. This is succeeded by a pricking pain. In ten seconds, if the ether be good, a dead white hue spreads rapidly over the skin, and when this appears the surface is quite insensible. The bottle and elastic air-pump may be attached to the glass jet seen in the corner of fig. 121, which then makes an apparatus for injecting astringent solutions in spray over the nasal passages, the throat, and air-tubes; but the tubes used for watery fluids are much wider than that for pulverising ether into spray. Tannin in solution of 3-10 grains to the ounce of water, sulphate of zinc, or alum in similar quantity, may be thus inhaled with much benefit by persons suffering from chronic congestion of the mucous membranes. =Injecting Chloroform Vapour into the Uterus= is a ready means of relieving pain in cancer of that organ; special apparatus is made for the purpose, but an ordinary elastic clyster syringe will answer the purpose, if the flask is unscrewed and a few drops of chloroform are poured into it, from time to time, while air is pumped through the delivery tube, which is passed up the vagina to the ulcerated cervix-uteri. =Subcutaneous Injection.=—The syringe for this operation (fig. 122) consists of a graduated glass tube holding six minims. The piston works in a silver continuation of the graduated tube, and is thus kept clear of the solutions used for injection. To the nozzle of the syringe fine sharp-pointed cannulæ are screwed on; they are of different lengths, some of steel, others of steel gilt; the gilding renders the points very blunt, and consequently much more painful to insert. In filling the syringe, care should be taken not to draw the fluid above the level of the graduation on the tube, that the exact amount injected may be read off as the liquid sinks in the tube. The finer the cannula, and the sharper its point, the less pain is caused by its introduction. [Illustration: Fig. 122.—Subcutaneous Injection.]