Another modern and very useful application of gas as a heating medium is the “Geyser” or rapid water heater for the supply of hot or boiling water to baths, lavatories, &c., or for business purposes where it is not convenient or desirable to fit up a circulating boiler (see hot-water apparatus). These heaters can be obtained from any ironmonger’s or gasfitter’s. The principle is somewhat different in the various makes, but it all results in the same thing, which is to bring a small volume of water in contact with a large heating surface. The apparatus is generally cylindrical in form. A cock is at one side for attaching the cold supply, and the heated water flows out from a spout at the other side; there is also a cock for attaching the gas supply; they are made in various sizes to supply and fill a bath three parts full of water at 100° F. in 5, 10 or 15 minutes, or to boil water at the rate of ½, 1 or 2 gal. per minute. These are extremely useful appliances where gas is available, being ready for use at a moment’s notice, and the water can be had at any temperature at will; with a modern and properly constructed “Geyser” the water is quite suitable for drinking purposes. The Marsh-Greenall Gas Heating Stove, Fig. 46 (makers, Greenall and Company, 120 Portland Street, Manchester), is both regenerative and radiating, the heat developed and utilised per foot of gas by this system being far greater than by the ordinary atmospheric stoves. Ordinary luminous flames are used, these being fed by superheated air. There is no smell and no danger “of lighting back.” The great heat obtained by this system is radiated from a polished reflector. The consumption of gas is only 12 ft. per hour. See Gas Heating also, p. 994. [Illustration: 46. Marsh-Greenall Gas Stove. 47. Eureka Oil Stove.] _Oil Stoves._--Warming stoves which burn oil fuel are to be commended for many purposes, but are not generally considered suitable for living rooms--bedrooms, for instance--unless the air is continually changed by open doors, &c., as there is a noticeable odour from the burning oil. Rippengille’s are considered the best, and are obtainable at almost any oil, lamp, or ironmonger’s store, or at the chief retail agents, the Holborn Lamp Co., 118 Holborn, London. Fig. 47 is their “Eureka” cheerful reflector stove, suitable for office or shop use. These stoves are adapted for warming conservatories where a high temperature is not required, as a very small stove will suffice to keep the frost out; they are also suitable for servants’ bedrooms and attics where no fireplaces exist. They are made with metal (unbreakable) oil containers, which slide out for lighting, trimming, &c., and they burn the ordinary petroleum oil; it naturally follows that the better and more refined oils give the best results with these stoves, with less liability of smell.