SODA WATER. This common and refreshing beverage is, as usually pre pared, a supersaturated solution of carbonic acid gas in water. True soda water was formerly prepared (and is still by some manufacturers) for medical use, chiefly as a remedy for heartburn, and certain forms of dyspepsia and calculons complaints ; and consisted of one, two, or three drachms of carbonate of soda, dissolved in a pint of water highly im pregnated with carbonic acid. This is often a valuable remedy ; but would sometimes be attended by mischievous results, especially if indulged in to the extent to a Melt some persons pursue the use of soda water. The mere aqueous solution of carbonic acid, which is made by forcing the gas into water by a con densing pump, and under a pressure of six or eight atmospheres, is an agreeable and, generally speaking, harmless dilu ent.
In a strong vessel, whiting or powder ed marble is placed, and dilute oil of vitriol poured over it: effervescence im mediately occurs owing to the escape of carbonic acid. This gas is conveyed by pipes into the vessel containing, the water to be impregnated, into which it is driven with so much force, and under so great pressure, that a large proportion of the gas is absorbed and retained in solution by the water. When the pressure is re
moved, as when the water is drawn from the fountain, the extra quantity of gas held in solution previously, escapes. Bakewell's apparatus consists of an ex ternal casing of a cylindrical form, with spherical ends, made strong enough to resist a pressure of several atmospheres. There is a partition about two-thirds from the top of the vessel. The bottom part is a receptacle for the chalk, or other suitable material, and water from which the carbonic acid gas is to be generated; then there is a vessel containing diluted sulphuric or muriatic acid, which passes out in small quantities, as required, into the vessel. When the chalk and acid receptacles are to be supplied with those ingredients, the apparatus is to be turned on its pivots to a horizontal position. The apparatus is then to be put into vi bration on pivots, by which the chalk and water will be effectively agitated by the motion of a pendulum, while a small portion of acid y ill escape to keep up the generation o' the gas as it passes off to the water, wnich will, at the same time, by the vibration of the apparatus, be thoroughly mixed with the gas as it escapes into the water.