. The principles of chemistry . 50 PEINCIPLES OF CHEMISTRY Faraday employed the following method for liquefying when passed over dry silver chloride, AgCl, is absorbed by itto a considerable extent, especially at low temperatures.^ The solid the receiver it will cause the temperature in it to fall considerably, and will itself pass intothe aqueous solution. In the end, the same ammoniacal solution as originalh^ taken isre-obtained. Thus, in this case, on heating the vessel the pressure increases by itself,and on cooling it diminishes, so that here heat directly replaces mechani
. The principles of chemistry . 50 PEINCIPLES OF CHEMISTRY Faraday employed the following method for liquefying when passed over dry silver chloride, AgCl, is absorbed by itto a considerable extent, especially at low temperatures.^ The solid the receiver it will cause the temperature in it to fall considerably, and will itself pass intothe aqueous solution. In the end, the same ammoniacal solution as originalh^ taken isre-obtained. Thus, in this case, on heating the vessel the pressure increases by itself,and on cooling it diminishes, so that here heat directly replaces mechanical work. Thisis the principle of the simplest forms of Carres ice-mahing fnachmes, shown in fig. is a vessel made of boiler plates into which the saturated solution of ammonia ispoured; m is a tube conducting the ammonia vapour to the receiver A. All parts ofthe apparatus shouklbe hermetically joined together, and should be able to withstanda pressure reaching ten atmospheres. The apparatus should be freed from air, which. Fig. 44.—Carres apparatus. Described in text. would otherwise hinder the liquefaction of the ammonia. The process is carried on asfollows:—The apparatus is first so inclined that any liquid remaining in A may flowinto C. The vessel C is then placed upon a stove F, and heated until the thermometer tindicates a temperature of 130^ C. During this time the ammonia has been expelled fromC, and has liquefied in A. In order to facilitate the liquefaction, the receiver A shouldbe immersed in a tank of water R {see the left-hand drawing in fig. 44). After abouthalf an hour, when it may be supposed that the ammonia has been expelled, the fire isremoved from under C, and this is now immersed in the tank of water R. The apparatusis represented in this position in the right-hand drawing of fig. 44. The liquefied ammoniathen evaporates, and passes over into the water in C. This causes the temperatureof A to fall considerably. The substance to be refrigerated is p
Size: 1868px × 1337px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1890, bookpublis, booksubjectchemistry
