Harrison's ice-making machine and its im- proved form by Mr. Siebe is a particular ap- plication of the exhausting air-pump. The working of the process is as follows : — ^A quan- tity of sulphuric ether contained in a close vessel surrounded by a current of salt water, is made to pass rapidly into a state of vapour by the action of a large air-pump driven by steam- power, the necessary amount of heat requisite to effect this change in the ether is abstracted from the suiTOunding salt-water casing, which is thus cooled to a temperature below the freezing point of water, and is then made to cii'culate through a box containing the water to be frozen in tin moulds arranged on a tra^ veiling frame, which moves in a direction con- trary to the refrigerating current. The ether- vapour removed at every stroke of the pump is- passed over to a condenser, where it reassumea the 'liquid form and is returned to the evapora- ting vessel. The machine invented by M. Carre appears to be much more effective. Messrs. Carre and Co.'s ice-making machines are of two kinds, one being continuous and the other intermittent in action ; but the principle involved is the same in both cases, viz., the i:)roduction of cold by the volatilisation of a gas which is easily liquefiable, and at the same time ia a high degree soluble in water. — TJre. Dr. Meidinger, of Baden, has constructed a little apparatus for freezing cream or cooling wine, and which has been very favourably re- ceived, as being simple, elegant, and automatic. The freezing mixture consists of finely-pounded ice and a saturated solution of table salt. Since, however, the melting ice necessarily dilutes this solution, a reservoir containing dry salt is introduced in such a manner as to constantly supply the deficiency of salt and keep the solu- tion unaltered upon the point of saturation. For this purpose Dr. iVIeidinger advises the following arrangement : — In an external cylin- drical vessel, a bad conductor of heat and very much like a water-cooler, an annular perforated. vessel is suspended to contain the dry salt above- mentioned. A slightly conical metallic cup re- ceives the material to be acted upon, and fits. into the circular opening left for the purpose. The mush of pounded ice and brine is poured into the outer vessel, up to a certain mark, just enough to make it rise to the very rim as soon as the cup containing the cream, &:c., is slowly REP ( 725 ) HEG down. This rising ice mixture enters the reservoir of dry salt, and as long as ice is melting salt will be dissolved and the cooling action will thus be kept up uninterrupted. No tui-ning is required; the freezing compound, however, should be stirred occasionally, as the portion ia immediate contact with the freezing mixtirre will congeal iirst. The temperature attained is about 6" — 7° below zero, Fahr.

AI-modernized reading of the original text

Harrison's ice-making machine and its improved form by Mr. Siebe is a particular application of the exhausting air-pump. The working of the process is as follows : — ^A quantity of sulphuric ether contained in a close vessel surrounded by a current of salt water, is made to pass rapidly into a state of vapour by the action of a large air-pump driven by steampower, the necessary amount of heat requisite to effect this change in the ether is abstracted from the surrounding salt-water casing, which is thus cooled to a temperature below the freezing point of water, and is then made to cii'culate through a box containing the water to be frozen in tin moulds arranged on a travelling frame, which moves in a direction contrary to the refrigerating current. The ether-vapour removed at every stroke of the pump is passed over to a condenser, where it reassumes the liquid form and is returned to the evaporating vessel. The machine invented by M. Carre appears to be much more effective. Messrs. Carre and Co.'s ice-making machines are of two kinds, one being continuous and the other intermittent in action ; but the principle involved is the same in both cases, viz., the production of cold by the volatilisation of a gas which is easily liquefiable, and at the same time ia a high degree soluble in water. — Ure. Dr. Meidinger, of Baden, has constructed a little apparatus for freezing cream or cooling wine, and which has been very favourably received, as being simple, elegant, and automatic. The freezing mixture consists of finely-pounded ice and a saturated solution of table salt. Since, however, the melting ice necessarily dilutes this solution, a reservoir containing dry salt is introduced in such a manner as to constantly supply the deficiency of salt and keep the solution unaltered upon the point of saturation. For this purpose Dr. Meidinger advises the following arrangement : — In an external cylindrical vessel, a bad conductor of heat and very much like a water-cooler, an annular perforated. vessel is suspended to contain the dry salt abovementioned. A slightly conical metallic cup receives the material to be acted upon, and fits into the circular opening left for the purpose. The mush of pounded ice and brine is poured into the outer vessel, up to a certain mark, just enough to make it rise to the very rim as soon as the cup containing the cream, &c., is slowly REP ( 725 ) HEG down. This rising ice mixture enters the reservoir of dry salt, and as long as ice is melting salt will be dissolved and the cooling action will thus be kept up uninterrupted. No turning is required; the freezing compound, however, should be stirred occasionally, as the portion in immediate contact with the freezing mixture will congeal first. The temperature attained is about 6" — 7° below zero, Fahr.

Cassell's dictionary of cookery