A freezing mixture for cooling wine, and for freezing ice-creams, may be formed by mixing five parts of sal ammoniac with five parts of nitre and sixteen of water. A mixture of snow or pounded ice and salt produces a most intense cold, but it is only while the salt is melting the ice or snow that the cold is felt. Muriate of lime, mixed with snow, produces a still greater degree of cold. Several other mixtures may be used for freezing; but those producing the most intense cold are mixtures of nearly equal parts of sulphate of soda with nitrous or sulphuric acid, the sulphate predominating. Eight parts of sulphate of soda, mixed with five parts of muriatic acid, will produce a cold equal to zero. When any liquid is to be frozen by these mixtures, the bottle containing the liquid is put into a wooden vessel containing the mixture; and if the cold is to be very intense, the outer vessel may be placed on a flat piece of cork in a much larger empty vessel, the whole being covered with a woollen cloth. Water freezes soonest when it has been boiled, and forms the most compact and beautiful ice.
The principal utensils required for making ice-creams are a tub large enough to contain about a bushel of ice, which must be pounded small, and mixed with salt, nitre, or soda, and a freezing-pot made of pewter, like those sent out with ice-creams. Copper spoons or spaddles are also required for stirring the ingredients of which the ice-creams are composed, while the process of freezing is going on. When all is ready, the ingredients for the ice-creams are poured into the freezing-pot, which is put up to its cover into the tub full of ice and salt, and kept turning round continually by its handle till the freezing is completed. The turning the pot is the most difficult part of the operation, and it requires great attention, as, unless the ingredients are kept in constant motion, the sugar, which is the heaviest, will sink to the bottom, and the other articles will be unequally frozen, so as to form unsightly lumps. The cover must be taken off occasionally, to see how the process is going on, and the cream that has adhered to the sides of the freezing-pot should be scraped off, and mixed with the rest by the spaddle, in order to prevent waste. The whole of the ingredients should also be mixed together with the spaddle if they appear to be settling irregularly.
Ice-creams and water-ices should be perfectly smooth, and soft enough to break easily with a spoon. The ice-creams are made by mashing the fruit with which they are to be flavoured, and adding to a pint of the juice, after it has been strained, a pint of thick cream, the juice of half a lemon, and sugar to the taste. The lemon-juice should be put in last. Sometimes whipped cream is used, the cream being first mixed with sugar, and laid on a fine sieve, turned the bottom upwards in a bowl, as it is whipped, so that the cream which drains from it may not be wasted. Water-ices are generally only the juice of the fruit strained and sweetened, as, if water is added, the ice is apt to freeze too hard. Lemon-ice is composed of the juice of four lemons, and the rind of one, to a pint of clarified sugar-syrup, the whole being strained before putting it into the freezing-pot.
Garden Front of the Manor-House in its improved state.