This section is from the book "Mrs. Allen's Cook Book", by Mrs. Ida C. Bailey Allen. See also: The Conscious Cook: Delicious Meatless Recipes That Will Change the Way You Eat.
All the frozen desserts may be classified under the general term "Ices" and are either water ices or cream ices. Plain water ices consist of sugar syrups, combined with fruit juices, while sherbets are water ices, to which gelatine or whipped egg whites have been added. Cream ices include Philadelphia, custard and junket creams, milk sherbets, frozen chocolate, mousses and parfaits.
The principle underlying successful freezing is that of latent heat, or evaporation, the ice being combined with some material like salt that will cause it to melt, and thereby lower the temperature below the thirty-two degrees of the ice. This causes fluids to become solidfied by. converting their watery particles to ice, and whether or not the mixture is to be smooth, coarse or grainy, or half-frozen, depends on the manner of freezing, the amount of ice and salt to be used, and whether or not they are stirred during the process.
Unless one owns an ice crusher, which costs about five dollars (and worth the price if much ice cream is made) there is no better way to crush ice than by using a wooden mallet and a canvas bag. If a small quantity is to be made, it perhaps is as easy to chip the ice with an ice pick.
The amount of ice and salt necessary for freezing depends upon the desired texture of the dessert being made. All ice creams, water ices and sherbets should be frozen in three parts of ice to one part of salt, by measure. Frappes, which are of coarse texture, should be frozen in equal parts of ice and salt; and mousses and parfaits, which are creams frozen without stirring, should be packed in equal parts of ice and salt. In packing cream, ices, sherbets, etc., after freezing, use four parts of ice to one part of salt, and let stand at least an hour to mould.