This section is from the book "Practical Cooking And Serving", by Janet McKenzie Hill. Also available from Amazon: Practical Cooking and Serving: A Complete Manual of How to Select, Prepare, and Serve Food [1919].

Cakes are decorated with sugar in various forms, with fruit or with nuts, either alone or combined with sugar, also with butter combined with sugar. The simplest decoration is obtained by dusting a baked cake with white or tinted, powdered or granulated, sugar; this decoration is especially appropriate when the cake is baked in layers, and these are held together with whipped cream or a custard filling. The sugar will adhere to the cake much better if the cake be first brushed over with white of egg or fruit jelly. Sugar of one color may be used, or the cake may be scored in some pattern as diamonds, squares, etc., and the design may be filled in with sugar in two or more colors. The decoration next in order, as regards simplicity of production, is obtained by sprinkling the top of the cake with either powdered or granulated sugar before baking; this may be elaborated by inserting blanched and halved almonds sidewise in the top of the cake, and sprinkling the whole with sugar. Fruit may be used in the same manner.
When sugar, used for decoration, is mixed with liquid, to form a mixture, and this is spread upon a cake so as to cover completely its surface, the cake is said to be frosted or iced.
The process of forcing frosting or icing through a bag with tube attached, so as to trace a design upon the cake, is called piping. Only specially prepared icings can be used for piping.
A frosted cake is decorated with piping alone; or coarse, colored sugars, citron, glacé fruits, nuts, small candies and fruit jellies are combined with the piping.
With the exception of the syrup for chocolate icing, which is of granulated sugar, and which might be classed among the cooked icings, all uncooked icings are made of confectioner's sugar. This sugar is considered finer than ordinary powdered sugar. When eggs are called for, they should be fresh; nuts should be without rancidity, and all flavoring materials the choicest in quality.
The utensils needed in decorating are few: a sieve with a very fine mesh, twenty-eight holes to the linear inch, through which the dry sugar should always be passed, is of the utmost importance. For ornamental icing a round bottomed bowl, a wooden spatula, or perforated spoon, for mixing, and bags with tubes for piping the mixture, are also essentials.
The bags for holding icing that is to be piped may be bought, or, at very slight expense, made at home. (See Pastry Bag and Tubes.) Copper tubes may be bought, in sets of six or twelve, at a confectioner's or a large kitchen furnishing store. These afford shapes for large and small rounds, stars, leaves, ribbons, cords, and frills. The angle at which the bag is to be held while at work depends upon the position of the surface to be decorated and the style of decoration; this is readily determined upon trial.
 
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