The first-mentioned preparation of gold--gold-leaf--is the pure metal beaten into very thin leaves, generally 3-1/8 inches, 3¼ inches, or 3-3/8 inches square; but for illuminating purposes it should be still smaller--say 2½ inches square, as it is easier to handle than a larger size. For the same reason it is better to have the leaf double as thick as it is usually beaten. Gold leaf is sold in "books," each of which contains twenty-five gold "leaves," and for ordinary and general purposes, it is by far the best and most useful metallic preparation; but the difficulty of handling and laying it on deters amateurs from employing it, and it is difficult in writing to furnish a practical description of the _modus operandi_. The following is the usual mode:-- "Carefully open the book of gold, and if in so doing you disturb the leaf, gently blow it down flat again. If a whole leaf be required, take a rounded 'tip,' and quietly so place it on the leaf that the top of the tip be close to the edge of the leaf. In so doing, the sides of the tip will be brought down upon the side edges of the leaf, which then can be securely taken up and placed where required. If a small piece of gold leaf only be wanted, cautiously take up a leaf from the book by passing a 'gilder's knife' underneath, and place it on a 'gilders cushion;'[118] lay it flat with the knife, with which then cut the piece of the size required. If when you have laid gold leaf down with the tip it be wrinkly, blow it down flat." The "gilder's tip" spoken of in the above extract is a very thin camel-hair brush, and for unskilled hands a semicircular tip is to be preferred to one of the ordinary form; as with it a leaf of gold may be firmly laid hold of, balanced, adjusted, and placed, without needing any particular knack. For long narrow pieces of gold, the ordinary gilder's tip is probably the best. Gold paper consists of leaves of gold placed upon thin paper, a sheet of which, measuring about 19 inches by 12¾ inches, requires one book of gold. The mat or dead gold is most frequently used in illumination; but, when required, the bright or burnished gold can be procured. Gold paper is usually plain at the back, and when used, is required to be gummed on to the work; but it is far better to have it prepared on the back with a mixture of clear glue, sugar, &c., which can be laid on evenly and thickly, and yet is very strong. Paper thus prepared needs only to have a wet flat camel-hair brush passed over the back; it can then be laid down, and will adhere very firmly. In laying down gold paper, it is well to place a piece of white glazed paper on its face, then firmly to pass over it the edge of a flat rule or burnisher, in order to press down all inequalities and render the surface perfectly smooth.