Stamps are, however, very often surreptitiously removed by means of moisture. The following recipe renders this difficult. It consists of two preparations, one of which is applied to the stamp and one to the letter. It is particularly needed in America, where, according to a statement in a newspaper, nearly one-third of all the postage-stamps are removed from letters, cleaned, and used over again.
I. For the Letter.
| Chromic acid | 2.5 | gr. |
| Caustic potash | 15.0 | ” |
| Water | 15.0 | ” |
| Sulphuric acid | 0.5 | ” |
| Sulphuric copper-oxide of ammonia | 30.0 | ” |
| Fine paper | 4.0 | ” |
II. On the Stamp.
| Sturgeon’s bladder in water | 7.0 | gr. |
| Vinegar | 1.0 | ” |
The chromic acid forms with the glue a substance insoluble in water, which causes the stamp not to yield to moisture. The two should be kept in two cups, and the letter first smeared with one and the stamp with the other. I have read of a physician who, finding that his postage-stamps were often stolen, adopted the precaution of giving their backs an application of croton-oil, or some similar powerful “anti-thief-matic,” the result of which was great temporary illness in his landlady and her family. For this recipe the reader must apply to a chemist!
Eder’s Gum for Photographs.—Dissolve oxyhydrate of ammonia in vinous acid, to one part of which add twenty of starch-paste.
Cement for Leather or Paper in Binding Books, &c.—Take 1 kilogramme of wheat-flour, and make it to a paste with 20 grammes of finely powdered alum. Boil this till a spoon will stand uptight in it. Cover the cardboard or cover with this, lay the leather or muslin upon it, and then with a roller press one upon the other. Leather should first be damped. Care must be taken that the paste be not too moist; secondly, that it is laid on very evenly and thinly.
Engravings or texts which have had a piece torn out can be restored as follows:—
Obtain a photograph from a perfect copy on corresponding paper, then with gum set it in, so as to supply the deficiency.