ll keep out
insects. A little glue dissolved in the vinegar will make it stronger. It
leaves the pasted scrap-page flexible, adheres firmly, dries quickly, and
does not give a varnishy look to even the thinnest print paper.

A PASTE WHICH WILL NOT SPOIL.

A paste that will not spoil is made by dissolving a piece of alum the size
of a walnut in one pint of water. Add to this two tablespoonfuls flour
made smooth with a little cold water, and a few drops of oil of cloves,
putting the whole to a boil. Put up in a glass canning-jar.

ELECTRIC PAPER.

Electric paper may be made thus:--Tissue paper or filtering paper is
soaked in a mixture consisting of equal quantities of saltpetre and
sulphuric acid. It is afterwards exposed to dry, when a pyroxyline (a
substance resembling gun-cotton) forms. This is in the highest degree
electrical.

A SILVER SOLDER.

To make silver solder melt together 34 parts, by weight, silver coin, and
five parts copper; after cooling a little, drop into the mixture 4 parts
zinc, then heat again.

AN ALLOY FOR GLASS OR METAL.

The following alloy, it is said, will attach itself firmly to glass,
porcelain or metal.--Twenty to thirty parts of finely pulverulent copper,
prepared by precipitation or reduction with the battery, are made into a
paste with oil of vitriol. To this seventy parts of mercury are added, and
well triturated. The acid is then washed out with boiling water and the
compound allowed to cool. In ten or twelve hours it becomes sufficiently
hard to receive a brilliant polish, and to scratch the surface of tin or
gold. When heated it is plastic, but does not contract on cooling.

AN IMPROVED PROCESS OF PHOTO-ENGRAVING.

The metal plate, of copper or zinc, is coated with a very thin layer of
bitumen of Judaea, and when this coat has become perfectly dry, a film of
bichromatized albumen is flowed over the plate. It is next exposed in the
camera, and afterwards washed with water, in order to dissolve all the
albumen which has not been rendered insoluble by the luminous action; it
is then treated with spirit of turpentine, which dissolves all those parts
of the layer of bitumen that have become exposed. The plate can now be
attacked directly by water acidulated with from four to six per cent of
nitric acid. The great advantage of this method consists in the high
sensitiveness of the bichromatized albumen, at the same time preserving
the solid reserve produced by the bitum