on Glue.

Of the use of _common glue_ very little need be said; it should always
be prepared in a gluepot or double vessel, to prevent its being
burned, which injures it very materially. The chief objection to the
use of this contrivance is, that it renders it impossible to heat the
glue in the inner vessel to the boiling point; this, however, can be
obviated by employing in the outer vessel some liquid which boils at a
higher temperature than pure water, such as a saturated solution of
salt (made by adding one-third as much salt as water). This boils at
224 deg. Fahr., 12 deg. above the heat of boiling water, and enables the glue
in the inner vessel to be heated to a much higher temperature than
when pure water is employed. If a saturated solution of nitre is used,
the temperature rises still higher.

2493. Diamond Cement.

Soak isinglass in water till it is soft; then dissolve it in the
smallest possible quantity of proof spirit, by the aid of a gentle
heat; in two ounces of this mixture dissolve ten grains of ammoniacum,
and whilst still liquid add half a drachm of mastic, dissolved in
three drachms of rectified spirit; stir well together, and put into
small bottles for sale.

_Directions for Use_.--Liquefy the cement by plunging the bottle in
hot water, and use it directly. The cement improves the oftener the
bottle is thus warmed; it resists the action of water and moisture
perfectly.

2494. Rice Flour Cement.

An excellent cement may be made from rice flour, which is at present
used for that purpose in China and Japan. It is only necessary to mix
the rice flour intimately with cold water, and gently simmer it over a
fire, when it readily forms a delicate and durable cement, not only
answering all the purposes of common paste, but admirably adapted for
joining together paper, cards, &c., in forming the various beautiful
and tasteful ornaments which afford much employment and amusement to
the ladies. When made of the consistence of plaster-clay, models,
busts, bas-relievos, &c., may be formed of it; and the articles, when
dry, are susceptible of high polish, and are very durable.

2495. Using Egg.

The white of an egg, well beaten with quicklime, and a small quantity
of very old cheese, forms an excellent substitute for cement, when
wanted in a hurry, either for broken china or old ornamental glassware.

2496. Cement for Broken