, for if that is inferior and not well cleansed, the product will
have to be unduly charged with alum or some other antiseptic, to make it
keep during the drying process. Weathered glue is that which has
experienced unfavorable weather while drying, at which time it is rather a
delicate substance. To resist damp atmosphere well, it should contain as
little saline matter as possible. When buying the article, venture to
apply your tongue to it, and if it tastes salt or acid, reject it for
anything but the commonest purpose. The same operation will also bring out
any bad smell the glue may have. These are simple and ready tests and are
the ones usually adopted by dealers and large consumers. Another good
test is to soak a weighed portion of dry glue in cold water for
twenty-four hours, then dry again and weigh. The nearer it approaches to
its original weight the better glue it is, thereby showing its degree of
insolubility.

BOOK-BINDERS' GLUE.

To prevent book-binders glue from turning sour, add enough of the raw
salicylic acid in boiling water to keep it soluble. It is also commended
never to keep glue in open pots, but in cylindrical shaped vessels that
admit of tight corking.

HOW TO MAKE A CEMENT FOR GLASS THAT WILL RESIST ACIDS.

To make a cement for glass that will resist acids, the following has been
recommended:--Take 10-1/2 pounds of pulverized stone and glass, and mix
with it 4-3/4 pounds of sulphur. Subject the mixture to such a moderate
degree of heat that the sulphur melts. Stir until the whole becomes
homogeneous, and then run it into molds. When required for use it is to be
heated to 248 deg., degrees, at which temperature it melts, and may be
employed in the usual manner. This, it is said, resists the action of
acids, never changes in the air, and is not affected in boiling water. At
230 deg. it is said to be as hard as stone.

CEMENT FOR LABELS.

1. Macerate 5 parts of glue in 18 parts of water. Boil and add 9 parts
rock candy and 5 parts gum arabic. 2. Mix dextrine with water and add a
drop or two of glycerine. 3. A mixture of one part of dry chloride of
calcium, or 2 parts of the same salt in the crystallized form, and 36
parts of gum arabic, dissolved in water to a proper consistency, forms a
mucilage which holds well, does not crack by drying, and yet does not
attract sufficient moisture from the air to become wet in damp weather. 4.
For attaching labels to tin and other bright metallic su