ally confused by too great a
profusion of treatment is the art of cementing glass to other
substances.

The following methods will be found to work, subject to two
conditions:

(1) The glass must be clean;

(2) it must be hot enough to melt the cement.

For ordinary mending purposes when the glass does not require to be
placed in water (especially if hot) nothing is better than that kind
of glue which is generally called "diamond cement." This may be
easily made by dissolving the best procurable isinglass in a mixture
of 20 per cent water and 80 per cent glacial acetic acid--the exact
proportions are not of consequence.

First, the isinglass is to be tightly packed into a bottle with a wide
neck, then add the water, and let the isinglass soak it up.
Afterwards pour in the acetic acid, and keep the mixture near 100 deg.C.
for an hour or two on the water bath--or rather in it. The total
volume of acetic acid and water should not be more than about half of
the volume of isinglass when the latter is pressed into the bottle as
tightly as possible.

The proper consistency of the cement may be ascertained by lifting a
drop out of the bottle and allowing it to cool on a sheet of glass.
In ten minutes it ought not to be more than slightly sticky, and the
mass in the bottle, after standing a few hours cold, should not be
sticky at all, and should yield, jelly-like, to the pressure of the
finger to only a slight degree. If the glue is too weak, more
isinglass may be added (without any preliminary soaking).

A person making the mixture for the first time almost always gets it
too weak. It is difficult to give exact proportions by weight, as
isinglass and gelatine (which may replace it) differ greatly in
quality. This cement is applied like glue, and will cement nearly
anything as well as glass. Of course, as much cement as possible must
be squeezed out of any joint where it is employed. The addition of
gums, as recommended in some books, is unnecessary.

Ordinary glue will serve perfectly for cementing glass to wood.

"Chipped glass" ware is, I understand, made by painting clean glass
with glue. As the glue dries and breaks by contraction, it chips off
the surface of the glass. I have never seen this done. In nearly all
cases where alcohol is not to be employed very strong joints may be
made by shellac. Orange shellac is stronger than the "bleached"
variety.

A sine qua non is that the glass be hot enough t