parts
of iron filings, and one half part of sal ammoniac. These are mixed up
with vinegar to make a fluid paste.

To cement Glass to Iron. Use 3 ounces of boiled linseed oil and 1 part
of copal varnish, and into this put 2 ounces of litharge and 1 ounce of
white lead and thoroughly mingle so as to make a smooth paste.

Water-proof Cement. Boiled linseed oil, 6 ounces; copal, 6 ounces;
litharge, 2 ounces; and white lead, 16 ounces. To be thoroughly
incorporated.

To unite rubber or leather to hard substances. One ounce of pulverized
gum shellac dissolved in 9-1/2 ounces of strong ammonia, will make an
elastic cement. Must be kept tightly corked.

For uniting iron to iron. Use equal parts of boiled oil, white lead,
pipe clay and black oxide of manganese, and form it into a paste.

Transparent Cement. Unite 1 ounce of india rubber, 67 ounces of
chloroform, and 40 ounces of mastic. This is to be kept together for a
week, and stirred at times, when it will be ready for use.

To Attach Cloth to Metal. Water 100 parts, sugar 10 parts, starch 20
parts, and zinc chloride 1 part. This must be first stirred and made
free of lumps, and then heated until it thickens.

United States Government Gum. Dissolve 1 part of gum arabic in water and
add 4 parts of sugar and 1 part of starch. This is then boiled for a
few minutes, and thinned down as required.

TO MAKE DIFFERENT ALLOYS.--Silver-aluminum. Silver one-fourth part, and
aluminum three-fourth parts.

Bell-metal. Copper, 80 parts; tin, 20 parts. Or, copper, 72 parts; tin,
26 parts; zinc, 2 parts. Or, copper 2; 1 of tin.

Brass. Copper, 66 parts; zinc, 32 parts; tin, 1 part; lead, 1 part.

Bronzes. Copper, 65 parts; zinc, 30 parts; tin, 5 parts. Or, copper, 85
parts; zinc, 10 parts; tin, 3 parts; lead, 2 parts.

German Silver. 52 parts of copper; 26 parts zinc; 22 parts nickel.

For Coating Mirrors. Tin, 70 parts; mercury, 30 parts.

BOILER COMPOUNDS.--To prevent scaling. Use common washing soda, or
Glauber salts.

TO DISSOLVE CELLULOID.--Use 50 parts of alcohol and 5 parts of camphor
for every 5 parts of celluloid. When the celluloid is put into the
solution it will dissolve it.

To Soften Celluloid. This may be done by simply heating, so it will
bend, and by putting it in steam, it can be worked like dough.

CLAY MIXTURE FOR FORGES.--Mix dry 20 parts of fire clay, 20 parts
cast-iron turnings, one part of common salt, and 1/2 part sal ammoniac,
and then add wate