In filing large surfaces of cast-iron, bronze or brass, a file with keen cutting teeth is required; use a new file on such surfaces. On narrow surfaces a file that is partly worn can be used with about as good effect as a new file. When a file is so-called worn out on brass or soft metal, it is in pretty good condition to be used on steel or iron. Many mechanics prefer such files to new ones.
A good lining for stoves may be made by pulverizing old brick, or any fire brick, and mixing with this sufficient clay to make it plastic. Before making a coal fire dry out the water. The coal fire will bake and make a solid fire brick lining of your plastic-back.
Bicarbonate of ammonia and sulphate of soda in strong solution is the best compound to put in bottles for hand-grenades to extinguish fire.
The best flux for hard solders is a soldering fluid consisting of hydrochloric acid (spirit of salt), saturated with zinc. To prepare this flux put 1/2 pint of muriatic acid (also called spirits of salts and hydrochloric acid) into a glass, and add small pieces of clean zinc, which will be dissolved by the acid. Let it stand for several hours, till the acid has ceased to act; then add a small quantity of water, say a wine-glassful, when boiling will recommence. Let it stand undisturbed for a few hours, and again add a small quantity of water. Continue this until the quantity of water added equals that of the acid (1/2 pint). When all action has ceased, add 1 ounce of sal-ammoniac; let it stand twelve hours, then decant the clear liquid into a bottle, which should be kept well fastened when not in use. Throw away the sediment, and add a little sal-ammoniac.
To frost brass and give it a decorative finish, boil the article in potash, rinse in water, plunge in nitric-acid, wash again, then dry in hot sawdust, and give the still hot metal a coat of varnish.
This is done by heating the tinplate until rather too hot to hold; then dip in a mixture of hydrochloric acid, 1; nitric acid, 1; water, 4. Rinse, dry in hot sawdust (which must be from non-resinous wood), and lacquer - the plate being still hot enough to do everything at one operation, as it were.
A good compound for lining furnaces is made of 10 parts of lime and 90 parts of ganister. The lime is first burned and slaked, and the addition of the ganister is made twelve hours afterward. The addition of enough water for the required consistency is then made and the whole intimately mixed. Line the furnace with the compound and dry by making a moderate fire in the furnace.
To galvanize with gold, dissolve a little gold in a mixture of muriatic acid and aqua fortis, and add to it 2 parts of alcohol. Copper immersed in this solution for half an hour will be completely galvanized.
German Britannia metal is composed of:
4 parts Copper. 24 parts Ammonia, 72 parts Tin.
5 parts Zinc,
2 parts Copper, ' 9 parts Antimony, 84 parts Tin, or
6 parts Zinc, 10 parts Copper, 64 parts Antimony, 20 parts Tin.