How To keep plaster of Paris from setting too quickly

Sift the plaster into the water, allowing it to soak up the water without stirring, which would admit the air, and cause the plaster to set very quickly. If it is desired to keep the plaster soft for a much longer period, as is necessary for some kinds of work, add to every quart of water one-half teaspoonful of common cooking soda. This will gain all the time that is needed.

How To remove grease stains from marble

Mix soft soap 1 1/2 parts, Fuller's earth 3 parts, potash 1 1/2 parts, and boiling water. Cover the grease spots with this mixture, letting it remain a few hours.

How To keep paste from spoiling

Add a few drops of oil of clove.

How To make a cement that will hold when all others fail

Melt over a slow fire equal parts of rubber and pitch. When wishing to use it, melt and spread it on a strip of strong cotton cloth.

Bath for cleaning sheet copper that is to be tinned.

Pour into water sulphuric acid, until the temperature rises to about blood heat, when it will be about right for pickling purposes.

How To tin sheet copper after it has been well cleaned.

Take it from the bath. If there are any spots which the acid has failed to remove, scour with salt and sand. Then over a light charcoal fire heat it, touching it with tin or solder, and wipe from one end of the sheet to the other with a handful of flax, only going so fast as it is thoroughly tinned. If the tinning shows a yellowish color, it shows there is too much heat, which is the greatest danger, as tinning should be done with as little heat as is necessary to make the metal flow. When this is done, rinse off in clean water and dry in sawdust.

How To give copper a red appearance as seen on bath boilers

After the copper has been cleaned, rub on red chalk and hammer it in with a planishing hammer.

How To tin soldering copper with salammoniac

It will be found very handy to have a stick of salammoniac in one's kit for tinning purposes. After filing the heated copper bright, touch the copper with the salammoniac and afterward with a stick of solder. The solder will at once flow over the entire surface. In this there is but one danger, the too great heating of the copper, in which case the burned salammoniac will form a hard crust over the surface. Tin with as little heat as possible. Salammoniac will be found of great value in keeping the soldering copper in shape by frequently rubbing the tinned point with it.

How To Keep Soldering Coppers in Order While Soldering with Acid

In a pint of water dissolve a piece of salammoniac about the size of a walnut. Whenever the copper is taken from the fire, dip the point into the liquid, and the zinc taken from the acid will run to the point of the copper and can then be shaken off, leaving the copper bright.