Soak the gelatine in half a pint of water for four hours. Place in a bottle and heat in a water bath; add the acids, dissolve, add the oil of cloves and sufficient hot water to make a pint, and strain.
To Cement Iron to Iron.
| Powdered cast-iron bore chips60 | parts. |
| Sal-ammoniac2 | parts. |
| Flowers of sulphur1 | part. |
Mix, and stir the mixture into a stiff paste by adding water. Use while fresh.
Cementing Metal to Glass, Stone, Etc.
For attaching metal plates, such as metal letters, etc., to flat sheets of glass or windows, the following is excellent:
| Copal varnish15 | parts. |
| Drying oil5 | parts. |
| Turpentine3 | parts. |
Melt in a water bath, and add 10 parts of slaked lime. The cement commonly used for fastening the tops on kerosene lamps is plaster of Paris, which is porous, quickly penetrated by the kerosene, and readily destroyed. A cement which does not have this defect is made by boiling 3 parts of resin and 1 of caustic soda in 5 of water. This composition forms a soap, which mix with half its weight of plaster of Paris. Use while fresh.