A cement for zinc, especially for ornaments and small work:—In ten parts by weight of silicate of soda (solution) stir two parts of cleansed chalk and three of zinc in powder. This is kneaded for some time into a putty, with which defects, roughnesses, &c., can be remedied. After twenty-four hours, when polished with agate, this cement has all the appearance of zinc.
It may be observed that other metals in fine powder may be substituted for the zinc, and that with bronze powders, oxides of metals, and indeed with all the range of painters’ colours, combinations may be formed of infinite application in the arts. According to Lehner the silicate of soda should be of 33°.
A specially strong and valuable cement, capable of many uses in metal, wood, glass, or china, or to fasten glass to metal, is made as follows:—Take best purified litharge, stir it with glycerine until it becomes a thin homogeneous mass, which in less than an hour will become a very hard mass, which is of almost universal application. It is not affected by water, and resists the action (according to Lehner) of almost all acids, the strongest alkalies, as well as etherised oils and the fumes of chlorine and alcohol. The surfaces which are to be united with it must first be covered with pure, thick glycerine.
It will readily occur to the reader that in or to this, as in every recipe given in this book, modifications, alterations, and additions can be made, of very great value, adaptable to a great variety of substances. It is to be observed that in such cases as this, where one cannot be sure of the exact result, it is best, e.g., to first experiment with a very little finest pulverised oxide of lead with the glycerine.
Another form of this powerful metallic cement is given as follows:—
| Concentrated glycerine | ½ | litre | |
| Litharge | 5 | kilogs. |
To make a cement to fill or close joints in zinc-work:—Soak three parts by weight of glue in water, pour off the superfluous water, dissolve the glue in warm water, stir into it six parts of slacked lime and one of flowers of sulphur.
When ironwork, as, for instance, window-bars, is to be set in stone, the following is commended as taking a firm hold:—
| Calcined gypsum | 30 |
| Finely powdered iron | 10 |
| Vinegar | 20 |
The following recipes, though I have found many of them in other works, are here taken, with acknowledgment, from Lehner, as his proportions are invariably accurate, or confirmed by experiment.