Stir the lime into the warm solution of sugar and water. Keep it boiling and stir it often for one hour. Pour off the liquid from the lees of the lime. This gum also admits of modifications. One of these is the well-known Syndetikon, which is made as follows:—To fifteen parts of the sugar and lime solution add three of good glue, leaving them to soak for twenty-four hours; warm gradually, and frequently stir, till the glue is dissolved. Then let it boil for a few minutes. This makes a good plain cement, which serves to unite paper, leather, glass, or porcelain. It, however, spots or changes colour in paper, &c.
A general cement, which may be used for joining metal and glass, stone, tiles, &c., is thus made:—
| Plaster of Paris | 21 |
| Iron filings | 3 |
| Water | 10 |
| White of eggs | 4 |
The general mending cement so commonly sold consists of nothing but—
| Gum-arabic | 1 |
| Plaster of Paris | 3 |
This must be mixed with water when used. It does not, however, resist the action of hot water.
A cement which resists acids is made as follows:—Indiarubber is dissolved in double its weight of linseed-oil, and kneaded to a dough with white bolus. Should the cement harden too quickly, add to it a little litharge.
Indiarubber cement for chemical apparatus:—
| Indiarubber | 8 |
| Tallow | 2 |
| Linseed-oil | 16 |
| White bolus | 3 |
This does not resist high temperature, but is good against acids.