A cement useful for many purposes, also as a ground for painting, is made as follows:—Take barley and soak it in six equivalents of water for several days, or till the barley expands or sprouts. Throw out the barley, after pressing it. This gives a glutinous liquid, which, combined with pipeclay and white soap, sets hard. It is improved by adding the powder of calcined bone. Barley water may also be used in many other combinations. Gum-arabic and thin glue, dextrine, and fish-glue may be used in its place.
A strong cement for horn or tortoise-shell:—
| Glue (fluid) | 1 | ½ |
| Sugar-candy | 3 | |
| Gum-arabic | ¾ |
The two latter to be dissolved in six parts of water.
Another for the same:—Take strong lime-water; combine it with new cheese. The latter is to be mixed with two parts of water, so as to form a soft mass. Pour into this the lime-water, but see that there is no solid cheese in it. This will form a liquid which can be used as a cement.
Cat-gut, which is, however, made from the intestines of sheep, &c., is of great service in some kinds of repairing, owing to its strength. It can be made into very small cord, which will sustain a man.
Very strong cords for fishermen are also said to be made by taking silkworms just before they spin, cutting them open, and using the silk, which is then found in a solid, longish lump, and which can be artificially drawn out into any shape. It is probable that the silk in this state could be thinned and applied in combination with fibre to produce useful results. It is also probable that this substance, or the silk en masse, could be used for mending silk fabrics in many ways. It could be produced very cheaply, because the greatest expense in manufacturing silk is the reeling, winding, and spinning the thread.
An incredibly strong and serviceable silk is spun by the elm-worm, which can be raised in any quantities wherever elm-trees abound. This is much cultivated in China, and it is said that garments made of its silk descend from father to son. It is several times larger than the silkworm, and survives even the severe winters of Canada. It would be much easier to raise than the delicate bombyx, or common silkworm. It is worth noting that a man can carry easily in his pocket fifty yards of cat-gut or elm worm silk cord strong enough to sustain his weight, which is very useful for travellers to know, since it is useful to mend harness or tether horses.
To soften Horn.—This material can be softened so as to bend in hot water. It requires long boiling. According to Geissler, a horn can be moulded to shape by steeping the horn for two or three days in half a kilogramme of black alicant, 375 grammes of newly calcined lime, and 2 litres (two full quarts) of hot water. Should the mixture assume a reddish colour it is all right; if not, add more alicant and lime. After the horn has been moulded, dry it in well-dried common salt. Horn shavings and filings are made into a paste, which hardens by being in a strong solution of potash and slacked lime, in which it becomes jelly-like and can be moulded. This must be subjected to pressure to expel the moisture. By adding a little glycerine its brittleness is much diminished.
Artificial Bonework.—Reduce the bone or ivory to a very fine, flour-like powder, mix it very thoroughly with the white of eggs, and a very hard and tough mass will be the result. This can be turned and highly polished. This is improved in hardness and quality by grinding the mass again and subjecting it to heat and pressure (Die Verarbeitung Hornes, &c., von Louis Edgar Andés; Vienna, 1892).