Creosote dissolves several salts, particularly the acetates, and the chlorides of calcium and tin; it reduces the nitrate and acetate of silver. It also dissolves indigo blue; a remarkable circumstance. Its action upon animal matters is very interesting. It coagulates albumen, and prevents the putrefaction of butcher’s meat and fish. For this purpose these substances must be steeped a quarter of an hour in a weak watery solution of creosote, then drained and hung up in the air to dry. Hence Reichenbach has inferred that it is owing to the presence of creosote, that meat is cured by smoking; but he is not correct in ascribing the effect to the mere coagulation of the albumen, since [fibrine] alone, without creosote, will putrefy in the course of 24 hours, during the heats of summer. It kills plants and small animals. It preserves flour paste unchanged for a long time.
Creosote exists in the tar of beech-wood, to the amount of from 20 to 25 per cent., and in crude pyrolignous acid, to that of 11⁄2.
It ought to be kept in well-stoppered bottles, because when left open, it becomes progressively yellow, brown, and thick.
Creosote has considerable power upon the nervous system, and has been applied to the teeth with advantage in odontalgia, as well as to the skin in recent scalds. But its medicinal and surgical virtues have been much exaggerated. Its flesh-preserving quality is rendered of little use, from the difficulty of removing the rank flavour which it imparts.
CRUCIBLES; (Creusets, Fr.; Schmelztiegel, Germ.) are small conical vessels, narrower at the bottom than the mouth, for reducing ores in docimasy by the dry analysis, for fusing mixtures of earthy and other substances, for melting metals, and compounding metallic alloys. They ought to be refractory in the strongest heats, not readily acted upon by the substances ignited in them, not porous to liquids, and capable of bearing considerable alternations of temperature without cracking; on which account they should not be made too thick. The best crucibles are formed from a pure fire clay, mixed with finely ground [cement] of old crucibles, and a portion of black-lead or graphite. Some pounded coak may be mixed, with the plumbago. The clay should be prepared in a similar way as for making pottery ware; the vessels after being formed must be slowly dried, and then properly baked in the kiln. Crucibles formed of a mixture of 8 parts in bulk of Stourbridge clay and cement, 5 of coak, and 4 of graphite, have been found to stand 23 meltings of 76 pounds of iron each, in the Royal Berlin foundry. Such crucibles resisted the greatest possible heat that could be produced, in which even wrought iron was melted, equal to 150° or 155° Wedgewood; and bore sudden cooling without cracking. Another composition for brass-founding crucibles is the following:—1⁄2 Stourbridge clay; 1⁄4 burned clay cement; 1⁄8 coak powder; 1⁄8 pipe clay. The pasty mass must be compressed in moulds. The Hessian crucibles from Great Almerode and Epterode are made from a fire clay which contains a little iron, but no lime; it is incorporated with siliceous sand. The dough is compressed in a mould, dried, and strongly kilned. They stand saline and leaden fluxes in docimastic operations very well; are rather porous on account of the coarseness of the sand, but are thereby less apt to crack from sudden heating or cooling. They melt under the fusing point of bar iron. Beaufay in Paris has lately succeeded in making a tolerable imitation of the Hessian crucibles with a fire clay found near Namur in the Ardennes.
Berthier has published the following elaborate analyses of several kinds of crucibles:—
| Hes- sian. | Beau- fay. | English for Cast Steel. | St. Etienne for Cast Steel. | Glass Pots at Ne- mours. | Bohe- mian Glass Pots. | Glass Pots, of Creu- sot. | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Silica | 70 | ·9 | 64 | ·6 | 63 | ·7 | 65 | ·2 | 67 | ·4 | 68 | ·0 | 68 | ·0 | |
| Alumina | 24 | ·8 | 34 | ·4 | 20 | ·7 | 25 | ·0 | 32 | ·0 | 29 | ·0 | 28 | ·0 | |
| Oxide of Iron | 3 | ·8 | 1 | ·0 | 4 | ·0 | 7 | ·2 | 0 | ·8 | 2 | ·2 | 2 | ·0 | |
| Magnesia | trace | - | - | - | - | trace | trace | 0 | ·5 | trace | |||||
| Water | - | - | - | - | 10 | ·3 | [23] | - | - | - | - | - | - | 1 | ·0 |
[23] This crucible had been analyzed before being baked in the kiln.
Wurzer states the composition of the sand and clay in the Hessian crucibles as follows:—
| Clay; | silica | 10·1; | alumina | 65·4; | oxides of iron and manganese | 1·2; | lime | 0·3; | water | 23 |
| Sand; | 95·6; | 2·1; | 1·5; | 0·8 |