in physics, a fluid; or, more properly, the flate of a body that was before hard or solid, but is now reduced by fusion or fire into a state of fluidity.
FLUOR Acid. See Chemistry-Index.
FLUOR Albus. See Medicine-Index.
FLUOR-Spar, or Blue John, called also fluxing spars, vitreous or glass spars, are a genus of fossils composed of calcareous earth united with an acid of a peculiar kind, of which an account is given under Chemistry; see that article, per Index at Fluor acid.
They are little harder than common calcareous spars, and do not strike fire with steel; nor do they effervescce with acids either before or after calcination. When exposed to a strong fire, they crack and split in pieces, but do not melt without a violent heat. Engenbroth informs us, that all of them which he tried melted pretty easily before the blow-pipe; but he was obliged to take great care to prevent them from flying away before they were thoroughly heated. Their specific gravity is from 3144 to 3175: notwithstanding the difficulty with which they are fused by themselves, however, they melt very readily in conjunction with other earths; running into a corrosive glass which dissolves the strongest crucibles, unless some quartz or fire-clay be mixed in their composition. When gradually heated, they give a phosphorescent light; but lose this property when made red-hot. Those which are coloured, particularly the green ones, give the strongest light. They melt easily with borax, and next to that with the microcosmic salt, neither of them making any effervescence. They dissolve in acids when boiling, particularly aqua-regia; and the solutions are precipitated by an alkali even though cold, but not so completely. M. Magellan informs us, that he has frequently dissolved them in boiling vitriolic acid in order to get that of fluor in an aerial state. There are three species.
1. The indurated fluor is solid, and of an indeterminate figure, of a dull texture, semitransparent, and full of cracks in the rock. It is of a white colour.
2. Sparry fluor. This has nearly the figure of spar; though, on close observation, it is found less regular; nothing but its glossy surface giving it the resemblance of spar. It is found of various colours, viz. white, blue, green, pale-green, violet, and yellow.
3. The crystallized fluor is of four kinds. 1. Having an irregular figure, of a white, blue, or red colour. 2. Crystalized in cubes, of a yellow or violet colour. 3. Of a polygonal spherical figure, white or blue coloured. 4. Of an octahedral figure, clear and colourless.
The principal use of fluors is for smelting ores, where they act as very powerful fluxes, and on this account are much valued. They are found in various countries, particularly Sweden, and some other northern countries of Europe. From this quality of melting easily in combination with other earthy matters, they have got the name of fluors. "The resemblance between the coloured fluors and the compositions made of coloured glass (says Cronstedt), has perhaps contributed not only to the fluors being reckoned of the same value with the coloured quartz crystals, by such collectors as only mind colour and figure, but to their also obtaining a rank among the precious stones in the apothecaries and druggists shops." M. Fabroni observes, that this combination of calcareous earth with the sparry acid is almost always transparent; it often crystallizes in regular cubes, sometimes single from one line to two inches in diameter, and sometimes of an indeterminate figure. They are sometimes of a blue colour; others are purple like amethysts; some are of a brown colour, others opaque. M. Magellan says, that fluors in general have this singular property, that on being melted by the flame of the blow-pipe, together with gypsum, the lead resulting from both is all formed with facets on the outside; but if melted with terra ponderosa, its surface is quite round or spherical.
M. Margraff has made experiments in order to discover the nature of these stones. He ascertained the above-mentioned distinctions between them and the gypseous spars; and therefore infers, that they are not compounded of vitriolic acid with calcareous earth. He observed singular appearances on mixing them with vitriolic and other acids, and subjecting the mixtures to distillation.
Eight ounces of the powder of a green fluor being mixed with an equal weight of pure oil of vitriol, and distilled together with a graduated heat, yielded, after the watery part of the acid had passed, a fine white sublimate, which arose and adhered to the neck of the retort, and even passed into the receiver. The first parts of this sublimate which arose appeared like butter of antimony; and, like this butter, they melted by the heat of a live coal brought near the neck of the retort; but the parts which arose towards the end of the operation, with the greatest degree of heat, could not be melted by that heat. The retort being broken, a residuum was found weighing 12 oz. Hence 4 oz. of oil of vitriol remained united with the spar. The bottom of the retort was observed to be pierced with holes. Lastly, the liquor which had passed into the receiver and the white sublimate, had very sensibly a sulphurous smell. The sublimate, triturated a long time in a mortar with hot distilled water, dissolved, and passed thro' a filter. To the filtrated liquor some fixed alkali being added, a precipitate was formed; which being well washed and dried, was readily melted by fire into a mass resembling porcelain. The same excellent and accurate chemist produced the same effects upon this stone, by substituting, instead of the vitriolic acid, the nitrous, marine, phosphoric, or the concentrated acetic acids.
FLUOR Albus or Uterinus, in medicine, a kind of flux incident to women, popularly called the whites. See Medicine-Index.