ALABASTER, in natural history, a species of that genus of stones whose base is calcareous earth. It differs from marble in being combined, not with the aerial, but with vitriolic acid; therefore, when mixed with any acid, no effervescence appears. It is soluble in about 500 times its weight of water at the temperature of 60. It is fusible alone in a long-continued porcelain heat, or by the blow-pipe. Specific gravity 1.87. Texture granular, with shining particles. In composition, and consequently in its chemical properties, it does not differ from gypsum, selenite, and plaster of Paris.
There are three species of alabaster. 1. The snow-white shining alabaster, or lygdinum of the ancients, is found in Taurus, in pieces large enough to make dishes, or the like. It cuts very freely, and is capable of a fine polish. 2. The yellowish alabaster, or phen-
gites of Pliny, is found in Greece; and is of a soft Alabaster. loose open texture, pretty heavy, and nearly of the colour of honey. This species has likewise been found in Germany, France, and in Derbyshire in England. 3. Variegated, yellow, and reddish alabaster. This species is the common alabaster of the ancients, and is so soft that it may be cut with a knife: It is remarkably bright, and almost transparent; admits of a fine polish, and consists of large angular sparry concretions. It is not proof against water; it ferments violently with aqua-fortis, and burns to a pale yellow. The colour of this species is a clear pale yellow resembling amber, and variegated with undulated veins; some of which are pale red, others whitish, and others of a pale brown. It was formerly brought from Egypt, but is now to be met with in several parts of England. The alabasters are frequently used by statuary for small statues, vases, and columns. After being calcined and mixed with water, they may be cast in any mould like plaster of Paris. See GYPSUM.
Alabaster, Mr Boyle observes, being finely powdered, and thus set in a basin over the fire, will, when hot, assume the appearance of a fluid, by rolling in waves, yielding to the smallest touch, and emitting vapour; all which properties it loses again on the departure of the heat, and discovers itself a mere incoherent powder. The fineness and clearness of this stone renders it in some measure transparent; whence it has been sometimes also employed for windows. There is a church at Florence still illuminated by alabaster-windows; instead of panes of glass, there are slabs of alabaster near 15 feet high, each of which forms a single window, through which the light is conveyed. The countries in Europe which abound most in alabaster are Germany, toward Coblenz; the province of Maconnois, in the neighbourhood of Cluni in France; Italy, toward Rome; where that of Montaout is particularly remarkable not only for its whiteness, but also for the bigness of its blocks, some of which are so large, that statues as big as the life may easily be cut out of them. F. Labat, in his journey to Italy, observes, that there are quarries of alabaster in the neighbourhood of the village called de la Tossa, near Civita Vecchia: there is also alabaster to be found in some places of Lorraine; but it is not much esteemed. A new manufacture of basso relievos, from a singular species of factitious alabaster, has been some time ago established by M. Letapie, at the baths of St Philip in Tuscany. The stream at these baths deposits a peculiar kind of sand, which, when collected and condensed in the cavities of any body employed to oppose its current, acquires the nature, hardness, and colour of alabaster, and assumes the forms of those cavities in which it is thus lodged.