Without enumerating all the chemical properties of lime, it will be sufficient to remark, that it is composed of calcium and oxygen, and, when slaked with water, will evolve caloric in a free state, while the water solidifies or combines with the lime; that it forms with water, a solid hydrate, an example of which combination is afforded by the preparation of mortar; that it dissolves in water, and forms lime-water, and is slaked by exposure to the air, absorbing, at the same time, carbonic acid; that it unites with acids, like other salifiable bases, and forms salts, some of which are soluble in water, and others not; that it deprives the alkalies of carbonic acid, and renders them caustic, being itself changed into a carbonate; and, that it unites with sulphur and phosphorus, forming a sulphuret and phosphuret, and, also, with hydroguretted sulphur, and sulphuretted hydrogen, forming a hydroguretted sulphuret, and a hydro-sulphuret. When limestone, marble, &c. are burnt in a kiln, the carbonic acid is expelled, and quicklime formed. Quicklime and lime, chemically speaking, are synonimous terms. The fluor, or Derbyshire spar, is a fluate of lime. When this substance is distilled in a leaden retort, with sulphuric acid, we have sulphate of lime, and fluoric acid gas, called by some hydro-fluoric acid. This acid, when received in water, is used to etch on glass, in the same manner as nitric acid on copper; and while applied in a liquid state, or in that of gas, it acts on the glass, by combining with the silicon, and is changed from the hydrofluoric, into the silicated fluoric acid. If, instead of employing a leaden vessel, we make use of a glass retort, or introduce powdered glass or silica, into the leaden vessel, in either case, we obtain another acid, which we have just mentioned, the silicated fluoric acid; in consequence of the union of silicon with the supposed radical of the fluoric acid, known by the name of fluorine. Quicklime is occasionally, though but rarely, employed in fire-works. That it increases the strength of powder, is asserted by Dr. Bayne. See Gunpowder. Its use in making slow match, along with other substances, is given in the article on that subject. _Sec. XLI. Of Lapis Calaminaris._ That some of the ores of zinc are employed in fire-works, is evident from the use of lapis calaminaris, or calamine stone, which is an impure carbonate of zinc. Calamine should be finely pulverized and sifted. As zinc gives a particular colour to flame, (see _zinc_), its carbonate may also communicate a colour, and, under particular circumstances, may produce a great variety, and, therefore, in such cases, be preferable to the zinc itself. It is one of the ingredients in the _dead fire_ for wheels, which is composed of lapis calaminaris, saltpetre, brimstone, and antimony.