a general name for all calcareous substances when deprived of their fixed air; such as chalk, limestone, oyster-shells, &c. calcined. See Lime, Chemistry, for an account of the properties and combinations of lime.

QUICKSILVER, or Mercury, one of the metals, and so fusible that it cannot be reduced to a solid state but at a degree of cold, equal to 40 below 0 of Fahrenheit's thermometer. For the method of extracting quicksilver from its ore, &c. see Ores, Reduction of. For the various preparations, &c. see Chemistry and Materia Medica Index; and for the natural history of the ores of quicksilver or mercury, see Mineralogy Index.

Mines of quicksilver are very rare, insomuch that, according to the calculations of Hoffman, there is 50 times more gold got every year out of the mines than mercury and its ores. But Dr Lewis, in his notes upon Newmann, says, that Cramer suspects that Hoffman only meant five times instead of 50; but neither the Latin nor the English edition of this author expresses any such thought; on the contrary, he adopts the same opinion; and only adds, that mercury is much more frequently met with than is commonly believed; but being so volatile in the fire, it often flies off in the roasting of ores, and escapes the attention of metallurgists.

According to Newmann, the mines of Idria have produced at the rate of 231,778 pounds weight of mercury per annum; but those of Almaden in Spain produce much more. The chemists of Dijon inform us, that their annual produce is five or six thousand quintals, or between five and six hundred thousand pounds weight. In the year 1717 there were upwards of 2,500,000 pounds of quicksilver sent from them to Mexico, for the amalgamation of the gold and silver ores of that country.

At Guanajuato in Brazil the annual produce of the mines, according to Bomare, amounts to one million of pounds, which are carried overland to Lima, thence to Arica, and lastly to Potosi for the same purpose.

Besides these mines there are others in Brazil near Villa Rica, where such a quantity of cinnabar, and native running mercury, are found near the surface of the earth, that the black slaves often collect it in good quantities, and sell it for a trifling price to the apothecaries; but none of these mines have ever been worked or taken notice of by the owners. Gold naturally amalgamated with mercury is likewise met with in the neighbourhood of that place; and it is said that almost all the gold mines of that country are worked out by simply washing them out with running water, after reducing into powder the hard ores, which are sometimes imbedded in quartzose and rocky matrices.

In the duchy of Deux Ponts and in the Lower Austria the quicksilver flows from a schistose or stony matrix, and is probably, says Mr Kirwan, mixed with some other metal, as its globules are not perfectly spherical. The mines of Friuli are all in similar beds or strata. The metal is likewise found visibly diffused through masses of clay or very heavy stone, of a white, red, or blue colour; of which last kind are the mines of Spain, some of Idria, and of Sicily. Macaegui found fluid quicksilver, as well as native cinnabar and mineral ethiops, near the lake of Trivale in the duchy of Siena; but the quantity was so small as not to be worth the expense of working. On the other hand, the following mines afford profits to the owners after clearing all expenses, viz. those at Kremnitz in Hungary; at Horowitz in Bohemia; Zorge in Saxony; Wolfstein, Stalberg, and Moeschfeld in the Palatinate. Mercury is also brought from Japan in the East Indies; but the greatest part of what is sold in Europe as Japan cinnabar is said to be manufactured in Holland.

Lemery, Por., and others, lay down some external marks by which those places are distinguished where there are mines of quicksilver, viz. thick vapours like clouds arising in the months of April and May; the plants being much larger and greener than in other places: the trees seldom bearing flowers or fruit, and putting forth their leaves more slowly than in other places; but, according to Newmann, these marks are far from being certain. They are not met with in all places where there is quicksilver, and are observed in places where there is none. Abundance of these cloudy exhalations are met with in the Hartz forest in Germany, though no mercury has ever been found there; to which we may add, that though vast quantities of mercurial ores are found at Almaden in Spain, none of the above-mentioned indications are there to be met with.

Native mercury was formerly sought from the mines of Idria with great avidity by the alchemists for the purpose of making gold; and others have showed as ridiculous an attachment to the Hungarian cinnabar, supposing it to be impregnated with gold; nay, we are informed by Newmann, that not only the cinnabar, antimony, and copper of Hungary, but even the vine trees of that country, were thought to be impregnated with the precious metal. Not many years ago a French chemist advertised that he had obtained a considerable quantity of gold from the ashes of vine twigs and stems, as well as of the garden soil where they grew: but the falsehood of these assertions was demonstrated by the count de Lauragais to the satisfaction of the Royal Academy of Sciences.

The reduction of mercury into a solid state, so that Quicksilver it might be employed like silver, was another favourite alchemical pursuit. But all processes and operations of this kind, says Newmann, if they have mercury in them, are no other than hard amalgams. When melted lead or tin are just becoming consistent after fusion, if a stick be thrust into the metal, and the hole filled with quicksilver, as soon as the whole is cold, the mercury is found solid. Macquer informs us, that mercury becomes equally solid by being exposed to the fumes of lead. Maurice Hoffman, as quoted by Newmann, even gives a process for reducing mercury, thus coagulated, to a state of malleability, viz. by repeatedly melting and quenching it in linseed oil. Thus, he tells us, we obtain a metal which can be formed into rings and other utensils. But here the mercury is entirely dissipated by the repeated fusions, and nothing but the original lead is left. Valerius, after mentioning strong soap-leys, or caustic lixivium, and some other liquors proper for fixing quicksilver, tells us, that by means of a certain gradatory water, the composition of which he learned from Creuling de Aureo Vellere, he could make a coagulum of mercury whenever he pleased, of such consistency that great part of it would resist cupellation; but what this gradatory water was, he has not thought proper to lay before the public.