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6tte other tree. Thefe, though very exact, and beautiful, could have no analogy with the fubftances out of which the falts were formed, the fir and pine kind yielding fo little fixed fait, that they are never employed for this purpofe, and the fal armoniac belonging to no vegetable production at all. The fame procefs repeated feveral times afterward, both with the fame falts, and with others of the fame nature, never ar- rived at this perfection ; and the whole beauty of this was loft while tiie fpectarors were gazing on it, by the fublimation of more of the fait, which filled up all the interftices, and de- itroyed the figure. Phil. Tranf. N°. 105. The curious in thefe refearches, who would extend the ufe of thefe falts to the compofing fal armoniac, and many other purpofes, for the ufe of dyers, braziers, apothecaries, che- miifs, tjfe. may confult Boerhaave's hiftory of vegetable pu- trefaction, and his account of fal armoniac, and compare with them the papers of Lcmery and Geoffroy, in the memoirs of the Paris academy, on the fubject of the preparation of fal ar- moniac in the Levant, and the imitation of it in other coun- tries. VOLCANO (Cycl.)— Dr. Lifter is of opinion, that all the Volcanoes in the world are owing to that inflammable mineral called pyrites, or snundic, a fubdance confining of fulphur and iron, and found in great plenty in all thofe mountains where the Volcanoes are found to break out.
The quantities of fulphur continually fublimed in thefe moun- tains, in the fame manner as the common fulphur is feparated by artificial fire from the pyrites in Germany, feems to prove this ; and what farther evinces it, is, that the black or purple cinders thrown out of thefe Volcanoes in their meft violent eruptions, and wholly differing from the calcined Hones or pumice, will he attracted by the magnet, and fhew that the whole is very much the fame with that caput mortuum of the common pyrites, out of which we have extracted or burnt away the fulphur.
That thefe Volcanoes were all kindled of themfelves, at or near the time of the creation, is probable ; becaufe there is at pre- fent but a certain number of them known, and thefe have all continued burning at all times, from the earlieft hiftory, and none of them have ever been extinguithed wholly, or proba- bly ever can be, any other way than by the fubmerfion of the Whole into the fea. That they originally kindled of them- felves, by means of the pyrites they contain, is very proba- ble, becaufe we find that the pyrites will kindle of itfelf, and there is no other apparent caufe for their kindling ; for if we fuppofe the fun to have done it, the mountain Hecla mould have been excufed, as {landing in a northerly and colder cli- mate ; yet this, by all hiftory, feems to have burnt as long as the others.
That they were at firft fired my man, is not probable, becaufe it would not be eafy to conceive how that mould be effected, if attempted ; and they are in places the Ieaft likely ever to have been the habitations of man, being in the tops of the higheft mountains. If we attribute the kindling them to lightnings, or earthquakes, we favour the Doctor's fyllem as much as in his own way ; for all thefe he deduces alfo from tbe breath or exhalations of the fame mineral, the pyrites, which when fired under ground make earthquakes, 'when in the air lightnings.
No fubjeft in the whole mineral kingdom is fo proper for the keeping up a fire for the many ages thefe mountains have been burning, as the pyrites. Nothing is fo lading a fuel, and, in general, other fuels become more or lefs lading, as they partake more or lefs of its nature. Scotch coals have more of the bitumen in them, and lefs of the pyrites than others, and therefore they burn away quickly, and leave only white allies, without any remains of the pyrites. The common Newcaftle coal burns more {lowly away, becaufe it contains a far larger portion of the pyrites mixed with its bitumen, as is found by the fulphureous fmell it yields in burning ; and the Sunderland coal, which contains mod of all of this mine- ral, burns with a more fulphureous fmell indeed, but fo (low- ly, that it is faid proverbially to make three fires. This burns to a heavy reddifh cinder, much refembling the caput mor- tuum of the pyrites, or the flags caft out of the burning moun- tains, and contains fo much iron, that it is freely attrafted by the magnet.
There is, in Ireland, a fort of coal more rich in the pyrites than all thefe, and feeming indeed to confift in great part of it. This, confequently, keeps up a greatly more durable fire than any of the others, and will remain twenty-four hours red-hot in the fire, without changing its fhape. The rife of the breath or effluvia of thefe pyrites into the air, and their taking fire there, may very naturally caufe lightning and thunder there ; and it is remarkable, that even the feemingly miraculous accounts of dorms of throwing down iron-dud or iron-dones, indead of hail or rain, does not wholly difcredit this fyftem ; for iron being one part of the condituent matter of the pyrites, it is poffible it may have been raifed in a vapour with it, and when the fulphureous part was fired and burnt away, it may have again concreted into a folid form, and in that form have fallkn to the earth again. Phil. Tranf. N». 157.
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The neceffity of a fubterranean fibe is argued from various inftances, and from various phenomena. The places to which this fire is brought up to our view, are generally the tops of mountains j where it may have its free couife through their cavities, and burn a length of time, without doing injury to any body.
The fubterrancan lire could not exift without a communica- tion with the external air ; and thefe Volcanoes in the moun- tains are the fpiracles or air holes at which it receives the ne- ceffary fupplics of it, and by which it communicates with it as much as is neceffary for its fupport. By thefe the necefLry magazines of fire are kept in a due ftate, and by thefe they difcharge the fmoak and foulneffes with which they would otherwife be choaked up and extingmfhed. Europe affords five principal openings of this kind. Of thefe, the chief is /Etna, in the ifland of Sicily, zFolccmo famous in all hiftories. The next to this is Vefuvius, near Naples; then the Strongylus, and fome others of lefs note in the Lipa- nne iflands ; Hecla in the frozen region of Iceland, and the Chimera in Greece. The Volcanoes of Afia are not lefs nu- merous i there are feveral in the mountains ofPerfia, and in the ifland of Ormuz. The pic of Adam, in the ifland of Ceylon, alfo burns at certain times : But the principal Volca- noes of this part of the world are in the Philippine and Molucca iflands. Java and Sumatra alfo furnilh fome in the center of their largeft mountains. The ifland of Ternate affords alfo a Volcano on the top of a mountain very difficult ofaecefs, hue opening with a vaft mouth, and very terrible when it burns. The feveral violent eruptions of this mountain have given it, within the mouth or Crater, the appearance of an amphi- theatre, formed for holding people at the time of fome public fhew, feveral circles appearing in it one above another, found: with a fort of regularity that is furprifing. In Japan there are very numerous inftances of the ufe that mountains ferve to on this occafion, many of the higher mountains of that ifland burning almoft continually ; and the little iflands which -lie fcattered about in the fame fea have alfo many of them fpira- cles of the fame kind in the tops of the mountains, feen prin- cipally in the night, when the abfence of the fun's rays gives their faint fire leave to appear.
Whatever may be the number of thefe Volcanoes in Afia, there is no part of the word that yields fo many as America. In the kingdom of Chili alone there are fourteen very confidence Volcanoes,, all placed In a regular order one by the other ; and not a lefs number in Peru ; thefe all burft forth from the fum- mits of thofc vaft mountains the Ancles. In New Spain there are three very formidable for the ficrcenefs of their burning. The mofi extreme parts -of the northern world are not free from thefe ftore-houfes of fire. Authors tell us of no lefs than four of them in the mofi: northern parts of Tartary ; and we know that Greenland, ard all the neighbouring country, has them. The Volcanoes of the Terra del Fucgo are very well known, and it is indeed the general opinion, that far- ther north than we have yet penetrated there may be very- many undifcovered ones i and fome authors have gone fo far as to declare, that, were the cold no prevention, we fhould not be able to. come much nearer than we do to the fouth- ern pole, for the number and fiercenefs of the burning moun- tains.
People who fee but a little way into the ceconomy of the uni- verfe, are apt to blame the author of nature for placing fo many of thefe Volcanoes in the habitable parts of the world, and expofing fo many of the human fpecies to perifh by them ; but when the fyftem of nature is more clearly feen into, we find all the reafon in the world to admire and adore the good- nefs of providence in the difpofition of thefe very things. When it proved neceffary to the ends of the creation of the world, that a fire fhould be kept up within it, where could that be fo well kept from doing us injury, as deep in the cen- tral parts ; and when it was neceflisry that this fire fhould have fpiracles, or air-vents ; where could they be placed more out of our way, than in the tops of the higheft mountains, as we conftantly and regularly find they are. Thefmoak, cinders, and other recrements of the fuel that fupports the fubterranean fire, are by this means difcharged far above the heads of the . inhabitants, and out of the way of doing them any harm j whereas, had thefe openings been on plain ground, the whole air the neighbouring nations breathed would have been in- fected with the flench, and ficknefs bred with it, befide the danger of firing their houfes and towns, and fpoilmp- their cultivated lands with the vaft quantities of cinders,°afhes, and other matters thrown up, which-, as it is, frlling on the barren fides of the mountains, do no harm to any thing. The provident placing of thefe mountains near the fea, either in iflands, or on the coafts of continents, is alio a great benefit to mankind, as the redundant matter difcharged is thrown into the fea, and as there are, in general, higher winds nearer the fea than farther from it, by which the Vmoak, and with it the malignant vapours of the burnt minerals, aredifperfed in the upper region of the air, and never defcend in fuch quanti- ties as to do harm to the neighbouring inhabitants. This giving vent to the fubterranean pyrophylacta , feems one of the great ends of the origin of mountains, and the
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