VOLCANO. 



the greateft and moft copious ever known. It happened at 

 the top of a hill, fituated at the north point of Taman, near 

 tlie bay of the fame name. The appearance of the place 

 fccms to indicate that there had been a fimilar eruption at a 

 remote period, for the ground that was not covered over by 

 the lail eruption, is of the fame nature as the more recent 

 fediments, being the fame foil, with the difference only 

 which vegetation and atmofplieric influence muft neceffarily 

 produce. 



The place where the new gulf opened was a pool where 

 the fnow and rain-water ufually remained for a long time. 

 The explofion took place with a noife hlce that of thunder, 

 and with the appearance of a mafs of fire in the form of a 

 fheaf, which lafted only about half an hour, accompanied by 

 a thick fmoke. The ebulhtion, which threw up a part of 

 the liquid mud, lafted till next day, after which the mud con- 

 tinued running over flowly, and formed fij^ ftreams, which 

 made their way from the top of the hill to the plain. The 

 body of mud collefted by thefe ftreams is from fix to ten 

 feet deep, and may be reckoned more than a hundred thou- 

 fand cubic fathoms ! In July, the time when M. Pallas 

 vifited the place, the furface of thofe beds of mud was dry, 

 extremely uneven, and cracked like clayey ground. The 

 gulf that had vomited them was ftopped up with the mud, 

 which was likewife dry. It was not dangerous to walk 

 over it, but it was frightful, as the horrid bubbhng, which 

 was then ftill heard in the interior of the hill, (hewed that it 

 was not fo tranquil as at the furface. The mud thus dif- 

 charged is always a foft clay of a blueifh-afh colour, every 

 where of the fame nature, mixed with brilliant fparks of 

 mica, and with fragments of marly, calcareous and fandy 

 fchift, which feem torn from the beds direftly over the re- 

 fervoir whence the explofion proceeds. Some cryftals and 

 fparkling laminae of pyrites found in thefe fragments, prove 

 that the heat of the refervoir was not fuificiently powerful to 

 afFeft the beds which contained thofe pyrites, nor was the 

 mud difcharged from the gulf more than luke-warm. The 

 appearance of fire, which M. Pallas heard defcribed as 

 accompanying the eruption, was probably inflamed hydrogen 

 gas. He fuppofes that a bed of coal has for ages been on 

 fire under Kercha and Taman, and that the fea at times 

 breaking into the cavities, produces a quantity of lleam, the 

 expanfion of which, and the generation of hydrogen gas, 

 force open a paifage for the mud, and drive it upwards in 

 its afceiit. This opinion we ftiall confider when we treat 

 of the probable caufes of volcanic eruptions in the prefent 

 article. In the Penang Ga/.ette of February lo, 1816, 

 there is an account of a mud volcano of great extent in the 

 ifland of Java, rcfcmbling in all the important particulars 

 thofe defcribed in Sicily and Taman. It is fituated m the 

 plains of Grobogno, N.E. of Solo, near the village of 

 Kuhoo. The mud volcano, if it may be fo called, forms 

 an elevated plain, about two miles in circumference, which 

 may be regarded as the crater. In the centre of this plain 

 very large bubbles of mud rofe, and fwelled up to the height 

 of ten or fifteen feet, which on burfting emitted volumes of 

 dcnfe white fmoke. Thefe large bubbles, of which there 

 were two, continued to rife and burll feven or eight times in 

 a minute, and often threw up two or three tons of mud. 

 The fmoke had the fmcU of fulphuretted hydrogen, or, as it 

 it defcribed, like the wafliing of a gun-barrel. As the bub- 

 bles burft, they tlircw out the mud round the centre with a 

 noifc occafioned by the falling of the mud on the plain, com- 

 pofed of the fame mud. Smaller bubbles rofe from fome 

 parts of the plain : from other parts round the large bub- 

 bles fmall quantities of fand were occafionally (hot up to the- 

 height of twenty or thirty feet, unaccompanied with fmoke. 



Vol.. XXXVII. 



This was in parts where the mud was of too ftiff a con- 

 fiftency to rife in bubbles. The mud in every part felt 

 cold. The water which drains from the mud is coUefted 

 by the Javanefe, and expofed to the fun in the hollows of 

 fplit bamboos, where it depofits common fait in cryftals. 

 This fait is referved exclufively for the ufc of the emperor. 

 In wet weather the brine is lefs ftrong than when the wea- 

 ther is dry. The phenon^na attending all mud eruptions 

 arc very fimilar ; in all of them, the muriate of foda ^com- 

 mon fait ) is either produced, or is itfelf an agent in pro- 

 ducing the fermentation which is the immq^iate caufe of the 

 eruption. Though the great volcanoes in America fome- 

 times throw out water and mud, as before noticed, they are 

 properly fire volcanoes, into which water finds accefs. The 

 water is generally hot, and its ejeAion only occafional. 



Pfeudo-Volcanoes The German geologifts have given the 



name of pfeudo or falfe volcanoes to thofe cafual inflamma- 

 tions of beds of coal, that occafionally occur in coal diftrifts, 

 and continue in greater or lefs aftivity for many years. Thefe 

 inflammations are too trifling in extent or intenfity, to be 

 compared with true volcanic eruptions, nor do they prefent 

 the fame phenomena ; for we have never feen a torrent of 

 lava, however fmall, thrown out by any of thefe pfeudo- 

 volcanoes. 



Beds of coal of confiderable extent have been burning for 

 many years near Bilfton, in StafFordfhire. 



By the continued aftion of fire on the ftrata of clay and 

 (hale which accompany coal, fome fingular effefts are pro- 

 duced, the clay becomes indurated, approaching to the ftate 

 of jafper ; and what is called porcellanous jafper is, in fome 

 initances, formed by thefe fires. 



From fome beds of coal, great quantities of carburetted 

 hydrogen gas are evolved, which, when lighted, will con- 

 tinue to burn for a long time. In fome parts of the world, 

 ftreams of ignited inflammable air are emitted conilantly, or 

 at intervals, which polTefs the property of taking fire fpon- 

 taneoufly on their accefs to atmofpheric air : in all proba- 

 bihty, thefe currents contain phofphuretted hydrogen gas, 

 from which the property is derived. We confider thefe 

 phenomena as diftinft from volcanic fires. 



On the fouth-eaft of Natoha, the mountain Climax, the 

 Chimera of the ancients, fituated near the Mediterranean fea, 

 conftantly emits flames from an aperture on the northern fide. 

 This appearance is unaccompanied by any detonation. It 

 is very ancient, being mentioned in the Periplus of Scylas 

 as continually burning. 



The flames that are obferved to ifTue occafionally during 

 earthquakes, can fcarcely be claiTed with volcanic phe- 

 nomena ; they appear to proceed from the fuddcii difen- 

 gagement of hydrogen gas, combined with pliofphorus, 

 naphtha, and other fubftances, which may difpofe it to ignite 

 fpontaneoufly. During the great earthquakes which defo- 

 lated Thrace, Afia Minor, and Syria, in the fourth and 

 fifth centuries, flames were fcen to burft from the earth 

 over a vaft extent of ground. On the 2fith of January, 

 A.D. 447, fubterranean noifcs were heard from the Black 

 to the Red fea, and the earth was convulfed without inter- 

 miffion for the fpace of fix months ; in many places the 

 air appeared on fire. Towns, large trafts of ground, and 

 mountains, were fwallowcd up in Phrygia. On the JOth of 

 May, A.D. 520, Anlioch waa overturned by a dreadful 

 earthquake, and two hundred and fifty thoufand of its in- 

 habitants were cruftied in the ruins. A raging fire covered 

 the ground on which the town was built, and the diftriA 

 around, fpnadmg over an extent of foity-two miles in 

 diameter, and a fiirfa«e of fourteen hunth-ed fquarc miles. 

 Numerous inftanccs of a fimilar kind are recorded by the 

 3 L hilUirian* 



