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of a deep bluish-grey colour, and a fine grain resembling basalt; it was composed of grains of pyroxine as large as a hemp seed, crystals of amphigine, mica in very brilliant small plates, olivine? in transparent and yellow grains, but rare, and finally of portions of a black pumice as big as nuts and incorporated with the lava.

Volcanic Electricity.-In October of the same year the mountain again became active, and an eruption took place one of the most disastrous that Vesuvius ever gave rise to. After frequent ejections of ashes, &c. from the summit, earthquakes, &c. the lava appeared about mid-day of October 21, 1822, on the border of the crater, and came down in two streams. On the 22nd an enormous column of fire 2000 feet high, rose from the top of the mountain, whilst a rain of hot sand, pumice stones, and lava fell. About 2 o'clock P. M.; the first signs of electricity manifested themselves in that part of the atmosphere situated round the column of sand, which rose from the crater in the form of a pine, and shortly, numberless zig-zag flashes continued without ceasing, to penetrate the cloud of cinders without, however, giving rise to any detonation that could be heard. Towards the evening the thunders commenced just as the volcano took, for a short time, an appearance of repose.

About 8 o'clock our philosophers took the opportunity of the short calm and approached the mountain, just as a fresh and more vigorous eruption took place. Soon the whole heaven. seemed on fire from the immense quantity of ignited matter thrown up into it. Towards the middle of the night the paroxysm of the volcano seemed to have risen to its height, but whilst the operations of the crater became more and more feeble, the play of electricity, which embellished the elevated region of the clouds of sand, became stronger aud acquired fresh vigour. At this moment the heavens presented a very unexpected scene, zig-zag flashes of lightning passed in such quantity either from the borders of the clouds of sands into the air, or from one cloud to another, that the edges appeared as

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if surrounded by a fringe of light. A faint idea of the pheno menon may be given by supposing an electric disc continually throwing off from its edge a multitude of flashes of light. The flashes which were so abundant on the edges of the clouds were very rarely seen in the interior, and never formed in their centres, or on the summit of the mountain,

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On the 23d, a horrible explosion threw into the air such an immense quantity of sand, &c. as to threaten the greatest disasters to the towns to which the cloud was carried. The inhabitants of Torre Anunziata, Bosco-trecase, and Ottajano, ran the most imminent dangers; the frequent heavings of the earth, the constant rain of fiery stones, the continual discharge of the lightning, which fell with awful thunder on the most elevated points of the churches, houses, and trees, the number'less flashes which serpentining on all sides, and which not coming less frequently from the earth than from the heavens, traversed even the very roads, produced frightful sensations in those who were thus surprised; and then the lava came 'down upon them. To leave their houses was impossible because of the falling sand and stones, and the lightning; not only the rain of fire covered the ground with stones,. but large globes of fire passed through the air, which burst with dreadful noise, destroying the houses. During this night the sand fell in the streets to the depth of a foot, and its weight on the 1. roofs of the houses and churches was such as with the shaking of the earthquakes to crush them to the ground.

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MM. Montecelli and Covelli found that the sand which fell on the 23d and following days was electrified vitriously or positively. A glass disc strongly excited by the dry skin of a cat, would not retain the grains which fell, whilst a stick of wax excited by the same skin became abundantly charged with them. These falls of sand were accompanied at Resina and even at Naples by a strong odour of muriatic acid and muriate of iron.

Eruption of Vesuvius, October, 1822.-M. Montecelli had

remarked that the eruptions of Vesuvius consisted of a successive series of more and less active intervals, something similar to the paroxysms of some diseases. The following table and remarks illustrate the duration and nature of these intervals with regard to the eruption in October.

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Effects 1. Much smoke, small streams of lava not passing the foot of the great volcanic cone.

2. Rupture of the eastern lip of the crater; column of fire; ejection of lava on the east and west of the crater; small shower of coarse sand.

3. Pine of sand; new jet of lava; small shower of coarse sand.

4. Force of the eruption at its maximum; new explosion with the destruction of the S. E. eminence of the crater; great overflowing of lava from the same side; ignition of the crater; many columns of ignited stones thrown with force into the air; great development of electricity in the clouds of sand.

5. Great eruption of sand; further overflowing of lava; elec. tricity weaker than before.

6. Two pines on the crater; rain of fine red sand.

7. Pine small; small shower of red sand.

On comparing the duration of the paroxysms, it will be seen that the shortest are found in the middle, and the longest at the extremities; but the shortest were the most violent, and the force of the others was inversely as their duration.-Brande's Journal, Oct. 1823.

On the Liquifaction of Gases.-Mr. Faraday, of the Royal Institution, has made some important and successful ex periments on this subject. He first succeeded in condensing chlorine into a liquid. A portion of the solid and dried hy drate of chlorine was put into a small bent tube, and hermeti cally sealed; it was then heated to about 100° F. and a yellow vapour formed which condensed into a deep yellow liquid hea vier than water. Upon relieving the pressure by breaking the tube, the condensed chlorine instantly assumed its usual state of gas or vapour. He found also that, when perfectly dry chlorine is condensed into a tube by means of a syringe, a por tion of it assumes the liquid form under a pressure equal to that of four or five atmospheres.

Mr. F. next succeeded in liquifying muriatic acid gas. He put some muriate of ammonia and sulphuric acid into the op posite ends of a bent glass tube, which he sealed hermetically, and then suffered the acid to run upon the salt; muriatic acid was generated under such pressure as caused it to assume the liquid form; it was of an orange colour, lighter than sulphuric acid, and instantly assumed the gaseous state when the pres sure was removed. By pursuing the same mode of experiment. ing, sulphuretted hydrogen, sulphurous acid, carbonic acid, cyanogen, euchlorine, and nitrous oxide, have also been found to assume the liquid form under pressure.

Mr. Perkins, during his researches upon high-pressure steam seems to have ascertained that atmospheric air is liquified under a pressure of about 1100 atmospheres. He says, that, the air upon compression disappeared, and in its place was a small quantity of a fluid, which remained so when the pres sure was removed, had little or no taste, and did not act on the skin. The experiments evidently require repetition, and may possibly lead to much more important results than those of Mr. Faraday.

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On the Chinese Year.-In the Philosophical Transactions for 1823, part 1st, there is a paper on the Chinese Year, by J. F.

Effects of burning on Limestone or Chalk.

215

Davis, Esq. F. R. S. of which the following notice is given in Brande's Journal for January, 1824.

"One of Mr. Davis's objects in this paper appears to be, to shew the folly of attributing any thing original in astronomical science to the Chinese, who were entirely ignorant of its ob jects and principles, before its introduction into their empire by the Arabians, and afterwards by the European missionaries. On this one subject, says the author, that singular nation has deviated from its established prejudices and maxims against introducing what is foreign,-they have even adopted the errors of European astronomy, for he discovered in a Chinese book, the exact representation of the Ptolemaic system, he adds

indeed it is impossible not to smile at the idea of attributing any science to a people whose learned books are filled with such trumpery as the diagrams of Fo-hi, and a hundred other puerilities of the same kind." Mr. Davis offers several other proofs of the talent which the Chinese possess of stealing the discoveries of other nations and appropriating them to themselves.

The author proceeds to show that the Chinese have no solar year, but that the Chinese year is in fact alunar year, consisting of twelve months of twenty-nine and thirty days alternately, with the triennial intercalation of a thirteenth month to make it correspond more nearly with the sun's course.

Peculiar effects of burning on Limestone or Chalk.—M. Vicat has lately obtained some singular results in the burning of lime. Many years since he observed, whilst burning pure lime with charcoal and coal in a small furnace, that if the fragments of lime on passing through the furnace into the ash-pit, were again put in with fresh fuel, and this many times successively, a lime was obtained incapable of slaking, but which, broken up and made into a paste, had the remarkable character of setting under water.

It is an old opinion among lime burners that limestone which has cooled before it has been completely burnt, cannot by any

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