2. "On Volcanic Eruptions in Hawaii during the last sixteen years." By the Rev. T. Coan. From the Foreign Office.

In this letter, addressed to and transmitted by Mr. Consul-General Miller, the Rev. Mr. Coan, who has been the resident Protestant Missionary at Hilo for twenty-one years, and still resides there, described some remarkable volcanic eruptions on the Island of Hawaii (Owhyhee) of which he has been an eye-witness during the last sixteen years: viz. the great eruption of Kilauea in 1840, of Mauna Loa in 1843 and in 1852, of Kilauea in May and June 1855, and lastly of Mauna Loa in August 1855. Mr. Coan added an account of his visit to the summit crater of Mauna Loa in October 1855; and referred to his several subsequent visits to the lava-stream which has threatened Hilo.

3. "On the late Volcanic Eruption of Mauna Loa." By Mr. Consul-General Miller. From the Foreign Office.

In this letter, dated July 30, 1856, Mr. Miller referred to the eruption as being still in a state of activity, and enclosed a Number of the Pacific Commercial Advertiser' in which Mr. Coan's visit to the crater in October 1855 was reported in full; and in which it was stated that nearly an entire year had passed since the eruption commenced in August 1855, and the flow, though diminished, was still intense. Late advices state that the fresh or molten lava is not met with until about three miles above the lowest point it reached in November last, or about eight miles from Hilo. The lava now appears to be spreading more laterally, bursting out through the old crust and flowing off to the right and left. At present there is no danger, nor will there be any unless the discharge should be materially increased.

4. "On the occurrence of an Earthquake at Rhodes." By Mr. Consul Campbell. From the Foreign Office.

This communication referred to the severe shock of earthquake which was felt at the Island of Rhodes on the 12th October at about 3 o'clock A.M. It lasted for nearly two minutes, and was accompanied with great destruction of life and property. Its first motion was vertical, the second horizontal, and the third vertical. The shock was felt also in the adjacent islands of Halki, Scarpantos, Cassos, and Symi; also at Marmarizza on the coast opposite.

5. "Additional Observations on the Geology of Bulgaria." By Captain Spratt, F.G.S. Having again visited the Bulgarian coast, Captain Spratt has been enabled to confirm the observations on the freshwater deposits of the Dobrudja, which were read before the Society in June last.

December 17, 1856.-Col. Portlock, President, in the Chair.
The following communications were read :—

1. "On some Freshwater Deposits in Euboea and Salonika." By Captain T. Spratt, F.G.S.

In former communications to the Society the author had described a series of lacustrine limestone and marls, containing lignite, and overlaid by reddish unfossiliferous loams and gravels, as occurring

in the valleys and on the hill-sides in Southern Euboea, Boeotia, Samos, near Smyrna, and elsewhere in the Grecian Archipelago.

In the present paper Captain Spratt described the occurrence of similar deposits on the northern part of Euboea, on the Locrian coast, and around the Bay of Salonika. In connexion with the similar strata in other localities, in and around the Ægean, formerly described, these apparently lacustrine deposits indicate the existence of a great expanse of fresh water over the Levantine area during some tertiary period, probably continuing, according to Captain Spratt, from the eocene to the pliocene epoch.

2. "On the Analysis of Waters from the Turko-Persian Frontier." By Dr. T. Richardson and E. J. J. Browell, Esq. Communicated by W. K. Loftus, Esq., F.G.S.

This was a report on six samples of water from the Lake of Van, the small Lake of Ardchek situated to the east of the former, and their vicinity, not far south-west of Ararat. They were brought home by Mr. Kennet Loftus. Of these, four specimens (two from the Lake of Van and two from Ardchek) belong to a very limited class of waters, such as are found in Hungary and Egypt, and which are more or less rich in carbonate of soda. A water from an acidulated saline spring two miles south of Bitlis contained but traces of the ordinary saline matter and a large proportion of lime and magnesia. Hence it was inferred that probably this water originally came off a dolomite, and subsequently passing through beds of gypsum, thereby suffered a change in its constituents by a recombination among the acids and bases.

3. "Notice of an ice-carried Boulder at Borgholm." By John Wolley, Esq. Communicated by Sir C. Lyell, V.P.G.S.

This boulder was about 10 feet in length, 7 feet broad, and 6 feet deep, and had been carried by coast-ice from an islet about half a mile distant, under the influence of a storm from the north, which, by locally raising the level of the water, caused the groundice to float with its entangled boulders and to convey them to a distance.

4. "Additional notice of the occurrence of Volcanic Bombs in Australasia." By the Rev. W. B. Clarke, F.G.S.

The author sent a notice last year of the occurrence of volcanic bombs in the gold-bearing alluvium of New South Wales; and in this communication adds Victoria and Tasmania as countries in which these obsidian bombs have been observed in the alluvial drift.

5. "Notice of the occurrence of Metalliferous Ores in Siam." By Messrs. H. J. Moyle and C. B. Hillier. From the Foreign Office. This was a memorandum by Mr. Moyle (in a letter from Mr. Consul Hillier) on the occurrence of copper-veins in grauwacke, and of ores of lead and silver, with magnetic and specular iron-ore, in the hilly districts near the River Chaw-Phya (Meinam) in Siam. A small box of ores, chiefly cupriferous, with a specimen of corundum, accompanied this communication.

XXII. Intelligence and Miscellaneous Articles.

ON THE "ANTRIMOLITE" OF THOMSON.

THE

BY DR. HEDDLE.

HE "Antrimolite" of Thomson, in which that chemist found 4.10 per cent. of potash, I make mesolite, finding soda instead of potash. Of the specimens analysed, the second was procured from Mr. Doran, who supplied Dr. Thomson; for the third I am indebted to the kindness of Mr. Rose ;-these facts are mentioned that there may be no doubt of its being Antrimolite that was examined.

This is evidently mesolite (see Philosophical Magazine for January); Dr. Thomson's analysis, however (after substituting soda for potash), seems to point rather to Faröelite. The third specimen was somewhat contaminated by carbonate of lime, calc-spar being the basement†.

ON THE MAGNETISM AND ELECTRICAL CONDUCTIBILITY OF POTASSIUM AND SODIUM. BY M. LAMY.

It has often been attempted to discover a relation between the atomic weights and volumes of bodies and some of their physical properties, such as their density, crystalline form, boiling-points, specific magnetism, &c. With regard to the latter property, it is generally admitted that the most magnetic metals are those which have the smallest atomic volume, and vice versa.

The author has drawn up a table of the principal metals with their densities, chemical equivalents, and atomic volumes. From this it appears that there are numerous exceptions to the supposed law, and that sodium, and especially potassium, ought to be much more diamagnetic than bismuth itself.

According to Faraday, sodium and potassium are diamagnetic. The author's experiments show that these metals are feebly magnetic. Taking every precaution that the masses experimented on should be free from iron, he always found that at the moment of closing the circuit of Ruhmkorff's electro-magnet there was a considerable repulsion, due to the production of induced currents in the mass affected, followed by a manifest and permanent attraction when the electro-magnet had attained its state of magnetic equilibrium. The attraction took place with a globule of potassium extracted directly by the pile, without the intervention of mercury, from a potash which * Potash traces, and some CO2.

† Errata in last paper. There was a misplacement of figures in the Table at p. 55. The formula for Fargite and Faröelite should be

Fargite (2NaO, CaO), 3SiO3+3(Al2 O3, SiO3)+7HO.
Faröelite (NaO, 2CaO), 2SiO3 +3(Al3 O3, SiO3)+8HO.

was strongly diamagnetic. Under the same circumstances, similar globules of pure copper and silver were repelled by the electro-magnet. Thus potassium and sodium appear to be feebly magnetic. If they were feebly diamagnetic, as Faraday supposes, the relation between the atomic volumes and the specific magnetism would not be confirmed in their case.

Movement of rotation due to magnetic induction in the metals,—sodium, potassium, copper, silver, gold, &c.

At the moment when magnetization commences or ceases, the action of the electro-magnet upon sodium and potassium causes energetic movements of repulsion and attraction, due to the production of induced currents in the mass. A more curious phænomenon, which must also be attributed to magnetic induction, is the rotation which may be given to a mass of these metals by successive interruptions of the circuit of the electro-magnet.

If a globule or cube of sodium, copper, silver, &c. be placed in any part of the magnetic field, except in the vertical plane which divides the polar surfaces into two equal parts, there is always a rotation when the commutator is manœuvred from right to left, and vice versa, so as to close and interrupt the circuit or change its direction. The rotation is not continuous; it is intermittent like the ruptures which produce it. Its direction is always from left to right when the mass is towards the operator whose right-hand moves the commutator, and from right to left when it is behind the median vertical plane of the magnet. A succession of ruptures and closures of the circuit, without the reversal of the current, also causes rotation, but less energetically than when the current is interrupted and reversed at the same time.

By these successive magnetizations and demagnetizations, the large copper tube of Ruhmkorff's apparatus may be made to turn for several minutes, so as to give the suspending thread so much torsion that when all electrical movement ceases, the mass rotates rapidly in the opposite direction.

Electric conductibility of sodium and potassium.

The author has endeavoured to measure the conductibility of sodium and potassium. These metals were either cast into thin sticks in glass tubes of 1 to 2 millims., or made into wires. The method of observation followed by him was nearly the same as that described by Pouillet and Becquerel in their researches into the electrical conductibility of metals. His apparatus allowed a resistance of 1 millim. in a silver wire of 0.237 in diameter to be easily appreciated. From the numbers obtained, sodium would be placed after the best conductors,-silver, copper and gold, and before tin, zinc and iron. Potassium, which is a worse conductor than sodium, still comes before iron. These metals are equally good conductors of heat.-Comptes Rendus, October 6, 1856, p. 693.

ON THE MOVEMENTS OF THE FLOATING CRYSTALS OF SOME ORGANIC ACIDS. BY A. SCHEFCZIK.

Crystals of succinic acid and of benzoic acid prepared in the dry way, when thrown upon the surface of clean water, exhibit pe

culiar movements. In benzoic acid the principal character of the movement is a rotation round a point sometimes lying within, and sometimes without the crystals. In succinic acid this rotation alternates with straight movements taking place by jerks, like the course of the water-spiders on sunny days in summer.

The power with which many bodies sprinkled upon the water (such as semen Lycopodii) are carried along by the moving crystals, is very remarkable, and still more so the circumstance that all motion ceases almost instantly, when one finger of the bare hand is immersed in the water.

If a portion of the water in which the crystals have been brought to a standstill be poured away, their motion commences with renewed force, and lasts, if no further disturbance occurs, until the crystals are dissolved. That this movement is a consequence of solution by the water, and produced directly by the one-sided attack of the solvent upon the crystals, may be concluded à priori; but that the behaviour of these crystals should be so modified by touching the water, that as the solution continues the movement of the cry. stals ceases, deserves a closer consideration.

The behaviour of citric acid enables us to get a better insight into this phænomenon. The movements of these crystals (which are split into the finest possible plates, in order that they may float upon the water) leave behind them upon the surface of the water, visible traces of dissolved citric acid. After touching the water, the movement of the crystal ceases, but its solution continues, but with this difference, that the visible trace of the solution no longer floats upon the surface, but sinks perpendicularly to the bottom. The cause of the cessation of movement must be sought for in some body, which has diffused itself over the surface of the water after contact. This body was ascertained to be an extremely thin stratum of a fatty substance, which had separated from the finger in touching the water and rapidly diffused over the surface.

The diffusion of this substance on the surface of the water goes so far, that a glass or metal rod touched by the naked hand, when immersed in the water either immediately brings the crystals in full motion to a standstill, or so far diminishes their movement, that it can only be compared to the nervous convulsions of a dying animal. This property of extremely fine diffusion upon the surface of water, appears only to be possessed by the fatty oils and their soaps; for light wood-tar oil, for example, even when thrown upon the water in drops, did not stop the movements of the crystals.

For the elucidation of these phænomena, the floating lines of the dissolved citric acid furnish a visible explanation; notwithstanding their greater specific gravity, they swim upon the surface of the water. But if this surface be covered by another body, which by its greater attraction occupies the surface as such, the solution passes over into the lower mass of water, and being specifically heavier, falls to the bottom. In the first case the surface alone was the solvent. The displacement of the dissolved portion by the constant closing in of the solvent, caused the movement of the floating crystals.

In the second case the surface of the water was occupied by the