the reception of indigenous ores, which ought to be particularly rich and splendid, continues to be defective, and is eclipsed by many other collections, as well public as private; a circumstance uniformly exciting the surprise of strangers.

"The council earnestly request the attention of members to the grand object of the institution, that, namely, of enlarging our knowledge of the geological structure of Cornwall. It is impossible for a few members to undertake the investigation of the whole county. It is therefore hoped, that, with a view of enabling the society to complete its long-promised, but still very defective geological map, members will, in their respective districts, endeavour to ascertain the nature and relations of the rocks; and transmit their observations made, and specimens collected, from time to time, to the secretary, who will be very ready to assist their inquiries by any advice or information in his power. Any person, even although unacquainted with the principles of goeological science, can, it is obvious, collect specimens of the various rocks in his vicinity; and members are requested to bear this in mind, with the assurance that collections of this kind, with the various localities of the specimens affixed, will very materially promote the important object in view. One grand desideratum, and which might be very easily. supplied by members resident in the different parts of the county, is, to ascertain the exact limits of the different Granite and Killas districts. The farmers and miners, in any part of Cornwall, could give this information to any gentleman that would take the trouble to record it, or to trace the boundary lines in any of the county maps.

Sept. 21, 1819.

By Order,

JOHN FORBES, Secretary."

8. Earthquakes.-Three severe earthquakes took place at Copiapo, on the 3d, 4th, and 11th, of April. The whole city is described as being destroyed by them; and the inhabitants appear to have had time only to save their lives. Copiapo is a sea-port of Chili, and stands on the south side of a river of the same name, about 490 miles N. by E. of Valparaiso,

A severe shock of an earthquake was felt in Trinidad on the 12th of August, at half-past two A.M. A rushing noise, as of wind, was first heard, which was instantly succeeded by an undulatory motion, from east to west, very severe, and lasting four or five seconds. It was a clear moonlight night, and nothing particular appeared in the state of the atmosphere.

A shock, accompanied with a loud explosion, was felt on the 15th of August, at the village of St. Andrews, in Lower Canada.

A dreadful earthquake has occurred in a part of the world in which such phenomena have been extremely rare. The whole district and territory of Kutch, a country situate to the N.W. of Bombay, including several towns and villages, has been destroyed. The entire city of Bhoog, the capital, has become a heap of ruins, under which were buried 2,000 of the inhabitants. This event occurred on the 16th of June. Among the towns that have suffered, are Mandarie, Moondar, Anjar, and Baroda. The earthquake extended northward as far as the city of Ahmedabad, where it did much harm. It was also slightly felt at Poonah,-400 miles from Ahmedabad; and its power extended considerably on each side of the line between those cities. The shocks occurred on several successive days. The first which took place at Baroda, lasted between two and three minutes, without intermission. On the 17th one occurred, on the 18th two, and on the 20th two. The British troops, under the command of Sir W. Keir, were encamped in the midst of this dreadful convulsion, but escaped, fortunately, without much injury.

Three shocks of an earthquake occurred at St. Thomas's, during the hurricane which blew there October the 19th and 20th.

9. Scintillating Limestone.-A peculiar limestone occurs in Vermont, New York, a primitive country. It is of a pale skyblue colour; effervesces strongly with nitric acid, and by burning produces lime. But it gives forth sparks with steel-this was concluded at first to be accidental; but every specimen. tried from various parts of the country, uniformly gives fire

with steel. It is found in layers, blocks, and masses, disseminated among the clay slate that covers the greatest part of the townships in that vicinity. When first taken from the earth, and exposed to the air, it is covered with an incrustation of a dark reddish-brown colour, that crumbles easily between the fingers; and is generally from one inch to a foot in thickness. This incrustation hardens on long exposure to the air. This led to a supposition, that the incrustation was owing to the decomposition of the limestone by sulphuret of iron, intimately disseminated through the rock; which would also account for the singular circumstance of its striking fire. But, on dissolving a portion in nitric acid, and adding a decoction of gall nut, no discoloration was produced.-Silliman's Journal I., p. 241.

10. Native Lead and Cinnabar, in America.-Dr. Conistock, in a letter to Dr. Silliman, gives the following account from M. Stickney of these minerals.'

M. Stickney states, that the situation of Fort Wayne, and the surrounding country, is a high level, probably about 800 feet above the level of the sea. From this place the water-courses divide, and take different directions; on the one hand falling into the gulf of Mexico, and on the other into the bay of St. Lawrence. The whole country is of secondary formation, chiefly calcareous and aluminous.

Bitumen and sulphur are every where to be found, and as usual, accompanied by the metals.

In speaking of the cinnabar, his words are, "I have found a black and garnet-coloured sand, in great abundance, on the shores of the lakes Erie and Michigan; this is a sulphuret of mercury, and yields about 60 per cent. It is so easy to be obtained, and in so convenient a form for distillation, that it must become an important article of commerce."

The native lead was found on the Anglaise river, at a considerable distance from the fort.

Of this he says, "Metallic lead is so interspersed with galena, as to prove incontestibly the existence of native lead."

11. Aurora Borealis.-A very remarkable meteor of this kind

appeared in the evening of October 17th. Seen from Seathwaite, in Borrodale, Cumberland, it formed, about 9 o'clock, an arch extending from east to west nearly, having its higher part inclined towards the south. About 9h. 15', its extremities had moved 12 or 13 degrees northwards, and the whole arch was vertical, being in a plane passing through the magnetic east and west. About 9h. 30', it had retired to its former place and inclination, and afterwards gradually diminished in intensity, until it disappeared. Even small stars were visible through it the whole of the time.-Tilloch. Mag. 54, p. 383.

§ 2. MEDICINE, ANATOMY, &c.

1. New Mercurial Ointment.-Mr. Donovan has lately published, in the Annals of Philosophy, a series of experiments on the compounds of mercury. They relate to the chemical constitution of these compounds, and the proportion of their elements; but are concluded by an examination of the common mercurial ointment, and an account of a new one.

Four troy ounces of mercurial ointment were kept at 212° for some time; they separated into two strata; when cold, the upper stratum, of a light grey colour, was separated; the under stratum was exposed at 212° on blotting paper, which absorbed the remaining lard. The very heavy residue was triturated with a little magnesia, and immediately gave 495 grains of mercury; further trituration with magnesia gave 225 grains more. The earthy mass, treated in different ways, gave a quantity of globules, estimated at 60 grains, and a little oxide appeared. Thus, out of 960 grains, contained by the 4 oz. of ointment originally, 770 grains were collected, leaving 190 grains, the quantity of mercury, apparently oxidized, or 47 to each ounce.

The upper stratum appeared to contain oxide of mercury in chemical combination; and Mr. Donovan believing that the metallic mercury could have no effect on the animal economy, attributed the powers of the ointment to the small quantity of oxide with which the fat is combined. To ascertain if this were the case, this upper part was given to three females requiring the use of mercury. Each rubbed in a drachm every night;

one was affected by the third rubbing, and the fourth put her under ptyalism. Another, after rubbing three times, was so salivated, that she spit two quarts in twenty-four hours, and this, in a less degree, was kept up for ten days. The third was not affected until she rubbed six times, and then not considerably. They were all at length recovered.

Finding the ointment so very active, Mr. Donovan conceived, that by forming a chemical union between fat and oxide of mercury, in very small quantity, the same result might be obtained; lard and black oxide of mercury were, therefore, kept at the temperature of about 350° for two hours, continually stirring them. At the end of the process, it appeared that every ounce of lard had dissolved, and united with twenty-one grains of oxide.

This ointment was tried on many persons, and found to be as active as the common mercurial, containing twelve times the mercury. One drachm could be rubbed in completely, in from six to ten or fifteen minutes, whilst common ointment required thirty or forty minutes, and rarely was any eruption produced. on the part rubbed. The use of it is extremely cleanly, and its expense is very much below that of the common ointment.

For the preparation of this ointment, it is essential that the lard be entirely free from salt, or else calomel will be formed. The oxide may be prepared by decomposing calomel by pure potash, or by pouring solution of nitrate of mercury into caustic alkaline solution.

The fat only dissolves three grains of oxide for each drachm, but the quantity in the ointment may easily be increased. The oxide should be first triturated with a little cold lard, to make the penetration complete.

The degree of heat applied is important. At 212° the oxide and lard will not combine. At 600° the oxide will be decomposed and mercury volatilized. At 500° and 400° the oxide is partially decomposed, some red oxide being formed, and mercury reduced. The best heat is between 300° and 320°; it should be maintained at least an hour, and the ointment should be stirred till cold.