er? I have experienced in this place, as I have stated, three ruinous earthquakes, that of 1822, which I passed in the house until the back fell, that of 1829, and the present; and from observations on each occasion and now again, particularly as in each case I have been calm and resigned, I think I may be allowed to venture my conjecture in common with others, in which I feel so confident that you are at liberty to submit them to your scientific friends if you please, and if any require further particulars I shall be happy to give them. I may, however, add something more ;-the barometer and thermometer indicated nothing, nor was there the least warning of any description; but as invariably occurs after a heavy shock, we had on the third day after a shower of twelve hours' rain, for which I had already prepared, aware of its being the consequence, happen at whatever season it may. I conceive, also, that I have felt less relaxed than before it. I cannot understand all these things unless electricity be the agent; while the atmosphere must be affected in some way to shower down rain at seasons when under ordinary circumstances it does not fall. Santiago (the capital of Chile), Casa Blanca, and Quillota seem to have suffered equally with Valparaiso; and the latter two places worse, while some of the public buildings of the capital are ordered to be pulled down. My wife, who is at that place, mentions every subsequent shock tally. ing exactly with those here. The shock of 1822 was, however, about double in force and time; and I recollect well it was with difficulty I could stand,-whereas on the present occasion I had no trouble. On that occasion, the sea in the Bay of Valparaiso retired considerably, and was several days in reaching its former level,-while on this no such thing was observed. Your newspapers may make out a different story, but you have here at least correct observations. The country is advancing fast; but it is an awful fact to contemplate that the most massive buildings of the country are the first to yield to the phenomena referred to."

The generally received impression is, that earthquakes have their origin in consequence of violent subterranean action, doubtless of a chemical character. Sometimes the violent eruptions of volcanoes are accompanied by severe earthquakes; and in regard to those of Peru I will instance one of this species, in which volcanic action was accom. panied by a terrific earthquake, viz., the eruption in February, 1600, in the mountain range of Ornate, twenty-two leagues from Arequipa. On the 15th of that month the volcano broke out with great fury and the ground was in continual motion. On the 18th, in the evening the movements were more rapid, and at 10 P. M. there was such a shock that it awoke the soundest sleepers, and every five minutes during the night shocks continued. On the morning of the 19th occurred a dreadful shock, of which the Spanish MS. from which I extract this says, the movements were now more rapid, and in the twenty-four hours there were more than 200 shocks. The heavens were darkened with clouds of eruptive matter, flashes of lightning were seen, and then there descended much white ashes like a fall of snow, which covered the country around.' On the 28th of the same month happened the most dreadful shock of all. The town of Quinistacas, four or five miles distant from the volcano, with 100 inhabitants, was buried; the town of Ornate

also perished; also many villages in the vicinity were ruined; indeed, the whole country was desolated and ashes fell more than ninety miles distant from the volcano.

P. M.

The first earthquake I experienced was in 1825 and at Chile. There was a shaking of the ground, some houses and walls fell down, and the water in the (arequias or) water-courses splashed over. I was also in that of 1829, being in Santiago. The commotion commenced on Sat urday the 26th of September, at twenty minutes past 2 P. M. The prin cipal undulations appeared to come from the southeast. The great shock was one and a half minutes' duration. Half an hour afterwards there was a shower of rain,—and another slight shower at half-past 4 The weather, however, before the earthquake was rather inclined for rain. During the night of the 26th there were slight shocks; also some on the following days, Sunday and Monday. On Friday the 1st of October, at half-past twelve, there was another shock,-as well as at half-past one. I went out into the street and found the inhabitants look. ing at two volcanoes that had broken out,-one in the Dehsa, behind the first range of the Cordillera,-the other in the mountains of Maipu (which last was observed to be in activity just after the earthquake of the 26th), the smoke rising majestically. In Peru I have felt many,— but not very heavy earthquakes. In the province of Tarapaca, lat. 20° south, I have noticed them as occurring two or three times a month,— sometimes accompanied by a slight rumbling noise, which appeared to be subterraneous. But on one occasion, being in the silver mines of Gu antajaya, a few miles east of the port of Iquique in the province of Tarapaca (these mines are from 2,000 to 3,000 feet above the sea), at about 100 yards perpendicular depth in the mine a slight rumbling noise was heard, as if coming from the Andes, which increased and then passed onwards to the west; the noise was immediately followed by a horizontal undulatory movement, then a vertical, then a mixture of these, or a shake, and then all was quiet, save a commotion occa sioned by some of the loose stones of the mine rolling downwards. My impression then was, and still continues, that earthquakes in the region under discussion (Peru and Chile) originate from volcanic causes. A great part of the Andes is volcanic; Chile abounds in active and quiescent volcanoes; and in the province of Tarapaca there are the volcano of Isluga, with its five craters,-the Volcancitos or Water Volcanoes of Puchuttisa,-doubtless many quiescent ones,-on its northern boundary the volcanic group of Gualtieri,-and on its southern the volcanoes of Laguna, Olea, &c. Still, the account received from my friend, Mr. Budge, appears so very circumstantial, that I am induced to give his information regarding the late earthquake in Chile

in extenso.

SCIENTIFIC

INTELLIGENCE.

I. CHEMISTRY AND PHYSICS.

1. Laws of Magnetism.-TYNDAL has studied the laws which govern the attraction of an electro-magnet upon a spherical mass of soft iron. The apparatus employed, consisted of an electro-magnet in the form of a straight bar 10 inches in length and 1 inches in thickness, and wound with 360 feet of copper wire; this magnet was placed vertically under one extremity of the beam of a balance from which was suspended a sphere of soft iron, in such a manner that when the sphere rested upon the end of the magnet, and the copper suspension wire was tense, the balance beam was exactly horizontal. Weights were placed in a scale pan attached to the opposite end of the beam so as to hold the sphere of iron in perfect equilibrium; in this manner the effect of the weight of the sphere was eliminated. The electro-magnet formed part of a circuit comprising also a galvanic battery, a tangent's compass, and a rheostat. In experimenting, a known weight was placed in the scale pan opposite the sphere, and then by means of the rheostat the force of the current, and consequently the attraction of the magnet, was gradually diminished till the sphere separated from the surface of the magnet; at this instant the angular deflection of the needle of the tangent's compass was noted. In this manner the attractive force corresponding to a given intensity of the current is directly expressed by weight. The principal results obtained by the author in this investigation are as follows:

(1.) The mutual attraction between an electro-magnet and a sphere of soft iron in immediate contact with each other, is directly proportional to the force of the magnet or of the magnetizing current.

(2.) If a constant force be applied to the sphere in a direction opposite to that in which the attraction of the magnet is exerted, the attractive force of the latter must vary inversely as the square roots of the distances in order to hold the sphere in equilibrium when its distance from the magnet varies.

(3) The mutual attraction between a sphere of soft iron and a magnet called into action by a constant current, is inversely as the distance between the sphere and the magnet.

(4.) The mutual attraction between an electro-magnet and a sphere of soft iron, when the two are separated from each other by a determinate distance, is proportional to the square of the induced magnetism. Pogg. Ann., lxxxiii, 1.

2. Magnetism of Oxygen gas.-PLÜCKER has given the results of a comparison of the magnetisin of oxygen with that of iron. A glass globe was filled with oxygen of the same tension as the surrounding air. The amount of attraction exerted by an electro-magnet npon this globe was then determined by means of a very delicate balance. The globe was then emptied and filled with a solution of chlorid of iron, and the magnetic attraction again determined in the same manner. The attraction upon the oxygen was found to be to that on the solution

as 8.0678: 1. To determine the attraction exerted under the same circumstances upon soft iron, a glass vessel was filled with a paste made by grinding pure metallic iron in powder (reduced from the oxyd by hydrogen) with a mixture of fresh lard and wax. The amount of at traction upon this glass vessel when empty was first measured, then the attraction upon the same vessel when filled with the solution of chlo rid of iron, and finally the attraction upon the glass when filled with the paste of iron. The amount of attraction upon the glass vessel when empty, was subtracted from the amount upon the vessel when filled with the solution and with the paste. In this manner the magnet. ism of the solution was found to be to that of the iron as 1 : 230-49; the diamagnetic action upon the lard and wax was found to be so slight that it could be entirely neglected. By combining the two numerical results obtained above, Plücker found the specific magnetism of oxygen to be that of iron as 1:285-7. If we refer the specific magnetism of the two substances to equivalents instead of to equal weights, we find for the equivalent of iron a degree of magnetism 81-8 as great as that for an equivalent of oxygen. By the same method Plücker found for the magnetism of sesquioxyd of iron the number 891, that of iron being taken as 1,000,000.-Pogg. Ann., lxxxiii, 105.

3. Molecular structure of organic bases.-HOFMANN has communi cated to the Royal Society the second series of his researches, on the constitution of the organic bases-researches of which it is impossible to speak without enthusiasm, and which have thrown a flood of light upon this department of organic chemistry. In a former memoir the author demonstrated that the three equivalents of hydrogen in ammo nia are susceptible of being successively replaced by the radicals of the ethyl series (Cn Hn+1) yielding a new series of ammonias repre sented by the general formula

N(X. Y. Z),

in which formula X, Y, and Z, represent either hydrogen or an ethyl radical. The combinations of these new ammonias with acids, may be regarded as ammoniums in which one or more equivalents of hydrogen are replaced by methyl, ethyl, &c. Hofmann now finds that the four equivalents of hydrogen in ammonium are susceptible of replace ment by other radicals, so that the most general formula for a large number of organic bases is

N (W. X. Y. Z).

The author describes in the present memoir eight new ammoniums in all of which the hydrogen is completely replaced by other radicals.

Iodid of ethyl and triethylamine (N(C4 Hs) 3) heated together for a short time in a sealed glass tube, exhibit a powerful reaction, and on cooling solidify into a crystalline mass easily purified by solution in cold water and recrystallization. These crystals are the iodid of tetre thylammonium and are represented by the rational formula N(C4Hs); their formation is expressed by the equation C12 H15 N+C4 H C16 H20 NI; when rapidly heated they fuse and are decomposed into triethylamine and iodid of ethyl, which again unite in the receiv er to form the original compound. The new iodid perfectly withstands the action of a concentrated solution of caustic potash; treated with solutions of the salts of silver, it readily yields iodid of silver and salts

of the oxyd of tetrethylammonium. The oxyd of the new base N(C4 Hs) O is easily obtained by digesting the iodid with oxyd of silver in slight excess and filtering, when a clear and colorless solution of the new oxyd passes the filter. As thus prepared the liquid exhibits the strongest analogy to the caustic alkalies potash and soda, it possesses a pungent bitter taste, when concentrated it acts upon the epidermis which it destroys like caustic potash; like this too, it saponifies fats; converts furfuramide into furfurine; decomposes oxalic ether into oxalic acid and alcohol; expels ammonia from its salts even in the cold, and may be substituted for potash in Trommer's well known test for sugar. In its action upon metallic salts the new oxyd is also exactly analogous to caustic potash; it yields however no amalgam corresponding to the well known butyraceous ammonium compound. When evaporated upon the air-pump over sulphuric acid and lime the oxyd may be obtained dry, and even crystallized in long hair-like needles; the dry mass appears to be the hydrate N(C4 H5) 4 O, HO corresponding to the hydrate of potash KO, HO. A concentrated solution of the oxyd of tetrethylammonium is decomposed by boiling, yielding water, triethylamine and olefiant gas, NC16 H20 Ó, HO≈NC12 H15+C1 H4+2HO. The salts of the new base are mostly very soluble and even deliquescent; the double chlorid of platinum and tetrethylammonium crystallizes in beautiful octahedrons. The other new ammoniums described by Hofmann are, (2.) Methylotriethylammonium, (3.) Amylotriethylammonium, (4.) Methylodiethylamylam

monium,

N. (C4 H5)3. C2 H3.

N. (C4 H5)3. C10 H11.

N. (C4 H5)2. C2 H3 . C10 H11.

(5.) Phenylotriethylammonium, N. (C1 H5)3. C12 Hs.

(6.) Methylethylamylphe

nylammonium,

(7.) Tetramethylammonium,

(8.) Tetramylammonium,

N.C4H5.C2H3.C10 H11.C12 H5.

N. (C2 H3)4.

N. (C10 H11)4.

all of which of course exist only in combination; among the products of their decomposition by heat, the author describes several new ammonias or nitryl bases not hitherto considered. The oxyd of tetramylammonium when decomposed by heat yields triamylamine and a volatile hydro-carbon, doubtless amylene; oxyd of tetramethylammonium is also decomposed by heat, but the products of the decomposition have not yet been thoroughly studied: finally the oxyds of the ammoniums (3), (4) and (5), all yield olefiant gas when boiled in concentrated solutions. By the action of the iodids of methyl and ethyl upon conine, nicotine and leucoline, Hofmann has obtained new organic bases, one of which-leucoline in which an equivalent of hydrogen is replaced by an equivalent of methyl-may possibly prove identical with quinine, C18 H (C2 H3) N+2HÓ=C20 H 12 NO2.

In conclusion the author directs attention to the important theoretical bearings of the new alkaloids. In the first place it is to be observed that the action of the bromids or iodids of the alcohol radicals upon ammonia, give rise to not less than four distinct groups of organic bases; three of these-ammonias-are volatile, the fourth-ammoniums— SECOND SERIES, Vol. XII, No. 36.-Nov., 1851.

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