MgSi+6H in accordance with this principle, are isomorphous. Thus chrysolite and serpentine may be isomorphous. The composition of the first, Mg3Si, is anhydrous and constant. Serpentine is hydrated and has a varying composition, wherever found, not affording a chemical formula. But examined with reference to M. Scheerer's views, we observe that in all the best analyses of serpentine, the oxygen of the magnesia and of the protoxide of iron, added to one third the oxygen of the water, is equal to that of the silica; and consequently serpentine is a variable mixture of two isomorphous silicates, Mg3Si, and Mg2Si+3H. M. Scheerer has brought forward numerous other examples from among silicates, sulphates, &c.

M. Scheerer has also discovered that oxide of copper may be replaced in an isomorphous manner by two atoms of water.

We may now see clearly why so many hydrated minerals have never given uniform results, even with the most careful analyses.

The memoir of Scheerer will appear in two or three months, in Poggendorff's Annalen at Berlin. The facts here briefly stated were communicated by him to the Academy of Sciences at Stockholm, at its last session.

16. Influence of Magnetism on Crystallization; by R. HUNT, (Phil. Mag., Jan. 1846, p. 1.)-It has been supposed by many writers that electric or magnetic currents must have an influence on the position and character of forming crystals. The experiments of Mr. Hunt illustrate and establish this point in an interesting and satisfactory

manner.

A tube containing a concentrated solution of nitrate of silver, was placed against the poles of a permanent horse-shoe magnet, and another tube was set away by itself. Crystallization commenced first in the former, and the crystals started at different angles from the glass where it was in contact with the magnet; none forming above the magnet. In the other tube the crystals had no regular arrangement.

In a second and third experiment, by using for comparison another metal, he shows that the cooling influence of the metal was not the cause of this arrangement of the crystals. The crystals, when both poles of the magnet were placed against a capsule containing the same salt in solution, and a piece of metal not magnetic on the opposite side, formed in the fluid almost wholly adjoining the north pole; only three long crystals appeared opposite the south pole, and these were directed towards those springing from the north pole. The same result was obtained in four repetitions of the experiment.

A steel needle was attached, one, to each pole of a suspended magnet, and the two were made to dip into a solution of nitrate of silver in

a watch glass. The crystallizing pellicle on the surface, exhibited curved lines as represented in fig. 1, which lines it is observed are strikingly similar to those assumed by iron filings sprinkled on a paper which is placed over a magnet.

Wires similarly arranged were dipped into sulphate of iron; crystallization commenced around the north pole, and soon after around the south. The position of the crystals showed an obvious tendency to conform to lines of magnetic direction.

When protronitrate of mercury was exposed to the same action, crystallization began at the north pole, and proceeded rapidly to a line half way between the two wires, one half of the fluid being crystallized and the other remaining fluid. At length a few crystals formed around the south pole wire, taking a direction towards those of the north pole. Fig. 1.

Fig. 2.

Crystallization of nitrate of mercury on a plate of glass over an electro-magnet capable of holding fifty pounds, had the arrangement of lines in figure 2 annexed: and with a small battery of more permanent but less powerful arrangement, the result in figure 3 was obtained.

When a plate of copper was substituted for the glass, and a weak solution of nitrate of silver employed, the curves in figure 4 were produced. Fig. 4.

Fig. 5.

Fig. 6.

A tolerably strong solution of nitrate of silver was put on the copper plate, and this left in contact with the magnet for a night, when the copper was bitten deeply by the acid of the salt of silver, in the oval form in figure 5, the inner part of the oval remaining bright.

Figure 6 illustrates another curious result obtained on a glass plate from a weak solution of nitrate of silver and an equally weak solution of sulphate of iron; in five minutes the silver was precipitated in curves as in figure 4, and shortly two curious curved spaces were formed by

the fine deposit proceeding from one pole towards the opposite, increasing in width and then abruptly ceasing before reaching the other pole.

17. Faraday's View of Luminiferous Ether; (Athenæum, No. 965.) -Prof. Faraday, at the meeting of the Royal Institute in April, remarked that the conclusions of Dr. Lyon Playfair, so like his own, and the consideration of the like velocities of light through space and of electricity through dense matter, induced him to utter a speculation long on his mind, and constantly gaining strength: viz., that perhaps those vibrations by which radiant agencies, such as light, heat, actinic influence, &c., convey their force through space, are not vibrations of an ether, but vibrations of the lines of force, which, in his view, equally connect the most distant masses together, and make the smallest atoms or particles by their properties influential on each other and perceptible

to us.

18. Electrophonic Telegraph.-The journals of St. Petersburgh speak of an electrophonic telegraph, the invention of the Chevalier Lasckott, which Prof. Jacob has presented to the Imperial Academy of that city. It is composed of a clavier of ten keys, ten bells of different sizes, and ten conducting wires; through whose means the letters of the alphabet and the words which they form are expressed by sounds and harmonies.

II. MINERALOGY AND GEOLOGY.

1. Ores and Minerals of Lake Superior; by C. T. JACKSON, (Bost. Nat. Hist. Soc. Proceed., March, 1846.)-In connection with many valuable details respecting the mines of Lake Superior, Dr. Jackson states several facts of mineralogical interest. Some of the large masses of pure copper obtained, are stated to be covered with crystals of copper of octahedral and dodecahedral forms. On exploring the chrysocolla deposit at Copper Harbor, a remarkable vein of black oxyd of copper, with black and brown silicates, was discovered. The vein is from eight inches to a foot wide where the black oxyd is obtained, but is very irregular. Dr. Jackson suggests that the chrysocolla, or hydrous silicate of copper, was originally a gelatinous mass, like silica, and that it was deposited on the cooling of the rock; while in the more heated interior the black and brown anhydrous silicates were deposited. He also suggests that the black oxyd might have been precipitated from the hot siliceous solution by the action of hot lime water, which was evidently abundant, and adds that this operation may be easily imitated in the laboratory of the chemist. Trap rocks occur near the vein, and to them the heat is attributed; and the alkalies which produce the analcime in place of laumonite, may have originated from the subjacent igneous rock. Laumonite also occurs in this and in an adjacent calca

reous spar vein, and is doubtless derived from the lime of the spar and the siliceous and aluminous ingredients of the conglomerate and sandstone. Datholite and prehnite in many of the veins contain points of metallic copper; and this fact is supposed to prove a rapid production of these minerals, instead of slow infiltration, on the ground that if it had been slow, the copper would have been oxydated.

2. Damourite in the United States; by E. TESCHEMACHER, (Bost. Nat. Hist. Proceedings, p. 107, March, 1846.)-Damourite, according to Mr. Teschemacher, occurs among the minerals of Chesterfield, Mass., and also with the kyanite of Leiperville, Penn. It is met with as a yellow amorphous incrustation. It gives off water before the blowpipe, becomes milk-white, and melts in the strongest heat at the edges to a white enamel.

3. Diamonds in North Carolina.-We have seen a beautiful diamond of fine water, weighing about four grains, taken from a gold washing in Rutherford county, N. C., and understand that others have been found in the same state.

4. Martinsite, a new Mineral; by M. KARSTEN, (L'Institut, No. 638, March 25, p. 101.)-The name Martinsite, in honor of Capt. Martin of Halle, has been given to a saline mineral from the salines of Stassfurth, composed essentially of 9.02 parts of sulphate of magnesia, and 90-98 of chloride of sodium. This corresponds to 10 parts by weight of common salt to 1 of sulphate of magnesia.

5. Transparent Anadalusites from Brazil; by M. HAIDINGER, (Bull. Soc. Geol. de Franu, 2d ser., i, 20.)-These crystals are green when viewed perpendicular to the faces, and hyacinth-red viewed parallel with the line which unites the longer basal edges.

6. Diamonds of the Ural; (Murchison's Russia.)-Mr. Murchison states that he saw upwards of forty specimens of diamonds, in the cabinet of Prince Butera, which were detected in the detritus upon the banks of the Adolfski rivulet, when the alluvium was there worked for gold. The workings for gold having been discontinued in this place, no more diamonds have been found. Baron Humboldt, before his visit to Siberia, had foretold that diamonds would be found in the Ural, as they had in other countries which contain platinum and palladium; while he was there the discovery at Chrestovodsvisgensk was made, and since then they have been found at three other places in the Ural chain. A quartzose micaceous shist, identical with the itacolumite of the Brazils, occurs in a portion of the chain adjacent to those mines where the diamonds have been found, as well as in other parts of the Ural. A Brazilian specimen of itacolumite in the Imperial museum of the school of mines contains two diamonds. M. Claussen says that in the province of Mina's Geraes, (Brazil,) powerful and slightly inclined beds of soft

micaceous sandstone having the aspect of itacolumite, repose directly on transition rocks, and contain diamonds between the flakes of mica, just as garnets occur in mica shist.* Mr. Murchison concludes that these precious stones were originally formed in different parts of the world, in secondary deposits not more ancient than those which constitute the flanks of the Ural chain.

7. Minerals of the Miask; (Murchison's Russia, 437.)-Mr. Murchison informs us that the rich mineralogical treasures from the Miask region in the Urals, and described by M. G. Rose in his work on the Uralian minerals, are all found either in beds, veins, or nests of the granitic ridge of the Ilmen. Some of these are, zircon, black mica in large plates, green feldspar in enormous crystals, albite, elæolite, sodalite, cancrinite, apatite, ilmenite, pyrochlore, monazite, hornblende, beryl, topaz, garnet, &c. Masses of the rock with which some of the above minerals were associated, and which dip south-west from the sides of the greater Ilmen, and appeared to be nothing more than flag-like stratified granite, forming the external coating of the hill, have, under the critical examination of M. Rose, been distinguished by the new name of "Miascite"- —a rock in which in addition to white feldspar and black mica, the place of quartz is taken by elælite. All these rocks are considered as of plutonic origin. On the eastern flank of the Uraltaw, chromate of iron is abundantly found, not less than 20,000 poodst being transported annually to Moscow from one spot, dependent on the Polakofsk Zavod. There, as elsewhere, its associates are serpentine and magnetic iron.

8. Huge mass of green Malachite; (Ib.)-At the copper ground of Nijny Tagilsk, at the chief Zavod of the Demidoff family, a mass of green carbonate of copper has lately been disclosed, of unparalleled size. It occurs at a depth of 280 feet, and its base had not been found at the time of Mr. Murchison's visit, only a part of its summit and sides had been cleared from the matrix. The summit alone has a width of about 9 feet and a length of about 18 feet, an enormous botryoidal mass being exposed beneath. The whole of the surface which had been exposed, was calculated to contain upwards of half a million pounds of pure and solid malachite.

9. Gold and Platina of the Ural and Siberia; (Mr. Murchison's Russia and the Ural.)-The available deposits of the precious metals in Russia are all of them diluvial sands and coarse gravel, and these are found only on the eastern slope, or Asiatic flank of the Ural mountains, and the comparatively level portions of eastern Siberia. The geological

* Bulletin de l'Acad. de Bruxelles, 1841, tome viii, p. 330.

A pood is about 36 lbs. English.