Rough cast iron may, by these means, be made to assume a very beautiful appearance; and articles thus coated will be preserved from oxyda. tion in the interior of habitations. With regard to those intended for the open air, they must be covered with a suitable varnish, in order to protect them. This process is recommended by M. Becquerel.

it

11. New Property of Coke; by JAMES NASMYTH, (Mining Journal, July 29, 1848.)-Having just read in your Journal of the 22d, some observations on the important experiments of M. Jacquelain, in reference to the conversion of diamond into coke, it occurs to me, that may be interesting to some of your readers to be made aware of a discovery in close connection with this subject, which I made several years ago, and which Professor Faraday has done me the honor to communicate to the Royal Institution. The grand distinction between the discovery of M. Jacquelain and mine is simply this, that while he discovers that diamond can be made into coke, I had long since discovered that coke was diamond; in as far as that coke is possessed of one of the most useful and remarkable properties of diamond in respect to its power of cutting glass, owing, doubtless, to the extreme hardness of its ultimate particles, or minute crystals of which a mass of coke is formed. We are apt to consider coke as a soft substance, because we can crush it, and pulverize it with facility; but if we examine into the actual hardness of the minute, plate-formed, crystals, which compose a mass of that substance, we shall find that they are possessed of a most remarkable degree of hardness, and can cut glass with that clean looking cut which is so peculiar to the diamond. I use the term cut with all due consideration, in contra-distinction to the scratching property which is possessed by all substances harder than glass; but it will be found that coke does not scratch, but really and truly cuts the glass, which any of our readers may prove, by taking a small fragment of coke, and switching it at random, across and across, a pane of glass while the sun is shining through it, which will render the beautifully clear, diamond-like cuts more distinct; they will be found to penetrate pretty deep into the body of the glass, and give forth most beautiful prismatic colors, as the light of the sun falls on them. So far this may be all very pretty and interesting, as tending to still further identify the diamond with carbon; but, as I always like to have an eye to practical application of scientific discovery, I am anxious to make these facts known to your readers, so as, together with the following remarks, they may, peradventure, turn this discovery to some useful application; for, although I do not expect to see our glaziers using a cinder to cut the glass for the repair of broken windows, in lieu of a chip of the queen of gems, yet I cannot but feel certain that, when the extreme diamond-like hardness of coke is made known, that the fact will be laid hold of, and turned to good account as a most cheap material for all grinding purposes, such as required for many processes in the arts-to say nothing of its useful application to the sharpening of a razor, as a very superior strop powder, for which purpose, however, the coke must be reduced by levigation to the most minute and impalpable powder. I shall leave the matter of application in the hands of your readers, now that they are made aware of the fact which I have endeavored to communicate to them.

II. MINERALOGY AND GEOLOGY.

1. New Locality of Idocrase, Anorthile? and Molybdenite; by Prof. J. H. WEBSTER, (communicated for this Journal.)-During the past summer I have discovered a new and very interesting locality of idocrase in York County, Maine. It is in the town of Sanford, about four miles north of the Wells railroad station, and about one mile east of Sanford meeting-house.

The idocrase composes a bed, (or vein ?) extending upwards of two hundred feet in a direction north and south, projecting in several places a few feet above the soil. At one extremity it is bounded by granite, and at the other by trap. The thickness of this bed, or vein, could not be determined. The entire mass is idocrase in more or less per fect crystals, crossing one another and interlacing, or projecting into cavities. These cavities are here and there partially filled with white carbonate of lime and a few crystals of what will probably prove to be anorthite, with albite.

Since this discovery, further exploration has brought to light more perfect and brilliant crystals in white quartz, in the same field, at a distance of a few rods.

By the action of an acid, the carbonate of lime has been removed from several masses, and the crystals of idocrase uncovered present brilliant planes, and stand out in bold relief. The crystals are often finely terminated, and present the usual modifications of form; they vary in size from a tenth of an inch in diameter, to an inch and a half; part of one crystal that was unfortunately broken, is now two and a half inches in diameter, and four and a half in length.

Here and there I found molybdenum and epidote in the masses. I have revisited the well known locality of beryls at Royalston, and after ten days labor with three men drilling and blasting, and removing some tons of the granite, obtained but half a dozen broken crystals. The old workings were thoroughly cleared out, and the termination of the original vein that afforded so many fine beryls, was arrived at. This spot I think may now be said to be exhausted.

During these operations, I found four crystals of feldspar of enormous size and beautifully perfect; one was found projecting from the granite twenty-three inches, and its diameter was eleven and a half inches. This was unfortunately broken in the attempt to disengage it; the ter minal portion of ten inches in length, was however removed nearly perfect.

Cambridge, September, 1848.

2. Lapis Lazuli and Mica.-Both of these minerals are found near Lake Baikal, especially in the river Hindianka and all the rivers flow. ing from Mt. Khamardaban. The lapis lazuli is obtained in fragments from the valleys, and according to the natives, it is found after the heavy rains; but all attempts to discover its original locality has hitherto been unsuccessful. Mica is abundant and is used by the natives for windows in place of glass.

3. Mica originating from Hornblende, (in a letter to Prof. SILLIMAN from T. H. FERGUS, dated Westchester, Pa.)-In an examination of the SECOND SERIES, Vol. VI, No. 18.-Nov., 1848.

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greenstone rocks near Boston, two or three years since, I observed the surface, where long exposed to the weather, to be covered with scales of mica, while the interior did not contain that mineral, but hornblende instead, I therefore surmised that the change had been wrought by some action of the atmosphere.

I selected specimens from the different portions of the rock and from several others, and on my return home experimented upon them with the blowpipe: I found that every specimen of hornblende, whether from the outside or the interior of syenite or any rock which contained that mineral, when presented to the inner flame, gave the result usually described in the books; but weathered particles of the hornblende, in the outer flame, took a lighter color, and when cold, the slightest blow caused them to separate into gold colored scales which presented every characteristic of mica.

4. Meteoric Iron of Seeläsgen in Brandenburg.-The Annalen der Physik und Chemie, von J. C. Poggendorff, Band Ixxiii, Stuck 2, s. 329, (1848,) contains a brief notice of the discovery of a considerable mass of meteoric iron near the village of Seeläsgen, between Schwiebus and Züllichau in the provinces of Brandenburg. It had remained until lately unobserved beneath a heap of stones before the house of a farmer. It has an irregular roundish figure, with many deep pits or depressions, measures about a foot in diameter, and weighs (apparently) near two hundred pounds. It is black on the outside, though coated in many spots with hydrated oxyd of iron, perfectly compact within, homogeneous, and of a steel-gray color; and resembles so much in these points, as well as in its malleability, the meteoric iron of Braunau (Bohemia), that, in all probability, it possesses the same chemical composition. Prof. Duflos has already detected, in addition to the iron, the presence of phosphorus, nickel and cobalt. It is soon to receive a full and complete analysis.

C. U. S.

5. Carbonate of Copper and Zine; by Prof. A. CONNELL, (Jameson's Jour., vol. xlv, p. 36, July 1848.)-This carbonate from Matlock has a pale green color with a laminated structure and pearly lustre; it is disseminated in small portions through the matrix. Analysis afforded carbonic acid and water 27.5, oxyd of copper 32.5, oxyd of zinc 42·7, magnesia and lime, a trace=102-7. This result may correspond to an atom of dicarbonate of copper and zinc combined with an atom of water or 2(Cu, Zn) O CO2+HO; but the smallness of the quantity prevented the determination of the relative quantities of carbonic acid and water. This mineral seems to be either identical with aurichalcite or nearly allied to it.

6. On the Occurrence of Ores of Mercury in the Coal Formation of Saarbrück; by HERR VON DECHEN, (Geological Journal, No. 14, p. 33.)—In a lecture before the Society of the Lower Rhine, Herr Von Dechen notices this singular fact. These ores are, in general, very rare, and, in this place, occur in the upper division of the carboniferous group in beds belonging to the productive coal formation, or even to a higher part of the series, in which previously they were not known to be found in any part of the earth. In this district they are confined to its eastern portion; Baumholder, in the district of St. Wendel, being the most western point where they have been found, the Kellerberg,

near Weinsheim, the most northern, Nack, near Erbeslüdesheim, the most eastern. They occur in veins in the normal beds of the coal formation, in the melaphyres, the amygdaloids, and the feldspar porphyries; these massive rocks lying within the range of the carboniferous strata. They are also found disseminated and in fissures in beds of sandstone of this formation, as at Münster-Appel and Waldgrehweiler, wholly unconnected with true veins. The association with the ores of mercury of certain claystones and hornstones, which are not in general found so much developed in this formation, is very remarkable. Within the limits mentioned, ores of mercury have been observed in thirteen different localities, some of which range in straight lines. The longest of these lines reaches from Katzenback, over the Stahlberg, Landsberg, near Obermoschel, to the Kellerberg, and is about fourteen (three German) miles in extent.

7. Notes on the Mines of a portion of the State of Mexico; by Lieut. G. W. RAINES, U.S.N., (from the American Star, city of Mexico.) The general method of mining is probably the same in most of the mines of Mexico; some point is selected in the vicinity of one or more veins, which indicate sufficient richness of ore, and contiguous to fuel and other necessaries, and whose elevation allows the water to be drawn off by subterranean passages, or adits, cut through the adjacent valley to avoid the great expense of drawing it to the surface. The perpendicular shaft is made of sufficient size to accommodate the ropes and bags, by which the ore is raised to the surface, by animals or machinery, and space for the ladders for the descent and ascent of the miners; and also for the pump apparatus, for clearing the mine of the copious streams of water, which, at a considerable depth, pour in from different directions, and the removal of which, constitutes one of the principal items of expense.

From this shaft, horizontal galleries are excavated in the direction of the vein, of a size large enough for the passage of the miners with ore; when the vein is reached, the rocky gangue containing the metal is blasted off, the fragments are broken up, and being placed in small bags about one foot in diameter, are then taken to the foot of the shaft; here some four or five are placed in a bag of skin, which being attached to the vertical rope, is thus drawn to the surface. When a horizontal gallery, or level, has followed the vein so far as to make the air impure, either a new gallery must be made, or a vertical aperture pierced for a proper circulation of the air; in large mines these ventilating shafts are numerous and expensive.

The ore having arrived at the surface, is carried to the pounding mills, where by the action of vertical beams of wood shod with iron, which are raised and let fall by machinery, it is reduced to powder: the coarser particles being separated by a sieve over which the powder falls, are returned to the mills for further action. The finely divided ore is then removed to a rolling or grinding mill, to reduce it to the finest possible state of division; at the works at Sanches, some four miles from Real del Monte, it is mixed with water and submitted to the rolling action, in a circular trough, of two solid cylinders of stone, similarly to the action of the mortar mill.

At Regla the powdered ore is also placed in a circular stone trough, in the centre of which a vertical shaft turns, with two horizontal arms, whose extremities have each a block of basalt attached by chains, which, in the rotary motion, is dragged round, grinding against the bottom and sides of the trough, and by which action, the wet ore is reduced to its finest state. At this stage of the process there are different methods for extracting the silver, depending on the richness of the ore, its constitution, and the fact that modern improvements are as yet but partially adopted.

First method. The wet powdered ore (or schlich) is mixed intimately with a certain proportion of common salt, (chlorid of sodium,) the amount depending upon the kind of ore, and the quantity of sulphur, &c. with which the silver is mineralized; the mass is then spread out on the floor of a reverberatory furnace, and there kept in a red hot state for about six hours. By this means, a portion of the sulphur is driven off in the form of sulphurous acid gas, whilst the remainder unites with the sodium, and the chlorine with the silver; thus the result is a combined mass of chlorid of silver with sulphuret of sodium. The mass is then mixed with salt and water, and placed in revolving barrels, with pieces of iron and a quantity of mercury-about two hundred weight in fifteen hundred pounds of the mass; at the end of about twenty-four hours, it is found that the chlorine of the chlorid of silver has united with the iron, and the silver thus reduced is with the mercury. This amalgam of silver is then washed free from the other substances, which are either dissolved or carried off by the current; it is then pressed in close canvas bags, which thus remove the superabundant mercury; the semi-solid mass is then moulded in iron triangular forms, and distilled in an iron vessel, which separates the mercury and the silver remains pure.

In this process,-which is employed for the poorer ores,-about four ounces of mercury are lost in obtaining eight ounces of silver; this loss arises principally from the oxydation of the sulphur, &c., which being converted thus into acids combine with the mercury, and the resulting salts are carried off in the washings.

Second method. The wet powdered ore is intimately mixed with common salt and pieces of copper, or the protochlorid or sulphate of copper, and a quantity of mercury; the wet mass is spread out on a floor of boards in the open air, about six or eight inches in thickness, and mules are occasionally driven over it, for the purpose of thoroughly mixing the ingredients as the chemical action proceeds.

In not less than twenty days, the process is completed, when it is found, that by the action of the air and moisture, the sulphur has been oxydized at the expense of both, and the hydrogen of the water uniting with the chlorine of the copper or sodium, has formed hydrochloric acid; and any portions of chlorid of silver, formed in the process, are reduced to the metallic state by the copper. The whole is then well washed, when nothing remains but an amalgam of silver with the pieces of copper.

The foregoing is the principal process for the extraction of the silver at most of the mines of Mexico, though mostly applicable to the poorer ores; the loss of mercury, which is probably much greater than that