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county of Cumberland. The present is not the proper occasion for entering into its history, as it is, properly speaking, a compound,and as such will be hereafter described. It is a well-known substance, and is largely employed in the arts, supplying us both with crucibles and pencils: it is now mentioned from its being almost wholly composed of carbon, and from some late experimenters having succeeded in forming crystals as hard as diamonds, by exposing it to strong fusion. Black lead, which is a very improper name, is, in fact, a carburetjof iron, and contains about 91 parts carbon, and 9 iron. When burnt with dry oxygen gas, moisture was deposited, which shows that, like charcoal, it contains hydrogen. This substance was lately fused by the blow-pipe, and the result was numerous globules of matter having a high vitreous lustre, and considerable beauty. Some of them were of jet black, like the most perfect obsidian; others were brown, yellow, and topaz coloured; others were greyishwhite, like pearls, with the transparency and lustre of porcelain; and others were limpid like flint glass, or, in some cases, like the opal. They were so hard as to scratch flint glass, window glass, and the hard green variety out of which aquafortis bottles are made. Some of the globules were scarcely to be distinguished by the eye from diamonds. We have, therefore, in this experiment on the soft and greasy substance, black lead, as iu Sir Humphrey Davy's experiment before mentioned, on chareoal, a proof of the great chemical similarity between diamonds, plumbago, and charcoal; but we have also in the other experiments and results which have been mentioned, a decisive proof that they are not precisely the same, for both plumbago and charcoal are combined with hydrogen.

TO MAKE RANCID BUTTER
FRESH.
We beg leave to recommend the
following request to the notice of

our readers; and we subjoin at the same time one answer, though we cannot say that this method is an easy one. However, we have no doubt that some of our Correspondents will be able to give our inquiring friend more information.

"The Editor of the Chemist will much oblige a subscriber and sincere well-wisher, if he or any of his Correspondents can point out an easy mode of restoring rancid butter, so as to render it fit for use.

"April 14, 1824."

Melt the butter over a slow fire, or by means of a water-bath, at a heat not exceeding 180° Fahr., and remove the scum as it arises. Continue the operation till all the matter that will subside to the bottom has done so, and the butter is transparent. Then decant it or strain it through a cloth, and cool it in a mixture of pounded ice and salt, or in cold spring water, otherwise it will become lumpy. When cool, it will not have entirely lost its rancidity, but it will be much improved. If afterwards well washed with pure water or with ardent spirits, or, still better, with a small quantity of sweet milk, its taste will be found much, if not wholly corrected.

GALLIC ACID CONVERTED INTO TJLMIN.

Ulmin is a curious substance, exuding from some trees, and resembling gum, in some respects, but is not, like it, sticky and capable of being formed into a paste. Gallic acid is also a vegetable substance, found in the parts of many plants, bat more particularly in nut-galls, from which it is named. Professor Dbbereiner lately found, on dissolving a determinate quantity of gallic acid in ammonia, and placing the solution in contact with oxygen, that it absorbed sufficient to convert all the hydrogen of the gallic acid into water. By this abstraction the gallic acid became converted into ulmin, which, the Professor says, may be represented as a combination of two volumes of gaseous oxide of carbon, and one volume of vapour of water.

ILLUSTRATION OF THE PRINCIPLE OF THE SAFETY LAMP.

Take a single thread of cotton, immerse it in oil, and allow it to burn, by means of a cork float, immediately on the surface of the oil. The flame will be about one-thirtieth of an inch in diameter. Take aline iron wire, about one hundred and an eightieth of an inch in diameter, form it into a ring of a tenth of an inch in diameter, and place it over the flame. Though there is a considerable space between the flame and the ring, if the latter be cold the former will be instantly extinguished; but if it be held above the flame, so as to be slightly heated, it may be passed over the flame without extinguishing it. This depends on the power of the metal to abstract the heat of the flame. Sir H. Davy employed a glass ring of the same diameter and size as the iron ring, which, being a bad conductor of heat, did not extinguish the flame even when cold: but when a thicker glass was employed, and the ring made of a smaller circumference, it acted like the iron wire, and extinguished the flame, unless heated. Again, if a small globe of metal, one-twentieth of an inch in diameter, made by fusing the end of a wire, be brought near the flame of a single thread of cotton, such as above described, it will, when cold, extinguish it at the distance of its own diameter. Let it be heated, and the distance at which it operates will be diminished in proportion. These experiments show that small metallic apertures, which admit both light and air, will extinguish flame; and on this principle Sir H. Davy surrounds the miner's candle with a case of metallic gauze, and the flame is prevented, even when in contact with an inflammable gas, from proceeding beyond the gauze.

BIOGRAPHICAL NOTICE OF BECCHER, AN EMINENT CHEMIST. In the middle of the 17th century, when alchymy, owing to the numerous tricks of the alchymists,

and to the conviction then gaining ground, that to hunt after the philosopher's stone was philosophic folly, was falling into disrepute, there was a danger that the numerous discoveries made by the alchymists, and the facts known to them, should be forgotten or lost to the world for ever. The bad character of the professors had extended itself to every thing connected with them; and rational persons, despising their tricks, were disposed to reject even their knowledge. At that time there arose a man, thoroughly acquainted with all the facts which had been discovered by the alchymists, capable of arranging them, and who, at the same time, knew some of the important purposes to which they might be applied. This man was John Joachim Beccher, who seems to have been of Jewish extraction, and was born at Spiers, in the year 1625. He was first a professor of medicine; then physician to the Elector of Mentz; and afterwards 'lived at the court of Bavaria in the same capacity. Towards the close of his life, he came over to England, and died at London about 1682, it is supposed, in great poverty. This man is considered to have collected, from amidst the rubbish and gems of the alchymists, the materials for the foundation of the present science of chemistry. In a work which he published at Frankfort, in Germany, in the year 1669, entitled, Physica Subterranea, he pointed out the use which might be made of the discoveries of the alchymists, and the proper objects to which the researches of chemists ought to be directed. The publication of his work forms a very important era in the history of chemistry; and chemists having since then pursued the path which he indicated, have brought the science to its present state. Perhaps the world may regret that so little is known of this celebrated chemist; but the fame of Beccher, like that of most of the early improvers of science, rests entirely on the single work which bears his name.

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THE ELECTROPHOROUS OF VOLTA.

{In answer to a Correspondent.) A Correspondent, some time ago, requested to beinformed of the best manner of .making an electrophorous. We are not aware that any other or better method has been discovered than that of the inventor of the instrument, the celebrated Volta. Our Plate represents the form of his electrophorous. A is a circular plate of metal, or piece of wood, covered with tin foil, which has a glass handle, F, screwed into a brass or wooden nut, D. The edge of this plate must be pretty thick, and well smoothed and rounded off. The lower plate, B, consists of a resinous cake, and another metallic plate. The resinous cake is formed by melting together equal parts of shell lac, resin and Venice turpentine; and it may either be poured, when fluid, on the metallic plate, if it be provided with a rira, or it may be poured on a marble slab, from which it can be easily separated, when cold, and applied to the metal. Of the three plates, A is called the upper conductor; B the resinous plate; and C the lower conductor. We presume our Correspondent does not require us to describe the uses of this instrument; and that he knows it is an electrical machine, about 20 sparks from the upper conductor being sufficient to charge a small Leyden phial.

ECONOMICAL PREPARATION OF PURE OXIDE OF NICKEL. Speiss, or impure nickel, is to be reduced to fine powder, and roasted till it gives off no further vapours of arsenic, the heat being at first moderate, to prevent fusion, and then increased. Metallic iron,

in the state of filings or nails, is to be added in a quantity which ought previously to be determined, and the Whore dissolved in boiling nitro-muriatic acid, so much nitric acid being used that no protoxide of iron remain in the solution; evaporate to dryness and re-dissolve in water, when a large quantity of arseniate of iron will be left. Add to the solutions successive portions of carbonate of soda until a greenish precipitate appears, at which time all the arsenic and iron will be separated, and part of the copper; the rest of the copper may be separated by sulphuretted hydrogen, and the clear solution thus obtained, when boiled with subcarbonate of soda, yields the carbonate of nickel.

Thus obtained, the carbonate of nickel contains a little cobalt; to separate the latter, the precipitate, as obtained above, by boiling with sub-carbonate of soda, is to be well washed, and diffused whilst moist in water, and a current of chlorine passed into it until in excess: the excess of chlorine is to be allowed to dissipate, and the solution filtered; it now contains not the smallest trace of cohalt, that remaining as a hydrated peroxide, with a certain portion of nickel in the same state. If in the mixed carbonate of nickel and cobalt, the latter is in excess, the residue, after the action of the chlorine, is pure hydrate of cobalt, and the solution contains the nickel with a small quantity of cobalt.— Ann. de Chim. xxv. 95.

NEW PYROPHORUS; OR^ INSTANTANEOUS FIRELIGHTER. In determining the composition of tartrate of lead, Dr. Friedman Gobel, of Jena, observed that this salt, when heated in a glass tube, formed a fine pyrophorus. When a portion of the deep brown mass is projected from the tube, it instantly . takes fire, and brilliant globules of metallic lead appear on the surface of the substance in ignition. The effect continues much longer than in other pyrophori.

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WATER-SPOUTS.

To the Editor of The Chemist.

Sib,—Among the meteorological phenomena which have long excited the attention and inquiries of philosophers, none seems involved in more darkness and obscurity than that of water-spouts. As your Journal is devoted to scientific subjects, and as this as well as most other meteorological phenomena, fall within the department of Chemistry, and can only be explained by chemical principles, I trust you will allow me to present your readers with a description of these phenomena, and afterwards to offer a few words in explanation.

A full explanation I hold to be impossible, till it is clearly ascertained what are the changes which water undergoes when taken into the atmosphere; how it is disposed of when there; and what occasions it afterwards to form and fall. Your readers, acquainted with meteorology, well know that these are doubtful points, which science has not yet fully investigated. My observations will rather tend to put other persons in the right path of inquiry, than to set the question

at rest. If you think them worthy of insertion in your Journal, you will gratify a constant reader, and an Old Sailor.

Your readers doubtless know, that water-spouts are dark black clouds, of a funnel kind of shape, which descend from above to the sea, and which are supposed to convey water into the atmosphere. The drawing I send represents them as they generally occur. At their first formation, they appear, according to Capt. Maxwell's account, as at A, where the black cloud drops from a level surface into a conical form before the disturbance at the surface of the sea, as shown at D, is observed. The effect produced at D is like that of a smoking furnace. The black conical cloud now continues to descend, as shewn at B, till it almost reaches the surface of the sea, and the smoke-like appearance rises higher and higher, till it forms a union with the cloud, from which the spout appears to be suspended. In this situation it is said to put on its most terrific appearance to the mariners who have the misfortune to be in its neighbourhood. When the spout begins to disperse, it assumes the appearance shown at C. The black cloud generally draws itself up in a ragged form, but leaves a thin transparent tube, C E, which reaches to the water, where the smoke-like commotion still prevails.. At this time there is a curious motion in the upper part of the tube.

Another witness says, it was observable of all of them, but chiefly of the large pillar, thaV.towards the end, it began to appear like a hollow canal, only black in the borders, but white in the middle; and though at first it was altogether black and opaque, yet one could very distinctly perceive the seawaler to jit/ up along the middle of this canal, as smoke does up a chimney, and that with great swiftness and very perceptible motion; and then soon after the spout or canal burst in the middle, and disappeared, by little and little, the boiling up and the pillarlike form of the sea water continuing always the last, even for some considerable time after the spout disappeared, and perhaps till the spout appeared again, or reformed itself, which it commonly did at the same place as before, breaking and forming itself again several times m a quarter of an hour.

Captain Napier thus describes one which he saw, on Sept- 6th, 1814, in lat. 30° 47' N., and long. 62" 40' W.:—" The wind being variable, between N.N.W. and N.N.E., the ship steering S.E., an extraordinary sort of whirlwind was observed to form, about three cables' length from the starboard bow of his Majesty's ship Erne. It carried the water up along with it in a cylindrical form, in diameter, to appearance, like that of a waterbutt, gradually rising in height, increasing in bulk, and advancing in a southerly direction. At the distance of a mile from the ship it continued stationary for several minutes, boiling and foaming at the base, discharging an immense column of water, with a rushing or hissing noise, into the overhanging clouds, turning.itself with a quick spiral motion, constantly bending and straightening, according as it was

affected by the variable wind, which then prevailed from all points of the compass. It next returned to the northward, indirect opposition to the prevailing wind, and right upon the ship's starboard beam, whose course was altered to east, in hopes of letting it pass a-stern. Its approach, however, was so rapid, that we were obliged to resort to the usual expedient of a broadside, for the purpose of averting the danger; when, after firing several shots, and one in particular having passed right through it, it appeared for a minute as if cut horizontally in two parts, the divisions waving to and fro in different directions, as if agitated by oppo-site winds, till they again joined for a time, and at last dissipated in an immense dark cloud or shower of rain. The near edge showered in large heavy drops on the ship's deck, till the cloud was quite exhausted. At the time of firing the gun, its base covered a portion of the surface of the water, equal to half a furlong, or 300 feet in diameter, while the cloud itself extended over bead and all round to a very considerable distance. There was never much wind," Capt. Napier adds; " and the water that fell from the cloud and was caught in the foot of the driver (a sail) was perfectly fresh. Low heavy black clouds were hanging about, occasional drops of rain followed, the mercury in the barometer became considerably more convex, and was followed by a clear atmosphere and hot sultry weather."

(To be continued.)

LECTURES ON CHEMISTRY, AT THE MECHANICS' INSTITUTION.

It was impossible for us in our last Number to do any thing more than merely notice Mr. Phillips's first Lecture; and we were, therefore, obliged to postpone to a better opportunity laying an outline of it before our readers. Mr. Phillips began by bespeaking the attention of his hearers, making an apology for using some terms which might probably be unknown

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