REMARKS.

a. A very stormy night. About 3 A. M. a sudden violent gust, with hail, after which the wind fell.

b. Hoar frost.

c. c. A little snow. The water in the evaporation-gauge having been frozen, a small quantity of salt was now introduced to prevent its forming a solid mass.

d. Misty A. М.

e. Snow, in considerable quantity, for the season; which was dissolved by rain in the course of the day.

f. A smart shower of hail, followed by heavy rain, A. M.; fair P. M; wind very high the whole day.

g. The earth much hardened by the frost, though the depression of temperature was not considerable. This is to be ascribed to the previous cooling it received from the melted snow.

The Barometer has ranged for the most part below the mean, though the middle of the month is distinguished by a pretty bold curve in elevation. The fore part of the period was almost constantly windy; the latter very cold, with hoar frosts; the greatest depression of temperature being after sun-rise.

Plaistow, 6th of 12th mo. 1807.

L. H.

RESULTS FOR OCTOBER.

Mean Pressure Barom. 29,65-Highest 30,15 -Lowest 28,90 -Range 1,25

Mean Temperature - 53°,85-Highest
Dew-Point

66°-Lowest 42°-Range 24°

Highest 58°-Lowest 41°-Range 17°

Rain this Month, 2,375 Inches. --Total this Year, 26,330 Inches.

Mean Pressure Barom.
Mean Temperature

Dew-Point

RESULTS FOR NOVEMBER.

Wind variable.

29.46.-Highest 30.15-Lowest 28.50.-Range 1.65.

38.20°-Highest 52°. -Lowest 19°-Range 33°.

- Highest 46°. -Lowest 30°-Range 16°.

Rain this month, 4,695 inches. - Total this year, 31,025.

Manchester Lying-in Hospital, Dec. 3, 1807.

THOS. HANSON.

INTELLIGENCE

RELATIVE TO ARTS, MANUFACTURES, &c.

Professor Davy's Discovery of a Metallic Substance in Alkali.

In our last number such particulars were mentioned of Professor Davy's remarkable discovery as could be collected in the short interval between the time we heard of it and that of sending the Athenæum to press. Since that time we have learned the following more exact account of the process by which Mr. Davy effected the reduction of Potash and Soda, as communicated by him to the Royal Society in the Bakerian lecture.

Mr. Davy in the last Bakerian lecture, suggested the probability that other bodies, not then enumerated, might be decomposed, or exhibited in more simple forms, by electricity, particularly that excited by the galvanic apparatus. Since that time by means of several very powerful Galvanic troughs, consisting of 100 pairs of plates six inches square, and 150 pairs four inches square, he has succeeded in decomposing Potash and Soda. This was effected by placing the Alkali moistened on a plate of Platina, and exposing it to the galvanic circle; when Oxigen was disengaged and the primitive base of the Alkali left on the plate, in form and appearance much resembling small globules of Mercury, and of an highly inflammable nature. These globules are lighter than any fluid, as they swim in distilled naphta. The base of Potash is of a specific gravity as six, that of Water being ten. At the freezing point these globules ▸ are hard and brittle, and when broken and examined with a microscope they present a number of facettes with the appearance of crystallization; at 40° of Farenheit they are soft, and can scarcely be distinguished from globules of quicksilver: at 60° they are fluid, and at 100°. Volatile. When exposed to the Atmosphere they rapidly imbibe oxigen, and reassume their alkaline character. In distilled Naphta they may be kept four or five days; but if exposed either to the Atmosphere or to oxigen gas, they almost instantly become incrusted with a coat of regenerated alkali: this incrustation can be removed, and the reduced globule will remain in Naphta, or separated from all contact with oxigen, as before: the Naphta forms a thin film round the globule and excludes the contact of oxigen.

One part of the base of Alkali and two of Mercury, estimated by bulk, (or about 1 part of the base to 48 of mercury by weight,) formed an Amalgam, which when applied in the circle of a Galvanic battery, (which produced an intense heat,) to iron, silver, gold, or platina immediately dissolved these, and converted them into oxides, in which process alkali was regenerated. Glass as well as all metallic bodies was also dissolved by the application of this substance; the base of alkali seizing the oxigen of Manganese, and of Minium, potash was regenerated. One of these globules placed on a piece of ice dissolved it, and burnt with a bright flame giving out an intense heat. Potash was found in the product of the dissolved ice. Nearly the same effects followed when a globule was thrown into water; in both cases a great quantity of Hydrogen Gas was rapidly liberated.

The specific gravity of the base of Soda is as seven, that of water being ten; it is fixed in a temperature of 150°, and fluid 180°.

The specific gravity of the Amalgam was found by means of a mixture of oil of Sassafras with distilled Naphta, in which a a globule globu remained either buoyant at top or quiescent at bottom, in a fluid weighing as nine, water being ten, Mr. Dav Davy tried its effects on the phosphats, phosphurets, and the greater part of the salts of the first and second degree of oxydisement, all which it decomposed, seizing their oxigen, and reassuming its alkaline qualities.

From the medium of a number of analytical, and of nine synthetical expe. riments, it appeared that 100 parts of Potash contain 15 oxigen, and 85 of inflammable base; and that the same quantity of Soda contains 20 Oxigen and 80 base.

Mr. Davy tried a great number of complex experiments on Volatile alkali in which he was assisted by Messrs. Pepys and Allen'; by these he ascertained, that oxigen is also an essential ingredient in Ammonia, 100 parts of it containing 21 of Oxigen: but this result depended too much on eudiometrical calculation to be received as an established fact.

The earths of Barytes and Strontites were likewise examined, as being most analagous to the alkali's, and both yielded considerable quantities of oxigen. Mr. Davy related also some miscellaneous experiments on the muriatic and fluoric acids, which completely refutes the strange opinion held by some, that they did not contain oxigen, as these experiments proved in the most satisfactory manner that oxigen is one of their constituent principles.

Mr. Davy concluded his lecture by remarking the impropriety of limiting the term oxigen to a specific character as opposed to that of Alkali; and observed the necessity of improving the nomenclature in consequence of the new facts discovered, and the influence of the metallic base of Alkali on other bodies; and suggested the importance and extent of the new field these facts opened to geology, as likely to lead to numerous discoveries relative to the formation of various stones, strata, and mountains.

One of the facts, above related, seems so contradictory to the rest as almost to induce us to suspect some mistake in the account from which it has been extracted. That the Alkaline metal should, from its great attraction for oxigen, speedily deprive minium and manganese of it, is what was to be expected; but that it should also speedily couvert gold, silver, and platina, into oxides, after immediately dissolving them, in its state of Amalgam with mercury, is very unaccountable and in no wise consistent with the property mentioned.

What is mentioned of Barytes and Strontites, corroborates our conjectures in the former number, relative to the simple earths in general and Barytes in particular.

It appears, however, on farther consideration, that this discovery somewhat militates against the opinion of Berthollet and of the other French chemists, that Lime was the basis of Potash, and Magnesia that of Soda; for if this were so, on the reoxidation of the metallic base of Potash, we should expect to see Lime produced instead of Potash; and Magnesia instead of Soda, on its base being submitted to the same process.

It may, however, be discovered that other gases may be united to metallic bases, as well as oxigen, and that it is the azote which Berthollet declares to be united to the lime in Potash, which occasions the difference stated; and that the azote both facilitates the reduction of the metallic base, and adheres so strongly to it, that it cannot be separated in its transmutations; there is some analogical reason for the above conjecture, from what takes place in the conversion of iron into steel by cementation, wherein carbon, or charcoal in a gazeous state, becomes united to the iron, and forms a metal differing from iron in many respects; and though the carbon can be easily separated from the iron, yet, that the azote should, on the contrary, resist separation from its base, is in no respect against this opinion, as the degrees of adherence, of different substances to each other, is much oftener various than similar.

The discovery opens a vast field in metallurgy, and the improvement of the useful arts; the strong attraction of the metallic base of Alkali for oxigen may assist much in the reduction of refractory semi-metals; and regulus of nickle, manganese, and of other similar substances will, perhaps, be procured in future without the difficulty before experienced.

The minds of all philosophical men will be employed in conjectures of the extent of the field this discovery opens; but it may not be amiss to repress too sanguine hopes on the matter by the recollection of disappointments on former similar occasions. Men of great chemical knowledge, of our acquaintance, are inclined to suppose that not only the substances analogous to the Alkalis are of a metallic nature, but that sulphur, phosphorus, and carbone, are also metallic compounds not saturated with oxigen, and that even hydrogen and azote are metallic substances in a gaseous state; the latter opinion of these VOL. III.

L

in

în particular appears to us rather chimerical, but this may arise from our want of sufficient experience of the nature of these substances.

Among all the good that may be expected from the discovery, directly and indirectly, it is to be regretted that some evil will arise. There can be little doubt that it will again revive alchemical pursuits, and that their seducing nature will again involve many in the calamities they have so often occasioned in old times.

Pall-Mall illuminated by Coal Gas Lights.

The experiment so long announced by Mr. Winsor, (who has publicly exhibited the Coal Gas Lights for a long period) of lighting a street by the same mode in which his theatre was illuminated, has been at length tried in Pall-Mall.

In this street thirteen hollow lamp posts of iron are erected at various distances, of from about twenty-four to thirty paces, from each other, each supporting three glass globes. In every globe three small jets of flame arise from the same number of apertures in a pipe, that communicates with the hollow of the lamp post; and an horizontal pipe laid beneath the pavement, conveys the Coal-Gas to the hollow lamp posts, for the supply of the flame. The whole is very neatly executed, and the disposition of the branches, that support the globes, has an elegant appearance. The light given out is not so great as we expected from the effect of the experiment made last July by another person, in lighting part of Golden Lane and Beech Street by Coal-Gas, mentioned in our eighth number, p. 187, but this was probably caused by the much greater width of Pall-Mall, which would of course require much more light to produce an equal effect. The lamps as yet erected are on the south side of Pall-Mall and extend in one direction from the Coal-Gas Patent Office, nearly opposite the first street leading to St. James's-Square, to the corner facing St. James's

Street.

The extent of the extreme distance which the Gas has been conveyed from the furnace, exceeds that of the Golden-Lane experiment by about 300 feet. This adds very little to what was before ascertained by the Golden-Lane experiment, on this point; but it is to be hoped that ere long it will be fully determined what is the greatest distance to which the Gas can be conveyed from a furnace with good effect, since on this circumstance depends entirely the possibility of profit from the speculation, as before explained in our first volume, p. 187.

There can be no doubt, however, from what has been done already, but that at least the whole of Pall-Mall at both sides might be lighted by the Gas produced by one furnace; but whether this would be a sufficient extent to give any profit, from the reduction of the oil lamps, must be the result of future calculation; which, however, will be rather difficult to make, as from the air of mystery assumed by Mr. Winsor, it will be hard to determine the expence of producing the Coal-Gas necessary, though that of the oil lamps can be easily ascertained. On this subject we see as yet no reason to recede from the opinion given in our second number, and are much inclined to think that the illuminations of Pall-Mall are intended for the same purpose as those made at Paris, after a signal defeat, as facetiously stated in the old farce of Fontainbleau, "namely, to keep the people in the dark."

Implements for destroying Thistles.

In Essex a very useful implement is employed for destroying Thistles, the universal adoption of which, would much benefit the agriculture of this country. It was invented about ten years ago by a farmer in the same county; in a few years after it was adopted by others, from the great advantage it was observed to afford to the inventor; and every year since its use has rapidly encreased, as it became better known.

'The object in view in the construction of the Implement is by the draft of horses as to force an horizontal cutting instrument of iron through the soil, at a short

4

distance beneath the surface, in such a manner as to cut the roots of the thistles completely across; which entirely destroys them, as they are tap rooted plants, and derive little or no nourishments from horizontal roots.

The cutting instrument is about three feet and au half long, is 5 inches broad, and about an inch thick at the back, and sharp at front; it has strong uprights of iron rising from each end of it, which connect it to the frame by which it is drawn, by passing through square perforations formed in it to admit them, in which they are fastened tightly by wedges. This cutter dips forward in an angle of about ten degrees to give it a tendency to sink a little in the soil; the wooden frame, to which it is attached, consists of a straight beam sloping a little upwards from the horizon, to the lower extremity of which two cheeks are bolted that diverge from each other at their ends about four feet and an half'; the holes for receiving the upright stems of the cutter, are made in these cheeks near their lower ends. The upper end of the straight beam rests on an axle, that passes through two light wheels; the pin that connects the beam to the axle is moveable, and a number of vertical holes are made for it along the beam, that by altering its place the angle of inclination of the beam may be changed as required, and the cutter thereby receive the proper dip to enable it to penetrate the soil as it should do. The wheels employed are generally these before used for coaches, which are bought cheap; they are fully strong enough for the purpose intended, as they are not subject to any heavy pressure; the whole cost of the implement by this mode of management does not exceed three guineas.

Two handles extend backward from the cheeks, rising a little upwards at their ends; by which the implement is guided, and the cutter raised out of the ground at the end of each furrow, when it is to be turned about to work in a contrary direction to its former course. A seat for the driver is supported above the cheeks, by four strong stems of wood, which rise from it for this purpose; this he may make use of at all times except when turning round the implement, and his weight serves to force down the cutter.

In Essex the ground is ploughed into narrow ridges of four furrows; the breadth of the implement is calculated to cut beneath one of these ridges at a time; two horses are sufficient to draw it in general, and they are harnessed to draw abreast, so that they may walk in the furrows between the ridges: they with ease draw it through three acres in a day; and on some occasions five acres have been gone over in the same time, when the thistles were not very abundant, or were of a young growth.

This implement effectually extirpates thistles, and all other taprooted plants, and is of great utility in eradicating those weeds also whose roots only extend to the depth of four or five inches. It is thought by some persons of judgment that it might be used to good purpose for cutting down a bean crop, if first prepared by clearing the furrows between the ridges, from the bean stalks, so as to admit the horses to walk along them; and that it would also serve extremely well for cutting peas and for taking up tunips, and rape, intended to be carried to the homestead, or to be cut previous to giving them to sheep.

It may also serve very well for an instrument for pairing the surface of land, preparatory to the operation of burning, in such general use in Devonshire and many other places; but for this purpose the cutter should be made much shorter, or else be divided into two or more separate parts.

The implement might he simplified, by substituting, for the two wheels and axle directed, a single wheel adapted so as to have its distance from the beam encreased or diminished at pleasure, in the manner used very commonly for ploughs; the seat for the driver might also be omitted; it is imagined by some that it would be better to fix the cutter obliquely to the furrow, or to have it bent into an angle so as to form two oblique edges, to be placed with the point forwards, and this idea is probably correct.

Improvement of Ear Trumpets suggested by J. Gough, Esq.

Phil. Jour. No. 79,

Mr. Gough has tried several experiments on ear trumpets, which are very deserving of notice; the first experiments were made with a view to de