plates, by a similar process; but my experiments are not yet sufficiently mature to present to the public. Those processes which I have disclosed in this memoir, I have no doubt, will be sufficiently appreciated when once known amongst our artizans, some of whom will find them quite as valuable as any silvering or gilding process hitherto patented, and thus monopolised by a sordid few, to the almost total arrest of the progress of these beautiful branches of experimental research.

Royal Victoria Gallery of Practical Science, June, 1842.

EDITORIAL NOTICES.

New Voltaic Battery.

MR. GROVE has formed what he calls a Gaseous Voltaic Battery. It consists of a series of narrow platina plates, previously platinized by voltaic decomposition, from the chloride of that metal.

Each plate is placed in a glass tube, closed at one end and open at the other. The plates are formed into pairs by means of wire, which passes through the closed ends of the tubes. Thus prepared, one of the tubes of each pair is filled with oxygen, and the other with hydrogen, and with the open ends downwards, immersed in a trough containing a solution of sulphuric acid, a portion of which rises up the platinized surfaces by capilliary attraction. The tubes, with their contents, are supported in series, by leaning against wooden supports, at a small angle from the vertical position.

The gaseous contents of the tubes are partly absorbed by the suspended liquor in the platinized surfaces, and consequently give rise to two distinct liquids, one of which is in the hydrogen tube, and the other in the oxygen tube, of each pair. So that the supposed gaseous voltaic battery, appears to be one of the usual kind, consisting of two liquids and one metal.

Mr. Grove gives a list of the usual phenomena, such as a spark, decomposition, shocks, &c., being produced by a series of fifty pairs.

The only remarkable feature in Mr. Grove's statements, are the following:

"

(a) How is its action explicable on the contact theory? I am by no means wedded to any theory, and have constantly endeavoured to look with the eye of a contact theorist upon the facts of voltaic electricity; but I cannot see them in that light. If there be any truth in the contact theory, I either misunderstand it, or my mind is un consciously biased. Where is the contact in this experiment, if not everywhere? Is it at the points of junction of the liquid, gas, and platina? If so, it is there that the chemical action takes place; and as contact is always necessary for chemical action, all chemistry may be referred to contact; or, upon the theory of an universal plenum, all natural phenomena may be referred to it."

This seems to be rather an incomprehensible kind of philosophy!

(b) "Its phenomena present to my mind a resolution of catalysis into voltaic force; in other words, the action of this battery bears the same relation to the phenomena of catalysis as that of the ordinary batteries does to those of ordinary chemistry. Whether these effects could be produced by other inoxidable metals (such as gold or silver), is an experiment worth trying. The more we examine chemical and voltaic actions, the more closely do we assimilate them. For some mysterious reason, three elements seem necessary for very many, if not for all, chemical actions."

Every supposed fact of interest is worthy of enquiry but analogy from previously discovered facts often saves much trouble: and in the present case analogy is sufficient to show that gold or silver will act as decidedly as platina.

(c)" This battery is peculiar in having the current generated by gases, and by synthesis of an equal but opposite kind, at both amode and cathode; it is therefore, theoretically, more perfect than any other form; as the batteries at present known, act by one affinity at the anode, and have to overcome another at the cathode."

There does not appear any thing peculiar in this battery, excepting its form, and the method of preparing the two liquids. All batteries act theoretically.

(d)" "This battery establishes that, gases in combining and acquiring a liquid form, evolve sufficient force to decompose a similar liquid, and cause it to acquire a gaseous form. This is to my mind the most interesting effect of the battery: it exhibits such a beautiful instance of the co-relation of natural forces."

In this paragraph, Professor Grove himself shows, that the gases do not act as gases, but as liquids; and thus disproves the propriety of the appellation Gaseous Voltaic Battery.

Thermography.

WE have repeated some of the experiments of Mr. Hunt with success; in others we have not succeeded in producing the effects stated in Mr. Hunt's paper. We believe, however, that thermography is an appropriate appellation, as the whole phenomena appear to be the production of heat; and have nothing whatever to do with latent light, which of course, must be perfect darkness.

As far as our experiments have been made on the metals, the phenomena appear to be the effects of volatilization and subsequent condensation. If, for instance, a clean shilling be placed on a clean surface of sheet copper, and held over the flame of a spirit lamp, both metals volatilize; the silver vapours, beneath the shilling, condense on the copper, and the copper vapours condense on the shilling, both on its lower and upper side. In some instances inverted images of the letters of the shilling are formed on the copper; and in some others, even the whole of the device of the lower side, produces distinct images, always inverted on the copper. This effect appears to occur in consequence of those parts of the shilling being more

easily volatilized than the other, in consequence of suffering less pressure in the coining process. We are very far from supposing that thermography will not produce still more interesting effects.-[EDIT.]

PROCEEDINGS OF SCIENTIFIC SOCIETIES.
Chemical Society.

THE first part of a paper was read by the president, Professor Graham, "On the Heat of Combinations;" in which the heat evolved in the combination of oil of vitriol with water was examined, and also of the magnesian sulphates with water.-This was followed by a paper by Dr. I. Stenhouse, of Glasgow, "on the Preparation of Pyrogallic Acid:" in which he finds it not to combine with strong bases, and confirms the analysis of that acid made by the late Mr. R. C. Campbell; and a paper by Dr. Fownes, in which he removes the objections advanced lately by M. Reiset, to the usual process for determining the nitrogen of organic compounds in the form of ammonia.

A paper by Alexander R. Arnott, Esq., "On a form of the Voltaic Battery, and the mode of the Chemical Affinity in the Voltaic Circle." Now that the voltaic battery is employed in several manufactures, and its use likely to extend soon to others, the saving of the zinc or positive metal, which is dissolved, is an object of interest. The construction, also, of batteries, in which an intense chemical force is obtained from other sources than metallic oxidation, suggests important theoretical inquiries. M. Becquerel obtained effects, as he supposed, from the combination of acid and alkali, which Mr. Faraday does not reject, although not fully included in his theory of voltaic action. Mr. Arnott finds, that it is only easily deoxidated acids, such as nitric and chromic acids, which thus act with alkalis, and that it is really their oxygen, combining with the bydrogen of water, which produces the current, and not the combination of acid with alkali. The most efficient arrangement of this sort, is ordinary nitric acid, a solution of sulphuret of potassium, separated by porous stoneware, with a plate of platina in each liquid. A single pair will decompose water. The instrument exhibited, consisted of six pairs, each being a cylinder of one inch in diameter, within another of two inches, and both two inches in depth. The inner cylinder was porous, and contained nitric acid, of density 1.35, the outer cylinder contained solution of sulphuret of potassium, of density 114. Circular plates of platina foil, which may be exceedingly thin, were placed in each liquid, and alternately connected. In short, the construction was precisely similar to Mr. Daniell's constant battery, except that both metals were platina, and the fluids of course different. The battery described, decomposed water to the extent of half a cubic inch of mixed gases per minute, for two or three hours. Deoxidation proceeds rapidly in the nitric acid, in which deutoxide of nitrogen appears, while a corresponding oxi

dation occurs in the sulphuret of potassium, or the oxygen of the former is carried, by a chain of voltaic decompositions, to the latter. Hence, the conditions of activity in such a battery are, attraction for oxygen in one liquid (as in sulphuret of potassium), and the power to supply oxygen readily by decomposition in the other liquid (as in nitric acid). The more highly the two liquids possess these opposite properties, the more intense the action of the battery. The limit of this action was also shown to be the point at which the oxidating actions of the two liquids are equalised. Thus, when the liquids in the two cells, and in contact, are per-sulphate and protosulphate of iron, on connecting together the platina plate from each, oxygen continues to proceed from the first to the last, till the proportion of per and proto-sulphate of iron comes to be the same in both vessels.

Electrical Society.

A letter from Mr. Weekes was read, accompanied by some specimens of acari, developed in the highly poisonous solution of yellow ferro-cyanuret of potass. Three notices from Mr. Lettsom were read: 1st, "Of a new and important application of Galvanism," by Prof. Jacobi; in which it is stated, that he succeeds in extracting gold from its ores by the galvanoplastic art, and that he presented the King of Prussia with a plate of pure gold thus obtained, weighinglb. troy. He extracts silver in a state of aggregation. 2nd. A note "On the employment of Electro-Magnetism in the movement of Machinery.' The German diet, some years ago, promised M. Wagner 100,000 florins, if his apparatus for this purpose should eventually be found to answer. In July last, he made an official report to the senate of Frankfort, in which he states that every difficulty is at length surmounted. 3rd." On M. Peclet's new Conden

"

M. Peclet's experiments place the metals in electrical order, thus zinc, lead, tin, bismuth, antimony, iron, silver, platina, gold. A paper" on the Polarity of the Battery," by J. P. Gassiot, Esq., was then read. Anomalous results have appeared on this subject, and the aid of a water battery, which, by analogy, would be inferred positive, has been described as negative, and such was the result obtained by Mr. Gassiot on a hurried test; but on closer investigation, he found the result to be due to an injudicious method of applying the test, viz., the excited rod to the electroscope. If the rod is applied to the side of the instrument, one result obtains; if to the top, the converse appears. By a series of diagrams the author explained the apparent contradiction, and demonstrated that the end we have esteemed positive in other batteries, is so in the water battery. And he here takes occasion to disapprove of the employment of any other than the old and well recognised names for expressing these characters; he insists, that so long as we use positive and negative for the machine, we can use them safely, and should use them, for the battery. Mr. Walker then read his trans

lation, in abstract, of M. Becquerel's paper "On the Electro-Chemical Properties of Gold." This portion solves the question of extracting ore out of many metals in solution, and treats on gilding.

Paris Academy of Sciences.

Some conversation took place respecting the discovery of M. Moser, as communicated to the academy by M. Humboldt, respecting the transmission of an image to a highly polished plate of metal without the aid of light, and at the same time, without the two objects coming into direct contact. Our readers will remember the announcement that the image of an object suspended in a box from which light was excluded, was indelibly fixed upon a plate of polished copper which did not touch the object in question. It was assumed that this phenomenon was produced by the rays of heat, which, although not sensible to the observer, are always present, and that a slight difference in the temperature of two bodies, the one active and the other passive, will suffice to operate this wonderful result. We now learn that M. Moser has applied his process to the transfer of a print after Raphael to a plate of copper. During nine days the print was suspended in perfect darkness at the distance of the twentieth part of an inch from the polished surface of the copper, and at the end of that time, the whole of the print was visible on the metal. The same influence was felt on a plate of glass after a process of only two days. The same result may be obtained from an engraved copper plate upon a polished plate of any metal; but, in this case, the two objects must be placed as near as possible to each other without touching, and nine days are requisite for the operation. The transfer of a subject from paper upon polished glass is said to be a process of great facility. M. Moser, however, states that the image thus received upon glass is of an exceedingly white colour, and is easily effaced by rubbing.

PRIZE VOLUMES FOR THE FIRST HALF YEAR OF 1843.

1st. For the paper descriptive of a more powerful and economical voltaic battery, than any at present known. The test, to be decomposition of acidulated water, with the terminal metals at one inch asunder.

2nd. For another voltaic battery: conditions as before. Test, the decomposition of pure water, with terminals four inches asunder.

3rd. For a thermo-electric battery, superior to any now known, differently constructed, and more economical. Test, the ignition of the greatest length of platina wire, of of an inch diameter.

4th. For any magnet that will suspend one hundred weight, with the cross-piece at the distance of one inch from the poles.