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from the products of the distillation of animal matter. A very black sediment remained at the bottom of the cucurbite. On applying nitric acid to this mass, no needle-formed crystals were obtained as with the naphtha; the washings of the distilled liquid gave a very viscous reddish mass, which sank to the bottom, instead of the floating yellowish mass obtained with the naphtha.

Not having at my disposal the means and appliances for proceeding to organic analyses, I have been unable to ascertain the composition of the different products to which the reactions above described gave rise: a composition, the knowledge of which is indispensable to a correct appreciation of these products. In publishing this memorandum I have therefore had no other object in view but to point out a few facts relating to the action of bichlorure of sulphur on carbures of hydrogen-facts which have appeared to me worthy to engage the attention of chemists, and susceptible of being connected with one another, and brought under the laws of a common theory.

Deprived of the apparatus and reactives necessary for this study, I have deemed it my duty to give publicity to an entirely novel subject of inquiry, which, in my opinion, holds out a certainty of important discoveries; and I hope and trust that some American chemist, placed in circumstances more favourable, and especially one more skilful, will, by following up this subject of inquiry, ere long enrich the science with several new and interesting combinations.


Cast Iron Battery. In answer to our Arnheim* correspondent's enquiries in a letter, dated March 3rd, respecting the charge of acidulated water for the castiron battery, described in vols. V, and vi, of the Annals, we would say, that no charge of acid liquor will keep it in constant action for two successive hours. The proportions of sulphuric acid to the water, for the best action, would be as 1 to 6, or to 5, but the action suffers a diminution in half an hour, though the battery will keep in good action for more than two hours. With a less proportion of acid, the action is more equable for a longer period; and an occasional renewal of acid liquor will keep it in good action for any required time; this is also the case with all batteries: they must be occasionally fed to keep up their actions.

With respect to the electro-gasometer, we will describe that which we employ in our next number; but we would remark in this place, that the platinum plates for twenty-four pairs of metals, in a double series of twelve, which is the best arrangement, each plate of the decomposing apparatus should not be less than eight inches square : thirty pairs is not a good number for decomposition of acidulated water.-Edit.

• In Holland.

CALOTYPE PAPER. To the Editor of the Annals of Electricity, fic. SIR,-In my note on the preparation of calotype paper, in your last number, page 144, there is a slight mistake, which, as it may have arisen from my mistake in writing, I hasten to correct. It is this : “nitrate of silver to contain 1.20 grs ;" for which read" nitrate of silver to contain 120 grs." The strength of this solution may,

however, be considerably varied, as the proportion of the salt used by Mr. Talbot answers very well for many purposes. I am, Sir, your very obedient servant,

C. J. T.

ELECTRO - MAGNETISM AS A Moving POWER. — The ConsulGeneral of the Netherlands, in a late communication, announces the removal of the obstacle to the practical application of electro-magnetism as a propelling power :" A private gentleman, Mr. Elias, of Haarlem, has just published the description of a new machine invented by him, for the application of electro-magnetism as a substitute for steam. The object of the inventor has been chiefly to remedy the defects which, in 1839, rendered the otherwise ingenious invention of Mr. Jacobi, of St. Petersburg, a total failure, in as far as practical utility is concerned. Those defects originated, it seems, in the erroneous supposition, that the power of the magnetic bars exclusively resides in their extremities—whence the form hitherto given to all electro-magnetic machines ; viz., that of a horse-shoe, -which while it occasions an unavoidable interruption of the magnetic stream at each new inversion of the poles, at the same time leaves the power resident in the remaining part of the bars wholly unemployed. *The new invention of Mr. Elias, on the contrary, has the very great advantage of rendering effective the full power of the magnetic stream uninterruptedly, and throughout the whole body of the apparatus. This consists of two concentric rings of soft iron, standing on the same plane, of which the external one is immoveable, whilst that on the inside revolves round its own axis. By means of a piece of copper wire, wound about each of these rings, he has given them six magnetic poles, placed at equal distances from one another; the whole being so contrived that the one ring exerts its inducing power on the other throughout the whole circumference, and always at the same distance. A small, but very perfect, model of this important invention is now open to public inspection here; and the result of its operation is allowed, by those skilled in such matters, to be such as to ensure the most triumphant success.”Mining Journal.

For an illustration of this force see “ Sixth Memoir," Annals, vol. vi. p. 295.-Edit.

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PHOTOGRAPHY.* M. Arago wished to be heard, in order that he might make known some essential rectifications to the verbal communication which he had made on the preceding Monday, in reference to M. Daguerré. The ioaccuracies committed by the secretary have been in consequence of explanations very little developed which had been given him, on the subject of new photographic processes. It is even to be feared, that the letter of M. Daguerre will not entirely satisfy philosophers, after the lively interest and curiosity which the results announced on Monday last would naturally excite. We will, however hasten to make them known : the facts remain the same as they previously were; the corrections of to-day do not remove any thing which they had appeared to offer of the marvellous, it being of no matter, in effect, whether the instantaneous action produced by the interposition of electricity is produced on this or that substance. M. Arago again adds, in order to excuse himself to those experimenters who since the announcement of Monday have vainly endeavoured to excite by the electrical spark the ioduret of silver ; that neither he nor M. de Humboldt heard the word acidulée, when the ingenious artist imparted his new discoveries to them. We add a copy of M. Daguerré's letter to M. Arago :

"My dear Sir, I have this instant received the Compte Rendu of the session of last Monday, and I perceive that an error has crept into the communication which you have there made of my new method.

“It is in speaking of the iodized plate. Though I do not think that the ioduret of silver is insensible to the electric fluid combined with the action of light, I have not as yet found any magnet, either direct or indirect, capable of forming the image with the vapour of mercury; for otherwise the process will be now as complete as the first, since the face of the plate so prepared is now so sensitive as not to allow time to open and shut the diaphragm before and after the electrical discharge.

* You will doubtless recollect that I spoke to you of a plate acidulée.

" As many persons have, without doubt, already tried to experiment upon my new method, by making use of a plate iodurée, submitted without any intermedial to the vapour of mercury, they will necessarily not have been able to obtain any thing. I trust, then, that you will be willing, as soon as possible, to destroy the word iodurée, which has led them into error. Besides, this communication ought not to be considered but as giving solely the invariable principle of the method.

“I feel so much the necessity of occupying myself in the most active manner possible on these experiments, that I quit all my works in order to give myself entirely up to them.

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