liquids were boiled in clean glass retorts, and great care was taken to prevent any portion of them from being carried over mechanically in the state of drops. The solutions on which the action of the gases and vapours expelled by boiling was to be determined, were contained in Woulfe's bottles, and, in general, the vapours passed through two or three of these in succession. The tubes of communication between the retort and the first bottle, and between the bottles themselves, were plunged to a sufficient depth in the solutions.

1. The mere vapour of pure distilled water when passed through a transparent solution of nitrate of silver, has the property of communicating to it a discoloration, in proportion as it heats the solution to the temperature of ebullition; and the intensity of this discoloration varies from yellow to dark-brown, according to the concentration of the solution, and to the length of time. during which it has been exposed to the action of the vapour.

2. This discoloration is inconsiderable, so long as the solution of nitrate of silver remains under the boiling point, but it becomes exceedingly striking, the instant ebullition commences. The colour which first appears is yellow, but it rapidly becomes darker. The colour of the solution of nitrate of silver, when sufficiently diluted, has a close resemblance to red wine.

3. In the same manner, the solutions of nitrate of silver in the remaining bottles may be discoloured; because the vapour, after heating the liquid contained in one bottle, passes over into the next, and raises its temperature also to the point of ebullition.

4. This discoloration is caused by a deoxidation of the nitrate of silver, and except that it takes place with much greater rapidity, it is similar in all respects to the effect produced by light. In proof of this we may mention, a. The similarity of the colours with those produced by the action of mere light. b. The complete removal of the colour, and restoration of transparency, by the addition of nitric acid. c. The similar deoxidizing effect of the vapour of water upon other metallic solutions, which are easily deoxidized, either by light, or by some chemical action. d. The disengagement of oxygen gas during the process.

5. The most convincing of all proofs is furnished by a solution of muriate of gold. A solution of this salt so much diluted as scarcely to retain a shade of yellow, when heated to the boiling point by a stream of the vapour of water, acquires a beautiful blue colour, exactly similar to the colour produced in it by tincture of nutgalls, oxalic acid, &c.

6. After the expulsion of the atmospheric air, I collected the gas which was disengaged in a constant stream of minute bubbles, from the boiling-hot solution of nitrate of silver. It proved to contain a considerably greater quantity of oxygen than common air: 100 volumes of it mixed with 100 volumes of nitrous gas, sustained a diminution amounting to 91, whereas common air sustained a diminution of only 80."

7. Of the other solutions whose colour is changed by deoxidation, I examined acetate of silver, which became discoloured, like the nitrate, but more feebly; and muriate of platinum, which underwent no alteration.

8. Sea-water and solutions of common muriate of soda and of muriate of magnesia, when boiled, and when the disengaged vapour is passed through a solution of nitrate of silver, occasion appearances of a more complicated nature. In this case, the metallic solution is decomposed, not merely by aqueous vapour, but by the muriatic acid which is disengaged from the boiling liquid; and a quantity of chloride of silver is formed, which the action of the aqueous vapour subsequently renders violetcoloured, provided it at the same time raises the temperature of the solution of nitrate of silver to the boiling point. Should any portion of the nitrate of silver be left undecomposed, it is deoxidized by the vapour of water, and a yellow or brown colour is developed, which mixes with the violet, and imparts to it various modifications of shade. My original opinion, therefore, that the change of colour is caused by the muriatic acid which distils over along with the water, is confirmed, but at the same time restricted, by this experiment. Muriatic acid is also disengaged from a boiling solution of the common muriate of soda, although in much smaller quantity, than from a solution of muriate of magnesia. Whether in the case of muriate of soda, the acid proceeds from a small residue of muriate of magnesia, or muriate of iron, I do not venture to determine. Neither of the bases (soda, magnesia) appears to pass over: at least, the distilled water leaves no residue when evaporated.

9. This yellow, reddish-brown, or dark-brown coloured solution of nitrate of silver, produced in so remarkable a manner by the deoxidizing action of aqueous vapour, retains its colour for a long time unaltered, but it at last deposits a dark-brown oxide of silver.

10. If previously to the introduction of aqueous vapour the solution of nitrate of silver be raised to the boiling point by the immediate application of heat, it does not completely retain its transparency after having been exposed as usual to a current of the vapour, but the discoloration which it sustains is greatly inferior.

The deoxidizing property of aqueous vapour, demonstrated beyond a doubt by the foregoing experiments, deserves to be still further investigated, and would, perhaps, already admit of some practical applications. It is my intention to continue my experiments on the subject. Before concluding, I may observe, that the vapour of water does not appear to produce any change upon a solution of corrosive sublimate, or upon solutions of the protoxide or peroxide of mercury in nitric acid,

ARTICLE X.

On the Transmission of Electricity through Tubes of Water, &c. By Mr. C. Woodward.

SIR,

(To the Editor of the Annals of Philosophy.)

June 5, 1824.

ON perusing the last number of your Annals, I observed a letter signed T. J., informing me " that the experiment of firing loose gunpowder by passing the charge of a leyden phial through tubes filled with water, and also on the conducting power of alcohol, ether, and acids, were made by a Mr. Lewthwaite, in May 1821; and are published in the eleventh volume of the Institution Journal:" "the natural inference of which, I apprehend, is, either that I published some experiments as new, which were not so; or that I gave as my own, the experiments of another.

If T. J. will refer to my letter, I think he will perceive that my object was to offer a theory in explanation of a singular phenomenon, and not merely to state the fact of the inflammation of loose gunpowder, or the conducting power of alcohol, ether, and acids. For this purpose I introduced the subject as briefly as I could, and then enumerated the experiments, which led me to conclude that the theory I offered was the cor

rect one.

"It was (observes T. J.) from reading this letter that I became acquainted with the experiment. This, however, was not the case with myself, as the effects of electricity on loose gunpowder, when transmitted through tubes of water, were communicated by me to Mr. Lewthwaite some time previous to the publication of his letter.

It is extremely painful to speak of one's self; therefore, in my last communication, I avoided any allusion to what I had done elsewhere; but considering myself now called upon to explain, allow me, through you, to inform T. J. that I introduced the experiment in my concluding lecture on Electricity, at the Surry Institution, in December 1820; observing at the same time, that I could not offer any theory in explanation, the experiment having been but a few hours communicated to me by my much esteemed friend, Mr. Knight Spencer, the Secretary to the Institution.

Early in 1821 I instituted a series of experiments to ascertain the cause; and, although I had then no explanation to offer, my experiments would have been presented to the public through the medium of one of the philosophical journals, had not the appearance of Mr. L.'s letter in the Institution Journal

superseded the necessity of it.-In 1823 I again introduced the subject in my course at the Surrey Institution-when the experiments and theory noticed in my former letter to you, were offered in explanation and I was induced to suppose my communication would not prove unacceptable, by the recent inquiries of some scientific friends who were anxious to know if I could explain the cause of so singular an effect among whom was Mr. Lewthwaite, the writer of the letter alluded to by T. J.

I now turn to a more pleasing part of the subject, that of investigating experiments.

"Would suggest (continues T. J.) that Mr. W. should repeat the experiment with the water tube. I am disposed to think Mr. W. is in error, when he says the intensity (measured we are to suppose by a pith ball electrometer), indicated, was from 10° to 15°." The supposition in the parenthesis is perfectly correct, and I can assure T. J. I have too often repeated the experiment, and made too many notes upon the subject in conjunction with my electrical friends, to be in error. I have very frequently succeeded in the experiment with a quart jar, when the electrometer has indicated an intensity of only 10°, but not invariably; hence I stated in my letter," an intensity of from 10° to 15° is generally sufficient." Had I noticed all the minute peculiarities I have observed on this head, my communication would have been much too long for insertion, and as no particular point turned upon the question, I considered it sufficient to express myself in terms to be understood by an Electrician, without unnecessarily intruding upon your valuable pages. I must, however, inform T. J. that the success of the experiment, with a low degree of intensity, will greatly depend on the quality of the gunpowder, as well as the care taken to prevent the dissipation of the electrical fluid, for with very coarse powder I have been unable to perform the experiment at all.

T. J. lastly observes, "it would have been more satisfactory if the degree at which the jar spontaneously discharged itself, had also been stated." This I confess myself at a loss to comprehend, for I have always found the spontaneous discharge of a jar, when mounted in the usual way, to depend as much upon what may be termed casual circumstances, as any experiment connected with electricity. At one time I have seen a spontaneous discharge take place at 50°; at another, the same jar, with the same electrometer, has been charged to 90°, without a spontaneous discharge. This suggestion, if reduced to practice, would be rather an expensive one to me, as my jars are all furnished with internal paper rims, according to Mr. Singer's plan-the metallic rods communicating with the inner coatings are passed through stout glass tubes, cemented New Series, VOL. VIII,

E

in the caps of the jars, and the uncoated surfaces are var nished, so that a spontaneous discharge seldom or ever takes place without fracturing the jar.

I am aware that the Pith Ball Electrometer is a very uncertain standard; and if my theory had depended on the degree of intensity required to produce the effect with a jar containing a given extent of coated surface, I should have used the balance electrometer, invented by Mr. W. S. Harris, of Plymouth, a description of which may be seen by referring to page 77 of "Observations on the Effects of Lightning on Floating Bodies, by W. S. Harris. London, 1823.”

I trust T. J. will continue the experiments, which, when well matured, he has promised shall be submitted to your consideration; and, if he thinks I am in error, or has discovered any facts which may militate against my opinions, I will either most cheerfully answer them in the true spirit of philosophy, which teaches us "to agree to differ," or I will prove to him that I am not wedded to any system, and that no one would more readily sacrifice a favourite theory, at the shrine of truth, than myself. Should he, on the other hand, require any information on a subject which has been for some years my favourite study, I shall feel much pleasure in making the communication, if in my power. I am, Sir, your obedient servant, CHARLES WOODWARD.

ARTICLE XI.

Some Observations on Mr. Penn's Theory concerning the Formation of the Kirkdale Cave. By James Smithson, Esq. FRS.

(To the Editor of the Annals of Philosophy.)

SIR, June 10, 1824. No observer of the earth can doubt that it has undergone very considerable changes. Its strata are everywhere broken and disordered; and in many of them are enclosed the remains of innumerable beings which once had life; and these beings appear to have been strangers to the climates in which

their remains now exist.

In a book held by a large portion of mankind to have been written from divine inspiration, an universal deluge is recorded. It was natural for the believers in this deluge to refer to its action, all, or many, of the phenomena in question; and the more so as they seemed to find in them a corroboration of the

event.

Accordingly, this is what was done, as soon as any desire to account for these appearances on the earth became felt.