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the circuit, and myself in another part of it. When the jar is charged to the usual high intensity, I will operate in the capacity of discharging-rod, by presenting the brass ball which I hold in my hand towards the ball of the jar. The result is the simultaneous discharge of the six pieces of ordnance, but not the slightest shock is experienced by myself, although the electric fluid that discharged the guns traversed my arms and chest, prior to its arriving at them.
Glass tubes, filled with water, have been employed in place of the wet string, in the process of firing gunpowder by electric discharges; but if the tube be too wide, the electro-momentum would be too great for any person to stand in the circuit without experiencing a severe blow; and even by long use of a narrow tube the electric momentum becomes too great for any person to stand in its way. I have employed a glass tube of narrow bore for several successive years, but I found that it gradually augmented the velocity of the transinitted electric fluid, till eventually I could not ignite gunpowder by its use : unless, indeed, I considerably augmented the quantity of Auid transmitted. This circumstance, I afterwards found, was owing to the nitric acid that had been formed by previous discharges, from the atmospheric air which the water held in solution, thus increasing its conduction, and giving greater freedom to the electric transmisssion.
This fact, which I have not seen mentioned in any other place, would not happen if a new portion of water were employed in every experiment, and the inside of the tube well cleaned.
' Another fact that I sometimes meet with, when operating on gunpowder, is that of setting the string on fire, at one or both of its ends, when they happen to get too dry by previous discharges.
Shortly after the discovery of electro-magnetism was made known in England, Sir Humphrey Davy magnetized steel needles by electrical discharges from a battery of Leyden jars; as will be seen by a reference to his excellent paper in these Annals.* But I am not aware that those experiments were ever varied by a change in the character of the circuit, prior to those which I published in 1826, in the Phil. Magazine. By those experiments I showed that, unless the electric fluid has a considerable momentum, steel needles are not magnetized by its influence whilst traversing a circuit from the Leyden jar.t
• Vol. vii. † See the first and second papers in No. 47, of these Annals.
We have heard nothing further respecting the enquiries of T. H. than that our letter, a copy of which appears
page 221, Vol. 6, had been received. The Editor of the Nautical Magazine, merely acknowledged it on the cover of his No. for April, 1841. The “Reviews" which Mr. B. thinks necessary to be continued, are
not lost sight of. We have a long time ago been advised, by one of the first chemical philosophers in the land, to carry them on in regular series. Want of time alone, has prevented us undertaking the arduous task. We are aware of the importance of such an undertaking were it for no other purpose than that of exhibiting, to the writer of those papers, the propriety and importance of rectitude, candour, and consistency. We are of opinion that a series of commentaries, properly conducted, and in the same order that the papers have appeared, would be exceedingly interesting.
Dr. Faraday has refused answering Dr. Hare's second letter, Annals, Vol. 7, p. 351, and declined any further public discussion with him on the points at issue.--Silliman's American Journal.
Prize Volumes for the latter half year of 1842. 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 platinum wire, of both of an inch diameter.
4th. For any magnet that will suspend 1 cwt., with the cross-piece at one inch distance from the poles.
END OF VOLUME EIGHT.
INDEX TO VOLUME EIGHT.
Edmund, on the Constant Voltaic Battery 454
by Simple Contact 422
his Electrical Experiments 377
Buff, Dr., on the Voltaic Pile
on Quantity and Intensity in Ditto
Calotype Paper, on the Preparation of
(22, Note). 337
369, 422, 423
152, 246, 277, 322, 76, 119
125, 216, 333, 131
363, 364, 365
his Experiments with Volta's Plates
his Single Gold Leaf Electrometer