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matter at a temperature of 60° F. and barometer 30°. If we consider these gases to have entered the flues at a temperature of 1020 Fah., their bulk will have been increased three-fold, or will have become 2,736,464.22 cubic feet.
Now, the least cross area of the Alues is 55,906 square feet, and at a velocity of 33.54 feet per second, or 120,741 feet per hour, there would be passed 4,049,753.76 cubic feet of gaseous matter, or 48 per centum more than required. Hence it appears that, so far from being any deficiency, there must have been a superabundance of oxygen supplied to the furnaces.
The Magnetism of Torsion.* We translate the following article from the French scientific journal L'Institut, of the 19th instant, on the subject of magnetic currents of induction produced by the torsion of iron. This was a communication from M. Mertheim to the Academy of Sciences at its last sitting, and details the results of his experiments, which will be found to have an important bearing on several mechanical questions:
It has long been known that a thread of iron, submitted to the action of terrestrial magnetism, becomes permanently magnetic when made to undergo a considerable amount of torsion equally permanent. An explanation
a of this circumstance has been attempted, in saying that the torsion acts in the same manner as every other mechanical disturbance, that it promotes the decomposition of the two magnetic fluids, and that at the same time it gives to the iron a certain coercive force. That opinion rests upon facts imperfectly observed. Torsion acts in a manner quite peculiar, in forcing the inetallic molecules to arrange themselves spirally, and in thus giving to matter itself the form which Ampère has assigned to inferior currents. Torsion produces temporary magnetic effects when it is temporary, and permanent effects when it is permanent; and these effects cannot be produced by any other mode of action of mechanical forces.
Temporary Effects.-A bar of iron, magnetized to the point of saturation, becomes partially demagnetized at the moment it experiences a temporary torsion, and remagnetized at the moment of contrary torsion, (detorsion), or, in other words, it is traversed by an inverse current during the torsion and by a direct current during the contrary torsion, whatever may be the direction in which this torsion takes place.
We understand by magnetization to saturation,” the state of magnetic equilibrium in which a bar of iron is when it has received all the magnetic excitement it is susceptible of acquiring under the action of a given current, or which, after the interruption of that current, has already lost all which it was unable to keep. So long as that equilibrium is not established, torsion and contrary torsion only act as other mechanical disturbances.
The manner in which the experiment is made is as follows:-A bar of iron, well heated beforehand, 1 metre in length (nearly 40 inches), and 15 milliinetres in diameter (nearly six-tenths of an inch), is rigidly fixed at: • From the London Mechanic's Magazine, December, 1852.
one of its ends, while the other is placed in the centre of a wheel, by means of which torsion in contrary senses can be produced upon it. It has two spirals, of which one is intended to receive the current of a single element of Daniell, while the other serves as a spiral induction. The latter is placed in communication with a galvanometer sensible to the astatic needle. It is unnecessary to observe that the two spirals are sufficiently remote from one another to prevent direct induction.
The establishment of the current causes the needle to move through an angle > (greater than) 90° towards the right. The north pole is found to fit into the spiral (encastré), and the south pole is twisted. When the current is made to pass in the contrary sense, the south pole of the bar fits in the spiral, the north pole is twisted, and the needle revolves towards the left.
The following table will exhibit at a glance the results of the experiment:
The coercive force in every mass of iron may be measured by the number of torsions necessary to make it attain the point of saturation.
Permanent Effects. When a bar of iron or a bundle of threads, has been magnetized by means of strong permanent torsion under the action, whether of the terrestrial current or of any other, it does not prevent the phenomena of an ordinary magnet. All torsion—temporary or contrary torsion-which acts upon it in the direction of permanent torsion, produces magnetization, or a direct current; and all torsion, or contrary torsion, which acts in the opposite direction, produces demagnetization, or an inverse current.
This experiment is easily performed with two bundles of the same iron thread, suspended vertically, and twisted so as to make of the one a helix dextrorsum, and of the other a helix sinistrorsum. They both have their north poles above, and their south poles below, and upon their being introduced into the spiral, the needle is moved towards the right. But after having placed the north pole of each bundle in the spiral, if temporary torsions be given to the south pole, it will be found that a lorsion in the same direction will produce contrary currents, according as it is applied to the one or to the other of the two bundles.
The following results are obtained:
It is only necessary, therefore, to add to the apparatus a commutator, to reverse the direction of the current after each semi-oscillation, in order to obtain, by means of the turning vibrations, a continuous current which may be rendered highly intense.
These facts appear to me (M. Wertheim) likely to raise theoretical questions of extreme importance. I propose to discuss them in a work on the torsion of solid bodies in general, upon which I have been long occupied.
For the Journal of the Franklin Institute.
Have we a New Power? The caloric ship Ericsson has since her trial early in January, made a trip to Washington for the purpose of demonstrating her success, and also of obtaining for Capt. Ericsson a contract from the government for one or more first class war vessels. Unfortunately for the community, (and also I think, for those who have invested their money in the enterprise,) no disinterested persons competent to judge were allowed on board, and to form an opinion from the reports of Capt. Ericsson or Capt. Sands, would be unfair; for the former is so deeply interested in the enterprise as almost to form a part of it, while the latter is unacquainted with machinery, and has given much of his testimony on hearsay evidence; there was no one on board to note the revolutions, weigh the coal, etc. The gentlemen interested in building this ship have been (it is understood) well pleased with the mystery that has been hanging around all their movements, and they are certainly entitled to the credit of having supported the enterprise with much cordiality, when even they were allowed to know but little of its details. I presunie that a portion of this zeal may be attributed to the expectation on their part, of large profits; for the promise of a saving in fuel of 80 per cent. will convince many a man who will hold out against the prospect of fair returns. But to return to the ship. On a visit to Washington recently, I conversed with several engineers who visited her while she was at that port, and saw her engines in motion (the vessel being at anchor). The number of revolutions per minute was from 4 to 41; the fires were burning bright, and in their opinion, 6 to 8 tons would be the consumption per 24 hours; wheels, 29 feet diameter; paddle, only about 12 inches wide, and dipping under very slightly. Whatever may be the final termination, it is certain that up to the present time the results obtained have not equalled the expectations of the originators of the enterprise. The working pressure is but 8 lbs. instead of 12, and as a consequence, the paddle wheels have been reduced in diameter, and one half the paddles removed. While I really hope that the engine will succeed, and a new power more economical than steam be introduced to the world, I must say that the profound mystery that has been connected with the Ericsson goes far in my mind, to stamp the whole thing as a failure.
For the Journal of the Franklin Institute. To the Committee of Publications:
GENTLEMEN :—The inclosed diagrams were taken from one of the engines of the steamer George Collier, a large first class cotton boat running between New Orleans and Memphis. I could not obtain the dimensions requisite for an analysis of her performance; she carries 850 tons of freight,
No I. Throttle open,
.25 inch. Revolutions per minute,
121 Difference between boiler pressure and engine pressure,
26 Mean pres. throughout the stroke, 76 Horses power, each engine, 266
2 lbs. 89.9 353
250 miles every 24 hours, with 50 cords of the ordinary river wood; her wheels are 34 ft. in diameter, with 11 ft. length of bucket; her valves are of the "balance poppet” kind, and cut off at io-ths from the commencement of the stroke; the diagrams taken with a wide throttle” show that the openings are slightly cramped, and that the exhaust valves, or passages, are not large enough; her boilers, furnaces, and heaters are similar to the Magnolia's, but not constructed by the same engineer. The “balance poppet” valve was used on the Mississippi fifteen years ago, and found to be so troublesome to keep tight, with the excessive high pressures used, that it was abandoned; within the past four years it has been introduced again, but although with better success than formerly, it is superseded by the double poppet;” and all the new boats of the larger class are supplied with engines fitted with the latter.
SAMUEL H. GILMAN. Baton Rouge, La., Feb. 24th, 1853.
For the Journal of the Franklin Institute. A New Apparatus for the Determination of Carbonic Acid with Fine
Balances. By CHARLES M. WETHERILL, Ph. D., M. D. The apparatus of Fresenius and Will, for the determination of carbonic acid in certain carbonates, has so generally pleased chemists, that it has been almost universally adopted. As the results have been found by repeated experiment to be very accurate, it has been sought with various success, to modify the form, and to lessen the weight, in order to adapt it to the fine balances in ordinary use. A modification of this kind has been described by Max. Schaffner, in the Chemical Gazette, 1853, p. 37, which consists in placing the sulphuric acid in a large test tube, and the carbonate in a smaller one inside the former. In constructing one of these apparatus, I met with certain practical difficulties. The exterior test tube must be taken rather large; if the glass is thin, it risks breaking in fitting the cork; if the glass is thick, the apparatus is heavy. It is rather difficult to obtain a large cork, which will close sufficiently well. The interior test tube is so small, that but a small portion of the carbonate can be accommodated; and, if rich in carbonic acid, it requires a little care in bringing the acid upon it to avoid projecting a portion of the liquid from the tube. The perforation of the corks requires a little care in adjusting, so that the inner tube will readily enter. There are several joints where leakage may ensue, and the corks will have to be frequently removed. The large cork fitting the exterior tube, presents a large surface to hygroscopic action, and the apparatus, as described, will not suit such carbonates the gas of which requires to be set free by hydrochloric or nitric acid. I have no doubt that it would give accurate results in the hands of a skilful manipulator, and it might be improved, either by placing the acid in the small tube, or better by forming it of two separated test tubes smaller than the exterior one, and united as in Fresenius and Will's apparatus.
On the above mentioned grounds, I was led to endeavor to contrive one which would obviate the disadvantages attaching to similar apparatus,