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weighs near 3 tons, and to open the opposite valve against the momentum of such a column, gives the engine a shock that seems to endanger every part of it. In endeavouring to work with its full power at a speed of 20 strokes a minute, this shock is so severe, as to occasion a very perceptible stop in the return of the stroke, during which the water of condensation mounts into the cylinder. Two methods were proposed to remedy this inconvenience, which amounts to a perfect uselessness of more than of our power. 1st, to place a large plug-valve E, Fig. 9, in the rising pipe close to the pump, having as much water-way through its seat at a very small rise, as the whole pipe. This valve would shut instantaneously at the end of the stroke, catching the falling column of water, and nothing would oppose its immediate return. 2d, to place an air-vessel so as to act on the whole column. By this means the fall of the water would be entirely prevented. I regret that though this apparatus was provided, and could easily have been put up, in the course of a few days, circumstances prohibited the trial of them, and that I can only submit them as projects.-Could this pump be used with the same speed as the single pump, one half of the power of every double pumping engine, which works a single pump, would be saved; for the beam would need no counterpoise, and all the expense and friction of a second pump, where two are employed to balance each other, would be avoided.

I hope shortly to deliver you a second report on this subject, and am with true respect yours.

Read May 20th, 1803.

B. HENRY LATROBE.

Since the above was read in the Society I have constructed another and much larger iron boiler on this plan, the former having fully answered my expectation. In the new boiler I have passed the fire through a second flue above the other, which is immersed in the steam only, from which I promise myself great advantage. B. H. L.

The wooden boiler above described was planned and the erection of it commenced in July, 1801. The cast-iron boiler was projected in the latter end of January 1803.

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No. XX.

Account of the fusion of Strontites, and volatilization of Platinum,
Communicated

and also of a new arrangement of apparatus.
by Robert Hare, junr. member of the Society.

Read June 17th, 1803.

IT is known, I believe, to some of the members of the Philosophical Society, that a memoir on the supply and application of the blowpipe, which I had presented to the Chemical Society, was published in the commencement of last summer*. This memoir contains a description of a machine, termed an hydrostatic blowpipe, calculated to confine or propel the gases, for the production of heat, or other purposes; also an account of some experiments, in which by a concentration of caloric, till then unattained, substances were fused, which had been before deemed infusible. It was mentioned that alumine, silex, and barytes, were found susceptible of rapid fusion, and that the fusion of lime and magnesia, though extremely difficult, was yet, in a few instances partially attained. Platinum was described, as not only susceptible of fusion, but even of volatilization.

Being induced, last winter, to reinstate the apparatus, by which these experiments were performed, I was enabled to confirm my judgment of the volatilization of platinum, by the observation of Drs. Woodhouse and Seybert; for in the presence of these skilful Chemists, I completely dissipated some small globules of this metal, of about the tenth of an inch in diameter. In fact, I found platinum to be equally susceptible of rapid volatilization, whether exposed in its native granular form, or in that of globules, obtained from the orange coloured precipitate of the nitro-muriatic solution, by the muriate of ammoniac.

* Republished in the 14th volume of Tillock's Philosophical Magazine, and also in the annales de Chimie vol, 45.

About the same time, I discovered Strontites to be a fusible substance; for, having obtained a portion of this earth pure, from a specimen of the carbonat of strontites of Argyleshire in Scotland, I exposed it on charcoal to the flame of the compound blowpipe, after the manner described in my memoir above alluded to*. It became fused into a blackish semivitrious mass, in shape somewhat semiglobular.

In the performance of these and other experiments, I was associated with Mr. Benjamin Silliman, a gentleman of science and ingenuity, who had a short time before been elected Professor of Chemistry and Natural History, in Yale College, Connecticut.

In the course of our operations, having occasion for large quantities of the gases, we became desirous of avoiding the inconvenience of lading water in and out of the pneumatic tub, as this fluid rose or fell, in consequence of the filling or emptying of large air-holders and jars. This induced us to design an apparatus wherein this evil was avoided, and in which the pneumatic tub and hydrostatic blowpipe were united. This apparatus has since been executed by Mr. Silliman, in the laboratory of Yale College: and, as it proves to be convenient in operations requiring large quantities of the gases, I think it not improper to lay a drawing and description of it before the society. The drawing differs a little from the original, in the arrangement of parts, where alteration is obviously advantageous.

As the apparatus to be described, is little else than an union of the hydrostatic blowpipe, and pneumatic tub, it will of

• In that memoir I ventured to distinguish this flame by the word gaseous. This appellation has been objected to, as not sufficiently distinctive-an objection since rendered valid, by the discovery of the gaseous oxide of carbon, which had been confounded with hydrogen; and also by the consideration, that it does not distinguish between the flame of the hydrogen and oxygen gases when perfectly pure, and when contaminated by other substances held in a state of

solution or mixture.

Certainly the term gaseous is equally applicable to the flame of the gaseous oxide, and to that of hydrogen gas; but it is equally certain that it was in direct opposition to the theory now almost universally received, that the editors of the New-York Medical Repository, declared all flame to be essentially gaseous: for it is well known that, with an exception for the combustion of the permanently elastic fluids mentioned above, flame is not ignited gas, but ignited vapour. However, as the term was badly chosen, I have written in the place of it, flame of the compound blowpipe, the propriety of which will appear from an inspection of the instrument by means of which the flame is supported, (See plate III. Fig. 2.)

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