below; but the metal which was near the bowl had its heat carried off faster than it could be supplied, and thus the temperature of the bath could show nothing more than the temperature of the bowl at the instant of projecting the water into it. The following remarks apply to the thickest iron bowl, or No. VIII., .25 of an inch thick.

One half a fluid ounce of water reduced the temperature of the bowl from 417° to a little below 212°, or through 205° Fah.

Three-quarters of an ounce, introduced at 504°, cooled the metal of the bowl below the point of repulsion for drops, or through about 120 degrees, the higher temperature of the metal more than compensating for the increased quantity of water evaporated. This bowl contained, up to the level of the bath, nearly three and a half fluid ounces. The surface was oxidated.

The following remarks apply to the temperatures of the metal when the water was first introduced.

The temperature of maximum vaporization for 4th of a fluid ounce, was above 480° Fah., but probably not very far. Between 569° and 628°, the time of vaporization of the same quantity of water increased from 10 to 20 seconds, or was doubled. The time at the point of maximum vaporization was about 8 seconds. With one-half of an ounce of water the probable temperature of maximum vaporization was about 504°, and the time of vaporization 11 seconds.

The different experiments with one fluid ounce of water, by comparison with a series in another bowl, indicated the temperature of maximum vaporization to be as high as 555°. At 518° and at 616° the times of vaporization were nearly the same; namely, 16 seconds.

The temperature of maximum vaporization, for two ounces, was above 600°; at 580° and at 602°, the times of vaporization were the same; namely, 24 seconds.

This quantity was as great as the experiment could be made with, satisfactorily.

From the results we see that the times of vaporization of quantities of water in the ratio of 1, 4, 1, 1 and 2, or of 1, 2, 4, 8 and 16, at the temperatures corresponding to the least time of vaporization, were about as 6, 8, 11, 13, and 22, or as 1, 1}, 15, 21, 33, not far from the ratio of the square roots of the quantities, which would have given 1, 1.4, 2, 2.8, 4.

The temperatures of the metal on which water being thrown will reduce it to such a degree, that the entire vaporization shall take place in the least time, increased for quantities varying from th of an ounce up to 2 ounces, or sixteen times, from about 460° up to 600°. The ratio of the temperatures above 212° was as 1 to about 13, indicating the approach to a temperature of the metal at which any large quantity of water introduced into a thick iron vessel, would be vaporized most rapidly.

This point was elucidated directly by heating a cast iron bowl, half an inch thick, in a charcoal fire; this bowl was of the same figure, nearly, with those already described, it could contain about ten fluid ounces of water. When heated to redness, being still kept on the fire, one fluid ounce of water was introduced, and lasted about 115 seconds: 4 ounces lasted in one experiment, 294 seconds; and in another, 304 seconds; and the red heat was not kept up in the dish: the water was repelled at first.

18. In the copper bowl, No. VII., the thickness being .07 inch, or about .36 of that of the iron, the following results were obtained, the same tin bath being used, and the surface of the copper being smooth.

At a temperature of 465°, 4th of a fluid ounce of water was repelled, the

repulsion being perfect nearly to the close of the experiment. This quantity required 175 seconds to evaporate. At the initial temperature of 501° the same quantity required 187 seconds to vaporize it. At the higher of these temperatures, in an iron bowl of nearly the same thickness, but in an oil bath, the maximum of vaporization was not reached.

One-fourth of an ounce required 13 seconds to vaporize it at 469° Fah., and 405 seconds at 529°, at which latter temperature the repulsion was perfect nearly throughout the experiment.

Three-eighths of an ounce vaporized in 12 seconds, at the initial temperature of 471°, and the metal in contact with the dish, was solid. At the initial temperature of 486° the same quantity required 30 seconds, and the repulsion was perfect for 15 seconds.

Five-eighths of an ounce vaporized in 15 seconds, at the initial temperature of 481°, and also at 5094°. The minimum time of vaporization being, probably, between these temperatures.

One ounce vaporized in 22 seconds, at 465°, as the initial temperature; in 16 seconds, at 486°, and the tin was found congealed beneath the cup; in 17 seconds, at 511; the minimum time being probably between 486 and 5114. Two ounces vaporized in 24 seconds, at 5114°, as the initial temperature; in 21 seconds at 526°, and in 22 seconds at 5564°; the minimum time of va porization being probably at or near 526° Fah.

From these results we see that between 471° and 486° Fah. 4, §, §, and 1 oz. vaporized in times differing but little from each other, the range being from 12 to 16 seconds; and that with two ounces, from 511° to 5564°, the time of vaporization was about four times the least of those just referred to. With quantities of water, varying from one-eighth of what the part of the bowl which was in contact with the bath, could contain, to one-half the capacity, the maximum vaporization was between 471° and 481°, and 481° and 511°, and the entire capacity of that part being filled, raised this temperature only to 526°.

This indicates the energy of the repulsion; for the evaporating surface being increased but about three times, and the water increased eight times, the initial temperature corresponding to the maximum of vaporization was raised but 56°. It shows, further, that with metal at this temperature, eight times the volume of steam was formed in three times the time, when the entire capacity was filled and compared with one-sixteenth of this capacity filled; the quantity of 6121 cubic inches of steam, or nearly 34 cubic feet having been generated in 42 seconds, at the initial temperature of 526°, the steam having atmospheric pressure.

The copper, which was bright when the experiments were commenced, became oxidated as they progressed, thus tending to raise the temperature of maximum vaporization.

Conclusions.

19. From the foregoing details may be deduced the following general conclusions, which will be found of practical importance.

1st. The vaporizing power of copper, when supplied with heat, by a bad conductor or circulator, such as oil, increases with great regularity as the temperature increases, up to a certain point, the water being supposed thrown upon the copper surface, in small quantities. Copper flues, heated by air passing through them, would be in this condition if left bare of water, and then ddenly wet. This holds with copper th of an inch thick, without indica

tion that a limit will be attained by a much more considerable thickness. The temperature at which the metal will have the greatest vaporizing power, is about 570° Fah., or about 230° below redness, according to Daniell.

The law of vaporization of small quantities of water, by a given thickness of copper, is represented with singular closeness by an ellipse, of which the temperatures represent the abscissæ, and the times of vaporization the difference between a constant quantity and the ordinates.

2d. The same power in thin iron, .04 (37) inch thick, increased regularly, and was at a maximum, probably, at 510°. With thicker metal the power increases more rapidly at the lower temperatures, and varies very little, comparatively, above 380°, with thicknesses exceeding 4th, and less than 4th of an inch; attaining a maximum at about 507° Fah., when the quantities are small; rising to 550°, and much above, as the quantity of water is increased relatively to the surface of the metal which is exposed. Quadrupling the quantity of water, the entire amount being still small, nearly tripled the time of vaporization at the maximum.

3d. When copper of th of an inch in thickness, was supplied with heat by melted tin, a worse conductor, and having a lower specific heat than copper itself, the time of vaporization, in a spherical bowl, of quantities varying fromth to of the entire capacity of the bowl, increased but three-fold, and the temperature of greatest evaporation was raised but 56°, or from 470° to 526°. When the bowl had half of the portion which was exposed to heat filled, the weight of the water was about one and one-tenth of that of the metal.

4th. The times of vaporization of different quantities of water, varying from th of an ounce to 2 ounces, in an iron bowl 4th of an inch thick, and supplied with heat by the tin bath, were sensibly, as the square roots of the quantities, at the temperatures of maximum vaporization for each quantity.

These temperatures were raised from about 460° to 600°, by increasing the weight of water about sixteen times, indicating that considerable quantities of water, thrown upon heated metal, will be most rapidly vaporized when the metal is at least 200° below a red heat.

5th. While a red heat, visible in daylight, given to a metal, even when very thick, and supplied by heat from a glowing charcoal fire, does not prevent water, when thrown in considerable quantities, from cooling it down so as to vaporize the water very rapidly, it is much above the temperature at which the water thrown upon the metal will be most rapidly evaporated. Thus one ounce of water was vaporized in 13 seconds, at about 550°, in a wrought iron bowl of an inch thick, and required 115 seconds to vaporize in a cast iron bowl an inch thick, at a red heat. Four ounces in the latter bowl vaporized in about 300 seconds, the bowl being red hot when it was introduced; and two ounces vaporized in 34 seconds at 600° Fah.

6th. The temperature of greatest vaporization, with a given thickness of metal, is lower in copper than in iron, the repulsive force being developed at a lower temperature. With equal thicknesses of iron and copper, the vaporizing power of the latter metal, at its maximum, was, with the oil bath, one-third greater than that of the former, and with the tin bath the power of copper .07 of an inch thick, was equal, nearly, to that of iron, 4th of an inch thick, each being taken at its maximum of vaporization, for the different quantities of fluid employed. As the maxima for the iron are higher than those for the copper, the advantage will be still greater in favour of copper when the two metals are at equal temperatures.

7th. The general effect of roughness of surface is to raise the temperature at which the maximum vaporization occurs, and to diminish the time of vapo

rization of a given quantity of water at an assumed temperature below the

maximum.

8th. Though it has been shown that water thrown upon red hot metal is adequate to produce explosive steam, even when it does not cool the metal down to the temperature of most rapid vaporization, it is not the less true that metal more than two hundred degrees below a red heat, in the dark, is in the condition to produce even a more rapid vaporization of water thrown upon it, than when red hot.

Stationary Temperature of Alcohol on heated Metals.

20. A curious fact was observed in regard to the temperature to which alcohol of the specific gravity .81, containing, therefore, 93 parts of absolute alcohol and 7 of water, could be raised in a heated dish. It is necessary, as an introductory remark, to recall the fact that when the temperature of a liquid is gradually raised, by applying heat to the vessel containing it, a limit is reached when the temperature of the liquid becomes stationary, the vapour given out in boiling carrying off the heat which enters the mass. When alcohol, of the strength above stated, was projected into a bowl heated above the temperature at which repulsion of the fluid takes place, the temperature of the liquid did not rise to its boiling point. In fact, the stationary temperature, instead of corresponding with that of ebullition, was lower as the temperature of the dish was higher. This experiment was made in the course of attempting to infer the probable temperature at which water might be repelled from the more readily attained temperature of the repulsion of alcohol. Not being of direct application to the subject before us, it was not carried as far as in other hands it would deserve.

Temperature of Alcohol vaporizing in a Copper Dish, .07 inch

Decision of the Circuit Court of the United States, for the Eastern District of New York, in a Patent case involving some important principles. To which is appended some remarks by the Editor.

UNITED STATES CIRCUIT COURT.

Before Judge Thompson.

Henry Stanley vs. Henry Hewitt.

This was an action founded upon a patent granted to the plaintiff, Henry Stanley, by the United States, the 17th December, 1832, upon a specification and application made to the patent office the 11th of October, 1832, for an improved rotary cooking stove. The plaintiff, by several witnesses, proved the originality of the invention in him, its importance and usefulness, and that the defendant had, from patterns taken from the plaintiff's stove, made and caused to be made and sold a large number of stoves, and was still pursuing the business.-The defendant to show that the plaintiff's patent was void; called Elisha Town and his son, and others to prove that in 1823 and 1824, he invented and procured to be cast a rotary stove, and that the plaintiff's stove revolved like it-also a Mr. Gould to prove that the plaintiff took the collars and flues in the cap of his stove from said Gould's stove, and also other witnesses to show that the plaintiff, as well as others, had used the collars and flues long before the plaintiff's improved cooking stove was invented; and also that the defendant attempted to show that the plaintiff had sold his stoves and given his invention to the public before he applied for his patent.

The plaintiff, in reply, called numerous witnesses to show that Town's stove, whatever it was, was useless, and had been abandoned as such; and that the plaintiff had no knowledge of it when he made his invention and improvement, and that his stove, in all the important improvements by him claimed, was wholly unlike Town's stove, and that collars and flues were not claimed by him as his invention, independently of his rotary plate in which they were attached, and that when they were put upon the Gould stove it was done at the plaintiff's suggestion. And that all the stoves delivered out before the application for the patent were delivered to be used on trial and with a view to test the utility of its improvements. The trial was a very laboured one, and occupied five or six days; but finally resulted in a question of law, growing out of the wording of the specification; which appeared to have been drawn up by the plaintiff without proper legal

advice.

On the part of the plaintiff it was insisted that the claim, in his summary, was for a combination of certain improvements he had made in the cooking stove connected together and attached to the top or cap of his stove, put in motion; and that it was the combination which he claimed, and not the parts forming the combination separately, and that his specification would bear that construction.

On the part of the defendant, it was insisted that the plaintiff had so worded his specification that it would not bear that construction, and that it really claimed the different parts comprising the top or cap of the stove separately and independently of any combination, and that his specification was otherwise defective.

Judge Thompson, in the progress of the cause, gave his opinion that putting the stoves out on trial and for the purpose of experiment and improvement, was not such a public use of them as would be considered as a dedi