invented by him, and spoke of some of the applications of the gases thus prepared. Dr. Hare was under the impression that few chemists were aware of the great advantage of the self-regulating reservoirs of gas, to which he had resorted. He was enabled, by means of them, to keep hydrogen, carbonic acid, nitric oxide, chlorine, chlorohydric acid, sulphydric acid, and arseniuretted hydrogen, so as to use any of these gases at pleasure. He had kept these reservoirs in operation for months, without taking the constituent vessels apart. By means of the reservoir of chlorohydric acid he had been encouraged to make an effort which proved successful; to form artificial camphor by the impregnation of oil of turpentine with that gas. Subjecting an ingot of tin to a current from his reservoir of chlorine, it was rapidly converted into the bichloride, or fuming liquor of Libavius. To his surprise the ingot was fused by the heat generated. In the last mentioned reservoir the materials were manganese, in lumps, and concentrated chlorohydric acid, diluted sulphuric acid being also introduced; as the reaction of this last mentioned acid with the manganese was more active than that of the chlorohydric acid. In fact, sulphuric acid, diluted with its weight of water and common salt, might be used without chlorohydric acid. In the reservoir for chlorohydric acid, the materials were sal ammoniac and sulphuric acid, to which some water was added, but not so much as to prevent the chlorohydric acid from assuming the gaseous state. He had found it preferable to keep the sulphydric acid reservoir in a flue, the gas being drawn, when wanted, through a globe of water, by means of a leaden tube, at a convenient place. It would be desirable that the reservoirs of chlorine and chlorohydric acid should be similarly situated. Mr. Sears C. Walker made an oral communication on the subject of determining longitudes from corresponding observations of meteors. It had been recently remarked by Prof. Schumacher, Astr. Nachr. No. 283, that, so far as his information extended, no trial had been made of the observation of meteors for determining longitude; though the subject had been proposed long since by Prof. Benzenberg. Accordingly, on the 11th of August, 1839, observations, chiefly of the instant of vanishing of meteors were made at the observatories of Altona, Bremen, Konigsberg, Breslaw, &c. with such success as to D lead Dr. Olbers to the conclusion announced in a succeeding No. (284) that observations of this kind are adequate for the complete determination of longitudes of places. By means of twelve coincidences on the same night, Prof. Boguslawski found the Breslaw Observatory to be 28m 22s.07 east of Altona, differing less than a second from that which had been previously adopted. As the subject of priority in this inquiry might be considered important, Mr. Walker deemed it his duty to communicate the substance of a letter from Prof. Alexander, of Princeton College, New Jersey, dated January 14th 1839, in which is contained the result of seven coincidences of observations of meteors, made 25th Nov. 1835, by Messrs. A. D. Bache and J. P. Espy, at the house of Prof. Bache, in Philadelphia, and by Professors Henry and Alexander, at the Philosophical Hall, 0.18. east of Nassau Hall, College of New Jersey, at Princeton. As the time referred to by the Philadelphia observers is that of the University of Pennsylvania, which is about 0.78, west of the State House, Philadelphia, the differences of longitude, given by Prof. Alexander, have been diminished by 0.6s. to reduce them to the State House, Philadelphia, and Nassau Hall, Princeton. The results are contained in the table. The time of the disappearance of the meteors was noted. In order to judge of the degree of precision of this result, an extract of a letter from Robert Treat Paine, Esq. dated June 10th, 1839, was read, giving his determination of the same by transportation of three chronometers in May last, from Princeton to Castle Garden, New York, and thence to Boston, as follows: A further comparison was furnished from the observations of the solar eclipse of Sept. 18th, 1838, as reduced by Prof. Kendall, and from those of several occultations reduced by Mr. Walker. Comparisons with the High School Observatory. Assumed longitude-5h. 0m. 42s. Resulting longitude of Nassau Hall, 1838, Sept. 18th. Solar Eclipse four phases,-4 58 37.64 weight 2.0 Nov. 21, Ir. w Sagittarii, 34.62 1.0 Comparisons with the State House, Boston. Assumed longitude The Immersion of f Pleiadum was also observed by Prof. Boguslawski at the Breslaw Observatory, longitude 1h. 8m. 10.4s., whence Nassau Hall -4h. 58m. 41.15s. No. 5, weight 1. This result is somewhat uncertain, from the variation of the co-efficient of the unknown error of the moon's tabular place on a secondary to its orbit; since we have for the longitude, d — — 4h. 58m. 41.15s. 2.353 × -0.406 × ", according to Bessel's Notation. The mean results taken with their weights gave, Thus it appears that the observations of the 25th November, 1835, lead to the same conclusion as that which was subsequently in 1839, obtained by the European astronomers. Mr. DU PONCEAU, President, in the Chair. The Judges and Clerks of the Election, held this day, reported the appointment of the following officers: President. Peter S. Du Ponceau, LL. D. Nathaniel Chapman, M. D., Franklin Bache, M. D., John K. Kane, Alexander D. Bache, LL. D., Robley Dunglison, M. D. Counsellors for Three Years. Nicholas Biddle, Thomas Biddle, Gouverneur Emerson, J. Francis Fisher. Curators. John P. Wetherill, Isaac Hays, M. D., Franklin Peale. Treasurer. John Vaughan. A |