MEMOIRS AND PROCEEDINGS OF 7/197 THE MANCHESTER LITERARY AND PHILOSOPHICAL SOCIETY. Ordinary Meeting, October 1st, 1895. HENRY WILDE, F.R.S., President, in the Chair. The thanks of the members were voted to the donors of the books upon the table. Reference was made to the loss by death, since the last meeting, of Mr. JOHN LAWSON KENNEDY, Professor W. C. WILLIAMSON, LL.D., F.R.S., THOMAS HENRY HUXLEY, M.D., Ph.D., LL.D., D.C.L., P.P.R.S., &c., and M. LOUIS PASTEUR, Foreign Member R.S., Membre de l'Institut, &c., ordinary or honorary members of the Society. Mr. HENRY WILDE, F.R.S. (the Chair being taken by Dr. EDWARD SCHUNCK, meanwhile), read a paper on "Helium, and its place in the Natural Classification of Elementary Substances." A discussion ensued, in which Professor H. B. DIXON, F.R.S., Professor OSBORNE REYNOLDS, F.R.S., and others took part. The spectrum of helium obtained from Norwegian cleveite was exhibited, and a method of distilling the same gas from some heavy zirconiferous sand containing uranium, and found in large deposits on the coast of Brazil, was also explained and experimentally illustrated, the spectrum of the gas thus produced being likewise exhibited. Ordinary Meeting, October 15th, 1895. EDWARD SCHUNCK, Ph.D., F.R.S., F.C.S., Vice- The thanks of the members were voted to the donors of the books upon the table. Mr. W. H. JOHNSON, B.Sc., exhibited some filaments. of tin sent down to the coast of Africa from the interior, and received thence. This tin is the first which is known to have been received from the African interior. A discussion ensued as to the possibility of Africa having been a source of tin supply in prehistoric times for the bronze implements then in use, in which Professor H. B. DIXON, F.R.S., Professor BOYD DAWKINS, F.R.S., and others took part. Mr. HENRY WILDE, F.R.S., read a supplementary note on "The place of Helium in the Natural Classification of the Elementary Substances." Mr. W. E. HOYLE, M.A., M.Sc., Honorary Librarian, gave an account of the progresss of the rearrangement of the Society's library under the provisions of the Wilde endowment. The library is peculiarly rich in the serial publications of academies and learned societies for very many years past, and for these, in consideration of the variety of the subjects treated, an alphabetical classification according to countries and towns has been adopted. Mr. CHARLES L. BARNES, M.A., read a paper on "Science in Early England," containing an account of the writings of philosophers in this country from the seventh to the thirteenth centuries inclusive, and terminating with the works of Roger Bacon. On Helium and its place in the Natural Classification of Elementary Substances. By Henry Wilde, F.R.S. (Received October 1st, 1895.) The announcement made by Professor Ramsay that a gas from the mineral Cleveite showed the yellow spectral line of solar helium λ 5876, and was therefore identical with that hypothetical element,* was received by physicists with some amount of incredulity, as it was illogical to predicate the identity of any element from the near coincidence of a single line among the numerous lines which belong to other elementary substances in the gaseous condition. Nevertheless, the conspicuous brightness and comparative isolation of the chromospheric line D3, together with the statement by Crookes, that the yellow line of the cleveite gas was single,† in agreement with the reputed singleness of D3, gave some force to the idea that the solar and terrestrial gases were identical. Lockyer and Runge,§ however, subsequently discovered that the yellow line of the new gas was double, and the latter observer justly remarked "that the unknown element helium, causing the line D3 to appear in the solar spectrum, is not identical with the gas in cleveite unless D3 is also shown to be double." Runge further observed that the less refrangible of the two lines was much weaker than the other, and he found the difference in the wave-lengths of the lines to be 0.323 tenth metres. *Chemical News, March 29, 1895. + Chemical News, March 29, p. 151. § Nature, June 6, p. 128. The doubleness of the yellow line of the cleveite gas led directly to a closer observation of the chromospheric line by Huggins,* Lockyer, and Professor Hale of Chicago.† Each of these observers has found that the solar helium line is also double. Mr. T. Thorp, of Whitefield, the inventor of several valuable spectroscopic appliances to the telescope, has also, by means of a Rowland grating of 14,438 lines to the inch, and a fourth-order spectrum, divided D3. Through the kindness of Mr. Thorp, I have been able to confirm the observations which have, up to the present time, been made on the doubleness of the yellow line of solar helium. Not only is the doubleness of the chromospheric line established, but its components are of unequal width, and the weaker line is on the less refrangible side of the spectrum, as in the gas from cleveite. Professor Hale has determined the difference in the wave-lengths of the components of D3 to be 0357. Moreover, Lockyer has observed that five other prominent lines of the new gas coincide with the chromospheric lines 7066, 6678, 5016, 4922, and 4472. The only question now open for discussion as to the identity of solar and terrestrial helium is the difference in the wave-lengths of the double line as determined by the several observers. Crookes, as we have seen, pronounced the yellow line of terrestrial helium to be single. Ramsay subsequently observed the line double, and estimated the distance between them to be part of that between the sodium lines§=0'120 tenth metres. Runge and Paschen observed a difference of 0323 between the components of the yellow line, while Professor Hale, as I have said, makes the difference between the same components of solar helium 0*357. * Chemical News, July 19, p. 27. + Nature, August 1, p. 327. § Paper read before the Chem. Soc., June 20, 1895. In none of these observations of the characteristic yellow line of terrestrial and solar helium, would any account appear to have been taken of the influence of pressure and diffusion with other gases in varying the width of spectral lines, especially on the more refrangible side of the spectrum. I have already shown in my paper on the spectrum of thallium (Proc. Roy. Soc., 1893) that the expansiveness and brightness of the C line of hydrogen, at atmospheric pressure, masked completely one of the two principal lines in the visible spectrum of thallium for more than thirty years, so that the sharp red line in the arcand spark-spectrum of this element is not mapped in the recent tables of Thalén, and Kayser and Runge.* I have recently repeated some of the experiments of Ramsay and Lockyer on helium obtained by the distillation method from Norwegian cleveite, pitchblende, and other minerals containing uranium. The result of these experiments confirms the conclusion that the differences in the determination of the wave-lengths of the components of the characteristic yellow line are due to the same cause which masked the red line of thallium. The apparatus with which the experiments were made is shown in Plate I., one-fourth the actual size. It consists of a small steel cylinder heated from below by a Bunsen burner, or the oxyhydrogen-flame. A bent iron tube, of small bore, connects the cylinder with an airpump and a glass sparking-receiver in which the spectra of the gases are produced. The mouth of the receiver is plugged with a stopper of caoutchouc, through which are thrust a pair of iron wires terminating with platinum electrodes. Vacuum-gauges are mounted on the pump for measuring the amount of rarefaction in the cylinder and sparking-receiver to a small fraction of an inch of mercury. * Ueber die Spectren der Elemente, Pt. VI., Berlin, 1892. Brit. Assoc. Report, 1893, p. 403. |