BIBLIOGRAPHY. Castle, W. E. :06. The Origin of a Polydactylous Race of Guinea-pigs. Carnegie Institution of Washington, Publication No. 49, pp. 17-29. Galton, F. '89. The Average Contribution of each Several Ancestor to the Total Heritage of the Offspring. Proc. Roy. Soc., London, Vol. 61, pp. 401-413. Parker, G. H. :03. The Optic Chiasma in Teleosts and its Bearing on the Asymmetry of the Heterosomata. Bull. Mus. Comp. Zool. Harvard Coll., Vol. 40, No. 5, pp. 219-242, 1 pl. Schmitt, F. :02. Über die Gastrulation der Forelle mit Berücksichtigung der Concrescenztheorie. Verhandl. d. deutsch. Zool. Gesellsch., 12te Jahresversammlung, Leipzig, pp. 64-83, 7 Fig. Schultze, O. '95. Die künstliche Erzeugung von Doppelbildungen bei Frosch Larven mit Hilfe abnormer Gravitations-wirkung. Arch. f. Entwickelungsmech., Bd. 1, pp. 269-305, Taf. 11 u. 12. Spemann, H. :01. Experimentelle Erzeugung zweiköpfige Embryonen. Sitzungsb. d. phys.-med. Gesellsch. Würzburg, Jahrg. 1900, pp. 2–9. Spemann, H. :01. Entwickelungsphysiologische Studien am Triton-Ei. Arch. f. Entwickelungsmech., Bd. 12, pp. 224-264, Taf. 5, 24 Textfig. Proceedings of the American Academy of Arts and Sciences. VOL. XLII. No. 13.- NOVEMBER, 1906. FLUORESCENCE AND MAGNETIC ROTATION SPECTRA OF SODIUM VAPOR, AND THEIR ANALYSIS. BY R. W. WOOD. WITH FIVE PLATES. INVESTIGATIONS ON LIGHT AND HEAT MADE AND PUBLISHED, WHOLLY OR IN PART, WITH APPROPRIATION FROM THE RUMFORD FUND. FLUORESCENCE AND MAGNETIC ROTATION SPECTRA OF SODIUM VAPOR, AND THEIR ANALYSIS. By R. W. WOOD. Presented by C. R. Cross. Received August 7, 1906. PREVIOUS work, which has been recorded in the Philosophical Magazine,1 convinced me that a careful study of the remarkable optical properties of the vapor of metallic sodium would, in time, furnish the key to the problem of molecular vibration and radiation. This opinion has been strengthened by the work of the past year, and though much remains to be done, it seems best to place the results already obtained on record. In no other case that I know of is the molecular mechanism so completely under the control of the operator. Its periodicities can be studied in a variety of ways: by absorption, by cathode-ray stimulation, by excitation with light, either white or monochromatic, and lastly by its remarkable selective magnetic rotation of the plane of polarization. The vapor is, in every case, that obtained by heating metallic sodium in steel or porcelain tubes, usually highly exhausted. From a study of the dispersion of the vapor, it seems probable that we may be dealing with clusters of molecules with which a certain amount of hydrogen may be associated. As I have shown in a previous paper, if a pool of sodium is heated in a highly exhausted horizontal tube, the top of which is cooler than the bottom, the vapor has an enormous optical density close to the surface of the pool, and a very small density along the roof, the nonhomogeneous layer acting as a prism. The only way in which I can reconcile this state of things with the kinetic theory is to assume that the vapor leaves the metal in the state of molecular clusters, which gradually break up into smaller clusters and eventually into molecules. This is of course only an hypothesis, and I mention it in the present paper merely to indicate that our vibrating mechanism may be an 1 Magneto-optics of Sodium Vapor, Phil. Mag., Oct., 1905. The Fluorescence of Sodium Vapor, Phil. Mag., Nov., 1905. A Quantitative Determination of the Dispersion of Sodium Vapor, These Proceedings, 40, 335. |