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of Free Hydrogen and other Gases from Air. 3. Electric Resistance 

 Thermometry at the Boiling Point of Hydrogen. 4. Experiments on 

 the Liquefaction of Helium at the Melting Point of Hydrogen. 

 5. Pyroelectricity, Phosphorescence, &c. By James Dewar, LL.D., 

 D.Sc., F.R.S., Jacksonian Professor in the University of Cambridge, 

 and Fullerian Professor of Chemistry, Royal Institution, London, &c. 360 



Meeting of June 20, 1901, and List of Papers read 366 



On the Mathematical Theory of Errors of Judgment, with Special Re- 

 ference to the Personal Equation. By Karl Pearson, F.R.S., Uni- 

 versity College, London 369 



Mathematical Contributions to the Theory of Evolution.— X. Supple- 

 ment to a Memoir on Skew Variation. By Karl Pearson, F.R.S., 

 University College, London 372 



On the Structure and Affinities of Dipteris, with Notes on the Geological 

 History of the Dipterirlinae. By A. C. Seward, F.R.S., University 

 Lecturer in Botany, Cambridge, and Elizabeth Dale, Pf eiffer Student, 

 Girton College, Cambridge 373 



The Nature and Origin of the Poison of Lotus arabicus. By Wyndham 

 R. Dunstan, M.A., F.R.S., Director of the Scientific and Technical 

 Department of the Imperial Institute, and T. A. Henry, B.Sc, 

 Salters' Company's Research Fellow in the Laboratories of the Im- 

 perial Institute 374 



The Pharmacology of Pseudaconitine and Japaconitine considered in 

 Relation to that of Aconitine. By J. Theodore Cash, M.D., F.R.S., 

 Regius Professor of Materia Medica in the University of Aberdeen, 

 and Wyndham R. Dunstan, M.A., F.R.S., Director of the Scientific 

 Department of the Imperial Institute 37S 



The Pharmacology of Pyraconitine and Methylbenzaconine considered 

 in relation to their Chemical Constitution. By J. Theodore Cash, 

 M.D., F.R.S., Regius Professor of Materia Medica in the University 

 of Aberdeen, and Wyndham R. Dunstan, M.A., F.R.S., Director of 

 the Scientific Department of the Imperial Institute 384 



On the Separation of the Least Volatile Gases of Atmospheric Air, and 

 their Spectra. By G. D. Liveing, M.A., Sc.D., F.R.S., Professor of 

 Chemistry in the University of Cambridge, and James Dewar, M.A., 

 LL.D., F.R.S., Jacksonian Professor in the University of Cambridge, 

 Fullerian Professor of Chemistry, Royal Institution, London 389 



Further Observations on Nova Persei. No. 3. By Sir Norman 

 Lockyer, K.C.B., F.R.S , 399 



Total Eclipse of the Sun, May 28, 1900. — Account of the Observations 

 made by the Solar Physics Observatory Eclipse Expedition and the 

 Officers and Men of H.M.S. "Theseus" at Santa Pola, Spain. By 

 Sir Norman Lockyer, K.C.B., F.R.S 404 



Preliminary Statement on the Prothalli of Ophioglossum pendulum (L.), 

 Helrninthostachys zeylanica (Hook.), and Psilotum, sp. By William 

 H. Lang, M.B., D.Sc, Lecturer in Botany, Queen Margaret College, 

 University of Glasgow. Communicated by Professor F. O. Bower, 

 Sc.D., F.R.S 405 



