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IV. The Halogen Hydrides as Conducting Solvents. Part I. The Vapour 

 Pressures, Densities, Surface Energies and Viscosities of the Pure Solvents. 

 Part II. The Conductivity and Molecular Weights of Dissolved Substances. 

 Part III. The Transport Numbers of Certain Dissolved Substances. 

 Part IV. The Abnormal Variation of Molecular Conductivity, etc. 



By B. D. STEELE, D.Sc., D. MC!NTOSH, M.A., D.Sc., and E. H. ARCHIBALD, M.A., 



Ph.D. (late 1851 Exhibition Scholars). 



Communicated by Sir WILLIAM RAMSAY, K.C.B., F.lt.S. 

 Received February 1, Read February 16, 1905. 



PART I. 



The Vapour Pressures, Densities, Surface Energies and Viscosities of the Pure 

 Solvents. By D. MC!NTOSH and B. D. STEELE. 



ALTHOUGH our knowledge of the ionising power of non-aqueous solvents has been 

 considerably increased during recent years by the investigations of WALDEN, 

 FRANKLIN, KAHLENBERG, and others, the liquefied halogen hydrides and sulphuretted 

 hydrogen have received little or no attention. 



GORE (' Phil. Mag.' (4), 29, p. 54), who experimented at ordinary temperatures, 

 found that the hydrides of chlorine, bromine, and iodine were very feeble conductors. 

 BLECKRODE ('Pog. Ann.' (2), 23, p. 101) stated that hydrogen bromide conducts 

 slightly; while HITTORF ('Pog. Ann.' (2), 3, p. 161, 4, p. 374, considered these 

 substances to be non-conductors. 



With regard to their behaviour as solvents, SKILLING ('Amer. Ch. Jl.,' 1901, 

 26, p. 383) found that at ordinary temperatures sulphuretted hydrogen dissolves 

 potassium chloride freely ; but that the solution is a non-conductor of electricity. 



HELBIG and FAUSTI (' Zeit. fur angewandte Chemie,' 1904, 17) state that stannic 

 chloride is soluble in hydrogen chloride, but that this solution also is a non-conductor. 



As it seemed highly improbable to us that sulphuretted hydrogen, which is 

 analogous to water in so many ways, should be devoid of dissociating power, we 

 decided to investigate its solvent action systematically, and at the same time to 

 examine the hydrides of chlorine, bromine, iodine, and phosphorus. 



VOL. CCV. A 390. O 2 23.8.05 



