14G Mr. J. W. Clark on the Behaviour of Liquids 



capillary action, as in the case of mercury. Drion * then took 

 up tho subject, and ultimately came to the conclusion that the 

 depression of the liquid in the capillary tube just before its 

 vaporization was the result of a less rapid expansion produced 

 by a difference of temperature too small to detect with a 

 thermometer. He described the surface of the liquid at the 

 moment of disappearance as perfectly plane, and the apparent 

 convexity as the result of refraction. 



MendelejefFt appears to have misunderstood Wolf; for in 

 1870 he writes : — " Wolf hat im Jahrl858 {Ann. de Chim.et de 

 Phys., t. 49, p. 259) gezeigt dass bei der Temperatur bei wel- 

 cher Aether in zugeschmolzenen Rohren ganz in Dampf ver- 

 wandelt wird der Meniscus verschwindet und dass Niveau 

 des Aethers in der Capillarrohre und in der weiten liohre 

 gleich ist. Die Beobachtung wurde von Drion (ibid. 1859, 

 t. 56, p. 221) bestatigt und erweitert." The researches of 

 Dr. Andrews J are too well known to need special reference 

 here ; and the discussion of a paper by Dr. Ramsay §, on the 

 " Critical State of Gases/' will be best left until the completion 

 of the work in part described in this paper. Messrs. Hannay 

 and Hogarth [| have recently shown that under certain con- 

 ditions solids may be dissolved in gases. Unfortunately, Mr. 

 Hannay's paper, u On the Cohesion Limit," recently communi- 

 cated to the Royal Society, is not yet printed; so that reference 

 to it must be left until a future occasion. 



In December 1878 I read a short preliminary note before 

 the Society, " On the Surface Tension of Liquified Gases," in 

 which the results of some measurements on sulphurous anhy- 

 dride at low temperatures were given If. Last year, at the 

 Society's meeting at the Royal Indian Engineering College 

 in June, a curve showing the height at which sulphurous 

 anhydride stands in a tube at temperatures between— -17° C. 

 and the critical temperature was shown, and the depression of 

 the liquid in a capillary tube, with some unsuccessful attempts 

 to determine the cause of it, were described. As this is the 

 last meeting of the session, I beg leave to lay the result of the 

 inquiry before the Society. 



* Ann. de Clxim. etdePhys. 1859, p. 221 ; and Comptes Bendus, t. xlviii. 

 1859. 



t Pogg. Ann. 1870, Bd. 141, S. 621. 



X Phil. Trans. 1869, p. 575 ; ibid. 1876, p. 421. 



§ Proc. Poy. Soc. vol. xxx. p. 323. 



|| Ibid. xxix. p. 324 ; ibid. xxx. pp. 178 and 188. 



*jl I have since found that the value then given is considerably too low, 

 no correction for the diameter of the external tube having been made. To 

 Professor Quincke I am greatly indebted for having directed my attention 

 to the previously reasoned observations of Wolf and Drion here quoted, 

 and for having kindly supplied me with most of the above references. 



