On the Limit of the Liquid State. 



313 



Table XII. 

 Curves III, Fig. 2, and XI, Fig. 3. 

 Capillary Height of Alcohol under High Pressure. 



T. P in atmos. Cap. Ht. 



224-6 236-8 



220 224-9 26 



200 182-2 129 



180 145-3 207 



160 136 264 



140 128 1 312 



120 114 354 



100 100-1 391 



80 86-8 428 



60 79 458 



40 69 1 489 



20 66 517 



64-2 544 



From these tables we see that the capillary height of the liquid is 

 lowered by a gas under pressure impinging on its surface. Thus at 

 66*7 atmospheres (the critical pressure of alcohol), the capillary height 

 falls to zero at 235°"4, at 163"5 atmospheres of pressure zero is reached 

 at 230°-3 ; while at 236*8 atmospheres capillarity disappears at 224°'6. 

 It is curious to note that, although the capillary action had ceased at 

 these temperatures, the liquids had not assumed the gaseous state, as 

 Tables IV, V, VI, VII, and VIII show that in no case up to a pres- 

 sure of 183 atmospheres did the alcohol diffuse into the hydrogen at a 

 temperature below 234°. 



As capillarity is entirely a surface phenomenon, the surface tension 

 of a liquid seems to be weakened by the impinging of a gas under 

 pressure upon its surface, and this we might expect to be the case, as 

 we can imagine a constant disturbance of the surface of the liquid, 

 owing to the high velocity of the hydrogen molecules striking it ; 

 whereas, not being soluble to any extent, few hydrogen molecules 

 penetrate to disturb the liquidness of the interior. It would thus 

 appear that, under such conditions, capillarity is not a true measure of 

 the liquidness or cohesion of a fluid, and were the pressure high 

 enough the surface of a liquid might be made to disappear, while its 

 interior was in a truly liquid condition. This question can be most 

 readily settled by passing a liquid, whose surface tension has thus 

 been caused to disappear, through a capillary tube, and observing 

 whether increase of temperature diminishes the time of flow, for the 

 resistance of a fluid is decreased by increase of temperature, while that 

 of a gas is increased. The experimental realisation of such a test 

 is difficult, but apparatus is being at present constructed for the trial. 



