TRANSACTIONS OF SECTION A. 621 



3. A Remarkable Feature in the Splash of a Rough Sphere. 

 By Professor A. M. Wortiiington, C.B., F.R.S. 



The object of tlie communication was to exliibit and explain instantaneous 

 photographs showing the remarkable change that occurs in the splash of a rough 

 sphere falling vertically into a liquid, when the height of fall is increased beyond 

 a certain critical value. (With a sphere of 1'5 cm. in diameter this critical heigli. 

 is reached below 140 cm. and above 70 cm. A further increase of height to 

 680 cm. — about 22| feet— makes no material difterence.) 



Below the critical height the splash is characterised by an upward jet thrown 

 high into the air, the origin of which had been traced by the author many years 

 ago. It is now found that when the critical height is passed the long cylindrical 

 column of air which follows the sphere in its descent through the liquid is pierced 

 by a central downward jet directed from above along the axis of the air-column. 

 The photographs show that this downward jet is due to the permanent closing at 

 an early stage of the mouth of the air-column by a film of the liquid, and to the 

 subsequent reduction of the pressure of the confined air througli the piston-like 

 action of the sphere when its momentum is large enough. 



(For details as to the method by which the photographs were taken and othei 

 information on the subject, reference may be made to the author's recently 

 published ' Study of Splashes,' Longmans, 1908.) 



4. Aiialogy betiveen Absorption from Solutions and Aqueous Condensatiou 

 on Surfaces. By Professor F. T. Trouton, D.Sc., F.R.S. 



On introducing a solid, such as cellulose, into a solution, say, of an aniline dye, 

 surface concentration or adsorption of the solute takes place in general, the 

 amount of Avhich is a function of the concentration and temperature. 



For equilibrium wuth a solution of given concentration the higher the tempera- 

 ture the less the adsorption is found to be ; but the adsoi-ption may be preserved 

 constant as the temperature is raised by increasing the concentration in a defitiite 

 manner. 



If curves are plotted, in terms of concentration and temperature as co-ordinates, 

 along which the adsorption is constant (from the analogy with adsorption of 

 water vapour by cotton these curves are called isoneres) it is found that all such 

 ciu'ves, drawn for difierent amounts of adsorption, are similar to each other, and, 

 further, they are found to be similar to the ordinary saturated curve for the solute 

 in question. 



This is analogous to the law of the isoneres for water vapour when wo sub- 

 .'^titute osmotic pressure for concentration and the saturation curveof the solution 

 for the boiling-point curve, that law being that at different temperatures the 

 pressure ordinate of a given isonero is a constant fraction of the corresponding' 

 ordinate of the boiling-point curve. 



Both relations were shown to follow from thermodynamic considerations. 



5. On the Effect of Pressure on the Boiling-point of Sul2)hur. 

 By Dr. J. A. Harker and F. P. Sexton. 



Within the past few years it has been recognised that the platinum-resistance 

 thermometer furnishes probably the most exact means we possess for temperature 

 measurements over a very wide range. As is well known, the three fundamental 

 fixed points, on which the scale of this instrument is based, are usually 0°, 100°, 

 and the boiling-point of sulphur. The latter point is used in the determination 

 of the characteristic constant of the particular kind of wire employed in the 



