of Edinburgh, Session 1874-75. 
485 
b. Determination of the Surface-Tension of Liquids by the Ripples 
A slight modification of a formula given by Sir W. Thomson 
(Phil. Mag. ii. 1871), shows that the period ( t ) of oscillation of a 
particle in a deep mass of liquid agitated by simple waves or 
ripples is 
where A is the wave-length, T the surface-tension, and p the 
density of the liquid. By producing, with the aid of a massive 
tuning-fork, steady ripples in various liquids all subjected to the 
same conditions, and measuring micrometrically the length of these 
ripples, the quantity T is determined with considerable accuracy 
from the above formula. 
c. Capillary Phenomena at the Surface of Separation of two 
The only difficulty in this investigation is the selection of two 
liquids, neither of which will line the interior of the capillary tube 
so as to disturb the behaviour of the other. This was effected 
in various ways, most simply by employing water and sulphuric 
ether ; for when these liquids are shaken together and allowed to 
come to rest, the result is the production of a very sharply defined 
bounding surface between a weak solution of water in ether (above) 
and a weak solution of ether in water (below). The observations 
and measurements were made with contiguous portions of the same 
capillary tube, — one dipping into the upper, the other into the 
lower, layer. 
The following Gentlemen were duly elected Fellows of 
the Society : — 
produced by a Tuning-Fork. 
A 
Liquids. 
Kobert Clark, Esq. 
The Hon. James Bain, Lord Provost of Glasgow. 
Dr T. S. Clouston, F.R.O.P.E. 
Thomas Fairley, Esq., Lecturer on Chemistry, Leeds. 
