26 The Properties of the Surface of Liquids. 



runs through one of the pores of a filter, the roughness of the 

 material of which the filter is made detains the external part of 

 the stream of liquid. It is a provision of surface tension that 

 salts dissolved in the liquid tend to aggregate at the exterior 

 rather than the centre of the stream. Hence they are caught 

 by the filter. He proceeded to illustrate the fact that the force 

 due to surface tension was by no means inconsiderable, 

 contrasting it in this respect with gravitation, and demonstrated 

 by experiment how it was that straws, twigs, and other small 

 articles floating upon the water collected into clusters. Some 

 of the least complicated methods of measuring surface tension 

 were briefly referred to and illustrated, after which the lecturer 

 concluded with an experiment which showed that owing to 

 some occult cause the presence of electricity altered the size of 

 the drops composing a jet of water. 



A vote of thanks to the lecturer was proposed by Professor 

 Everett, who paid a high compliment to Mr. Barcroft for the 

 manner in which he had dealt with a difficult and intricate 

 subject. 



Mr. John Brown seconded, and the motion was passed by 

 acclamation. 



The proceedings then terminated. 



