191<s] Studies on Liquid Films 359 



WEEKLY EVENING MEETING, 



Friday, January 18, 1918. 



His Grace the Duke of Northu3iberland, P.O. K.G. 

 LL.D. F.R.S., President, in the Chair. 



Professor Sir James Dewar, M.A. LL.D. D.Sc. F.Pt.S. M.Pt.L, 

 Fallerian Professor of Chemistry. 



Studies on Liquid Films. 



Some problems presented by liquid films were discussed in the 

 Discourse of 1917.* These studies have been continued and further 

 developed in the restricted time left for research after meeting the 

 demands of Government Departments ; but such conditions imply 

 a certain amount of discontinuity which cannot but leave its mark on 

 the inquiry. 



Bubbles Four Feet in Diameter. 



In order to increase the size of bubbles above those described a 

 year ago (46 cm. in diameter), advantage was taken of a cool 

 cement-lined cellar (some 6(»0 cubic feet capacity) which was so 

 fitted that the nozzle and blowing tube w^re passed through the door 

 and controlled from outside. All apertures and cracks were filled 

 with glycerined cotton wool. The atmosphere of the cellar was 

 several times cleaned and renewed by pumping in purified air, but 

 no permanent purity could be maintained. In less than two days 

 the Tyndall cone would reappear. Large sheets and trays smeared 

 with glycerin were of no assistance in reducing the mist, so that 

 although bubbles up to four feet in diameter were obtained, they did 

 not last above a few hours. 



Plane Black Films 2500 Sq. C3i. in Area. 



At the Discourse given a year ago a stoppered vessel was shown 

 which contained a plane black film 19 cm. in diameter; the film 

 was then one week old, and has remained unchanged to this date. 



* " Soap Bubbles of Long Duration," Proc. Roy. Inst., Vol. XXII. p. 179. 



Vol. XXII. (No. 112) 2 c 



