1917] 



on Soap Bubbles of Long Duration 



211 



Fig. 15 shows the parabolic increase in the weight of the 

 " drainage," with time ; on a separate scale of ordinates, on 'the 

 right-hand side, is marked the multiple of the original bubble 

 weight equal to the amount of liquid collected. The three points 

 marked are : — 



(1) 0*5 o'l-m. of liquid in 1 dav ; being over 5 " bubble weights." 



(2) 0-9^,, „ 9 days; „ 10 

 0-3) 1-0 „ „ 21 „ „ 11 



At each of these points the composition of the drainage, as well 



lOO/o 



Fig. 16. — Altering Composition of Bubble when Diluted by 

 Condensation of Water. 16 cm. air bubble. 



as the actual weight of the bubble which had then been washed 

 away, were as follows : — 



(1) 3*4 per cent, soap-glycerine ; 64 mgms. of original bubble 

 washed away. 



(2) Further 0*85 per cent, soap -glycerine ; 80 mgms. of original 

 bubble now washed away. 



(8) Further 0*29 per cent, soap-glycerine ; 86 mgms. of original 

 bubble now washed away. 



In Fig. 16 the ordinates on the left show the decreasing percentage 

 of soap-glycerine in the bubble, and on the right the consequent 

 increase in the percentage of water, as the experiment proceeded. The 



