212 Soap Bubbles of Long Duration [Jan. 19, 1917 



number of days elapsing- are again marked as abscissae. The dotted 

 ordinate shows, for example, that the laibble on the fifth day had nearly 

 90 per cent, of the original soap-glycerine replaced by water, and con- 

 sequently only 10 per cent, of the soap-glycerine which was present in 

 the orio^iiial solution then remained ; this was reduced on the fifteenth 

 day to only aljout 3 per cent., but afterwards the rate of dilution was 

 much less. 



This intrinsic dilution curve agrees in form with that in Fig. 14, 

 which shows the deduced rates of condensation per unit mass 

 (O'l mgm.) of the bubble with time. The one result follows from 

 chemical measures of the alteration of drainage composition, while 

 the other follows from the combined periodical observations of the 

 weight of drainage and the contraction of the bubble. 



The second part of this investigation dealing with Bubble- 

 Complexes I hope to detail in a future Discourse. 



W. J. Green, Esq., B.Sc, and J. W. Heath, Esq., F.C.S., Assistants 

 of the Royal Institution, have aided in the course of the enquiry. 



[J. D.] 



LONDON : PIUNTKU BY WILLIAM CLOWES ANI> SONS, LIMITED, 

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