the Black Spot in Liquid Films. 

 Table IV. (continued). 



513 



gs 



frp 



© O 



Obs. VIII. — Sealed 6 days ; falling, temp. 



i 



6 





53 

 53 

 53 



33-4 

 19-2 

 18-4 



2-00 

 1-15 

 110 



18-2 

 17-5 

 17-5 



» 



Obs. IX. — One side unsealed, 16 hours. 





53 



217 



1-30 



17-2 



5 



52 



13-6 



•80 



17-2 



8 



51 



11-3 



•65 



17-2 



28 



42 



8-4 



•40 



17-2 





34 



7-7 



•30 



17-4 



4* 



33 



6-7 



•25 



176 



20 K 



Obs. X.- 



-Exposed ; 20 per cent, glycerine. 







52 



290 



1-70 



222 



h i 





10 



52 



220 



1-30 



22-8 





l 



50 



52 



22-0 



1-30 



235 





5 







49 



235 



1-30 



23-5 



>) 



Table IV. — This was taken Oct. 18th and the ten days 

 following on a 1 : 70 oleate-of-soda solution. The solution was 

 then drawn out and 20 per cent, glycerine boiled with it. 

 Only part of a few of the observations are given, the object 

 being to illustrate the effect of exposure and change of tem- 

 perature on the thickness of the films. 



Observation I. — These readings were taken soon after the 

 solution was prepared, and as soon as it had cooled down to the 

 temperature of the room. The films were freely exposed. 

 Within three minutes the b 2 films had formed on all of the 

 frames. 



Observation II.— -At the end of Obs. I. the casing was 

 partially sealed and II. taken three hours later. The mean 

 thickness was greater and did not fall so rapidly, though the 

 same might have been the case (judging from other obser- 

 vations) had there been no sealing. 



Observation III. — This was taken Oct. 19th, 24 hours later, 

 with the same sealing, and shows about the same thicknesses 

 as in II. 



Observation IV. — This was taken Oct 20th, the solution 

 having been firmly sealed 10 minutes when the frames were 

 raised. The second reading gives 11*7 as the limiting thick- 

 nesses of the b x films. At the end of four hours not all had 



