510 



Mr. E. S. Johonnott on the Thickness of 



thicknesses correspond closely to those in Table I. The 

 limiting thickness of the b x films appears here as in Table I. 

 to be about 12 jju/jl. 



Table III. — This was taken October 13th with a 1 : 70 oleate 

 of soda solution to which 10 per cent, glycerine had been 

 added. The casing had been sealed 24 hours. The most 

 noteworthy feature is the great thickness and its slight 

 increase at the beginning. This increase at the beginning 

 has often been noticed with other solutions. The thickness 

 fell to 28*6 fjLjju at the end of the 6th hour. The brass plate 

 was then continuously heated for an hour while close to the 

 casing, and the thickness fell to 11*5. No further thinning 

 could be produced, even by heating the casing directly with 

 the burner. The plate was then removed, and the temperature 

 fell from 33°*4 C. to 25°, while the films came back to a mean 

 thickness of 35 ^\x. Something similar to the b 2 films 

 appeared on a few of the frames^ but was never distinct as 

 with the pure oleate solutions. 



Table I. 

 1 : 40 Oleate of Soda Solution ; sealed 2 hours. 



Age of Films. 



O . 



go 







u 





- 5G 



s a 



go G 



c3 g 



<o 



hours. 



mins. 



J5 «D 



a 2 





1 



03 







& 



H 



fi 



H 



Q 







52 







25 



*l 





"2 



51 



27 V 6 



1 : 6 



24-6 







5 



50 



21-2 



1-2 



24-6 



,, 





15 



49 



18-0 



10 



24-6 



,, 





30 



48 



155 



•85 



24-6 



,, 





45 



47 



16-0 



•85 





„ 



"l 



5 



47 



150 



•80 



24-6 



„ 



1 



25 



47 



15-0 



•80 





» 



1 



45 



47 



15-0 



•80 



24 V 6 



j> 



3 







44 



15-0 



•75 



24-6 



j> 



3 



15 



war 



med 









3 



15 



44 



13-1 



•65 





46 2 



3 



16 



42 



63 



•30 



25*2 



6 2 



3 



20 



42 



126 



•60 



252 



46 2 



3 



25 



42 



13-7 



•Go 





*i 



4 



5 



42 



137 



•65 



24-2 





4 



25 



42 



13-7 



•65 



24-2 



„ 



4 



45 



42 



15-8 



•75 



24-2 



)> 



5 



5 



41 



16-0 



•75 





,, 



5 



5 



w 



med 







,, 



5 



7 



41 



6-5 



•30 



25-2 



* 2 



5 



45 



36 



12-3 



•50 



24-8 



h 



