191s] on Studies on Liquid Films 399 



leng'th meantime had Ijeeii reduced from 5:> * ii to 50 * 9 cm. ; after 

 this the free bubbles remained on the nozzle a fmther 53 days. 

 They were then replaced by the second set already described, which 

 took 64 days before it divided. The third set which followed was 

 more uniform, consisting of one segment, top and bottom, each of 

 whose volumes was half a htre, while the four in the middle con- 

 tained one litre each. This set parted in 40 days. 



Very good black columns were also obtained in the long glass 

 cylinder (Fig. 6). With this it was possible to prevent undue 

 straining of the segments by carefully raising the support ring when 

 necessary. The cylinder was long enough to get in ten segments, 

 each of over 250 c.c. A thin thread of stranded cellulose (artificial 

 silk) was sometimes fixed both at the nozzle and support ring to lie 

 along the outer contour of the column from top to bottom. This 

 not only stabilised the column while being blown, but accelerated the 

 drainage and black development, because any excess liquid in the 

 Gibbs ring channels of the junction planes was quickly drawn into 

 the capillary canals of the silk. The result was that the black stage 

 was complete in one day, and there was entire absence of any 

 deformation from superfluous liquid remaining in the junction rings. 

 One set took 47 days before the shrinkage caused the segments to 

 part, the support ring not having been raised. The ratio of length 

 to breadth of the equal segments two days before this occurred 

 was 1*5 :1, as compared to 1*17 :1 in a similar coloured column 

 of like dimensions, but without any cellulose thread, and dragged 

 apart by loading (see Fig. 28). 



The segment volumes of another set diminished during the first 

 fortnight from about 270 c.c. to 225 c.c, and the curved surfaces 

 from 145 to 120 scjuare centimetres. The calculated rates of air 

 transference obtained from the contraction curves, are given in 

 Table lY. ; the solution used contained 5 per cent ammonium oleate 

 and 50 per cent glycerin. 



Table IA'. 



