1918] 



on Studies on Liquid Films 



375 



column, the horizontal junction films being segments of circles, 

 while the inclined films took the form of rectangles with their short 

 sides slightly convex. The data for this formation were : Xozzle, 

 5 cm. diameter : air current, 1:^0 c.c. per minute, with an interval of 

 15 seconds between successive drops. Each element of the column 

 thus had a volume of 82i c.c. 



Three columns will also coalesce from top to bottom, twining 

 round each other like the spiral strands of a rope. The plane 

 films linking the bubble segments are then truncated sectors of 

 circles. 



A complex of four interpenetrating vertical columns is shown in 

 Figs. 11 and 12. This may be considered as built up by a succession 

 of horizontal pairs of bubbles, each pair being at right angles to the 

 adjacent pairs above and below. The symmetrical pairs of 

 horizontal plane films v^hich link them are circular quadrants with 

 their points in contact, and of course are alternately at 

 right angles. 



Between each member of the alternate horizontal 

 pairs of bubbles there are vertical films which are 

 diamond-shaped, and joined at their apices with 

 their planes alternately at right angles along the 

 axis of the cluster. The resulting appearance is very 

 regular. One example of this formation was produced 

 by a nozzle of 5 cm. diameter, with an air current of 

 400 c.c. a minute, and an interval of 4 to 5 seconds 

 between the drops. 



A still more complex but perfectly regular quadruple 

 column has the simple string of diamond-shaped films 

 replaced by alternate hexagons and squares of which 

 only the hexagons are vertical. An isometric view of 

 this part of the arrangement is shown in Fig. 13. 

 The common edges of adjacent squares and hexagons are 

 horizontal, and alternate squares are equally inclined in 

 opposite directions to the axis of the complex column. 

 The complete configuration is shown in Figs. 14 and 15 

 (two perpendicular views) ; the outlines are further dis- 

 played in Fig. 16. 



Multiple columns of a higher order were obtained by 

 lessening the time-interval between the drops. The 

 excess, liquid thus supplied tended to distort the cluster. 

 This was avoided by employing a long nozzle within Fig. 13. 

 which the network of bubbles was formed and supported 

 until the excess liquid drained away. The cluster was then expanded 

 clear of the nozzle, and remained stable and undistorted. As many 

 as seven or more interlaced vertical columns were obtained in this 

 manner. The centre bubbles of the cluster were of course completely 

 enclosed, and hence had no curved surfaces, but formed instead a 

 Vol. XXII. (Xo. 112) 2d 



