Solution of Atmospheric Nitrogen and Oxygen by Water. 387 



photographing each bubble and the scale in close proximity 

 to each other, through the water-jacket, by providing a scale 

 ruled on thin tracing-paper, and cementing this to the inner 

 tube with Canada balsam, This scale was almost trans- 

 parent, and the image of the bubble was orthographical^ 

 projected on to it by means of a beam of parallel light from 

 an arc lamp. The camera was focussed sharply on the scale, 

 •and the shutter was released just as the bubble passed behind 

 the scale, so that on the negative the scale lines were 

 superimposed upon the image of the bubble. 



These negatives were measured by means of a travelling 

 microscope, and the measurements referred to the paper 

 scale, the errors of which were determined bv means of 

 a standard scale both before and after use. The length 

 ■of each bubble, when at rest, was measured with a mirror 

 scale, which was also compared with the standard scale, and 

 the area of the bubble was calculated from the formula 

 <deduced in the first part of this communication. The results 

 of the measurements are given in Tables I. and II. 



Table I. 

 Measurements of Bubbles of Different Volumes, 



Temperature. 



Volume. 



Len 



gth in Motion. 



Length at rest. 



25° 0. 



15-0 c.c. 





15-98 cm. 



1325 cm. 



'» 



12-5 „ 





13-61 „ 



11-10 „ 



,, 



100 „ 





ll'll „ 



8-85 „ 



•5 



7'5 „ 



• 



8-48 „ 



6-70 ., 



55 



5-0 „ 





590 „ 



4-45 „ 



Table II. 

 Calculation of Areas. 



Diameter. 



Volume. External. Internal. Thickness of wall. Area. 



15-0 c.c. 1-20 cm. 1*099 cm. -050 cm. 56'33 



12-5 „ „ 1-091 „ -055 „ 47-58 



10-0 „ „ 1-086 „ -057 „ 38-85 



7-5 „ „ 1-078 „ -061 „ 29-63 



5-0 „ „ 1-058 „ -071 „ 20-52 



202 



