DISTANCE EFFECTS. 



83 



pressure (dp) being below the coronal fog limit of dust-free air. Hence 

 there are no complications from colloidal nuclei. In parts I and II of 

 the table the X-ray bulb was not inclosed in the windowed lead vessel 

 specified, whereas in part III this is the case; while in part IV a tin 

 plate has been placed over the window. 



Table 32. Distance effects due to X-rays. Fog chamber of glass with 2.5-inch gas 

 cock and 2-inch piping 12 inches long. X-ray, 7 cells. dp= 23.8 cm. 



I. Bulb not inclosed; meters 



D. 



o-5 

 6.0 



2.0 



5 



10 

 6 

 6 



! 



1- 



11 . 



Corona, n X 10 



.- 1 



wcg 

 cor 



w'BP 

 w'BP 



gy 



220 

 80 



75 



"5 

 120 



260 



dp = 20. 3 cm. 



II. Same; bulb not inclosed . 



90 



IOO 



42 

 42 

 13 

 13 

 15 

 28 



75 



70 



100 



105 



22.7 ; X-ray bulb in lead case 1 with window 7.5 cm. in diameter. 



III. Window open 



Lid off . 



22 



27 



85 

 135 

 135 

 135 



Same. Tin plate 1 over window. 



IV. Tin window 



6.5 



40 



99 



1 Lead sheet 0.12 cm. thick; tin plate 0.03 cm. thick. 



