PENETRATION OF X-RAYS. 



TABLE 52. Distance effect of X-rays. Glass fog chamber. 8p = 22 cm. (fog limit 

 of air). No lead casket. Walls, 0.3 cm. Bottom i cm. thick. 



* Faint and small, due to dust-free air. 



TABLE 53. Distance effect of X-rays. 5^ = 22 cm. Lead plate 0.14 cm. thick. 



53 = o, but always tested. 



Part I. Cylindrical fog chamber, without casket. 



Part II. Cylindrical fog chamber, lead-cased, with tubular end of lead 50 cm. long. 



(Fig. 42.) 



Part III. Lead-cased fog chamber as before. Penetration through tinned iron 



plates 0.05 cm. thick. 



* Double glass envelope. 



