PENETRATION OF X-RAYS. 



TABLE 43, continued. Continuation of the preceding. 



7 1 



In the first part of table 42 the alternations are promiscuous, but 

 they fail but once in 8 observations (curve 71 ; failure at*). In the 

 second part, where the coronas are nearly measurable, there is no 

 failure (curve 70). The third part shows that exposures of i minute 

 are not sufficient to bring out the phenomenon. 



NUCLEATION DUE TO RAYS PENETRATING FROM A DISTANCE OR 



THROUGH DENSE MEDIA. 



57. Effect of distance of the X-ray bulb from the free wooden fog: 

 Chamber. The probability of a residual effect in case where the X-ray 

 bulb is moved to a considerable distance from the fog chamber is sug- 

 gested by many of the above results. It is worked out in detail in 

 table 44, where the condensations described were all made at the press- 

 ure difference corresponding to the fog limit of dust-free nonenergized 

 air, and without cutting off the radiations. There is thus no decay. 

 Nevertheless, the results are, as usual, disappointingly irregular, the 

 first datum of each pair of results being low, the second high. Perio- 

 dicity therefore occurs in spite of the wet-sponge tube added to the 

 filter. The observed variation of results is moreover impossible in 

 relation to distance, even though the data for inferior and superior 

 coronas are apparently consistent in both outgoing curves. Again, in 



