7 



VAPOR NUCLEI AND IONS. 



while there is evidence of slight improvement, irregularities are at times 

 increased. The final data in the table relate to the effects of X-rays from 

 short distances (D = 20 cm. to anticathode), and the peculiar feature here 

 is the steepness of the line as compared with earlier results. The reason 

 is in part due to the admission here of dp p-p 3 instead of the observed 

 dp as heretofore, the effect being to displace upper observations rela- 

 tively more to the left. It is already quite clear, however, that neither 

 for X-air nor for ordinary air have the earlier data been much improved. 

 The highest corona attained in both cases is again the green-blue-purple 

 type. 



Table 23. Atmospheric air. Two observations daily, 

 exhaustion. op = p - p 3 . Aug. diameter 5/30 nearly. 

 250 cm. from light. 



Water nuclei removed by low 

 Fog chamber 40 cm. from eye, 



50. Observations, continued. In the experiments of table 22 much 

 difficulty was experienced with the apparatus, as the use of oil with the 

 large stopcock was often liable to show itself in the blurred walls of the 

 fog chamber whenever this was wetted with water. It is usually suffi- 

 cient to heat these walls gently, in order to evaporate the suspicion of 



