730 



of emanation present extracted by boiling. If Fango was treated 

 thus, vevy strong ionisations could again be observed. I shall not 

 mention all the values obtained according to the various methods; 



30 



25 



»1 J2 la 17 20 



Number of the samples. 



let it suffice to mention here, that also in this case the figures 

 pointed to a radio-activity not exceeding that of 10 -^^ grammes of 

 radium pro gramme. 



Finally I will mention one very important experiment taken with 

 the various samples of boring (cf. Part I). From the "conclusions" 

 which Dr. Blaauw has derived from my data one may notice how 

 he could entirely account for the course of the ladio-activity in the 

 series of the borings. I thought it desirable also to appl}' the "direct 

 method" to these samples of boring to wind up my researches. The 

 result will be found represented graphically in curve II of Fig. 2, 

 whereas curve I fixes the values mentioned in table 1 according 

 to the emanation method. The conformity in the course will 

 strike one: with the exception in the case of N". 12 there occur 

 in both curves corresponding fallings and risings. As not only the 

 quantity of radium influences the values of the "direct method" 



