626 Profs. Rutherford and Barnes on the 



For the heating-coil the following readings Avere obtained : — 



Number of 

 Date. observations. Mean. 



November 9th 3 16*1 div. 



„ 10th 6 16-36 „ 



„ 15th 6 16-1 „ 



Average 16*19 



The ratio of heating-coil to radium gives 1*769. Taking 

 the coil as 65*2 ohms, and the current as "0068 ampere, the 

 total heating effect of the radium (Rd = 225) comes 106 gram- 

 calories per hour. 



Experiments with the leads gave for the radium on Nov. 

 19th as a mean of seven readings 11*94 divisions. These 

 readings were as follows : — 



Time. Scale. 



11.30 . . ... . 11-8 div. 



12.30 11*7 ,, 



1.30 12-0 ,. 



2.30 12*7 „ 



3.30 11/2 „ 



4.31 13-4 „ 



5.30 10-8 „ 



Using the heating-coil, the following readings were obtained 

 on Nov. 21st, the current remaining as before : — 

 Time. Scale. 



2.00 20*5 div. 



3.00 20*55 „ 



4.05 20-65 „ 



5.00 20-5 „ 



This gives 20*6 as the average. The ratio of 20*6 to 11*94 

 comes 1*725, and the heat emission of the pure radium 

 comes 108 gram-calories per hour. This showed us con- 

 clusively that no appreciable increase in heating effect was 

 brought about by absorbing the 7 rays. Had Paschen's 

 results been correct, an increase of at least 50 per cent, should 

 have been observed. 



We decided to verify these results by making slightly 

 larger lead cylinders. These were 5 cm. long and gave an 

 absorbing mass 11 mm. thick (diameter 3 cm.). For the 

 radium we obtained the following readings: — 



Number of 

 Date. observations. Mean. 



November 30th .... 3 12*5 div. 



December 1st ... . 6 12-33 



This gives an average of 12*42. 



55 



