192 Profs. Richardson and Cooke on the Heat developed 



The numbers in the various columns represent the same 

 quantities as the corresponding columns in the previous table. 

 In the last five sets of experiments the precise treatment of 

 the grid was not recorded, but before the experiments 

 Nos. 6, 8, and 10 the filament was exposed for varying 

 lengths of time to hydrogen by electrolysis of sulphuric acid. 

 A glance at the last column will show that the agreement of 

 the results among one another is not so good as in the case 

 with the experiment when the strip had been exposed to 

 nascent oxygen in nitric acid. We have not yet been able 

 to trace the cause of this disagreement with certainty. The 

 mean of all the ten values gives 4*85 volts for the effect. 

 It will be noticed that the three last voltages are considerably 

 higher than any of the others. If these are rejected, the 

 mean is brought down to 4*49. There does not, however, 

 seem to be any compelling reason for rejecting them, as the 

 individual observations look satisfactory, and so far as we are 

 able to judge, they were made under conditions similar to 

 those which held while the other observations were being- 

 made. 



Taking a general view of the whole results which have 

 been obtained so far, it would seem that saturation of the 

 filament with hydrogen reduces the magnitude of the effect 

 nearly one volt from the value obtained when it has been 

 saturated with oxygen. 



§ 10. Platinum Wire Grid. 

 As has been stated above, experiments were also made 

 with a grid wound with platinum wire of '012 cm. diameter. 

 The results of these experiments are exhibited in the follow- 

 ing table : — 









*j • .• 









^ 



ZM 



o> ft 



s & 



Interval 



(seconds). 



"o 



> 



R 

 Ph 



o 



R 



Saturation cm 

 rent XlO 5 . 



o s 



o 



oo O 



W 



d ° 



"1 &> 



— S3 



6 X 



Final correcte 

 value (volts). 



I- 



£0 



304 



5-0 '(1)18-28 



622 



11-8 



0-6 



5-89 



2. 



30 



3-00 



5-0 '(1)18-45 



5-95 



11-4 



0-6 



5-62 



t ■ 

 4. 



30 



2-98 



5-0 (1)22-57 



1 



6-69 



11-72 



06 



6-36 



120 



2-98 



5-0 '(1)22-57 

 1 



5-69 



11-72 



06 



5-36 



