RECENT PROGSESS IN PHYSICS. 397 



le current was the same, it appears that the product of t and I re- 

 lains pretty nearly constant. It is — 



'or the current 10.53 : 



(2.) German silver, a t I z= 53.46 



(4.) German silver, 6..... t I =z 54.06 



for the current 14.30 : 



' (3.) German silver, a t I =z 28.18 



(5.) German silver, h tl = 28.11 



(7.) German silver, h tl z=z 27.40 



(9.) Platinum tl = 28.00 



Vor the current 18.32: 



(6.) German silver, 6 tl^=z 16.99 



(8.) German silver, c t I ■=. 17.12 



(10.) Platinum tl= 10.71 



' (12.) Copper tl= 18.08 



iFor the current 22.69: 



(11.) Iron tl = 10.84 



(13.) Copper tl = 11.60 



The equality of the values o^ t I for one and the same current is so 

 apparent that we may safely assume that the time of heating is in- 

 versely proportional to the resistance to conduction, or in other words, 

 that the heat produced in a given time is directly proportional to the 

 resistance to conduction, and independent upon other properties of the 

 metaU 



In order to find out how the production of heat depends on the force 

 'of the current, we must compare the experiments that were made with 

 the same wire, and with different currents ; from these it appears that 

 the value of s'-t is nearly constant for the same wire. The results are 

 as follows : 



For the German silver wire a : 



1 sH= 64.8 



2 sH=z 63.3 



3 sH = 61.3 



For the German silver wire b: 



4 s-t= 102.0 



5 s-t= 98.4 



6 sH= 96.7 



7 sH= 93.5 



For the platinum wire: 



9 sH = 113.5 



10 s-t=: 109.1 



For the copper v/ire : 



12 sH= 436.6 



13 5-^ = 429.9 



14 sH= 435.5 



15 sH = 414.2 



16 sH = 412,0 



By these experiments, therefore, it is demonstrated that: 



1. The production of heat is proportional to the resistance cf the wires 

 to conduction. 



