494 



Dr. C. H. I)n 



>er on the 



th 



No. of ohms in 

 main circuit. 



4115 



No. of ohms 

 between PQ. 



2110 



Deflection on 

 scale in centim. 



44-64 



If be deflection of needle, tan 20 = 44-64-h 345-44 = '1292, 

 whence 20 = 7° 21' 45" and = 3° 40' 52". Corrected for 

 torsion, 0=3° 42' 5" and tan<9 = '06469; whence if C = 

 current in absolute measure, C = -004618 x -1742 x -06469. 

 The resistance between the points P, Q = 2110x 10 9 in abso- 

 lute units; therefore E.M.F. of cell = CR = 2110 x 10 9 x 

 •004618 x -1742 x -06469 = 1-098 x 10 8 , or 1 -098 volt. 



Here and throughout the old value of the ohm is taken. 



After the results were reduced another correction was 

 applied for the effect of the platinum wires to the end of 

 which the electrometer-wires were joined, and which, being 

 in the battery-circuit, caused the potential-readings to be 

 higher than would have been the case if the electrometer had 

 been joined directly to the electrodes. Their resistance at 

 16°, as determined by the Wheatstone-bridge, was '22 ohm ; 

 and from Siemens' formula, 



r /= r o {-03969T^+-002164T--2413}. 



The resistance at 40° is thus *253 ohm, and at 80° is 

 •283 ohm. 



The following table gives the reduced observations for 40° 

 and 80°, and the curve in the accompanying figure shows the 

 relation between them. The observations for 60° and 100° 

 are not given, as they would only serve to confuse the figure. 

 The current-values are in amperes, and the differences of 

 potential in volts. 



Teinperat 



ire 40° C. 



Teinperat 



ire SiPC. 



Current. 



Difference of 



Current. 



Difference of 





potential. 





potential. 



0-(W 



2-75 



062 



2-40 



. 0-84 



2-92 



0-79 



254 



1-09 



3-08 



1-02 



2-64 



1-39 



331 



1 22 



2-87 



1-85 



359 



1 47 



311 



231 



n-ij 



I'M) 



3-29 



267 



414 



2"22 



357 



304 



442 



2-57 



385 



338 



4-70 



289 



401 



3-78 



5'0(> 



3-21 



424 



408 



531 



407 



4-80 



425 



•V47 



4 <;s 



f>-44 



