154 PROCEEDINGS OF THE AMERICAN ACADEMY 



best, and we can thus apply it to the Daniell cell. The following 

 quantities are mostly taken from Kohlrausch. 



The quantity c has been found by various observers, and Kohl- 

 rausch* gives the mean value as .009421 for water according to his 

 units (nig., mm., second system). Therefore for hydrogen it is 

 .001047. 



The quantity // can be observed directly by short-circuiting the 

 battery, or can be found from experiments like those of Favre and 

 Silbermann. 



The electro-motive force E can be made to depend either upon the 

 absolute measure of resistance, or can be determined, as Thomson has 

 done, in electro-static units. In electro-magnetic units it is 



Absolute Measure 

 Siemens. Ohms. according to my 



Determination. 



After Waltenhofen 11.43 10.90 10.80 X 10 10 



" Kohlrauschf H-71 11.17 11.07 X 10 10 



After Favre, 1 equivalent of zinc develops in the Daniell cell 



23993 heat units ; 



J E_ 



9 c II g 



On the mg., mm., second system, we have E ' = 10.935 X 10 10 , 

 c = .001047, H= 23993, g = 9800.5 at Baltimore. 



.-. — = 4441 60 mm - = 444.2 meters. 

 9 



Using Kohlrausch's value for absolute resistance, he finds 45G.5, 

 which is much more in error than that from my determination. I do 

 not give the calculation from the Grove battery, because the Grove 

 battery is not reversible, and action takes place in it even when no 

 current flows. 



Thomson finds the difference of potential between the poles of a 

 Daniell cell in electro-static measure to be .00374 on the cm., grm., 

 second system, t ' Using the ratio 29,900 000 000 cm> per second, as I 

 have recently found, but not yet published, we have 111 800 000 on 

 the electro-magnetic system or 11.18 X 10 10 on the mm., mg., second 

 system. This gives 



— = 474.3 meters. 



>J 



* Pogg. Ann., cxlix. 179. 



t Given by Kolilniuscli, Pogg. Ann., cxlix. 182. 



J Thomson, Papers on Electrostatics and Magnetism, p. 210. 



