W. Hallock—Smee Battery and Galwanic Polarization. 271 
it is evident that this method simply substitutes evolved hydro- 
gen for any other gases which may happen to be dissolved 
in the acid, and it is just the hydrogen which it is necessary 
to Temove, since to its presence is generally ascribed the 
diminution of the electromotive force below that obtained 
BD) electrometer or by the compensation method (about 
In this research the following method was used to obtain a 
cell free from dissolve gases. 
the cell used. Its force, when freshly filled with 5 per cent 
H.SO,, through a circuit of 150,000 S. E. was found E=1-07 D. 
It was then closed in a circuit of only 0-2 S. HE. external resist- 
ance containing a tangent compass, and its force at the expira- 
hon of the first minute determined to E=0-71 D. after 20 min. 
‘o H=0-06 D. and after 70 min. to E=0-03 D. These small 
Values, although they agree well with those obtained by 
Fromme,* can only be considered as approximations owing to 
the difficulty of accurately determining the internal resistance 
of inconstant cells. The cell was then left short-circuited for 
ours inorder to let the evolved hydrogen drive out the 
other gases as completely as possible; at the expiration of this 
time its force through a circuit of 150,000 S. E. was found quite 
onstant E=0-69 D. In order now to drive out the hydrogen, 
the flask was placed over a burner and kept at a sharp boil for 
0 min., the steam and gas passing off through a long nar- 
‘ow tube in the cork. A layer of petroleum about 1 deep 
Was poured over the acid while boiling, to assist in keeping 
gases from redissolving in the acid. The flask was then sealed 
shut with hard wax and cooled. Its force 5 sec. after being 
d in a circuit of 150,000 8. E. a ren E=0°86 D. 
When its force in a circuit o 
‘during the first minutes, it rose gradually, ho 
became constant after six minutes at EH=0-70 D. 
boiled and covered with petroleum and sealed as b 
force through 150,000 S. E. was found E=1-01 D. 
ovever, in 4 min. to E=0'88 D. in 25 min. to E=0°83 D., 
nd in 24 hours to H=0-78 D. 
"Thus it would seem that the value E=0-70 D. represen 
that force which is active when the liquid immediately aroun 
* 0. Fromme, Ll. ec. 
