tS eee 
W. Hallock—Smee Battery and Galvanic Polarization. 279 
wise the abbreviations are to be understood as in Table L 
Table III gives the polarization as it increases with the increase 
of the force of the primary battery from E=1-00 D. to H=4 
Planation. In all cases the force of the Daniell battery was 
taken as the unit of electromotive force. 
7. CONCLUSIONS. 
Although, as is well-known, the force of polarization in gen- 
eral varies according to the chemical affinities of the elements 
or radicals separated, still we cannot, yet at least, calculate the 
electromotive force of polarization from the thermal equivalents 
ot the reactions, because we do not know which of the reactions, 
Primary or secondary, should be taken account of, nor do we 
know their thermal equivalents. Table I seems to establish 
what has just been said; in most cases the calculated value is 
much smaller than the observed one, and the latter is not a 
true: maximum value, but only the largest attainable with two 
or three Bunsens respectively, in the polarizing circuit. Espe- 
Gially in the case of H,SO, is the difference great, and in fact, 
if its polarization were only P=1°36 D., as calculated one ought 
to get a good evolution of gas with two Daniell cells, which, on 
electrode, even when the latter remains chemically unaffected. 
Exner* ublished a series of experiments to prove that the 
Clectromotive force of polarization keeps equal to that of the 
Primary battery, when the latter is increased from zero upward, 
Until it reaches the point where the evolution of gas becomes 
Visible, and that from this point it (the polarization) remains 
Constant, no matter how much we increase the force of the 
oney battery. This result is contradicted by those given in 
ables I and IfI, inasmuch as with two Bunsens =38°4 D., the 
Evolution of gas was very easily visible.t Exner’s results are 
Mm so far in harmony with the theory of the conservation of 
energy as that no one will contend that a weaker electromotive 
force can overcome a stronger; but Helmholtz} has shown for 
* F. Exner, Wi ’ 
‘ wale ele “fables f apd HI only confirm the previous ideas regard 
ing the dependence of the polarization upon the density of the current upon the 
Surface of the electrode. ‘ng. Phil 
us Helmholtz, Pogg. Ann., el, p. 483, 1873; compare also F. ores oeny 
igh 1 P- 142, 1876; A. Bartoli, Nuovo Cim. Ill, iv, p. 92. 1878, III, v, p. “'™ 
