Faraday as a Discoverer. 183 
of the like kind. And I know I have never lost by it. I would 
not say all this to you did I not esteem you as a true philosopher 
and friend.* 
“Yours, very truly, M. Farapay.” 
| Identity of Electricities: First Researches on Electro-Chemistry, 
Thave already once used the word “ discomfort” in reference 
to the occasional state of Faraday’s mind when experimenting. 
It was to him a discomfort to reason upon data which admitted 
of doubt. He hated what he called “doubtful knowledge,” 
and ever tended either to transfer it into the region of undoubt- 
ful knowledge, or of certain and definite ignorance. Pretence 
of all kinds, whether in life or philosophy, was hateful to him. 
He wished to know the reality of our nescience as well as of our 
science, “Be one thing or the other,” he seemed to say to an 
unproved hypothesis, “come out as a solid truth, or disappear 
asa convicted lie.” After making the great discovery which I 
have attempted to describe, a doubt seemed to beset him as re- 
gards the identity of electricities, ‘Isit right,” he seemed to 
ask, “to call this agency which I have discovered, electricity 
atall? Are there perfectly conclusive grounds for believing 
that the electricity of the machine, the pile, the gymnotus and 
rtpedo, magneto-electricity and thermo-electricity, are merely 
Herent manifestations of one and the same agent ?” To an- 
swer this question to his own satisfaction, he formally reviewed 
the knowledge of thatday. He added to it new experiments 
ot his own, and finally decided in favor of the “ Identity of 
Electricities.” His paper upon this subject was read before the 
Royal Society on the 10th and 17th of January, 1833. 
After he had proved to his own satisfaction the identity of 
electricities, he tried to compare them quantitatively together. 
The terms quantity and intensity, which Faraday constantly 
sed, need a word of explanation here, He might charge a 
single Leyden jar by twenty turns of his machine, or he might 
charge a battery of ten jars by the same number of turns. The 
quantity in both cases would be sensibly the same, but the in- 
nsity of the single jar would be the greatest, for here the elec- 
tricity would be less. diffused. Faraday first satisfied hi 
that the needle of his galvanometer was caused to swing through 
© same arc by the same quantity of machine electricity, 
Whether it was condensed in a small battery or diffused over a 
Dang Tay Would have been rejoiced to learn that, during its last meeting st 
coe; the British Association illustrated in a striking manner 
Which h describe i inci 
“ale men are never beyond healing. 
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