284 Electro-Magnetic Experiments. 
flaws but must have their particles in crystalline repose in order to 
act unequivocally. It also appears that when one part of a wire has 
been annealed and the other not, the two portions have different ca- 
pacities for caloric and act hike two different metals soldered togeth- 
er at the point of difference. Drawn, hammered or rolled metals 
therefore give equivocal results. | 
I find by my experiments that the metals give generally positive 
or negative results according to their relation to oxygen ; the less ox- 
idable metals being positive, and the more oxidable ones negative. 
Gold, which Prof. Emmet is surprised to find, by his experiments, on 
the negative side appears in my experiments on the positive side and 
that whether it has been annealed or not. It is to be regretted that 
experimenters in these interesting subjects do not give us more of 
the circumstances of their manipulation to enable us:to judge of their 
conclusions. I apprehend that some of Prof. Emmet’s very inter- 
esting experiments have been made equivocal by some of the circum- 
stances so liable to make them so; and | am not quite sure that my 
own may not be corrected by future investigation. I have howev- 
er detailed some of the circumstances to enable other persons to 
judge of them. The following is the result of my best observations. 
Positive metals in which the current of electricity from one portion 
of metal to the other proceeds from the heated portion in coincidence 
with the caloric. Deviation of the needle in 4 seconds, 
By hand heat, from 56° to 95°. By boiling heat, from 56° to 212°. 
Antimony, - +8° ? - - - +3829? 
Silver, - - +4 - - - +16 
Copper, - - +2 - - - - +8 
Gold, = - +14 - - ~ + 6 
Lead, - - +0 - - - - +0 
My experiment on antimony is questionable as to the degree, be- 
cause I could not fashion this refractory metal into the desired form. 
Lead is sometimes null and sometimes variable. 
Negative Metals, in which the current of electricity from one por- 
tion of metal to the other, proceeds from the colder in opposition to 
the caloric. Deviation of the needle in 4 seconds, 
By hand heat, from 56° to 95°. —- By boiling heat, from 56° to 212° 
Bismuth, a) ite ELS - 2 a Cynics 
lron, - - - '4 - - - - 16 
Zinc, - - aie . = “ Nias fl 
Tiny, &)y/-0 eee imperceptible: Hl <ing f=\y mite os 
Lead, - - a (0) . eh ef Rng) 
