

284 Electro-Magnetic Experiments. 



flaws but must have their particles in crystalline repose in order to 



act unequivocally. 



of 



for caloric and act like two different 



dm 



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 I 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° ? - - - +32° ? 



Silver, - - +4 - - - +16 



Copper, - +2 - - - - + 8 



Gold, - - +1J ... +6 



Lead, * - +0- - - - -}- o 



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, 



JVegative 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, - - 11° - - - - 44° 



Iron, - 4 



Zinc, 1 



16 

 4 



Tin, - - Imperceptible. - 0£ 



Lead, 







