384 Correspondence of J. Nickles. 
roasting. An experiment has been made on more than 30,000 
kilograms of ores from Mexico and different parts of the globe. 
The great solvent which he uses is common salt. We will give 
further details in our next communication. 
ciently energetic to decompose water. Compared with a Bun- 
sen’s couple of the same size, it has about one-fourth the inten- 
lass is inserted enclosing a cylinder of copper; after having 
lled all the interstices of the barrel and of the tube with pow- 
dered glass, the whole is placed horizontally in a furnace, and the 
barrel and the copper cylinder are put in communication with @p-" 
paratus for collecting the electricity. : 
hese currents are not thermo-electric ; for if the glass 1s" 
moved, a galvanometer put in communication with the iron and 
copper rests at zero. : 
M. Becquerel considers it probable, in view of these pyro-elec- 
tric currents, that terrestrial electric currents exist in contact h 
or near the junction of the solid part of the globe with the part 
in fusion, where there may be solid conducting substances Pal 
tially empasted in the melted silicates in the manner of a pyt 
electric couple. 
On the electricity produced during the evaporation of soetorg 
: ‘of M. 
salt. 
