SUPPLEMENTARY NOTES. 
617 
the operation of a general law. It is worthy of remark that 
many of the large veins of hocmatite, and other varieties of the 
oxide of iron found in Cornwall, have nearly a N. &S. bearing. 
I am not prepared to say whether there are any exceptions, or 
not; but it is curious to find decided iron veins nearly coin- 
cident with the mean magnetic meridian.” 
M. Becquerel has recently made a most important application 
of some electro-chemical apparatus, to the immediate reduction 
of the ores of silver, lead, and copper, without the intervention of 
mercury, and is now occupied with further researches on the 
extraction of metals from their respective ores. L’Institut. 
March 21, 1836. Phil. Mag. February, 1837. 
The practical results of these researches are noticed in the 
following terms by Mr. Wheatstone, in a letter I have recently 
received from him upon this subject. “ The value of Mr. Fox’s 
interesting experiments consists in the exact analogy they bear 
to the circumstances which actually take place in mineral veins; 
sfill more important are the long-continued researches of M. 
Becquerel, on the permanent action of feeble currents in ef- 
fecting chemical combinations and decompositions; a very 
full account of these instructive experiments has recently been 
published in the the third part of Taylor’s Scientific Me- 
moirs, and deserves the attention of every geologist who desires 
to penetrate into the mysteries of mineral formations. Neither 
are these investigations without practical value; M. Becquerel 
has recently shown a mode by which the precious metals may 
be separated from their ores, in a perfectly pure state, without 
the aid of mercury ; and we understand that the process is now 
actually working in some of the mining establishments of 
France. The electro-chemical apparatus for this purpose, con- 
sists simply of iron, a concentrated solution of sea salt, and the 
ore of the metal properly prepared. Thus that mighty agent, 
which nature has hitherto exclusively employed in her exten- 
sive laboratory, is beginning to bo the obedient servant of man ; 
and it requires not the tongue of a prophet to foretel that the 
voltaic pile will hereafter create as great a revolution in our 
chemical manufactories, as the steam-engine has already efiected 
in the mechanical arts.” 
