278 TlMEHRI. 
In the search for metallic veins, it might be sup- 
posed that a knowledge of their origin might be use- 
ful, but while we possess a general acquaintance with 
their modes of occurrence, much uncertainty prevails as 
to the causes which have produced them. While some 
veins are doubtless due to the influence of igneous action, 
others have as certainly resulted from aqueous agency, 
while others again may be attributed to the combined 
action of both causes, while in every instance there has 
almost certainly been a pronounced manifestation of 
electrical forces. It is probable that electricity has 
formed a more important element than is generally sus- 
pected, and this may more readily be believed when it is 
recollected that one of our most imminent geologists was 
prepared to find the whole series of volcanic phenomena 
referable to the evolution of heat by electricity in the 
interior of the earth. 
Attention was first directed to the part played 
by electricity in the formation of metallic veins, by 
Mr. R. W. Fox and M. Becquerel, the latter of 
whom " imitated nature, and produced by slow electric 
action, the sulphides of silver, copper, lead and tin in 
the most perfect and beautiful crystalline forms," and in 
recent years a good deal of attention has been given to 
the subject. The result of investigations in Australia 
tends to prove that while electric currents have evidently 
been concerned in the formation of many auriferous 
veins, the same agency also exerts a powerful influence 
upon the distribution of gold in the alluvial drifts, many 
of the phenomena in connection with such deposits being 
incomprehensible on any known action of chemical or 
mechanical agencies, but perfectly explainable if referred 
