fHE GEOLOGIST. 
longing to one principle, of electricity, magnetism, and galvanism have emanated 
in unbroken succession from the concatenation of circumstances and the persever- 
ing and ingenious experimental researches by which the elucidation of these 
recondite phenomena have been effected 
The present tendency of chemistry is towards a reduction of the number of 
those bodies hitherto considered as elementary ; rapid, indeed, has been the growth 
of organic chemistry through the labours of Hoffmann, Berthelot, and others. 
The important power of synthesis has grown with this growth. Since Wohler, in 
1828, succeeded in artificially producing " urea," Kolbe has similarly, by the com- 
bination of inorganic elements, produced acetic acid ; while Berthelot has formed 
glycerine ; of the bases of vegetable oils and fats he has also formed grape-sugar, 
and has realised the synthetic preparation of camphor. An important series of 
alcohols and derivatives, as extensive a series of ethers, including those which 
give their flavour to our choicest fruits, together -with other important organic 
bodies, are now capable of artificial formation from their elements, and the old 
barrier dividing organic from inorganic bodies is broken down. 
Since Niepce, Herschell, Fox Talbot, and Daguerre laid the foundations of 
photography, year by year some improvement is made — some advance achieved 
in this most subtle application of combined discoveries in photicity, electricity, 
chemistry, and magnetism. 
(To be coniinued.) 
REVIEWS. 
The Mining and Statistic Magazine. By Thomas McElrath. No. LXII. August, 
1858. New York : George M. Newton. 
This number of a very useful and instructive magazine has reached us from the 
other side of the Atlantic, and has alForded us much pleasure in the perusal. Its 
articles are generally of a practical character, many, of course, being of local 
v.alue ; but there are others ■which will be read everywhere with interest. Such 
is the first part of a very interesting essay, by S. P. Leeds, upon the influence 
which water holds in mineral veins. 
This inquiry is a very important one, if it be true, as it generally stated, that 
dry veins arc barren, and that with the abundance of springs of water hey become 
more and more prolific. The elucidation of the present question would go far, in 
connexion with other inquiries, to determine the principles which govern the 
formation of metallic veins, and, as the author of this essay justly observes, such 
knowledge would be of inestimable value to the miner, as it would teach him to 
discover upon an early examination of a vein, whether it would be a productive or 
a barren one. 
Certain laws or principles must govern the formation of all mineral veins, which 
cannot be the result of fortuitous circumstances ; the circumstances attendant 
upon them are too uniform in character to be the effect of casualties ; and the 
forces which have caused the deposition to their metallic contents arc still in 
active operation. Nature, except in isolated instances, ever produces the greatest 
results from minute materials and long-continued action. 
If the metallic deposition in those veins which have been allowed to refill with 
water is plainly perceptible in the brief period of one or two centuries, it is 
evident that much of the character and quality of a vein depends upon the water 
circulating through it ; which not only merely acts as a solvent, but brings into 
activity electric, chemical, and other subtile forces essential for the concentration 
or deposition of metallic particles. 
