m 



THE GEOLOGIS*. 



lon'^iDg to one principle, of electricity, magnetism, and galvanism have emanated 

 in unbroken succession from the concatenation of circumstances and the persever- 

 iuf and ingenious experimental researches by which the elucidation of these 

 recondite phenomena have been effected 



The present tendency of chemistry is tovrards 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 continued.) 



EEVIEWS. 



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 afforded us much pleasure in the perusal. Its 

 articles are generally of a practical character, many, of course, being of local 

 value ; 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 are 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 are still in 

 active operation. Nature, except in isolated instances, ever produces the greatest 

 results from minuic materials and long-continued action. 



If the metallic deposition in those veins which have been allowed to Tefill 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. 



