FOREIGN CORRESPONDENCE. 



107 



a salt which silver is very apt to form, and which is one of the 

 most plentiful of the silver-ores. Small particles of it are constantly 

 washed down by probably most rivers, and carried to the sea, where it 

 is dissolved by the salt-water. 



Copper has just been discovered in the water of the !Mediterranean 

 by Septimus Piesse, whose remarks have been published by our 

 Parisian contemporary, Cosmos. To the sides of a steam-vessel going from 

 Marseilles to Corsica, the author attached bags filled with nails and 

 iron-filings. Iron having the power of displacing copper from its com- 

 binations, the iron nails and filings were found on examination to have 

 extracted from the water a notable quantity of copper, which adhered 

 to the nails and iron-filings. Certain soluble salts of copper, such as 

 the sulphate for instance, which are not easily decomposed by 

 natural agents, are probably carried down to the sea by rivers, together 

 with insoluble particles, such as sulphide of copper, which, by long 

 contact with sea- water, would transform itself into sulphate or chloride 

 of copper, and be dissolved. M. Septimus Piesse has gone so far as to 

 attribute the blue and green colours of certain parts of the ocean to salts 

 of copper. But this was a rash step to take, and it would have been 

 more reasonable had the author contented himself with stating simply 

 the discovery of a small quantity of copper in sea-water — a discovery 

 not devoid of interest — rather than attribute to this source the colora- 

 tion of the waters of the ocean, which may be due to a thousand more 

 likely causes. 



lu searching for copper by the above means, gold, if any were in 

 solution in the sea, would certainly have been found. N^one of this 

 most precious metal has ever been discovered in sea- water ; and why ? 

 The reason is obvious — salts of gold are very easily decomposed; the 

 least particle of organic matter decomposes the soluble ones, and pre- 

 cipitates their gold. Hence, when gold is met with in nature, it is 

 always in the metallic state. It is impossible, therefore, that it can 

 ever be found in sea- water, although no doubt exists as to a million or 

 two sterling being washed down now and then by the various rivers, 

 and swept into the sea in different parts of the world. If we wish to 

 discover maritime gold we must look for it in the sand of the sea-beaten 

 shores. 



This reminds us that we have just received a sample of sand said to 

 be auriferous, and recently imported by some speculators from the 



