NOTES AND QUERIES. 



349 



elements has been effected between the chloride of sodium and the car- 

 bonate of lime, giving rise to the formation of chloride of calcium and car- 

 bonate of soda. It has been long suspected that the natural production of 

 carbonate of soda was dependent on the presence of carbonate of lime, and 

 was brought about somewhat in this way ; but what the conditions are under 

 which the separation of the carbonate of soda from the chloride of calcium 

 is effected, without allowing the former to exert its ordinary converse 

 action upon the lime-salt and reproducing carbonate of lime, is a question 

 that would form a very interesting subject of scientific inquiry. This 

 is, I believe, the first time that the natural production of alkali from sea- 

 water itself, without organic agency, has been observed. 



It is hardly probable that the production of carbonate of soda in this 

 way is limited to a few miles' distance from Aden. As the shore is so 

 very similar along the whole 1125 miles which form the south-east coast of 

 Arabia, there is a reasonable expectation of finding it at many places else- 

 where ; and an article so much in request, so easily procured, and with 

 water-carriage close at hand, might yield a fair amount of profit to an en- 

 terprising shipper who should collect or purchase it upon the spot. 



Lake Superioe Silvek. — The silver found at Lake Superior is native, 

 and is the most extraordinary metallurgical paradox yet discovered, in 

 which nature has shown that she can completely surpass art. It is found 

 in large quantities in the native copper mines of that district. The com- 

 binations of the silver with the copper present most varied forms ; in some 

 instances the native silver is found running through a mass of native cop- 

 per in veins of varied thickness, like veins in marble ; at other times it is 

 found attached to masses of copper, in many beautiful floriated forms of a 

 large size and sometimes resembling the stumps of old trees, and fre- 

 quently covering the whole surface of a mass of copper on all its sides to 

 a considerable thickness, and presenting most beautiful forms in cubes, 

 prisms, and four-sided pyramids, which appear as though the whole mass 

 of copper had been thickly electrotyped with the precious metal. Its 

 varied forms and its extreme purity, although in conjunction with the 

 copper, renders it a subject of the greatest curiosity, both metals having 

 been, some think, subjected to a heat that must have been equal to a re- 

 finer's smelting-heat, and yet the metals are each found in perfect purity. 

 In all the mass of copper of this vast district, silver is associated with it 

 to a greater or less degree, but not in sufficient quantity to pay for its se- 

 paration. The rock in which the silver of this district most abounds is an 

 amygdaloidal trap of a very compact nature. The miners of this district 

 for many years considered the native silver as a perquisite, — as they used 

 to say they were employed to mine for copper and not for silver ; there- 

 fore the proprietors rarely used to get the silver, but the miners always 

 had an abundance. This state of things now no longer exists, and the 

 proprietors get a large share of this valuable production. 



In a contribution to the 'Washoe Times,' Mr. J. B. Truckee states that 

 he had the most valuable collection from the Superior mines in Europe, 

 which he was solicited by the commissioners for mines and minerals to 

 place in the Paris Exhibition as an illustration of the productions of the 

 mines of Lake Superior, they undertaking to return the collection intact 

 when the Exhibition closed ; but at the time when he looked for its return, 

 he was waited upon by two gentlemen, who, came from the Emperor of 

 France, to request that the collection might remain at the School of Mines 

 in Paris. As Mr. Truckee considered this school the first of its class, 

 he consented to his collection remaining there. 



In this collection there are crystals of pure native copper in clusters of 

 perfect cubes, to which are attached floriated native silver. 



