234 Miscellaneom Intelligence. 



4. Among the preparations which came to me from Paris to 

 Spain, to furnish the laboratory of the artillery there, were a 

 dozen bottles of fuming muriatic acid, which had been prepared 

 in the laboratory of the druggist, Charlard: all these bottles 

 contained mercury. I at first perceived it, from an amalgam of 

 tin and mercury being left on dissolving some tin in the acid ; 

 and afterwards I directly ascertained its presence by purifying 

 the acid in the usual manner, and examining the residuum left; 

 it contained mercury mixed with oxide of iron. It was suffi- 

 cient indeed to pour a few drops of the proto-muriate of tin 

 into the acid to precipitate the mercury in powder. Hence, 

 then, mercury inconlestably exists in the custom-house salt of 

 France. 



5. In Spain, the government put to sale the rock-salt of the 

 mines of Cordova and Minglanilla. The first time that I puri- 

 fied the salt sold at Madrid, in a silver basin, I remarked the 

 same spots as those noticed by Rouelle. 



6. Having used all the muriatic acid of Paris, I procured some 

 from the manufactory of acids at Cadahalso. That which was 

 sent to me, had been procured by means of calcined clay. It 

 contained iron, and, to my surprise, mercury also. From 

 that time I remarked, in my course of lectures, the singular 

 accordance between the salt of France and Spain in this 

 respect. 



The presence of mercury in rock salt is not astonishing, but 

 when it is found also in the salt produced by evaporation from 

 sea water, there is greater difficulty, because it must be sup- 

 posed to be in solution. There needs not, I think, more facts 

 or better proved ones, than those mentioned to establish with cer- 

 tainty the existence of mercury in the sea water of this period, 

 and that it has existed also in those which, by evaporation or 

 condensation, have given rise to the deposits of rock salt. All 

 the chemists of the last century, but one, speak of the mercury 

 of marine salt, probably from observations analogous to those 

 I have mentioned, and Rouelle remarked it before me. 



There is nothing as yet demonstrated in the origin of rock 

 salt ; nevertheless, if it should ultimately be proved that the 

 principal known mines contain mercury, it would be a new 

 demonstration that the waters of the ocean had concurred in 

 producing them ; a consequence which has been already drawn 

 from the discovery of potash in the waters of the ocean, and in 

 rock salt. 



An experiment I have desired to make for a long time, but 

 for which the opportunity has not yet offered, is to attach a 

 plate of gold, of two or three inches surface, to some part of a 

 ship, where it would be continually plunged in the water. 

 Half an ounce of gold laminated, would be amply sufficient ; 

 all that is required is, to ascertain whether, at the end of a long 



