106 



THE GEOLOGIST. 



west 38^ 15' northward, and to the east 38° 15' south; thirdly, that 

 the veins in question are generally encased in the primitive rocks 

 (granite, gneiss, mica-schist, talc-schist, &c.), never occurring higher 

 than the Silurian strata, properly so called, and belonging, therefore, to 

 a very ancient system of dislocation. Our readers will readily appre- 

 ciate all the importance and utility attached to these investigations. 



The author of the third letter, dated Copiapo, the 16th September, 

 1857, is from M. Pissis ; it relates to a geological exploration of some 

 parts of Chili. The writer informs us that he is, at present, studying 

 the province of Atacama, of which he hopes to have a geological map 

 completed before the end of 1858. The stratigraphical characters of 

 the southern parts of Chili bear a great resemblance to those of the 

 Brazils, and the upheaving of the strata seems to belong to the Hunds- 

 ruclc system ; the direction of which, in Chili, is north-east and south- 

 west, which is also that of the granite and talc-schist of the country. 

 But, independently of this, there is a large band, from fourteen to 

 eighteen leagues wide, of other formations running parallel to the coast, 

 some of the strata of which are remarkable for the abundance and 

 beautiful preservation of their fossils. The working of silver and 

 copper mines is becoming every day more and more active there, not 

 only in the inhabited districts, but even in the desert, 



A short time ago, in the year 1856, an Englishman residing in 

 South America, but whose name we cannot think of at this moment, 

 discovered the presence of silver in the water of the Atlantic Ocean. 

 He was surprised to find a small quantity of silver in the copper- 

 sheeting of vessels which had navigated for some time. He analysed, 

 first the new copper before it was placed on the ships, then the old 

 copper taken from the bottom of ships that were undergoing repair. 

 The results of his experiments were, that the copper taken from ships 

 that had navigated during the longest period of time contained the most 

 silver ; those which had only made short voyages contained very little 

 more silver than that which was originally found in the new copper- 

 sheeting.^' Similar experiments were lately made in France by MM. 

 Durocher and ^lalaguti, whose conclusions coincide with those arrived 

 at in South America. The existence of silver in sea-water cannot 

 therefore be doubted. The presence of this precious metal in the 

 waters of the ocean is without doubt due to the property possessed 

 by common salt (chloride of sodium) of dissolving chloride of silver— 

 ^' Which almost always contains slight qiiantities of silver. 



