THE HI ST OR Y OF TIN. 83 



The second theory described above does not attribute the heat acquired en- 

 tirely to chemical action. In fact, this, in many cases, is of such a nature as to 

 absorb heat rather than generate it. Such would be the decomposition of chlo- 

 rides, sulphates and carbonates by silica. It looks to the great heat in the interior 

 of the earth as one of the important causes. 



It has long been known that there is an intimate relation between earthquakes 

 and volcanoes Earthquakes are a series of terrestrial vibrations which extend 

 from a center as sound waves widen from the place where the air is first set in 

 motion. Now, when the great quantities of gases, which are held under pressure, 

 break through the opening in the rocks, or force new openings if none already 

 exist, great vibrations must follow. This might frequently happen without the 

 escape of gas at the surface, the passage being from one interior cavity to an- 

 other. 



It is counted a sign of an earthquake for an active volcano to cease its flow 

 of lava. This, I think, simply means that whenever the lava stops flowing, some- 

 thing has obstructed the passage of gas from its great reservoir to its outlet, and, 

 before long, pressure becomes so great that it breaks through in the same or in 

 another place. 



THE HISTORY OF TIN. 



From an interesting paper by E. Reyer, in the Austrian Zeitschrift fiir 

 Berg-und Hilttenwesen (Vol. xxviii. , 1880) we gather the following particulars 

 concerning the history of tin. The most ancient names for this metal (Indian, 

 naga ; Persian, aonya ; Hebrew, anak ; Ethiopian, naak) indicate that its earliest 

 source' was Farther India, from the greater placer deposits of which it was 

 distributed over Asia and eastern Africa. The Mediterranean name, kasstieros, 

 used by Homer, was probably spread by the Phoenicians through their commer- 

 cial world ; and its prevalence from 1000 b. c. indicates the supply of tin through 

 these enterprising traders from Spain and also from Britain. Perhaps they 

 carried the name, though not the article, even to India. At least, it is certain 

 that, in the centuries just preceding the Christian era, tbe name kastira occurs for 

 tin in Indian documents, instead of the more ancient native term. 



The bronze manufacture of China, which flourished as early as 1800 b. c. , 

 and the equally ancient industry of India, must have required large quantities of 

 tin from the Indian placers. 



During the commercial supremacy of the Phoenicians, Cadiz in Spain was 

 the principal metropolis. After the Roman conquest of Spain, the British tin 

 trade took a new route. Caesar speaks of the plumbum album of Britain ; and 

 DiODORUs relates that it was found as ore in the rocks, and that the smelted 

 metal was carried in bars to Iktis (the Isle of Wight), thence' to Gaul, and 

 through Gaul on horses to the Rhone. Marseilles was the shipping port, 

 and soon assumed for this trade the position formerly held by Cadiz. 



