282 gold mi\i:s !?: ihancb. 



of tlir rtihg* of Gardette annually avail themselves of this 

 desertion, a: during the ffaad time of the year they search for 

 gold at their own expense, ami are frequently successful. 

 £ 1 Rbo'w° f TheRhone nae; been frequently quoted for its golden 



sands. The most ancient authors, as Pliny, Diodorus Sicu- 

 lus, Strata*., and Polvbius, speak of the gold dust, which 

 this river rolls ale. ng with its sands; and which the Gauls 

 knew how to wash so as to extract the gold, of which they 

 made rings, bracelets, and belts. Reaumur, aft-r having 

 given the history of rivers and rivulets with aunfereu sands 

 in the Memoirs of the Academy of Sciences for 1778, •• ys, 

 that the gold collected In the Rhone is 20 ca>*ats tine, con- 

 taining one sixth of its weight of copper and silver. 



I shall now proceed to the mines of gold alloyed with dif- 

 ferent metals, by which its presence is concealed. 



1. Gold in the sulphuret of lead of Pontraut, 



Gold instil- Pontraut is a part of the chain of granitic mountains 

 ** c known by the name bf : Petites Rousiesi above Gz and Vau- 



jani in Oifans. This vein is near the glaciers; it is more 

 than two hours journey from the villages -abovementioned, 

 and in a country so cold, that it is inhabitable only four 

 months of the year at most. The ore of Pontraut yields to 

 the essay 58 per ceut of lead: and this lead contains 

 12*2-286 gr. of silver, and 1*442 of gold, in 5Q000. 



2. Cold in the Sulphuret of lead ofMottard. 



another: Mollard is a village of the commune of Allemont, situate 



on the right bank of the river Olle. The mine was opened 

 by Mr. Schreiber in 1785 for the smelting works of Alle- 

 mont. 



This ore yields 60 per cent of lead : and 50000 gr, of the 

 lead contain 6i"143 of silver, and 1*272 of gold. 



3. Gold in the sulphuret of antimony of Auris in Oisans. 



in tutyhumt of The. ore is a mixture of lead, zinc, copper, antimony, sil- 

 antimony : ^ eYj an d gold, united and intimately mixed. It is frequently 

 coloured by green carbonate of copper. 



It yields 50 per cent of antimony: and J 0000 gr. of this 



antimony 



