the Department of Le Lobe* 283 



Mr. Balbo agrees with M. de Robillant respecting this 

 species of native gold, in his learned Memoir on the auri- 

 ferous sand or' the Oreo. u Every one," says he, M knnw3 

 that gold dust is collected in the Oreo. — But I do not believe 

 it is equally known, that gold is found, not in the bed of 

 the river alone, but to the distance of several miles, every 

 where mingled more or less with the sand. — It is very posi- 

 tively asserted that it occurs in all the little rivulets between 

 Valperga and Rivara. — I endeavoured to discover whether 

 all the waters rise sufficiently near to each other to lead us 

 to suppose that they equally derive their gold from the same 

 mine ; as it is in this way that the vulgar, and even most 

 of the learned, generally account for the gold found in 

 rivers. But I was completely convinced that the waters of 

 which I speak arise from different heights at some distance 

 from one another; so that, as we cannot suppose all these 

 places to contain mines, from which the gold may be de- 

 rived, we must necessarily admit that the particles of gold 

 are not separated daily by the action of the water, and car- 

 ried along by its streams, but that the water finds them in 

 the soil itself over which it flows. — And it is further con- 

 firmed by the observation, that the auriferous strata disap- 

 pear as we proceed up the Oreo; that we find them at 

 furthest only as high as the bridge ; that above this all traces 

 of ihem are lost, though this is very far from the springs; 

 while as we descend into the plain these strata are everv day 

 exposed by the. action of the water, and particularly in 

 floods *." 



In a second part I shall speak of the theory proposed by 

 M. Napion, in his Memoir on the mountains of Canavaisf, 

 who, having observed that all the pyrites of those mountains 

 are auriferous, attributes the particles of gold to their de- 

 composition or attrition. This is the opinion of our worthy 

 colleague, Dr. Bonvoisin. 



The observations I am now about to communicate appear 

 to me still more decisive than the proofs alleged by these 



* Mem. of the Roy. Ac. of Turin for 1781*5, on the auriferous Sand of 

 Oreo, prrtii. p. 404—407. 

 fJb.forl785-C, p.S45-G. 



authors j 



