WATSON — ON MURCURY IN ALLUVIAL DEPOSITS. 387 
became a subject of speculation. Accordiagly, the drain near the 
barracks of the gendarmerie was opened, but no traces were then 
discovered of the precious metal, and the subject again became a matter 
of tradition. In 1855 a company, having for its object the industrial 
development of Corsica, was formed in Paris under the comprehensive 
title of "Compagnie Miniere, Industrielle et Agricole de la Corse," its 
principle object, as set forth in the prospectus, being the search for a 
mine of mercury. The operations of this company commenced in the 
following year, and were followed out in a manner certainly novel, as 
far as regards ordinary methods of mine-exploring, but. as far as getting 
to see things geologically, on certainly the best plan that could have 
been pursued. On my arrival at Ajaccio in the summer of 1856, I 
found that M. Aqui, the gcrant of the aforesaid company, had opened a 
rude description of quarry in three floors near to the spot where the 
mercury is stated to have been found in digging the foundation of the 
houses in the Place Mourou. The quarry was placed by the side of a 
low hill, and the uppermost floor consisted merely of the rock bared by 
the removal of the soil ; the middle and lowermost floors were worked 
in the rock itself, the latter being approached by a drift driven across 
the rise of the hill from the level of the road from the barracks to the 
sea : the direction of this drift was parallel with the drain before-meu' 
tioned. I found the " shelf," thus exposed, to be a white granite, the 
felspar (both orthoclase and albite) being rather in excess of the other 
constituents. The rock was somewhat stained with oxide of iron, and 
contained patches, or rather little nests, of chlorite in the horizontal 
divisional planes, which inclined steadily towards the sea : the trans- 
verse vertical joints ran north-east and south-west. To describe all the 
points, lithological and petrological, in connection with this granite 
would take up too much space and be beside my object, but the follow- 
ing peculiarities may be enumerated: — 1st. The occurrence of little 
lenticular patches of crystallized arsenical iron-pyrites, apparently ia 
the heart of the rock, but really placed on the sides of the vertical 
divisional planes, 2nd. Kidney-shaped nodules, having a radiated struc- 
ture (called by the workmen " rognons") of the same mineral, reposing 
in little hollows in the horizontal joints, and on the surface of the rock 
immediately below the soil. 3rd. Drusy cavities, lined with a black 
meagre mineral, wliich greatly resembled carbonaceous matter, but 
which I ascertained to be mica in very minute lamina), and 4th, Thin 
