4^0 
Scientific Intelligence. 
which does not shoot into the superincumbent sandstone. Se- 
ven strata of sandstone have been cut through by the mining 
operations^ of which some are metalliferous, others not. 
1st stratum, metalliferous, - 6 metres. 
Sd stratum, sterile, - 5 
3d stratum, metalliferous, - 6 
4th stratum, sterile, - 2 
5th stratum, metalliferous, - 3 
6th stratum, sterile, - - 1 
7th stratum, metalliferous, - 1 
24 metres. 
The blue copper occurs sometimes irregularly disseminated in 
the sandstone ; sometimes in masses from the size of a pea to 
that of a man’s head, and these are either pure or intermixed 
with grains of felspar and quartz, or the crystals are enveloped 
in a fine clay. The malachite and red iron-ore have the same 
geognostical position as the blue copper. Cordier, to whom we 
owe the preceding description, considers the sandstone as a me- 
chanical deposit, and hence has great difficulty in explaining the 
mode of occurrence of the ores. We are convinced that the 
sandstone and ore have been in solution at the same time, and 
therefore are to be considered as the result of a cotemporaneous 
process of crystallisation. 
25. Primitive Form of Chromate of Lead.-^yi. Soret of Ge- 
neva has described sixteen crystallisations of this valuable mine- 
ral: he makes its primitive form an oblique prism, of which the 
transverse section is a rhomb of about 91® 27' and 88® 32', 
and in which the incidence of P upon the arret H is 102® 51'. 
The ratib of oile of the sides of the base to one of the arrets of 
the prism is as 7 to 18. This primitive form, as well as that 
given by tlaiiy, is compatible with the optical properties of this 
crystal, as determined by Dr Brewster. See the Annales des 
Mines ^ 1818, tom. hi. p. 479. 
26. Primitive Form Cinnabar. — From the examination 
of two crystals of cinnabar, the Abbe Haiiy was led to consider 
its primitive form as a regular hexahedral prism. In conse- 
quence, however, of having received a complete set of crystals 
from the mine of Almaden in Spain, he has now found that its 
primitive form is an acute rhomboid. The smallest incidences 
