Scientific Intelligence. 183 
the discoloration is strong. 'To prove that the cause of change as- 
signed is the true one, it is only necessary to decant the colorless so- 
lution and expose it again to sunshine, however powerful the sun’s 
rays, no further effects will be produced, unless a little more common 
distilled water be added, and then it reappears. When used as a test 
for such substances, of course any chloride of silver that may be 
formed in consequence of the presence of muriates should be allowed 
to subside in the dark, and the subsidence should be complete be- 
fore the fluid is decanted and exposed to light.—Idem. 
NATURAL HISTORY. 
1. Couzeranite—M. de Charpentier, in an important work which 
he has published on the geological constitution of the Pyrenees, an- 
nounces that he has frequently found in the transition limestone of 
that country, a mineral to which, as he could not refer it to any other, 
he gave the above name, from the part of the chain in which it was 
principally found, and which is called Couzeran. This mineral has 
been examined by Dufrenoy. The primitive, which is also the pre- 
‘vailing form, is an oblique rhomboidal prism, resting on one edge, 
except that in the latter, there is frequently a truncation on the ob- 
tuse edges. ‘The crystals are rarely terminated, and they are striated 
longitudinally, fracture, slightly lamellar, parallel to the shorter dia- 
gonal, and conchoidal and unequal in the other direction ; splendor, 
Vitreous and resinite, which gives the fragments some resemblance to 
hilvaite. Crystals, opake ; hardness, scratches glass but not quartz; 
color, commonly perfect black, probably from carbon, like that of 
the limestone which envelopes it; sp. gr. 2.69; fusible by the blow- 
pipe into a white enamel, somewhat like felspar; acids do not affect 
it. From these external characters, it has some analogy to pytox- 
ene and macle, but its fracture is very different; and its fusibility into 
a white enamel, prevents its being confounded with either. 
Its composition agreeably to the analyses of Dufrenoy oie : 
Silica, - ; anand 
Alumine, - - - Eins 
i e, = ~ _ ~ = . 
‘ ia 0.0140 
Magnesia, - “ Z : 
ealae: ol set lies 20S eerie eo 
Soda, aie ee , = = 
0.9912 
- Annales des Mines, tome IV. 327. 
