Scientific Intelligence, I8S 



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 lo sunshine, however powerful the sun's 

 rays, no further effects will be produced, unless a little more common 

 disvilled 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 tlie fluid is decanted and exposed to light. — Idem. 



NATURAL HISTORY. 



1 . Couzeranite. — ^M. de Charpentier, in an important work whicb 

 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 othery 

 he gave the above name, from the part of the chain in which it wa^. 

 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 edgCy 

 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 tlie 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 pyrox- 

 ene and made, 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 is 



