oZZ EXrERIMENTS RELATIVE TO METEORITES. 



has studied the carhonaccous meteorite of Orgueil, and chiefly the state of com- 

 bination of the carbon, [Comptes RcnduSj t. Iviii, 1864). il. Pisani, on his part, 

 has examined this hist meteorite, principally with reference to the stony matter. 



APPENDIX TO THE PRECEDING GROUPS. PULVERULENT METEORITES. 



The slcies furnish not only coherent masses, stony or metallic, but also pul- 

 verulent matter. 'J'he existence of this meteoric dust has not attracted, so much 

 as it should have done, the attention of savants. This circumstance may be 

 referred to the extreme difficulty of distinguishing the dust -which is tndycosmi- 

 cal, from that whoso origin is terrestrial, and which is, beyond comparison, most 

 abundant. 



To the examples cited above, of the descent of terrestrial matter, we may add, 

 as well-known, the pretended showers of sulphur resulting from the fall of pol- 

 lenic dust, and certain silicious rains, which Ehrenberg has recognized as Ijcing 

 formed by the carapace or shells of infusoria. But, apart from tliese terrestrial 

 substances, we should distinguish those which are really cosmical. For example, 

 in some meteoric falls, the stones have been accompanied by dust. Thus, 14th 

 JIarch, 1813, at the same time that there fell at Cutro, in the Calabrias, a quan- 

 tity of stones, an abundance of red powder was collected.* Again, 5th Novem- 

 ber, 1814, it was remarked that the 19 stones picked up at Doab, in India, were 

 enveloped, as it were, in a pulverulent matter. 



In certain cases, the fall of dust has been ol)served without the accompani- 

 ment of stones, but always announced ])y those remarkable phenomena of light 

 and sound which we have already descril)ed. The catalogue which Chladni 

 published in 1842 makes known a number of examples, and among them the 

 following. h\ 1819, at Jlontreal, (Canada,) a black rain was observed, accom- 

 panied by an extraordinary obscuration of the sky, by detonations comparable 

 to those of discharges of artillery, and by I he most brilliant glean)s of light. 

 At first the burning of some forest in the vicinity, in coincidence with a violent 

 storm, was supposed, but the collective phenomena, and an examination of the 

 matter which fell, analogous perhaps to the meteorite of Orgueil, proved that the 

 disturbance was due to the arrival in the atmosphere of substances foreign to 

 our globe. At Loeban, in Saxony, there fell, 13th January', 1835, a powder 

 formed of oxide of magnetic iron. This followed the explosion of a bolide, 

 which moved, it is said, with extraordinary velocity, while the detached frag- 

 ments appeared to blaze in traversing the atmosphere. 



It is perhaps to meteoric dust that we should ascribe the trails which follow 

 the meteorites at the moment of their explosion ; perhaps, also, it is to the com- 

 bustion of this dust that the incandescence of bolides is in part due. The car- 

 bonaceous meteorite of Orgueil, so interesting in many points of view, has been 

 highly instructive as regards the existence of meteoric dust. It is so friable that 

 some pieces are reduced to powder by simple pressure between the fingers ; it 

 is matter of surprise that they should liavo reached the surface of the earth 

 entire. This fact may perhaps be explained bv remarking the two following 

 circumstances: First, each fragment was enveloped, at the moment of its fall, 

 in a vitrified crust, more solid than the rest of the mass. Besides, the ditlerent 

 parts of the meteorite are cemented by alkaline salts ; water, by dissolviiig this 

 cement, occasions the complete disintegration of the meteorite, which is reduced 

 '^ ft dust of the utmost tenuity. t Had the sky, on the 14th IMay, 1SG4, instead 



* Bibliothcque Britnnnique, 1813 and J8)4. Admiial KruseDsteni was witness of a i'iict 

 which should lio cited on this occcsion. Ho observed, in liis voyaj:;e around tho world, a 

 bolide which left behind it a Inniinous trail, renTiirkable for it3 pertsistence ; it continued to 

 sliine for an entire hour, without sensibly changing its place. 



t The powder in question traverses even the closest filters. 



