EXPERIMENTS RELATIVE TO METEORITES. 317 



Tlie structure of lt'n'uj;-inous meteorites is among tlie most remarkuhle. In 

 order to observe it, after haviiig ])olislied a surface <»f the bolide, we submit it to 

 the action of an acid ; we thus bring to view tlie figures called WidmumUlUen, 

 from the name of the savant who first mentioned them. In this way we ascer- 

 tiiin that the body in question is at once crystalline and heterogeneous. An 

 miassailable matter, in efi'ect, soon apjjears in relief and transibnus the surfticc, 

 originally ])laiie, into an actual stereittype plate, suitable for producing impres- 

 sions. The substance which thus appears in relief is simi»ly the multiple phos- 

 phuret of 13erzelius. This phosphuiet ])resents itself ordiuarily in ihiii laminio, 

 the intervals of which remind us, by their iineness and their parallelism, of a 

 series of strokes of the l)uiin. The different lamiiue, which thus traverse the 

 meteoric iron, are generally directed parallel to the faces of the regular octahe- 

 dron. This fact, easily to be verified in the iron meteorite discovered at Caille, 

 is the more interesting as the terrestrial iron, which is ])roduced in crystalline 

 masses, presents a cubic arrangement. If we follow the direction foricniafioiij 

 of the octahedrons, it will be recognized that, in many masses of iron, they pre- 

 sent a parallelism, whence it results that they constitute in their enscmhle a 

 single crystal. The dimension, thus considerable, of these crystals contrasts with 

 the structure observed in artificial iron, even when its crystalline state is as com- 

 plete as possible; for even then the laminae of cleavage occur in all directions, 

 as is seen in a mnltij)licity of minerals and terrestrial rocks, such as lamellar lime- 

 stone. Other procedures also have been employed for studying the structure of 

 meteorites. {Cvmufcs licndiis de V Acadcmie des Sciences, t. Ixiv, p. 6&o, 1307; 

 t. Ixv, 11. 148, 1867.) 



The falls of iron meteorites are incomparably more rare, at least at the present 

 epoch, than the falls of those of stone. There have been oljsen'ed in Europe 

 ])nt two which were quite certain in more than a century : one in 1751, at liranau, 

 in Bohemia; the other at Agram, in Croatia, in 181/. Nevertheless, there have 

 been collected in different regit)ns of the globe, particularly in Europe, in Siberia. 

 the United States, Mexico, Brazil, and in Africa, metallic masses, to which theii 

 composition justifies ns in assigning an extra-terrestrial origin with as much cer- 

 tainty as if they had been seen to fall. 1 hree of tiiese complete masses, which 

 are in the gallery of the museum, afford an idea of the interesting peculiarities 

 presented b}' the asj)ect and stiucture oi' meteoric iron. They dis))lay the frag- 

 mentary forms affected l)y these masses— Jbrins which equally characteri-ze, as wiii 

 be seen further on, the stony ma-sses, properly so calletl. 



II. — METEORJTKS OJF THE SECOND GHOXTP, OR STSSIDEROUS. 



Certain iron motconctvi, \ii place of being massive, include stony portions dis- 

 seminated in rt htcinllic pdcffe w'nicli possesses continuiiy and forms* a sort of 

 wctdllic spohfjc. "i'hey tlius const ituce a first term of the transition of meteorites 

 of iron to those of stone. 



In t',ie ..le.st known representative of the meteorites of this second group, the 

 stony iiiatier, M'nose grains are imbedded in the iron, consists of a silicate with 

 a ba.je of maguesiuni and of ju'otoxide of iron, constituting j)recisely the terres- 

 trial .•^itecies known l»y the name o[ peridot. This arrangement recalls in a strik- 

 ing manner certain products of iron accidentally formed in the workshops, in 

 vvhich the silicated scoria performs the part fulfilled by the peridot in the mete- 

 orites with which we are occupied. The meteorites of this second grouj) aro 

 particularly represented by a celebrated mass of iron, discovered byJ'allas, at 

 Krasnojarsk, in Siberia, and by another altogether similar, which was found ia 

 the desert of Atacama, in Chili. 



The stony matter of these meteorites, to nhicli we give the name of sj/ssider- 

 * does not always consist exclusively of peridot. It sometimes comprises, 



• From the Greek cvi', {wilh,) to cxpiuss tlu; continuity of the iiuii, uud cfiS^/wf, {iron.) 



OltS 



