EXPERIMENTS RELATIVE TO METEORITES. 319 



of (lifforent substances wliicli portaiii, in jroncral, to five species readily disfinguisk- 

 able : tliree metallic, two stony and silicated. 



First, we find iiiclcdi/crous native iron in nialleaV)lo grains, often very small, 

 tlie com^jiosition and structure of which are idenucal with those of the iron meteor- 

 ites already described; the proportion of these i^rains is widely variable, beiui^ 

 ordinarily "comprised betweeji S and 22 per 100 of the total wei<:ht. Next, sul- 

 pliKirt of iron (troilite,) of which the de<,'ree of snlidmration seems inferior to 

 that of magnetic pyrites or pyrrhotine. It approximates to the proto-sulphuret ; 

 often occurs in isolated grains, which their color, a bronze yellow, renders easily 

 discernible; often, also, it exists in the globules of iron, where it is imperceptible 

 to the sight. It forms, in general, from 4 to 13 per 100 of the mass, and reaches 

 even 20 per 100 in the meteorite which fell 24th December, 1858, at Murcia, in 

 Sjjain. Chromatc iron, which forms the third metallic element, appears in the 

 meteorites under consideration in small black grains, analogous to those observed 

 in the serpentines. This mineral represents only from 0.2 to 2 per 100 of the 

 total mass. It was Laugier who, in 1800, pointed out the frequent occurrence 

 of chromatc iron in meteorites, [Anmdes (hi Mnscum, t. vi,) a fact whose im])ort- 

 ance approaches that of the discovery of nickel, made by Howard four years 

 earlier. Numerous analyses have subsequently confirmed the hal>itnal presence 

 of the chrome. But the prevailing constituent of meteorites of the common type 

 is a mixture of silicates, which are separated in effect by the action of acids. 

 One of these silicates, assailable even by weak acids, has most fre(pu>ntly the 

 (xtmposition of peridot ; the other, unassailable, is richer in silicic acid. Apart 

 from the slight proportion of alumina, lime, and alkali which it includes, and 

 which seems due to a mixture of other silicates, it often approximates to pyr- 

 oxene.* 



The meteorites of the comtnon type very often present a globular texture — a 

 substance, of a gray color a little deeper than the mass of the stone, I'ormed of 

 globules of diflerent sizes. These globules are principally constituted by the 

 bisilicate which we just now mentioned, and on which the acids exert no action. 

 It thence results that if we dissolve the meteorites in question in an acid, there 

 may remain at the bottom of the phial small grains not unlike gun-sh(jt. M. 

 Gustave Rose, struck with this ren)arkal)le structure, has proposed to give to the 

 meteorites of the common tyjie, in the majority of which this structure is clearly 

 manifested, the name of chondrites, derived from the CJreek word yovoixi:;, signi- 

 fying a hull or (jranukir concretion. 



Another remarkable character, frequently afforded by meteorites of this sub- 

 group, is to present surfaces of friction analogous to those mirror-lik(! slides 

 {miroirs dc glis^emcnt) which are oV»served in some ])arts of the veins of mines. 

 Their grains of metallic iron have been drawn out along those surfaces of fric- 

 tion, so as to suggest the influence of an energetic efl"ort. These rul)bed surfaces 

 are abruptly interrupted by the external glaze, which shows that they have been 

 produced previously, not only to the fall of the stones, but also to their division 

 into fragments. 



In the ui(;teorites with which we are occupied, the external bL'Ujk frit or crust 

 is always of a dull color. Most specimens of the stones of the common type 

 j)resent, after remaining some time in damp air, numerous spots of rust, owing to 

 the easy alteration of several of the substances contained in them, and especially 

 of the sulphuret of iron. This circumstance, perhaps, enables us to com})rehend 

 whv it is that these meteorites are not met with on the surface of the earth, like 



* Amoiip the numerous analyses which have (tviiicpfl this rciiiarkalile constitution, wo will 

 cite that, which M. Dainour lias made of the stone which fell l»th D-cember, IH.'kS, neai Moiit- 

 rejeau (Haute-Gaionue). {Cumptes litndus, t. xli.x, p. ;5I.) Nickelifei-ons iron, II. (JO; iiiug- 

 iietic in rites, :{.74 ; chrome iron, l.»:^:i ; peridot, 44. H:5 ; horuhlcnde alhite, IIH.UO; total, lUO. 

 M. DiilVenoy had before made the analysisof the stoue which fell rjth .Jiuie, 1841, at Chaleau- 

 Keuanl (Loiret,) which pertains to the same type. {Cvniptes lifuJus, t. xii, p. 12'M.K) 



