1848.] Meteoric Iron from the Kurruckpore hills. 549 



Cape of Good Hope might have given different results from a splinter 

 off Cape Comorin ; and a knob from one of the Andes, with a vein of 

 silver in it, might differ widely from a fragment of Madagascar or Sibe- 

 ria or Sussex. When our specimen was an incandescent spheroid (as- 

 suming it to have once been so), the scoriaceous and purely metallic 

 parts may have made spots and districts on the nucleus as marked as 

 the various formations of our globe. 



In the examination of both I find a minute portion of the insoluble 

 residuum described by Boussingault, (Journal of Science, Vol. 17. p. 

 395,) which is in the form of a black dense granular powder,* and in 

 ours is wholly insoluble in nitro-muriatic acid, and even fusion in caustic 

 potass alone has very little effect upon it. The only menstruum which 

 will properly act upon it, being a mixture of caustic and nitrate of 

 potass, which by long fusion dissolves out the chromium as a chromate 

 of potass, when the powder is first carefully pulverised, and the heat 

 kept very high. By the blowpipe the chromium is readily detected by 

 microcosmic salt on the platina wire, the iron separating as a metallic 

 bead, and the assay bead remaining dull from the silica in the compound. 

 It appears to be a silico-chromate of iron, but with such minute assays 

 it is impossible to say more at present of such a refractory compound 

 than that it contains silica, iron and chromium, the silica and iron being 

 in large proportions and the chromium in a very small one. It may 

 possibly be a siliceous sub-chromate of iron ? 



With reference to the presence of the arsenic (which was distinctly 

 ascertained by Marsh's process), and to what I have said above as to 

 the successive oversights of first-rate chemists, the following extract 

 from a notice of M. Walchner entitled " Observations on the general 

 distribution of copper and arsenic" in the Comptes Rendus Septembre, 

 1846, which I take from the Quarterly Journal of the Geological Society 

 may not be out of place. 



After affirming the presence of copper and arsenic in many iron ores, 

 mineral springs, soils, rocks, &c. the author goes on to say, — 



"It now remained to demonstrate that these metals were equally 



* I think also so described by some other chemist, but I cannot now find the 

 reference. 



4 c 2 



