606 Dr. Walter Flight — History of Meteorites. 



appear to be olivine, partly of opaque material in which reflected 

 light reveals the presence of three substances : a sponge-like mass, 

 the thin cell-walls of which are minute crystals, some cubic in 

 form, and readily identified by their lustre with nickel -iron ; a 

 smoke-brown pulverulent lustreless substance, of which more will 

 be said below ; and diminutive yellow metallic granules, which are 

 probably magnetic pyrites. The relative position which these in- 

 gredients occupy in the mass of the rock is clearly shown in the 

 beautiful microscopic drawings accompanying Tschermak's paper. 



When a fragment of the meteorite is treated with acid the nickel- 

 iron, magnetic pyrites, and olivine decompose, and at the outset 

 a little sulphuretted hydrogen is disengaged ; soon an odour is 

 remarked like that attending the solution in acid of iron contain- 

 ing combined carbon. After prolonged action the residue is 

 still grey ; on diluting the solution with water, however, this grey 

 matter rises to the surface, or if it should happen to adhere to the 

 silica can, through its lower specific gravity, be separated by elutria- 

 tion. "When heated on platinum foil the grey substance disappears ; 

 it possesses in every respect the properties of soot. This carbon- 

 aceous matter is the dark-coloured lustreless ingredient of the matrix 

 already mentioned. 



The Goalpara stone has a specific gravity = 3444: and consists of: 



Nickel-iron 8-49 



0-85 



Hydrocarbon ... 



Olivine 



Enstatite 



Magnetic pyrites 



61-72 

 30-01 

 trace 



101-07 

 If the total amount of silica, determined by analysis, be apportioned 

 to the bases in the soluble and insoluble portion, it is found, in the 

 first instance, that the olivine contains in 100 parts : 



Silicic acid 37-81 



Iron protoxide 18-99 



Magnesia 43-20 



100-00 

 These numbers show the mineral to be made up of the silicates 

 Mg 2 Si0 4 and Fe 2 Si0 4 in the ratio of 3 : 1. The insoluble portion 

 has the following composition : 



Silicic acid 56-72 



Iron protoxide 5-33 



Magnesia 35-95 



Lime 2-00 



100-00 



The enstatite is remarkable for the small per-centage of iron oxide 

 present ; it may be a mixture of a pure magnesian enstatite with a 

 little of the ferriferous variety, bronzite, and is possibly associated 

 with a small amount of augite. 



This meteorite, it is seen, consists for the most part of olivine and 

 enstatite, an association of minerals previously noticed by Tschermak 

 in the stone which fell at Lodran (see page 601). The presence of 



