376 



PROCEEDINGS OF THE ACADEMY OF 



[1893. 



Il'OU 



Nickel . 

 Troilite (fe S) 

 Magnetite (fe. 4 ) 

 x Silicate 



Composition of the separated magnetic powder : 



Iron . . . . 68*18 per cent. 



66 - 79 per cent. 



2*32 per cent. 



0'52 per cent. 

 25-96 per cent. 



4*41 per cent. 



0"31 per cent. 



1*75 per cent. 



3 - 43 per cent. 

 1010 per cent. 

 16*23 per cent. 



Nickel . 



Sulphuric anhydrite 

 Water . 

 x Silicate 

 Oxygen 



According to well known theoretical affinities we may expect the 

 mixture to be : 



Iron .... 25*58 per cent. 



Nickel .... 031 per cent. 



Magnetite (fe 3 4 ) . . 5630 per cent. 

 Magnetic sulphate (fe 3 4 , 2 S0 3 ) 4*28 per cent. 

 x Silicate . . . lO'lO per cent. 



Water .... 3*43 per cent. 



As long as there is any troilite in the mass a further oxidation 

 and disintegration may be expected. The cellular structure of this 

 steel meteorite seems to permit of such a process continuously. 



My statement regarding the magnetic sulphate of iron, is made 

 because, first: the whole of the powder is magnetic, whilst the basic 

 sulphate of iron is not ; and, secondly : when I tried to compute it as 

 basic ferric sulphate I invariably obtained a numerical result whose 

 aggregate was 1*05% too high. When regarding it as magnetic 

 ferric sulphate no such discrepancy occurred. 



My thanks are due to Professor Angelo Heilprin for the opportu- 

 nity of investigating the first tempered steel meteorite. 



Explanation of Plate IX. 



Fig. 1. Photographic projection of the polished and etched 

 surface of the hard steel meteorite magnified about three diameters. 



Fig. 2. Cubic and octahedral forms. 



Fig. 3. Solid crystal forms as seen in the pits of the specimen. 



Fig. 4. One of the many irregular outlined forms ; the crossed 

 lines represent the cleavages. 



Figs. 2, 3 and 4 are magnified about twenty diameters. 



