OBSERVATIONS OF LUMINOUS METEOKS. 127 



the same fall, possibly of the ' Eisenregen ' reported on by Sarctorius 

 (died 1609) as having fallen ' im Meissnischen' at Whitsuntide, 1164. 



The Rittersgriin meteorite was found in 1833 by a workman employed 

 in clearing the forest, and offered for sale as old iron to the smith, but 

 without success ; but in 1861 it came to the notice of the lamented 

 Professor Breithaupt, and was secured for the mineral collection of the 

 Berg-Akademie, of Freiburg. Its mean diameter is - 43 metre, and its 

 weight 86'5 kilogrammes. It has recently been sawn through in Vienna, 

 a troublesome and costly labour extending over two months. An excel- 

 lent chromo-lithograph of the surface thus exposed was prepared by 

 Professor Weisbach, in 1876, and published with a few notes. 



The meshwork of nickel-iron of the siderolite encloses the following 

 minerals : troilite, asmanite, bronzite, and chromite ; the metallic portion 

 constitutes about 5P06 per cent., and the non-metallic ingredients about 

 48 - 94 per cent, of the stone. The nickel-iron contains : — 



Fe Ni Co Ca P S Si C Asmanite. 



89-990 9-740 0230 0-035 0-150 0-0] 1 0066 Trace 0056 = 100-278 



which constituents may be arranged as follows : — 



Nickel-iron Fe 9 Ni 98-995 



Iron-nickel phosphide (FeNi) 4 P .... 0-293 



Iron phosphide Fe 2 P 0-539 



Iron silicide Fe 2 Si 0-330 



Iron sulphide FeS 0-030 



Iron carbide Trace 



Copper 0-035 



Asmanite 0-056 



100-278 

 The iron sulphide, regarded as troilite, when in the form of pieces is 

 not acted upon by the magnet, and when in the form of powder but 

 feebly so. The ratios of iron to sulphur in troilite or iron monosulphite, 

 and in magnetic pyrites, differ in so small a degree that the analytical 

 results do not always put the question at rest. It is moreover a question 

 whether the meteoric sulphide, associated as it is with nickel-iron, does 

 not actually contain some of the metal as an ingredient. The numbers 

 obtained in these analyses are as follows : — 



Calculated Found 



I. II. III. 



Iron .... 63-63 65-87 63-58 63-00 



Nickel ... — 1-40 — 1-02 



Sulphur . . . 36-37 34-27 36-42 35-27 



Silicic acid . . — — — 0-67 



100-00 101-54 100-00 99-96 



The asmanite appears to have the density of 2-274-2-278, and the 

 following composition : — 



SiO 2 Fe 2 3 CaO and MgO. Loss on ignition. 

 95-77' 3-16 Trace 1-07 = 100-00 



97-84 1-65 „ 1-01 = 100-50 



As regards the crystalline form of this mineral, Weisbach considers 

 that the recent researches of Schuster and of Von Lasaulx, have placed 

 almost beyond any doubt the identity of tridymite and asmanite. It oc- 

 curred to the author that the relative solubility of tridymite and asmanite 



1 By difference. 



