COMPOSITION AND STRUCTURE OF METEORITES 59 



The portion for the mam analysis was precipitated twice with 

 ammonia to separate iron and almnina from the other constituents. 

 The nickel was then precipitated in the ammoniacal filtrate with 

 dime thy Iglyoxime. The filtrate from the dimethylglyoxime precip- 

 itate was evaporated to dryness on the steam bath and treated 

 with strong nitric acid to expel ammonium salts and destroy the 

 excess of the dunethylglyoxime reagent. This was necessary before 

 separating cobalt, as the element can not be precipitated as sulphide 

 in the presence of dimethylglyoxime, although this compound does 

 not interfere with the determination of lime as oxalate or magnesia 

 as phosphate in the usual manner. The dry residue from the evap- 

 oration was evaporated once more with hydrochloric acid, taken 

 up in dilute hydrochloric acid, made ammoniacal, saturated with 

 hydrogen sulphide and filtered. The filtrate after freeing from H2S 

 was used for the determination of lime and magnesia. The precip- 

 itate of cobalt sulphide, somewhat contaminated with iron and some 

 other impurities was ignited, was digested in acid and precipitated 

 with ammonia, the cobalt passing into the filtrate in very small 

 volume of solution from which it was recovered and weighed as 

 C0SO4. 



The remaining acid solution was evaporated to free from nitrates 

 and precipitated with H2S. The precipitated unpure copper sul- 

 pliide was digested in a porcelain crucible, the solution made am- 

 moniacal and the impurities filtered out. The filtrate was again 

 acidified with hydrochloric acid and again precipitated with H2S, 

 ignited in a small tared porcelain crucible, digested in the crucible 

 with a few drops of nitric acid, evaporated to dryness, and weighed 

 as CuO. No platinum could be detected in the amount of material 

 used. The results of analysis of this portion were as follows: 



Soluble silicate: Grams 



Si02 0. 0404 



AI2O3 Trace. 



TiOz Trace. 



FeO .0187 



CaO Trace. 



MgO .0435 



Total 0. 1026 



Troilite: 



Fe .0151 



S .0087 



Total . 0238 



59587—30 5 



