30 PROCEEDINGS OF THE CALIFORNIA 



Professor Whitney communicated the following letter from Pro- 

 fessor Brush, giving the results of a chemical investigation of the 

 meteoric iron presented to the city of San Francisco, by General 

 Carleton : 



Sheffield Laboratory of Yale College, 

 New Haven, March 30th, 1863. 



Professor J. D. Whitney, State Geologist, San Francisco, Cal. 



Dear Sir : — I have examined the specimen of meteoric iron from Tucson, 

 which you sent me for anatysis, and herewith communicate to you my results. 



The density of the mass is 7.20. When a fragment of it is placed in a solu- 

 tion of neutral sulphate of copper, it quickly becomes coated with metallic cop- 

 per, proving the iron to be " active." An inspection of the specimen with a 

 lens showed it to be dotted with little cavities, which on the fresh fracture were 

 lined with a white silicious mineral, giving the surface a porpbyritic, or pseudo- 

 porphyritic, appearance. 



When a fragment was attacked with an acid, a portion of the iron was dis- 

 solved, leaving the silicious mineral projecting from the surface of the specimen ; 

 and with a magnifier, black particles of Schreibersite could be seen. After com- 

 plete solution of the iron, a careful microscopic examination was made of the 

 insoluble residue. With a magnifying power of 25 diameters, it appeared to 

 consist chiefly of two substances : one a milk-white to transparent mineral, hav- 

 ing a fused, rounded surface, occurring in little globules, or elongated, rounded 

 particles ; while the other constituent was black and angular, and attractable 

 by the magnet. The first named substance, when observed with a magnifying 

 power of 100 diameters, proved to contain minute specks of the black mineral 

 disseminated through it ; some of the silicious fragments were translucent and 

 of a milk-white color, and others colorless and transparent ; a large number, 

 however, were transparent at one end, shading into milk-white at the other, thus 

 seeming to indicate that the transparent and translucent portions were not two 

 distinct minerals. A blowpipe examination of the silicious mineral showed it 

 to have characters very much resembling olivine. The black mineral proved to 

 be Schreibersite. A minute trace of chromium was also observed in the insolu- 

 ble residue. 



The qualitative analysis of the portion soluble in nitric acid indicated the 

 presence of iron, nickel, cobalt, copper, phosphorus, lime, and magnesia with 

 unweighable traces of chlorine, sulphur, and alumina. For the quantitative 

 examination of the meteorite a fragment weighing 4.3767 grammes was treated 

 with nitro-chlorohydric acid (aqua regia), and after solution of the iron the 

 whole was evaporated ; on approaching dryness, gelatinous silica separated, 

 showing that the silicate had been partially, at least, decomposed by the acid. 

 After heating until the silica was rendered insoluble, it was repeatedly treated 

 with acid and evaporated, so as to insure the oxydation of all the Schreibersite, 

 and finally the soluble part was taken up with chlorohydric acid, and on dilu- 

 tion separated by filtration from the silica and insoluble residue. 



