362- Prof. Sti'omeyer's Analyses 



by the increased oxidation of the iron, the quantity of mag- 

 nesia was gradually lessened by the influence of atmospheric 

 moisture {meteorwasser), and that the final result of the decay 

 of the fossil would probably be a mixture of oxide of iron, 

 perhaps as hydrate, and silica ; yet I venture to attribute no 

 great weight to this examination, partly because I was able to 

 decompose only o?ie decayed olivine, and partly because the 

 opacity of the piece examined rendered it impossible for me 

 to convince myself as I wished, of its purity. 



Thei'e still remains, in every view of the case, the question, 

 In what does the cause of the olivine's great tendency to yield 

 to the influence of the atmosphere consist? for there are 

 well-known minerals with a greater proportion of protoxide 

 of iron, which are not distinguished by such a disposition to 

 decompose. I should seek it in the granular texture of the 

 mineral, and the greater penetrability which it consequently 

 has in relation to air and water ; for chrysolite, which displays 

 no granular texture, has not this tendency. Hence it would 

 merit a closer investigation, whether the olivine is not less 

 liable to such decay if its granular texture is less distinct, and 

 thereby approaches more to that of chrysolite. 



Apperidix. — To the foregoing investigation succeeds an in- 

 teresting extract from the treatise read by our distinguished 

 analyst Professor Stromeyer, in the Giittingen Society, at the 

 last celebration of their anniversary, entitled De Olivijii, Chry- 

 solithi etfossilis, quod cellulas et cavernulas ferri meteorici Pal- 

 lasii explet^ analysi chemicd. The great resemblance which 

 the mineral that occurs in the Pallas iron and fills its cavities 

 has in its exterior to olivine and chrysolite, has long occasioned 

 the conjecture that it also did not differ from these minerals in 

 its chemical constitution, and that it belongs with them to one 

 and the same mineral species. If, however, we compare the 

 analyses of it communicated by Howard and Klaproth, with 

 the results which the decompositions of the olivine and chi-yso- 

 lite by Klaproth and Vauquelin have given, this opinion will 

 still seem very doubtful. According to these experiments, in- 

 deed, the mineral from the Pallas iron consists of the same 

 component parts of which olivine and chrysolite are composed, 

 and is, like these, chiefly formed of silica, magnesia, and oxide 

 of iron. But the proportion in which these substances enter 

 into its composition differs from that in which they occur in 

 olivine and chrysolite too much for it to be njaintained that it 

 is perfectly identical with them. Yet as the experiments of 

 Howard do not correspond with those of Klaproth, and as also 

 the olivine in its composition does not correspond according 

 to those analyses in regai'd to the quantitative relation, it was 

 quite necessary that these minerals generally should be sub- 

 mitted 



