408 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 9o 



PREPARATION OF SAMPLE FOR CHEMICAL ANALYSIS 



Material for study was taken iron) the smaller specimen. The 

 fused crust was removed by using a steel dental pick, and by this same 

 instrument the central portion was found to be rather easily broken 

 apart. The material selected was carefully examined to free it from 

 the crust and then partly crushed and sized by screening through a 

 140-mesh sieve, and divided it into two portions, one of which was less 

 than 140 mesh and the other coarser, but still less than 80 mesh. This 

 step was taken in the hope that it would be possible to separate the 

 metallic portion from the silicates by using an electromagnetic 

 separator. There was enough iron dust or magnetic particles asso- 

 ciated with both fractions to prohibit satisfactory separation by the 

 electromagnet. 



A small portion of the magnetic material was removed from one of 

 the samples and unfortunately lost. This made it dangerous to 

 combine the samples again; hence each portion, the coai'se and the 

 fine, was analyzed as a separate sample. The author does not recom- 

 mend this procedure for stony meteorites, and if there had been a 

 greater quantity of material available from which to select a new 

 sample these two portions would have been discarded and a new one 

 prepared. 



The samples taken for analyses were digested in mixed nitric and 

 hydrochloric acids for 12 hours. This treatment took into solution 

 all the metallic minerals, except a grain or so of chromite, and com- 

 pletely decomposed the olivine. The silica from the olivine along 

 with the insoluble material was filtered off and the separated silica 

 subsequently removed from the insoluble residue by digestion in 

 sodium-carbonate solution. Very little of the silica separated from 

 the olivine was present in the acid filtrate; apparently the silica is 

 largely separated out if the acid stands in contact with the olivine for 

 some time. After the removal of the silica the insoluble portion was 

 carefully ignited at low temperature necessary to burn off filter paper 

 and preserved in order that it might be separately analyzed chemically 

 and mineralogically. 



Table 2 gives the results of the analysis on both the fine-grained 

 portion and the coarse. 



OLIVINE 



The composition of the olivine was determined from the analysis 

 of the soluble material. It had to be assumed that the silica, soluble 

 in the sodium carbonate, together with the small portion recovered 

 in the acid filtrates was entirely derived from the olivine. Several 

 side experiments, of a qualitative nature, were conducted, and it was 

 found that olivine is very easily attacked by acids, even weak organic 

 ones such as tartaric. The magnesium in the soluble portion was also 



