Two methods were used for the separation of the iron from the nickel and cobalt—one by precipitation of the iron as basic acetate, and the other by precipitation with carbonate of baryta in the presence of an excess of chloride of ammonium; but in neither case was the separation perfected on the first precipitation, and traces of nickel remained with the iron even after the second precipitation. The nickel and cobalt were separated by means of nitrite of potash, and the cobalt was subsequently converted into sulphate and as such weighed. The lime and magnesia were separated by oxalate of ammonia, care being taken to redissolve and reprecipitate the lime to insure its being free from traces of magnesia. On spectroscopic examination of the precipitate, it proved to be lime, free from other alkaline earths.
The precipitate of iron, after being weighed, was fused with carbonate of soda; the product of the fusion was dissolved in chlorohydric acid, and the phosphoric acid precipitated with molybdate of ammonia. This phospho-molybdic precipitate was dissolved in ammonia to free it from possible traces of silica and other impurities, and the phosphoric acid precipitated from this solution by an ammoniacal mixture of sulphate of magnesia and chloride of ammonium.
The copper was precipitated as sulphide by sulphuretted hydrogen gas, redissolved in nitric acid, and determined as oxyd.
The insoluble residue, containing free silica and undecomposed silicate, was perfectly white, and free from all traces of Schreibersite. It weighed 0.1855 grm. equal to 4.24 per cent. of the specimen analyzed. It was fused with carbonate of soda, and the silica and bases determined in the usual manner. It contained 0.159 grm. silica; 0.0054 protoxyd of iron, with a minute trace of alumina; 0.0028 lime, and 0.0168 magnesia.
The soluble and insoluble portions gave in the analysis the following per centage composition:
| Considering the silica to exist as olivine. | |||
|---|---|---|---|
| Iron | 81.56 | 79.44 | |
| Nickel | 9.17 | 9.17 | |
| Cobalt | 0.44 | 0.44 | |
| Copper | 0.08 | 0.08 | |
| Phosphorus | 0.49 | 0.49 | |
| Silica | 3.63 | Combined with 2.73 Protoxyd of Iron, making Olivine | 10.07 |
| Protoxyd of Iron with trace of Alumina | 0.12 | ||
| Lime | 1.16 | ||
| Magnesia | 2.43 | ||
| Chlorine, | minute traces | traces | |
| Sulphur, | |||
| Chromium, | |||
| 99.08 | 99.69 | ||
If the silica found in this analysis be considered to exist in combination with lime, magnesia, and iron, in the proportions to form olivine, it will be necessary to deduct 2.12 per cent. from the amount of metallic iron (equal to 2.73 per cent. of protoxyd of iron), in order to give the silicate the olivine formula, (3 R O, Si O₃). Admitting this to be the correct view, the mass analyzed contains 10.07 per cent. of olivine, and by the addition of the oxygen of the protoxyd of iron the analysis adds up 99.69 instead of 99.08.
The variable composition of Schreibersite in different specimens of meteoric iron, and the peculiar character of the insoluble residue of this meteorite, together with the small amount of material in my possession, rendered it impracticable to determine the exact amount of this substance contained in the specimen.
The composition of this meteorite corresponds very closely with another meteoric-iron from Tucson, discovered by Mr. Bartlett, and described by Prof. J. Lawrence Smith, in the American Journal of Science, vol. XIX, page 161. Dr. Smith’s analysis gives Iron 85.54, Nickel 8.55, Cobalt 0.61, Copper 0.03, Phosphorus 0.12, Chromic-oxyd 0.21, Magnesia 2.04, Silica 3.02, Alumina, trace = 100.18. He considers it to correspond to Nickeliferous Iron 93.81, Chrome Iron 0.41, Schreibersite 0.84, Olivine 5.06 = 100.18. By an evident inadvertence Dr. Smith adds the magnesia and silica together, and gives the sum as olivine; these substances are obviously not in the proportions to form the silicate 3 R O, Si O₃, and if we consider the silicate to be olivine, we must reckon the excess of silica as combined with protoxyd of iron. To do this, we must deduct 2.78 from the amount of metallic iron (equal to 2.58 protoxyd of iron), necessary to be combined with the silica and magnesia to give the olivine formula. The amount of olivine contained in the Bartlett meteoric-iron will then be 8.64 per cent. Thus the two masses of iron will be seen to agree very nearly in composition, the only trifling difference being, that Dr. Smith has determined quantitatively the small amount of chromium contained in the Bartlett meteorite, while I have found a little lime and traces of sulphur and chlorine in the specimen you sent to me. The specific gravity I have stated to be 7.39; this was taken on about 12.5 grammes of the iron, and probably is somewhat higher than the portion which I analyzed, as the two surfaces of the larger mass had been rubbed down, and as thus a considerable portion of the exposed silicate would be mechanically removed, it would make the density correspondingly higher.