176 Fretp Museum oF NaTurRAL History — Geo toey, VoL. III. 
of the carefully sampled borings weighing 514 grams was dissolved 
in nitric acid. Although no residue was obtained, the solution was 
evaporated to dryness, ignited so as to convert the iron to sesquioxide, 
and an assay made by the crucible method. The charge used con- 
sisted of 50 grams litharge, 25 grams soda, 25 grams borax glass, 5 
grams scouring sand,and 4% grams argols. Thelead button obtained 
weighed 22 grams. On cupelling this no residue was obtained. 
A partial analysis was made of the crust of magnetic oxide de- 
scribed on page 171. Fragments of this were broken off by careful 
chiselling, and in this way .3396 grams were obtained. The material 
was evidently somewhat hydrous and more or less coated with carbon- 
ate of lime. It was dissolved by hydrochloric acid although acted on 
very slowly by that solvent. Determinations of ferrous and ferric iron 
in the solution gave: 
Calc. to Theory for 


100 Magnetite 
Fe QO). 2:.). Shayne eae ee 20.84 27.62 at 
Fes Opd ole le oan ae eee 54.60 he isa Oh 69 
75.44 hel og 100 
The remainder which was not determined quantitatively, was chiefly 
water, lime, CO,, and silica. The proportions of ferrous and ferric 
oxide shown by the analysis leave little doubt that the mineral is 
magnetite and show that the oxidation which the surface of an iron 
meteorite undergoes in its passage through the air may produce this 
mineral. 
COMPOSITION OF TAENITE. 
The composition of tznite, as is well known, varies between rather 
wide limits. As these limits do not seem as yet to have been deter- 
mined by comparison of analyses, the writer has endeavored to collect 
all existing reliable analyses in order that such determination may be 
made. The compilation of analyses together with a calculation of the 
ratio of iron to nickel-cobalt-copper will be found below: 


Fe: Ni+Co 
Fe Ni Co Cu C Total +Cu 
Tish Wl ele ok SO2,440.1 222 O.54) isc wle 5 ace ne Gl. OC car 
7 4 Coe me 85.00 14 00 ee 99.00 6.4 31 
2 Beers Aas Sete No 35 300 = 5T c. 00 ives) na, 4 {0 gaet 
— —-— a 
Ae as fe 83.28 —s2 i408 16 68 Se eee fovo4 | oo eee 2 ee 
poet POT Re ae SOn 30 sea. eae L900 MeeeeeiweroM “ae 09.90 >) aaa 
er eee a rare TALIS CIDA AS O:33° fn.. (OF5O7 aa 7 ae 
Weegee Gre ete Cc TAO, 623804 2.10 Cithw- P27) soo 3. Oran 
