Russell] COMPOSITION OF THE LAVA. 87 
and at a locality far distant not only from the ocean but from all sur- 
face-water borders, and in a region where erosion and deposition prac- 
tically counterbalance each other. 
CHEMICAL COMPOSITION. 
A characteristic sample of the lava from near the source of the 
stream that flowed northwest from the Cinder Buttes — that is, the one 
nearest the mountains on the northern side of the range of craters- 
has been analyzed with the following results: 
Analysis of recent lava from the Cinder Bnites, Idaho. 
[Analyst, W. F. Hillebrand.] 
Per cent. 
Silica, Si0 2 51.14 
Titanium dioxide, TiO, 2. 41 
Zirconium dioxide, Zi ., 0. 12 
< r. 
Alumina, A1 2 3 1 3. 
Chromic oxide, Cr 2 3 ISTone. 
Vanadium trioxide, V 2 3 Trace. 
Ferric oxide, Fe 2 3 2. 15 
Ferrous oxide, FeO 12. 97 
Manganous oxide, MnO 0.44 
Nickelous oxide, NiO Trace. 
Calcium oxide, CaO 6. 56 
Strontium oxide, SrO Faint trace. 
Barium oxide, BaO 0. 25 
Magnesium oxide, MgO 2. 21 
Potassium oxide, K 2 2. 33 
Sodium oxide, Na 2 3. 59 
Lithium oxide, Li 2 None. 
Water below 105° C, H 2 0. 12 
Water above 105° C, H 2 0. 22 
Phosphoric oxide, P 2 5 1. 59 
Carbon dioxide, C0 2 , . None. 
Chlorine, CI Trace. 
Fluorine, Fl 0. 10 
Iron disulphide, FeS 2 (S=0.08) 0. 15 
100. 30 
Less oxygen computed in place of fluorine 04 
Total 100. 26 
Specific gravity =2.907 at 24° C. 
This analysis shows the composition of a large lava flow as nearly 
as a single well-selected sample can be expected to indicate the average 
of a seemingly homogeneous terrane, and probably indicates also about 
the average composition of all the recent lava discharged from the 
Cinder Buttes. It was made with much detail, with the view not only 
of meeting present needs but of furnishing accurate data for use in 
future discussions of volcanic phenomena. 
