SOLUBILITIES OF CHEMICAL CONSTITUENTS OF ROCKS tog 
In the present paper, the essential data used are Clarke’s later 
estimates of the composition of the crust, and the same author’s esti- 
mated mean composition of river waters.t The results obtained from 
these data are supplemented by data from other sources, as shown 
below. 
ABUNDANT CONSTITUENTS OF ROCKS DISSOLVED IN 
RIVER WATERS (RECALCULATED TO 100) 
Clarke’s Mean ce GaTaaac s 
Mississippi . Cache a | Feld 
for Riversof | “Rivert | Ottawa Riverd | poudre (Colo.)§| Solution 
(CAO}s eras 48.34 51.05 Byte 20.12 14.43 
INGA Oe egos 14.61 16.45 O73 21.48 7.39 
MgO fart aR 9.55 15.86 D3 5 Ti 1.08 
K.0 Be ol 3.09 3.44 3.02 4.89 15.45 
SiO pee 19.76 T2352 BOY 34.64 57-41 
REO a. ets shee 4.65 0.68 5-59 0.65 4.24 
100.00 100.00 100.00 100.00 100.00 
* Clarke’s mean for the abundant constituents of the rivers of the earth. 
t Mississippi River water, with Na.O and K.O calculated at the ratio of 4.24 tor. Analysis by 
J. L. Porter. Annual average of Dole and Stabler as quoted by Clarke, op. cit., p. 3. 
ft Ottawa River. Analysis by F. T. Shutt, published by R. A. Daly. 
§ Cache 4 la Poudre, Colorado, Analysis by W. P. Headden. 
{ Feldspar Solution. Analysis by W. P. Headden. 
The above constituents were recalculated to too per cent in 
order that their relative amounts in the different waters might be 
readily compared. For the rock analyses this was unnecessary, 
as the abundant constituents predominate so markedly that 
their amounts would be little changed by such recalculations, 
while, for determining the relative solubilities, it is not needed. 
ABUNDANT CONSTITUENTS OF ROCKS 
igneous Sediments; | Lithospheret price Eee teen Feldspar** 
CAO co hhc 4.81 Gea 4.82 ony 0.74 0.314 
INaAO Rea en 3.41 Tf 5162) 3.28 1.60 3.10 27/28 
IMIG OS res, 0s 3.89 22 3.98 2.86 .07 0.029 
ISAO eraeaerelion AA OV 2.80 2.96 2.84 5.92 IL.592 
Oe geipeoeE 59.990 58.51 59-79 58.88 74.90 65.760 
REO Feast: « reg syil 18.69 2125) eETORss 14.48 IQ. 2091 
* Abundant Constituents in Clarke’s estimated average Igneous Rock, Op. Cit., p. 13. 
t Abundant Constituents in Clarke’s estimated average Sediment, I bid. 
{Abundant Constituents in Clarke’s estimated average Lithosphere, U.S. Geol. Surv. Bull. 330. 
Pp. 31. 
§ Estimated composition of “Surface Rocks,”’ derived by combining Igneous Rocks and Sediments 
in the ratio of one to three. 
§ Average of ee of four granites from Pike’s Peak Quadrangle by W. F. Hillebrand, Journal 
of Geology, VIII, 23 
** Analysis ‘of 4 eldspar, Horsetooth, Col. by W. P. Headden, oP. cit., p. 181. 
™F, W. Clarke, A Preliminary Study of Chemical Denudation, Smithsonian Coll., 
Vol. LVI, No. 5, p. 8, 1910. 
