CLARKE.] 
INTRODUCTION. 
17 
Si0 2 
Ti0 2 
A1A 
Fe 2 3 
FeO 
MnO 
CaO 
SrO 
BaO 
MgO 
A. 
Na 2 
Li 2 
H 2 Oat 110° 
PA- 
CO,. 
55.43 
.46 
13. 84 
4.00 
1.74 
trace 
5.96 
none 
.06 
2.67 
2.67 
1.80 
trace 
2.11 
3.45 
.20 
4.62 
m, .... 
ci 
Carbon l> 
78 
69 
100. 48 
60.15 
.76 
16. 45 
4.04 
2.90 
trace 
1.41 
none 
.04 
2.32 
3.60 
1.01 
trace 
.89 
3.82 
.15 
1.46 
58 
88 
100. 46 
C. 
58. 38 
.65 
15. 47 
4.03 
2.46 
trace 
3.12 
none 
.05 
2.45 
3.25 
1.31 
trace 
1.34 
3.68 
.17 
2.64 
65 
si 
100. 46 
78. 66 
.25 
4.78 
1*.08 
.30 
trace 
5.52 
trace 
.05 
1.17 
1.32 
.45 
trace 
.31 
a 1.33 
.08 
5.04 
.07 
trace 
100. 41 
84.86 
.41 
5.96 
1.39 
.84 
trace 
1.05 
none 
.01 
.52 
1.16 
.76 
trace 
.27 
a 1. 47 
.06 
1.01 
.09 
trace 
99.86 
5. L9 
. 06 
.81 
.54 
undet. 
.05 
42. 61 
none 
none 
7.90 
.33 
.05 
trace 
.21 
a. 56 
.04 
41.58 
.09 
.05 
.02 
100. 09 
1 Ut'.i 
.08 
1 . 75 
I 77 
fundet. 
.03 
40. 60 
none 
none 
4.49 
.58 
.62 
trace 
.30 
a. 88 
.42 
35. 58 
.07 
.07 
.01 
100. 34 
a Includes organic matter. 
b Of organic origin 
These analyses may be used for a variety of purposes. For example, 
they can help in tracing the change from an average igneous rock to 
an average sediment. They suggest something as to the characteristic 
features which distinguish a good building stone from other limestones 
and sandstones. They are applicable to the discussion of a variety of 
large theoretical problems, like that chosen by Professor Joly. These 
considerations alone justify their publication here. 
In the former edition of this bulletin (No. 14:8) a chapter upon 
analytical methods, by Dr. W. F. Hillebrand, was included. For that 
chapter there has been a large separate demand, and for that reason 
t will be expanded into a work of greater detail and issued as a 
listinct bulletin. It will be noticed that to Dr. Hillebrand many of 
:he best analyses in this compilation are due, and a full statement 
)f methods, embodying his experience, will be of the utmost value. 
During the preparation of this bulletin much assistance was rendered 
)y the petrographers and geologists connected with the Survey, espe- 
dally with reference to analyses hitherto unpublished. In each case 
redit has been given for the data thus added. Twenty-eight analyses 
Bull. 168 2 
