Gahbroid Rocks of Minnesota. — Wi?ichell. 377 
Table V. The relative number of molecules of each oxide, (Z), on 
the scale of one hundred. 
6 
o3 
C8 . 
a 
c 
C5 
Hi 
335 
0" 

§2 
'I 6 
.11. 
SiOg 
51.14 
53.79 
53.71 
57.55 
41.01 
56.47 
60.33 
63.80 
30.31 
TiOs 
1.44 
.48 
.90 
1.97 
1.26 
1.34 
Al.O, 
12.01 
13.15 
12.21 
19.97 
9.65 
10.38 
15.86 
11.83 
6.65 
Fe303 
.35 
2.07 
.37 
.15 
3.17 
2.55 
.28 
1.07 
16.15 
PeO 
7.89 
9.15 
7.09 
.58 
14.57 
11.06 
9.51 
3.84 
39.40 
MnO. 
.47 
.07 
.38 
.59 
.42 
.38 
MgO 
13.90 
7.68 
10.51 
1.74 
18.03 
4.75 
5.41 
5.35 
4.12 
CaO 
10.28 
10.30 
10.07 
14.69 
8.87 
8.38 
4.79 
7.59 
2.33 
Na^O 
2.03 
2.98 
3.50 
4.91 
2.28 
3.53 
2.92 
4.86 
.57 
K„0 
.36 
.40 
.57 
.34 
.27 
1.03 
.48 
.32 
.09 
100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100. CO 
Table VI. The relative number of atoms of each o.\ide iAZ) on the 
scale of one hundred. 
0) c 
.si 
6 
Sg 
0«2 
•- 
■5, . 

u 
* . 
t. SOI 

SiOs 
53.91 
53.68 
55.27 
53.43 
45.41 
57.53 
57.99 
63.24 
30..37 
AI2O3 
2(J.51 
21.68 
20.60 
30.89 
16.99 
17.21 
25.41 
19.15 
11.11 
Fe..O., 
5.99 
9.45 
5.72 
.63 
15.96 
11.98 
6.80 
4.22 
53.55 
MgO 
9.50 
5.06 
7.09 
1.08 
12.70 
3.16 
3.47 
3.46 
2.75 
CaO 
7.03 
6.79 
7.20 
9.09 
6.25 
5.57 
3.07 
4.91 
1.56 
Na^O 
2.69 
2.95 
3.55 
4.56 
2.41 
3.52 
2.80 
4.71 
.57 
KgO 
.37 
.39 
.ot 
.32 
.28 
1.03 
.46 
..31 
.09 
100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 
Table VII. The relative number of atoms of each metal (MAZ), on 
the scale of one hundred. 
22 
■=J2 
33 
.2-* 
OQ2 
11 
2 

E-r 

« . 
P. 
■2-ot-. 
i. SOS 

N .0 
.if. 
Si(Ti) 
45.59 
45.76 
46.81 
45.91 
37.26 
49.14 
50.47 
55.17 
24.55 
Al 
20.82 
22.18 
20.94 
.31.85 
16.73 
17.67 
26.53 
20.04 
10.78 
Fe(Mn) 
7.45 
11.21 
7.il 
.76 
18.26 
14.26 
8.77 
5.07 
58.37 
Mg 
12.05 
6.47 
9.01 
1.39 
15.63 
4.1)5 
4 .53 
4.53 
3.33 
Ca 
8.91 
8.68 
9.15 
11.72 
7.QP 
7.13 
4.01 
6.43 
1.89 
Na 
4.55 
5.03 
6.01 
7.83 
3.96 
6.00 
4.88 
8.22 
.93 
K 
.63 
.67 
.97 
.54 
.47 
1.75 
.81 
.54 
.15 
100.00 100.00 100.00 100.00 100.00 100.10 100.00 10(1.00 100.00 
Application of the differcjit methods of graphic rcpre- 
sentatio7i of the chemical composition of igneous rocks. .Sev- 
eral petrographers have recently attempted to represent 
graphically the chemical composition of various rocks. The 
diagrams obtained by the diverse methods proposed have cer- 
tain advantages and certain disadvantages. It will not be 
