2 34 Bulletin of Laboratories of Denison University. [Voi. xi 
terial is found in Socorro mountains for example as the product 
of interaction between the andesites and the overlying trachyte. 
At Socorro also are found very good clays in a peculiar zone of 
the Carboniferous. Fire clay beds are found in immediate prox- 
imity to shales with lepidodendrids like those shown in Plate 
XXXIII. Red clays from the Permian or Jura-triassic also sup- 
ply a useful variant. At Las Vegas the bluish shales of the Cre- 
taceous form an excellent base for a light red or buff brick al- 
though precaution is necessary to remove the bands of pyrites 
and fat clay to prevent discoloration. The following analyses 
of local clays will be useful. The analysis of clay No. 24 shows 
it to contain excess of clay base and it would probably be a 
useful addition to many asequia clays. Only small quantities 
would be needed as it is deficient in free silica. 
Number 
22 
23 
24 
789 
667 
515 
496 
495 
Silica, free 
48.33 
21.54 
9 47 
Silica, combined 
28. 21 
49.12 
50 22 
64.02 
29.72 
60.76 
44.48 
49 
Alumina 
5-90 
14.58 
22.26 
17-34 
11.94 
19 69 
26.32 
20.82 
Iron (Fe203) 
3-41 
.84 
2.07 
Magnesia 
trace 
1.06 
1.83 
■79 
4-43 
3-48 
Lime (CaO) 
1-54 
4-75 
3-83 
1.98 
32.11 
5.87 
13-15 
9.61 
Water combined 
2. 
2.75 
3.85 
Moisture 
4 28 
(1. 04) 
(6.4) 
Carbon dioxide 
3.16 
.67 
2.26 
Potassium 
2.43 
2.41 
2-35 
Sodium 
.80 
.68 
.84 
Clorine 
2-53 
SO3 
trace 
Iron Fe304 
5-72 
7.54 
11.03 
13-67 
Iron FeO 
26.48 
100.06 
100.18 
99.68 
Analyzed by D. W. Johnson. 
No. 22. Asequia clay from Old Albuquerque. Hon. E. S. Stover. 
No. 23. Asequia clay from Buttman’s pits. With marl nodules. 
No. 24. Red clay (Tertiary) from Bernalillo. 
No. 789. Supposed lava containing corn. Fused adobe. 
Nos. 667, 515, 496, 495. Partial analyses of basalts from White Rock 
Canon. 
No. 667. Slag from Rio Grande smelter. 
