FEBRUARY 8, 1901.] 
rected upward, while between the two points 
they enter laterally. It follows from this that 
a particular body of ore may have been formed 
by ascending, descending or laterally moving 
currents, or by any or all combined. 
The level of ground water separates an outer 
belt of weathering—a belt in which oxidation, 
carbonation and hydration are producing sol- 
uble bodies—from an underlying belt of cementa- 
tion in which deposition is continually taking 
place, often in connection with solution. In 
many mining regions the processes of degrada- 
tion have removed several thousand meters of 
rock from above the present belt of weathering, 
but as the belt removed has all at some time 
been included within the belt of weathering, it 
is an adequate storehouse from which the ore 
bodies of the present belt of cementation have 
- beea supplied. Another fundamental premise 
is that materials will be more generally taken 
into solution during the descending course of 
waters and be deposited during the upward 
course toward the surface, both because the in- 
creasing pressure and temperature with increas- 
ing depth favor solution, and because the 
larger fissures near the surface —the trunk chan- 
nels—allow the mingling of solutions. Since 
the same fissure may near the surface be re- 
ceiving descending waters, a little lower down 
laterally moving currents, and at still greater 
depth ascending currents, it follows that as 
degradation brings successively lower and lower 
belts within the realm of action of ground 
waters, the first concentration of ores will, in 
general, be produced by ascending currents and 
the later concentrations (if there be any) by 
laterally moving or descending currents. The 
first concentration should be Jess in amount 
than later concentrations, a conclusion which is 
supported by observation, since nine mines out 
of ten are poorer below the 300 meter level 
than above it, and still poorer below the 600 
meter level. Inasmuch as the deep water cir- 
culation is deficient in oxygen but contains re- 
ducing agents, while the shallow water circula 
tion contains free oxygen, it is easy to explain 
the development of oxide ores in the belts near 
the surface. Dr. Van Hise holds that oxi 
dized salts, suchas sulphates, carried to greater 
depths, react upon the lean sulphides so as to 
SCLENCE. 229 
precipitate the metals as sulphides from the 
solution. The above are only the broader gen- 
eralizations in the earth’s story of the ore de- 
posits as read by Professor Van Hise. ; 
Wm. H. Hopss. 
THE TEXAS ACADEMY OF SCIENCE. 
DuRING the quarter ending December 31, 
1900, there have been three noteworthy meet- 
ings of this organization. At the first, held in 
the Chemical Lecture Room of the University 
of Texas, Friday evening, October 26th, Dr. 
Simonds, the retiring President of the Academy, 
introduced his successor, Henry Winston Har- 
per, M.D., F.C.S., who then delivered the Pres 
idential Address, his subject being ‘Some Ad 
vances in our Knowledge of Immunity and 
Protective Inoculation.’ This address will be 
published in full in SctENCE. 
The second meeting of the quarter was held 
in the Chemical Lecture Room of the Univer- 
sity, Friday evening, Noweumloge 23,1900. The 
program was as follows: 
1. ‘The Present Foundation of the Austin Dam,’ 
by Professor T. U. Taylor, University of Texas. 
2. ‘An Application of the 57.3 Rule,’ by Professor 
T. U. Taylor. 
3. ‘Eros and the Solar Parallax,’ by Dr. Harry 
Y. Benedict, University of Texas. 
The third and last meeting was held at Baye 
lor University, Waco, Texas, December 28-29, 
1900. The program was of unusual interest 
and covered a wide range. 
1. ‘The problem of Forest Management in Texas,’ 
by Dr. William L. Bray, University of Texas. 
2. ‘Recent Progress in Insect Warfare’ (by title), 
by Professor F. W. Malley, Agr. and Mech. College 
of Texas. 
‘The Value of Coal Tar Products as Practical 
Wood Preservers,’ by Instructor E. P. Schoch, Uni- 
versity of Texas. 
4. ‘A Mathematical Problem,’ by Professor J. B. 
Johnson, Baylor University. 
5. ‘The Cretaceous—the Kindergarten of Paleon- 
tology,’ by John K. Prather, B.S., Waco. 
6. ‘The Silt Problem in connection with Irriga- 
tion Storage Reservoirs,’ by Professor J. C. Nagle, 
Agr. and Mech. College of Texas. 
7. ‘The Need of Technical Education in the South,’ 
by Dr. William T. Mather, University of Texas. 
8. ‘The Modern Presentation of Botany,’ by In- 
structor A. M. Ferguson, University of Texas. 
