IOWA ACADEMY OP SCIENCE 
149 ,. 
“The two great acids of nature are carbonic and silicic and the major 
contest in the rocks, so far as the acids are concerned, is between the 
weak carbonic and the very weak silicic. The fact 
- of the formation of carbonates and the simultaneous decomposition of 
the silicates under surface conditions the world over is well known.” 
The limits of our space do not permit a more extended presentation 
of our studies. You will be gratified — following the interest which you 
so generously displayed two years ago and today — you will be gratified 
to knoAV that the mining engineering and chemistry departments of 
several of our colleges and state institutions are pursuing most thor- 
ough and careful studies of the action of groundwaters, acid and alka- 
line, and sewage waters upon the body of cement concrete and we urge 
again your continued interest and co-operation. 
