IOWA ACADEMY OF SCIENCE 
189 
As a rule only mineral analyses have been made, though where 
evidence pointed to large amounts of nitrate this has also been de- 
termined. The usual determinations have been, — Cl, S0 4 , HC0 3 , 
Si0 2 , Fe, Al, Ca, Mg, Na and K. Up to the present time the total 
number of analyses is about three hundred. About fifty have been 
transcribed and recalculated from Professor Norton’s Report, a 
large number have been collected from the railroads and from 
other sources, but the larger portion have been made at Grinnell. 
The railroads to which the Survey is chiefly indebted are the Chi- 
cago & North-Western, the Chicago, Milwaukee & St. Paul and the 
Rock Island. 
All the analyses obtained from railroads and other sources have 
been calculated into modern terms used by the Geological Survey. 
The old system of grains per gallon and hypothetical compounds 
has been discarded and all results save Si0 2 are expressed in ions 
and parts per million as they probably exist in solution. When 
waters are acid to phenoltalein the carbonic acid ion is assumed 
to be HC0 3 , or, all carbonates are regarded as acid carbonates. 
At the present time by no means all the general results from the 
data at hand have been worked out or even attempted. However, 
certain definite general statements can be made with reasonable 
confidence. 
It may be stated as most of us were already aware that Iowa 
ground waters are, even at the best, highly mineralized. No water 
coming from below the drift has been analyzed by the writer, which 
contained less than 250 parts of solids per million. From this 
minimum we find all grades of mineralization up to about 10,000 
parts per million. As a rule the heavily mineralized waters contain 
large amounts of the sulfates of calcium and magnesium, and some- 
times of sodium. In some cases, as in the 1,000-foot well at Mc- 
Gregor, the largest constituent of the solid matter is sodium chlo- 
ride, more than sixty per cent, of the solids of this water being 
sodium and chloride ions. As a rule, however, simple salt waters 
are not found in Iowa. The waters containing large amounts of 
salt are also charged with large quantities of calcium or sodium 
sulfate or both. So far as known to me there are, properly speak- 
ing, no magnesium sulfate waters. Almost invariably the amount 
of the calcium ion is at least twice that of the magnesium ion, and 
usually the proportion of calcium is much larger. In a few shallow 
wells sulfates are practically absent, and in a few of the best deep 
well waters, as at Vinton and Dubuque, S0 4 is all but absent, the 
