Alkalis In Colorado 
39 
In the northern section the effloresced salts contain some car¬ 
bonates varying from a very little up to 40 percent. We have in this 
section some deposits of pure sodic carbonate. The soil extracts con¬ 
tain 25 percent sodic carbonate, and upwards, while the ground-waters 
are even richer in carbonate than the corresponding soil extracts. We 
'would expect this, as the soil retains the sodic carbonate but feebly, 
or not at all, and consequently permits it to pass into the ground-water, 
also into the drain-waters. It is for this reason, too, that the nitrates, 
when present in the soil, are easily washed out by water that runs 
through it. 
An alkali gathered from uncultivated soil contained 8 percent of 
sodic carbonate. The aqueous extract from the soil below this con¬ 
tained more than 25 percent, and a ground-water taken in the same 
neighborhood gave a residue on being evaporated to dryness that con¬ 
tained 29 percent of soluble carbonates. These results represent a large 
area which has now become practically unproductive. Two efflores¬ 
cences gathered about 17 miles southeast of this contained 20 and 40 
percent of sodic carbonate respectively. The well-waters in this whole 
section, about 800 square miles in area, are alkaline. Shallow wells 
dug for household purposes contain, according to their depth, from 22 
grains of total solids upward, 75 or more percent of which is sodic 
carbonate. The water from a large drainage ditch which runs through 
this section from west to east is essentially the same in character as 
the water from shallow wells. The deeper the wells after they attain 
a depth of 200 feet, the richer is the water in total solids and the more 
sodic carbonate they contain. The total solids from the deep wells 
contain about 90 percent of sodic carbonate. 
These conditions are different from those described for the south¬ 
ern section, where we had calcic, magnesic, and sodic sulfates in the 
effloresced alkalis and essentially the same in the ground- and drain- 
waters, while the artesian water and that of the big springs in the 
southeastern portion of the section, contain only small amounts of total 
solids and these are poor in sulfates and chlorids but are fairly rich in 
carbonates, and are characterized by the presence of much silicic acid. 
In this northern part we have sodic sulfate as the principal salt in the 
effloresced alkalis with some carbonate. The ground-waters contained 
less sulfates and more carbonates, while shallow wells contain much 
carbonate and very little sulfates. The amount of salts and the per¬ 
centage of carbonates increase with depth. They also increase in a 
line from west to east across this section; for instance, at the west side 
of the area, where conditions are still good, the first flow of artesian 
water contains 10.6 grains of total solids to the imperial gallon with 
2.2 grains of sodic carbonate; 16 miles east of this the first flow, pre- 
