10 
Colorado Experiment Station 
solids to the imperial gallon, is carrying more than 50 tons of matter 
through its canyon every day. This mass of material, mostly car¬ 
bonates of lime and soda with small quantities of sodic chlorid and 
some magnesia, has been dissolved out of the rocks and means the 
breaking down of hundreds of cubic feet of solid rock every day. 
Estimated roughly the amount of material mentioned here is about 
equal to 650 cubic feet of rock which is 2^ times heavier than water. 
To make still plainer the magnitude of this action of water, we will 
take another example. We have stated that sodic carbonate consti¬ 
tutes what we call “black alkali”, and also that this carbonate is one 
of the products of the action of water on plagioclase, a felspar, which 
occurs in schists and granites as well as in igneous rocks. The water¬ 
shed from which the water drains into some of our mountain valleys 
is several thousands of square miles in area, and even though the rain¬ 
fall may be only 15 or 20 inches per annum the water that flows into 
the valley may be millions of acre-feet. In a concrete example that 
I have recently had occasion to study, the amount of water removed 
by evaporation was 1,500,000 acre-feet. This water was supplied by 
the mountain streams flowing into the valley, and, on the supposition 
that each 10 pounds of water carried 2^2 grains of sodic carbonate, 
which is about what the water actually carried, the amount of this 
salt brought into the valley every year amounted to 145,500,000 
pounds. This has been going on for many centuries and, if none of 
it has been washed out of the valley, the amount present at this time 
must be so great that we can form no adequate notion of it, and such 
are the facts, so far as we can make them out. These processes by 
which these alkalis are formed are not peculiar to our soils or our 
mountains. They are active everywhere but, in regions of heavier 
rainfall, the salts that remain in our soils and are known to us under 
the name of “alkalis” are washed out and carried, eventually, to the 
ocean, possibly not in the form in which they were dissolved out of 
the rocks, for they may change when they come in contact with other 
salts. 
I have not mentioned these sources of our alkalis as necessarily 
the immediate source of every patch of them, but in some cases it 
seems to be true as in the case of the carbonate cited in our last ex¬ 
ample. 
NITRATES FORMED IN THE SOIL AN IMPORTANT FACTOR 
There are other salts found in our alkalis which are not always 
understood as being included under our term “alkalis”. I refer to the 
nitrates and in some instances excessive quantities of calcic chlorid. 
The nitrates are being formed now just as the other alkali salts are 
being produced, by the decomposition of the minerals in the soil, but 
