Alkalis In Colorado 
51 
feet in the case of the sodic carbonate, their production has been the re¬ 
sult of the action of carbonated waters on the minerals of the surface 
rocks, and the time of the production of the alkalis with which we have 
to do in the present period. The alkalis are in no probability older 
than the artesian waters containing them but are possibly in part young¬ 
er, as they are now being formed. The mode of their formation can be 
imitated in the laboratory and is universal in its application. 
NITRATES SOMETIMES MISTAKEN FOR “BLACK ALKALI” 
I have previously made mention of the occurrence of nitrates, not 
in the sense in which these substances are usually mentioned as occur¬ 
ring in the soil, but in much larger quantities such as are sufficient to be 
very injurious. In the previous mention I suggested a doubt as to the 
propriety of including them among the alkalis. The only reason that 
would seem to justify our doing so is the fact that they have been mis¬ 
taken very frequently for “black alkali’\ Some nitrates do occur in 
the area described in this bulletin as actually suffering from the pre¬ 
sence of “black alkali”, sodic carbonate, but they are not confined to 
this condition, though their formation may be facilitated by it, provided 
it is not too bad. 
I have deemed the statement, relative to the composition of our 
river- and other surface-waters, especially as they show the absence of 
these salts, sufficient to show that their origin is not the same as that 
of our alkalis. These are formed by the action of meteoric waters on 
the rocks containing felspar, and particularly soda-lime felspars. These 
rocks do not contain nitrates nor yet any elements from which the nec- 
cessary nitric acid can be formed. I have further pointed out that the 
alkalis that we find are of recent origin, are confined to relatively shal¬ 
low depths and are to be looked upon as having penetrated the soils 
and rocks, in some cases, from the surface. We find in many places 
that under favorable conditions various kinds of rocks contain in their 
superficial parts soine nitrates but these do not penetrate very far and 
owe their formation to processes that are going on at the present time 
at the surface of these rocks. Of course these processes have been 
going on in the recent past just as they are today. 
« 
The simple facts in this case are these: We have areas varying 
greatly in size in which we find a great deal more nitrogen than in the 
surrounding lands, and a very large percentage of this nitrogen is in 
the form of nitrates. 
I have already made it plain that our soils, generally speaking, con¬ 
tain alkalis among which sodic carbonate is usually found in small, but 
not injurious quantities. In this sense the nitrates are associated with 
the alkalis but they are not necessarily associated with the efflorescences 
