312 Ileadden — Brown Artesian Waters of Costilla Co., Colo. 



The composition- of these total solids is remarkably similar, 

 especially in their high content of silicic acid. The residue 

 from the well water contained 28*25 per cent, and that from 

 the spring water 29'25 per cent of silicic acid. This similarity 

 between the spring and well waters is not always so striking as 

 in this case, but is, as a rule, very evident. The brown water 

 area also has its springs, which are located immediately east of 

 the San Luis lake, but the pressure is not sufficient to produce 

 freely discharging springs, but instead small lakes of intensely 

 alkaline water from which is deposited, both in winter and 

 summer, considerable quantities of sodium carbonate, natron 

 associated with a little trona. 



I have given the characteristic differences between the lake 

 water and the brown artesian waters and shown that they are 

 distinct waters. The lake water is colorless, and contains nota- 

 ble quantities of silicic acid and almost as much potash as soda 

 salts. The brown waters are distinguished from the other 

 artesian waters of the basin by the presence of humus, the 

 practical absence of silicic acid, and the presence of large quan- 

 tities of sodium carbonate, from 23 to 103 grains to the imperial 

 gallon. Further, these brown waters, or such as are rich in 

 sodium carbonate, are confined to a quite sharply limited area, 

 while the colorless waters are general throughout the rest of 

 the artesian area. 



The colorless artesian waters of the basin carry only a very 

 moderate amount of dissolved substances; even the water from 

 the deepest wells contains less than 16 grains of total solids to 

 the gallon, 46 per cent which is silicic acid. These facts lead 

 us to conclude that these brown waters are the source of the 

 natron found in these soda lakes, because neither the ordinary 

 artesian waters of the valley nor the lake water nor the spring 

 waters are either rich enough in soda or pure enough to, in 

 any easily explainable way, give rise to such deposits of natron, 

 while the brown waters might easily do so. 



The facts already adduced seem sufficient to justify the 

 assumption that the natron found in these depressions owes its 

 origin to the brown waters, but there are also other facts which 

 support this view. I have submitted the water of the mill 

 well, also those of the town well at Mosca, and of the mill well 

 at Hooper, to examination with the purpose of comparing 

 them with the mother liquor, collected in the so called Soda 

 lake. Carefully made analyses of the residues from the three 

 wells show that they are identical, so that I am justified in 

 using a larger quantity of residue obtained from the mill well 

 at Hooper for the detection of iodine, bromine, lithia, titanic and 

 boric acids and in considering it as representative of the brown 

 waters in general. The substances named were found in both 

 the mother liquor from the natron and in the brown waters, 



