414 Thirtieth Annual Report 



showed a similar ratio of about 1 : 90. There was an unmistakable 

 concentration of potassium in the recent tufa. 



With regard to phosphorus estimated as phosphate ion the 

 ancient tufa contained .167 percent and the modern tufa .116 per- 

 cent. The formation of the tufa was undoubtedly accompanied by 

 the fixation of phosphorus. In the first few years after the filling of 

 the sink a distinct and even weighable precipitate of ammonium 

 phosphomolybdate could be formed from one or two liters of the 

 water, but in 1916 no positive reaction for phosphorus could be 

 gotten by working three liters of the water. 



If calcium had concentrated at the same rate as total solids 

 there would have been about 71.34 parts per 100,000 of calcium in 

 1919 instead of 43.5 parts. Thus, the equivalent of 27.84 parts per 

 100,000 of calcium has been lost. In like manner the .009 parts of 

 phosphate ion present in 1907 would now amount to .064 parts, 

 whereas all has been lost. There should also be at present 16.49 

 parts per 100,000 of potassium instead of 9.98 parts ; that is, there 

 has been a loss of 6.51 parts of potassium. 



An analysis of the tufa being deposited from Salton Sea in 1912 

 made in this laboratory by Mr. C. N. Catlin and published in "The 

 Salton Sea" (Carnegie Institution of Washington, page 47) gave 

 about 70 percent of calcium carbonate. Assuming that the tufa 

 used by 'Griflin also contained 70 percent of calcium carbonate, we 

 find the 27.84 parts of calcium lost from the water, would require 

 the loss of .115 parts of phosphate ion and .19 parts of potassium. 

 Thus the loss of the entire amount of phosphorus originally present 

 can be attributed to the formation of the tufa, but only about 3 

 percent of the potassium lost can be accounted for in this way. It 

 appears, therefore, that nearly all the potassium that has disap- 

 peared from the Salton water must have been adsorbed. (See 

 Abstraction of Potassium during Sedimentation, J. W. Watson. 

 Thesis, University of Virginia, 1913.) Deep deposits of mud have 

 been thrown up on the flat shore lines along the eastern margin 

 of the sea near Nilands. These muds may contain a large part of 

 the lost potassium. 



