76 



CARNEGIE INSTITUTION OF WASHINGTON. 



relatively great, there can be no question of the actual disappearance of 

 these elements. The ratio of potassium to sodium slowly decreased 

 from about 1:48 to 1:90 or more. In the early years of the existence 

 of Salton Sea the yellow precipitate or ammonium phosphomolybdate 

 was easily secured from 1 or 2 liters of water and actually weighed, 

 but 3 liters of water in 1916 yielded no evidence of the presence of 

 phosphorus. 



It was shown by Jones^ that the tufas of the Salton Sink had been 

 deposited by algae and that the calcium carbonate disappearing from 

 the present Salton Sea could be accounted for by these tufas. Re- 

 cently one of us determined the potassium, sodium, and phosphorus in 

 the old massive tufa deposited from the former Blake Sea at Traver- 

 tine Point, and new tufa collected in 1913 from mesquite brush sub- 

 merged in the present Salton Sea. The analyses gave the following 

 result : 



The high sodium content of the recent tufa is due to the branches 

 being removed from the sea-water and dried without rinsing. Even 

 then the potassium-sodium ratio is about 1 : 6, while the sea-water 

 had a similar ratio of about 1 : 90. The fact that both potassium and 

 phosphorus have been concentrated in the tufa needs no further proof. 

 It may be questioned, however, as to what extent this concentration 

 accounts for the loss of these elements from the Salton Sea water. If 

 we assume that all the calcium lost from the water has been used in 

 forming tufa, an approximation of the amount of phosphorus and 

 potassium that would have accompanied it may be made. 



If calcium had concentrated at the same rate as total solids there 

 would have been present in 1919 about 71.34 parts. In like manner 

 the 0.009 part per 100,000 of phosphate ion present in 1917 would now 

 amount to 0.064 part. The potassium should be at present 16.49 

 parts per 100,000 instead of 9.98 parts, a loss of 6.51 parts. 



According to an analysis of the tufa deposited from Salton Sea in 

 1912 (made by C. N. Catlin^ in this laboratory), 70 per cent of calcium 

 carbonate was present. Assuming the tufa used by Griffin also to 

 contain 70 per cent calcium carbonate, we find the 27.84 parts per 

 100,000 of calcium removed from the water would require the loss of 

 0.115 part of phosphate ion and 0.19 part of potassium. 



» The Salton Sea, Carnegie Inst. Wash. Pub. No. 193, 79 (1914). 

 * Ibid., p. 47. 



