38 THE SALTON SEA. 



finally electrolyzed by depositing the copper first on a platinum dish and then on a plati- 

 num spiral weighing about 0.3 gram. A current of about 5 milliamperes was used for the 

 final deposition. 



PHOSPHATE RADICLE. 



Six liters of water were evaporated to a small volume and part of the sodium chloride 

 and calcium sulphate separated by crystallization. 



The mother-liquor was treated with concentrated nitric acid and evaporated nearly 

 to dryness in a porcelain dish to drive off hydrochloric acid. The residue was taken up 

 with water and made alkaline with ammonia. Some ammonia nitrate was added, and 

 then enough nitric acid to restore acidity, after which the phosphates were precipitated 

 in the usual way, first with molybdate solution and then with magnesia mixture. 



CARBONATE AND BICARBONATE RADICLES AND FREE CARBON DIOXIDE. 



Determinations of the carbonate and bicarbonate radicles were made in the same 

 100 c.c. sample of water. As no color developed on adding phenolphthalein, the former 

 was shown to be absent. A few drops of methyl orange were then added, and the solution 

 titrated with N/20 potassium acid sulphate solution. The number of cubic centimeters 

 required, multiplied by the factor 0.00305, gave the value of the bicarbonate radicle (HC0 3 ) 

 in grams. 



The total free and combined carbon dioxide was determined in the ordinary direct 

 way in a separate sample of water specially collected from the lake. For the decomposi- 

 tion of the carbonates dilute sulphuric acid was used, and to prevent the escape of any 

 hydrochloric acid through the action of the sulphuric acid on the salt in solution a tube 

 containing silver sulphate was interposed between the flask containing the water and the 

 Geissler potash bulb used for the absorption of the evolved carbon dioxide. By subtracting 

 from the total carbon dioxide the value corresponding to that combined as bicarbonates, 

 the free carbon dioxide was obtained. 



A third sample of 2 liters of water was evaporated to dryness on the water bath in a 

 platinum dish. The residue was transferred to a flask and the carbon dioxide, which thus 

 remained combined when the water was evaporated to dryness, was determined in the 

 same way as the total carbon dioxide. 



CHLORINE. 



Since the water was shown to contain no normal carbonates the chlorine was deter- 

 mined in the usual way by titrating 50 c.c. with standard silver nitrate solution. 



BROMINE. IODINE. ARSENATE. AND BORATE RADICLES. 



As these constituents do not occur in sufficient quantity to make accurate quantitative 

 determinations they were only tested for qualitatively. One liter of water was taken 

 for each test. 



NITRATE AND NITRITE RADICLES. 



For the determination of nitrates and nitrites the well-known colorimetric methods 

 were used. To counterbalance the effect of the sodium chloride in the water when deter- 

 mining nitrates the same quantity of salt was added to each of the standard potassium 

 mtrate preparations as was present in the 50 c.c. of water taken for this determination. 



OXYGEN CONSUMED. 



Of the water to be examined 200 c.c. were measured into a wide-mouthed glass- 

 stoppered bottle; 10 c.c. of phosphoric-acid solution (1 : 4) were then added, followed by 

 10 c.c. of a standard potassium-permanganate solution, approximately N/50. The bottle 

 and its contents were placed in a water bath and kept at a temperature of 30° C. for 4 



