24 HOT SPRINGS, ARKANSAS. 



The amyl alcohol was then filtered off in a weighed platinum dish and 

 the filter washed with a little amy] alcohol that was also allowed to run 

 into the dish. The amyl aleohol was driven off from the filter and beaker 

 in the air bath and these two kept for the determinations of potassium 

 and sodium. The contents of the platinum dish were evaporated to 

 dryness, treated with a little dilute sulphuric acid, and finally burned 

 and weighed. This gave the weight of the lithium sulphate 1 , from 

 which was subtracted 0.0017 gram to correct for the solubility of the 

 sodium and potassium chlorides in the amyl alcohol. The residue was 

 finally tested with the spectroscope for the lithium line. In every case 

 the lithium line was found, but in no case was an} T lithium sulphate 

 left after applying the correction of 0.0017 gram. The lithium was 

 therefore reported as traces. 



The contents of the beaker and filter from which the amyl alcohol 

 had been driven were then used for the determination of potassium 

 and sodium. The contents of the beaker were dissolved in hot water 

 and passed through the filter, which was thoroughly washed. The 

 combined filtrate and washings were transferred to a porcelain dish, 

 treated with platinum chloride solution, and evaporated nearly to dry- 

 ness. The residue was treated with 80 per cent alcohol and thoroughly 

 washed on the filter with this medium until all platinum chloride had 

 been washed out. The filter paper was dried at the temperature of 

 boiling water, and the residue dissolved in water and passed into a 

 weighed platinum dish from which the water was evaporated off. the 

 disband contents dried at the temperature of boiling water, and finally 

 weighed as potassium platinic chloride. An addition of 0.0008 gram 

 of potassium chloride to the weight of this substance found is necessary. 



The weight of the sodium chloride is found by subtracting the com- 

 bined weights of the lithium chloride (in this case nothing) and the 

 potassium chloride (corrected) from the total weight of the three 

 chlorides. 



Of course, if the amyl alcohol in the determination of lithium above 

 is not evaporated to exactly 15 cc, the corrections will be different from 

 those mentioned above. a 



Phosphoric acid. — A third aliquot portion from the filtrate men- 

 tioned above was treated with about 10 cc. (con.) nitric acid and evap- 

 orated in a porcelain dish nearly to dryness to drive off hydrochloric 

 acid. The residue was taken up with water and if necessary filtered. 

 Ammonia was added to alkalinity and then nitric acid to just bring 

 back to acidity. Some ammonium nitrate was added and the beaker 

 heated in the water bath to 15- to 50° C. Molvbdate solution was 

 then added and the solution kept at a temperature of 15° to 50° C. for 

 half an hour. The yellow precipitate formed at this point appeared 

 in most cases only in traces, but in a few cases it was filtered off and 

 washed with cold water till it was entirely free of nitric and molybdic 

 acids. The precipitate and filter were then transferred to a beaker, 

 a little water added, and the paper and contents thoroughly beaten 

 into a pulp. The yellow precipitate was then dissolved by the addi- 

 tion of a small amount of standard potassium hydroxide solution 

 (1 c. c. — 1 milligram of P 2 5 ); phenolphthalein was added and the 

 solution titrated with standard nitric acid solution of exacth' the same 

 strength as the alkaline solution. From the data so obtained the 



a For the discussion of this, see the original article already mentioned. 



