THE DETERMINATION OF LITHIUM. 



INTRODUCTION. 



In the examination of mineral waters for litiiium there is need of 

 a method by winch small amounts of this substance may be deter- 

 mined with reasonable accuracy when only relatively small amounts 

 (from 1 to 5 liters) of water are available for this determination in 

 the general scheme of a complete mineral water analysis. Where 

 the amount of lithium present is as small as 0.001 mg per liter, the 

 evaporation of a quantity of water large enough to give a weighable 

 quantity of lithium salt consumes so much time and gives such large 

 quantities of other salts that it seems better to use a small quantity 

 of water and determine the lithium spectroscopically after it is sepa- 

 rated from the other constituents. 



In such cases the separation from the other substances in the water_ 

 is carried out according to the provisional method of the Association 

 of Official Agricultural Chemists ^ first proposed by Gooch,^ which is 

 regularly used in the water laboratory of the Bureau of Chemistry 

 wdien weighable quantities of lithium are present. The spectroscopic 

 determination is made on a solution of the sulphates of lithium, 

 sodium, and potassium obtained by the Gooch method of separation 

 with amyl alcohol. A preliminary paper by one of the authors ^ 

 read at the thirty-ninth annual meeting of the American Association 

 for the Advancement of Science, at Baltimore, 1908, gave a brief 

 outline and review of the work, making use of the spectroscope in 

 the quantitative determination of lithium and the effect of the 

 masking of the red lithium line (Lia) by various amounts of sodium 

 and potassium. In this bulletin is given a review of methods wliich 

 have been considered or tested for the separation of lithium and a 

 method developed by the authors for the determination by the 

 spectroscope of the small amount of lithium usually found in mineral 

 waters and in some other substances. 



1 U. S. Dept. Agr., Bureau of Chemistry ar. 52. 



« Amer. Chem. J., 1887, 9: 33-51. 



« Skinner. A spectroscopic method for the determination of lithium. 



