Kreider and Breckenridge — Potassium and Sodium, etc. 263 



Art. XXXYI. — The Separation and Identification of Potas- 

 sium and Sodium^ by D. Albert Kreider and J. E. 

 Breckenridge. 



f Contributions from the Kent Chemical Laboratory of Tale University — LVI.] 



The application of the spectroscope to the detection of 

 potassium and sodium, for which there has thus far been no 

 alternative, is not so unsatisfactory in the evidence as to the 

 presence or absence of these elements as it is in its utter fail- 

 ure, except under delicate quantitative comparisons, to give 

 any idea as to the quantity of either element indicated ; and 

 since the most minute quantity of either element is sufficient 

 to produce its characteristic line in the spectroscope, together 

 with the fact that so many of the reagents employed in analy- 

 sis contain a trace of alkali, the indication of the spectroscope 

 is rendered misleading. While to the careful observer the 

 presence or absence of potassium is invariably revealed, all 

 evidence as to the ubiquitous element sodium is practically 

 worthless. It has, therefore, appeared advisable to us to under- 

 take the following work looking toward a method for the 

 direct determination of sodium based upon the principle of the 

 perchlorate method for the quantitative determination of potas- 

 sium. The fact that, in the form of the perchlorate, potassium 

 is insoluble while sodium is readily soluble in 97 per cent alco- 

 hol, affords a means for the separation of the two elements as 

 well as for the identification of the former. By converting 

 the sodium in the filtrate from the precipitated potassium salt 

 either to the chloride or sulphate, in which forms it is insoluble 

 in alcohol, a means for the detection of sodium is also provided. 



Assured by the experiments previously published by one of 

 us,"^ that the determination of potassium according to this 

 method would be sufficiently accurate, our experimentation was 

 directed towards determining the conditions of greatest utility 

 and delicacy for the detection of sodium. In converting the 

 sodium from the perchlorate to the chloride, attempts were first 

 made to substitute some soluble chloride for the free acid, the 

 addition of which to the alcoholic solution of sodium per- 

 chlorate, it was feared, might result in the formation of the 

 dangerously explosive compound, perchloric ether. But ani- 

 line hydrochloride, prepared by saturating a solution of aniline 

 in absolute alcohol with gaseous hydrochloric acid, when 

 applied to the precipitation of 0*010 grms. of sodium per- 

 chlorate dissolved in 5 cm^ of 97 per cent alcohol, proved 

 so hopelessly inadequate that we resorted immediately to the 

 use of free acid, which, fortunately, was found perfectly safe 



* Kreider, this Journal, vol. xlix, 448. 



Am. Jour, Sci. — Fourth Series, Yol. II, No. 10. — October, 1896. 

 19 



