D. U. Hill — Separation of Potassium and Sodium. 77 









Table II. 









KC1 taken 



KC10 4 



Error on 



NaCl taken 



NaCl 



Error on 





grm. 



found 



K 2 



grm. 



fonnd 



Na 2 







grm. 



grm. 





grm. 



grm. 



(1) 



0*0500 



0-0932 



+ 0-0001 



0-0500 



0-0496 



— 0-0002 



(2) 



0-0400 



0-0729 



— 0-0005 



0-0400 



0-0392 



— 0-0004 



(3) 



0-0400 



0-0727 



— 0-0006 



0-0400 



0-Q393 



— 00004 



(4) 



0-0400 



0-0728 



— 0-0006 



0-0400 



0-0394 



— 0-0003 



(5) 



0-0300 



0-0558 



o-oooo 



0-0300 



0-0293 



— 0-0004 



(6) 



0-0300 



0-0556 



—o-oooi 



0-0300 



0-0295 



— 0-0003 



(?) 



0300 



0-0543 



— 0-0005 



0-0300 



0-0295 



— 0-0003 



(8) 



0-0300 



0-0540 



— 0-0006 



0-0300 



0-0296 



— 0-0002 



mental results indicate the presence of a small constant nega- 

 tive error due apparently to some solubility of sodium chloride 

 in the saturated solution of hydrogen chloride in alcohol, as 

 well as to losses in manipulation. Unfortunately the error per 

 cent cannot be lessened by working with larger amounts of the 

 salts on account of the limited solubility of the chlorides in 

 alcohol. 



During the past two years the methods described above for 

 precipitating potassium by aniline perchlorate, and then sodium 

 chloride by hydrochloric acid gas, have been successfully used 

 as a means of detecting the presence of these elements by the 

 class in qualitative analysis in this laboratory. In order to 

 lessen the amount of gaseous hydrogen chloride used, the 

 sodium, after the removal of the potassium, is precipitated by 

 means of sulphuric acid instead of hydrogen chloride, where 

 possible. A few drops of a dilute solution of sulphuric acid in 

 alcohol will generally precipitate even very small amounts of 

 sodium as sodium sulphate, but if too much acid is added the 

 acid sulphate is formed and dissolved in the alcohol. Hence, 

 if 110 precipitate is obtained with sulphuric acid, gaseous hydro- 

 gen chloride is passed into the solution to saturation, precipita- 

 ing the sodium as chloride practically completely. 



