76 D. U. Rill — Separation of Potassium, and Sodium. 



ously to expel the excess aniline with the steam before it has 

 time to darken. Colorless crystals are obtained in this way. 



Experiments were made first to determine the completeness 

 of the precipitation of sodium chloride from 97 per cent alcohol 

 by gaseous hydrogen chloride. The method was as follows : 

 O1000 grm. of purified sodium chloride was dissolved in l - 5 cmS 

 of water, 4:8"5 cm3 of absolute alcohol was added (this amount 

 of 97 per cent alcohol will not hold much more than 0*05 grm. 

 of sodium chloride in solution), and gaseous hydrogen chloride 

 (conveniently evolved by the action of concentrated sulphuric 

 acid upon massive ammonium chloride in a Kipp generator) 

 was passed into the cooled solution through an inverted funnel. 

 When the solution appeared to be saturated with the gas, the 

 precipitate was collected on asbestos in a perforated crucible, 

 dried at about 110°, and weighed. Table I shows the results 

 of these experiments: 







Table I. 









NaCl taken 



NaCl found 



E] 



•ror on NaCl 



Error on Na 2 





grm. 



grm. 





grm. 



grm. 



(1) 



o-iooo 



0-0994 





— 0-0006 



— 0-0003 



(2) 



o-iooo 



0-0989 





—o-ooii 



— 0-0006 



(3) 



o-iooo 



0-0994 





— 0-0006 



— 0-0003 



(4) 



o-iooo 



0-0992 





— 0-0008 



— 0-0004 



A series of experiments was then made in which both 

 potassium and sodium were estimated. Equal amounts of 

 recrystallized potassium chloride and sodium chloride were 

 weighed out and dissolved in l-5 cm3 of water. The amounts 

 used are shown in Table II. An excess of aniline perchlorate 

 (about "5 grm.) dissolved in 48-5 cm3 of absolute alcohol was 

 then added, and the precipitate of potassium perchlorate was 

 filtered off on a perforated crucible with the aid of suction, 

 and washed with about 20 cm3 of 97 per cent alcohol. The pre- 

 cipitate was dried at 110° and weighed. The filtrate was satu- 

 rated with hydrogen chloride from the Kipp generator as in 

 the previous experiments, the precipitate of sodium chloride 

 collected on a perforated crucible, washed with a saturated 

 solution of hydrogen chloride in 97 per cent alcohol, dried and 

 weighed. The results of this series of experiments are shown 

 in Table II. 



The errors on potassium are greater than those obtained by 

 Kreider,* who took pains to convert the potassium chloride 

 completely into perchlorate by evaporating it twice with per- 

 chloric acid to a syrup-like consistency, and in washing used 

 97 per cent alcohol containing perchloric acid, finishing with a 

 very little pure alcohol. In the case of sodium the experi- 

 * This Journal (3), xlix, 443-8, 1895. 



