Identification of Potassium, and Sodium. 



265 



appeared evident that smaller quantities could be detected with 

 certainty, a solution of the salt containing 0*050 grms per 100 

 cm^ of water was used, and each |)ortion evaporated to dryness 

 before adding the alcohol. In each case the alcohol subsequent 

 to its addition was saturated with gaseous hydrochloric acid^ 

 being kept cool by immersion in a beaker of water. For the 

 generation of hydrochloric acid, the well known form of appa- 

 ratus consisting of a side neck flask, containing sodium chloride 

 covered with hydrochloric acid fitted with a stoppered funnel, 

 through which sulphuric acid could be admitted as desired, 

 served admirably. 



It is evident, then, that by the use of 10 cm^ of 97 per cent 

 alcohol with gaseous hydrochloric acid 0-0003 grms. of sodium 

 oxide can be found with certainty ; and when the alcohol is 

 allowed to become saturated with the gas even 0*00006 grms. 

 of sodium oxide will be unmistakably revealed. The quantity 

 of alcohol, 10 cm^, is sufficient for all purposes, since this 

 amount will dissolve about two grams of sodium perchlorate ; 

 but even in 40 cm^ 0*0002 grm. of sodium oxide may be seen 

 distinctly ; from which fact it is evident that this method can 

 be applied to the quantitative determination of sodium. Abso- 

 lute alcohol does not materially increase the delicacy of the test. 



In Table II are recorded the results of experiments made 

 upon mixtures of the two elements. The sodium and potas- 

 sium taken were drawn from separate standard solutions con- 

 taining one gram of the purified perchlorates in 100 cm^ of 

 distilled water. After evaporating to dryness on the steam 

 bath, the residue was treated with the usual amount of 97 per 

 cent alcohol, the insoluble potassium perchlorate was removed 

 by filtering through a dry paper filter and dry funnel into a 

 dry test tube, and the filtrate saturated with gaseous hydro- 

 chloric acid. 



Table II. 



I 



KCIO4 



taken. 



grms. 



0*0500 

 0*0200 

 0*0100 

 0*0050 

 0*0040 

 0*0030 

 0*0020 

 0-0010 

 0*0005 

 0*0003 

 0*0001 

 0-0000 

 0-0100 



K20 



equivalent, 

 grms. 



0*01699 

 0*00680 

 0-00340 

 0*00170 

 0*00136 

 0*00102 

 0-00068 

 0*00034 

 0*00017 

 0*00010 

 0*00003 

 0-00000 

 0*00340 



NaC104 

 taken, 

 grms. 



0*0500 

 0*0200 

 0*0100 

 0-0050 

 0*0040 

 0*0030 

 0*0020 

 0*0010 

 0*0005 

 0-0003 

 0*0001 

 0*0100 

 0*0000 



NasO 



equivalent. 



grms. 



0*01250 



0*00500 



0*00250 



0*00125 



0*00100 



0-00075 



0-0005 



0*00025 



0*00012 



0*00007 



0-00003 



0*00250 



0*00000 



Indication 



for 

 potassium. 



Strong 



u 



good 



u 



trace 



(( 



faintest trace 

 none 

 strong 



Indication 



for 



sodium. 



strong 



good 

 (( 



« 

 trace 



none "" 

 strong 

 none 



