FROM ORTHOCLASE FELDSPAR WHYTE 149 



In making a determination of potassium both the chlor- 

 platinate and the newer perchlorate methods were followed. 

 All things considered the results showed fair agreement. The 

 only reagent it was necessary to prepare was the chlorplatinic 

 acid. This was made by dissolving some scrap platinum in 

 aqua regia. From time to time small amounts of concentrated 

 hydrochloric acid were added but the platinum went into solu- 

 tion very slowly. The digestion required two or three days. 



Experimental Results. — Two series of experiments were carried 

 on, one with carbon dioxide, the other with sulphur dioxide. 

 Considerable difficulty was met with from the presence of iron. 

 Efforts were made to meet this nuisance by lining the retort 

 with smoke-stack varnish, which helped in some degree but in- 

 troduced more or less organic matter. In working out the deter- 

 mination the iron was removed by ammonia, which made it 

 necessary to determine the potash as a chloride after removing 

 the ammonium salts by ignition, while the organic matter 

 was removed partly by filtering and partly by ignition. This 

 made the process of determination rather long. The following 

 is a table of results. The amount of K2 O shown is the percentage 

 of the orthoclase, not of its potash content. The latter figure 

 may be obtained, approximately, by removing the decimal 

 point one place to the right. 



Weight of Treatment Time Result Remarks 



Sample (grama) 



8.3908 Heat~& agitation (boiling) 2H hrs. Unchanged 



1.5212 " " " 4 " " Traces oHron 



16.1080 CO2 & steam, atmos. press. 6 " .158%K2 



13.2200 CO2 & intermittent boiling, " 4 '[ .1%%''^ Little Iron 



12.5794 CO2 no heat, pressure advanced 2 " .161% " Little Iron 



15.4311 C02lnterm't boiling, •• " 2}4 " .458%" Little Iron 



60.5300 •• no heat. Pressure 50 lbs. 2 " .090%K2 O 



52.3200 5 " none 



28.6770 " intermittent heating by 



steam, pressure 100 lbs. 10 " .I45%K2'0 More iron 



19.7476 CO2 sintered feldspar for '^ hrs 



superheated steam, 1 00 lbs. 5 " .224%K2 O 



2.3964 SO2 and boiling 1 hr. .376%KrO residue dark 



2.6800 2 hrs. .396 



3.2020 4 •• .385 



15.0214 4 " .334 



21.0526 SO2 sintered feldspar superheat- 

 ed steam. 1 00 lbs. press. 2 " .300 



