ELISHA MITCHELL SCIENTIFIC SOCIETY. 0/ 



the iron was made. The zirconium dioxide could not be 

 obtained perfecth' white, but possessed from a yellow 

 to a brown color due to the iron present. However, if 

 the amount of iron be small, five per cent, and less, as 

 it occurs in the mineral zircon, the separation was 

 thoroug'h and the ig'nited zirconium dioxide obtained 

 was sno^v white and iron free. 

 Two analyses are g'iven : — 



Found. Used. 



^rO.— 0.1119 0,1118 



0.2815 0.2818 



The process was as follows : To the solution of the 

 salts, tartaric acid, best solid, to five times the amount 

 of iron present, was added, and this neutralized b}^ an 

 excess of ammonium hydroxide, and then ammonium 

 sulphide in excess. This was warmed slig'htly, covered, 

 and set aside to settle. The supernatant liquid must 

 acquire a yellow color before filtration. To avoid this 

 delay, one experiment was carried out by boiling' and 

 direct filtration. Time was thereby saved. The pre- 

 cipitated iron sulphide was washed quickly with a di- 

 lute ammonium sulphide solution. The filtrate was 

 evaporated in a porcelain dish on a water bath until it 

 became of small bulk, when it was transferred to the 

 crucible, in which the final residue was to be weighed. 

 Sometimes it was noticed that there was a further sep- 

 aration of iron sulphide during- this evaporation. This 

 was filtered off before the concentration became too 

 g-reat without causing- anv error in the final result. The 

 crucible when apparentl}^ dr}^ was heated for several 

 hours in an air bath at 100 "C. and then ig-nited, top on. 

 After the volatile portion of this residue was driven off, 

 the lid was removed and all the carbon burned away. 



