374: Gooch and Havens — Volatilization of Iron, etc. 



gas was made by dropping sulphuric acid into strong hydro- 

 chloric acid mixed with salt, and a little manganese dioxide 

 was added when the mixture with chlorine was desired. The 

 experimental details are given in the table. 



Fe a O s 



taken. 



grin. 



o-iooo 



0*2000 

 0-1020 

 0*2145 



0-1000 



o-iooo 



0-1072 

 0-2045 

 0-1050 

 0-2008 



A1 2 8 



taken. 



0-1015 



0-1006 



0-1032 

 0-1013 

 0-1032 

 0-1023 

 0-1007 

 0-1087 



A1 2 3 



found. 



grm. 



0-1015 

 0*1008 



0-1032 

 0*1015 

 0-1033 

 0-1019 

 0-1006 

 0-1087 



Error, 

 grm. 



o-oooo 



0-0000 



o-oooo 



+ 0-0002 



0-0000 



0-0000 



+ 0-0002 



+ 0-0001 



— 0-0004 



—o-oooi 



O'OOOO 



Time, 

 hours. 



* 



1 

 l 



3. 

 4 

 3. 



4 



1 



1 

 "2 

 3 

 4 



Temperature. 

 C°. 



450-500 



a 



180-200' 



450-500 



Atmosphere. 

 HC1. 



HC1 + CL. 



The residual alumina tested in several experiments by fusion 

 with sodium carbonate, solution in hydrochloric acid, and addi- 

 tion of potassium sulphocyanide gave no indication of the 

 presence of iron. 



The separation of the iron is obviously complete at 450° to 

 500° when the mixed oxides are submitted at once to the action 

 of hydrochloric acid gas, or at 180° to 200° when chlorine is 

 mixed with the hydrochloric acid. Plainly, the extremely 

 high temperatures employed by Deville are unnecessary if the 

 mixed oxides are submitted at once to the action of hydrochloric 

 acid at 450° to 500° without previous gentle heating in the acid 

 atmosphere. We prefer, however, to use the mixture of 

 chlorine and hydrochloric acid, not only because the tempera- 

 ture of the reaction is lower, but because it needs no regula- 

 tion, while the danger of error arising from the liability of 

 ferric chloride to dissociate, or from deficiency of oxidation in 

 the oxide treated, or from mechanical loss due to too rapid 

 volatilization, is avoided. 



