Gooch and Newton — Method for the Estimation of Iron. 367 









Table II. 







Ferric 



Sulphate 



cm 3 



Ti0 2 

 grm. 



KMn0 4 

 cm 3 



Taken 



Fe 2 3 

 Found 



Error 



10 



0'04 



12-84 



0-0993 



0-0992 



— 00001 



10 



0-06 



12-85 



0-0993 



0-0993 



±0-0000 



10 



0-08 



12 90 



0-0993 



0-099.7 



+ 0-0004 



10 



O'l 



1290 



0-0993 



0-0997 



+ 0-0004 



10 



o-i 



12-89 



0-0993 



0-0996 



+ 0-0003 



10 



o-i 



12-85 



0-0993 



0-0993 



±00000 



10 



o-i 



12-80 



0-0993 



0-0989 



— 0-0004 



10 



o-i 



12 90 



0-0993 



0-0997 



+ 0-0004 



10 



0-2 



12-90 



0-0993 



0-0997 



+ 0-0004 



10 



0-2 



12-89 



0-0993 



0-0996 



+ 0-0003 



10 



0-2 



12 90 



0-0993 



0-0997 



+ 0-0004 



20 



o-i 



25-70 



0-1986 



0-1986 



±0-0000 



form of reductor recommended by Blair.* The receiving- 

 flask was kept cool in running water, a small amount of bis- 

 muth oxide added, the flask shaken and allowed to stand a 

 few minutes, and filtration made with the aid of the suction 

 pump. In the cold solution free from dissolved, oxygen there 

 is little danger of reoxidation of ferrous sulphate, as has been 

 shown by Peters and Moody. -j- 









Table III. 







Ferric 



Sulphate 



cm 3 



Ti0 2 

 grm. 



KMn0 4 

 cm 3 . 



Taken 



Fe 2 O s 

 Found 



Error 



40 



o-oi 



46-80 



0-3943 



0-3943 



±0-0000 



40 



0-02 



46-79 



0-3943 



0-3942 



—o-oooi 



40 



0-04 



46-80 



0-3943 



0-3943 



±0-0000 



40 



0-06 



46-83 



0-3943 



0-3946 



+ 0-0003 



40 



o-i 



4675 



0-3943 



0-3939 



— 0-0004 



40 



01 



46-82 



0-3943 



3945 



+ 0-0002 



40 



o-i 



46-78 



0-3943 



3941 



— 0-0002 



40 



o-i 



46-80 



03943 



0-3943 



±0-0000 



40 



o-i 



46-75 



0-3943 



0-3939 



— 0-0004 



40 



o-i 



46-80 



0-3943 



0-3943 



±0-0000 



40 



0-2 



46-77 



0-3943 



0-3940 



— 0-0003 



40 



0-2 



46-81 



0-3943 



0-3944 



+ o-oooi 



40 



0-2 



46-85 



0-3943 



0-3947 



+ 0-0004 



These results show plainly that the ordinary process of 

 reducing ferric salts by means of -zinc, either in the flask or in 

 the reductor, may be made applicable in presence of titanium 

 compounds by adding copper oxide or preferably bismuth 

 oxide to the reduced solution and filtering before titrating 

 with potassium permanganate. 



* Loc. cit. f This Journal, xii, 367. 



