ILVAITE. 143 



ness, and examined. It sometimes consists of, or con- 

 tains titanic acid. 



76. ILVAITE .* 



The finely-powdered mineral is moistened with a 

 suitable quantity of water, in a porcelain capsule, some 

 concentrated hydrochloric acid and a little nitric acid 

 added, and the whole heated to complete gelatinization. 

 The mass is then evaporated to perfect dryness on a 

 water-bath, during which operation it is frequently 

 stirred. 



The dry mass is moistened with concentrated hydro- 

 chloric acid, then dissolved in chlorine water, the 

 silicic acid filtered off', and treated in the usual man- 

 ner (No. 75). 



From the solution, diluted with the washing-water, 

 the sesquioxide of iron is precipitated by ammonia, 

 the precipitate allowed to subside in a covered vessel, 

 and rapidly filtered off; the solution should first be 

 passed through the filter, which is kept covered, as 

 far as possible, to prevent absorption of qarbonic acid. 

 The precipitate is washed by means of the wash-bottle 

 arranged for the purpose, dried, ignited, and weighed 

 as sesquioxide of iron. 



The filtrate from the sesquioxide of iron is acidu- 

 lated with hydrochloric acid, concentrated by evapo- 

 ration, in a flask, mixed with ammonia, the lime pre- 

 cipitated by oxalate of ammonia, and treated as in 

 No. 12. 



The mineral contains about 1.5 per cent, of protox- 

 ide of manganese, and 0.5 per cent, of alumina, both of 



* The compact variety from Elba is not rare. It may also be 

 obtained artificially by fusing, together 6 parts of forge-scales, 3 

 parts of fine white quartz-sand, and 1^ parts of calcined marble, at 

 a strong white heat. 



