SEPARATION OF THE IRON AND MANGANESE. 295 



washed several times, dried, ignited in the boat, and 

 weighed in the glass tube. There should be no change 

 of weight, and a drop of oxalate of ammonia should 

 give no precipitate in the washings if the alumina was 

 pure. In the case of a precipitate a diminution of 

 weight in the alumina would be found at the same time. 

 The alumina is washed, dried, and weighed. The last 

 weight obtained is taken for the definite weight of the 

 alumina, and the difference from the first weight di- 

 vided by two gives the weight of the lime (CaO = 28, 

 CaCl = 56). 



To verify this weight, all the lime contained in the 

 washings is precipitated by oxalate of ammonia, ignited, 

 weighed, and this gives directly the weight of the lime. 



To determine by difference the quantity of iron and 

 manganese which exists in the material at the same 

 time with the alumina, we take from the entire quan- 

 tity used for analysis : 1st, the weight of the pure 

 alumina; 2d, the weight of the lime; the difference 

 gives the weight of the mixture of iron and manga- 

 nese. 



Separation of the Iron and Manganese. 



If the substance does not contain manganese, or if 

 it is not necessary to determine the manganese sepa- 

 rately, the analysis of the material insoluble in nitrate 

 of ammonia is finished. But if the iron and the man- 

 ganese are to be separated, recourse may be had to the 

 following method : 



Into a platinum tube a current of vapor of water, 

 furnished by a retort containing distilled water and a 

 few drops of hydrochloric acid, is passed. This vapor 

 will be condensed in the tube, and will take with it 

 into the flask or globe all the chloride of iron and man- 

 ganese produced by the evaporation. This washing 

 done, the waters are placed in a small crucible, and 

 a few drops of sulphuric acid added, evaporated to 



