280 Klaproth on the Chemical Analyiis 



litmus paper to blue, and produced fumes when brought to a 

 glass rod dipped in muriatic acid ; it occasioned a brown pre- 

 cipitate in solution of lead ; became milky when neutralized by 

 muriatic acid ; filtered and evaporated, it left 2 grains of muriate 

 of ammonia. 



c. The black residue in the retort weighed 750 grains ; its 

 charcoal was burned off and there remained 660 grains of a 

 reddish-brown matter, so that the carbonaceous loss was 90 

 grains. 



d. 132 grains of this brown residuum, (one fifth,) mixed with 

 twice its weight of caustic soda and fused, furnished a greenish- 

 brown mass which, digested in water gave a pale green solu- 

 tion ; supersaturated by muriatic acid, evaporated, and again 

 digested with water acidulated by the same acid, silica remained, 

 "weighing, after ignition, 80 grains. 



e. The remaining liquid was saturated with carbonate of 

 potassa, and the washed precipitate thus obtained boiled in 

 liquid caustic potassa to abstract the alumina, which, thrown 

 down by muriate of ammonia, washed and heated, weighed 32 

 grains. 



f. The brown residue, insoluble in the caustic alcaline solu- 

 tion, was dissolved in dilute sulphuric acid, and evaporated to 

 dryness ; during the evaporation sulphate of lime separated, 

 which was carefully collected ; it weighed rather more than 2 

 grains : the dry mass was ignited and washed, and the oxide of 

 iron, which tlien remained, being collected and mix«d with oil 

 and ignited became magnetic, and weighed 14.5 grains. The 

 washings saturated, when boiling hot, with carbonate of potassa, 

 yielded a slight trace of carbonate of magnesia. 



E. 



a. 200 grains of the ore were slowly distilled in a sand-heat, 

 60 that no gas was evolved ; 21.5 grains of water very slightly 

 sulphurous, passed into the receiver, and an extremely thin 

 .coating of sulphur was remarked in the neck of the retort. 



b. The dried ore was taken out of the retort and heated upon 

 a tile ; it exhaled a slight smell of sulphur, without either smoke 

 or fisune. Tlie los^ during tlie combustion amounted to 45 



