300 Berzelius — Analysis of a 



g. The precipitate thus treated with potash dissolved with 

 ease in diluted muriatic acid, leaving peroxide of manganese, 

 which, washed and heated to redness, weighed .081. There 

 was found, also, a trace of oxide of iron, and of thorina, but 

 too small to admit of separation. 



h. The solution in muriatic acid was neutralized by caustic 

 ammonia, and concentrated by evaporation, after which pure 

 sulphate of potash was dissolved in it to complete saturation. 

 There fell a fine white powdery precipitate, which was thrown 

 upon the filter, and washed with a saturated solution of sul- 

 phate of potash. It was then dissolved from the filter by boil- 

 ing water, which took it up without residue. The solution, 

 precipitated by caustic potash, gave a white earth, which did 

 not become yellow by washing, by which the absence of cerium 

 was shown, and which, heated to redness, weighed 2.817 

 grammes, and was thorina, with a slight, yet low, tinge, from a 

 trace of oxide of manganese, which could not be quantitively 

 separated, but the presence of which was also shown by car- 

 bonate of soda on a slip of platinum. Its quantity is, at all 

 events, too small to affect the weight of the earth, in any sen- 

 sible degree. In further trials, made upon this earth, it was 

 found free from all other mixture. 



i. The solution, precipitated by sulphate of potash, was 

 again precipitated by caustic potash, the precipitate well 

 washed, and treated afterwards with carbonate of ammonia. 

 The portion insoluble in carbonate of ammonia, heated to 

 redness, weighed .1905. It was dissolved in muriatic acid, 

 and decomposed, in the usual way, by succinate of ammonia 

 into .162 peroxide of iron, and .0285 peroxide of manganese. 



k. The solution in carbonate of ammonia was evaporated to 

 dryness. The dry mass was digested with dilute acetic acid, 

 which became of a yellow colour, and with caustic ammonia 

 gave a beautiful bright yellow precipitate, which, after washing 

 and heating to redness, became dark green, and weighed .079, 

 proving to be protoxide of uranium. 



I. The residue, after digestion with acetic acid, was yellow 

 grey with muriatic acid : it gave a colourless solution, which 

 was first mixed with tartaric acid, and afterwards supersa- 

 turated with ammonia, without the appearance of any preci- 



