144 Dr TURNER'S Chemical Examination 



manganese by heat, was mixed with a sixth of its weight of 

 powdered charcoal, and exposed to a white heat for half an hour. 

 The protoxide thus formed was dissolved by muriatic acid, the 

 solution evaporated to dryness, and the residue kept for some 

 time in a state of fusion at a red heat. The resulting chloride 

 of manganese was re-dissolved by distilled water ; and after be- 

 ing filtered, was found to contain no impurity except a little 

 lime, which was separated by the oxalate of potash. The man- 

 ganese was then precipitated by a solution of the bi-carbonate 

 of potash, and the carbonate of manganese was carefully edul- 

 corated and collected on a filter. After removing the upper 

 layer which had become rather brown by exposure to the air, 

 the white,. carbonate was kept in a vacuum along with a ves- 

 sel of sulphuric acid until it became quite dry. The salt thus 

 prepared yielded a colourless solution, without any residue, when 

 put into dilute sulphuric acid, and was therefore free from the 

 red oxide of manganese. 



Of this carbonate 8*805 grains were heated to redness in a 

 green glass tube, and the water collected in a tube filled with 

 fragments of the chloride of calcium. The quantity of water 

 procured in this way amounted to 0742 of a grain, equivalent to 

 8'427 per cent. 



The proportion of carbonic acid was estimated by noting the 

 loss of weight which the carbonate of manganese experiences 

 when dissolved in dilute sulphuric acid. This mode of analysis, 

 as commonly performed, is inaccurate ; because the liquid retains 

 carbonic acid in solution, while the gas during effervescence car- 

 ries off with it an appreciable quantity of watery vapour. But 

 when performed with the precautions which I adopted, it yields 

 uniform results, and is susceptible of great precision. A known 

 quantity of the carbonate is placed in a small glass phial fitted 

 with a tight cork, in which two tubes are inserted. One of these 

 tubes descends to near the bottom of the phial and then bends 



