of the Oxides of Manganese. 145 



slightly upwards, so as to admit of the acid being gradually intro- 

 duced without affording an exit to the gas. The other commu- 

 nicates with a tube filled with chloride of calcium, over which all 

 the carbonic acid gas passes before escaping into the air. As 

 soon as the effervescence has ceased, the carbonic acid retained 

 by the solution is driven off by causing it to boil during the 

 space of a few minutes ; and the gas is by the same means ex- 

 pelled from the interior of the phial, into which on cooling the 

 atmospheric air is admitted by the tube for introducing the sul- 

 phuric acid. The carbonic acid gas remaining with the chloride 

 of calcium is replaced by atmospheric air, which is introduced by 

 inhaling at one extremity of the tube while the other is open. 

 The upper part of the tube for introducing the dilute sulphuric 

 acid, when not required to be open, is of course closed with a 

 cork in order to avoid loss by evaporation. 



It was found by means of the preceding process that 20*68 

 grains of the carbonate, when dissolved in dilute sulphuric acid, 

 lose precisely 7' 18 grains, or 3472 per cent of carbonic acid. It 

 is accordingly composed, in 100 parts, of 



Protoxide of Manganese .;..:. 56'853 



Carbonic Acid 34720 



Water > . > , . .. 8*427 



100-000 



Regarding 22 as the equivalent of carbonic acid, we have the fol- 

 lowing proportions : As 3472 : 56'853 : : 22 : 36'024. 



According to this analysis, 36 may be safely adopted as the 

 combining proportion of the protoxide of manganese ; and pre- 

 suming the elements of this compound to be in the ratio of one 

 equivalent of oxygen to one equivalent of metallic manganese, 

 28 will be the equivalent of the latter. This result, with respect 



VOL. XI. PART t. T 



