414 



Dr. Thomas Thomson on the 



bonic acid occasioned by this is about made up by the mois- 

 ture which the carbonic acid gas carries off along with it. 

 This renders the error in general trifling. 



It will be proper to subjoin an example or two of the 

 method of proceeding, to enable the reader to judge of the 

 goodness of this test, and its value to the manufacturer. 



The black oxide of manganese employed was subjected 

 to analysis, and found composed of 



Binoxide of manganese 68*49 



Peroxide of iron .... 11*85 



Loss of weight 32-5 grains. It ought to have been 34*245 

 grains. Error 1*745 grains. 



Loss of weight 34*5 grains. It ought to have been 

 34*245 grains. Here the error is in excess, and amounts 

 to 0*255 grains. 



Experiment 3. 

 Put into the flask — Water . . 

 Oxalic acid . 

 Black oxide 

 Sulphuric acid 



Total . 



600 grs. 



75 



50 

 154*1 



879*1 



