146 Dr TURNER'S Chemical Examination 



to the acid and base, corresponds exactly with the analysis of 

 Dr THOMSON, as mentioned in his First Principles of Chemistry. 

 (vol. ii. p. 350.) It differs considerably from the proportions 

 stated by Dr FORCHHAMMER. (Annals of Philosophy, N. S. vol. i. 

 p. 54.) According to this chemist 33'05 parts of carbonic acid 

 combine with 51755 parts of the protoxide of manganese, a pro- 

 portion which would fix 34'45 instead of 36 as the equivalent of 

 the protoxide. This estimate is certainly erroneous ; and Dr 

 FORCHHAMMER appears to have fallen into the mistake by sup- 

 posing that the carbonate of manganese is converted by a red 

 heat into the deutoxide, whereas according to my experiments 

 the red oxide chiefly is then generated. 



It appears doubtful whether the water found by analysis in 

 the carbonate, after being dried in vacuo with sulphuric acid, is 

 mechanically retained by it or is in a state of chemical union. As 

 the proportion is not atomic, it is probable that the carbonate is 

 really anhydrous. If the ratio were as 58 to 4'5 instead of 5'337, 

 the salt might be regarded as a compound of two equivalents of 

 the carbonate of manganese and one equivalent of water. 



Composition of the Sulphate of Manganese. 



The most recent analyses of the sulphate of manganese are 

 by Dr FORCHHAMMER and Dr THOMSON, described in the works 

 already quoted. Dr FORCHHAMMER precipitated the acid of a 

 known quantity of the neutral sulphate of manganese by the ni- 

 trate of baryta, and inferred from the weight of the precipitate, 

 that 100 parts of the sulphate of manganese are composed of 

 54'378 parts of sulphuric acid and 45'622 of the protoxide. Ac- 

 cording to this analysis, the atomic weight of the protoxide is 

 33*56, a number which is surely very far from the truth, and is 

 inconsistent with the equivalent of that oxide derived from Dr 

 FORCHHAMMER'S own analysis of the carbonate. 



Dr THOMSON analyzed the sulphate of manganese by mixing 



