1815.] a Chemical Knowledge of Manganese. 275 



appear that the carbonate contains 1 atom, the sulphate 9, the 

 sulphite 4, and the muriate 8 atoms. 



It was first observed by Richter that when one metal is preci- 

 pitated from a solution' by another the solution continues as 

 neutral as at first. In this case the metal is changed, but the 

 acid and the oxygen remains unchanged. For example, if we 

 have a solution of sulphate of copper, a plate of zinc introduced 

 throws down the copper. The copper in the solution was united 

 with a certain proportion of oxygen and sulphuric acid ; the 

 zinc which has taken its place is now dissolved with the very 

 same oxygen and sulphuric acid ; so that the sulphuric acid 

 now neutralizes a quantity of zinc containing just the same 

 quantitv of oxygen that the copper did which it formerly neu- 

 tralized. From this it follows that acids (as far at least as those 

 metals are concerned which throw down each other) always 

 neutralize portions of oxides containing the very same numerical 

 quantity of oxygen. 



It has been ascertained that the quantity of oxygen in the 

 oxides neutralized by 100 parts of the preceding acids is as 

 follows : — 



Carbonic acid 36'68 



Sulphuric acid 20-02 



Sulphurous acid 20 02 



Muriatic acid 30-49 



Now the quantities of protoxide of manganese, which contain 

 these respective numbers of oxygen, are the following : — 



36*68 oxygen are contained in 297'68 protoxide 



20-03 162-47 



20*02 162-47 



30-49 247-45 



If we compare these numbers with the composition of the 

 salts as contained in Dr. John's paper, we shall find that the 

 rule by no means holds with respect to the salts of manganese. 

 According to his analysis, 



100 carbonic acid saturate 16:! - 46 protoxide 



100 sulphuric acid 92*10 



100 sulphurous acid .... 105-87 

 J 00 muriatic acid 192'11 



It would appear from this statement that the law ought not to 



be extended to those metals that arc not precipitated l>y others 



in the metallic state. Probably the non-existence of this law 



h respect to them is the reason why they are not precipitated. 



4. The luppoeed new metal announced by John in the pre- 



s 8 



