Chemical Science. 1 W 



salt in the retort was then dissolved by water, the sulphate 6f 

 lead separated, and the manganese precipitated by carbonate of 

 potash ; this heated gave 0,282 grammes, (4,356 gr.) deut- 

 oxide of manganese, these are considered as equal to 0,261 

 prot-oxide, which were united with 0.1303 of oxygen in the acid. 



Dr. Forshhammer then states the composition of 4 oxides of 

 manganese. The sub-oxide 100 metal +20.576 oxygen; the 

 prot-oxide 100 metal +31.29 oxygen; the deut-oxide 100 

 metal +42,04 oxygen; and the per-oxide 100 metal +62.819 

 oxygen; the numbers for the oxygen being nearly as 2, 3, 4, and 6. 



The manganeseous acid consists of 100 metal, and 96.847, oxy- 

 gen, which is nearly as the number 9. But Dr. Forshhammer thinks 

 that from the action of water, ^c, the green ehamseleon already 

 contains a small portion of manganesic acid, and that the man- 

 ganesite of potash in solution is, when pure, of a blue colour; a 

 colour sometimes obtained in preparations of chamseleon. In this 

 case the proportion of oxygen would be less, and is placed by 

 Dr. Forshhammer at 8. 



The manganesic acid was thus analyzed. A solution of green 

 manganesite of potash was made, and converted by carbonic 

 acid into manganesiate, in doing which 136 of deut-oxide fell. 

 The manganesiate was decomposed by alcohol, and gave 214 of 

 deut-oxide. In the preceding analysis ,282 deut-oxide, +,1093 

 oxygen, gave manganeseous acid; hence ,136+,214=:,350 

 deut-oxide would have ,1354 oxygen in the acid of the green 

 manganesite used above ; and this same quantity of oxygen, with 

 the ,214 of deut-oxide, would exist in the red manganesiate after 

 the action of the carbonic acid. The ,214 equals ,1506 manga- 

 nese, and ,0634 oxygen, which, added to the other quantity of 

 oxygen, gives ,1988. Hence manganesic acid is composed of 

 100 metal +132 oxygen, which approaches to the number 12; 

 and considering the difficulty of the analyses, and small quan- 

 tities of the substances, may be considered a near approximation 

 to the truth. 



6. On the Ferro-prussiafes.--^M* Berzelius, in a letter to 

 M. BerthoUet, says, that in the ferro or ferrugineous prussiates, 



N 2 



