274 On the Oxidant Mmganoso-Manganicum. [April, 



tube, which was filled with pure carbonate of manganese, and a 

 current of muriatic acid gas was passed through it. The extri- 

 cation of gas took place without any evolution of heat till the 

 salt appeared completely decomposed. The salt was now 

 heated by a spirit-lamp at first slowly, but at last the greatest 

 possible degree of heat was given. The muriate thus formed 

 was rose-red, and it retained its colour, though the muriatic acid 

 gas driven over was at last mixed with hydrogen gas. The salt 

 thus obtained weighed 1*52 gramme. Being dissolved in water 

 there remained behind 0*012 gramme of oxide of manganese. 

 The remaining 1*508 was a neutral salt. The solution was quite 

 colourless. The muriatic acid was thrown down by nitrate of 

 silver, and gave, after the usual treatment, 3*408 grammes of 

 horn silver, which contains 0*650 gramme of muriatic acid. 

 This acid was combined with 0*858 gramme of protoxide of 

 manganese; but 0*65 muriatic acid saturate a quantity of base, 

 whose oxygen amounts to 0*191 ; consequently the 0*858 

 gramme of protoxide and manganese contain this quantity of 

 oxygen. The experiment gives us 100 parts composed of 



Manganese 77*856 100*00 



Oxygen 22*144 28*44 



100*000 128*44 



John, by direct analysis of neutral sulphate of manganese, 

 found the protoxide of this metal to contain 21*875 per cent, of 

 oxygen. The oxygen, according to my experiment, is a little 

 more ; but I have reason to conclude that a small quantity of 

 black oxide existed in the muriate of manganese which I 

 examined. The result of my experiment, therefore, may, per- 

 haps, be the less to be depended on. 



Appendix. 



That the English reader may fully understand the preceding 

 paper, a few observations may be necessary. 



1. The atomic weight of manganese is 3*5, and the atomic 

 weight and constituents of its oxides are as follows : 



Composition. 

 Atomic weight. Metal. Oxygen. 



1. Suboxide . 4*0 . ... 3*5 + 0*5 



2. Protoxide 4*5 3*5 + 1*0 



3. Deutoxide 5*0 . ... 3*5 + 1*5 



4. Tritoxide 5*5 3*5 + 2-0 



5. Manganesous acid. . 6*5 .... 3*5 + 3*0 



6. Manganesic acid. . , 7*5 . , , . 3*5 + 4*0 



