MANGANESE. 37 5 



Now, 3*8103 approaches nearly to 4 atoms of 

 oxygen from which it would appear, that man- 

 ganotis acid is a compound of 1 atom manganese 

 and 4 atoms oxygen ; and that its atomic weight 

 is 7*5. But Dr. Forchhammer concludes (though 

 I do not see the force of his reasoning), that, in 

 reality, manganous acid contains only 3 atoms of 

 oxygen, united to 1 atom of manganese. Its 

 atomic weight, on that supposition, will be 6%5. 



Dr. Forchhammer's process of experimenting And man- 

 and reasoning, by which he made out the com- 

 position of manganesic acid, is very ingenious, 

 but rather abstruse. I shall endeavour to lay a 

 simple view of it before the reader : Through 

 a solution of manganite of potash, he passed a 

 current of carbonic acid gas. By this process 

 the manganite was converted into manganate 

 of potash ; while, at the same time, 0-136 

 parts of deutoxide of manganese were thrown 

 down. The manganate was then decomposed* 

 by means of alcohol ; 0*214 parts of deutoxide 

 of manganese were 'precipitated. Now, by the 

 first process, the manganesic acid formed con- 

 tained all the oxygen in the manganous acid, 

 except what remained in the portion of the deu- 

 toxide separated. The whole deutoxide separat- 

 ed was 0-136 + 0-214 = 0-350 ; and this was the 

 quantity of deutoxide contained in the manga- 

 nous acid. The manganesic acid contained 

 only 0-214 parts ; and with these 0-214 parts 



A a I 



