858 
PEOFESSOE B. 0. BEODIE ON THE OXIDATION AND 
nese appears. The solution then becomes turbid, and the bro^^^a flocculent peroxide is 
precipitated. 
It appears therefore, (1) that the protoxide of manganese can be oxidized by the per- 
oxide of sodium to an oxide, forming a clear brown solution; (2) that permanganic acid 
can be reduned by the peroxide of sodium to the same substance, passing through the 
condition of manganate; (3) that when the reduction reaches this point, in presence of 
an excess of peroxide the reduction is for a time arrested, and the catalytic decomposi- 
tion commences : during this decomposition the brown compound is permanent ; and 
when the peroxide of sodium is nearly decomposed, the reduction again proceeds and 
peroxide of manganese is formed. 
These phenomena may be thus accounted for. There is a point where the oxidizing 
action concurs with, and as it were meets, the reducing action of the peroxide of 
sodium ; and at this point the catalysis takes place. The peroxide of manganese is 
formed; but so long as a sufficient excess of the alkaline peroxide is present, it is 
reoxidized and destroyed as fast as it is produced. By this continuous reduction and 
oxidation the peroxide of sodium is gradually eliminated. Time is needed for this, as 
for other chemical changes ; but ultimately, when but little peroxide of sodium 
remains, the peroxide of manganese is precipitated, being produced more rapidly than 
it is destroyed. 
There are other examples of the same class of phenomena. AVhen a solution of 
peroxide of sodium is added to a'solution of a copper salt (sulphate orchloride of copper), 
at first there is no evolution of oxygen, but a yellowish green precipitate is formed, as 
was observed by Thenaed ; this precipitate may be thrown on a filter, and for a short 
time preserved. If a small portion of this precipitate be added to an alkaline solution 
of peroxide of sodium, bubbles of gas are evolved, and the peroxide of sodium rapidly 
decomposed. If a solution of peroxide of hydrogen be mixed with a few di’ops of a 
weak solution of chloride of copper, and the whole precipitated by baryta water, the 
same yellow oxide of copper is formed. The peroxide of barium is gradually decom- 
posed ; but during the decomposition this yellow oxide is permanent, and only ultimately 
is it decomposed into hydrated protoxide. 
If a very small quantity of an ammoniacal solution of protochloride of copper be added 
to an alkaline solution of peroxide of sodium, the solution becomes of a yellow coloirr, 
and is gradually decomposed. During the whole time of this decomposition, which may 
be caused to extend over several hours, the yellow colour is permanent ; but ultimately, 
when the whole of the peroxide is decomposed, the blue colour of the ammoniacal solu- 
tion of the protoxide reappears. The yellow solution of the peroxide of copper, apart 
from the solution of peroxide of sodium, cannot be preserved for many minutes. The 
singular permanence of this compound during the decomposition is explained on the 
hypothesis, that it is continually reproduced as well as destroyed. In this reaction the 
solution of oxide of copper in potash or ammonia decomposes the alkaline peroxide into 
oxygen and the alkali, precisely as sulphuric acid in the process of etherification effects 
