Chemistry. XXXVil 
considerations. I am not disposed to change them till it has 
been shown in a satisfactory manner that they are inconsistent 
with experiment. The proportion of oxygen which I have given 
differs only about ,',th part from that given by Berzelius. Now 
Iam very much afraid that the limits of unavoidable error in such 
experiments are greater than th of the whole. Hence we have 
no means of coming at the truth except by theoretic views, 
which will guide us to new experiments ; and when these are 
sufficiently multiplied, we shall obtain a mean approaching very 
near the truth. 
M. Arvedson, during his experiments, made a discovery of 
rather an interesting nature, and deserving the attention of the 
manufacturers of the bleaching salt and bleaching liquor. He 
found that there are two native black oxides of manganese. The 
first, the common peroxide; the second, the hydrated black 
oxide, which he found composed as follows : 
Oxidum manganoso-manganicum ........ 89-92 
TY AUCEL aires een wen pal Hl BOSE ESS -. 10:08 
100-00 
This oxidum manganoso-manganicum is a compound of two 
atoms of peroxide and one atom of protoxide of manganese ; or 
it contains ;th less oxygen than the peroxide. If the oxygen in 
the water be added to that of the oxidum manganoso-mangani- 
cum, the whole will be converted into peroxide of manganese.— 
(Jour. de Phys. Ixxxvii. 464.) 
There is reason to believe from the late experiments of Chevil- 
lot and Edwards, that manganese is capable of combining with 
an additional atom of oxygen, and of forming a new compound, 
which seems to possess acid properties, and to act with great 
energy on combustibles. They have not yet given us the pro- 
portions of manganese and oxygen which exist in this compound ; 
but they have shown that red chameleon mineral is a compound 
of potash, black oxide of manganese, and oxygen, which are all 
present in definite proportions ; that the quantity of oxygen 
depends upon that of the manganese present, and not upon that 
of the potash ; that the combination is neutral, and possesses the 
characters of a salt ; and that when an excess of potash is added, 
the chameleon assumes a green colour. When these crystals 
are heated in contact with hydrogen gas, they set it on fire. 
They detonate violently with phosphorus, set fire to sulphur, 
arsenic, and antimony, and indeed to all combustible bodies 
hitherto tried. Were we to suppose this manganesic acid (as 
Chevillot and Edwards have termed it) a compound of one atom 
manganese and three atoms oxygen, its constitution would be 
as follows : 
Manganese. ..,. 3°5. ........ 100:00 
PROM 5 eit 05 BIO! I ais a GDL 
