588 DISTINCT CRYSTALS OF MANGANATE OF POTASH. 
last term, because the sulphate of iron had in ' with the air, as Edwards and Chevillot 
created the quantity of oxygen absorbed, we have already shewn. But the green com- 
obtain pound may be obtained equally well, when 
Azotic gas .. .. 80-32 volumes. the binoxide of manganese is ignited with po- 
Oxygen "as .... l9 63 ,, tash in a retort shut up from the aii. Thus 
" ** ” lO grammes of binoxide of manganese, heated 
lOO-OO 
Now this differs very little fiom the compo- 
sition of air. If we analyze air without remov- 
ing previously the carbonic acid gas and the 
moisture which it contains, we always find 
the volume of its oxygen below 20 per cent. 
CTo be continued.) 
ON MANGANIC AND HYPKRMAN- 
GANIC ACIDS, ON HYPFRCHl.O- 
RIC ACID, AND THE SALTS OF 
IHESE ACIDS. 
By E. M itscherlich.* 
Scheele first observed a part of the pheno- 
mena, which, as I shall immediately show, 
are produced by two acids foimed from man- 
ganese ; and after him chemists of eminence 
have repeatedly turned their attention to the 
subject. Chevreui, Chevillot, and Edwards, 
Forchhammer, Fromheiz, and U nverdorben, 
have added mote or less interesting facts to 
those pieviously known, although they have 
by no means exliausted the subject. 'I he-e 
compounds, however, would unquestionably 
have been long ago completely investigated, 
had not the great difficulty of obtaining the 
pure acid in sufficient quantity rendered their 
examination almost an impossibility. I'hey 
are decomposed very easily by a great num- 
ber of circumstances ; their solutions cnunot 
be filtered, nor their crystals laid upon paper, 
because they are instantaneously decomposed 
by organic substances. 
Very distinct crystals, which 1 obtained of 
manganate of potash, enabled me to deter- 
mine their shape, and as it was found to agree 
in every respect with that of the chromate, 
seleniate, and sulphate of potasii. this circum- 
stance, which is particularly interesting in the 
elucidation of the connexion of the crystalline 
shape of bodies with their composition, indu- 
ced me to investigate more closely these acids 
and their compounds. 
I.-ON THE ACTION OF POTASH 
ON THE BINOXIDE OF MANGA- 
NESE. 
When equal parts of potash and binoxide 
of manganese are ignitedtogether, and the igni- 
ted mass treated with water, a green solution 
is obtained, which contains in solution, 
carbonate of potash, caustic potash, and a 
compound of potash with manganese in 
a higher degree of oxidation, wliile a brown 
powder remains undissolved. Oxygen is ab- 
sorbed when the mass is ignited in contact 
• Poggendorff’s Ann., xxv., '2H7. (The pub- 
lication of this interesting paper is rendered 
necessary to illustrate that of Dr.Clark, print- 
ed in Records, vol. iii. 433, and vol. iv. ‘la. 
— Edit.) 
with potasli without the access of air, and 
treated with water, gave a solution, which, 
when the acid was decompostul, and the man- 
ganese precipitated and ignited, yielded 1 
gramme of the red oxide (oxidum mangaaeso- 
maaganesicum.) 
In this case, the higher degree of oxidation 
of tJie manganese is produced in the same 
manner in whicii the biovvn oxide of lead is 
formed from red lead, when the latter is treat- 
ed with nitric acid, and the brown residue 
wiiich is left, when the green compound is 
dissolved, consists of hydrated sesqui and hi- 
noxides of manganese, but whether mixed or 
chemically combined, 1 cannot venture to 
decide. I'lie manganic acid is formed by a 
pail ot the binoxide giving up a portion of ils 
oxygen to the remainder , by vvliicb it is chang- 
ed to stsquioxide, but the quantity of manga- 
nic acid tormed, sliows that a poition of tlie 
binoxide remains undecomposed. 
If we pour off the deep green solution, after 
allowing the brown insoluble poition to sub- 
side. and allow it toevapoiale over sulphuric 
acid, under the exhausted receiver of an air 
pump, we obtain beautiful pure crystals of 
a gieen colour, mixed with abundance of 
crystals of hydrate and carbonate of potash. 
I'hese crystals must be laid on poious tile or 
clay, which absorbs the moisture without 
producing decomposition. If the solution be 
allowed to evaporate in contact wiili the at- 
mospbere, red crysiltals, the composition of 
which I shall attend to afterwards, may be 
formed by ibe action of the caibonic acid of 
the air. 
If the green crystals be treated with water, 
a red solution is obtained, wliich, by evafjora- 
tion, yields red crystals. I'he green crystals 
consistoi manganateof potash, whicli is isomor- 
phous with sulphate ol potash, while the red 
liave tiie same form as the peichlorale of po- 
tash. Accurate analyses have shown that 
botli the perchloric acid and the highest degree 
of oxidation of magnanese, contain 7 propor- 
tions of oxygen. It appears to me, therefore, 
to be convenient to denominate that degree of 
oxidation of manganese which corresponds 
with sulphuric, seienic, and chromic acids, 
licid, while the highest degiee of 
oxidation ol manganese may be called hyper~ 
rniin^anic add, and that of chlorine hyper- 
chloric acid, following the nomenclature of 
Gay Lussac with respect to /ir/po-sulphuric 
acid.^ 
( To he contimied.) 
t la this investigation I have been greatly 
aided in the preparation of the substances 
by my assistant, .Vi. WolfiF, a very skilful phar- 
maceutist. 
