310 FERROCYANIDE OF POTASSIUM, ETC- 
coloured salt containing cobalt, appeared after some time 
reddish-brown. 
With respect to a method which has been proposed for 
separating quantitatively manganese from cobalt, I will cur- 
sorily observe that protochloride of manganese, according 
to my observation, is perceptibly volatilized when heated 
in a current of hydrogen gas. The hydrogen acquires the 
property of burning with a white luminous flame, which 
deposits brown stains of oxide of manganese on a cold piece 
of porcelain. Water through which the gas was passed 
gave distinct traces of protochloride of manganese. The 
salt could not have been carried over mechanically, as it 
was used in the fused state. I have moreover obtained the 
protochloride of manganese sublimed in colourless, extreme- 
ly light laminae; the heat required, however, is very great. — 
Chem. Gaz*,from Liebig's Jlnnalen. 
ART. LXIX.— ON THE ACTION OF FERROCYANIDE OF POT^ 
ASSIUM ON THE TARTRATE AND CITRATE OF IRON; 
AND OF TARTARIC ACID SIMULTANEOUSLY WITH AM- 
MONIA, ON PRUSSIAN BLUE. 
By M. Ch. Calloud. 
The ferrocyanide of potassium, of which the action on 
all the salts of iron with mineral acids is so well known 
and so well characterized, presents, in its contact with some 
salts of iron with organic acids, differences of action which 
are modified according to the state of neutrality of these 
salts, in giving products which do not appear to be isomeric 
with those of the inorganic iron salts. In examining the 
action of the ferrocyanide of iron on the tartrate and citrate 
