382 NEW PROCESS FOR REGENERATION OF OXIDE OF MANGANESE. 
suggestions that may lead to the adoption of a bye-law more satisfactory than 
the one now in force, relating to the life members’ subscription fee. 
I am, Sir, your obedient servant, 
Henry Long. 
Croydon , January 7, 1868. 
ON A NEW MANUFACTURING PROCESS FOR THE PERPETUAL RE¬ 
GENERATION OF OXIDE OF MANGANESE USED FOR THE LIBERA¬ 
TION OF CHLORINE FROM HYDROCHLORIC ACID.* 
BY WALTER WELDON. 
Every process, previous to that to be described in the present paper, by which it has 
been attempted to regenerate oxide of manganese from the residues of the manufacture 
of chlorine, has been performed in the dry way, and has thus required considerable time, 
and has involved not only at least one—more or less troublesome and costly—furnace 
operation, but also several removals of the material from vessel to vessel and from place 
to place; every such removal, of course, entailing more or less loss of material. The 
process, however, which is about to be described is performed in the wet way, and may 
be completed, even when operating on the largest scale, within as little as one hour. 
Moreover, all the operations of the process are performed in the same vessel as that in 
which the oxide produced by it is afterwards employed to react with hydrochloric acid, and 
from this vessel or still the manganese is never removed, so that it is entirely free from 
risk of loss by removal; and as it is not subject to any other cause of loss, a charge of 
manganese, once put into a still, when treated by this process, not only never needs to 
be replaced, but never needs even to be added to, while it will liberate an equivalent of 
chlorine every few hours for literally any length of time. The starting-point of any 
process for the regeneration of the oxide of manganese employed in the manufacture of 
chlorine, must, of course, be that residue which is known as “still-liquor,” being that 
which remains in the stills when oxide of manganese and hydrochloric acid have been 
digested together until all the chlorine which the oxide is capable of liberating from the 
acid has been liberated and given off. When working with a native oxide of manganese, 
the still-liquor contains, in addition to a quantity of protochloride of manganese equiva¬ 
lent to the quantity of oxide of manganese which has been dissolved, a considerable 
quantity of free acid, and more or less chlorides of iron and other bases, due to the 
native oxide of manganese being always more or less associated with other oxides. 
When working, however, with the artificial oxide of manganese produced as is about to 
be described, the still-liquor contains scarcely anything whatever but protochloride of 
manganese; and the new process consists simply in first*adding an equivalent of lime to 
this liquor, without removing the liquor from the still, and then blowing atmospheric 
air through the resulting mixture of protoxide of manganese and solution of chloride of 
calcium. The white protoxide is thereby rapidly converted into a very dark-coloured 
higher oxide, and when this product has been allowed to subside from the solution of 
chloride of calcium in which it was formed, and the greater part of that solution has 
then been drawn off from it, it is ready to be treated with hydrochloric acid, from which 
it then liberates chlorine, with reproduction of exactly as much protochloride of manga¬ 
nese as was commenced with. From this point the very simple series of operations 
described is repeated just as before, and so on, over and over again, for any required 
number of times. The manganese is thus constantly undergoing, always in one and 
the same vessel, a round of regularly recurring changes of state of combination, by 
which it passes, first from the state of protochloride to that of protoxide, next from the 
state of protoxide to that of a higher oxide, capable of liberating chlorine from hydro¬ 
chloric acid, then back again to the state of protochloride, and so on continually. As 
regards the richness of the oxide produced by the process above described, sesquioxide is 
all that one would have expected to obtain by means of it, but it actually yields a richer 
product than sesquioxide. Sesquioxide of manganese is, practically—at least from a 
chlorine manufacturer’s point of view—a mixture or compound of about 55*5 per cent. 
* Read before the British Association at Dundee. 
