738 REPORT—1896. 
being a chemist, he did not add the equivalent quantity of lime to his liquor to 
precipitate the manganese, but used an excess. However, Mr. Weldon, if he was 
not a chemist at that time, was a man of genius and of great perseverance. He 
soon made himself a chemist, and having once got a satisfactory result, he studied 
every small detail of the reaction with the utmost tenacity until he had thoroughly 
established how this satisfactory result could be obtained on the largest scale with 
the greatest regularity and certainty. 
He even went further, and added considerably to our theoretical knowledge of 
the character of manganese peroxide and similar peroxides by putting forward the 
view that these compounds possess the character of weak acids. He explained in 
this way the necessity for the presence of an excess of lime or other base if the 
oxidaticn of the precipitated protoxide of manganese by means of atmospheric air 
was to proceed at a sufficiently rapid rate. He pointed out that the product had 
to be considered as a manganite of calcium, a view which has since been 
thoroughly proved by the investigations of Geergen and others; and it is only fair 
to state that Weldon’s process is not only a process for recovering the peroxide of 
manganese originally used, but that he introduced a new substance, viz., manga- 
nite of calcium, to be continuously used over and over again in the manufacture of 
chlorine. 
Mr. Weldon had the good fortune that his ideas were taken up with fervency 
by Colonel Gamble of St, Helens, aud that Colonel Gamble’s manager, Mr. F. 
Bramwell, placed all his experience as a consummate technical chemist and 
engineer at Mr. Weldon’s disposal, and assisted him in carrying his ideas into 
practice. The result was that a process which many able men had tried in vain 
to realise for thirty years became in the hands of Mr. Weldon and his coadjutors 
within a few years one of the greatest successes achieved in manufacturing 
chemistry. 
The Weldon process commences by treating the residual liquor with ground 
chalk or limestone, thus neutralising the free acid and precipitating any sulphuric 
acid and oxide of iron present. The clarified liquor is run into a tall cylindrical 
vessel, and milk of lime is added in sufficient quantity to precipitate all the 
manganese in the form of protoxide. An additional quantity of milk of lime, from 
one-fifth to one-third of the quantity previously used, is then introduced, and air 
passed through the vessel by means of an air-compressor. After a few hours all 
the manganese is converted into peroxide ; the contents of the vessel are then run 
off; the mud, now everywhere known as ‘ Weldon mud,’ is settled, and the clear 
liquor run to waste. The mud is then pumped into large closed stone stills, where 
it meets with muriatic acid, chlorine is given off, and the residual liquor treated 
as before, 
You note that this process works without any manipulation, merely by the 
circulation of liquids and thick magmas which are moved by pumping machinery. 
As compared to older processes it also has the great advantage that it requires 
very little time for completing the cycle of operations, so that large quantities of 
chlorine can be produced by a very simple and inexpensive plant. These advan- 
tages secured for this process the quite unprecedented success that within a few 
years it was adopted, with a few isolated exceptions, by every large manufacturer 
of chlorine in the world; yet it possessed a distinct drawback, viz., that it pro- 
duced considerably less chlorine from a given quantity of muriatic acid than either 
native manganese of good quality or Mr. Dunlop’s recovered manganese. At that 
time, however, muriatic acid was produced as a by-product of the Le Blane pro- 
cess so largely in excess of what could be utilised that it was generally looked 
upon as a waste product of no value. Mr. Weldon himself was one of the very 
few who foresaw that this state of things could not always continue. The am- 
monia soda process was casting its shadow before it. Patented in 1838 by Messrs, 
Dyar and Hemming it was only after the lapse of thirty years (during which a 
number of manufacturing chemists of the highest standing had in vain endeavoured 
to carry it into practice) that this process was raised to the rank of a manufactur- 
ing process through the indomitable perseverance of Mr. Ernest Solvay, of Brussels, 
and his clear perception of its practical and theoretical intricacies. A few years 
