TRANSACTIONS OF SECTION B. 745 
in the first instance chlorine and an amalgam of sodium, and subsequently con- 
verting the latter into caustic soda by contact with water, which certainly has 
the advantage of producinga very pure solution of caustic soda. Mr. Hamilton 
Castner has carried out this idea most successfully by a very beautiful decomposing 
cell, which is divided into various compartments, and so arranged that by slightly 
rocking the cell the mercury charged with sodium in one compartment passes into 
another, where it gives up the sodium to water, and then returns to the first com- 
partment, to be recharged with sodium. His process has been at work on a 
small scale for some time at Oldbury, near Birmingham, and works for carrying 
it out on a large scale are now being erected on the banks of the Mersey, and also 
in Germany and America. 
Entirely different from the foregoing, but still belonging to our subject, are 
methods which propose to electrolyse the chlorides of heavy metals (zinc, lead, 
copper, &c.) obtained in metallurgical operations or specially prepared for the pur- 
pose, among which the processes of Dr. Carl Hoepfner deserve special. attention. 
They eliminate from the electrolyte immediately both the products of electrolysis, 
chlorine on one side and zine and copper on the other, and thus avoid all secondary 
reactions, which have been the great difficulty in the electrolysis of alkaline 
chlorides. 
All these processes have, however, still to stand the test of time before a final 
opinion can be arrived at as to the effect they will nave upon the manufacture of 
chlorine, the history of which we have been following, and this must be my excuse 
for not going into further details. I have endeavoured to give you a briet history 
of the past of the manufacture of chlorine, but I will to-day not attempt to deal 
with its future. Yet I cannot leave my subject without stating the remarkable 
fact that every one of these processes which I have described to you is still at work 
to this day, even those of Scheele and Berthollet, all finding a sphere of usefulness 
under the widely varying conditions under which the manufacture of chlorine is 
carried on in different parts of the world. 
Let me express a hope that a hundred years hence the same will be said of the 
processes now emerging and the processes still to spring out of the inventor’s mind. 
Rapid and varied as has been the development of this manufacture, I cannot sup- 
pose that its progress is near its end, and that Nature has revealed to us all her 
secrets as to how to procure chlorine with the least expenditure of trouble and 
energy. I do not believe that industrial chemistry will in future be diverted from 
this Section and have to wander to Section A under the egis of applied electricity. 
I do not believe that the easiest way of effecting chemical changes will ultimately 
be found in transforming heat and chemical affinity into electricity, tearing up 
chemical compounds by this powerful medium, and then to recombine their con- 
stituents in such form as we may‘require them. I am sure there is plenty of scope 
for the manufacturing chemist to solve the problems before him by purely chemi- 
_ cal means, of some of which we may as little dream to-day as a few years ago it 
could have been imagined that nickel would be extracted from its ores by means 
of carbon monoxide. 
At a meeting of this Association which brings before us an entirely new form 
of energy, the Réntgen rays, which have enabled us to see through doors and walls 
and to look inside the human body ; which brings before us a new form of matter, 
represented by Argon and Helium, which, as their discoverers, Lord Rayleich and 
Professor Ramsay, have now abundantly proved, are certainly elementary bodies, 
inasmuch as they cannot be split up further, but are not chemical elements, as they 
possess no chemical affinity and do not enter into combinations—at a meeting at 
which such astounding and unexpected secrets of nature are revealed to us, who 
would call in dcubt that, notwithstanding the immense progress pure and applied 
_ sciences have made during this century, new and greater and farther-reaching 
_ discoveries are still in store for ages to come ? 
1896. 3c 
