236 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1914. 
were started at Niagara Falls. That ingenious mercury cell of 
Hamilton Y. Castner—a pupil of Prof. Chandler and one of the 
illustrious sons of the Columbia School of ‘Mines—was first used, 
and his process still furnishes a large part of all the electrolytic 
caustic soda and chlorine manufactured here and abroad. 
At present about 30,000 electrical horsepower are employed unin- 
terruptedly for the different processes used in the United States, 
and our home production has increased to the pomt where, instead 
of importing chloride of lime, we shall soon be compelled to export 
our surplus production. 
It looks now as if, for the moment at least, any sudden considerable 
increase in the production of chloride of lime would lead to over- 
production until new channels of consumption of chloride of lime or 
other chlorine products can be found. 
However, new uses for chlorine are being found every day. The 
very fact that commercial hydrochloric acid of exceptional purity is 
now being manufactured in Niagara Falls by starting from chlorine 
indicates clearly that conditions are being reversed; no longer than a 
few years ago, when chlorine was manufactured exclusively by means 
of hydrochloric acid, this would have sounded like a paradox. 
The consumption of chlorine for the preparation of organic chlori- 
nation products utilized in the dye-stuff industry is also increasing 
continually, and its use for the manufacture of tetrachloride of carbon 
and so-called acetylen chlorination products, has reached quite some 
importance. 
There is probably a much overlooked but wider opening for chlo- 
rinated solvents in the fact that ethylen gas can be prepared now at 
considerably lower cost than acetylen, and that ethylen chloride, or 
the old known ‘‘ Dutch Liquid,” is an unusually good solvent. It has, 
furthermore, the great advantage that its specific gravity is not too 
high, and its boiling point, too, is about the right temperature. It 
ought to be possible to make it at such a low price that it would find 
endless applications where the use of other chlorination solvents has 
thus far been impossible. 
The chlorination of ores for certain metallurgical processes may 
eventually open a still larger field of consumption for chlorine. 
In the meantime liquefied chlorine gas, obtained by great compres- 
sion, or by intense refrigeration, has become an important article of 
commerce, which can be transported in strong steel cylinders. Its 
main utilization resides in the manufacture of tin chloride by the 
Goldschmidt process for reclaiming tin scrap. It is finding also in- 
creased applications as a bleaching agent and for the purification of 
drinking water, as well as for the manufacture of various chlorination 
products. 
