THE CONQUEST OF NATURE 



sweltered all day long in an almost unbearable atmos- 

 phere stripped to the waist, dripping with perspiration, 

 sometimes overcome with heat. Their task was one 

 of the most trying to which a man could be subjected. 



But to-day, in such establishments as the soda manu- 

 factories at Niagara Falls, all this is changed. A salt 

 solution circulates continuously in retorts where it can 

 be acted upon by electricity supplied from dynamos 

 operated by the waters of the Niagara River. The 

 workmen, comfortably dressed and moving about in 

 a normal temperature, have really nothing to do but 

 refill the retorts now and then and remove the finished 

 product. "It almost seems," Professor Chandler 

 added with a smile, "as if workmen ought to be glad 

 to pay for the privilege of participating in so pleasant 

 an occupation. At all events it is, in all seriousness, 

 a pleasure for the visitor who knows nothing of old 

 practices to witness this triumph of a modern scientific 

 method." 



Even more interesting, said Professor Chandler, are 

 the processes employed in the modern method of pro- 

 ducing the metal aluminum by the electrolytic process. 

 The process is based on the discovery made by Mr. 

 Charles M. Hall while he was a student working in 

 a college laboratory, that the mineral cryolite will 

 absorb alumina to the extent of twenty-five per cent, 

 of its bulk, as a sponge absorbs water. The solution 

 of this compound is then acted on by electricity, and 

 the aluminum is deposited as pure metal. A curiously 

 interesting practical detail of the process is based on the 

 fact that pulverized coke remains perfectly dry and 



[300] 



