RELATIONS TO OTHER SCIENCES 679 



lasting obligations to physics. It makes use of the physical pro- 

 perties of matter for purposes of identification and separation. It 

 employs her instruments, such as the spectroscope, the polariscope, 

 the microscope, the photometer, and a multitude of others, in ana- 

 lytical operations. It utilizes the various manifestations of energy 

 in accordance with the physical laws which govern them, adopting 

 the methods of transformation, conveyance, and application which 

 the physicist has shown to be most efficient, convenient, and safe, 

 though adapting them to the particular circumstances which obtain. 

 It relies upon the physicist for the verification of its standards of 

 mensuration, and, as previously stated, it employs physical, to- 

 gether with chemical, processes in its treatment of material in 

 manufacture. A modern instance of this relation of technical 

 chemistry to physics is found in the electro-chemical industry. 

 Starting with the remarkable experiments of Sir Humphry Davy 

 in 1807, which resulted in the isolation of sodium and potassium, 

 the commercial utilization awaited the discovery of an adequately 

 cheap source of available electrical energy, which was realized on 

 the invention of the dynamo in 1867. When its practicability 

 was demonstrated, and especially after it had been shown that a 

 head of water could be employed as the primary source of this 

 energy, the electro-chemical industry began and achieved such 

 proportions that in the year 1900, in the United States alone, phos- 

 phorous, sodium, and other metals, not including aluminium, were 

 isolated, and caustic soda, bleaching powder, and other bleach- 

 ing agents, bromine and potassium bromide, potassium chlorate, 

 litharge, graphite, calcium carbide, carborundum, and carbon 

 disulphide, amounting in value to $2,045,535, were manufactured 

 by electro-chemical methods. Many other products have been ob- 

 tained by this means in the laboratory and have been expected in 

 the industry; but while the industry is a growing one it is not grow- 

 ing as rapidly in the variety of its products as some have been led 

 to anticipate. Much depends upon the extent to which low-cost 

 sources of energy are to be commanded, and on this point the fol- 

 lowing from J. W. Richards 's presidential address to the American 

 Electrochemical Society in 1903 is pertinent. He says: 



" Niagara Falls is the most accessible of our great water-powers, 

 and has therefore drawn into its fold the majority of our electro- 

 chemical industries. But another source of surplus power is dis- 

 tributed over a large part of our country in a condition at present 

 as undeveloped as was Niagara's power when Columbus touched 

 our shores. I refer to the surplus power from blast-furnaces, ob- 

 tainable by using gas-engines. Every blast-furnace burns its gases 

 to heat its blast and to raise steam for its power. The two thirds 

 of its gases used for the latter purpose generate just about the power 



