520 Scientific Intelligence. 



ance of the upper harmonics in resonant circuits through 

 which tveak currents flow, and their entire absence from 

 resonant circuits traversed by strong currents. 



I expect to follow up this subject more closely and I do not 

 know of any method by which it could be studied with greater 

 ease and accuracy than by the method of resonant rise of poten- 

 tial. The circumstance that low frequency resonance offers so 

 delicate a method for the study of electromagnetic phenomena 

 such as 1 just described seems to me to make the subject of slow 

 frequency resonance even more important than the fact that by 

 it rise of potential and weeding out of harmonics can be 

 produced. 



Before closing this paper I must thank my pupil Mr. M. C. 

 Canfield, postgraduate student in Electrical Engineering, for 

 the very efficient way in which he has aided me in these exper- 

 iments. 



Electrical Engineering Laboratory, School of Mines, 

 Columbia College, New York, May 8th, 1893. 



SCIENTIFIC INTELLIGENCE. 



I. Chemistry and Physics. 



1. On the Loss of Energy due to Chemical Union. — In order 

 to measure the loss of energy due to a given chemical action, 

 Gore has proposed to determine the electromotive force between 

 a plate of platinum and a plate of some other metal (usually 

 aluminum, tin, cadmium, zinc or magnesium) immersed first in 

 the two given solutions separately and then in the two mixed to- 

 gether. Thus for example he takes a known quantity of an acid 

 dissolved in a known mass of water and measures the electro- 

 motive force A developed by a small platinum-aluminum couple 

 immersed in the solution. He then takes a quantity of a base 

 chemically equivalent to this, dissolved in the same mass of water, 

 and measures the electromotive force B developed by the same 

 couple. Finally he determines in the same way the electromotive 

 lorce C in a solution containing the equivalent quantity of the 

 salt resulting from the combination of the acid and base already 

 used. Multiplying then the equivalent mass of the acid into its 

 electromotive force A, and that of the base into its electromotive 

 force B, adding these together and dividing the sum of the prod- 

 ucts by the sums of the equivalents, he obtains a value D. Sub- 

 tracting C from D and multiplying by 100 / D, the product 

 represents the loss or gain of electromotive force in percentages ; 

 and this the author regards as expressing the relative loss or gain 

 of molecular energy which has taken place upon the union of the 

 acid and the base. In the paper the results of numerous experi- 



