Maech 19, 1897.] 



SCIENCE. 



485 



sion and asmotic pressure to the lead cell was 

 first made by Le Blanc. This theory is farther 

 developed in the article. The number of tetra- 

 valent lead ions at the positive plate of a 

 charged lead cell is very small. When a cur- 

 rent is taken from the cell, PbSoj is formed 

 when the point of saturation of bivalent lead 

 ions is reached. If the formation of such a 

 product involves time, a supersaturation of bi- 

 valent ions would rapidly follow. This is es- 

 pecially true if the current is large. Upon the 

 Nerust theory this would produce a rapid fall 

 in the electro-motive-force of the cell, until 

 equilibrium is produced, i. e., until the rate of 

 precipitation of the lead sulphate is equal to its 

 rate of formation. In the charging process 

 there would be a corresponding diminution in 

 the products of ionization, and the charging 

 electro-motive-force must rapidly rise above the 

 normal electro-motive-force of the cell. Ex- 

 periment confirms these deductions from the 

 Nernst theory, and shows that these initial 

 changes take place largely within the first two 

 minutes after closing, or after opening the cir- 

 cuit. Debarring this initial change in the cell, 

 which causes large losses in energy, the curve 

 of the electro-motive-force of the cell is shown 

 to agree through a wide range with changes in 

 electro-motive-force brought about by progres- 

 sive changes both in the solution tension of the 

 electrode and in the pressure of the ions. It is 

 shown that Planck's thermodynamic treatment 

 leads to the same deductions. 



On the Influence of Electrification upon Surface 

 Tension of Water : By E. L. Nichols and J. A. 

 Clark. In this paper an attempt was made to 

 determine by quantitative measurements the 

 change in the surface tension of liquids to 

 which the well-known effect of electrification 

 upon water jets, etc., is due. The method pur- 

 sued was that of the water dropper. A reser- 

 voir from which the water drops proceeded was 

 kept charged by the continuous action of a 

 Holtz machine driven by an electric motor. A 

 large battery of Leyden jars furnished the cir- 

 cuit with sufl[icient capacity to prevent rapid 

 fluctuations of potential. 



The electrification of the reservoir was meas- 

 ured by means of a form of an absolute electrom- 

 eter ; the temperature of the falling drops by 



means of a thermo-electric junction. The range 

 of potentials was from zero to 11,000 volts. 

 Beyond the latter value measurements became 

 impossible because drops were no longer 

 formed. The result of these measurements in- 

 dicates that the surface tension falls off at first 

 slowly, and then more and more rapidly as the 

 potential rises, until at 10,000 volts it has been 

 reduced to about one-half its value for the elec- 

 trified liquid. No difference could be detected 

 between the action of positive and negative 

 charges. 



On the Mechanical Conceptions of Electricity 

 and Magnetism : By "W. S. Franklin. This 

 paper develops detailed mechanical concep- 

 tions of various electro-magnetic phenomena, 

 based upon the fundamental conceptions of 

 Maxwell, with particular reference to the 

 quantitative relations which hold among the 

 various electro-magnetic quantities. Among 

 other things, a minute description is given of 

 the action which takes place in the region sur- 

 rounding a Hertz oscillator. 



On a Possible Development of the Idiostatic 

 Electrometer: By C. Barus. The idiostatic 

 electrometer has not hitherto been developed 

 to an extent comparable with the quadrant 

 electrometer ; yet it possesses the advantage 

 that it introduces no foreign potentials to co- 

 operate with those under investigation. The 

 writer describes certain results obtained in an 

 endeavor to perfect the idiostatic electrometer. 

 The moving system was supported by a double 

 bifilar suspension. The disc was made very 

 light and protected by a guard ring. The ex- 

 cursions of the disk were observed by Michel- 

 son's refractometer. Thus in one case ten 

 fringes passed for a single volt ; estimating 

 0.1 fringe the sensitiveness thus became 0.01 

 volt. 



Empirical Formulse for Viscosity as a Function 

 of Temperature: By A. Wilmer Duff. Sev- 

 eral formulse for the viscosity of liquids at dif- 

 ferent temperatures have been proposed. The 

 writer classifies and discusses these and con- 

 siders means of interpolation and extrapola- 

 tion. 



A synchronous Motor for Determining the Fre- 

 quency of an Alternating Current: By GEORaE 

 S. MOLER. This paper describes an exceed- 



