844 



Voltaic Electricity. Section 1: Galvanic Sources of Current. 



Xo. 60 72 J 



60 725 A. 1 : 8. 



60 725 B. 1:4. 



60727. 1:6. 



60 726. 1 : 6. 



60729. 1:4. 



60.725. Mirror Electrometer for High Potentials, as suggested by Heydweiler, Figs. A 

 and B (Ztschr. f. d. phys. u. chem. U. 6, p. 255; Ztschr. fur Instrumentenkunde 12, 

 p. 377; Elektrotechnische Ztschr. 1893, p. 29), with 2 bifilar suspensions, easily inter- 



' changeable, for measurements of 3000 to 27,000 volts and of 6000 to 50,000 volts. . 



The instrument is essentially a torsion balance and has the advantage that the potentials to 

 be measured are nearly proportional to the square root of the scale readings. The results are very 

 accurate. 



The electrometer has a good damping arrangement. 



Subjective and Objective Reading Devices for Electrometers Nos. 60719 to 60725: see Mirror 

 Galvanometers. 



60.726. Absolute Electrometer (Electrometer Balance with protecting ring condenser), as 

 suggested by Thomson-Kirchhoff , Figure, without balance 



The lower of two circular plane parallel condenser plates of gilt brass is fixed in an insulating 

 material, while the upper is suspended on a sensitive balance in the manner of a balance pan. 

 The balance suitable for the above is No. 51,542 on p. 234. 



Standard Cells. 



60.727. Standard Copper-Zinc Cell (Weinhold's), Figure (\V. I), p. 752 [694]) 



10. 0. 



60.728. Standard Cell (Kittler's), with chemically pure copper and zinc plates, in polished 

 oak case with handles 



Sulphuric acid of 1.075 specific gravity at 80 C. and a solution of copper-sulphate of 1.19 sp. 

 gravity is used for charging. E. M. F. 1.182 v. at 15.5 C. 



60.729. Standard Cell (Fleeming's), Figure (M. P. 9 th edn., Ill, Fig. 304; Kolbe-Skellon, 

 Introduction to Electricity, Part II, Fig. 113; Can. -Man. Fig. 726) 



60.730. Clark Standard Cell, self-filling type as suggested by Ostwald, Figure, with 

 pole terminals 



< 1.2211, 2212, 

 2213, S850. 



16. 0. d 



0.10. 

 2.10. (i 



1.1-2.0 

 0. 1. 



5793 . 



