TABLE 293. 26 1 



ABSOLUTE MEASUREMENTS OF CURRENTS AND OF THE ELECTRO- 

 MOTIVE FORCE OF STANDARD CELLS. 



* The values given in these columns are not strictly absolute volts since they were in most cases determined in terms 

 of an absolute ampere and an international ohm. Hence they may be called "semi-absolute." No absolute determina- 

 tions of the ohm have been made in recent times, but some are in progress. 



t Other values usually given as Kahle's results and officially used by the Reichsanstalt are voltameter determinations. 

 To include them here would necessitate including many others similarly made. The value 1.1183 includes 5 filter paper 

 determinations out of 26 observations. 



t These values have been corrected for the difference between the French ohm at this time and that in use elsewhere. 

 (C. R. vol. 153, P- 7i8.) 



Measurements prior to Van Dijk (1906) and the subsequent filter paper voltameter determinations are now only of 

 historical interest, but the large amount of work done in recent years makes these early determinations of especial inter- 

 est. The errors due to the use of filter paper and other impurities (acid, alkali, colloidal matter, etc.) in the voltameter 

 electrolyte make it impossible to apply corrections. The values for the cell are not readily comparable owing to varia- 

 tions in the voltage of the cell itself and the unit of resistance. See Dora, Wiss. Abhl. der Phys. Tech. Reich., vol. II, p. 

 257. Since 1911 the voltage adopted for the Weston Normal Cell at 20 C. is 1.0183 international volts in all the leading 

 countries. The international volt is to be distinguished from the absolute volt since it is based on the definition of the 

 mercury ohm and the silver voltameter, taking the electrochemical equivalent of silver to be 1.11800 mg per coulomb. 

 The difference between the international volt and the absolute volt is negligible for practical purposes. The tempera- 

 ture coefficient of the Weston Normal Cell (saturated type) is given in Table 294. The new value of the Weston cell was 

 adopted in the United States on January i, 1911. 



SMITHSONIAN TABLES. 



