Conducting-power of the Chlorides of the Alkalies, §*c. 419 

 mercury unit to absolute measure f, served for this reduction. 



The resistance of a column of liquid of 1 square millim. base 



and 1 millim. length, is found to be, in absolute measure, 



9717000 millim. „,. . millim. 2 . milligr. . L . 



= : . Ibis, in h — — , is at the same 



k sec sec/ 



time the work of the unit current which passes this column in a 



second. 



Scarcely any property of bodies depends to so great a degree 

 upon the temperature as the conductivity of electrolytes, which 

 at middle temperatures is influenced as much as ten times as 

 powerfully by heat as the pressure of a gas. On this account 

 observations of the resistance without statement of the tempera- 

 tures of liquids possess but little value. 



But even apart from this, the influence of temperature is here 

 of singular importance, precisely on account of its unusual mag- 

 nitude ; for it follows that the electro-chemical work of the cur- 

 rent stands in intimate relation with the thermal condition of the 

 liquid, the tracing-out of which relation may supply an invalu- 

 able explanation on the nature of electrolysis. We have com- 

 prehended the observations of each solution in the formula 



A, = * (1+ «* + #*)> 

 in which k t signifies the conductivity at temperature t. 



Besides these constants k , a, and (3, the following Table con- 

 tains the conducting-power at 18° multiplied by 10 8 , and, finally, 



under (7-77) > the increment for 1° in the vicinity of 18°, ex- 

 pressed in fractions of the conducting-power at 18°. 



The percentages denote parts by weight of anhydrous salt, or 

 of nitric-acid hydrate, in parts by weight of the solution. The 

 specific gravities are for 1 8°. 



The solutions marked with an asterisk (*) have not been ana- 

 lyzed ; but their content was taken, according to the specific 

 gravity, from B. Hoffmann's Tabellen fur Chemiker. The con- 

 ducting-powers &c. set down for the bracketed percentages were 

 interpolated from a graphic representation of the results, and are 

 here and there uncertain to a few units in the last place. The 

 most concentrated solution of NH 4 C1 precipitated some crystals 

 at 0°, -when a leap in the conducting-power was not observed. 

 Two solutions of MgCl 2 were examined only at 18° and 30° ; and 

 two of SiCl 2 , at 18° only. The strongest nitric contained a little 

 nitrous acid. 



t Nachrichten, 1870, p. 513. It is not unimportant to remark that the 

 present comparison of the two standards gave, to within 5 o"o o> tne same 

 ratio as that made four years previously. 



2G2 



