Conducting -power of the Chlorides of the Alkalies, fyc. 421 



The dependence of the conducting -power of the chlorides on the 

 temperature shows, according to the above, great simplicity in 

 many respects. The universally small amount of the coefficient 

 $ proves that, with all solutions, the conducting -power increases 

 in nearly equal proportion with the temperature ; the positive sign 

 of /3, that each of the slight deviations consists of an acceleration. 



With so strongly pronounced a dependence as we have here 

 (with which 30° rise of temperature about doubles the conduct- 

 ing-power), this nearly equal proportional augmentation could 

 not a priori be expected. It has, however, been observed also in 

 sulphate-of-zinc and sulphuric-acid solutions*, and appears to 

 be a universal property of liquid conductors. Viscous substances 

 only, such as concentrated solutions of chloride of calcium, 

 chloride of magnesium, and sulphuric acid, exhibit greater in- 

 equality. 



A further, very remarkable fact is the near approximation to 

 equality of the temperature-coefficients for the different chlorides in 

 dilute solution. Those at 18'", for example, for all 5-per-cent. 

 solutions, lie between ^ (for LiCly and y' 2 (for NH 4 C1); the 

 graphic representation permits the conjecture that with further 

 dilution they would come still nearer together; nay, it is pro- 

 bable that they tend to the same limit (about ^ 7 ). And cer- 

 tainly this limit cannot signify the temperature-coefficient of 

 pure water, since the conducting-power of this is generally a 

 vanishing quantity in comparison with the numbers in the above 

 Table. The temperature-coefficient of sulphate-of-zinc solution, 

 too, observed by Beetz, appears as the dilution is increased to 

 approach towards about the same limit. 



With increasing amount of salt contained, all the temperature- 

 coefficients at first diminish. Afterwards the substances divide 

 themselves into two groups: KG, NH 4 CI, and BaCl 2 show a 

 diminution of the coefficients up to the greatest concentration, the 

 coefficient sinking in the case of NH 4 C1 to the lowest value, ? . 1 r . 

 NaCl, CaCL,, and MgCl 2; on the contrary, have a minimum be- 

 tween 10 and 20 per cent. ; and thence onward the coefficient 

 rises, that of MgCl 2 even to ^. This group -difference appears 

 to be connected with a maximum of conducting-power with the 

 salt-content, exhibited by the latter substances, but not by the 

 former. ^Compare what is stated below.) 



Nitric acid connects itself with the latter group. In the sign 

 of /3 changing from — to + it agrees with sulphuric acid; yet 

 the inequality of the augmentation between 0" and 40° is gene- 

 rally slight. The absolute amount of the influence of tempera- 

 ture is less than with the chlorides, and not very different from 

 that observed with hydrochloric and sulphuric acids. 



* Beetz, Pogg. Ann. vol. cxvii. p. 21 ; Grotrian, ibid. vol. cli. p. 3D4, 



