383 



Evidently then, the (emperature coeflicieiily of Kohlbaisch can 

 not be relied on to obtain accurate values at 0° C. 



Wood') has given the ibllowing values for n^ at 0°: for KCl = 

 77.8, for NaCl = 65.0, for dichloracetic acid = 227.0, for trichlor- 

 acetic acid = 224.7. Thus from Ihe values obtained by me it is 

 seen tliat his values for KCl and NaCl are a little too low, whilst 

 his values for Ihe acids are very much too low, since the most 

 probal)le value of H° is 223.9. 



Johnston's') rough estimation of Ihe value of H° at 0° =: 240 is 

 also far from being correct. 



NoYES and Stewart'') ha\e deduced \aluos for H° in an indirect 

 way which can hardly be relied on. Whilst from data for HCl they 

 obtained the velocity for H° at 0° ^ 224, they, at the same lime 

 obtained, by considering H.^SO., in the same way the value 235 at 0°. 



NoYEs and Coolidge ■*; give 81.4 as the value of n^ for KCl at 

 0°; but it is a little too low. 



Jones and West'^) have given ft^ at 0° for NII,C1 ==: 74.84; 

 evidently it is too low. 



Jones and Caldweu/) give the value for ammonium nitrate 

 = 78.0, which is a value a little too low. 



Kahlenberg') obtains for strontium nitrate the value GG.i. Evidently 

 it is too low, since the correct value would be about 31.7 -|- 41.3 = 

 73 (loc. cil). 



HiLi, and Sikcah') take a very high value for H° at 0°. They 

 wrile: Kor n^ in the case of hydrogen fluoride, we have taken 

 the number 3(54 at 18° and 325 at 0°. The first number is derived 

 from the ionic conductivities at 18° which are 318 for the hydrogen 

 ion and 46.6 for the fluorine ion. The .second number is derived 

 from the following data: 



"Ostwald gives 325 as the ionic conductivity of the hydrogen 

 ion at 25°; at 18° the value is 318 (Kohlraisch and v. Steinwehr, 

 Sitz.-ber. Berlin. 4kad. 1902), being a fall of one unit per degree. 

 Hence at 0" the value would be approximately 300. Correcting 

 the ionic conductivity of fluorine for temperature, the temperature 

 coeftieient being 0.0238, we get the value at 0° = 26.6. The sum 



1) Loc. cit. 



-) J. Amer. Gliem. Soc. 31, 1015 (l'.)Oy). 



^) J. Amei-. Gliem. Soc. 32, (1910), 114.l)-1141. 



') Carnegie Institution Publications 63, 47 (1907). 



6) Amer. Chem. Jour. 34, 557 (1905). 



6) Amer. Chem. Jour. 25, 349 (1901). 



') Jour. Phys. Chem. 5, 339 (1901). 



8) Proc. Koy. Soc. Vol. 83 A, p. 130. 



