ON ELECTROLYSIS AND ELECTRO-CHEMISTRY. 221 
deduced from the dynamical theory of heat as applicable to the osmotic 
phenomena of solutions, where T is the absolute temperature, P is the 
partial pressure of the combined molecules, p,p. the partial pressures of 
the dissociated ions, A the dynamical equivalent of heat, W the heat of 
formation of the molecules from the ions, he obtains the equation 
oe @ lopig hy lek W 
rr aL ae 
Whence, substituting values of A and R in meter-gramme units 
i (4244./0°981 and 845°05 respectively), we get 
W=1-945 x 2:35 T? Togo k + 1-945 T, 
: 
Ny 
_ where W is expressed in gramme-calories ; & can be determined from the 
conductivity measurements, and hence d log k/dt approximately deter- 
_ mined which is denoted by 8, and hence the value of W determined for 
_ the mean temperatures 35° C. (between 18° and 52°) and21°°5 (between 
18° and 25°). The results are as follows :— 
PS Ae eM 
ie At 35° At 21°5° 
Name | W;;—W. i 
Wss Wars iat 
CH,COOH +220 +600 —380 
C,H,COOH : : ; +50 +390 —340 
'.|C,H,COOH. : 4 — 320 +150 —470 
Mepe.H(COOH),. . .| +1040 +1690 —650 
| CHCI,COOH hate: — 2240 —2390 +150 
ate —1820 —1530 —290 
HOPOH, . — 3630 —3180 —450 
HF (at 33°) —2960 a aia 
B.—Strongly dissociated Bodies at 35° (from Observations in decinormal 
Solutions). 
Name W335 Name Wss 
KBr +180 NaCH,COO . +210 
KI —300 NaC.H,COO . +690 
KCl +250 Na0Q,H,COO. +1140 
KNO, +470 NaHC,H,(COO), . +1110 
NaCl +140 NaCHCl,CoO —190 
LiCl +210 NaOPOH, . +410 
BaCl, +300 NaH,P0, +220 
} imgci, —40 HCl. — 460 
| 4caso, ’ —940 HNO, —740 
| NaF +530 HBr. f+ —990 
NaOH . — 670 
The table shows that heat is sometimes developed and sometimes 
absorbed by the separation of a molecule into ions. 
The values thus obtained are next applied to calculate the heat of 
neutralisation of the salts investigated. Taking Ostwald’s suggestion 
of the process taking place in neutralisation and setting d,, da, d3 for 
