42 
PROF. 0. W. RICHARDSOX OX THE EMISSIOX OF ELECTROXS 
2K + Cl 2 —> 2KC1 + 208 -1 X 10 3 gm. cals. 
2Na + Cl 2 —^ 2NaCl + 197 X 10 3 gm. cals. 
2C + 0 2 + 2C1 2 —> 2C0CL + 88 - 2 X 10 3 gm. cals. 
2C + 0 2 -—> 2C0 4- 52 -2 X 10 3 gm. cals. 
The data are for solid K, Na, KC1 and Nad, for carbon in the form of diamond, and 
for gaseous d 2 , 0 2 , CO and C0C1 2 , in each case per gramme molecule, with the equations 
as written. It is difficult to conceive of any way in which the average energy of the 
electrons could exceed the equivalent of the heat of formation of two molecules of KC1 
from two molecules of K and one of Cl 2 ; in fact, it is practically certain to be much 
less than this. In general, if H is the heat available in gm. cals, per gramme molecule 
we shall have as a limit for T 
where k is Boltzmann’s constant 1 -346 X 10 -16 , J is the mechanical equivalent of 
heat 4 T84 X 10 7 , and N is the number of molecules per gramme molecule 6 -2 X 10 23 . 
If we put H = 208 -I X 10 3 this gives as a limit for T the value 69 - 7 X 10 3 . This is 
about 14 times the value deduced from the experiments. However, something has 
to be subtracted from the value of H for the unknown heat of formation of the liquid 
alloy from the solid constituents, and the assumption that the whole heat of the reaction 
is passed on to one electron is only worthy of consideration for the purpose of fixing a 
limit for T. It is much more likely that, the heat available is evenly divided among the 
different atoms taking part in the reaction. The number of these is doubtful owing to 
the somewhat uncertain degree of association of the reacting atom with its neighbours 
in the alloy. It is also possible that the actual reaction in which an electron is expelled 
is not correctly expressed by the equation of the end products written above, but is 
some intermediate reaction, such as 
K + Cl 2 —> KOI + Cl 
or 
NaK 2 + Cl 2 —> NaK + KC1 + Cl, 
or the like. In such a case the value of the heat available may be quite different from that 
given by the end products. It is impossible to make any precise statements where 
the data are so indefinite, but I feel that when all these factors are taken into account 
the value of T given by the experiments on chlorine is a reasonable one. 
This position is strongly supported when the value given by C0C1 2 is compared with 
that given by Cl 2 . It is most likely that the mechanism of the reaction is much the 
same in both cases, any difference arising mainly from the fact, that the Cl 2 is now 
loaded up with the CO group. This would have two effects. It would reduce the 
total amount of energy available by the difference of the heats of formation of CO and 
COCL>, i.e., by 18 X 10 3 gm. cals, for each gramme molecnle of COCL, and it would 
