( 801 } 
even to occur for some aqueous solutions. It is, however, reqnired 
3 % : dik Ov d 
for a negative value of a that the sum of 5 becomes negative 
ap Mt 
for all the substances of the system, and this is of course, still less 
probable. Hence it may be safely assumed that a negative value of 
dik 
a will not occur in the case considered up to now. When the 
solvent takes part in the reaction (in the above-mentioned sense, that 
only those collisions are favourable in which also the solvent parti- 
cipates, so without change of its quantity during the reaction), also 
the thermodynamic potential of the solvent will have to be inserted 
under the © sign in our equation. So in equation (12) one more term 
(=) will occur on the right side, which refers to the solvent. This 
will, however, not easily affect our conclnsions about the sign of 
dlk 
dp 
plays a part. If eg. we think the H-ions of an added acid active 
as a catalyser, the change of the thermodynamic potential of these 
H-ions with change of the pressure will not be represented by a term 
It is, however, a different matter, when also a catalytic agent 
dv 
as ( , because there neither the possible modification of the degree of 
n 
dissociation by the increase of pressure, nor the appearance of hydrate- 
ions has been taken into account. So the fact that Roramunp found 
a negative value of = in the conversion of cane-sugar under influence 
ap 
of HCl, need not be in contradiction with equation (2), and equation 
(12) derived from it. In the few other cases known to us, where 
the influence of the pressure on the velocity of a reaction has been 
examined, a positive value is found, but this experimental material 
is certainly still too scanty to justify a conclusion concerning equation 
(2). A more complete knowledge of the facts, preferably concerning 
reactions where the last mentioned complications do not occur, might 
possibly enable us to decide about the suppositions which lead to 
equation (2). 
Other conclusions from equation (2), which may be tested by 
experiment, will be found for concentrated solutions. For it is clear, that 
then the values u’, ete. must no longer be considered independent of 
the concentrations, in other words that the #, and /, can no longer be 
constant, so that deviations from the law of mass-action present 
themselves, as has actually been found in the inversion of cane- 
sugar. We hope to return to this point later on. 
52* 
