which must not and cannot claim in the least to represent the real 
nature of things. It is also owing to this insight, that several voices 
have been raised of late in favour of the use of the thermodyna- 
mical potential. 
§ 3. Now I think that I have convincingly proved the incorrect- 
ness of the second thesis in the preceding paper, and as 1 gladly 
and with full conviction range myself with the “tastbaarheids- 
menschen,” (those who want to form a clear idea of the physical 
meaning of each term used), whose opinion Mr. van Laar severely 
condemns, his reasoning would lead me to take side against the 
thermodynamic potential party when T could subseribe to his first 
and his last thesis more than to his second. This however, is by no 
means the case. 
The last philosophical-historical thesis I can, naturally, not discuss 
here and | confine myself therefore to that concerning the physical 
meaning of the thermodynamical potential. [t seems to me that we 
can form an idea of this quantity which need not be inferior 
to that of any other statistical quantity. That Mr. Van Laar has 
overlooked this fact seems chiefly owing to two circumstances of 
which it may appear that one can have hardly any influence, for it is 
simply a question of nomenclature. Following a common way of 
speaking, which does not seem to me the less reprehensible for the 
fact that it is of frequent occurrence, Mr. Van Laar does not give 
the name of “thermodynamical potential” to the quantity introduced 
by GaBBs into science by that name, but to one of the other functions 
introduced by Gipps, the &-funetion. There are more reasons than 
only a feeling of deference, which make this undesirable. The real 
(Gras) potential zs really a potential, i. e. it is constant in a space 
where equilibrium prevails, and its not being constant means, that 
there is no equilibrium. At least when there act no capillary or 
external forces; and in this case the resemblance of the thermody- 
namic potential with the potentials of other energies stands out per- 
haps the more clearly. For in this case we need only add to the 
(Gipps’) thermodynamic potential the other potentials, which exist in 
that space in order to get a quantity, the total potential, which now 
also is constant throughout the space in case of equilibrium. The 
S-funetion has neither the one property, nor the other, except when 
we have to deal with a simple substance without capillary layers, 
in which case it becomes identical with the thermodynamic potential. 
If now also in $$6 and 7 Mr. Van Laar had directed his atten- 
tion instead of to the $-function, to the real potential, as he has done 
in $ 4, where he carries out his calculations by means of it, it would 
probably not have escaped his notice that he wrongly represents the 
