195 
[ Dolbear. 
1891.] 
tionally stronger. Such a disruption of a molecule is called dis- 
sociation and is produced by high temperature. Dissociation, 
however brought about, results in giving to the atom so set free 
its undiluted field, the maximum strength it can have at that tem- 
perature, hence the freedom and ease with which it can enter into 
new combinations. This is the nascent state. Dissociation results 
in cases where the reaction is simply an exchange of atoms in one 
or both molecules acting, for instance, NaOH -|- HC1 = NaCl-f- 
H 2 0. 
Here the field of NaOH is rendered weaker in the presence 
of HC1 and the harmonic rates of Na and Cl are more concor- 
dant than those in the other combinations. Whenever the field of 
one molecule weakens or neutralizes the field of another the degree 
of cohesion existing in the latter case must be lessened, and hence 
chemical reactions may take place which might not otherwise. 
Now there are numerous cases of this sort well known. For in- 
stance, a much lower degree of heat is needed to dissociate oxygen 
from KC10 3 if MnO s be present. The latter takes no part in the 
reaction itself, but it provides the chemical field that permits 
other reaction to occur which would not otherwise. The sig- 
nificance of a “flux” for fusing “refractory” compounds is thus 
made apparent. It is a pertinent question to ask if one can 
tell how far from a given molecule or surface of molecules this 
field extends. I do not know, but I have lately read of some 
German researches into the different rates of chemical reaction 
in a beaker, those nearest the surface of the glass going on at a 
swifter rate than those more remote from it. This method of 
explaining such a result is to say that the glass molecules have a 
field of their own as do any other molecules that extends to an 
appreciable distance from the surface which must lessen the de- 
gree of cohesion among other molecules there and thereby facil- 
itate other changes. 
Allusion has already been made to other kinds of physical fields 
such as the magnetic and the electrical ; it remains to point out a 
physical property that belongs to all such fields, namely, it reacts 
upon other bodies in them in such a way as to compel these bodies 
to assume similar states to those which produced the field. For 
example, a sounding body sets up in the air a kind of radiant en- 
ergy that makes other bodies to vibrate at the same rate. If the 
natural rate of the second body is the same as that of the first, 
