3 JOURNAL OF THE 
to exert much influence, unless it influences the character of 
the motion. The atomic weight also has little influence in 
determining the number of atoms needed to satisfy the condi- 
tions of equilibrium except that there seems to be a general 
rule that with increase in the atomic weight in any one group 
more stable equilibrium is brought about with the smaller 
number of atoms and in a choice between several the lesser 
valence is preferred. (Compare nitrogen and bismuth; sul- 
phur and tellurium.) 
There would then appear to be seven, possibly eight,differ- 
ent kinds of motion among the atoms. Different velocities of 
vibration are not meant, but different phases of motion. For 
instance, all may have elliptical orbits with different: focal 
distances; or circular, with different radii, etc. In any group 
of elements the motion of the atoms would have one common 
characteristic but there would be differences in velocity. In 
the first and seventh group, showing, for the most part, a 
tendency towards the same equilibrium, or having the same 
valence, the motion must be closely analogous. So too for 
the second and sixth groups, the third and fifth. There may 
then be a necessity for four distinct phases only, unless we 
suppose a fifth for the eighth group. If the motion of an 
atom can be changed from one character to another its val- 
ence is changed and in such general properties as are depen- 
dent upon motion and not upon atomic weight it is equivalent 
to changing its group, Electricity, light, heat, and chemical 
action can cause this change of motion. Insofar the prop- 
erties of the element are subject to change and within our 
control. But the other factor, atomic weight, with the prop- 
erties of the element determined by it, is not subject to 
change nor within our control, so far as our knowledge 
goes. 
While it is freely granted that there is so much of the spec- 
ulative in what has been said as to make us touch the whole 
subject with extreme caution, and while it is further admitt- 
ed that it is quite beyond the reach of present experimental 
research, yet it is believed that the use of the imagination is 
legitimate and tends toward the advancement of the science 
