(1) That ether waves produce molecular changes in matter.
(2) That the molecular or allotropic changes are attended with changes of electric conductivity, and this explains the action of the so-called coherers.
(3) That there are two classes of substances, positive and negative, which exhibit opposite variations of conductivity under the action of radiation.
(4) That the production of a particular allotropic modification depends on the intensity and duration of incident electric radiation.
(5) That the continuous action of radiation produces oscillatory changes in the molecular structure.
(6) That these periodic changes are evidenced by the corresponding electric reversals.
(7) That the "fatigue" is due to the presence of the "radiation product," or strained B variety.
(8) That by means of mechanical disturbance or heat, the strained product can be transformed into the normal form, and the sensitiveness may thereby be restored.
The method described above of detecting molecular changes is extraordinarily delicate, and is full of promise in many lines of inquiry in molecular physics. It is also seen that the phenomenon of contact sensitiveness, contrary to previous suppositions, is perfectly regular. There is no capriciousness in the response of sensitive substances to the external stimuli, which may be mechanical, thermal, or electric. The curves given above show it; but they fail to give a fair idea of the richness and variety of the molecular phenomena, seen as it were reflected in the fluttering galvanometer spot of light; of the transitory variations, of the curious molecular hesitation at critical times as to the choice of the structure to be adopted, and of the molecular inertia by which the newly-formed structure is carried beyond the position of stability, and the subsequent creeping back to the more stable position. The varieties of phenomena are unlimited, for we have in each substance to take account of the peculiarity of its chemical constitution, the nature of its response to ether waves, the lag and molecular viscosity. All these combined give to each substance its peculiar characteristic curve; it is not unlikely that these curves may give us much information as to the chemical nature and the physical condition of the different substances. I am at present trying to arrange an apparatus which will, by means of the pulsating galvanometer spot of light, automatically record the various molecular transformations caused by the action of external forces.
Before concluding, I take this opportunity of expressing my grateful acknowledgements to the Royal Society for the encouragement I
