Produits
par l'Electricite sur la Matiere Inorganique et sur la Matiere Vivante,'
_Travaux du Congres International de Physique, Paris, 1900_; and also
'On Similarities of Effect of Electric Stimulus on Inorganic and Living
Substances,' _British Association 1900_. See _Electrician_). To bring
out the parallelism in all details between the inorganic and living
response, I have in the following chapters used the method of
electro-motive variation employed by physiologists.

[15] By 'tin' is meant an alloy of tin and lead used as electric fuse.

CHAPTER XI

INORGANIC RESPONSE--MODIFIED APPARATUS TO EXHIBIT RESPONSE IN METALS

Conditions of obtaining quantitative measurements--Modification of the
block method--Vibration cell--Application of stimulus--Graduation of
the intensity of stimulus--Considerations showing that electric
response is due to molecular disturbance--Test experiment--Molecular
voltaic cell.

We have already seen that metals respond to stimulus by E.M. variation,
just as do animal and vegetable tissues. We have yet to see whether the
similarity extends to this point only, or goes still further, whether
the response-curves of living and in organic are alike, and whether the
inorganic response-curve is modified, as living response was found to
be, by the influence of external agencies. If so, are the modifications
similar? What are the effects of superposition of stimuli? Is there
fatigue? If there be, in what way does it affect the curves? And lastly,
is the response of metals exalted or depressed by the action of chemical
reagents?

#Conditions of obtaining quantitative measurements.#--In order to carry
out these investigations, it is necessary to remove all sources of
uncertainty, and obtain quantitative measurements. Many difficulties at
first presented themselves in the course of this attempt, but they were
completely removed by the adoption of the following experimental
modification. In the simple arrangement for qualitative demonstration of
response in metals previously described, successive experiments will not
give results which are strictly comparable (1) unless the resistance of
the circuit be maintained constant. This would necessitate the adoption
of some plan for keeping the electrolytic contacts at A and B absolutely
invariable. There should then be no chance of any shifting or variation
of contact. (2) There must also be some means of applying successive
stimuli