t in working order for some time by pouring in a little
vaseline to prevent evaporation of the liquid.

It will be shown further, in succeeding chapters, by numerous instances,
that any conditions which increase molecular mobility will also increase
intensity of response, and conversely that any conditions having the
reverse effect will depress response.

CHAPTER XII

INORGANIC RESPONSE--METHODS OF ENSURING CONSISTENT RESULTS

Preparation of wire--Effect of single stimulus.

I shall now proceed to describe in detail the response-curves obtained
with metals. The E.M. variations resulting from stimulus range, as has
been said, from .4 volt to .01 of that value, according to the metal
employed. And as these are molecular phenomena, the effect will also
depend on the molecular condition of the wire.

#Preparation of wire.#--In order to have our results thoroughly
consistent, it is necessary to bring the wire itself into a normal
condition for experiment. The very fact of mounting it in the cell
strains it, and the after-effect of this strain may cause irregularities
in the response.

For the purpose of bringing the wire to this normal state, one or all of
the following devices may be used with advantage. (1) The wires obtained
are usually wound on spools. It is, therefore, advisable to straighten
any given length, before mounting, by holding it stretched, and rubbing
it up and down with a piece of cloth. On washing with water, they are
now ready for mounting in the cell.

(2) The cell is usually filled with tap-water, and a period of rest
after making up, generally speaking, improves the sensitiveness. These
expedients are ordinarily sufficient, but it occasionally happens that
the wire has got into an abnormal condition.

[Illustration: FIG. 58.--EFFECT OF ANNEALING ON INCREASING THE RESPONSE
OF BOTH A AND B WIRES (TIN)
Stimuli (vibration of 160 deg.) applied at intervals of one minute.]

In this case it will be found helpful (3) to have recourse to the
process of annealing. For if response be a molecular phenomenon, then
anything that increases molecular mobility will also increase its
intensity. Hence we may expect annealing to enhance responsiveness. This
inference will be seen verified in the record given in fig. 58. In the
case under consideration, the convenient method employed was by pouring
hot water into the cell, and allowing it to stand and cool slowly. The
first three pairs of responses