296 
THOMPSON YATES LABORATORIES REPORT 
The value of x is just half of that which would be found if the value of the poten- 
tial difference varied inversely with the concentration of the solution. Nor is there, as 
yet, any reason to modify the statement of this temporarily assumed relationship ; for 
one tact, and an unavoidable fact, spoils the value of the experiment from this point 
of view. The theoretical value required by the relation, 1*50, was almost attained in 
the experiment, but this was in the first five minutes, when the value rose to i - 40. 
After this the value has steadily fallen until in forty minutes it has reached a value as 
low as that reached by the nerve in Experiment V ("6 per cent. NaCl) in a time four 
times as great. 
Immersion in a dilute solution increases the value of the ' injury current ' as long as 
the immersion leaves the concentration of the '■internal solution ' of the nerve fairly intact: 
but prolonged immersion rapidly dilutes this internal solution and diminishes the value of the 
injury current, and the more dilute the experimental solution, the more rapid and the more 
final is this diminution. 
Such considerations as these may serve to justify the course adopted in the 
experiments of the next section, for the results of which a real quantitative value is 
claimed. In these experiments the time of immersion adopted is of five minutes 
duration, and no attention is paid to modifications produced by a more prolonged 
immersion than this. 
Since in this section alone the effects of prolonged immersion are studied, it 
seems better to include here a few experiments which completely shew the similarity 
in action upon the injury current of dilute solutions of the following electrolytes : — 
Sodium chloride. (Already given in Experiment IIa). 
Caustic soda. 
Hydrochloric acid. 
Potassium chloride. 
