MAXIMUM SPECIFIC ELECTRICAL CONDUCTIVITY IN CHEMISTRY, 135 
Applying the hypothesis, the various solutions may be arranged into two groups: 
(A) Premaximal solutions and (B) Ultramaximal solutions, the concentration of the 
solutions in group (A) being somewhat less, and that of those in group (B) somewhat 
greater, than the concentrations corresponding to maximum conductivity. 
It was predicted that the premaximal solutions would. permit the hydrolysis of the 
amygdaline and of the potassium myronate, but that the ultramaximal solutions would 
inhibit or greatly retard the hydrolysis and consequent splitting up of the glucosides. 
The results actually obtained justified the hypothesis in a very satisfactory manner. 
With crushed bitter almonds all the premaximal solutions gave the smell of 
benzaldehyde quite distinctly within five minutes or less after mixing ; and also gave, 
with ordinary English mustard powder, a distinct pungency.* Conversely, none of 
the ultramaximal solutions gave rise, on mixing, to the smell of benzaldehyde, or to 
any distinct pungency, on standing ten minutes. When the mixtures are allowed to 
stand in loosely covered vessels for twelve hours or so, the difference between the 
two sets becomes very marked. 
Without the hypothesis of a tendency towards increased conductivity as a directing 
factor it does not appear possible to predict the behaviour of the various systems. 
When the mixtures made with solutions belonging to group (B)—and in which the 
reactions were inhibited—were mixed with sufficient water to bring the solutions to a 
concentration distinctly lower than that corresponding to maximum conductivity the 
reactions were found to proceed readily, even after long standing. This demonstrates 
that the enzymes are not rendered permanently inactive, and completes the proof 
that the tendency towards increased conductivity is a real directing factor in these 
cases. 
Another interesting observation bearing on the behaviour of sulphuric acid may be 
cited here. 
Professor A. J. Brown has discovered that the covering of the seeds of Hordeum 
vulgare acts as a peculiar semi-permeable membrane. He finds, for instance, that it is 
possible to concentrate dilute sulphuric acid by soaking the barley grain in the dilute 
acid, for the membrane, when undamaged, permits the passage of water, but not of 
sulphuric acid, into the interior of the grain. 
The preceding examples suggest an answer to the following question: What is the 
maximum concentration of sulphuric acid which can possibly be reached in this way ? 
The answer is: Not beyond the concentration corresponding to maximum conductivity, 
1.€. 30 per cent. H,SO,, for, as has been seen, the sulphuric acid tends towards increased 
conductivity, so that when the concentration reaches that corresponding to maximum 
conductivity, the tendency will oppose further concentration, as that would imply a 
decrease in the specific conductivity of the solution, which would thereby become ultra- 
* This statement requires modification in one case only, viz. so far as mustard and saturated solution of 
potassium iodide are concerned, for this solution has a marked disintegrative effect and appears to produce a deeper- 
going change which masks the tendency of the premaximal system. 
