1896 | TOXIC ACTION OF DISSOLVED SALTS 87 
hand only one physiologically active ion is present the effect- 
iveness of the solution is to be attributed to that one ion. Solu- 
tions of hydrochloric, nitric and sulphuric acids are nearly com- 
pletely dissociated when an equivalent in grams is dissolved in 
1000 liters of water. Hence such or more dilute solutions of 
these acids, when chemically equivalent quantities are dissolved, 
ought to have the same toxic effect, the Cl, NO, and SO, ions 
at such dilution being harmless. That these radicals are harm- 
less is shown by the fact that like concentrations of the sodium 
salts of these acids are harmless. 
EXPERIMENTAL METHODS. 
We have tested this point experimentally for the higher 
plants by ascertaining the strength of solution in which roots of 
the ordinary field lupine will just live. We have found that the 
limit for these acids is reached in case of a solution containing 
one equivalent in grams in 6400 liters of water. We may say, 
then, that one gram of hydrogen ions distributed through 6400 
liters of water will give a solution in which roots of the lupine 
will just survive. It is entirely immaterial at this dilution 
whether we take hydrochloric, nitric or sulphuric acids; the 
toxic action of the solutions is the same, provided they contain 
the same amount of hydrogen ions. The molecular weight in 
grams, or simply one gram-molecule of acid sulphate of potas- 
sium in 6400 liters, would contain as much ionic hydrogen as 
@ gram-molecule of hydrochloric acid, and should therefore 
have the same toxic effect. This has been confirmed by 
€xperiment. 
It seemed best to confine our first investigations to one 
order of plants, and, by reason of the nature of the ques- 
tion under consideration, to operate with objects which by 
Previous physiological study have become in a degree well 
known to botanists. It is for this reason that the seedlings of 
Lupinus albus 1. were selected. This seedling is remarkable 
for its straight, clean radicle, the ease with which uniform speci- 
mens can be obtained, and for its great sensitiveness to solu- 
