122 BOTANICAL GAZETTE [aucusT 
71. GALLIC ACID. 
(Begun January 23, 10 P.M.; closed January 24, 12 M.) 
Concentration 
gm, mol. per liter Length Remarks 
1e00 15.507 dead 
s2 24.0“ a 
UL oo 5 alive 
T2h00 28.0 “ 
Finally the action of the three mono-nitro-benzoic acids was 
investigated. Tables 72 to 74 show that the ortho compound is 
least poisonous, seedlings surviving in the concentration 6400, 
whereas in both the meta and para compounds the solutions 
proved fatal until the concentration 12,800 was reached. ihe 
degrees of dissociation of these acids at 1024 are 87.9 pet cen 
44.4 per cent. and 46.4 per cent. respectively. It is cleat that 
in case of the meta and para acids, the toxic effect at 12,800 
can no longer be due to hydrogen ions, and consequently mae 
be ascribed to the undissociated molecules and the anions; ' 
the concentration of the former is not great at this high dilution, 
it seems probable that the toxic action is mainly due t the 
anions. An investigation of the sodium salts will, of course, be 
necessary to decide this point definitely. Ortho-nitro-benzo¥ 
acid is practically completely dissociated at 6400. The anion 
of this acid are therefore less poisonous than hydrogen i 
The action of a solution of the sodium salt will very likely 
firm this. 
72. ORTHO-NITRO-BENZOIC ACID. 
(Begun January 16, 5 P.M.; closed January 17, 12 M.) 
Concentration 
gm, mol, per liter Length Remarks 
x00 19,0™™ flabby, dead 
we a 18.5 “ “ ““c oS 
sa00 36.0 “ apparently normal, living 
eae 29.0 “ “ “ 
coe 
OE oS Re hs 55s oa AL elas oe Re ee rae rea a 
