L4 TOXIC SUBSTANCE EXCRETED BY PLANTS. 
Ammonium sulphate and dilute sulphuric acid also cause 
precipitation (of the sulphate ‘) of the substance after some time . 
so also do sodium acetate, ammonium (but not sodium) phosphate, 
ammonium molybdate (with nitric acid), ferric chloride (soluble 
in acetic acid). 
With greater concentration doubtless other substances than 
those here indicated would cause precipitation. 
The substance cannot be separated out by shaking its ammo- 
niated solution with amyl alcohol, chloroform, or either, hot or 
cold. It is also insoluble in alcohol. 
The solution produces after a few minutes a blue precipitate 
(ina green solution) with a mixture of ferric chloride and _potas- 
sium ferricyanide. It also decomposes potassium permanganate 
in the cold with production of a stable red precipitate (of the per- 
manganate ?) destroyed by boiling or excess of the reagent. 
Reduction also takes place with Fehling’s solution and with silver 
oxide in ammonia. 
It is easily decomposed by heating at 100°C when in the 
solid state. 
The solid dissolves in strong acids and Frohde’s reagent 
without colour, except in the case of nitric acid which gives a 
yellow solution. Potassium bichromate after strong sulphuric 
acid gives a green colour, changing to blue. 
The above reactions were given by all the solutions named 
in Table V and appear to indicate the identity of the toxic 
substance in the case of all plants. 
The substance is present in the solution in combination with 
citric acid. I could find no trace of phosphate or formate as stated 
to exist by Czapek, though the original solution before elimin- 
ation of the base, similates many of the reactions of these salts. 
Without having reference to the current literature on the 
subject it 1s impossible to compare the reactions above given with 
those obtained with any of the known alkaloids. Its marked 
insolubility appears to differentiate it from all the commoner 
alkaloids except pseudomorphine and rheodine with which it 
is improbable that it is identical. 
