8 
BULLETIN 164, U. S. DEPARTMENT OF AGRICULTURE. 
The ether extract is shaken with a strong solution of sodium bisul- 
phite, which treatment removes from the ether compounds of an 
aldehyde nature. After separating the bisulphite from the ether 
it is acidified with enough sulphuric acid completely to decompose it ; 
is freed from sulphur dioxide by blowing air through it, and is again 
shaken with ether. The ether extract obtained by this process on 
evaporation gave an oily residue. The residues secured from the soils 
taken from the vanillin-treated plots which had grown cowpeas, gar- 
den peas, and string beans had the odor of vaniuin. The residues 
were purified according to the method given in the paper cited. 
An aqueous solution of the purified residue from the three soils 
smelled strongly of vanillin. The aqueous solutions gave the color 
reactions characteristic of vanillin. Ferric chloride added to a por- 
tion of the solution gave a blue- violet color. When boiled with 
resorcinol and hydrochloric acid a red color resulted. The solution 
gave a violet color with, a mixture of sulphuric and hydrochloric acid 
and acetone water. Bromine water and ferrous sulphate gave a green 
color. Or the addition of the reagent of Foliu aud Denis, the solution 
having been made alkaline, with sodium carbonate, a clear blue color 
developed. 
As is shown from the above examination that this vanillin- treated 
field soil still contained the substance, it was tested in pots as to its 
qualities for growing plants. 
In this experiment wheat was grown in the greenhouse in paraffined 
wire pots, using the respective soils from the vanillin-treated plot and 
the check plots which in the field had grown cowpeas, garden peas, 
and string beans. The plants grew from December 11, 1913, to 
January 6. 1914. Two pots with 6 plants each were used for each 
soil. The results of the experiment are given in Table V. 
Table V. — Growth of wheat in pots of soil taken from the field plots six months ^after 
treatment with vanillin. 
Plot. 
Green weight of wheat plants on- 
Soil from 
plots un- 
treated. 
Soil from 
vanillin 
plots. ' 
Relative 
growth, 
check = 100. 
Cowpeaplot 
Garden pea plot 
String bean plot 
&rams. 
1.48 
1.47 
1.54 
Grams. 
1.09 
1.10 
1.10 
The table shows that the soils from the vanillin-treated plots were 
harmful to wheat in soil collected six months after the vanillin had 
been applied. 
A similar experiment was made with these soils, except that the 
crops grown in the pots were identical with those which had grown in 
