Feb. 16,1914 
Benzene Derivatives in Soils 
361 
slowly developed. This reaches a maximum in a short time and remains 
constant for several hours, furnishing a reliable colorimetric method for 
the determination of vanillin. 1 
The method of isolating the compound from the soil, its crystalline 
form, odor, melting point, and the fact that it gave the characteristic 
reactions of vanillin are sufficient to establish its identity as vanillin. 
The quantity of pure vanillin obtained by this method from any of the 
soils examined was but a few milligrams from 25 kilograms. It was 
possible to obtain the vanillin in pure crystalline form from 4 of the 16 
samples. From some of the other samples crystals were obtained that 
gave the reactions of vanillin, but there were not enough for the separa¬ 
tion and determination of the melting point. Residues were obtained 
from all the samples having the odor of vanillin and giving two or more 
reactions for it. In each case where it was possible to separate vanillin 
in pure form the sample was a surface soil. 
An application of the colorimetric method of Folin and Denis was made 
to two samples, those from which the most vanillin had been obtained by 
alkaline extraction. One hundred grams of soil were finely ground and 
thoroughly extracted with warm alcohol that had been freshly distilled. 
The alcohol was evaporated, and the residue was taken up with warm 
water and filtered. Lead acetate was added to the filtrate as long as a 
precipitate formed. The solution was then filtered and the filtrate 
treated with the reagent of Tolin and Denis (a mixture of phosphotungstic 
and phosphomolybdic acids), followed by an excess of sodium carbonate. 
It was again filtered and made to a definite volume. The resulting blue 
solution was read in a colorimeter against a solution prepared in the same 
way from a standard solution of vanillin. Sample No. 1 gave 0.0010 per 
cent of vanillin, or 10 parts per million, while sample No. 2 showed 
0.00048 per cent, or 4.8 parts per million. 
Vanillin contains the radical methoxyl OCH 3 . In a previous paper 2 
it was shown that the methoxyl radical is present in many soils in suffi¬ 
cient quantity to be determined by the Zeisel method. 3 A determination 
of the methoxyl in samples Nos. 1 and 2 by this method gave, for sample 
No. 1, 0.065 per cent of methoxyl calculated to vanillin, and for sample 
No. 2, 0.050 per cent. 
Methoxyl is contained in a number of organic compounds and is a con¬ 
stant constituent of the lignocellulose of plants. The quantity obtained 
from these soils when calculated to vanillin is so much in excess of that 
actually obtained in the isolation from an alkaline extract, or that 
1 Folin, Otto, and Denis, W. A new colorimetric method for the determination of vanillin in flavoring 
extracts. Jour. Indus, and Engin. Chem., v. 4, no. 9, pp. 670-672, 1912. 
2 Shorey, E. C., and Eathrop, E. C. Methoxyl in soil organic matter. Jour. Amer. Chem. Soc., v. 33, 
no. 1, p. 7 S“ 78 » 1911. 
8 Zeisel, S. fiber ein Verfahren zum quantitativen Nachweise von Methoxyl. Monatsh. Chem., 
Bd. 6, 1S85, p. 989-996,1 pi. 1886. 
1 ■- 1 —' Zum quantitativen Nachweise von Methoxyl. Monatsh. Chem., Bd. 7, 1886, p. 406, 409. 1887. 
