360 
Journal of Agricultural Research 
Vol. I, No. s 
The combined ether extracts were shaken with a strong solution of 
sodium bisulphite, which treatment removes from the ether compounds 
of an aldehyde nature. After separating the bisulphite from the ether 
it was acidified with enough sulphuric acid to decompose all the bisul¬ 
phite, was freed from sulphur dioxid by blowing air through it, and was 
again shaken with ether. On evaporating the ether extract at room 
temperature a more or less oily, viscous residue remained which had the 
odor of vanillin and gave the reactions of that compound. Crystals usu¬ 
ally separated from this residue after standing several days. 
When these crystals were obtained in sufficient quantity, they were 
purified by the method recommended for the examination of vanilla 
extracts. 1 The oily residue was treated several times with warm water 
and filtered, and the filtrate treated with a solution of lead acetate as 
long as a precipitate formed, and was then again filtered. The filtrate 
was shaken out several times with ether, and the combined ether extracts 
were evaporated. The residue usually crystallized readily, although it 
still contained traces of resinous matter. This resinous material could 
not be removed by taking up in ammonia, acidifying, and again shaking 
with ether as recommended in the method for vanilla extracts, but by 
recrystallizing from water several times and finally drying on a porous 
plate pure crystals were obtained. 
These crystals had a strong odor of vanilla, were in the form of needles 
or small prisms, and melted at 8o° to 8i° C., the melting point of vanillin. 
They were readily soluble in ether or alcohol, but were sparingly soluble 
in water. An aqueous solution gave the following reactions character¬ 
istic of vanillin or the group of compounds to which vanillin belongs: 
The addition of a solution of ferric chlorid gave a blue-violet color. 
Colors ranging from blue to violet are given by many hydroxy-benzene 
compounds. 
When boiled with resorcinol and hydrochloric acid, a red color was 
formed. This reaction is given by a number of aldehydes, including 
some sugars. 
When the crystals were treated with equal quantities of sulphuric and 
hydrochloric acids and with the addition of a drop of a dilute solution of 
acetone and the mixture then heated to ioo° C. for 15 minutes, a violet 
color was developed. 
On adding an excess of bromin water followed by the addition of ferrous 
sulphate, a blue-green color wras formed. This reaction is regarded as 
characteristic of vanillin, but does not seem applicable for colorimetric 
determination. 
When the reagent of Folin and Denis 2 w r as added and the mixture made 
alkaline with an excess of sodium carbonate, a clear blue color was 
1 Official and provisional methods of analysis, Association of Official Agricultural Chemists. U. S. Dept. 
Agr. Bur. Chem. Bui. 107 (rev.), p. 156, 1008. 
2 Folin, Otto, and Denis, W r . On phosphotungstic-phosphomolybdic compounds as color reagents. 
Jour. Biol. Chem., v. 12, no. 2, pp. 239-243,1912. 
