nicotinic acid contaminated with vitamines.

Suzuki, Shimamura and Odake also used the phosphotungstic precipitation
method and claimed to have prepared the crystalline antineuritic substance
which they called oryzanin in the form of a crystalline picrate. Drummond
and Funk repeated this work, but were unable to confirm the Japanese
results. A group of British chemists (Edie, Evans, Moore, Simpson and
Webster) obtained an active fraction from yeast and succeeded in
separating this into a crystalline basic member belonging to the
pyrimidine group which they called _torulin_.

None of these three preparations have stood the test of analysis however
and their curative properties seem to lie in their greater or less
contamination with the actual substance, whatever it is. Numerous
modifications of the fundamental method for extracting the substance have
been planned and executed. Funk for example has shown that if the
phosphotungstic precipitate is treated with acetone it is possible to
separate it into an acetone soluble and an acetone-insoluble fraction and
that the curative fraction is in the latter. McCollum has reported that
while ether, benzene and acetone cannot be used to extract the B vitamine
from its source, benzene, (and to a slight extent acetone) will dissolve
the vitamine if it is first deposited from an alcohol extract on dextrin.
These observations have not yielded any further clew to the nature of the
substance.

Recently Osborne and Wakeman have proposed a modification which yields a
concentrate of high potency. Their method is to add fresh yeast to
slightly acidified boiling water and continue the boiling for about five
minutes. This process coagulates the proteins that are present and permits
their removal by filtration. The protein-free filtrate appears to contain