but an inactive isomer of the active substance. The hydroxy-betaines which
Williams prepared in defense of his theory have been repeatedly tested but
have in general failed to confirm his view which stands today as an
interesting suggestion but without confirmatory evidence. Other attempts
by these authors to fraction their alkaline extract of fuller's earth have
been unsuccessful. It is of course well known that alkali acts upon the
vitamine destructively. On this account the authors of this method operate
as rapidly as possible and restore the alkali extract to a neutral or acid
medium quickly. The aqueous extract obtained from the earth in this manner
has been shown by Seidell to possess only about one-half of the vitamine
originally present in the solid but the vitamine in it is shown to be
fairly stable. Seidell has not yet determined how long it remains so.
Attempts to recover the vitamine from such aqueous solutions have however
totally failed to date. To quote Seidell from a recent publication:

By careful evaporation of the solution the products successively obtained
show more or less activity by physiological tests but in no case does the
resulting material possess the appearance or character which a pure
product would be expected to show. Solvents such as benzene, ethylacetate
and chloroform fail to effect a separation of active from inactive
material. In all fractioning operations the vitamine tends to distribute
itself between the fractious rather than to become concentrated in one or
the other.

The difficulties encountered by Seidell in this fractioning study have led
him to adopt Walsche's idea that vitamines are of the nature of enzymes
and hence present all the difficulties of identification and isolation of
those substances.

During 1920 Myers and Voegtlin attacked the problem. They have made a