rotary power. Like the tartaric acid it carries over this
last property into its solutions, whether acid or alkalin,
but it presents this unforeseen peculiarity of rotating to
the left the plane of polarization when it is in a neutral
or an alkalin solution, and on the contrary of rotating
it to the right, and to a much greater extent, when it is
in an acid solution. In no case, however, has it ceased
to be asparagin unless the liquid has been heated or
the acids or alkalies have been too concentrated, and it
is possible by precipitation to recover it with all the old
properties. This proved that the rotary power of a
substance did not depend on itself alone and that if the
existence of this power had any significance for the ideas
on which Pasteur had taken his stand, its meaning and
importance were contingent and of a secondary order.

I have just said that, in order to leave intact the as-
paragin on which one is working, it is necessary not to
heat the liquids. Boiled with an alkalin solution, it is
transformed into aspartic acid. Does this acid keep
any of the rotary power of the asparagin? It is too little
soluble in water to make it possible to study it in aqueous
solutions. In solution in the alkalies it rotates to the
left: in chlorhydric or nitric acid it rotates to the right.

Another derivative of asparagin was still more interest-
ing to study; viz., the malic acid which one can obtain
from it by action of hyponitric acid. This malic acid
accompanies tartaric acid in the grape and therefore
should arouse curiosity. Experiment shows that in
regard to the rotary power it behaves a little like tartaric
acid, and that it sometimes even recalls it so much in its
properties that one is tempted to suppose for the two
acids origin from a common atomic grouping. Never-
theless, in their ensemble, the phenomena presented by
malic acid and the malates are more complicated than
those of tartaric acid and the tartrates. In the latter

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