is dissymmetry of construction but not molecular
dissymmetry.

One could put in the same category as quartz other
minerals or salts, such as sulphate of magnesium and
formate of strontium, substances having crystals with
hemihedral facets but the solutions of which are not ac-
tive. In short, no product of inorganic nature or of the
chemistry of the laboratory deviates the plane of polar-
ization of light when in solution; it is only the products
of living nature which have this property but they possess
it to a very marked degree and carry it with them when
they enter into combination with other substances.

Since then, the chemistry of synthesis has made
progress, and today, starting, like the plant, with water,
carbonic acid and ammonia, and putting into play only
the forces and ordinary resources of the laboratory, we
are able to manufacture artificially the majority of the
natural organic products. Is it necessary, therefore, to
change some of the conclusions which Pasteur announced
in 1850? Yes, one thing only which he did not foresee.
We are able now, by the aid of primitively inactive bodies
to manufacture active ones, to thus produce dissym-
metry and the rotary power in the molecule which we
construct. With inactive succinic acid we can ascend,
for example, to tartaric acid. But when a chemist
manufactures thus artificially the right-handed tartaric
acid he makes also necessarily and simultaneously the
left-handed form, so that the combination which comes
from his hands is inactive. Nature alone has the secret
of manufacturing one without producing the other. In
the grape, for example, she gives us commonly the right-
handed tartaric acid and not the left, or at least rarely
the left, since paratartaric acid, the combination of the
right and the left, sufficiently abundant at one time to
obstruct the works at Thann, has almost disappeared

-29-