first time he was no less happy than when he saw the
double paratartrate of soda and ammonia break up
unexpectedly. That was an unforeseen discovery on his
pathway; here, on the other hand, the discovery was
searched for and foreseen, which doubled the interest of
it. The paratartrate of cinchonine is not, moreover,
the only one which lends itself to such a separation:
that of quinicine is similar, but in this case it is the right-
handed tartrate which is deposited first.

We are, then, in possession of a second means of
separating the active components of a paratartaric acid.
Let us say immediately that it is by this method that
M. Bremer demonstrated the inactive malic acid of
Pasteur to be in reality a combination of the right- and
the left-handed acids. Let us say, also, that a third
means was conceived by M. Gernez in the laboratory
of Pasteur. It was incident to the preceding in that the
separate crystallization of the two tartrates was provoked,
not by differences in solubility, but by a suitable crystal-
line decoy introduced into the supersaturated solution.
With a decoy formed of right-handed tartrate one ob-
tained the crystallization of the right-handed tartrate;
with one of the left-handed tartrate, that of the left
tartrate. This was, then, under another form, it is true,
a dissymmetrical influence introduced to obtain the
separation.

Another means discovered by Pasteur is still more
curious and introduces us into the realm of life. It had
been known for a long time that lime tartrate left to
itself under water decomposes with the formation of
various products. One day Pasteur observed a solution
of right tartrate of ammonia placed in a flask in the
laboratory to be decomposing in the same way. The
liquid which was at first clear (let us keep this fact in
mind because we shall need it later) became clouded

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