decide as to the fullness or
sufficiency of proof... it only asks you one question: 'Have you an
inward conviction?'" "If," he said, "the actual traces of poison are a
material proof of murder by poison, then a new paragraph must be added
to the Criminal Code--'Since, however, vegetable poisons leave no trace,
poisoning by such means may be committed with impunity.'" To poisoners
he would say in future: "Bunglers that you are, don't use arsenic or any
mineral poison; they leave traces; you will be found out. Use vegetable
poisons; poison your fathers, poison your mothers, poison all your
families, and their inheritance will be yours--fear nothing; you will go
unpunished! You have committed murder by poisoning, it is true; but the
corpus delicti will not be there because it can't be there!" This was
a case, he urged, of circumstantial evidence. "We have," he said, "gone
through a large number of facts. Of these there is not one that does not
go directly to the proof of poisoning, and that can only be explained on
the supposition of poisoning; whereas, if the theory of the defence
be admitted, all these facts, from the first to the last, become
meaningless and absurd. They can only be refuted by arguments or
explanations that are childish and ridiculous."

Castaing was defended by two advocates--Roussel, a schoolfellow of his,
and the famous Berryer, reckoned by some the greatest French orator
since Mirabeau. Both advocates were allowed to address the jury. Roussel
insisted on the importance of the corpus delicti. "The delictum," he
said, "is the effect, the guilty man merely the cause; it is useless to
deal with the cause if the effect is uncertain," and he cited a case
in which a woman had been sent for trial, charged with murdering her
husband; the moral proof of her guilt seemed conclusive, when suddenly
her husband appeared in court alive and well. The advocate made a good
deal of the fact that the remains of the draught prescribed by Dr.
Pigache, a spoonful of which Castaing had given to Auguste Ballet,
had been analysed and showed no trace of poison. Against this the
prosecution set the evidence of the chemist at Saint Cloud, who had made
up the prescription. He said that the same day he had made up a second
prescription similar to that of Dr. Pigache, but not made out for
Auguste Ballet, which contained, in addition to the other ingredients,
acetate of morphia. The original of this prescription he had given to a