“This artificial poison reveals its nature on examination.  It is so disguised that one fails to recognise it, so subtle that it deceives the scientific, so elusive that it escapes the doctor’s eye:  experiments seem to be at fault with this poison, rules useless, aphorisms ridiculous.  The surest experiments are made by the use of the elements or upon animals.  In water, ordinary poison falls by its own weight.  The water is superior, the poison obeys, falls downwards, and takes the lower place.

“The trial by fire is no less certain:  the fire evaporates and disperses all that is innocent and pure, leaving only acrid and sour matter which resists its influence.  The effect produced by poisons on animals is still more plain to see:  its malignity extends to every part that it reaches, and all that it touches is vitiated; it burns and scorches all the inner parts with a strange, irresistible fire.

“The poison employed by Sainte-Croix has been tried in all the ways, and can defy every experiment.  This poison floats in water, it is the superior, and the water obeys it; it escapes in the trial by fire, leaving behind only innocent deposits; in animals it is so skilfully concealed that no one could detect it; all parts of the animal remain healthy and active; even while it is spreading the cause of death, this artificial poison leaves behind the marks and appearance of life.  Every sort of experiment has been tried.  The first was to pour out several drops of the liquid found into oil of tartar and sea water, and nothing was precipitated into the vessels used; the second was to pour the same liquid into a sanded vessel, and at the bottom there was found nothing acrid or acid to the tongue, scarcely any stains; the third experiment was tried upon an Indian fowl, a pigeon, a dog, and some other animals, which died soon after.  When they were opened, however, nothing was found but a little coagulated blood in the ventricle of the heart.  Another experiment was giving a white powder to a cat, in a morsel of mutton.  The cat vomited for half an hour, and was found dead the next day, but when opened no part of it was found to be affected by the poison.  A second trial of the same poison was made upon a pigeon, which soon died.  When opened, nothing peculiar was found except a little reddish water in the stomach.”

These experiments proved that Sainte-Croix was a learned chemist, and suggested the idea that he did not employ his art for nothing; everybody recalled the sudden, unexpected deaths that had occurred, and the bonds from the marquise and from Penautier looked like blood-money.  As one of these two was absent, and the other so powerful and rich that they dared not arrest him without proofs, attention was now paid to the objection put in by Lachaussee.