The doctor did not take any notice of this sneer, but, putting his hands in his pockets, faced round to the young man.

‘I give my evidence to-morrow,’ he said quietly, looking keenly at the young man, ’and I prove conclusively the woman was poisoned.  To do this, I must refer to the case of Adele Blondet, and then that implicates you.’

‘Pardon me,’ observed Vandeloup, coolly, removing some ash from his velvet coat, ‘it implicates Octave Braulard, who is at present,’ with a sharp look at Gollipeck, ‘in New Caledonia.’

‘If that is the case,’ asked the doctor, gruffly, ‘who are you?’

‘I am the friend of Braulard,’ said Vandeloup, in a measured tone.  ’Myself, Braulard, and Prevol—­one of the writers of the book you refer to—­were medical students together, and we all three emphatically knew about this poison extracted from hemlock.’

He spoke so quietly that Gollipeck looked at him in a puzzled manner, not understanding his meaning.

‘You mean Braulard and Prevol were medical students?’ he said, doubtfully.

‘Exactly,’ assented M. Vandeloup, with an airy wave of his hand.  ’Gaston Vandeloup is a fictitious third person I have called into existence for my own safety—­you understand.  As Gaston Vandeloup, a friend of Braulard, I knew all about this poison, and manufactured it in Ballarat for a mere experiment, and as Gaston Vandeloup I give evidence against the woman who was my mistress on the ground of poisoning Selina Sprotts with hemlock.’

‘You are not shielding yourself behind this girl?’ asked the doctor, coming close to him.

‘How could I?’ replied Vandeloup, slipping his hand into his pocket.  ’I could not have gone down to St Kilda, climbed over a wall with glass bottles on top, and committed the crime, as Kitty Marchurst says it was done.  If I had done this there would be some trace—­no, I assure you Mademoiselle Marchurst, and none other, is the guilty woman.  She was in the room—­Madame Midas asleep in bed.  What was easier for her than to pour the poison into the glass, which stood ready to receive it?  Mind you, I don’t say she did it deliberately—­ impulse—­hallucination—­madness—­what you like—­but she did it.’

‘By God!’ cried Gollipeck, warmly, ’you’d argue a rope round the girl’s neck even before she has had a trial.  I believe you did it yourself.’

‘If I did,’ retorted Vandeloup, coolly, ’when I am in the witness-box I run the risk of being found out.  Be it so.  I take my chance of that; but I ask you to keep silent as to Gaston Vandeloup being Octave Braulard.’

‘Why should I?’ said the doctor, harshly.

‘For many admirable reasons,’ replied Vandeloup, smoothly.  ’In the first place, as Braulard’s friend, I can prove the case against Mademoiselle Marchurst quite as well as if I appeared as Braulard himself.  In the next place, you have no evidence to prove I am identical with the murderer of Adele Blondet; and, lastly, suppose you did prove it, what satisfaction would it be to you to send me back to a French prison?  I have suffered enough for my crime, and now I am rich and respectable, why should you drag me back to the depths again?  Read “Les Miserables” of our great Hugo before you answer, my friend.’