To condense the purport of her demand, it was this: that I should test the efficacy of my new discovery by removing this objectionable obstacle from her path!
Of my subsequent behavior I offer no defense. I am not prepared to admit that I was forced into action by the forceful personality of my protegée; in fact, I state emphatically that a chance interview with the heir during one of his visits to Friar's Park led me to regard the matter in a new light and from a standpoint almost identical with that of Nahémah.
How warning was conveyed to Sir Burnham I know not, unless by some indiscretion of Nahémah, but, instead of returning to the public school from which he had come to Friar's Park, Roger Coverly was sent abroad in haste, accompanied by a private tutor. The date of his departure corresponded with that which I associate with the beginning of my downfall.
Nahémah threatened to present herself to her mother, and painfully aware that such a course (which, nevertheless, I recognized her to be quite capable of adopting) would spell disaster, I fell in with her wishes. Two months later we were established, Nahémah, Cassim and I, within two miles of the new residence of Roger Coverly and his tutor in Basle.
The circumstances attendant upon the death of Roger Coverly have hitherto been veiled in obscurity, and although Sir Burnham suspected the truth, in the first place he had no evidence, and in the second place, because of the existence of Nahémah, I knew that he dared not attempt to prove it.
Briefly, I had perfected that Chinese poison called in the northern provinces _hlangkûna_. By a series of dangerous experiments I had convinced myself that it was almost identical with _contarella_, the preparation made notorious by the Borgia family. Therefore I concluded that _contarella_ came to Rome from the East, possibly via Palestine. Inoculating with _hlangkûna_, I found, produced death in two hours (_contarella_--one hour and forty-five minutes) leaving no trace by which the means employed could be discovered. Self-inoculation by the subject was the method which I adopted--and which Cæsar Borgia had adopted before me; so that no chain of evidence existed.
All that was necessary was for a scarf, a collar or other article of apparel coming in direct contact with the skin of the subject, to be placed in my possession. (A glove was the Borgia's favorite medium.) It was painted with _hlangkûna_ and replaced. When worn, an intense irritation was produced and a cutaneous eruption which, if scratched even very lightly, resulted in a puncture of the skin sufficient to allow the inimical elements of the poison to obtain access to the system of the subject.