Let her offer you a cup--and let me (under pretence of handing it) get possession of the poisoned drink.

Before she can cry Stop!--I shall be on my way to the chemist.
"The penalty for attempted murder is penal servitude.

If you still object to a public exposure, we have the chemist's report, together with your own evidence, ready for your son on his return.

How will he feel about his marriage-engagement, when he finds that Miss Carmina's dearest friend and companion has tried--_perhaps, with her young lady's knowledge_--to poison his mother?
"Before concluding, I may mention that I had a narrow escape, only two hours since, of being seen by Teresa on the stairs.
"I was of course prepared for this sort of meeting, when I engaged my room; and I have therefore not been foolish enough to enter the house under an assumed name.

On the contrary, I propose (in your interests) to establish a neighbourly acquaintance--with time to help me.