Ripping Time by Robert Asprin & Linda Evans

He had been smiling steadily for the past hour or more, concealing his loathing for his current patient with an air of concerned understanding, while the bloody idiot of a Liverpudlian who’d appeared on his doorstep rambled on and endlessly on about his health, his illnesses, his medicines, his incessant chills and shaking hands, his itching skin and aching head . . .

It was enough to drive a sane man round the twist and gone. Which was where, in John Lachley’s private opinion, this pathetic cotton merchant had long since departed. Hypochondria was the least of Mr. James Maybrick’s woes. The fool daily swallowed an appalling amount of “medicinal” strychnine and arsenic in the form of powders prescribed by his physician, some doddering imbecile named Hopper, who should have known better than to prescribe arsenic in such enormous quantities—five and six doses a day, for God’s sake. And as if that weren’t enough, Maybrick was supplementing the powdered arsenic with arsenic pills, obtained from a chemist. And on top of that, he was downing whole bottles of Fellow’s Syrup, a quack medicine available over any chemist’s counter, liberally laced with arsenic and strychnine.

And Maybrick was so dull of mind, he honestly could not comprehend why he now suffered acute symptoms of slow arsenic poisoning! Grant me patience, Lachley thought savagely, the patience to deal with paying customers who want any answer but the obvious one. If he simply told this imbecile, “Stop taking the bloody arsenic!” Maybrick would vanish with all his lovely money and never darken Lachley’s doorstep again. He would also, of course, die somewhat swiftly of the very symptoms which would kill him, anyway, whether or not he discontinued the poisonous drug.