He pours some liquid onto the teaspoon and offers it to the chemist.
"Could you taste this for me, please?"
The chemist takes the teaspoon, puts it in his mouth, swills the liquid around and swallows it.
"Does that taste sweet to you?" says Paddy.
"No, not at all" says the chemist.
"Oh that's a relief" says Paddy.
Spoiler:
