Sherlock thrust out an arm of the coat for examination.
"Powder. The poison was administered through the sprinkler system in powder form. And don't look like that, this is merely pigment."
Sherlock stomped his feet on the ground, in irritation. "And yes, Conner Kent's mother is not in fact his mother and Lulu Webster's parents were killed in a turf battle after threatening to go to the police. I'm bored, John."
If he hadn't been quite sure that Mrs. Hudson had hidden his revolver, he'd be shooting the wall about then.