A single solitary drop lingered on the edge of the pipette. Sherlock had already mixed two chemicals in a beaker and now held the catalyst. He had only read about the effects, never seen them for himself, and he wanted to more than anything at the moment.
Drip.
Instantly the chemical reaction began, colours swirling, steam billowing from the beaker, and before he knew it, the experiment had gotten away from him, the exothermic reaction shattering the old and worn-out glass that was containing it and setting fire to the table. (The fire alarm had long since been thrown out because it constantly went off during Sherlock's experiments.)
"John," he shouted, eerily calm considering there was a massive fire within two feet of him. "Where's the fire extinguisher?"
John called back from the bathroom where he was shaving. "You used it in your last experiment!"
Sherlock looked around the room quickly, dousing a towel in water from the faucet and throwing it over the remnants of the beaker. This worked.
"Why did you want the fire extinguisher?" John shouted.
"No reason," Sherlock said, frowning at the mess of chemicals and glass.