He cautiously explored the boundaries of the heat. It became noticeable about eighteen inches above the drop and almost an inch to each side—an invisible slim vertical cylinder. Crouching close, eyes level with the top of the washbowl, he could make out the flame—a thin finger of crinkled light.
He noticed that a corner of the drop was seething—but only a corner, as if the heat were sharply bounded in that direction and perhaps as if the catalyst were only transforming the water to fuel a bit at a time.
He reached up and tugged off the light. Now he could see the flame—ghostly, about four inches high, hardly thicker than a string, and colored not blue but pale green. A spectral green needle. He blew at it softly. It shimmied gracefully, but not, he thought, as much as the flame of a match or candle. It had character.
He switched on the light. The drop was more than half gone now; the part that was left was all seething. And the bathroom was markedly warmer.
"Ernie! Are you going to be much longer?"
The knock hadn't been loud and his widowed sister's voice was more apologetic than peremptory, but he jumped, of course.
"I am testing something," he started to say and changed it mid-way. It came out, "I am be out in a minute."
He turned off the light again. The flame was a little shorter now and it shrank as he watched, about a quarter inch a second. As soon as it died, he switched on the light. The drop was gone.
He scrubbed off the spot with a dry washrag, on second thought put a dab of vaseline on the washrag, scrubbed the spot again with that—he didn't like to think of even a grain of the powder getting in the drains or touching any water. He folded the washrag, tucked it in his pocket, put the blue box—after a final check of the lettering—in his other coat pocket, and opened the door.
"I was taking some bicarb," he told his sister. "Thuringer sausage at lunch."