Between the two houses Kennedy paused, and for several moments appeared to be studying them.
We walked slowly back along the road to the town. As we passed the local drug store, Kennedy turned and sauntered in.
He found it easy enough to get into conversation with the druggist, after making a small purchase, and in the course of a few minutes we found ourselves gossiping behind the partition that shut off the arcana of the prescription counter from the rest of the store.
Gradually Kennedy led the conversation around to the point which he wanted, and asked, “I wish you’d let me fix up a little sulphureted hydrogen.”
“Go ahead,” granted the druggist good-naturedly. “I guess you can do it. You know as much about drugs as I do. I can stand the smell, if you can.”
Kennedy smiled and set to work.
Slowly he passed the gas through the samples of water he had taken from the two houses. As he did so the gas, bubbling through, made a blackish precipitate.
“What is it?” asked the druggist curiously.
“Lead sulphide,” replied Kennedy, stroking his chin. “This is an extremely delicate test. Why, one can get a distinct brownish tinge if lead is present in even incredibly minute quantities.”
He continued to work over the vials ranged on the table before him.