"One of his men-servants is said to have tried that experiment," he replied.
"And what did the servant see ?" "A large white blind, drawn under the skylight, and hiding the whole room from view.

Somehow, the doctor discovered him--and the man was instantly dismissed.

Of course there are reports which explain the mystery of the doctor and his laboratory.

One report says that he is trying to find a way of turning common metals into gold.

Another declares that he is inventing some explosive compound, so horribly destructive that it will put an end to war.