Josephson shot a covert look at Kennedy.  “Yes,” he reiterated, “but I cannot see how it could be.  If the lights had become short-circuited with the bath, that might have thrown a current into the bath.  But they were not.  I know it.”

“Still,” pursued Kennedy, watching him keenly, “it is not all a question of current.  To kill, the shock must pass through a vital organ—­the brain, the heart, the upper spinal cord.  So, a small shock may kill and a large one may not.  If it passes in one foot and out by the other, the current isn’t likely to be as dangerous as if it passes in by a hand or foot and then out by a foot or hand.  In one case it passes through no vital organ; in the other it is very likely to do so.  You see, the current can flow through the body only when it has a place of entrance and a place of exit.  In all cases of accident from electric light wires, the victim is touching some conductor—­damp earth, salty earth, water, something that gives the current an outlet and—­”

“But even if the lights had been short-circuited,” interrupted Josephson, “Mr. Minturn would have escaped injury unless he had touched the taps of the bath.  Oh, no, sir, accidents in the medical use of electricity are rare.  They don’t happen here in my establishment,” he maintained stoutly.  “The trouble was that the coroner, without any knowledge of the physiological effects of electricity on the body, simply jumped at once to the conclusion that it was the electric bath that did it.”

“Then it was for medical treatment that Mr. Minturn was taking the bath?” asked Kennedy, quickly taking up the point.

“Yes, of course,” answered the masseur, eager to explain.  “You are acquainted with the latest treatment for lead poisoning by means of the electric bath?”

Kennedy nodded.  “I know that Sir Thomas Oliver, the English authority who has written much on dangerous trades, has tried it with marked success.”

“Well, sir, that was why Mr. Minturn was here.  He came here introduced by a Dr. Gunther of Stratfield.”

“Indeed?” remarked Kennedy colorlessly, though I could see that it interested him, for evidently Minturn had said nothing of being himself a sufferer from the poison.  “May I see the bath?”

“Surely,” said Josephson, leading the way upstairs.

It was an oaken tub with metal rods on the two long sides, from which depended prismatic carbon rods.  Kennedy examined it closely.

“This is what we call a hydro-electric bath,” Josephson explained.  “Those rods on the sides are the electrodes.  You see there are no metal parts in the tub itself.  The rods are attached by wiring to a wall switch out here.”

He pointed to the next room.  Kennedy examined the switch with care.

“From it,” went on Josephson, “wires lead to an accumulator battery of perhaps thirty volts.  It uses very little current.  Dr. Gunther tested it and found it all right.”