“Would two or more capsules of amyl nitrite constitute a lethal dose?” asked Penfield.
“They would be very apt to finish a feeble heart,” replied Stone. “Three capsules, if inhaled deeply would certainly kill a healthy person.”
Penfield showed the handkerchief to the physician. “Can a chemist tell, from the particles clinging to this handkerchief, how many capsules have been used?”
“I should say he could.” Stone looked grave as he inspected the linen, taking careful note of the letter “B” in one corner of the handkerchief. “But there is this to be considered—Turnbull may not have crushed those capsules all at the same time.”
“What do you mean?”
“He may have felt an attack coming on earlier in the evening and used a capsule, and in the police court used the same handkerchief in the same manner.”
“I see,” Penfield nodded. “The point is cleverly taken.”
Kent silently agreed with the coroner. The next instant Stone was excused, and after a slight pause the deputy coroner, Dr. Mayo, left his table and his notes and occupied the witness chair, after first being sworn. The preliminaries did not consume much time, and Penfield's manner was brisk as he addressed his assistant.
“Did you make a post-mortem examination of Turnbull?” he asked.
“I did, sir, in the presence of the morgue master and Dr. McLane.” Dr. Mayo displayed an anatomical chart, drawing his pencil down it as he talked. “We found from the condition of the heart that the deceased had suffered from angina pectoris”—he paused and spoke more slowly—“in examining the gastric contents we found the presence of aconitine.”