"What I say," answered Strause, who read these signs of agitation with pleasure. "It happens that I am in a position to prove my words. You know I was nursing Aylmer all day until you arrived and interfered. Your interference was unwarrantable; but I say nothing of that. I had been giving Aylmer his medicines, and happened to know exactly the amount in each bottle. The alterative medicine, as it is called, had just been renewed, but the bottle containing the opiate was more than half full. The opiate was in the smaller bottle, as you know. The alterative medicine was to be given in tablespoonfuls--two tablespoonfuls to a dose. At the time I gave up my charge of Aylmer to you there were in the larger bottle five doses, but the bottle which contained the opiate was a little less than half full. Do you follow me?"
"I hear you, but I cannot imagine what you are driving at."
"You will soon know. On the morning of the death you were terribly agitated. I rushed off to the poor lad's quarters when I heard the news, and found that you had left, saying that you would be round again presently. I went to the table where the medicines stood, and casually took up the bottle which contained the opiate. The moment I saw it I opened my eyes. The bottle was very nearly empty! Even allowing for your giving him a teaspoonful at a time, it was absolutely impossible that he could have taken anything like the amount which was now gone. I then looked at the other bottle, and found that only one teaspoonful had been taken from it since you had charge of the case. You follow me, don't you? In the bottle which contained the alterative medicine there were still _four doses_; in the bottle which contained the opiate there was not more than a _teaspoonful_ left. Beyond doubt what happened was this: you gave Aylmer, quite by mistake, two tablespoonfuls of the opiate--a dose which of course caused his death."
"You lie!" said Keith. "How dare you come to this room with that trumped-up story? I did not make a mistake with regard to the medicines. I was most careful, and I am prepared to swear in any court that I took two tablespoonfuls of the alterative medicine, which was in the larger bottle, and brought it to Aylmer between nine and ten o'clock that night."