Dumb Witness - Agatha Christie [98]
“Obviously, though described somewhat differently by two different observers, the actual fact was the same. What it amounted to, shorn of spiritualistic significance, was this: On the night in question Miss Arundell’s breath was phosphorescent!”
Dr. Donaldson moved a little in his chair.
Poirot nodded to him.
“Yes, you begin to see. There are not very many phosphorescent substances. The first and most common one gave me exactly what I was looking for. I will read you a short extract from an article on phosphorus poisoning.
“The person’s breath may be phosphorescent before he feels in any way affected. That is what Miss Lawson and the Misses Tripp saw in the dark—Miss Arundell’s phosphorescent breath—‘a luminous haze.’ And here I will read you again. The jaundice having thoroughly pronounced itself, the system may be considered as not only under the influence of the toxic action of phosphorus, but as suffering in addition from all the accidents incidental to the retention of the biliary secretion in the blood, nor is there from this point any special difference between phosphorus poisoning and certain affections of the liver—such for example as yellow atrophy.
“You see the cleverness of that? Miss Arundell has suffered for years from liver trouble. The symptoms of phosphorus poisoning would only look like another attack of the same complaint. There will be nothing new, nothing startling about it.
“Oh! It was well-planned! Foreign matches—vermin paste? It is not difficult to get hold of phosphorus and a very small dose will kill. The medicinal dose is from 1/100 to 1/30 grain.
“Voilà. How clear—how marvellously clear the whole business becomes! Naturally, the doctor is deceived—especially as I find his sense of smell is affected—the garlic odour of the breath is a distinct symptom of phosphorus poisoning. He had no suspicions—why should he have? There were no suspicious circumstances and the one thing that might have given him a hint was the one thing he would never hear—or if he did hear it he would only class it as spiritualistic nonsense.
“I was now sure (from the evidence of Miss Lawson and the Misses Tripp) that murder had been committed. The question still was by whom? I eliminated the servants—their mentality was obviously not adapted to such a crime. I eliminated Miss Lawson since she would hardly have prattled on about luminous ectoplasm if she had been connected with the crime. I eliminated Charles Arundell since he knew, having seen the will, that he would gain nothing by his aunt’s death.
“There remained his sister Theresa, Dr. Tanios, Mrs. Tanios and Dr. Donaldson whom I discovered to have been dining in the house on the evening of the dog’s ball incident.
“At this point I had very little to help me. I had to fall back upon the psychology of the crime and the personality of the murderer! Both crimes had roughly the same outline. They were both simple. They were cunning, and carried out with efficiency. They required a certain amount of knowledge but not a great deal. The facts about phosphorus poisoning are easily learned, and the stuff itself, as I say, is quite easily obtained, especially abroad.
“I considered first the two men. Both of them were doctors, and both were clever men. Either of them might have thought of phosphorus and its suitability in this particular case, but the incident of the dog’s ball did not seem to fit a masculine mind. The incident of the ball seemed to me essentially a woman’s idea.
“I