“But that may be the merest hypocrisy,” said Miss Murchison, rather warmly, for she was militantly rationalist. “I don’t trust these unctuous people.

“I didn’t offer that as proof of Hannah’s virtue,” said Wimsey, “but of Bunter’s unsusceptibility.”

“But he looks like a deacon himself.”

“You’ve never seen Bunter off duty,” said Lord Peter, darkly. “I have, and I can assure you that a hymn-book would be about as softening to his heart as neat whisky to an Anglo-Indian liver. No; if Bunter says Hannah is honest, then she is honest.”

“Then that definitely cuts out the drinks and the dinner,” said Miss Murchison, unconvinced, but willing to be open minded. “How about the water-bottle in the bedroom?”

“The devil!” cried Wimsey. “That’s one up to you, Miss Murchison. We didn’t think of that. The water-bottle – yes – a perfectly fruity idea. You recollect, Charles, that in the Bravo case it was suggested that a disgruntled servant had put tartar emetic in the water-bottle. Oh, Bunter – here you are! Next time you hold Hannah’s hand, will you ask her whether Mr. Boyes drank any water from his bedroom water-bottle before dinner?”

“Pardon me, my lord, the possibility had already presented itself in my mind.”

“It had?”

“Yes, my lord.”

“Do you never overlook anything, Bunter?”

“I endeavour to give satisfaction, my lord.”

“Well then, don’t talk like Jeeves. It irritates me. What about the water bottle?”

“I was about to observe, my lord, when this lady arrived, that I had elicited a somewhat peculiar circumstance relating to the water-bottle.”

“Now we’re getting somewhere,” said Parker, flattening out a new page of his notebook.

“I would not go so far as to say that, sir. Hannah informed me that she showed Mr. Boyes into his bedroom on his arrival and withdrew, as it was her place to do. She had scarcely reached the head of the staircase, when Mr. Boyes put his head out of the door and recalled her. He then asked her to fill his water-bottle. She was considerably astonished at this request, since she had a perfect recollection of having previously filled it when she put the room in order.”

“Could he have emptied it himself?” asked Parker, eagerly.

“Not into his interior, sir – there had not been time. Nor had the drinking-glass been utilised. Moreover, the bottle was not merely empty, but dry inside. Hannah apologised for the neglect, and immediately rinsed out the bottle and filled it from the tap.”

“Curious,” said Parker. “But it’s quite likely she never filled it at all.”

“Pardon me, sir. Hannah was so much surprised by the episode that she mentioned it to Mrs. Pettican, the cook, who said that she distinctly recollected seeing her fill the bottle that morning.”

“Well, then,” said Parker, “Urquhart or somebody must have emptied it and dried it out. Now, why? What would one naturally do if one found one’s waterbottle empty?”

“Ring the bell,” said Wimsey, promptly.

“Or shout for help,” added Parker.

“Or,” said Miss Murchison, “if one wasn’t accustomed to be waited on one might use the water from the bedroom jug.”

“Ah!… of course, Boyes was used to a more or less Bohemian life.”

“But surely,” said Wimsey, “that’s idiotically roundabout. It would be much simpler just to poison the water in the bottle. Why direct attention to the thing by making it more difficult? Besides, you couldn’t count on the victim using the jug-water – and, as a matter of fact he didn’t.”

“And he was poisoned,” said Mis Murchison, “so the poison wasn’t either in the jug or the bottle.”

“No – I’m afraid there’s nothing to be got out of the jug and bottle department. Hollow, hollow, hollow a11 delight, Tennyson.”

“All the same,” said Parker, “that incident convinces me. It’s too complete, somehow. Wimsey’s right; it’s not natural for a defence to be so perfect.”

“My God,” said Wimsey. “we have convinced Charles Parker. Nothing more is needed. He is more adamantine than any jury.

“Yes,” said Parker, modestly, “but I’m more logical, I think. And I’m not being flustered by the Attorney-General. I should feel happier with a little evidence of a more objective kind.”

“You would. You want some real arsenic. Well, Bunter, what about it?”

“The apparatus is quite ready, my lord.”

“Very good. Let us go and see if we can give Mr. Parker what he wants. Lead and we follow.”

In a small apartment usually devoted to Bunter’s photographic work, and furnished with a sink, a bench and a bunsen burner, stood the apparatus necessary for making a Marsh’s test of arsenic. The distilled water was already bubbling gently in the flask, and Bunter lifted the little glass tube which lay across the flame of the burner.

“You will perceive, my lord,” he observed, “that the apparatus is free from contamination.”

“I see nothing at all,” said Freddy.

“That, as Sherlock Holmes would say, is what you may expect to see when there is nothing there,” said Wimsey, kindly. “Charles, you will pass the water and the flask and the tube, old Uncle Tom Cobley and all as being arsenic-free.”

“I will.”

“Wilt thou love, cherish and keep her, in sickness or in health – sorry! turned over two pages at once. Where’s that powder? Miss Murchison, you identify this sealed envelope as being the one you brought from the office, complete with mysterious white powder from Mr. Urquhart’s secret hoard?”

“I do.”

“Kiss the Book. Thank you. Now then -”

“Wait a sec,” said Parker, “you haven’t tested the envelope separately.”

“That’s true. There’s always a snag somewhere. I suppose, Miss Murchison, you haven’t such a thing as another office envelope about you?”

Miss Murchison blushed, and fumbled in her handbag.

“Well – there’s a little note I scribbled this afternoon to a friend -”

“In your employer’s time, on your employer’s paper,” said Wimsey. “Oh, how right Diogenes was when he took his lantern to look for an honest typist! Never mind. Let’s have it. Who wills the end, wills the means.”

Miss Murchison extracted the envelope and freed it from the enclosure. Bunter, receiving it respectfully on a developing dish, cut it into small pieces which he dropped into the flask. The water bubbled brightly, but the little tube still remained stainless from end to end.

“Does something begin to happen soon?” enquired Mr. Arbuthnot. “Because I feel this show’s a bit lackin’ in pep, what?”

“If you don’t sit still I shall take you out,” retorted Wimsey. “Carry on, Bunter. We’ll pass the envelope.”

Bunter accordingly opened the second envelope, and delicately dropped the white powder into the wide mouth of the flask. All five heads bent eagerly over the apparatus. And presently, definitely, magically, a thin silver stain began to form in the tube where the flame impinged upon it. Second by second it spread and darkened to a deep brownish black ring with a shining metallic centre.

“Oh, lovely, lovely,” said Parker, with professional delight.

“Your lamp’s smoking or something,” said Freddy.

“Is that arsenic?” breathed Miss Murchison, gently.

“I hope so,” said Wimsey, gently detaching the tube and holding it up to the light. “It’s either arsenic or antimony.”

“Allow me, my lord. The addition of a small quantity of solute chlorinated lime should decide the question beyond reach of cavil.”

He performed this further test amid an anxious silence. The stain dissolved out and vanished under the bleaching solution.

“Then it is arsenic,” said Parker.

“Oh, yes,” said Wimsey, nonchalantly, “of course it is arsenic. Didn’t I tell you?” His voice wavered a little with suppressed triumph.

“Is that all?” inquired Freddy disappointed.

“Isn’t it enough?” said Miss Murchison.

“Not quite,” said Parker, “but it’s a long way towards it. It proves that Urquhart has arsenic in his possession, and by making an official enquiry in France, we can probably find out whether this packet was already in his possession last June. I notice, by the way, that it is ordinary white arsenious acid, without any mixture of charcoal or indigo, which agrees with what was found at the postmortem. That’s satisfactory, but it would be even more satisfactory if we could provide an opportunity for Urquhart to have administered it. So far, all we have done is to demonstrate clearly that he couldn’t have given it to Boyes either before, during or after dinner, during the period required for the symptoms to develop. I agree that an impossibility so bolstered up by testimony is suspicious in itself, but, to convince a jury, I should prefer something better than a credo quid impossibile.”