“Now you can put your back against the door, Squire. We don’t want any visitors.” From a tiny glass bottle which he drew from his pocket, the Chief Constable extracted one of the ill-omened darts. “This is the one which wounded Miss Hawkhurst,” he explained, as he dropped it into a glass of water. “Now we’ll need to give it time.” He stirred it round occasionally; and gradually a faint bluish tinge communicated itself to the water. Ardsley was scrutinising the glass with deep interest, but his face showed nothing of the thoughts in his mind. “Now we add a drop of vinegar, Squire,” said Sir Clinton, suiting the action to the word. As the vinegar mixed with the solution, Wendover saw a change in the tint—a pale red replaced the original blue. “Now some washing soda, for a change,” said Sir Clinton, dropping in a crystal and swirling the liquid round in the glass. As he did so, the blue tinge returned to the solution. Ardsley nodded approvingly. “Litmus, obviously. That clinches it. You must be a bit of a chemist to have hit on that tip.” Sir Clinton made no reply, but he cautioned Wendover to bear the test in mind. “If that’s all you want, I’ll go back to Miss Hawkhurst,” Ardsley said, as soon as Sir Clinton ceased speaking. “We’re going back to the Grange, now,” Sir Clinton explained. “If you need me, you’ve only to ring up.” “I thought you were in a hurry,” Wendover said in some surprise when he found that Sir Clinton seemed to have nothing on hand on their return to the Grange. “You broke off your talk with Stenness on that excuse. Why not have finished it at the time, instead of trailing over there again later in the day?” “I’m worried about Miss Hawkhurst, Squire; and I prefer to get my news direct from Ardsley rather than over the ’phone.” “You didn’t get much out of him this morning,” Wendover complained. “And I can’t think why you put that man into the business at all. It seems to me tempting Providence. Why, he’s quite possibly the source of the original curare, for all you know; he’s one of the suspects.” “He’s not on my list of suspects, Squire; and if he’s on yours, you may score him off straight away. That’s definite. As to my using him, who could do the work better? What would a country G.P. make of Miss Hawkhurst’s case? Nothing whatever! You can’t expect rural medicos to be the last word in the study of out-of-the-way poisons. It’s not reasonable to ask it.” Wendover’s increasing disquietude found its relief in speech at last. “I can’t see what your aim is in this affair, Clinton. You say you know the murderer. Why don’t you arrest him at once? You claimed to know him days ago; and yet you did nothing. And now you’ve let things drift; and the result has been this attack on Sylvia Hawkhurst. Why, you’re responsible for that! You were criminally careless with these poison darts, leaving them lying about for anyone to pick up.”