"I guessed as much. I didn't fancy him from the first moment; and he was so blessed eager to have me begin by suspecting you two, that I smelt a rat at once. Oh, but he's been crafty enough in other things. Putting that devilish stuff on the ninth finger of the skeleton, and never losing an opportunity to get his poor old father to handle it and show it to people. It's a strong, irritant poison--sap of the upas-tree is the base of it--producing first an irritation of the skin, then a blister, and, when that broke, communicating the poison directly to the blood every time the skeleton hand touched it. A weak solution at first, so that the decline would be natural, the growth of the malady gradual. But if I'd found that phial in your room last night, as he hoped and believed I had done--well, look for yourself. The finger of the skeleton is thick with the beastly, gummy stuff to-night. Double strength, of course. The next time his father touched it he'd have died before morning. And the old chap fairly worshipping him. I suspected him, and suspected what the stuff that was being used really was from the beginning. Last night I drugged him, and then--I knew." "Knew, Mr. Cleek? Why, how could you?" "The most virulent poisons have their remedial uses, Captain," he made reply. "You can kill a man with strychnine; you can put him in his grave with arsenic; you can also use both these powerful agents to cure and to save, in their proper proportions and in the proper way. The same rule applies to Ayupee. Properly diluted and properly used, it is one of the most powerful agents for the relief, and, in some cases, the cure, of Bright's disease of the kidneys. But the Government guards this unholy drug most carefully. You can't get a drop of it in Java for love or money, unless on the order of a recognized physician; and you can't bring it into the ports of England unless backed by that physician's sworn statement and the official stamp of the Javanese authorities. A man undeniably afflicted with Bright's disease could get these things--no other could. Well, I wanted to know who had succeeded in getting Ayupee into this country and into this house. Last night I drugged every man in it, and--I found out." "But how?"