"Love!" he cried cynically. "She did not love you. She only married you, it seems, to accomplish her own base and mysterious designs." Then, pacing the room from end to end, he added, "The more I reflect, the more apparent does it become that Ella Laing meant, by becoming your wife, to accomplish some great coup, but, prevented by some unforeseen circumstance, she has been compelled to fly, and in her haste overlooked this incriminating paper." This, too, was my own opinion, and taking from my pocket the whole of the letters that were in the escritoire, I placed them before him. "They are from your wife's mysterious lover," he observed, when a few moments later he had digested them. "Who he is there is no evidence to show. You suspect him, of course, to be the man she met in Kensington Gardens?" I nodded. A sigh escaped me. "Well," he went on. "Leave them with me. A calligraphic expert may possibly find some clue to the identity of their writer." Afterwards, he took up the broken envelope that had contained the treaty, carefully re-examining its edges by the aid of his large magnifying glass. "There is another curious fact that we must not overlook," he observed slowly. "While the seal has been broken this envelope has also passed through a `cabinet noir.' See, this edge bears unmistakable traces after wear in the pocket," and he handed it to me, together with his glass. The suggestion was startling, and one that I had entirely overlooked. The "cabinet noir" is a term well understood in diplomacy, but unfamiliar perhaps to the general public. Official documents of no great importance are often sent by post, and in most European countries this has led to the establishment of a "cabinet noir," in which the envelope is opened and its contents examined. The mode of procedure is interesting. The letter to be opened is first shaken well in such a way that the enclosure falls to one side of the envelope, leaving a space of about a quarter of an inch between it and the outer edge. This edge is then placed under an extremely sharp knife worked like a guillotine, care being taken to put it carefully at right angles to the knife, which is then brought down and cuts off a slip about one hundredth part of an inch wide. The envelope is now open, and the enclosure is extracted by a pair of pincers made for the purpose. After examination it is replaced, and the ticklish job of removing all trace of the opening has to be done. This is very ingenious. There are different pots of paper pulp mixed with a little gum, and each tinted a different colour to suit the various shades of paper that are operated upon. A very fine camel-hair brush is dipped into the pot containing the proper tint, and is then run carefully along the edges which have been cut open. They are then closed and left under a press for an hour or so, and after being smoothed with a flat steel instrument, it would take a very clever