Finding a piece of paper on which Mr. Field had begun a letter, only to afterward cast it aside, the detective wet the writing with a drop or two of water. At the same time he put a couple of drops on the writing of the letter received by the girl downstairs. The ink known to have been used by Mr. Field soon began to spread, as the water softened up the portion of the gum that had dried. But, on the ink of this other letter, it had no effect whatever, showing the absence of gum. To himself he said: “This little test shows absolutely that these two inks are not the same. Now, then, this letter to Barnes was written only two days ago and this one to the girl is supposed to have been penned yesterday. It is hardly likely that in this interim of a day Mr. Field changed his ink. Still, as it is possible, I must inquire into the matter. It is about what I expected, and if I fail to find steel pens around his desk, I will have a clear bill.” The most careful search of the desk failed to bring to light anything in the shape of a steel pen. When thoroughly satisfied that there were none, the detective smiled grimly, and said: “This proves the letter absolutely to be a forgery. It is in the writing of Mr. Field, or at least his penmanship has been so cleverly imitated as to deceive the best experts, so far as the strokes are concerned, but the villain who is so deft with the pen did not know that Mr. Field never used anything save a quill. If he had known it he would not have written this letter with a steel pen!” This was an absolute fact. The letter brought by the girl had been written with a steel pen, an article that, as shown by the evidence, Mr. Field never used and had a great antipathy for. Further, the ink in Mr. Field’s bottle was a black ink containing a great deal of “body,” or gum, while this ink with which the letter was written was a thin black ink made by an acid process. Hence, it stood proved that the letter was a forgery. And, if the letter was a forgery, what about the girl? Nick Carter’s opinion, an offhand one, without any evidence either one way or the other, was that she was an impostor, and in some way connected with the crime. Yet he hated very much to think of the girl in this way, for she certainly looked, and spoke, and acted like an honest, upright young woman. Still, up to the present moment hard, stern, cruel facts pointed at her with unwavering finger. One thing that he decided on before descending the stairs was that he could not any longer take Barnes into his confidence, and especially where the girl was concerned, for it was evident with half an eye that he had some great interest in her. On going downstairs he found them together in the parlor, and Barnes had so far prevailed on the girl that she had taken off her hat and wraps. Looking up, and giving the detective a bright glance, Barnes said: