Read the excerpt from “Tools of the Spymaster."
James Jay's invisible ink did not become visible by heating. As he described it, his ink "would elude the generally known means of detection, and yet could be rendered visible by a suitable counterpart." Jay's invisible ink consisted of two chemicals. An agent used one chemical to write an invisible message. To read the message, the reader had to brush a second chemical on the paper; that chemical made the message visible. The two-bottle system, supplied by Jay, gave Washington the secure form of writing that he wanted.
Which statement includes explicit information from the excerpt?