plates were presumed lost, but for decades the Church of Jesus Christ of Latter-day Saints (LDS Church) published facsimiles of them in its official History of the Church. In 1920, one of the plates came into the possession of the Chicago Historical Society (now the Chicago History Museum). In 1966, this remaining plate was tested at Brigham Young University. The inscriptions matched facsimiles of the plate published contemporaneously, but the question remained whether this was an original Kinderhook plate, or a later copy. Though there was little evidence of whether the Kinderhook Plates were ancient or a contemporary fabrication, some within the LDS Church believed them to be genuine. The September 1962 Improvement Era, an official magazine of the church, ran an article by Welby W. Ricks stating that the Kinderhook plates were genuine. In 1979, apostle Mark E. Petersen wrote a book called Those Gold Plates!. In the first chapter, Peterson describes various ancient cultures that have written records on metal plates. Then Peterson claims: "There are the Kinderhook plates, too, found in America and now in the possession of the Chicago Historical Society. Controversy has surrounded these plates and their engravings, but most experts agree they are of ancient vintage." In 1980, Professor D. Lynn Johnson of the Department of Materials Science and Engineering at Northwestern University examined the remaining plate. He used microscopy and various scanning devices and determined that the tolerances and composition of its metal proved entirely consistent with the facilities available in a 19th-century blacksmith's shop and, more importantly, found traces of nitrogen in what were clearly nitric acid-etched grooves. In addition, Johnson discovered evidence that this particular plate was among those examined by early Mormons, including Smith, and not a later copy. One of the features of the plate was the presence of small dents in the surface caused by a hexagonally-shaped tool. Johnson noticed that one of these dents had inadvertently been interpreted in the facsimile as a stroke in one of the characters. If the plate owned by the Chicago Historical Society had been a copy made from the facsimiles in History of the Church, that stroke in that character would have been etched, like the rest of the characters. He concluded that this plate was one that Smith examined, that it was not of ancient origin, and that it was in fact etched with acid, not engraved, confirming Fugate's 1879