| 摘要 |
<p>Photosensitive salts and also a developer are incorporated with the conventional printing inks of the printing layer of the paper. When printing takes place the inks render an immediately visible image whilst the developer acts on the photosensitive salts which in the presence of light reduce to a stable metallic form to produce an indelible image. The paper is used for permanently preserved records, minutes, etc.</p> |
