| 摘要 |
<p>Feedback system on paper basic Rendering completely latent images visible, in an educational systems where pupil can find right answer to problems he has attempted, is effected by transferring image in form of vapour of, pref., dithiooxamide latent image that cannot be seen even with microscope and is stable over weeks or month, when it is developed by reactant such as salt of organic carboxylic acid which may be contained in wax pencil.</p> |
