A double-depth plastic slide box is made by removing the bottoms of two standard 25–slide boxes and cementing the remaining frames together, bottom to bottom. A desiccant is placed in one box cover and fitted to the lower section of the cemented unit. A piece of screening is placed over the desiccant, the upper section filled with slides for radioautogaphy, and the empty cover applied to the top of the assembled box. Thus all slides are kept effectively and uniformly dehydrated during exposure.