Fig. 3. Side and bottom view of the acrylic lid. The slot labeled "open" on the left side of the bottom view allows outside air in. The square area labeled "open" in the center of the bottom view closes over the treated area so that the air drawn in through the slot can sweep the NH₃ volatilized from the treated area. The slit on the right side of the lid (side view) generates a uniform sweep of the treated area.