Line the three plastic trays in a row. Put developer solution in the first tray, stop-bath solution in the second tray, and fixer in the third tray.

    If you have a safelight, you can use it to illuminate the room as you perform the rest of the experiment. If not, do everything in  total darkness:

1. Remove a sheet of print paper from the package. Re-seal the package to shield the rest of the paper from light.
2. Place the alpha ray source on the paper; be sure theopening is pointing downward. The rays must strike the emulsion side of the paper (the creamy smooth side).  Leave  the  source  in  place  for  at  least  one minute.
3. Set the alpha source aside, then slip the paper into thefirst tray (the developer solution). Leave the paper in the solution for about 90 seconds. Use the tongs to jiggle the paper every 15 seconds or so.
4. Pick up the piece of paper with your tongs, and trans-fer it to the second tray (the stop-bath solution). Leave the paper in that tray for 20 seconds.
5. Now with your tongs, transfer the paper to the thirdtray (the fixer solution). Leave it in the solution for at least five minutes. You can turn on the room lights after the paper has been in the third tray for 30 seconds.
6. Rinse the completed print under cold running waterfor at least five minutes.

   If you’ve followed these instructions carefully, the print will show a darkened circular area corresponding to the opening in the alpha source. The longer the source was left in contact with the paper, the darker the area will be.