Procedures Devise a system to place the camera on so that it takes a picture from the same place every time. Attach a piece of graph paper to a 15” x 20” pressboard, make sure you can see graph lines with the camera. Place a flat surface above a dish and adjust it to eye level of the camera. Using hot tap water fill both jars almost to the top. Add one half cup sodium carbonate to each jar, stir until no more will dissolve.