Perform the experiment as follows:

	Label a series of six small glass tubes ("preciptin tubes") with the volume of antigen each will contain. Add the following volumes of antigen to the tubes: 0, 5, 20, 35, 50, 100µl. Add PBS to each tube to give a total volume 300µl. Add 100µl of antiserum to each tube and mix
Incubate at 37°C for 1hr (in waterbath) and then at 4°C (in refrigerator) for 1hr. Centrifuge tubes at 4000 rpm (2000g) for 10min in the bench centrifuge. Remove the supernatant and put aside in labelled tube for use in determining the point of equivalence. Keep the precipitate (pellet).