Kapi are suicide capsules used by Taurons. Specifically, kapi are kept as a way of assuring that a person can die--or "return to the soil"--on his or her own terms, a point of honor in Tauron society (CAP: "The Dirteaters"). The poison in kapi is fast acting, capable of killing an individual within a few seconds. Other than a buildup of foam around the mouth, its effects are not visible (CAP: "Apotheosis").
In 88 BCH, William Adama Sr. taught his sons Joseph and Samuel Adama about the importance of kapi and of controlling one's return to the soil, at a time when the Tauron Civil War created the very real possibility of death at the hands of regime forces. A short time afterward, he was captured and brutally interrogated, and asked his sons for kapi when his torturers briefly stepped away, but the boys did not have enough time to find it for him (CAP: "The Dirteaters"). Thirty years later, Joseph forced a kapi capsule onto the Guatrau, in retaliation for the death of his own son (CAP: "Apotheosis").