Kapi are suicide capsules used by Taurons, kept as a way of assuring that a person can die―or "return to the soil"―on their 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: "The Dirteaters").
In 88 BCH (12YR), 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").
In 58 BCH (42YR), Joseph forces kapi capsule into the Guatrau's mouth, in retaliation for the death of his own son (CAP: "Apotheosis").