Boraton

Sheba's Viper fires boraton at the fire in the landing bay ^{(TOS: "Fire in Space")}.

Boraton is a chemical used to extinguish fires. Apollo, Starbuck, and Sheba fly Vipers modified to fire boraton instead of lasers in an attempt to put out the fire in the landing pod ^{(TOS: "Fire in Space")}.

Original Series definition: a liquid that extinguishes fires ^{(TOS: "Fire in Space")}