Dilution
Dilution was the addition of a chemical compound to another, in order to decrease the second compound's potency. 

In 2268, Doctor Leonard McCoy prescribed a thergen derivative diluted with alcohol to counter the effects of interphase. Dilution rendered the previously fatal derivative medicinal. ()

In 2370, Data believed the antidote for the Barkonians' radiation poisoning would still be effective, despite being diluted by well water. ()

In 2377, Chellick declared Gar's last supply of cytogenics to have been useless, as the shipment had contained expired lots and diluted samples. ()
Chemistry