A vial of liquid is a quest item used in Recruitment Drive during the Miss Cheevers challenge. It is first used on a metal spade head after adding cupric sulphate in order to heat it so that it sticks in a hole in a door. Afterwards, the spade head can be used as a door handle to open the door. The vial of liquid is then used again in the second part of the challenge to create a plaster cast of the bronze key. The liquid should be used with the tin (gypsum), which will create the tin (hardening).