Cleansing Bath (1973)

The wise criminal and his accomplices kidnap the beautiful Zea and prepare to put her in the bath that kills. Her husband manages to save her and it is the wise man who falls in his place and dissolves in the strange solution. The accomplices take to the cemetery a bathtub filled with a liquid in which the professor is dissolving. They spray the grave with said solution and that is when they are taken prisoner.

Unfortunately the movie Cleansing Bath is not yet available on HBO Max.