 The show courted mild controversy when it emerged that at least one  of the experiments was faked by a pyrotechnics department. The  alkali metals are known to react rapidly with water, producing  hydrogen gas and energy, with potentially explosive results. An  experiment was set up to demonstrate how these metals reacted by  dropping them in water, with the expectation that the heavier alkali  metals would be more potent. Lithium, sodium, potassium and rubidium  reacted with increasing potency. However caesium (the heaviest of  the alkali metals commonly available) simply sank to the bottom of  their "tank" (a bath) before it could react significantly, which was  far less dramatic than the other reactions suggested. The producers  had the bath wired with explosives and blown to pieces, and  presented this instead. According to a statement issued by the  production company, they frequently used pyrotechnics in this way.