The toxicity of elemental mercury is now widely known, which is why it has been phased out of use in everyday products from hats to thermometers to paints. However, mercury still has its use in the lab, particularly in organometallic chemistry where it is used to distinguish between heterogenous or homogeneous catalysis — known as the mercury drop test or the mercury poisoning test, among other names. As we continuously gain a better understanding of organometallic catalysis, observations of these mercury tests have often yielded unpredictable results, calling into question the validity of such experiments.