Another problem with Volta's batteries was short battery life (an hour's worth at best), which was caused by two phenomena. The first was that the current produced electrolyzed the electrolyte solution, resulting in a film of hydrogen bubbles forming on the copper, which steadily increased the internal resistance of the battery (this effect, called polarization, is counteracted in modern cells by additional measures). The other was a phenomenon called local action, wherein minute short-circuits would form around impurities in the zinc, causing the zinc to degrade. The latter problem was solved in 1835 by the English inventor William Sturgeon, who found that amalgamated zinc, whose surface had been treated with some mercury, did not suffer from local action.