 Another disadvantage is that a current has to be continually drawn to keep the two solutions from mixing by diffusion, so it is unsuitable for intermittent use.The German scientist Johann Christian Poggendorff overcame the problems with separating the electrolyte and the depolariser using a porous earthenware pot in 1842.In the Poggendorff cell, sometimes called Grenet Cell due to the works of Eugene Grenet around 1859, the electrolyte is dilute sulphuric acid and the depolariser is chromic acid.