In my reference textbook , it was written that while making a simple voltaic cell , Alessando Volta took an electrolytic cell made of glass ad partially filled it by dilute sulphuric acid acting as an electrolyte. Then he took a bulb (or any other resistor) or galvanometer of 1.08 V and connected it by means of insulated copper wire to two electrodes inside electrolyte - one electrode made of copper and other made of zinc. Then he "assumed in his own time" that copper electrode acquired positive charge while zinc electrode acquired negative charge. My question is that firstly how can a voltaic cell work without connecting it to battery or cell ? Secondly how can he assume copper electrode to be positive and zinc electrode to be negative ? Why is it so ?