Nitric Acid        1 lb. 
Muriatic Acid      2 lbs. 
Mercury            8 oz.

The acids should be first mixed and then the mercury slowly added until dissolved.  Clean the zinc with lye and then dip it in the solution for a second or two.  Rinse in clean water and rub with a brush.

Another method of amalgamating zincs is to clean them by dipping them in dilute sulphuric acid and then in mercury, allowing the surplus to drain off.

Commercial zincs, for use in voltaic cells as now manufactured, usually have about 4 per cent of mercury added to the molten zinc before casting into the form of plates or rods.

Series and Multiple Connections.  When a number of voltaic cells are joined in series, the positive pole of one being connected to the negative pole of the next one, and so on throughout the series, the electromotive forces of all the cells are added, and the electromotive force of the group, therefore, becomes the sum of the electromotive forces of the component cells.  The currents through all the cells in this case will be equal to that of one cell.

If the cells be joined in multiple, the positive poles all being connected by one wire and the negative poles by another, then the currents of all the cells will be added while the electromotive force of the combination remains the same as that of a single cell, assuming all the cells to be alike in electromotive force.

Obviously combinations of these two arrangements may be made, as by forming strings of cells connected in series, and connecting the strings in multiple or parallel.

The term battery is frequently applied to a single voltaic cell, but this term is more properly used to designate a plurality of cells joined together in series, or in multiple, or in series multiple so as to combine their actions in causing current to flow through an external circuit.  We may therefore refer to a battery of so many cells.  It has, however, become common, though technically improper, to refer to a single cell as a battery, so that the term battery, as indicating necessarily more than one cell, has largely lost its significance.

Cells may be of two types, primary and secondary.

Primary cells are those consisting of electrodes of dissimilar elements which, when placed in an electrolyte, become immediately ready for action.

Secondary cells, commonly called storage cells and accumulators, consist always of two inert plates of metal, or metallic oxide, immersed in an electrolyte which is incapable of acting on either of them until a current has first been passed through the electrolyte from one plate to the other.  On the passage of a current in this way, the decomposition of the electrolyte is effected and the composition of the plates is so changed that one of them becomes electro-positive and the other electro-negative.  The cell is then, when the charging current ceases, capable of acting as a voltaic cell.