1154 The Galvanic Battery. [No. 108. 



the exciting solutions. The membranous bag of the cylindrical Battery 

 is to be filled with the dilute solution of vitriol, so that this may be in 

 contact with the zinc rod, and the space between the membrane and 

 the copper is to be charged with the saturated solution of blue stone. 



In using the rectangular Battery, it is necessary to soak the paste- 

 board cases in the dilute solution of sulphate of soda, till they are 

 thoroughly saturated. Each copper cell is then to be made about two- 

 thirds full of the blue stone water, and subsequently the damped paste- 

 boards are to be respectively inserted. The solution of soda is then 

 to be poured inside the cases till the blue water rises to within an inch 

 of the mouths of the cells, care being taken that no extensive inter- 

 mixture of the two liquids takes place. In this case sulphate of soda 

 is in contact with the zinc, and sulphate of copper with the copper 

 elements of the battery. 



The cells having thus been charged, the small connecting cups are 

 then to be partially filled with mercury, and to complete the circuit 

 throughout the entire battery, the wire attached to zinc No. 1, is made 

 to dip into the cup of copper No. 2 ; the wire of zinc No. 2 into 

 the cup of copper No. 3 ; and thus the zincs of the series are to be 

 each connected with the adjoining coppers. By this arrangement, a 

 copper cup is left vacant at one extremity of the battery, and a zinc 

 wire unemployed at the other. These are usually called the poles, and 

 through them the power of the battery is directed as occasion may 

 demand. 



When the zinc plates are new, the solutions well made, and the con- 

 nections perfect^ indications of activity may usually be obtained a few 

 minutes after the battery has been charged. The junction of the two 

 poles by means of a short piece of copper wire having one of its ex- 

 tremities terminated by a small portion of very fine platinum or iron wire, 

 will afford immediate proof of the circulation of the galvanic current, 

 by the heating of the small wire to a degree dependent on the inten- 

 sity of the action. Should it appear that the ignition is not so deci- 

 ded as might be expected from the size of the battery, it is probable some 

 accidental interruption has occurred within the circuit, and the action 

 of part of the cells been thereby neutralized. To ascertain the locality 

 of this interruption, the test- wire is to be retained in contact with one 

 pole, and the platinum at its extremity made to communicate with each 



