1840.] The Galvanic Battery. 1155 



cell in succession, beginning with the most distant. Passing thus 

 along the battery, the total cessation or marked diminution of the heat- 

 ing power at any one point will indicate the accident to have taken 

 place there, and on examination it will usually be found that either 

 the connecting wires have slipped out of the mercury cups, or that their 

 extremities have become corroded, and unfit for insuring perfect metal- 

 lic contact, or that the connections have been imperfectly made. The 

 removal of the impediments will be indicated by the full development 

 of the power of the battery, in the intense ignition or fusion of the fine 

 test-wire. 



When batteries of a considerable number of cells are employed, it 

 increases materially their igniting power to make the cells act in pairs 

 by connecting two zinc plates directly with two copper cells, so that they 

 may act as one, but with double their former surface. 



Reference was formerly made to the propriety of occasionally 

 amalgamating the zinc plates and the extremities of the connecting 

 wires. With the former this is effected by washing the surface of the 

 zinc with a weak solution of sulphuric acid, and then applying a little 

 mercury, which immediately combines with the zinc, and renders ita 

 surface bright and smooth. Care must however be taken in handling 

 plates after amalgamation, as they become exceedingly brittle. To 

 amalgamate copper wire, the simplest plan is to brighten the surface, 

 and then to rub the brightened portion with a piece of soft leather to 

 which a little mercury has been made to adhere by means of a thin 

 coat of tallow. After continuing the friction for a short time, adhesion 

 of the mercury to the copper is effected. 



The mercury employed in these manipulations generally becomes 

 impure, it may however be purified again sufficiently for use, by 

 straining it through a piece of fine cloth of any kind, by which the dust 

 &c. is removed. 



When the object for which the battery was put in action has been 

 accomplished, the zinc plates should be immediately withdrawn from 

 the pasteboard cases, and well washed with pure water till all the 

 black deposit which will be found upon them is removed. 



Having recently had an opportunity of perusing Sir Michael Fara- 

 day's admirable " Researches in Electricity," I am indebted to that 

 work for the following remarks relative to some farther precautions to 



