666 TREATMENT OF BATTERY. 



ledge outside a window. The terminal wires inay in that case" be 

 carried into the room by means of two holes through the lower 

 part of the sash, or two strips of copper, 10 cm long, 10 or 12 mm 

 wide, and O mm *5 thick, may be clamped between sash and window- 

 frame, and wires leading to the battery and into the room may be 

 soldered to the opposite ends of these. The two strips must of 

 course be kept carefully apart. 



When a Grove's battery is to be taken to pieces, first of all the 

 binding screws are removed from the zinc ; then the covers of 

 ebonite are lifted out of the porous cells, together with the attached 

 binding screws, platinum foil, and copper strips, allowing the 

 platinum to rest a/ little on the edge of the vessels that all the acid 

 may flow off, and finally these parts are separated from each other 

 by loosening the .clamps. 



In taking Bunsen's elements to pieces the binding screws are 

 also removed from the carbon pieces before these are lifted out of 

 the acid. The zinc plates are taken last of all out of the sulphuric 

 acid. 



Immediately after separating the parts, the zinc cylinders, binding 

 screws, ebonite covers, and copper strips must be rinsed in an ample 

 supply of water ; the zinc cylinders and covers are left for the 

 water to drip off, and thus to dry, but the screws and copper strips 

 should be wiped, after rinsing them, with a cloth, or dried as 

 quickly as possible in the sun or before a fire. The platinum foils 

 of Grove's elements are. rinsed with water, placed upon a flat support, 

 and wiped dry with a piece of soft cloth. The carbon, plates and 

 porous cells must be washed very carefully to prevent them being 

 spoiled. They are left for several days in water, which is oc- 

 casionally changed, and afterwards they are allowed to dry. If 

 some time after they have become dry a white efflorescence should 

 make its appearance upon the porous cells (either as a mealy coating 

 or an incrustation of fine needles,, or as a white far), it shows that 

 they have not been sufficiently soaked ; the same applies to the 

 carbon plates should they smell of nitric acid. In either case the 

 pieces must be placed again for some time in water. 



If the student can procure pans of sufficient size, and a suitable, 

 place for them, the best way is to preserve the carbon plates and 

 porous cells constantly under water, which in that case need only 

 be changed when the battery has been used. 



The inhalation of nitrous fumes may be avoided during the time 

 required for taking the parts to pieces by performing the whole 

 operation in the open air, or at least near the open window. The 

 pouring of the nitric acid from the porous vessels back into the 



