SMEE'S BATTERY. 



41 



The nitro-muriate of platinum is easily prepared : take one part 

 of nitric acid, and two parts of hydrochloric acid (muriatic acid) ; 

 mix together and add a little platinum, either as metal or sponge ; 

 keep the whole at or near a boiling heat; the metal is then dissolved, 

 forming the solution required. 



Several alterations have been tried with a view to substitute a 

 cheaper metal than silver to deposit the platinum upon, but not with 

 much success. Cheap metals have also been coated with silver by 

 the electro-process, and then used. The most successful is a com- 

 position metal made of tin, lead, and a little 

 antimony, rolled into sheet and plated by 

 silver: this was found very convenient, be- 

 cause it could be easily bent into any required 

 shape, and it keeps its place without the 

 necessity of fixing in frames as required by 

 thin silver ; nevertheless, for constant work 

 these plates are found not to present any per- 

 manent advantage. 



Mr. Smee, in constructing his battery, 

 has been guided by the expense of the silver, 

 and therefore reverses the order of arrange- 

 ment introduced by Wollaston, by surround- 

 ing the platinized silver with the zinc. Fig. 

 18 represents a single cell of this form of 

 battery. A, is the jar containing the solution. Z, Z, the two 

 amalgamated zinc plates. S, the platinized silver plate. The 

 whole are suspended by a cross bar of wood ; and as it is essential 

 to the proper working of the battery 

 that the plates be always parallel to 

 one another, the wooden frame is 

 generally extended round the edge of 

 the thin silver plate, though it is not 

 so represented in the figure. One 

 of the clamps at the top of the wooden 

 bar is connected with the platinized 

 silver plate, and the other with the 19. 



pair of zinc plates. 



When intensity of electricity is required, it is necessary to use a 

 number of such cells, which may be arranged in a wooden frame, in 

 the manner shown by figure 19, where a b represent the two poles 

 of the battery, and c c, the wires by which the cells are connected 

 with one another. 



A superior form of compound Smee's battery, contrived by Ack- 

 land, is represented in figure 20. In this apparatus the plates are 

 all connected to a frame that can be elevated or depressed by means 



