170 New Apparatus for 'Reducing Chloride of Silver. 



was found that this could be dispensed with and only common 

 water used ; the action, however, is in this case a little retarded, 

 and does not become powerful until about two hours after the 

 battery is set. By using a part of the resulting liquor from a 

 previous reduction of argentic chloride, and which contains 

 chloride of ziuc, it has been found that the galvanic action sets 

 in very rapidly, and accelerates thereby the completion of the 

 reduction. 



No acid is used, and therefore the amount of zinc used in each 

 reduction has invariably been found to be almost the theoretical 

 quantity required to combine the chlorine of the argentic chloride 

 treated with the metallic zinc, in order to form chloride of zinc. 



The quantity of metallic zinc thus used was always from 21 to 

 25 per cent, of the weight of the argentic chloride reduced. 



The reduced silver is boiled out in acidulated water, iu order 

 to remove the basic and oxychlorides, and finally in pure water, 

 while still suspended in the silver loops. As soon as it is taken 

 off the last boiling it is immediately ready for the melting pot, 

 since the heat from the boiling water dries the porous mass of 

 silver sufficiently to allow of its immediate melting. The seven 

 zinc plates when first used weigh about 110 lbs. avoirdupoise, 

 the sis slabs of argentic chloride, of the dimensions already given, 

 weigh about 1100 ounces troy. 



The zinc plates are used over again until too thin for that 

 purpose, when they are remelted and cast into new plates. It 

 has been found that the quantity of zinc used is little, if at all 

 increased, by prolonging the time of connection with the silver 

 plates after the reduction is completed ; the whole apparatus, 

 when once set in operation, can therefore be left to itself until it 

 is found convenient to melt the reduced silver. 



While this apparatus reduces the argentic chloride much 

 quicker than if the latter is simply placed in contact with zinc or 

 iron plates, it obviates any handling of the argentic chloride from 

 the time the latter has been placed in the silver loops, until the 

 reduced silver is ready for the melting pot— advantages which 

 have been fully appreciated by those who formerly had to resort 

 to tedious and disagreeable manipulations. 



