168 History of Mechanical InventioJis (^c. 



luable an alloy, has established at Vienna a manufactory, in 

 which he prepares this substance in large quantities. His 

 process is as follows : 



After breaking the nickel into pieces of the size of a small 

 nut, and dividing the copper and zinc, the three metals are 

 mixed, and put into a crucible, in such a manner that copper 

 may be both at bottom and top ; the whole is covered with 

 pulverized charcoal, and the crucible is heated in a wind fur- 

 nace. It is necessary frequently to stir the mass, in order 

 that the nickel, which is difficult to fuse, may combine with 

 the other metals and the alloy be homogeneous ; it must also 

 be kept a long time in fusion, even at the risk of separating a 

 small portion of the zinc by volatilization. 



The relative proportion of the three metals which compose 

 the packfong, should vary according to the use which is to be 

 made of it. That destined for the fabrication of spoons, forks, 

 &c. ought to contain 0.25 nickel, 0.25 zinc, 0.50 copper. 

 When it is to be used in ornamenting knives, snuffers, &c. it 

 should contain 22. nickel, 2S zinc, and 55 copper. The pack- 

 fong most suitable for plating consists of 20 nickel, 20 zinc, 

 and 55 copper. For objects which are to be soldered, as can- 

 dlesticks, spurs, &c. the best alloy is one of 20 nickel, 20 

 zinc, 57 copper and 3 lead. 



The addition of .020 to .025 of iron or steel, renders pack- 

 fong much more white, but at the same time more brittle. 

 It is necessary that the iron should be previously melted with 

 the copper. 



Packfong cannot be rolled without the greatest precaution. 

 Every time it is passed through the rollers, it must be heated. 

 to a cherry red and slowly cooled. When the sheets present 

 any rent, it must be hammered out before it passes again 

 through the rollers. 



The goldsmiths apply the pumice-stone to packfong, as to 

 silver. Colour is given to it, by dipping it in a mixture of 

 100 parts water and 14 sulphuric acid. 



When the turnings and filings of packfong are remelted, it 

 is best to add .03 to .04 of zinc, to replace that which has been 

 volatilized. 



M. Gersdorff sells his packfong at five francs per pound ; 

 nickel being sixteen francs.— /c?^?72. 



