MINT 



337 



charged, is allowed to remain in the furnace till the metal has fused, and the tempe- 

 rature has risen to a point little short of that which -would so far soften the wrought- 

 iron pot as to cause it to lose its shape. The pot is lifted by the tongs, T, of the crane 

 3, from the furnace, F, fig. 1523, (after the fire has been removed by displacing sonio 

 of the fire-bars), swung round and dropped into the cradle, ir, when it is secured by a 

 screw, which draws tight the band at tho top. The melted silver is then thoroughly 

 stirred with an iron rod ; and, all being ready, the frame of moulds, A, is run under the 

 cradle-stand so far as to allow tho rack, B, to work into the wheel N. The foreman 

 then, by means of the handle D, which communicates by E with the cradle in which 

 the pot is fixed, raises the pot, and tilts it so much as is necessary to pour the fluid 

 silver into tlio mould until it is filled ; he then lowers the pot, and waits while an 

 assistant by the handle o, connected with the cogwheel N, moves the moulds forward 

 as they are required to be filled. The moulds are ranged side by side in the frame, 

 and pressed firmly together by screws at the ends of the mould-frames, and secured 

 in front by two bars of iron, o, which fit into wedge-shaped grooves, slanting 

 forwards. 



1523 



The metal solidifies immediately, and the pot having been emptied, the carriage of 

 moulds is run on its wheels, Q, from under the cradle-frame, and the screws having 

 been loosened, the moulds are caused to fall to pieces, and each bar as it is exposed is 

 taken by tongs and plunged into cold water, as much to save time as to soften and 

 case-harden the bar by sudden cooling. The bars produced from the whole pot of 

 metal are numbered with a distinctive figure to designate the pot, and with two letters 

 to indicate the day's melting ; assay-pieces are then cut from the first, middle, and last 

 bars of the sot. 



The bars for different denominations of coins are proportioned in width so as to 

 admit of two rows of blanks being cut from the fillets produced from them. Space, 

 however, hardly admits of our giving detailed measurements ; but it may be expected 

 that a uniform thickness of -J an inch will at last be adopted by the Mint autho- 

 rities for all bars, both of gold and silver, as they now admit the advantage of 

 using -V-iuch bars for the gold coinage. 



The 'assay-pieces' are assayed to determine that they contain the proportion of 

 gold or of silver required by law, and it is assumed that these piece* give a fair 

 average of the bars ; hence, that the coin produced will be accurate, For a full 

 description of the processes adopted, see GOLD ; but it should be here noticed that 

 the operation has been much simplified by the improvements to which wo now invite 

 attention. 



Messrs. Johnson, Matthey, and Co. have invented a tray of platinum capsules or 



VOL. III. Z 



