336 



MINT 



loop of irou, suspended by a chain and cord from the ceiling, and passing the loop of 

 iron over a button on the end of the tongs, as shown at A, fig. 1520, supports the 

 weight of the pot, and regulates its height, while the foreman pours the metal into the 

 moulds, B, fixed in the frame, c, which runs on wheels in a tramway. Three pieces of 

 planed iron form two moulds, as shown in fig. 1521, where D*,E*,F 10 , show the form 



1520 



1521 



1522 



of these planed pieces, and the manner ot placing them together. The bars are solidified 

 immediately, and when all the moulds have been filled, they are taken to pieces, and 

 the bars plunged into cold water, as in the case of silver, to be described. From the 

 bars obtained from each pot, two pieces are cut off for assaying, by the assayers, the 

 bars being numbered according to the pot from which they were poured, and lettered 

 distinctively, according to the day on which they were melted. Should the assay 

 prove unsatisfactory, the metal is adjusted and re-melted. If the assays are satisfac- 

 tory, the bars are forwarded to the coining department. 



Previously to melting, pieces of charcoal are placed at the bottom of the pot for the 

 purpose of reducing any oxide that may be present in the alloy, because oxide of 

 copper renders some kinds of gold perfectly brittle and unworkable. In order to pre- 

 vent this charcoal from falling into the moulds with the gold the assistant holds a 

 piece of stick at the mouth of the pot, thus allowing the gold to flow while he detains 

 the charcoal. 



Silver is bought, through the brokers, by the Master of the Mint, either in the form 

 of foreign coin (5-franc pieces are preferred) or ingots ; and to the silver so obtained 



is added so much copper or pure silver 

 as shall bring the whole mass up to the 

 standard silver of the realm, which con- 

 sists of 220 parts of silver and 18 parts of 

 copper. The metal so arranged is weighed 

 out into charges of about 4,000 ounces for 

 the wrought-iron (plumbago is now used) 

 melting-pot, which is represented in Jig. 1522, 

 as seen in the furnace E, standing on the 

 ' bottom,' A, which rests on the fire-bars, and 

 is made partially cup-shaped, and filled with 

 powdered coke, that the bottom of the pot, 

 B, may be perfectly supported, while at the 

 same time it is protected from the current 

 of air which is supplied to the furnace. 

 Powdered coke, being a bad conductor, 

 prevents the free passage of heat from the 

 base of the pot to the 'bottom,' and the 

 consequent probable fusion of the two 

 through the agency of the oxide of iron, 

 which forms and accumulates whenever iron is repeatedly heated. D is the lid of the 

 pot ; and c, the muffle or funnel, against the sides of which the metal rests during the 

 process of fusion, to prevent its falling over into the burning coke. The pot, when 





