266 Mr. Vivian on the Process of Amalgamation [ApriI, 



gara on the plates being about 3 cwt. the fire is lighted over the cast 

 iron cap or bell, and a stream of water is introduced into the cistern 

 which contains the iron pan. The fuel first used is turf, but 

 towards the end of the process they employ charcoal, with 

 which they fill up the whole of the vacant space within the case 

 of the furnace. As the iron bell becomes heated, the mercury 

 is volatilized, and falling to the lower part of the cap becomes 

 condensed, and collects in the iron pan, the water in which is 

 kept cool by the stream before noticed that flows through the 

 wooden cistern in which the pan stands. 



In this process every thing depends on a gradual increase of 

 temperature, and on a proper degree of heat being ultimately 

 given. If the furnace is heated too rapidly, a portion of the 

 mercury will remain united with the silver, which must infallibly 

 happen if any part of the compound is fused ; or too great a fire 

 may also occasion another bad effect — a portion of silver may 

 be sublimated with the mercury. On the other hand, a sufficient 

 degree of heat must be given to separate all the mercury ; for 

 if any portion remain combined with the silver, it would be lost 

 in the testing process that follows. The distilling process lasts 

 from eight to ten hours ; the person who attends upon it knows 

 when the whole of the quicksilver is extracted, by the cessation 

 of the sound made by the drops of that metal falling into the 

 water as it is condensed. On the following day, when the fur- 

 nace has become thoroughly cool, the outer door is opened, the 

 cap raised, the mercury in the receiver collected, and the silver 

 on the plates removed. The mercury is raised by a windlass, in 

 small boxes fitting into a square case or kibble, containing all 

 together about 5 cwt. and deposited in the iron vases in the 

 apartment over the distilling house, and adjoining the amalga- 

 mation room. It may contain a small portion of silver, but that 

 is of no importance, as it is again used for amalgamation with 

 that part of the quicksilver taken from the barrels, which had 

 passed through the filters as before described. The loss of 

 mercury in the distilling operation is about one-third of a loth 

 to the mark of fine silver obtained, which is nearly two percent, 

 on the quantity used. The silver on the plates should be in 

 ragged porous pieces. Some specimens are in fancy forms, 

 resembling trees, 8cc. ; and may be purchased at the works on 

 paying the value of the silver. The metal is for the most part 

 of the colour of silver ; but it is frequently tarnished with a 

 yellow or brown tint. It contains in fine silver from 12 to 13 

 ioths in the mark, or about 75 per cent. The other metals that 

 remain combined with it are such as were contained in the ore ; 

 as copper, cobalt, nickel, antimony, &c. To reduce the amal- 

 gamated silver to a compact state, and of uniform fineness, the 

 pieces taken from the plates are melted in a Passau crucible 

 previous to being refined, which is done at the neighbouring 

 smelting-work. The deliveries from the amalgamation-TTork to 



