1892-93.] NOTES o.v the amalgamation peocess. 357 



NOTES ON THE HISTORY OF THE AMALGAMATION 



PROCESS. 



Bv Robert ■ Dewar. 



(Read 27th April, iSg^;.) 



The amalgamation process, although generally believed to be modern, 

 is by no means so, but has really gradually developed through centuries 

 of use to its present position in metallurgical science-. We have reasons 

 to believe that the ancient Egyptians were acquainted with this process. 

 Indeed the attraction of mercury for other metals, especially gold and 

 silver, but apparently more e.specially gold, appears to have been known 

 from the most remote antiquity, and from time immemorial mercury has 

 been used in "streaming for gold," as the process was called. Vitruvius 

 remarks that gold might be recovered from embroidery and old clothes 

 by the use of mercury, and 1 liny mentions a process for the gilding of 

 brass and other metals by gold amalgam, remarking that mercury dis- - 

 solves gold, thus separating it from impurities, and on straining it through 

 leather pure gold is left ; to be sure it is really the gold amalgam that is 

 left in the leather. The process called streaming was used to collect the 

 fine gold disseminated through the sand composing the beds of streams 

 or rivers, and consisted in first washing the sand, then triturating the 

 residue with mercury and straining off the superfluous mercury through 

 leather. By miners it was used in a siinilar manner. The gold ore was 

 first ground and then triturated with mercury in mills ; but these mills 

 proved in the long run unsatisfactory as the residuum was found to retain 

 a large quantity of the gold and it was necessary to subject it to a roast- 

 ing, so that at the commencement of last century they were almost 

 universally abandoned. An opinion prevailed among chemists about 

 this time that unless both the silver and gold e.xisted in the pure state in 

 the substance under tre^atment by the- amalgamation process,-then the 

 mercury would fail to dissolve them, and hence the belief, which there 

 was sufficient reason for, that while fire treatment caused the ore to yield 

 the whole of its gold, the amalgamation process did not. This opinion 

 was supported by the most celebrated metallurgists of that period, such 

 •as Schliiter, Gellert, Wallerius and Cramer, the result being that the 

 amalgamation process was relegated to that class of jtrocesses described 

 .as not applicable on the large scale. It may be added that the streaming 

 process was, as used by different nations, exactly the same in procedure 

 as the above. 



