MADRAS JOURNAL 



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No. 11. —April, 1836. 



I,-— On Assaying Silver. — By Lieutenant Braddock. 



1. Until within these few years the art of assaying silver 

 remained almost stationary in Europe, for more than a cen- 

 tury and a half. I find by a work translated from the Ger- 

 man in 1683, that the furnaces, cupels, muffles, method of 

 preparing the assays, &c. were, at that time, nearly identical 

 with the methods practised at the present day. But, as 

 Sterne says " they manage these things better in France," 

 so we are indebted to the French for a recent improvement 

 in the assay of silver that places it on a footing, as it respects 

 precision of result, more in unison with the present improved 

 state of analytic science. 



2. To assay silver, that is, to ascertain the quantity o£ 

 pure silver contained in a given weight of bullion, there are 

 two ways ; by fire, and by aci<J. The method usually follow- 

 ed by English assayers is by fire, which is the old process ; 

 the new French method is by dissolving the silver in nitric 

 acid and precipitating it with a prepared standard solution of 

 common salt. I propose Erst to consider the old, and then 

 to proceed to detail the new process. 



3. The principle on which the assay by fire is founded is 

 this : a given weight, say 15 or 20 grains of silver, is mixed 

 with a certain quantity of lead, placed in a small crucible 

 made of the ashes of burned bones, and submitted for a cer- 

 tain time to a red heat in a small oyen which is fixed in a 



