354 A. LIVERSIDGE. 
Old Muntz Metal Sheathings. 
Mr. Cecil W. Darley, late Engineer-in-Chief for Harbours and 
Rivers, was kind enough to obtain for me some pieces of old 
muntz metal sheathing from the piles of wharfs undergoing repair. 
‘These were examined for gold and silver with the results given 
below. 
The method used for assaying was as follows :—In each case ’ 
2,000 grains, except where otherwise stated, of the sheathing in 
‘strips were dissolved in 1500 cc. of pure nitric acid (1 to 3 aq,), 
free from chlorine. After being cut into strips, the sheathings — 
were boiled in water, beaten, and scrubbed with a brass scratch 
brush so as to get rid of the dirt and scale as far as possible ; this 
probably also had the effect of removing part of the portion richest 
in gold and silver, as the assays of the separated scale show that 
it contains more of the precious metals than the body of the 
‘Sheathing. In most cases, the residue was grey and contained 
much lead. The clear nitric acid solution was decanted and 
filtered off and some sodium chloride solution added to ensure the 
precipitation of all the silver ; in the few cases where there was 
_ an additional precipitate of silver chloride, this was added to the 
gold and other insoluble matter on the filter. The solutions 
varied from green to blue. The filter and residue were dried, — 
wrapped in special assay lead free from gold, scorified, cupelled 
and checked in the usual way. In certain cases, the sheathing — 
was dissolved in sulphuric acid, (but, as the solution took place 
more rapidly in nitric acid, the latter was preferred) when @ yellow 
‘substance was generally found on the clock glasses used for cove 
ing the beakers ; this was found to consist of sulphur containing 
a little copper, the latter carried up mechanically by spirting» 
the sulphur was doubtless derived from the sulphuric acid by part 
of the acid being reduced by the nascent hydrogen given off from 
the zine of the alloy or more probably by the reaction between 
the hydrogen sulphide and sulphur dioxide evolved. 
Sheathing from an old trader, purchased in Sydney about 1874. 
‘The solution was made in sulphuric acid as already mentioned. 
