42 PHILOSOPHICAL TRANSACTIONS. [ANNO 17 Q6. 



metal. The other old metals were changed entirely into scoriae. The copper al- 

 layed with -sVth of its weight of tin was changed into scoria containing a little 

 copper; but the copper allayed with 4-th of tin was changed into scoria containing 

 a little copper, seemingly allayed with a much smaller proportion of tin than before. 

 The pyrometer pieces indicated degrees of fire, which varied between 18° and 21°. 

 The pyrometer piece in the coppel which contained the silver, and also that in the 

 coppel which contained the copper, denoted 20° of Wedgwood's scale, or about 

 3800° of Fahrenheit's scale. 



(c) A thin plate of each of the old metals being exposed to the flame of a candle 

 with the blow-pipe, a blue and green flame appeared, but soon disappeared, though 

 the fire of the candle was applied so as to keep the metal red-hot. The same kind 

 of blue and green flame was emitted from plates of these metals when they were 

 exposed to fire in open crucibles, before they were melted; but it disappeared in a 

 few seconds of time, though the fire was continued to be applied to keep the metal 

 red-hot; nor was any such flame produced when the metal was melted in open 

 vessels, or kept stirring when in a fluid state. 



(d) Each of the ancient metals being melted in close vessels, was then exposed 

 to the air, and stirred with an iron rod ; but none of them emitted any blue flame, 

 or white vapour, as was the case when brass was so treated. The following ex- 

 periment, to determine whether the ancient metal instruments contained any gold 

 or silver, was made, while I was present, by Mr. Bingley, Assay Master. 



(e) 50 grs. of each of these metals, and as much gun metal, and also the same 

 quantity of brass, were put into separate coppels, together with 150 grs. of lead, 

 under the muffle of an assay furnace: 150 grs. of lead were also put alone, by way 

 of test, into a separate coppel. The fire being kept up in the usual way, the brass 

 emitted a blue flame, and began to melt, discharging at the same time white 

 fumes; but soon after it was melted, the flame and white fumes disappeared. The 

 ancient metals, and also the gun metal, afterwards melted, and without sending 

 forth any flame, but a slight fume was seen when they were in fusion ; which was 

 particularly evident from the coppel containing the spear-head metal. This fume 

 was not seen to arise from the coppel which contained lead only; but the Assayers 

 observe it from charges of lead with silver, or lead with gold and silver, when much 

 air is admitted. 



' The process being finished, nothing was left in the coppels which contained lead 

 only, and lead and brass, except a just visible particle of silver; but in the other 

 coppels there remained about -*- of the original quantity of the ancient metals, and 

 of the gun metal: and therefore into each of these coppels 150 grs. of lead were 

 again introduced. The process being performed a 2d time, every particle of metal 

 was absorbed, excepting a just visible particle of silver in the coppels which con- 

 tained the celt, N° 2, the metal of the scabbard, and the gun metal : but there 

 was a much larger globule of silver in the coppel which contained the spear-head 

 metal. As the only metal which appeared to contain more silver than the test itself 



