Dr. Pearson's Observations 
4 10 
but none of them emitted any blue flame, or white vapour, as 
was the case when brass was so treated. 
The following experiment, 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 grains of each of these metals, and as much gun me- 
tal, and also the same quantity of brass, were put into separate 
coppels, together with 150 grains of lead, under the muffle of 
an assay furnace : 150 grains 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 Assay ers 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 re- 
mained about one-third of the original quantity of the ancient 
metals, and of the gun metal: and therefore into each of these 
coppels 150 grains of lead were again introduced. The process 
being performed a second time, every particle of metal was ab- 
sorbed, excepting a just visible particle of silver in the coppels 
which contained the celt, No. 2, the metal of the scabbard, and 
