should intervene.

The specimens Nos. 2, 3, 5, 22, and 23 contain sufficient iron to
render them available as iron ores, provided they occur in large
quantity. The copper present in No. 21a is too small in amount to
render it available as a source of that metal [Footnote: Analyses
of copper ore from Midian at the Citadel, Cairo, gave in certain
cases forty percent.]. If it is practicable on a large scale, by
hand-labour or other means, to separate the "copper mineral" (as
in b), it would be sufficiently rich in copper, provided the cost
of the transit were not too great.

The specimen No. 17 is only of scientific interest, as it gives
off an acid vapour when heated; and this substance may have been
used by the ancients in the separation of silver from gold by the
process termed "cementation."

I remain, dear Sir, yours very truly,

(Signed) JOHN PERCY, M.D., F.R.S.
Lecturer on Metallurgy at the Royal School of Mines, London.

Capt. R. F. Burton, etc.

Upon this able report I would offer the following observations.
We, who have travelled through a country like Midian, finding
everywhere extensive works for metallurgy; barrages and
aqueducts, cisterns and tanks ; furnaces, fire-bricks, and
scoriae; open mines, and huge scatters of spalled quartz, with
the remains of some eighteen cities and towns which apparently