118 
POPULAR SCIENCE REVIEW. 
distance of one hundred and fifty yards from the principal slag- 
heaps at Rio Tinto, the foundations of extensive buildings may 
be readily traced, and a little beyond them is a Roman cemetery 
in which thousands of interments must, at various times, have 
taken place. On a portion of this ground, over which are strewed 
the columns of a ruined temple, broken tombstones of ferru- 
ginous conglomerate are abundant ; but the inscriptions, which 
were on metal plates, of which indications are still visible, have 
in every case been removed. In this part of the cemetery all 
the graves have been long ago opened and their contents re- 
moved, but wherever the ground is disturbed in the surrounding 
oak wood, which covers several acres, stone cists are found con- 
taining burnt bones, pottery, glass vessels, leaden plummets,, 
links of iron chain, and pieces of litharge. 
The presence of litharge in these tombs, which are of undoubt- 
edly Roman age, with the occasional discovery of pigs of 
Roman lead, renders it more than probable that the then high 
price of gold and silver enabled the metallurgist of that day 
to extract with advantage the extremely small amount of these 
metals present in the pyrites of Rio Tinto. This was probably 
effected by liquation and the subsequent cupellation of the 
resulting lead. 
Forgetting the difference in the value of metals then and 
now, overlooking the cheap labour of Roman times, and taking 
for granted that work done so long ago must of necessity have 
been done badly, the idea has presented itself to various amateur 
metallurgists that such slags might be re-smelted with advan- 
tage. The analysis of an average sample of these Roman slags, 
by Mr. G. W. H. Clement, formerly chemist to the Rio Tinto 
Co., is however sufficient not only to show the great skill of these 
ancient artificers, but also to demonstrate the utter futility of 
any attempt to re- treat their residues. The results obtained 
were as follows : — 
Water 
1*05 
Silica 
. 32*02 
Alumina 
6-85 
Lime 
2-23 
Magnesia . 
•31 
Ferrous oxide 
. 50-02 
Feme oxide 
4*48 
Plumbic oxide . 
1-00 
Cupric oxide 
•18 
Metallic iron 
•45 
Ferrous sulphide 
1-35 
Alkalies 
•28 
100-22 
The above analysis indicates that in every ton of slag there 
are about 3 lbs. of copper, which, if it were possible to recover 
