74 
THE PRINCIPAL FLOOR. 
quantity of white arsenic produced in Cornwall and Devon 
during the year 1893 was as much as 5,976 tons, of the value, 
at the mines, of 57,694^ 
With this series terminates the first division of the British 
ores; the remaining section, — including the ores of lead and iron, 
— being arranged in the recesses on the opposite side of the room 
to which we now cross. 
BRITISH ORES. Eastern Side. Wall Cases 43 to 56. 
Lead. 
Cases 43, 44, 45.- — Lead mining has been carried on in this 
country from a very early period. When in the possession of 
the Romans, many of the lead mines in 'Wales and England 
were worked, and considerable quantities of lead obtained, as we 
may infer from the immense accumulation of slags in Derby- 
shire, the Mendip hills and elsewhere. In the reigns of 
Henry VIII. and of Queen Elizabeth, especially in the latter 
reign, an impetus was given to British mining by the introduc- 
tion of a number of German miners. That mining for lead 
must, previously to this, have been extensively carried out is 
proved by the circumstance that Edward the Black Prince 
took several hundreds of the Derbyshire miners into Devonshire, 
and it is said that the result of his mining speculations in the 
west was the realisation of wealth sufficient to defray the 
expenses of his French wars. Many curious laws were made 
for, and special privileges were granted to, particular mining 
districts, as the King’s Field in Derbyshire, and the Myne-deeps 
— as the Mendips were formerly called. 
The principal lead-producing counties of England at the 
present time are Durham, Northumberland, Cumberland, West- 
moreland, Yorkshire, Derbyshire, and Shropshire ; in Wales 
Flintshire and Denbighshire ; and in Scotland, Lanarkshire and 
Dumfriesshire. Lead-ore is also raised in large quantities in the 
Isle of Man. The ores occur mostly in the Carboniferous Lime- 
stone, but some in Silurian slates and others in granite. 
The most important ore of lead is the widely diffused sulphide 
called Galena. In addition to the lead, of which the purest 
varieties of galena contain upwards of 86 per cent., various other 
metals are usually present in greater or less quantity. Of these, 
silver is the most important, and it is indeed highly probable 
that neither silver nor gold is ever entirely absent from 
galena. 
Following the specimens of galena are samples of other lead 
ores, less widely diffused than the sulphide, but many of them, 
nevertheless, of considerable importance. Foremost among these 
stands the carbonate of lead, called Cerussite or white lead ore. 
This mineral sometimes occurs in acicular or needle-shaped 
