ON THE DETRITAL TIN-ORE OF CORNWALL. 253 
The foregoing columns show that masses of J ews’-house-tin have, 
of late years, been discovered not only in every part of Cornwall 
west of the Fowey and the Camel* which has afforded stream-tin 
ore, but that they have been obtained also in Meneage, a part of 
the County in which no tin-ore, of any kind, has ever been found. 
A few of them have been procured from primitive smelting-sites, 
and one was met with on the coast; but no single example has 
ever yet been brought to light in the neighbourhood of an ancient 
highway. The shapes of these blocks are often so irregular as to 
defy mere verbal description ; but, perhaps, most of them show 
some approach to an oval on the upper side, thinning, however, 
from about the middle to the circumference on the lower ; resemb- 
ling, in fact, the rude pigs run from the small furnaces of native 
iron-smelters in the Himalaya,t or the lumps of iron cast—in 
hastily scraped pits—when the quantities of molten metal exceed 
the requirements of the founders. These Jews’-house blocks vary, 
from a few ounces to eighty pounds (Avoir.),in weight. The 
specimens hitherto described,t have generally been invested with 
lead-coloured crusts of the oxide of tin ; in some of which traces 
of chlorine§ have been detected. 
I have now to offer my grateful acknowledgements to the 
Noblemen and Gentlemen who have afforded me opportunity 
for these enquiries, and my warmest thanks to the Superin- 
tendents of works, and working-men, whose advice and assist- 
ance have enabled me to finish these—my last—labours in the 
* Whether the eastern moorlands were formerly sprinkled, in like 
manner, with masses of Jews’-house-tin we have now no means of ascertain- 
ing ; for it appears (MacuEan, Ante, p. 190) that some centuries ago they had 
been in great measure exhausted. 
+ Tyraill, Asiatic Researches, xv, p. 138. Herbert, /bid, i, p. 252. Hen- 
wood, Hxtracts from the Records of Government (Calcutta, 1855), p. 31. 
+ Borlase, Journal of the Royal Institution of Cornwall, i, Supplement, 
pp. 25, 26. Gregor, Cornwall Geol: Trans: i, p. 52. Michell, (J.), Manual 
of Mineralogy, p. 74. Collins, Journal of the Royal Institution of Cornwall, 
iii, (No. xiii), p. 83. Napier, bid, p. 84, Note. Percy, (Dr.), F.R.S. MS. 
§ During high winds and heavy rains the windows in West Cornwall 
are often slightly obscured by thin incrustations of common salt. 
F 2 
