Reviews—Kendall’s British Iron-ores. 310 
cent., and the Cape of Good Hope meteorite 15 per cent. of nickel. 
Although the Ovifak, Greenland, irons were at first considered to 
be true meteorites, subsequent investigations led to the detection of 
spangles and grains and lumps of iron inclosed in the eruptive rock 
itself, adjacent to the larger loose blocks of iron; so that it is possible 
that these masses of iron may have welled up with the igneous rock 
from some very deep-seated source of telluric energy, and that our 
own earth may, in its interior, possess a large supply of metallic 
iron in addition to the vast stores of oxides and sulphides distributed 
through its sedimentary crust. 
The compounds of iron, with various other substances which con- 
stitute the ores of iron, are very numerous. 
Of these, “hematite,” the anhydrous peroxide, known as red 
hematite, is that most commonly used for metallurgical purposes. 
Its composition is iron 70, oxygen 80=100. 
Hematite occurs in the Coniston Limestone (Ordovician) of 
Millom ; and in West Cumberland and Furness in the Carboniferous 
series. ‘‘Limonite” (hydrous peroxide or brown oxide), Magnetite 
(peroxide and protoxide of iron) and ‘‘Siderite” (or ‘“chalybite,” 
carbonate of protoxide of iron) in the Devonian rocks of Cornwall, 
Devon and Somerset. 
As one would naturally expect, with the development of our Coal- 
fields, the interstratified seams of clay ironstone of Coal-measure age 
were for a very long time, extensively worked in the South Wales 
Coal-field ; in Shropshire and North Staffordshire, in Northumberland 
and Durham, and in the Glasgow Coal area, and elsewhere. 
“Thirty-six years ago these rocks yielded four-fifths of the 
ore raised in Great Britain; but since the introduction of the more 
cheaply worked ores of the Secondary rocks, this proportion has 
been gradually reduced, until now these measures do not produce 
more than one-sixth of the total raised. Not only has there been 
this great relative fall, but there has been an absolute diminution 
in the production of clay-ironstone to the extent of about 5,000,000 
tons per annum. LHvery year this source of supply becomes less 
important; the only districts at present raising any considerable 
quantity being North Staffordshire and Scotland” (p. 145). The 
following table gives the 
CoMPARATIVE AMOUNT OF ORE RAISED AND ConsuUMED IN THE UnitED KinGpom. 
Tons in 1855. Tons in 1890. 
From the Secondary Rocks... ... ... 1,044,384 ...... 9,060,169 
#3 Carboniferous Rocks... ... 8,478,860 ...... 4,838,977 
55 Other Rocks esq essay) eee TORO coacon 54,792 
Morale.” Wetec 29058: 7 creme 13,953,938 
“Tt is thus seen that the output from the Coal-measures has, 
during the time embraced in these tables, fallen about 46 per cent., 
whilst that from the Secondary rocks has increased nearly 900 per 
cent. (p. 201).” 
“ Deposits in the Lower Lias.—The only deposit of iron-ore in 
these rocks that have been worked up to the present time occurs at 
Frodingham, in North Lincolnshire. For a long time it was con- 
