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These clays contain a larger proportion of peroxide of iron, 
than is found in the majority of the clays of the district. 
The clay underlying the Low Moor Better-bed Coal is of very 
good quality, and is made not only into fire-bricks, but into 
sanitary tubes, chimney pots, and terra cotta work of all 
kinds. To the east of Farnley it is found generally as a fire- 
clay; but at Farnley, Bowling, and Low Moor, it sometimes 
becomes a ganister. 
The fire-bricks made from the Better-bed clay are those 
in general use in this district, and are very beautiful in 
appearance. They are used in building all kinds of furnaces, 
from the fire backs of our homes, to furnaces for making steel. 
Many of the sandstones of this district are well adapted for 
furnace building where moderate temperatures are required, 
and before the fire-clays became generally used, a period of 
quite recent date, they were largely used, and are still in 
some instances. The ground ganister which is sold in 
Sheffield, often contains a considerable amount of sandstone 
ground with it when not required for the highest temperature, 
in order to prevent its breaking down. 
A rough stone from the Millstone Grit, found near Moor 
Allerton, Leeds, when ground into sand, makes a very good 
reverberatory furnace bottom, and the flag-stone in the 
quarry near the*Armley Midland Station, has been used to 
a considerable extent for building the furnaces of glass- 
houses. Newcastle fire-stones are still offered for sale for 
this purpose. A sandstone which is found at Deepcar also 
possesses fire-resisting properties, and I have no doubt that 
many other sandstones, if tested, would be found to resist 
heat to a considerable extent. The great drawback to their 
general use is their want of homogeneousness, for though the 
stone of one part of a quarry may resist heat well, that in 
another part might be only an indifferent quality. 
