HOLGATE : SOME PHYSICAL PROPERTIES OF COAL. 
4G3 
verberatory chamber, up a cliimney some 80 or 40 feet in height, and 
finally appears at the top of the chimney. 
When made into coke much of it comes out of the oven in tlie 
same form as that in which it was thrown in. 
The Barnsley coals are nearl}' allied to the two kinds above- 
named. Nearly all coals are made up partly of water plants, and 
were formed under similar conditions to those named above, and 
more contain some fish remains than are generally supposed to do so, 
1 have not succeeded in finding any in the upper part of a thin 
seam known in this neighbourhood as the Crow Coal, of which, 
through its thinness, there is necessarily but a small quantity in the 
market. This coal is soft and very suitable for house fires. It con- 
tains but a small proportion of ash, gives a bright flame, the fire, 
without a forced draught, burning at almost a white heat. 
It is a good steam coal, but through its softness it burns away 
rapidly, and makes a great deal of smoke. This coal is of little value 
as a furnace coal compared with tliose previously named. It is so hot 
underneath the fire where the air rushes into it that the fire bars are 
melted. The flame produced however is so short that it scarcely 
reaches the iron, and does not fill the reverbatory chamber. Without 
trying it for gas-making we might safely conclude that it would yield 
an average amount of gas of an average illuminating power ; that an 
abundance of tar compounds would be given off, and that a soft 
spongy coke would reniani. 
Between these two kinds of coal there are many varieties. In 
some, as in the Middleton Main and the Haigh Moor, we get examples 
in which spores, though present, are not so numerous as in the 
Better Bed or the Hards of the ^liddleton Little. They contain 
more woody matter, and are sufficiently tough to retain a large size 
throughout the various handlings to which they are subjected from 
the time of being taken out of the mine to the time when they are 
thrown into the furnace. 
Their layers of bedding show an alternately dull and bright 
appearance ; they are very suitable for house fires, for raising steam, 
or for reverbatory furnaces. They are also suitable for gas-making, 
as they give off a gas of an illuminating power above the average, 
