A PIECE OF COAL. 1 89 
is made, only that furnaces are used to bake the coal 
in, and the gas is passed into large reservoirs till it is 
wanted for use. 
Fig- S3- 
You will find it difficult at first to understand how 
coal can be so full of oil and tar and gases, until you 
have tried to think over how much of all these there is 
in plants, and especially in seeds think of the oils of 
almonds, of lavender, of cloves, and of caraways ; and 
the oils of turpentine which we get from the pines, 
and out of which tar is made. When you remembei 
these and many more, and also how the seeds of the 
club-moss now are largely charged with oil, you will 
easily imagine that the large masses of coal-plants 
which have been pressed together and broken and 
crushed, would give out a great deal of oil which, 
when made very hot, rises up as gas. You may often 
yourself see tar oozing out of the lumps of coal in a 
fire, and making little black bubbles which burst and 
burn. It is from this tar that James Young first made 
the paraffin oil we burn in our lamps, and the spirit 
benzoline comes from the same source. 
