SALTER — A CHRISTMAS LECTURE ON COAL 
229 
A LECTURE ON "COAL." 
By J. W. Salter, F.G.S. 
(Continued from page 183.^ 
I shall now give a few out of many specimens of coal, to show its 
composition, and so look at it in a practical point of view. For 
ordinary purposes, there is no doubt the " best" is the best ; but 
whether that best is Welsh, or Newcastle, or Scottish, I do not pre- 
tend to say ; for the various kinds of coal are suited for different 
purposes, and what may be refuse in one direction may be of the 
greatest use in another. 
In experiments undertaken with a view to determine what coals 
were best suited for our steam-navy, Sir Henry de la Beche and his 
associates tried nearly all the kinds known in Britain, and compared 
them too with those artificial fuels which are made up from coal- 
refuse, and are extremely valuable in their way. 
I can only give a few examples, and shall refer my young readers 
— they are older now than when the lecture began, and will not mind 
a little dry study — to the book itself, if they require more informa- 
tion.* 
They tried these coals to see how much they held of carbon, which 
supplies the heat ; of hydrogen, which gives the flame; of oxygen, which 
is worse than useless in the coal, though essential in the air that is to 
support the combustion ; and, lastly, the quantity of ashes left after the 
coal was consumed. Because it is clear that the coal which will give 
most heat, and make least smoke, and leave the least quantity of ash, 
provided it be not troublesome to manage, must be the best coal to 
bum. 
Now, our steam-navy coal requires all these good qualities. It 
must have the strongest heating power for the smallest quantity, and 
the less smoke it makes the better ; for that is not only all wasted 
carbon, but it betrays the position of the ship, when we would fain 
keep our enemy in the dark as to our movements. Moreover, it 
should be a coal that does not break or fly to pieces very easily ; for 
the rolling motion of a ship in a gale is very trying to the materials 
in her hold. Nor is a coal that burns too quickly, and makes the 
bars white hot, quite the right thing for men to stand in front of, 
for a stoker with such a grievance might make sad havoc with the 
engine. All has to be considered ; and I believe the government 
has rejected Welsh anthracite (so good for furnaces), and taken, in 
the main, Welsh caking coal. Out of three hundred thousand tons 
* Memoirs of the Geological Survev, vol. 2, part 2. 
