40 
minous shale was allowed to pass the German Customs Union without 
paying duty, because, though inflammable, it was not real coal. 
The essential peculiarities of coal as a mineral varied very much ; 
not merely in colour, weight, texture, hardness, fracture, &c., but also 
in its positive composition, in regard both to the amount of carbon it 
contained, and whether this was associated with gas capable of enter- 
ing into combination with carbon, or whether the amount of earthy 
and other impurities was so great that the heating powers were lost 
before they could be applied to the getting up steam in a boiler. 
While all true coal was almost entirely free from water, oxygen and 
hydrogen (originally derived from the water contained in these vegeta- 
bles) were at times present in such quantities as to interfere with the 
use of coal as a heat-producing agent. 
Coal, according to its quality and peculiarities, was generally 
classed as bituminous, steam, and anthracite, At the head of the first 
stood cannel (candle); next the Scotch parrot and splint. One 
variety of the cannel approximated closely to jet, but was more brittle 
and not so hard. These varieties were almost pure, and yielded large 
quantities of gas. Next stood the caking or Northumberland and 
Durham coals, succeeded by the cubic and what were called inland 
coals, which did not cake, contained less bitumen, and were considered 
inferior for household purposes. 
Steam coals, especially the Welsh coals, contained more carbon 
and less bitumen than the bituminous, and burnt freely without smoke 
where there was a great draught: hence their adaptability to steam 
purposes, 
The anthracite consisted almost entirely of carbon, and had been 
termed non-bituminous; while the steam coal had been called semi- 
bituminous. They were heavier than either of the others, took fire 
with difficulty, but gave off great heat with a strong draught. 
There were many points that might be considered, such as the 
position of coalin the geological series ; the different fossil remains 
other than vegetable associated with it; its probable age; rate of 
accumulation ; great areas of existence ; possible time to which our 
British coal would last, at the present or increased rate of consump- 
tion ; the various purposes to which coal was applied ; as well as the 
almost endless products derived from coal. He had simply endeavoured 
