FRANCIS ON COAL DEPOSITS. 
133 
any effects of this kind much less marked than is the case 
with the closed-np apartments of Europe. 
The maximum quantity of sulphur allowable in coal for 
gas-making is usually fixed at 2 per cent. ; but even the 
smallest quantity is obnoxious. 
If is to be hoped that, as the Montserrat coal is obtained 
from deeper workings, the amount of this impurity will 
diminish. 
The quantity of ash or mineral matter yielded by the coal 
i i also somewhat high, but this is a fact of minor importance. 
In the event of the coal being used for gas-making, it will 
probably be found that the large quantity of ammonia yielded 
as a by-product will form a considerable item of remu- 
neration. 
The tables appended to this paper give the mean com- 
position of some of the chief British coals for comparison. 
Appendix. 
Percentage composition of some typical fuels, exclusive 
of water, ash and sulphur : — 
Carbon. 
Hydrogen. 
Oxygen and 
Nitrogen. 
Lignite 
66-96 
5-28 
27-76 
Earthy Coal ... 
74-20 
5-89 
19-91 
Brown ,, 
77-73 
7-84 
14-43 
Wigan Cannel 
85-81 
5-85 
8-34 
Hartley 
88-42 
5-61 
5-97 
Anthracite ... 
94-05 
3-38 
2-57 
Average composition of British coal, exclusive of water 
ash and sulphur : — 
Carbon. 
Hydrogen. 
Oxygen. 
Nitrogen. 
Welsh ... 89-43 
5-12 
4-38 
1-07 
Scotch ... 82-98 
5-92 
10-25 
0-85 
Newcastle 86-15 
5-56 
6-98 
2-31 
Derbyshire 82-68 
5-08 
10-48 
1-76 
Lancashire 83-14 
5-65 
10-14 
1-07 
