742 BO REPORT—1863. | 
irregular intervals. Against this disadvantage, however, possessed by our 
coal, may be placed the extreme hardness and strength of the coke it pro- 
duces, which is thereby rendered capable of resisting the crushing effect of a 
high column of materials as they exist in our blast-furnaces. An experiment 
at the Clarence Works showed that a cube of coke 2 inches on a side sup- 
ported a weight of 25 cwt. when cold, and 20 cwt. when hot, before it was 
crushed. Dr. Richardson gives the following analyses of coal from this and 
other districts, the latter being given for the sake of comparison :— 
Percentage 
Locality. Sp.gr. Carbon. Hydro- Nitro- Sul- Oxygen. Ash. Coke left, 
gen. gen phur. by Coal. 
18 Samples, Newcastle 1256 82°15 5°31 1°35 24 5°69 3°77 60°67 ~ 
36.0 do. | Wales:..1.: 1315 83°78 4°79 98. 0°43 AIS) atga | 72°62 
8 do. Scotland...1'259 78°53 561 oo wil 9g'69 4703 54°22 
7. do. Derbyshirer‘19z2 79°68 4°94 I'41 Yor 10°28 265 59°32 
The purity of the coal is by no means an infallible indication of its fitness 
for the manufacture of a suitable coke for iron-furnaces. Not only is com; 
parative freedom from ash and sulphur indispensable, but we must have con- 
currently the power which depends on some circumstance we do not clearly 
understand, of producing coke sufficiently compact to come down to the region 
of fusion in our furnaces without being much crushed on its way. 
To form an idea of the extent to which ash and sulphur exist in the coke 
of the South Durham coal-field, the following analyses are extracted from the 
Clarence Laboratory journal :— ; 
Ash per cent. Sulphur per cent. 
5°86 one ees ig oe aa pla 0°58 
5°79 awe ae Ves ot dae 0°68 
754 O77 
g"00 oi 0°44 
8°33 =f 0°50 
As arule, 6 per cent. of ash and about ‘60 of sulphur may be considered 
as the average analytical results of the best coke of the district just quoted. 
Following the example of our neighbours abroad, plans have been introduced 
into this neighbourhood of submitting coal of an inferior description to a 
washing process, by which, where the earthy matter is not part and parcel 
of the coal itself, a very large quantity of impurity is easily removed. 
Limestone.—A very few words will exhaust this section of the subject. In 
certain districts the magnesian limestone, although differing little in colour, 
&e., from the rock in other localities, is nearly entirely carbonate of lime, and 
the mountain limestone almost invariably, from its purity, satisfies the con- 
ditions required by the iron-smelter. These two, but principally the latter, 
with a little chalk, brought by coasting-vessels as ballast, constitute the flux 
in the iron-furnaces. The following analyses from the Clarence Laboratory 
show the composition of 
Mountain Magnesian Chalk from 
Limestone Limestone. South of 
’ : | Harmby. Raisby Hill. England. 
Insoluble in Hydrochloric acid ...... Lolo Ns Cree Seer 295) (ayant cheers 1°96 
Peroxide of Iron and Alumina ...... EC} RP eee "AOU. ésvadeae 1°24. 
LAME «ss vadeesysvsssevevensyeeconSuensens BS qiokee sslecsa «gg GaGO2.,. heccavetages 53°34 
Magnesia: visctiiiasscsscstesessevdecsenoes TOS Lassen AS. eckeanaete et 63 
Uarbonionacid: @. shit iteh ee esiitens. 3 Pa ov RT ae ASAD | Vliet 42°99 
100°43 99°82 100°66 
The chalk contained 21 per cent. of water. 
Ironstone of the Lias.—It will be foreign to the intention of the present 
communication to attempt anything like a minute description of the district 
