110 
Iron . 
ter the coaks contain : Sly. what quantity of carbon they 
contain. Argillaceous and siliceous iron-stone require 
more fuel than the calcareous kind. Some calculations 
cf Mushet tend to shew that upon the average of iron- 
stones when roasted, 1 c wt. of the stone will require 1 cwt. 
of well burnt coaks, and that every ton of iron produced, 
consumes upwards of 2 1-2 ton of good coaks, and 672,000 
cubic feet of atmospheric air, at 300 cubic feet per lb. of 
Iron. 5 Ph. Mag. 366. Doubtless the wetter the ore is, 
and the damper the cinder is, the more coal is wasted* 
1 lb. of well burnt coaks when laid in water, will take up 
nearly two ounces of water in an hour’s time : this will 
require additional fuel to evaporate it ; but that is not all ; 
for as water contains so very large a proportion of its bulk 
of oxygen (upwards of 85 per cent.) it is manifest that this 
oxygen or the greater part of it, will combine with, and 
waste its due proportion of carbon or charcoal, and form 
carbonic acid gas, which requires in its formation 28 3-4 
per cent, of carbon. I say the greater part of the oxygen 
of the water ; because one part of it, will be employed in 
forming carburetted hydrogen with the hydrogen of the 
water, and bum away. Still the waste, as it seems to me* 
must be veiy great. 
It is manifest also, that the heat given out is not (other 
things being equal) exactly in proportion to the quantity 
of carbon in the fuel. Thus, I have generally understood 
that the charcoal of oak gives more heat than the charcoal 
of pine, but by Mr. Kir wan’s experiments the proportion 
of inflammable matter in pine charcoal, is beyond 
that of oak. Grains of charcoal necessary to alkalize 100 
grains of nitre. 
Charcoal . 
Of oak 
Of birch 
Of pine 
Of fir 
Of pitcoal 
Specific gravity » 
Number of grains 
,332 
- 
32 1 
,542 
22 
,280 
a 
24i 
» ,441 
- 
27 
t 44 " 
*T3 
19 
