Mr. J. Napier on Copper Smelting. 267 



racter of the qualities of coal used. The two last described as 

 weak we have selected as being veiy distinct in their composition : 

 the weakness of the first we believe to lie in the great amount of 

 volatile matters carrying away the heat in their expansion ; that 

 of the latter is its too close approximation to anthracite ; it does 

 not cake or swell, but lies as solid as a stone upon the bars. We 

 believe the physical character of the coke^ when the volatile 

 matters have passed off, is of great consequence. Taking the 

 analysis apart from these other conditions, it would be difficult 

 to say wherein lies the difference of quality. The following 

 table shows the amount of carbonaceous matters only, both in 

 the coke and the volatilized portion. 



From this table we observe a distinction in the composition of 

 the different qualities; a distinction, too, which a great many 

 analyses have borne out in respect to strong coal — that the car- 

 bon in the volatile matter should amount to from one-fourth to 

 one-fifth of the carbon in the coke. The great quantity of ash, 

 and of iron in the ash, of one of those termed too strong, causes 

 a fusion of the cHnker, and consequently a quantity of fused 

 glass to pass through the grate bars, making what the workmen 

 term a dirty coal, and increases their labour to keep the bars 

 clean, or rather the fire open, but is of no further disadvantage. 



Some of the workmen have a practice of keeping the coal they 

 are using wet, for the puqwse of making it cake better, and it 

 is supposed to give greater heat; some throw water into the 

 ash-pit to produce steam, which passes with the air through the 

 fire. These practices are no doubt the result of experienced 

 advantages. It is well known that if water be brought into contact 

 with red-hot charcoal or coke, or steam passed over these at a red 

 heat, carbonic oxide is formed and hydrogen liberated; which reac- 

 tion is probably the reason why water or steam passed into a fire 

 improves it for a short time for the reverberatory furnace. Plans 

 have been tried, and we believe with success, to give anthracite coal 

 some of the jjropeiiies of strong burning coal by admitting a 

 gentle current of steam to the fire ; but although the addition 

 of water to coals, or steam to a furnace, may improve a fire or 

 certain kiuds of coal, still water will never impart or make up 



