522 PEAT AND TURF 



and which the spongy character of its mass renders it very difficult to get rid of. 

 There is nothing which reqtiires more attention than the collection and preparation 

 of turf; indeed, for practical purposes, this valuable fuel is absolutely spoiled as it is 

 now prepared in Ireland. It is cut in a wet season of the year ; whilst drying, it is 

 exposed to the weather : it hence in reality is not dried at all. It is very usual to 

 find the turf of commerce containing one-fourth of its weight of water, although it 

 then feels dry to the hand. But let us examine what affects the calorific ptTwer. 

 1 Ib. of pure dry turf will evaporate 6 Ibs. of water ; now, in 1 Ib. of turf as visually 

 found there are | Ib. of dry turf, and Ib. of water. The % Ib. can only evaporate 

 4 Ibs. of water ; but out of this it must first evaporate the ^ Ib. contained in its 

 mass, and hence the water boiled away by sucli turf is reduced to 4J Ibs. The loss is 

 here 30 per cent., a proportion which makes all the difference between a good fuel and 

 one almost unfit for use. When turf is dried in the air under cover it still retains 

 one-tenth of its weight of water, which reduces its calorific power 12 per cent., 1 Ib. of 

 such turf evaporating 5jlbs. of water. This effect is sufficient, however, for the great 

 majority of objects ; the further desiccation is too expensive and too troublesome to 

 be used, except in special cases. 



The characteristic fault of turf as a fuel is its want of density, which renders 

 it difficult to concentrate, within a limited space, the quantity of heat necessary for 

 many operations. The manner of heating turf is, indeed, just the opposite to an- 

 thracite. The turf yields a vast body of volatile inflammable ingredients, which 

 pass into the flues and chimney, and thus distribute the heat of combustion over 

 a great space, -whilst in no one point is the heat intense. Hence, for all flaming 

 fires turf is applicable ; there is, however, as some experiments made on Dartmoor 

 show, some liability to that burning away of the metal which may arise from the 

 local intensity of coke. If it be required, it is quite possible to obtain a very intense 

 heat with turf. 



The removal of the porosity and elasticity of turf, so that it may assume the 

 solidity of coal, has been the object of many who have proposed mechanical and other 

 processes for the purpose. It has been found that the elasticity of the turf-fibre pre- 

 sents great obstacles to compression, and the black turf, which is not fibrous, is of 

 itself sufficiently dense. 



Hot merely may we utilise turf in its natural condition, or compressed or impreg- 

 nated with pitchy matter, but we may carbonise it, as we do wood, and prepare turf- 

 charcoal, the properties of which it is important to establish : 



By heating turf in closed vessels loss is avoided, but this process is expensive, 

 and there is no compensation id the distilled liquors, which do not contain acetic 

 acid in any quantity. The tar is often small in proportion ; hence the charcoal is 

 the only valuable product. Its quantity varies from 30 to 40 per cent, of dry turf. 

 The products of the distillation of 1,157 Ibs. of turf were found by Blavier to be 

 charcoal, 474 Ibs., or 41 per cent. ; watery liquid, 226 Ibs., or 19'3 per cent. ; gaseous 

 matter, 450 Ibs., or 39 per cent. ; and tar, 7 Ibs., or 6 per cent. ; but the proportion 

 of tar is variable, sometimes reaching 24'5 per cent, when the turf is coked in close 

 vessels. 



The economical carbonisation of turf is best carried on in heaps, in the same 

 manner as that of wood. The sods must be regularly arranged, and laid as close 

 UK possible; they are the better for being large, 15 inches long, by 6 broad, and 

 6 deep. The heaps, built hemispherically, should be smaller in size than the heaps 

 of wood usually are. In general, 5,000 or 6,000 large sods may go to the heap, 

 which will thus contain 1,600 cubic feet. The mass must be allowed to heap more 

 than is necessary for wood ; and the process requires to be very carefully attended 

 to, from the extreme combustibility of the charcoal. The quantity of charcoal ob- 

 tained in this mode of carbonisation is from 25 to 30 per cent, of the weight of 

 dry turf. 



For many industrial uses the charcoal so prepared is too light, as, generally 

 speaking, it is only with fuel of considerable density that the most intense heat 

 can be produced, but by coking compressed turf, it has already been shown that 

 the resulting charcoal may attain a density of 1-040, which is far superior to 

 wood-charcoal, and even equal to that of the best coke made from coal. As to 

 zaloriflc effects, turf-charcoal is about the same as coal-coke, and little inferior to 

 wood -charcoal. 



It is peculiarly important, in the preparation of the charcoal from the turf, that the 

 material should be selected as free as possible from earthy impurities, for all such are 

 concentrated in the coke, which may be thereby rendered of little comparative value. 

 Hence, the coke from surface-turf contains less than 10 per cent, of ash, whilst that 

 dense turf of lower strata contains from 20 to 30 per cent. This latter quantity might 

 altogether unfit it for practical purposes. Ansted. 



