39 8 PEAT 



feeding fresh fuel to the bottom of the fire instead of to the top, so that as the tar, hydro- 

 carbon vapours and steam distil out from the coal, they have to pass through a mass of 

 incandescent carbon above, which decomposes the complex tar vapours into simple hydro- 

 carbons. These are then completely burnt up on reaching the fresh air supply at the top of 

 the fuel. The fact however that any special form of grate would require the removal of 

 the old type and introduction of the new, has been sufficient to prevent any success in this 

 direction, and what is really needed to make smoke prevention a practical possibility is the 

 introduction of a fuel which could be treated in every way like coal, which would be as 

 easy to ignite, would burn with a cheerful flame, and would in reality commence its combus- 

 tion just at that period when, in a fire, the smoke has ceased and the fire has burnt clear. 



"Coalite" was a fuel which fulfilled these conditions exactly, and consisted of coal car- 

 bonised at 420 C. instead of at 1000 C. ; it was in fact a half-coked coal of uniform com- 

 position, with enough volatile matter left in it to give it the needed properties. For various 

 reasons, unconnected with the nature of the fuel itself, coalite has not so far proved a com- 

 mercial success; but it has convinced everyone who has used it that it is infinitely superior 

 as a fuel to any bituminous coal, and has created such a demand for a smokeless fuel that 

 some imitations, which differ from gas coke only in name, have been able to find a market. 

 The best known of these is "Coalexld," made by mixing a very small proportion of alkaline 

 nitrates with the coal before carbonisation. These evolving small traces of oxygen on their 

 decomposition give small areas of high temperature during destructive distillation, and 

 so give a slight increase in the gas yield. Another is made by cooling the hot coke when it is 

 drawn from the retort by smothering it with a layer of coke breeze, instead of quenching it 

 by water in the usual way, and is known as "Charco." Both these cokes contain about the 

 same amount of volatile matter as ordinary coke made from the same coal. 



Ordinary gas coke is not a popular domestic fuel; it is often over-quenched at the gas- 

 works and sent out too wet, whilst its ignition point, if made at a high temperature, is nearly 

 double that of coal, so that it is difficult to light and gives a dull fire, unless the chimney 

 draught is exceptionally strong. With the introduction of continuous carbonisation in 

 vertical retorts (see under GAS MANUFACTURE) the quality shows distinct improvement 

 in dryness, and it would be easy for the gas manager so to regulate the heat of carbonisation 

 as to leave 3 or 4 per cent of volatile matter in the coke to fit it lor domestic use. 



Peat. The vast area of the recorded peat bogs existing in the world, which in Great 

 Britain alone amounts to 800,000 acres, and the fact that dry peat, especially in the form 

 of briquettes, is a pleasant and efficient form of fuel, have led to many attempts being 

 made to utilise this enormous store of latent energy. So far all attempts to solve the 

 problem have been commercial failures, as the mass of raw peat existing in the bogs 

 contains approximately 90 per cent of its weight of water, most of it so held in a condi- 

 tion of feeble combination that it cannot be pressed out mechanically, whilst if heat 

 is employed to drive it off, as much is needed as remains in the residual solid, and the 

 attempt ends in a loss equivalent to the money expended on labour. 



In countries where coal has been abnormally expensive and the climatic conditions 

 good, cutting and stacking the peat in such a way as to allow air-drying to reduce the 

 moisture to about 50 per cent, and then driving off some more of the remaining moisture 

 by artificial heat and briquetting the product with 10 to 20 per cent of moisture still in 

 it, has yielded small profits, but the enormous area needed for the air-drying, the amount 

 of labour needed to cut the peat, and the fact that it is possible to do so only for a few 

 months in the year, have prevented anything like commercial success, whilst in most 

 countries the humid climate of the peat districts renders such a process impossible. 



In 1906 Dr. M. Ekenberg discovered that peat, consisting as it does of partially 

 decomposed vegetable matter, contains cells which are filled with and coated by a slimy 

 substance, which he called hydrocellulose, and that this jelly-like compound held the 

 water in such a way that mechanical drying of the peat by pressure was not possible, 

 but that when heated to 150-200 C. the slime became "hydrolised " and went into solu- 

 tion, and that the peat so treated could be made to part with its water under hydraulic 

 pressure. Starting from this point the Ekenberg process of " wet carbonisation " was 

 elaborated, and works have been erected on a peat bog near Dumfries, the working of 

 which has been designed to obviate both the climatic and labour difficulties. 



In this process the peat is mixed with sufficient water to render it fluid enough to pump 

 through tubes, and with a dry bog extra water would have to be added ; at Dumfries however 

 the bog is sufficiently wet for the purpose. The peat is dug by an ordinary mechanical digger 

 of the type used in civil engineering operations, mounted on a pontoon which floats in the 



