7 It DIGGING AND PREPARATION OF PEAT. 



liarnffiii, in mt-tallur^'y, Sec, and should fulfil the following: 

 conditions : — 



Density. — The turves must not merely be dense superficially, 

 nor so dense at the surface that the air cannot reach their 

 interior, but be uniformly dense throughout. 



Compactness. — The turves must be compact enough not only 

 to retain their shape during transport, but also while being 

 burned. 



High combustible power. — During manufacture, the most com- 

 bustible parts of the peat must be carefully preserved, especially 

 the amorphous peat. 



Drjmess. — The peat must be thoroughly dried, not only super- 

 ficially, but also internally ; it should, as far as possible, lose its 

 great hygroscopicity and not swell considerably when exposed 

 to damp and thus become unserviceable. 



Quantity. — The manufacture must be so conducted as to 

 yield large quantities of material and be independent of the 

 weather. 



The cost of production, including that of supervision, must 

 be sutiiciently low to allow the material to compete with other 

 locally used fuels. 



The following methods have been undertaken to secure the 

 above conditions : — contraction, dry pressure, wet pressure and 

 destruction of structure with or without pressure. 



All these methods are, however, too costly to repay the 

 expense unless the price of fuel is as high as during the forties 

 of this century. Several of these methods have fallen into 

 disuse, whilst others have been adopted. The former will, there- 

 fore, only be shortly considered, more attention being given to 

 those still in vogue. 



(a) Contraction. — Chnlleton at Paris, and Hay at Neuchatel 

 adopted the following method of increasing the density of peat. 

 The turves were cut from a bog, brought to the factory and then 

 cut to pieces by a system of rollers with blades fixed on them ; 

 the material was then treated with running water so as to form 

 a thin pulp, which runs over fine sieves in order to remove all 

 coarse fibres. This fine pulp is then led in canals to a trench 

 one to two feet deep, the bottom of which is covered with reeds 

 or rushes. In this trench the pulp sets firmly, the water drain- 



