IMPORTANT TYPES OF PEAT MATERIAL. 25 
debris undergoing weathering and disintegration. As surface ma- 
terial this blackish fine-grained component is almost impervious to 
water, probably due to the absorption of air. Windbreaks, pref- 
erably of alder, maple, and willow, are necessary to prevent injury 
from dust storms to seedling crops, but a rotation which includes 
broad-leafed crops or plants with a fibrous root system to hold the 
fine-grained debris would be more advantageous and would aid in 
maintaining a favorable water content at the surface of the soil if 
irrigation measures are not feasible. 
The first crop to be planted deserves, therefore, careful considera- 
tion, as it materially affects the disintegration of the plant remains. 
On poorly disintegrated, fibrous phases of these peat types, potatoes 
and corn are considered desirable. Where droughts are of rare 
occurrence not much trouble has been experienced in keeping the 
ground water too low to injure crops of value in intensive modes of 
farming. Ferruginous peat material of these types would, however, 
prove more profitable if under cultivation for hay and pasture. 
The value of these types for industrial purposes is dependent on 
several factors, most important of which are the degree of disinte- 
gration, the ash content, and the impurities. The blackish, com- 
pact, well-decomposed phases with less than 20 per cent of ash 
produce less soot or ether and alcohol soluble and pitchy substances 
than the types of peat which contain the resinous and waxy bodies 
(see Table I). They are therefore considered preferable for the 
manufacture of power gas in gas producers where by-products are 
objectionable and their recovery is not contemplated. As machine 
peat, thoroughly ground, pulped, and air-dried, they yield a fuel 
of good quality, generally near 3,500 calories; they are clean to 
handle, give a relatively intense heat, and are well adapted for 
smaller manufacturing or farming communities and for domestic 
uses. The brick-shaped blocks of machine peat that are allowed to 
air-dry slowly contract into a dense mass covered by a gelatin- 
like outer layer which is reported to be a hyclrocellulose rather than 
a resinous substance; it renders the machine-made product almost 
impervious to water, compact, and more resistant to breakage. 
The coarser textured, partly fibrous phases of peat appear to be 
preferable for composting and as a filler for tankage or a base for 
compounding with fine-ground mineral fertilizers. After excava- 
tion the moist peat material should be piled and stored in mounds 
20 or 30 feet high and kept under cover if possible for at least six 
to eight months. During that time the plant remains shrink con- 
siderably in volume and undergo a slow internal heating, granula- 
tion, and carbonizing process, which may be aided artificially by 
means of pipes heated with " exhaust " steam. The material has been 
