' IMPORTANT TYPES OF PEAT MATERIAL. 31 
plant remains or with water pockets as delimiting layers, the ac- 
cumulation of bog peat may settle to a considerable extent. A change 
in the elevation of the gravity outlet or drainage by pumping may 
later be the only feasible method of relief. It is important, there- 
fore, in designing drainage improvements to anticipate a subsidence 
of 10 to 25 per cent in the original profile of the deposit. Many 
bog peat-land areas are now deteriorating because the drainage 
systems laid out by an earlier generation have not provided for 
this shrinkage or have been allowed to get out of repair. Where 
seepage waters and springs arise along the hills bordering the valley 
or basin, intercepting ditches are extended along the lower edge of 
the high lands and provision is also made for the annual removal 
from the drains of any iron or other compound, sand, silt, or invading 
vegetation. The washing in of mineral impurities should be re- 
stricted to the lateral ditches. Saline constituents when present in 
these types of peat tend to appear and to accumulate at the margins 
as iron pan and bog iron or in the form of irregular patches of con- 
cretions near the ditches or overlying subterranean drainage waters 
and springs. The ground-water supply, springs, and the mineral 
subsoil especially require attention in regions of rock formation 
which contain an excess of soluble salts. 
Only the fibrous and poorly disintegrated surface layers of these 
types are of value as litter and mull if properly dried and shredded 
(Table I). A rapidly growing industry in Europe is using these 
plant remains for manufacturing purposes, and they are greatly 
to be recommended for use in this country. The materials are 
shredded by simple tearing machinery and passed through rotary 
sieves to separate the finer mull from the fibrous material, which 
may be used for bedding live stock, for insulation and packing, in the 
manufacture of special grades of charcoal for metallurgical pur- 
poses, of pulp, pads, fiber, or alcohol (by converting cellulosic com- 
ponents into sugar with diluted sulphuric acid). Shredded peat ma- 
terial from certain species of sphagnum mosses, relatively free from 
inorganic impurities and of uniform composition, has been used as 
surgical dressings for wounds and as pads for patients with dysen- 
tery on account of its high absorbent value. It is in many respects 
a good substitute for medicated cotton. 
There is an increased demand in Europe for sphagnum mull prod- 
ucts, the particles of which are not larger than one-eighth of an inch 
(3 mm.) in diameter, as an ingredient with molasses in stock feed 
for fattening purposes and to prevent disorders. Mull from sphag- 
nums as well as from Hypnum mosses and fibrous sedge peat has 
been employed profitably for packing, as an effective deodorizer and 
disinfectant for use in receptacles holding waste animal matter, and 
