278 
is little danger of much aeriform matter flying off. 
If the temperature is higher, the dung should be 
immediately spread abroad. 
When a piece of paper, moistened in muriatic 
acid, held over the steams arising from a dunghill, 
gives dense fumes, it is a certain test, that the de- 
composition is going too far ; for this indicates 
that volatile alkali is disengaged. 
When dung is to be preserved for any time, the 
situation in which it is kept is of importance. It 
should, if possible, be defended from the sun. To 
preserve it under sheds would be of great use ; or 
to make the site of a dunghill on the north side of 
a wall. The floor on which the dung is heaped 
should, if possible, be paved with flat stones ; and 
there should be a little inclination from each side 
towards the centre, in which there should be drains 
connected with a small well, furnished with a pump, 
by which any fluid matter may be collected for the 
use of the land. It too often happens that a dense 
mucilaginous and extractive fluid is suffered to 
drain away from the dunghill, so as to be entirely 
lost to the farm. 
Street and road dung , and the sweepings of houses 
may be all regarded as composite manures; the 
constitution of them is necessarily various, as 
they are derived from a number of different sub- 
stances. These manures are usually applied in a 
proper manner, without being fermented. 
Soot 9 which is principally formed from the com- 
bustion of pit-coal or coal, generally contains like- 
wise substances derived from animal matters. This 
is a very powerful manure. It affords ammoniacal 
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