94 
Artificial Manures for Swedes. 
decomposition, carbonic acid and water only. But as all 
cultivated soils contain vegetable remains, which afford a much 
more ready and liberal source for carbonic acid, and as, moreover, 
by far the greater proportion of the carbon in plants is derived 
from the carbonic acid existing in the atmosphere, it is needless 
to make special provisions for the supply of carbonic acid. I 
have admitted for brevity's sake that tarry matters are readily 
decomposed, which, however, is by no means the case, for every 
one knows that tar is extensively employed for preserving timber 
from decay. As far as tar itself is concerned, I am therefore 
inclined to ascribe to it an injurious effect as a fertiliser, for it 
must retard the decomposition of organic remains in the soil or 
in the compost heap to which it is added, and must thus delay 
the necessary preparation to which most organic refuse matters 
must be submitted before they can be assimilated by the growing 
plants. If notwithstanding gas-tar produces a good effect, it is 
only on account of the ammonia contained in ammoniacal liquor 
with whicii it is mechanically mixed. There cannot remain, 
however, a shadow of a doubt, that the ammoniacal liquor is a 
far more powerful and at the same time economical manure, which 
will produce no injurious effects, and just as beneficial effects as 
gas-tar, when properly diluted with water. And as ammoniacal 
liquor is cheaper than gas-tar, and as a fertiliser goes at least ten 
times as far as the tar, tlie utility of knowing on what principle 
the fertilising effects of both refuse manures depend will become 
at once apparent. 
Again, shoddy, a wool-refuse of flock-works, is recommended 
by some as an excellent manure for wheat and corn crops in 
general, whilst otliers condemn it as quite useless. How can 
these differences of opinion be reconciled, when equally good 
men have ascertained practically the value of shoddy, and know 
by experience what it is worth as a manure ? I have seen shoddy 
applied to wheat apparently without the slightest effect, and in 
other cases the effect produced by the same refuse on wheat was 
wonderful. A reference to the analysis of shoddy, and a con- 
sideration of the physical condition of the soils to which and the 
time at which it is applied, readily explain this contrariety of 
opinion. Shoddy often contains 20 to 25 per cent, of oil, which, 
by excluding air and moisture from the interior of the wool-hairs 
which compose this refuse, prevents its decomposition as effec- 
tually as the oil in the sardines a I'huile protects the fishes, or a 
cover of grease the potted meat. At all events, the oil in shoddy 
retaixls its decomposition for a very long time ; and as it natu- 
rally contains hardly any constituent which is of much value as a 
fertilizer, no effect is produced if shoddy is applied to the land 
Avhen the young blade of wheat has already made its appearance. 
