ON CHEMISTRY. 
43 
considerations of the deepest interest in the science of gardening. 
It has generally been believed, that the soluble parts of manures are 
taken up by the vegetable organs; it has also been maintained that, 
the carbon of the manure is converted into carbonic acid, and that 
this acid, in a state of solution in water, is absorbed by the roots. 
Of late years we have heard much of Humin, humic acid, neutral 
humates, &c. which substances have been pronounced to be food 
of plants; and they are said to be found abundantly in the soft, ad¬ 
hesive mass of spit dung. I have stated my views upon the subject of 
Humin, in several articles which have appeared in the Quarterly 
Journal of Agriculture, and British Farmers' Magazine ; and here, 
in a few words, I avow my decided opinion that, in the announced 
discoveries, we have obtained nothing, but merely a set of new names 
or terms, for that reduced nutritive substance, which every farmer and 
gardener has familiarly known from time immemorial, viz. the labo- 
rated, blackened mass of the dunghill, Humin, or reduced manure, 
is a compound of oxygen, hydrogen, carbon, chiefly; it may also 
contain azot, and some salts and earths. It is the product of decom¬ 
position, effected, when vegetable and animal matters are fully ex¬ 
posed in a heap, to the agency of solar light and atmospheric air; 
and it varies in its components, in as far as it is formed of substances 
whose elements may vary. Decomposition, effected by fermentation, 
is a process of slow combustion, and its results may be traced by ex¬ 
posing the substances which would be placed in the dung heap to the 
action of direct fire. If these be distilled in glass or stone vessels, 
over a charcoal fire, furnished with recipient vessels for the proper 
retention of the products, a pungent and oily liquor will be obtained, 
which has a very disagreeable burnt odour, evincing traces of am¬ 
monia. Gaseous fluids are also abundantly given forth, abounding 
with carbonic acid, and carburetted hydrogen. These distilled pro¬ 
ducts prove, beyond the shadow of a doubt, 1st the presence of Oxy¬ 
gen and carbon to form the Carbonic acid ; —2nd, that of hydrogen 
and carbon to form Carburetted hydrogen gas, and the oily fleeting par¬ 
ticles ; 3rd, that of hydrogen and azot to form the ammonia ; and 4th, 
that of oxygen, hydrogen and carbon, to form an acid liquor, which, 
very frequently, is deposited in the first receiver. If the process be 
pressed till the matters in the retort cease to yield gases, and become 
red hot, the analysis of the blackened mass, will detect very compound 
products. Who, that is uninitiated, would suspect that in a portion 
of Cow manure, dried, and distilled, and then heated to redness, 
would be found not only free charcoal, some salts; as sulphat of pot- 
assa—Carbonate of potassa, (pearl ash) sulphat and muriate of lime, 
e 3 
