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the charcoal may be previously heated to redness. Charcoal 
is the most unchangeable substance known, it may be kept 
for centuries without change, and is, therefore, not subject to 
decomposition. The only substance which it can yield to 
plants, are some salts which it contains, amongst which is 
silicate of potash ; it is known, however, to possess the power 
of condensing gases within its pores, and particularly carbonic 
acid. And it is by virtue of this power that the roots of plants 
are supplied with Charcoal, with an atmosphere of carbonic 
acid, which is received as quickly as it is abstracted.” 
Liebeg seems to have founded this theory of Charcoal '^con- 
densing gases within its pores,” on its indistructibility. Its 
durable quality, however, is but comparative, and English 
chemists admit its decomposition, to which may be attributed 
its powers which have produced such beneficial effects in the 
hands of the gardener. “ Plants do not, however, attain matu- 
rity under ordinary curcumstances, in charcoal powder, when 
they are moistened with pure distilled water, instead of rain 
or river water. Rain water must therefore contain within it 
one of the essentials of vegetable life ; this is the presence of a 
compound containing nitrogen, the exclusion of w hich entirely 
deprives Charcoal of its influence to vegetation.” The admis- 
sion of this fact presents no incoutrovertable argument in 
support of the theory before alluded to, since rain or river 
water may contain the requisite ingredients to facilitate the 
decomposition of Charcoal. 
The experiments of Lucas, which are set forth by the above- 
mentioned eminent man, were carried on in the Botanical 
Garden of Munich. In the hothouse, powdered Charcoal was 
used instead of tan, in which the pots of plants were plunged; 
the requisite warmth being maintained in it by a hollow space 
beneath, which communicated with the fire. The roots of 
some of the plants having descended through the drain hole of 
the pots, soon afforded evidence of their possession of a new 
stimulus, which seems to have first led to the experimenting, in 
the above garden, with charcoal. It was mixed in various 
proportions; sometimes with an equal quantity of earth, and 
sometimes with only a third part, and in each instance the 
results were highly satisfactory. It was then used alone, instead 
of silver sand, to receive cuttings, and, when thus employed, its 
