12 
GARDENING AS A SCIENCE. 
We know nothing of the Vital principle — it may be a Fiat — partaking of the 
nature of the breath of life ; — it may be sentient, conferring on a plant, however f 
low in its degree, some trace of feeling and volition ; or it may be electro-magnetic, j 
acting altogether through the instrumentality of attraction and conduction. We 
lean to this last opinion, because we perceive in every act of nutrition some pheno- 
mena of chemical decomposition ; but setting aside these considerations, it is quite 
certain, and will be self-evident to the philosopher who inquires aright, that every 
part of a tree or plant, and all its productions, when deprived of life, are subject to 
chemical laws, and can be explained by them and them alone. 
To commence with the wood (lignum ), whether of the trunk or main root : 
we have nothing more to do than to examine the white ashes which are found in 
a bread-oven heated by billets. A little diluted muriatic acid added to a drachm 
weight, till the hissing or effervescence cease, will exhibit a clear liquid, with a 
quantity of grayish sediment at the bottom. The effervescence will show that 
carbonated alkali or earth existed in the ashes, which the clear liquid now 
holds in solution. If, into this, a few drops of prussiate of potash be let fall, a 
precipitate of Prussian blue will prove the presence of iron, which, being 
separated by a paper filtre, will permit the application of carbonate of potassa 
(salt of tartar) dissolved in rain water, to the remaining fluid. This will cause 
the copious deposition of a white substance, which, in almost every instance, is 
chalk. 
Thus, in most kinds of wood, a quantity of chalk, some alkali, iron, and 
certain insoluble matters are found to exist, and are traceable by the two re-agents 
above named. These substances, as they are not destructible by fire, are termed 
the inorganic constituents of plants. The organic , or organized constituents, are 
those which are resolvable into the elements of water and air, combined in multi- 
farious conditions with a volume of carbon, the base of fibrous, woody matter. 
These combinations are the origin of all the vegetable products — acids, starch, 
gum, sugar, oils and resins. They are decomposable by fire, which also 
disposes their carbon to combine with the nascent elements of the other pro- 
ducts, and to pass off in the state of carburetted hydrogen, carbonic acid, and 
other gases. 
The same volume of wood, which, burnt in the presence of atmospheric air, 
produces the white or gray ashes above alluded to, would, in the close retorts of the 
laboratory, yield, first — a quantity of impure pyroligneous acetic acid , and secondly 
• — a bulk of black charcoal, equal to that of the wood, and exhibiting the figure 
and position of its fibrous and horizontal tissues. 
The leaves , the twigs, and the minute roots yield, with some modifications, 
pretty nearly the same results ; and thus we arrive at two important discoveries. 
First — that by the application of proper tests, we discover the elements into which 
all vegetable matters, organic and inorganic, can be resolved. Secondly — we learn 
that by analysis of the insoluble ashes, left after the combustion of plants of all 
