OF GARDENING AS A SCIENCE 
251 
the above ; nor one which the candid scholar could less desire or attempt to 
impugn : it is that position to which allusion was made in the early lines of this 
article, and that we hope to substantiate by one easy experiment. If to the cushion 
or rubber of an electrical machine, a Leyden jar be attached by a small hook, in 
lieu of the cliain which usually is suspended from it, and if another jar of the same 
capacity be applied to the extremity of the prime conductor, both jars will become 
equally charged by any given number of turns of the plate or cylinder. But 
according to the plus and minus theory, the jar at the cushion ought thus to 
become partially or fully exhausted ; whereas, both are equally charged, but 
with electricity of opposite character, for the knob of one jar will attract that which 
the other repels ; and thus if both jars be placed upon a chain or strip of metal, so 
as to connect their outer surfaces at bottom, the knobs being a foot or more distant, 
a jointed discharger applied to those knobs at the same moment, will cause the 
electricities of the two jars to unite with a report, strong in proportion to the 
charges of each jar. The experiment is conclusive, its phenomena cannot be 
denied or questioned. 
Comhustion^ whether visible and energetic, or concealed and slowly progressive, 
as in the heating of a hayrick, and decomposing hotbed, are manifestly within the 
range of horticultural science ; and here again we observe a masterly passage at 
page 68. The reader must be, however, prepared to recognise in combustion the 
strong attractive energy of the two elements of water, of electrised oxygen and 
hydrogen, or in other words, the combination of their bases with electricity. 
" Combustion is the result of chemical action arising from the electrical principle. 
Flame is nothing more than the burning of two gaseous bodies in the act of com- 
bining under electrical influence ; and as solids burn by showing only a red or a white 
heat, according to the temperature which produces combustion, that is to say de- 
composition, attended by light as well as heat ; gases, or rather gaseous explosive 
mixtures, whose elements meet gradually, burn by showing only what we call Jlame^ 
because the gases themselves are invisible. The only element of combustion (or 
archeal element) that animals can respire and not die, is oxygen, which, in a diluted 
state, the diluent being nitrogen, constitutes the vital air of living and breathing 
creatures. It follows, therefore, that the agent or pabulum of all our domestic fires 
and lights is oxygen. All these fires and lights arise from the combustion caused 
by a mixture of oxygen and hydrogen in their effort, under electrical agency, to 
unite and form water. Thus the flame from coal, wood, paper, rag, oil, fat, wax, 
and candles of all descriptions, is nothing more than the formation of water. But 
all such fuel contains, besides hydrogen, the element carbon, which is of great use 
in giving light ; for though the combustion of hydrogen, in the oxygen of the 
air gives out great heat, it affords very little light, and, tlierefore, it is to the 
vapour of carbon combined with it that we owe the bright flame of a coal or 
wood fire, or of a candle. Thus, simultaneously with the water, carbonic acid is 
formed." 
