968 
(763.) 
trite Electro-chemical Theory—Decomposition of the 
chemical Alealies.—In 1804 Berzelius had published, in con- 
theory— junction with Hisinger, a paper on Electro-chemical 
Berzelius, Decompositions, in which he insisted on the general 
rn ye fact, that alcalies, earths, and combustible bodies seem 
first Bake- to be attracted to the negative pole, and oxygen and 
rian lec- acids to the positive. He also showed thatthe sub- 
—_ division of bodies thus obtained was only a relative 
not an absolute one; for the same body may act 
as a base to a second, and as an acid to a third. 
But we must observe that results almost similar 
were contained in the early papers of Davy, and 
that Berzelius did not carry out his own principle 
so far as to lead to any striking discovery between 
1803 (when his experiments were made) and 1806 
(the date of Davy’s first Bakerian lecture), during 
which time the science of Galvanism or Voltaism 
‘made little real progress. The numerous experi- 
menters engaged with it were baffled by the anoma- 
lous chemical results obtained, and by the appearance 
of decompositions under circumstances wholly unex- 
pected, such as appeared to threaten the existence of 
some of the best established chemical truths. The 
chemical theory of the pile, at first so plausible, pre- 
sented new difficulties, and Berzelius having for a 
while defended it, returned to the simple contact 
theory of Volta. It was then that Davy seriously 
addressed himself to the subject, resolved to trace 
to their source every chemical anomaly; and this 
he effected in a masterly manner in his Bakerian lec- 
ture read before the Royal Society in 1806. In it he 
traces the unaccountable results of his predecessors to 
impurities in the materials used by them, or to those of 
the vessels in which the decompositions were made; 
and he brings into a far distincter light than his pre- 
decessors had done, the power of the galvanic circuit 
to suspend or reverse the action of even powerful 
chemical affinity ; “different bodies naturally pos- 
sessed of chemical affinities appearing incapable of 
combining or of remaining in combination when placed 
in a state of electricity different from their natural 
order.” We here see the fundamental doctrine of 
the electro-chemical theory, that all bodies possess 
a place in the great scale of natural electrical rela- 
tions to one another; that chemical reactions are 
intimately connected with this electric state, and are 
suspended or reversed by its alteration. 
Davvs eee In the interpretation of those striking experi- 
gacious ments, in which he caused acids to pass to the posi- 
inductions tive pole of the battery through the midst of alcaline 
respecting solutions, and the converse, we find so close an ap- 
wae proach to the theory of polar decomposition as enfor- 
ced by the discoveries and reasoning of Mr Faraday, 
that it seems impossible to deny to Davy the merit 
of having first perceived these curious relations. 
** Tt is very natural,” he says, “ to suppose that the 
repellant and attractive energies are communicated 
(764.) 
MATHEMATICAL AND PHYSICAL SCIENCE. 
[Diss. VI. 
from one particle to another particle of the same kind 
so as to establish a conducting chain in the fluid, 
and that the locomotion takes place in consequence ;” 
and presently adds, «‘ there may possibly be a succes- 
sion of decompositions and recompositions through- 
out the fluid” (p. 29)! He likewise shows (p. 21) 
that the decomposing power does not reside in the 
wire or pole, but may be extended indefinitively 
through a fluid medium capable of conducting elec- 
tricity, Mr Faraday’s experiments, which led him to 
discard the term pole, lead to the same conclusion, 
and are of the same character, A few pages further 
on in this same Bakerian lecture, Davy observes (p. 
42), that “ allowing that combination depends on a 
balance of the natural electrical energies of bodies, 
it is easy to conceive: that a measure may be found 
of the artificial energies as to intensity and quantity 
capable of destroying this equilibrium; and such a 
measure would enable us to make a scale of electrical 
powers corresponding to degrees of affinity.” Here 
we see the acute presentiment of the beautiful disco- 
very of the definiteness of electrical decompositions; 
as in the concluding portion of the same remarkable 
paper we find a clear anticipation of natural elec- 
trical currents to be discovered in mineral, and espe- 
cially metalliferous deposits, since established by 
Mr R. W. Fox, and of* the agency of feeble electric 
energies, long continued, in effecting geological chan- 
ges, and in producing insoluble combinations of earths 
and metals, so ingeniously confirmed by the beautiful 
and direct experiments of Becquerel. 
The sequel to this remarkable paper, read to the 765.) 
Royal Society in November 1807, contained the splen- Second 
did application of the principle and methods which it ee 
described, to the decomposition of the alcalies and to eomposi- 
the discovery of their singular bases,—substances po- tion of the 
sessing the lustre and malleability of metals, yet so *calies. 
light as to float upon water, and having the extraordi- 
nary property of becoming inflamed in contact with 
ice. Potassium was discovered in the Laboratory of 
the Royal Institution on the 6th October 1807, and 
sodium a few days later, The battery used con- 
tained 250 pairs of plates of 6 and 4 inches square. 
Such success was fitted to charm a disposition like 
that of Davy, and more than reward him for all his 
toils. To have discovered two new bodies, and 
opened an entirely new field of wide chemical re- 
search, would itself have been enough. But the 
extraordinary properties of the new bases were such 
as seemed to correspond to the lively imagination 
of the Chemist who produced them, and to transport 
him to an Aladdin’s palace more brilliant than even 
his fertile imagination had ever conceived. Yet it is 
pleasing to remember that these popular discoveries Receives a 
followed, at the interval of a year, the patient and peg 
able researches which led him to them, and which tute of 
had already been rewarded, at a period of the bitter- France. 
1 Of the Bakerian Lecture, in his collected Works. 
