of these bodies, and by a masterly train of experiments, 
simple yet conclusive, he demonstrated that they are 
metals ; that they have every genes ie is deemed 
essential to characterise this class of substances, and 
that the alkalies are oxides of these metals. The theory 
‘of the decomposition of the alkalies, by means of the 
galvanic apparatus, is sufficiently obvious, and follows 
as the direct consequence of the facts that had been 
viously established. In all the decompositions that 
Fad been effected by the electrical influence, combus- 
tible substances were developed at the negative wire, 
while oxygen was produced or evolved at the positive 
termination, That this was the case with the ies, 
was not only rendered probable by the result of the 
, but was afterwards proved by subsequent ex- 
orkerse «© When solid or soda, in its con- 
ucting state, was included in glass tubes, furnished 
with electrified platina wires, the new substances were 
generated at the negative surfaces ; the gas given out 
at the other surface, proved by the most delicate exa- 
“mination, to be pure oxygen ; and unless an excess of 
water was present, no gas was evolved from the nega- 
eonpeie Th apelin 
romposi- e iments 
lon of the of those by wate 
¥ converted into potash, by exposure to the air, and it 
was found that this depended upon the oxygenous part 
of it. When the globules were placed in contact with 
oxygen, they combined with it, and were covered with 
‘an alkaline crust. Sir H. Davy observes very justly, 
“ that in these facts there is the same evidence for the 
decomposition of potash and soda into oxygen and two 
peculiar substances, as there is for the decomposition of 
sulphuric and phosphoric acids and the metallic oxides, 
into’ oxygen and their respective combustible bases.” 
The two components of the alkalies obey the general 
law which was laid down in the former paper ; the me- 
tallic or combustible base is attracted by the negative 
extremity of the apparatus, and perhaps repelled by the 
positive; while the oxygen, which reduces it to the state 
of an oxide, follows the contrary order. In the recom- 
position of the alkalies, the substances exert their na- 
tural affinities; according to circumstances, either simple 
oxidation is produced, or a more rapid combination, at- 
tended with the extrication of heat and light. 
_ Sir H. Davy next proceeded, in an elaborate train of 
experiments, to ascertain the physical properties of 
these metals, to which he gave Galosraks of potassium 
and sodium, and their chemical relations to other bodies. 
He examined their fusibility, the power which they 
possess of conducting electricity and caloric, and their 
specific gravity. He afterw observed their action 
_ on water, the acids, sulphur, phosphorus, the metals, 
oils, and metallic oxides. It is scarcely necessary to 
remark, that the examination was conducted with the 
address and dexterity which characterizes all the opera- 
tions of this distinguished experimentalist. A minute 
detail of etnies would be foreign to the object 
of this article, and strictly belongs to the science of 
'; galvanism being no farther connected with 
ies, than as the instrument by which they are 
produced. On this account it will not fall under. our 
province to notice the discussions, which ensued re- 
specting the nature of these new metals; for although 
it was generally admitted that the substances were the 
bases of the fixed alkalies, and were metallic, yet there 
were some circumstances in the mode of ‘their forma- 
tion, which led to the supposition, that they were a 
) 
tre confirmed the results 
he new metallic bodies were 
chemis 
these 
GALVANISM. 
91 
compound of a métal avid hydrogen; but this opinion History. 
is now abandoned, Sy= 
The analogy which exists between, the properties of Attempts 
the fixed and the volatile alkalies, led Sir H. Davy to to decom- 
apply his powerful means of decomposition to ammonia, P0*€,2™- 
he analogy of properties, however, which causes them '“°™ 
to be Ricca in e same.class of bodies, seemed to be 
counteracted by the experiments of Berthollet, who, as 
is well known, had resolved. this latter substance en- 
tirely into hydrogen and azote. Accordingly the me- 
tallic nature of ammonia has. not yet been proved, and 
although Sir H. Davy, in his earlier experiments, con- 
ceived that he had procured oxygen. from it, and. Ber- 
zelius obtained a species of oes ite by exposing it.in 
contact with mercury to the galvanic influence, yet 
subsequent experiments by Henry, and Gay-Lussac and 
Thenard, appear to explain these appearances on other 
principles, and to restore the original conclusion, that 
ammonia is a compound.of azote and hydrogen alone, 
See Phil. Trans. for 1808, p. 1. j 
.. Sir H. Davy next turned his. attention to-the earths, Decompo-- 
He found them more. difficult to decompose than the sition of 
alkalies, and many arrangements were employed with. ® “"'"* 
out success. The object was, however, at length, toa 
certain degree, accomplished by mixing the earth with 
a metallic oxide, or placing this .in. contact, with a 
globule of mercury negatively electrified, when an 
amalgam was-formed, consisting of the mercury and 
the metal of the earth employed. In this. way it ap- 
peared, that a metallic basis had certainly been. obtain- 
ed from the four alkaline, earths, to which the names 
of barium, calcium, strontium, and magnium, were re- 
spectively applied. The remaining earths, silex, alu- 
mine, zircon, and glucine, were still more refractory, 
probably in consequence of their more pymecal affini- 
ty for oxygen... No decomposition could be effected b 
_the same means which bad ban found successful. with 
the alkaline earths ; but. it was at Jengsh partially ac- 
complished, by keeping the earth in. fusion with pot- 
ash, inducing upon it positive electricity, and touching 
it with a negative wire. In this case an amalgam was 
produced, which probably consisted of the metal of the 
earth employed and potassium, See Phil..Z'rans. for 
1808, p. 833. 
The brilliant discoyeries of Sir H, Davy, and still Confirma- 
more the new and powerful agent which he had intro- tion of 
duced into chemistry, could not fail.to engage the at- D#vy’s ex- 
tention of all those who were interested in the progress P°"°"'* 
of the science. Among these,,Gay-Lussac and The- 
nard in France, and Berzelius in Sweden, immediately 
commenced their operations in the application of gal- 
vanic-electricity to the decomposition of bodies, made 
many important experiments, and brought to light 
many new facts. The general result was, to afford an 
ample confirmation of the statements of our illustrious 
countryman in their most, important parts, although in 
some particulars they regarded the subject in a diffe- 
rent point of view, both as to the mode of accounting 
for the effects, and the consequences which they dedu- 
ced from them. These discussions, as well as the many 
new.and interesting experiments connected with them, 
which have. completely. changed the aspect of many 
branches. of chemistry, and haye enlarged our know- 
ledge of the nature of bodies far beyond its former li- 
mits, it does not belong to our department to detail. 
It will be proper, however, to. lay before our readers 
some of the observations that were made by Gay-Lus- 
sac and Thenard, on what strictly belongs to galvan- 
