355 
LECTURES ON CHEMISTRY. 
same chemical properties with the common 
mass from which it was taken. There are 
comparatively but few bodies presented to us 
by nature in this isolated state ; among the 
number may be mentioned, as examples, 
gold and the diamond. These, together with 
all other hitherto undecomposed bodies, 
must, in the present state of chemical science, 
be considered as elementary or simple sub- 
stances. Were it practicable to procure and 
exhibit all the elements of bodies in a detach- 
ed form, and to trace the various compounds 
resulting from their union. Chemistry would 
have attained perfection, and no object of 
inquiry Would remain for future experi- 
mentalists. But notwithstanding the great 
acquisition of knowledge derived from the 
discoveries of our contemporaries, they have, 
by no means, enabled us to determine the 
boundaries of the field of science, but merely 
■ to form some conjectural ideas concerning its 
vast extent. 
No correct general knowledge of the nature 
and properties of different substances can be 
acquired without instituting comparisons 
between them, whence we may discover the 
various points of similitude or contrast 
among them, which will enable us to arrange 
them in groups or classes, bearing certain 
relations to each other. 
For the purposes of chemical inquiry, the 
most obviously convenient arrangement of 
bodies is that in which they are classed ac- 
cording to their composition, placing the 
simple bodies first in order, and then the 
compounds arising from the various combi- 
nations of the former. 
According to the ancient philosophers, the 
simple bodies or elementary principles from 
which all the varieties of matter are com- 
posed, were but four, namely. Fire, Air, 
Water, and Earth. This notion, after hav- 
ing for ages formed a part of the creed of 
the learned, has been completely exploded 
by the light of modern science, though it is 
not yet extinct among the vulgar. The al- 
chemical writers of the middle ages added to 
these principles some others, as Salt, Sulphur, 
and Mercury ; to which terms, however, they 
attached ideas very different from those that 
belong to them at present, and into the na- 
ture of which we shall not stop to inquire. 
Some of the alleged elements of the older 
chemists are now known to exist only in ima- 
gination, and others are ascertained to be, 
by no means, simple substances ; thus, Air 
is found to consist of two different elastic 
fluids or gaseous bodies, which may be sepe- 
rated by various processes, and exhibited 
apart from each other. Water, also, has 
been ascertained to be a compound which may 
be analyzed or decomposed, so as to produce 
two distinct kinds of gas, which may be 
separately collected ; and when again mixed 
together in proper proportions, they may be 
made to form water by their union. 
Other bodies, formerly esteemed simple, 
have yielded to the analytical processes of 
modern chemistry ; but there is a certain 
number of substances, which, either in the 
state in which they are presented to us by 
nature, or as they are procured in various 
operations by art, have hitherto resisted all 
attempts at farther decomposition, and 
which, therefore, as before stated, must be 
regarded as simple substances. Their num- 
ber is not very great, amounting to about 
fifty-four, and it is not unlikely that the future 
researches of chemists may demonstrate 
some of these bodies to be compounds ; at 
the same time, it is probable that additions 
may be made to the class of elementary sub- 
stances in consequence of future discoveries, 
several of those now admitted into this class 
having become known to us but very recently. 
Some of these elementary bodies are widely 
and abundantly dispersed thi’oughout the 
three kingdoms of nature, either alone or in 
a state of composition, while others appear to 
be of very rare occurrence, or, at least, they 
have hitherto been met with only in small 
quantities and in a few situations. The 
whole of the elementary substances may be 
arranged in two divisions : the first compre- 
hending those which are not of a metallic 
nature, the entire number of which now known 
amounts to only thirteen ; the remaining 
forty-one elementary bodies are all regarded 
as metals, though some of them exhibit pro- 
perties differing considerably from those 
which characterize gold, silver, mercury, lead, 
iron, and other bodies, to which the desig- 
nation of metals was originally applied. 
(To he Continued.) 
ELECTRICAL THEORY OF THE 
UNIVERSE. BY Mr. THOMAS 
S. MACKINTOSH. 
Continued from page 225. 
Development of the Theory of the Solar 
System. 
1. Centre of Positive Electricity. — 
The body of the sun has a powerful affinity for 
electricity, and is intensely charged with 
electric fluid ; and is surrounded with an at- 
mospheie of electricity extending to the ut- 
most limits of the planetary systern, decreas- 
ing in density in a certain unknown ratio 
with its distance from the sun. The sudden 
appearance and disappearance of spots on the 
sun’s disc affords proof, even to demonstra- 
tion, that the elementary matter of the sun is, 
at intervals at least, in a state of violent 
commotion ; and when we consider that some 
of these spots are much larger than the earth, 
ho'v vast must be the effort to cause them to ap- 
pear and to disappear in so short a space of 
time as they have hi'en known to do 1 There 
is no known agent in nature capable of pro- 
ducing such vast results except electricity; 
and this consideration alone almost forces the 
conclusion upon us, that the sun is an im- 
mense spherical conductor, highly charged 
with electric fluid. “ The light obtained by 
voltaic electiicity exceeds in intensity any 
other that art can produce ; itisso dazzling 
as to fatigue the eye even by a momentary 
impression; it is a light which so nearly 
emulates the sun’s rays, as to be applicable 
