658 
IMPORTANT FACTS BY EXLEY. 
2. That there is a difference in atoms, 
arising from a difference in their absolute 
forces, or in the radii of their spheres of repul- 
sion, or in both these respects. 
The theories of Newton and Boscovich 
agree perfectly with this, as far as regards 
the attraction in the first principle : after 
that Newton and Boscovich go together in 
conceiving a series of alternate spheres of at- 
traction and repulsion governed by unknown 
laws, but, as regards change of direction, the 
forces graduate into each other. Boscovich 
reaches the centre with a sphere of repulsion 
which varies inversely as the simple distance, 
making the force at the centre infinite ; while 
Newton closes with a solid nucleus, wjuch is 
only an infinite force long before we reach the 
centre. I'he new theory rejects all these 
hypothetical, unsubstantiated forces, and their 
feigned alteration ; and, with the utmost pos- 
sible degree of simplicity, admits of but one 
sphere of repulsion, in which, without inter- 
ruption, the law of gravitation in the attractive 
sphere is invariably continued down to the 
centre itself, where it terminates with the 
infinite force of Boscovich lepeated an infi- 
nite number of times. The direction chang- 
es to the opposite one, per saltum, at the 
surface of tlie sphere of repulsion: and why 
not ? It is quite as easy and more natural to 
conceive that it thus changes at once, tiian 
that it is always changing continuously back- 
ward and forward ; but, vvliich is a matter of 
great moment, the continuity of the quantity 
and of the law of force remains unbroken, 
preserving the delightful harmony of nature. 
The inductive philosophy requires and de- 
mands this continuity in the law ; unless the 
contrary could be shown in any instance, we 
have as much right to say that the law of 
gravitation does not exist in the infinity of 
places where no observations have been made, 
as to say it does not exist in the sphere of 
repulsion, that important space in which clie- 
mistry and its connate sciences produce all 
their phenomena. 
Thus since the 1st principle as to attraction 
has long been established completely, by in- 
duction, and beyond the power of contro- 
versy, and since we know from facts that a 
central repulsion exists, the same induction 
obliges us to admit the same force in the sphere 
of repulsion, especially as not a single instance 
of repulsion acting according to any other 
law can be shewn to exist, as belonging to 
any atom of matter. 
The 2nd principle is perfectly simple and 
natural, and is established by means of the 
first principle and induction from facts ; for 
it is known that atoms do differ from each 
other, and the difference stated is in complete 
unison with the first principle, and quite suffi- 
cient to furnish all the variety of atoms yet 
observed, and an infinitely greater variety. 
The material will of course be allowed, and 
we readily admit that the Creator originally 
brought into existence, according to number, 
weight, and measure, a quantity of every sort 
of atoms requisite for the purposes of his grand 
design in the structure of the universe. 
Every variety of atoms may, according to 
th« theory, be assumed ; but to find what 
sorts really exist, phenomena should direct 
the assumptions. 
In my “ New Theory of Physics,’’ it was 
stated that nature presents two classes of 
atoms; the one comprehending the element- 
ary substances most generally known, such 
as oxygen, hydrogen, carbon, &c., which, 
adhering with great tenacity, may (till a bet- 
ter name be found) be termed tenucions 
atoms. 'J'he other included such matter or 
atoms as manifest their existence by motions 
and actions, under a form which has been, 
denominated ethereal, and hence they may 
be called ethereal atoms; to this class was 
assigned the electric fluid, caloric, and light. 
In the same work the atoms of electric fluid 
were considered as having a much greater 
absolute force, than those of caloric and light ; 
and this has been abundantly confirmed by 
subsequent observations, entitling the electric 
atoms to the rank of an intermediate class,. 
Hence, vve have three classes of atoms, viz., 
tenacious, electiic, and ethereal atoms. Of 
the 1st and 3id classes there are many sorts, 
but probably only one sort of electric atoms ; 
this division and arrangement will at least 
serve our present purpose. 
The distinction of the classes is founded in 
a very great difference of the absolute force; 
that of the sorts in a moderate difference: 
thus, if the absolute force of an atom of oxy- 
gen be l6, and that of hydrogen 1, they will 
be two sorts of tenacious atoms; an electric 
atom must be considered very much less in 
absolute force than that of either of the 
former, and the several atoms of light and 
caloric perhaps many millions of times less 
than that of an electric atom. 
In this paper the atomic w'eight of oxygen 
is 16, that of hydrogen being i, as the unit 
of comparison. Itappears to me exceedingly 
unfortunate that the British chemists have 
adopted 8 instead of l6 ; they tell us, which 
shews a want of confidence in their own 
arguments, that it is of no great consequence 
which of these opinions be adopted. This is 
indeed true as it regards many experimental 
determinations, but in theory it is exceedingly 
important. Is it of no consequence to know 
whether a compound contain in each particle 
2, 3, 4, &c., atoms ? If oxygen be 8, a par- 
ticle or atom of ether contains lO simple 
atoms, but, if oxygen be l6, it contains 15 
atoms : would not such a difference alter all 
or most of its properties? A question so 
deeply scientific ought not to be treated with 
indifference. 
I have not seen one argument in favour of 
8 which has any great point or weight : in 
favour of 16 only one has met my notice 
which is a good one : it is this; the simple 
gases hydrogen, nitrogen, and chlorine, con- 
tain an equal number of atoms in equal 
volumes, and oxygen is as much entitled to 
the character of a simple gas as any of them t 
hence, it is reasonable to conclude it is not 
an exception to the rule, but this would require 
16 for its atomic weight. 
