DOI Seite / Zitierlink:
https://doi.org/10.11588/diglit.19574#0127
C O L f 13
fait it \ and thus is the fame ray alternately reflected and tranf-
liiitted, i. e. the plates correfponding to the odd numbers, r, 2,
3> 5-> 7» &c- wiM reflect the fame rays, that thofe correfponding.
to the even ones, 2, 4, 6, 8, &c. tranfmit.
Hence an homogeneous Colour in a plate is faid to be of the
firft order, if the plate reflect all the rays of that Colour. In a
plate, whofe thinnefs is in a threefold proportion to the firft, it
is faid to be of the fecond order; in another, whofe thinnefs is five
times that of the firft, it is faid to be of the third order, &c.
A Colour of the firft order is the moft vivid of any, and fuc-
ceffively the vividnefs of the Colour increafes, as the quantity of
the order increafes ; the more the thicknefs of the plate is in-
creafed, the more Colours it reflects, and thofe of more different
orders.
In fome plates the Colour will vary as the pofition of the eye
varies; in others it is permanent.
Colours of natural bodies. Bodies only appear of different
Colours, as their furfaces are difpofed to reflect rays of this or
that Colour alone, or of this or that Colour more abundantly
than any other; hence bodies appear of that Colour which ari-
fes from the mixture of the reflected rays.
All naural bodies confift of very thin tranfparent lamellae ;
which, if they be fo difpofed in regard to each other, as that
there happen no reflections or refractions in their interftices, thofe
bodies become pellucid or tranfparent; but, if their intervals be
fo large, and thofe are filled with fuch matter, or fo empty, in
refpect to the denfity of the parts themfelves, as that there hap-
pen a number of reflections and refractions within the body, the
body in that cafe becomes opaque.
The rays, which are not reflected from an opaque body, pe-
netrate into it, and, there fuffering innumerable reflections and
refractions, at length unite themfelves to the particles of the
body itfelf.
Hence an opaque body grows hot the fooner, as it reflects light
lefs copioufly ; whence we underftand the reafon why a white
body, which reflects almoft all the rays that ftrike upon it, heats
much more flowly than a black one, which reflects (carce any.
In order to determine that conftitution of the furface of bodies,
wherein their Colour depends, it muft be obferved, that the
fmalleft corpufcles, or firft particles of which furfaces are made
up, are moft thin and tranfparent, and feparated by a medium of
a different denfity from the particles themfelves.
So that, in the furface of every coloured body, are innume-
rable fmaller thin plates, correfponding to thofe of bubbles;
wherefore, what has been obferved of thofe may be underftood
of thefe.
Vol. I. I Hence
fait it \ and thus is the fame ray alternately reflected and tranf-
liiitted, i. e. the plates correfponding to the odd numbers, r, 2,
3> 5-> 7» &c- wiM reflect the fame rays, that thofe correfponding.
to the even ones, 2, 4, 6, 8, &c. tranfmit.
Hence an homogeneous Colour in a plate is faid to be of the
firft order, if the plate reflect all the rays of that Colour. In a
plate, whofe thinnefs is in a threefold proportion to the firft, it
is faid to be of the fecond order; in another, whofe thinnefs is five
times that of the firft, it is faid to be of the third order, &c.
A Colour of the firft order is the moft vivid of any, and fuc-
ceffively the vividnefs of the Colour increafes, as the quantity of
the order increafes ; the more the thicknefs of the plate is in-
creafed, the more Colours it reflects, and thofe of more different
orders.
In fome plates the Colour will vary as the pofition of the eye
varies; in others it is permanent.
Colours of natural bodies. Bodies only appear of different
Colours, as their furfaces are difpofed to reflect rays of this or
that Colour alone, or of this or that Colour more abundantly
than any other; hence bodies appear of that Colour which ari-
fes from the mixture of the reflected rays.
All naural bodies confift of very thin tranfparent lamellae ;
which, if they be fo difpofed in regard to each other, as that
there happen no reflections or refractions in their interftices, thofe
bodies become pellucid or tranfparent; but, if their intervals be
fo large, and thofe are filled with fuch matter, or fo empty, in
refpect to the denfity of the parts themfelves, as that there hap-
pen a number of reflections and refractions within the body, the
body in that cafe becomes opaque.
The rays, which are not reflected from an opaque body, pe-
netrate into it, and, there fuffering innumerable reflections and
refractions, at length unite themfelves to the particles of the
body itfelf.
Hence an opaque body grows hot the fooner, as it reflects light
lefs copioufly ; whence we underftand the reafon why a white
body, which reflects almoft all the rays that ftrike upon it, heats
much more flowly than a black one, which reflects (carce any.
In order to determine that conftitution of the furface of bodies,
wherein their Colour depends, it muft be obferved, that the
fmalleft corpufcles, or firft particles of which furfaces are made
up, are moft thin and tranfparent, and feparated by a medium of
a different denfity from the particles themfelves.
So that, in the furface of every coloured body, are innume-
rable fmaller thin plates, correfponding to thofe of bubbles;
wherefore, what has been obferved of thofe may be underftood
of thefe.
Vol. I. I Hence