Os Light and Colours.
they will proceed at different Distancesfrom the Perpendicular EP to the other
Side
The Refracting Body,
Proportion ofthe Sines.
The
Density.
Res.
Power
Air-——
3201
to
0
0
0,0012
IJ208
Glass of Antimony
17
to
9
5,2800
4864
A Pfeudo-Topaz
23
to
14
4,2700
397 ?
A Selenites -
6l
to
41
2 >Z$ZO
5386
Common Glass
3 -
to
20
2,5800
5436
Crystal of the Rock
25
to
16
2,6500
545 b
Island Crystal --
5
to
3
2,7200
6536
Sal Gemmæ -
17
to
11
2,1430
6477
Alum--
35
to
24
1,714°
657°
Borax--
22
to
15
1,714°
6716
Nitre --
3 °
to
21
1,9000
707 9
Dantzick Vitriol
3°3
to
200
1,7150
755 1
Gil ol Vitriol
12
to
7
1,7000
6124
Rain-Water >
529
to
39 6
1,0000
7854
Gum Arabic -
31
to
21
i, 375 °
8574
Spirit of Wine rectified
100
to
73
0,8060
10121
Camphire -.-
3
to
2
0,9960
12551
Oil Olive -
22
to
15
0,9130
12607
Lintieed Oil-
40
to
2 7
0,0120
12819
Spirit ot ' 1 ‘urpentine
25
to
17
0,8740
1322a
Amber -—-
14
to
9
1,0400
13654
A Diamond-
IOO
to
41
3,4000
1455 b.
PlateXXXVI.•Fig. 7.
25. The Refraction of the Air in this Table is & e 'termined by that of the Atmosphere observed by Ast r °'nomers ; for if Light pass through many refracting S u ^stances, or Mediums, gradually denser and denser,terminated with parallel Surfaces, the Sum of all *•.Refractions will be equal to the single Refraction ^would have suffered in passing immediately out ofstrst Medium into the last; because the immergentwill be parallel to the incident one in everysingJy (by Art. 9.) if they were separated; and th e ’being contiguous can make no Alteration. Hence, *A A be the Medium of Air interceding two differsMedia, as B B of Water, and CC of Glass ; then tb ^emergent Ray ei out of the Water is parallel to the s n ' t