20 
Dr. Brewster on the absorption of polarised light 
Nitrate of copper 
Chromate of lead 
Staurotide 
Augite 
Anhydrite 
Axinite 
Diallage 
Sulphur 
Axis of prism in the 
plane of primitive 
polarisation. 
Bluish white 
Orange 
Brownish red 
Blood red 
Bright pink 
Reddish white 
Brownish white 
Yellow 
Sulphateof strontites Blue 
cobalt Pink 
Olivine Brown 
Axis of prism perpendicular 
to the plane of primitive 
polarisation. 
Blue 
Blood red 
Yellowish white 
Bright green 
Pale yellow 
Yellowish white 
White 
Deeper yellow 
Bluish white 
Brick red 
Brownish white 
In the last eight crystals of the preceding table the tints 
are not given in relation to any fixed line. 
The following table contains the characters of m and n in 
crystals, the number of whose axes I have not yet deter- 
mined. 
Phosphate of iron Fine blue* 
Actinolite Green 
Precious opal Yellow 
Serpentine Dark green 
Asbestos Greenish 
Bluecarb. of copper Violet blue 
Octohedrite Whitish brown 
Several of the preceding crystals which have a laminated 
structure, such as mica, epidote,&c. or such as have an imper- 
fect transpareacy from a defective aggregation of their elemen- 
tary crystals, frequently exhibit their absorptive qualities, and 
Bluish white 
Greenish white 
Lighter yellow 
Lighter green 
Yellowish 
Greenish blue 
Yellowish brown 
* When the axis of the prism was in the plane of primitive polarisation. 
