1. Dr. Brewster’s Memoirs. 363 
II. Foreten.. 
1. Dr. Brewster’s Memoirs. 
We have received from Dr. Brewster of Edinburgh, the 
following Memoirs, which he had obligingly forwarded to 
us, previously to their publication in Europe. should 
have noticed them in our last number, had not ill health 
prevented, (Ed.) 
t. Description of a monochromatic Lamp, for microscopical 
R. S. E 
absorb the different portions of the prismatic spectrum.— 
2. The influence of heat in modifying this absorbent pow- 
er—and 3, the determination of the question, whether or 
not yellow light has a separate and independent existence 
tm the solar rays. This Dr. B. decides in the affirmative, 
and moreover that the prism is incapable of decomposing 
that part of the spectrum which it occupies. 
2. Additional observations on the connection between the 
Primitive forms of minerals and the number of their axes of 
ouble refraction.—This is a continuation of a former pa- 
per on the same subject. Since the publication of the 
former paper the objections to his principle have been re- 
