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XIX. On new Properties of light exhibited in the optical Phe- 
nomena of Mother of Pearl, and other Bodies to zvhich the 
superficial structure of that Substance can be communicated. By 
David Brewster, LL.D. F. R. S. Edin. and F.S.A. Edin. 
In a Letter addressed to the Bight Hon. Sir Joseph Banks, 
Bart. K. B. P. R. S. 
Read April 28, 181^. 
In the prosecution of my inquiries into the modifications 
impressed upon light by the various bodies of the animal, the 
vegetable, and the mineral kingdom, I have had the good 
fortune to discover several new properties of light, and to 
establish the laws which regulate the most remarkable of the 
phenomena. A few of these results have already been laid 
before the Royal Society ; and from the reception which they 
have experienced, I have taken the liberty of addressing to you 
the following paper containing a series of new facts, remark- 
able for their extreme singularity, and their opposition to 
almost all our notions of the action of bodies upon the luminous 
rays. The extraordinary character which these experiments 
at first assumed, induced me to think that I had overlooked 
some source of deception ; and it was not till I had performed 
them under every variety of circumstances, and till they had 
been repeated, and viewed in the same light by several of my 
friends, that I prevailed upon myself to bring them under your 
notice. 
The splendid exhibition of colours which distinguishes 
MDCCCXIV. 3 F 
