OEE 
LONDON, EDINBURGH anv DUBLIN 
PHILOSOPHICAL MAGAZINE 
AND 
JOURNAL OF SCIENCE. 
[THIRD SERIES.] 
APRIL 1843. 
XL. On Apparatus for the circular Polarization of Light in 
Liquids. By the Rev. Baven Powe t, M.A, F.R.S., &c., 
Savilian Professor of Geometry, Oxford*. 
‘THE subject of circular polarization developed in light in 
passing through certain substances, especially liquids, is 
one which has at the present day attracted considerable atten- 
tion, not merely among those who study the properties of 
light as such, but also among chemists, as supplying a test of the 
existence of certain elements in the solutions which exhibit 
it. It has thus become an object of importance to devise 
means for facilitating the performance of the observations by 
which the existence of this property is detected and its amount 
measured. 
The general nature of all methods and apparatus for this 
purpose must be obvious on the first conception of the pro- 
perty itself. But they may admit of considerable modifica- 
tions in their details, so as to be more or less applicable un- 
der different conditions. 
The most ample details as to the methods of experimenting 
have been given by the original discoverer of their singular 
phenomena, M. Biot, in several memoirs in the Annales de 
Chimie +; he has also devised a most complete and accurate 
apparatus for the purpose, which may be procured from Paris 
made under his direction. Without in the slightest degree 
meaning to disparage the excellence of that apparatus, or in- 
deed the necessity for it in all refined and accurate researches, 
yet for the more general purposes of the chemical inquirer, 
and especially for students, it must be allowed that its com- 
plexity, difficulty of adjustment, and expense must stand much 
* Communicated by the Author. 
{t+ See also Taylor’s Scientific Memoirs, vol. i. p. 584 and p. 600. Eb. ] 
Phil. Mag. S. 3. Vol. 22. No, 145, April 1843. R 
