The absolute refractive index for pure water  is 1.33335 at 20 degrees
C for sodium light, lambda = 5893 Angstrom units  - see The Rubber
Handbook.
By definition, the refractive index of vacuum is 1.000.
So where was the value of 1.025 for sea water published?

Colin Izzard

> Date:          Thu, 9 Mar 2000 09:27:36 -0800
> Reply-to:      Confocal Microscopy List <[log in to unmask]>
> From:          Michael Cammer <[log in to unmask]>
> Subject:       Re: another ref. index question
> To:            [log in to unmask]

> Chemists and biochemists use this technique routinely.  Also, crossed
> polarization of transmitted light.
>
> At 10:03 AM 3/9/2000 -0400, you wrote:
> >Yes, for years  oceanographers have been using refractometers to
> >measure salinity of seawater; e.g. oceanic water at salinity 30 ppm has
> >the refractive index of 1.025 (distilled water RI=1.000). I have never
> >measured buffers, but if you could  get hold of a refractometer, you can
> >do a measurement  in a second.
>
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> *  Michael Cammer * Analytical Imaging Facility * Albert Einstein   *
> *  College of Medicine * 1300 Morris Park Ave. * Bronx, NY  10461   *
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>

Colin S. Izzard, Ph.D.
Department of Biological Sciences.
State University of New York,
1400 Washington Avenue,
Albany, N.Y. 12222, USA.
Tel. (518)442-4367.  Fax. (518)442-4767.
e-mail [log in to unmask]