Yvan,
		I am not sure that these mounting media are still
commercially available.
It is possible to produce your own naphrax starting with purified
naphthalene and formalin but it is a lengthy process and requires a lot of
patience.
The reference is W.D. Flemming. Journal of Royal Microscopical Society
LXXIV. 1954 pages 42-44.
I did make some of this in I think around 1970 but have used it all. I will
be happy to send the method if you are interested.
The refractive index of naphrax is quoted as 1.7. and is siad to have
better preservation of stains than canada balsam.
Barry

At 03:16 PM 1/10/99 +0100, you wrote:
>Whatever happened to mounting media with high R I? Does anyone know a
>manufacturer of one of these, or product names and manufacturers of other
>media with high NA as used for the preparation of diatoms :
>
>* Styrax		RI 1,58
>* Sirax		RI 1.66
>* Hyrax		RI 1.71
>* Naphrax	RI ???
>* Realgar	RI 2.549
>
>Thanks in advance...
>
>Yvan Lindekens, Belgium.
>
>
>