>My preferred method is to transfer the material into alcohol for a few days,
>then dry it thoroughly.  It dries virtually odorless after the alcohol
>treatment, and can then be stored indefinitely with no special requirements -
>just like sand.
>Paul M.


Specimens preserved in alcohols can decompose once the alcohol has
evaporated. Formaldehyde denatures the proteins in such a way as to prevent
subsequent rotting ie it fixes them. Formaldehyde needs dilution and
buffering, or it will etch shells and over time may dissolve them
completely. Commercial formalin is an aqueous solution of formaldehyde, and
should be futrher diluted down to 4% of the commercial strength
.
Andrew G