Ross Koning wrote on 14/3/00 6:29 pm
>I too had permanence problems. I think the volatility of
>iodine plays a role in that.
In my teaching laboratory I have a leaf with an iodine / starch positive
from an old b/w negative which I mounted between plastic (OHP) sheets and
sealed the edges with sellotape. It has survived for years and I keep it
in reserve to pass round as "Here's one I prepared earlier."
> Maybe it's the boiling in alcohol that helps them keep - you
>might not have wanted to do this in a 4th grade class! - NH
My leaf is also a geranium leaf and I DID boil it in alcohol first - so I
guess Nancy could be right.
Dr. John Hewitson (Oundle School)
Bramston Garden Cottage, Oundle, Peterborough PE8 4BG UK
Phone and Fax +44 (0) 1832 272209
email john_hewitson at breathe.co.uk