Re: Gelatin + ferric nitrate

Dear Brandon's Mom,

I have done some digging but have not been able to find anything on the 
slime generated from gelatin and ferric nitrate.  Gelatin is composed of 
collagen, which is a protein.  Crosslinks can form between collagen strands 
by several types of chemical reactions involving the carbonyl groups 
(double bonds between carbon and oxygen) of the amino acids which make up 
the collagen.  These crosslinks could function in the same manner as the 
crosslinks formed by boron in the boric acid-poly(vinyl) alcohol slime.  
Ferric ion does not form the kinds boron does, so my suspicion would be 
that the ferric ions act as catalysts for the reactions occurring in the 
collagen, rather than actually participating in the formation of bonds to 
form the crosslinks as boron does.  Ferric ion is a good catalyst for 
reactions involving carbonyl groups.  

Collagen is the most abundant protein in the body, and makes up most of the 
mass of skin, tendons, bone, blood vessels, the cornea, and membranes.  Any 
biochemistry textbook will have information about collagen including its 
chemical structure, as well as its bulk properties and how crosslinks are 
formed in vivo.

If you want to do additional searching on this subject, I would suggest 
looking for books or web sites on the subject of chemical demonstrations.  
There are a number of such books that have been published.  An article in 
the Journal of Chemical Education  1986, Volume 63, pages 57-59 on the 
polyvinyl alcohol/borax slime contains references to other similar 
demonstrations which might be fruitful.  This journal can be found in most 
college and university libraries.