Newsgroups: sci.chem
From: B.Hamilton@irl.cri.nz (Bruce Hamilton)
Subject: Re: Help wanted on adhesives
Date: Fri, 21 Feb 1997 16:34:02 GMT

"Stephen A. R. Carino" <carino@chem.ufl.edu> wrote:

>On Thu, 20 Feb 1997, Bruce Hamilton wrote:

>> AFAIK, Mucilage is the hot or cold water extract from plants.
>> Animal glue is somewhat different, perhaps based on crude
>> gelatine?

>isn't it that mucilage comes from cartilage and that the latter is a
>polysaccharide from which gelatine is also made of?
>
>correct me if i'm wrong...

You're wrong. Mucilage comes from the water extract of plant material.
Gelatine is the principal constituent of animal glue, which is derived
from the waste skins and cuttings from tanyards together with bones, 
skins, tendons, horn piths etc from slaughter-houses.

The above delicious mixture is washed with water and then
treated for up to 30 days by soaking in limewater to remove 
hair and flesh. The product is rinsed with several washes of
water, sometimes also with very dilute hydrochloric acid to
prevent bacterial decomposition. Bone glue was made from
bone meal that had been washed with benzene of carbon tetrachloride
to remove grease.The degreased bonemeal was washed with 2-5%
hydrochloric acid for 2-5 days to remove the Ca3(PO4)2 which
leaves about 30% of the original mass as a soft mass (collagen).
The acid wash water was treated with lime to yield Ca2H2(PO4)2
which was used to make bone china or as a fertilizer.

The above feedstocks are placed in a pressure kettle and sequentially
extracted for 2-6 hours with water of increasing temperature. 
The first extraction is usually at 70C and provides the best
quality glue. Extractions are continued until no more glue is
recovered.

       Bruce Hamilton