is glue really made from horses or cattle bones?

Question

and if so how is it possible?

Answer 1

Certain types of glue are indeed made of animal subproducts - bones, skin, etc.
This is called animal glue and is of brown - yellowish colour and has a strong smell, reminding of raw animal hides.
It can be used by mixing with water and is biodegradable. It was comonly used in bookbinding and carpentry (for gluing wooden pieces to furniture) and is no mostly eliminated due to more modern and resistant synthetic adhesives.
It is in fact a type of protein extracted by boiling of bones and skin of animals. You can see that if you boil a lot a meat and bones from an animal (or bird) in a certain amount of water, then continue to boil the remaining "soup", you will eventually get a thick viscous product that is kind of "sticky" when cools off. This is generally how the animal glue is made. Further, it is filtered and refined, dried and then ground into a powder. This is the glue, that can subsequently if mix with water turn into an adhesive.
As I said, it is no longer used... It might prove interesting that another "old adhesive", called "caseine" was made from milk byproducts and cheese derivatives. Caseine is in fact a protein found in milk and cheese. This glue was also water based and used too in bookbinding, carpentry and aircraft model making.
All the modern adhesives are synthetic resins or polymers.

Answer 2

Read on.. This is from WIlkepedia

An animal glue is an adhesive that is created by prolonged boiling of animal connective tissue. These protein colloid glues are formed through hydrolysis of the collagen from skins, bones, tendons, and other tissues, similar to gelatin. The word "collagen" itself derives from Greek kolla, glue. These proteins form a molecular bond with the glued object.
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* Hide glue is used in woodworking
* Hoof glue is also used today in woodworking, specifically cabinetry
* Rabbit-skin glue is used in the sizing or priming of oil painters' canvases.

Answer 3

Hide and bone glue. Bones or hide are boiled up and the long protein molecules are extracted as gelatin and glue gunk.

That book of matches you have might have been glued using the remains of a cow bone

Answer 4

I know it used to be made from horse hooves... whether it still is I don't know. I doubt it though.

Answer 5

More boots on the ground, more targets to hit