Gluing boiler
The bone glue and fish glue where the only wood glues up to 1940's, then came more modern glues (white glues).

Gluing with old bone (or fish) glue is totally different compared to the modern glues. This glue has to be
dissolved to water and heated up to 60-70 ° Celsius.

To do this old times the carpenters had a glue boiler looking like coffee pan and there inside was second barrel for glue.
I did make a modern version of this.
An thermostatic water boiler is very fine for this,
you can adjust water temperature to 60-70
° Celsius.
Then for glue I have second aluminum barrel hanging from boiler cover.

You add a bit of water to glue and then let is melt.
The "open time" of the glue can be adjusted with the amount of water, more water longer open time but also longer drying time.
The open time is longer also if you heat the spices you are gluing to.

The brown rectangle sheet is bone glue as it is sold.

For more info see next links: