Gas wash bottles have a GL-45 thread on both the Dispersion Tube and Bottle.

The pressure tight connection is made with a GL-45 to GL-45 coupling. This connection eliminates the need for grease and springs. The dispersion tube has removable hose connections that provide safe attachment and removable of rubber tubing.

Supplied complete with: 

1095-18, Adapter, Coupling, Threaded, Straight
[2] GL-14 removable hose connections Item #2294-10