Unusual gunpowder flask

[Kmaddock]

Hi
I just picked up a job lot of items, interesting box of various shot and powder dispensers
All are standard enough mid to late 19 century
However this one has a mechanism I have never seen before
It is silver hallmarked on the neck of the flask but I think the main components are nickel
It looks as if you inverted the flask, opened the lever to dispense the powder, filled the cap and then the cap swivels through 90 degrees and you can then pour the powder into the gun.

Lots of mechanism and complicated to manafacture.
The retaining leaf spring to stop the cap from falling open is broken and the adjustment mechanism to allow various chardes to be dispensed is jamed

The flask itself is quiet rotten but the mechanism is overall not too bad.

The weight is in drams and it has the word patent on it so I assume English.

Can anyone shed some light on if this is a rarity, I def8nstely have never seen similar

If anyone can identify hallmarks I would be delighted to know any info in this regards as well

Regards

Ken

Size of flask is standard approx 150 mm rifle, shotgun flask