Originally Posted by Pukka Bundook
As stated above, this type of top was a safety device, as occasionally 'normal_flasks would blow up on charging a barrel containing a spark.
Some tops looked like the regular, but were warranted fireproof.
This type of top appears to have been used more in France than the UK,.
Anyone with the Powder Flask Book will see many variations.
Sorry though, I don't own the book!
It's a nice one to have, and much scarcer than the usual types.
I don't have the best known book by Riling but similar flasks appear the book by Martin Rywell but don't get much of a mention in the script, I've looked in a James Dixon of Sheffield catalogue from 1883 and it has clear drawing of this type of dispenser fitted to different styled bodies, one is listed as model No.5054, having a patent top.
Additionally with reference to the markings.
Quote From Martin Rywell.
Dixon & Sons. James Dixon was a firm founded in 1804, their mark was, Dixon, until 1806. From 1806 till 1830 their mark was a D and S separated by a rose