What you need in it is a cartridge pen, is a rubber bulb syringe, often called a baby ear syringe.
The opening of the spout fits normally quite well over the spike that pierces the cartridge. Need a Bathroom sink, half full of water.
Suggest the first time, fill the bulb syringe then put the spout over the spike....after that just keep squeezing. Sooner or later the water will go through clean.Then take a paper towel, fold it, shake the pen like an old time thermometer....fold the towel....put in a cup and wait 3-5-8 hours for all the ink to wick out into the paper. Then the nib is clean.
If you can find a needle syringe....go to your pharmacist, tell him what you want it for....a wide long needle and a 10-12mm syringe to fill that cartridge with ink of your choice.
I've always found cartridges to be very expensive even back in the '50's....so refilling a cartridge is cheaper even if using expensive ink, than buying a cartridge.
I don't know what cartridge that is, but Pelikan, Waterman, and Parker ware 'international' so might fit. I chase piston pens so am behind when it comes to cartridges.
You have a converter that fits your pen, so you can save money on ink.
You have already learned a lot.....but one needs to go to Richard Binder's site, it is the bible of fountain pens; info on nibs, filling systems, good advice on inks and so many grand :puddle:pictures of beautiful old pens.
Will take you some three days to read through.
Pay much attention to his article on Metal Fatigue ....so one don't press too hard, too often.
With a nice friendly smile we will push you off the Ink Cliff...............we are living in the Golden Age of Inks.
You will be caught by a nice thick pad of good to better papers.
(The Golden Age of Pens died in 1970...The Golden Age of Paper @ 1980.... :crybaby:And no one told me about it..........sigh cubed....but by then I was a Ball Point Barbarian. Don't think anyone knew Paper had died....it wasn't in the newspaper's obituary Colum. 
Writing is 1/3 nib width/flex, 1/3 paper and 1/3 ink and in that order.
When you get over to Ink Reviews, pay attention to our Ink Guru, Sandy1 
, with 4 normal width nibs....on 4 papers.....(If one goes back far enough there will be 7 fine papers. ) It was such a great shock 
, with different nib width or on different paper....the ink was so completely different one can't believe it's the same ink.
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Do strive to keep the fountain pen behind the big index knuckle of your writing hand, not before it like with old style...pre-gel ball points. Let the pen rest at 45 degrees right after the big knuckle, 40 degrees at the start of the web of the thumb.....or if the pen is heavy or long, let it rest in the pit of the web of the thumb.
The Key is ..... let it rest...........don't force it to be at one angle or another, or you will be using too much pressure just to hold the fountain pen.
Hold it lightly, like a featherless baby bird.
:angry:Don't make baby bird paste!!!
And you made good progress on what your nib is............ :notworthy1:Looks like a real fun nib!!! 
900 silver is called coin silver in the US.....the Germans had 800 silver to about middle '30's when they went to the Scandinavian 835....in they could export it easier.
There are Russian silver at @ 875, coin silver at 900, Sterling silver is 925....and there is a Russian silver at 937(= 90/96 Zolotniki & 84*** zolotniki = 875%)) also.....believe there is a Scandinavian silver at 935 also.....depends somewhat in what era....and or country. the 935 could be Norwegian.....
*** Yep, one can learn something every day here, even after years....and there is no test so learning is fun.
Edited by Bo Bo Olson, 02 February 2019 - 18:16.
