I gave DS a lovely compass keyring, made by Dalvey of Scotland, as a HS graduation present. He has been using it at college. He called tonight to say that it is leaking. Does any one know what the fluid in a compass is likely to be, and whether it is toxic? And would it be possible to have the thing repaired? I have already emailed Dalvey, but as they no longer make these keyrings I don’t expect that they will repair it.
Possibly alcohol or kerosene. Can he tell by the smell?
He said that it smelled like trumpet valve grease. I’m not sure what that smells like.
Does he have a friend majoring in chemistry with access to analytical equipment? Ask the friend to take IR spectrum of a small sample of the fluid and compare the spectrum with library spectra (works like fingerprints). An NMR would also work, I suppose. 
If it smells like grease, it is likely a hydrocarbon… kerosene?
I’ve seen a few websites that say to use mineral spirits. You can get that at any Lowes or Home Depot. It is a little bit oily, and I use it to clean paint and tar off my hands.
Kerosene seems likely. I’m going to try to get it repaired. I have not heard from Dalvey yet, but I will try Madison85’s link and I also found a repair service in the US.
Thank you all for your suggestions!