I keep a bottle of Mackenzie's Smelling Salts in the car - handy if i get that "nodding off" feeling which can come even if I'm not tired.

However they're not always available here so I did wonder about making them.

Ammonia and menthol?

But would the crystals be menthol or a salt - would either of these be dissolved by the ammonia? Or is there a solid form of ammonia?

I'm afraid i don't have the answer to your questions Elaine but wanted to say that that is a great tip about keeping smelling salts in the car. 

Thanks for sharing!

Don't think I've ever smelt smelling salts.  Didn't even know you could still buy them. 

Smelling salts used to be made from ammonium carbonate, which gently decomposes to give a little ammonia gas in the top of the bottle. Ammonia liquid would be far too strong and would need to be stabilised - not sure I would recommend making these at home, but, if I wanted to make a product with a similar function I would mix some ammonia (few drops) into some fullers earth (I would use cat litter actually) - the FE would absorb the ammonia and gently release ammonia gas (by gently release, I'm talking in chemical terms, I might still blow your head off!) A few menthol crystals could also be added.
Take care!

Thanks Scott - I didn't think liquid ammonia could be the answer and wasn't aware of ammonium carbonate.

Would coarse pumice grains work ('cos I don't think cat litter is available in small amounts and our cat doesn't use/need a tray).

We've a bottle of Mackenzie salts in the first aid box, bought not that long ago. I can't stand the smell but John swears by them when he's stuffed up. Think they are still fairly easy to get hold of.

They are generally - but not necessarily in Corwen.

I've often wondered how to make them though.

(just looked up sal volatile: