I put the methanol in a small jar because I didn't want to waste half a litre on one injector Petrol would probably work just as well, but do it outside.
If you're using something flammable then it is safer to have just a small amount in a jar, and it also leaves less nasty chemicals to dispose of - you have to change it after every cycle.
I could have done the same with the citric acid in a jar, and probably should to save corroding the bath.