5 years ago
Triffid raises whether the air in a spray bottle that enters to fill the space vacated by the liquid is significantly deleterious to the 'fume. I doubt it, as I doubt that even if ^all^ the oxygen in 50ml of air were to oxidize fragrance molecules in 50 ml of 'fume, it would do more than a negligible damage - or even 90 to 10 - or perhaps even 95 to 5. Perhaps not but when there is literally a trace in the bottom will the oxidation be significant; especially as, if uw were to analyse the air in a bottle of 'fume, it would probably transpire that it had nearly the full complement of oxygen (@bout 20.95%), wherefore that only a small fraction of it had been spent oxidising fragrance molecules. This is what I like about spray dispensers - only the minimum quantity of air required to fill the volume vacated by the 'fume enters the bottle. (If uw are still concerned, uw could enforce a discipline of only ever spraying it from beneath an argon-arc welding hood so that only argon enter (please abide my little sarcasm - it is not meant maliciously!).) This is as opposed to bottles with a stopper that is removed whenever uw broach it, so that a fresh draught of air enters each time, and a large proportion if the air, or perhaps nearly all of it, is replaced.
Actually, now that I consider it more carefully, this last argument about stoppered bottles is inconsistent with my adduction that only a small fraction of the oxygen in a spray-bottle is used up. Still, I have always had an ¯eingefühl¯ that spray bottles are greatly superior to stoppered ones in this regard. Maybe my argument is misproportioned as a whole.
Actually, I'm beginning to see now that it's quite a complicated question: because if only a small fraction of the oxygen is used up, there will not be much difference between a spray bottle & a stoppered by reason that the fresh draught of air entering the stoppered bottle will be little different from the (slightly) oxygen-depleted air that was in it before its being opened; whereas if a significant fraction of the oxygen is consumed oxidising fragrance molecules, there will be a significant reduction of pressure in the spray-bottle, and the volume of air entering when the valve is depressed will greatly exceed the volume of liquid that departs.
Oh no! It's really furunculating complicated! Well, thank-uw for prompting me to consider the matter more thoroughly anyway!
But, also, this whole argument concerns oxidation only; and I think there is ^no possible doubt^ that spray bottles are superior apropos the matter of evaporation.
Maybe I ought to consider the welding-hood trick for real!