Well thanks for all the feedback everyone.
I've now got some pics of the woods in question, which might help clarify things.
This is the mystery wood, which smells a bit like incense when cut:
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scan is a bit lighter than the actual wood, but pretty accurate otherwise on my monitor (I colour corrected it). It's a bit orangey in hue in fact. Although I have waxed it and there was a bit of colour in the wax - not much though.
This is the box I'm putting the lids into:
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you can see, it has a rosewood veneer on the outside - typical i believe for a Georgian or early Victorian box.
Here's the inside shot with the new lids in place:
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just don't look smart enough I think. I need something with more of a gloss, more noble looking. You can also see that the box is made of solid mahogany, now visible on the inside of the lid. Originally the lid was covered in paper, with a love-letter flap covering it - but this was all too perished to be salvageable. I've also waxed all the inside - sacrilege I know for any antiquarians out there - but I've decided that this is never going to look like the original (sewing box) so I might as well have it the way I like it!
Here's a close up of the lids in situ:
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's also annoying that the grain is running the wrong way on the top lid! I had to do this as there wasn't enough wood (there are also some "secret bottoms" below which I replaced) to go round but on reflection I think that it's a major mistake. To be honest, the question of grain direction hadn't even occured to me when I was cutting the wood!
I'd be interested to hear a) whether you all agree that this is Spanish cedar and b) whether you reckon I should start again with a more suitable wood or maybe even veneer what I've got (I have some mahogany curl veneer I could use).
Now about that Anglo-Indian box I mentioned that smells of insecticide...
Here's a picture of the wood:
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's the whole box:
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's 18 inches across
Here's the inside:
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had forgotten but somebody had written a note inside saying it was made in India in 1909 by a Chinaman from "sola pith". As you can see it has a lovely red colour and a great sheen. It's also not as hard as I had thought. i think I used Danish oil on this one - the only problem was that the oil took forever to cure and it's still a bit sticky to this day (3 years later). I think there must be something in the wood that impedes the curing process, perhaps the same thing that smells of insecticide.
As for whether these are wood smells or have been added later... Personally I think they are from the wood. After all, mahogany has a very characteristic acrid smell when sanding. I once fixed a very hard and brittle black African wood candlestick - possibly ebony - and that smelled so acrid when sawn it gave me a headache. Pine of course has a really strong smell. And there's sandal and balsam as someone mentioned. I agree with George's point that these are probably natural defences for trees against insect attack.