Alyssa Ashley Vintage Civet Oil

I recently inherited a lot of vintage perfumes from my mom and one of them is Alyssa Ashley Civet Oil by Houbigant.  It's .48 fl oz in a black bottle.  I'm trying to do some research into this and learn whatever I can about it.  I've been told that it is quite rare and just trying to confirm that this is true?  My mom kept it stored in a box in the closet for decades, and I doubt at the time she bought it that she wore any of it.  When I shake the bottle, there's definitely liquid in it, and when I opened it, the applicator is coated in it, and WOW, what an intense smell.  One of my problems now is to determine how much is actually left in it.  I've been told to put it in the freezer for awhile and then take it out and put it in a warm place and see where the condensation forms on it.  Is this a good idea?  Would it damage the bottle or the oil?  If oil freezes and then thaws, wouldn't that water it down?  I looked online to see possible values on slope game this rare oil and it seems to go all the way up to $400-500 or even more.  Any info appreciated so that if I do sell it, I can appropriately and fully describe it to the best of my ability.  Thank you!  

The comments above won't help neither the thread creator to get her questions answered, nor will they make any dead animals, purportedly used and abused in making the thread creator's perfume, coming back to life. The commenters seem to equal a long since abrogated, immoral practice with the person who just happens to be in possession of something best described as a genuine antiquity, more of a historic artefact than the commodity it once was. 

Concerning the suggestion to freeze the bottle and then warm it up to see by where the condensation starts, how much is left in the bottle. I'm not sure whether it works, will the condensation even appear? If the bottle is well sealed I don't think it will get diluted. The real danger, if there is one at all to be concerned about, would in my mind be when the fragrance is warmed up again and for how long it is kept in this surrounding. Perfume, and indeed oil, is sensitive to high temperatures and also hasty temperature shifts can damage perfume, much in the same way wine risks getting damaged when exposed to frequent shifts in temperature. If deciding how much fluid is left in the bottle is of imperative importance, I could imagine trying it once. Getting an approximate evaluation of how much is left can be done by gently turning the bottle upside down back and forth. Simpler and safer, even though maybe not as accurate as one might wish for.