half full/half empty

[gontofe]

I've got a bottle of beauty product with a liquid inside. I would like to know how much is left inside, the problem being that the bottle is opaque and dark coloured, so I can't hold it up to the light. How can I tell how much is left (floating it in water?)

[Jenny Tools]

place a long thin stick in it, pull it out and see how far up the stick it shows

[gontofe]

very clever, but it's got one of those spray tops that you can't unscrew (don't know if you know what a Ketsugo bottle looks like)....

[spiff]

If you have another (full) bottle,weigh it.Weigh the one you are trying to assertain the contents of,then compare the two.x

[spiff]

Also, if you don't have another bottle,weigh it anaway. The bottle should have a label saying how many grams of product it contains.x