Is it possible to get a useful starting gravity reading when not everything is dissolved or suspended, but you know it ultimately will be?
Some context: In my pre-hydrometer days, I made a few cysers / honey ciders that really only amounted to apple juice, honey, and yeast. I never was able to get the honey to fully dissolve, it just went straight to the bottom and sat there, silently mocking me. After initially being concerned, I RDWHAHB'd, figuring the yeast would find the honey eventually. And they did! A couple weeks later, the honey layer was gone, leaving the beginnings of a delicious beverage behind.
(In hindsight, I wonder if this accidental timed release mechanism meant the yeast weren't as stressed as they could have been, actually improving the final product. But I digress.)
Back to my question: if I understand the physics of a hydrometer, it measures the buoyancy due to displacement of the water+stuff (dissolved/suspended). So it seems to me that anything not dissolved or suspended (thus resting on the bottom) will NOT be reflected in the gravity reading, any more than if I were to throw in a handful of marbles. Am I correct in my thinking here?
=== EDIT: anyone who comes this way, the following wasn't quite right, see answers below ===
If so, then it seems like it should be possible to calculate an "effective" OG, since I know how much adjunct I'm adding. If:
starting gravity = (density of wort)/(density of water) = ((mass of wort)/volume)/((mass of water)/volume) = (mass of wort)/(mass of water) # since volume is equal = (mass of water + mass of stuff)/(mass of water) = 1 + (mass of stuff)/(mass of water)
then for the purpose of illustration and intentionally making the math easy, would adding 50g of honey to 1L of 1.050 AJ lead to an "effective" OG of 1.100? (assuming 1L of water = 1000g)