Why are you asking this?

Also I dont understand why you are talking about the density of LSD, LSD will typically be synthesized and crystallized in salt form like tartrate, so it's a solid, not a liquid. Then you dissolve it in an appropriate amount of ethanol, not water, to lay in blotters. Density should be totally irrelevant.

And yes your math is off. If humans were mouses, then 50mg/kg LD50 = 3500mg=3.5g for a 70kg (around 150 pounds) person, not 8.25g.

Here's a relevant link: Erowid LSD (Acid) Vault : Fatalities / Deaths

Considering at least some of the thumbprint stories are true, then the lethal dosage might be even higher than we imagine. 

But as with mostly everything in life, there's a law of diminishing returns , more isn't necessarily better, and therefore you dont need to ever get even close to that lethal dose.  Also, basic safety precautions should make sure you are not ever ingesting accidentally such large amounts.