Try this web page.. remember to take your reading before the start of fermentation. http://www.apple-cider-vinegar-benefits.com/hydrometer.html
www.NaOH.com
for the purpose of measuring the specific gravity
alcohol specific gravity
1.0
hydrometer
I believe the reason behind using specific gravity is that it is easier to measure (especially when you're measuring it for a solid).
An instrument for measuring the specific gravity of fluids; a form hydrometer.
the measurement is called the specific gravity it works my measuring the wight of something towards its wight in water
to peform this conversion you need to know the density of the material (SG-Specific Gravity). Once you have this you multiply the tonnes by the SG
density = mass/volume. The unit of density is kg/m3
If it is water then 2.5 ml is 2.5 mg. If it not water then you need to know the specific gravity of the fluid and and convert ml to mg by measuring ml and multiply by specific gravity
It tests for Ethylglucuronide (ETG)--Alcohol, Creantanine levels, Specific Gravity, Nitirite, and ph.