Lactose fermented onions - a recipe?

[RPh_Guy]

So your point is that to get this precisely right and not die everyone should pull out their physics and chemistry books to get the proper expansion coefficient of water not to mention that they need to precisely measure the water temperature to 3 decimals? I understand your point but these calculations do not need that level of precision!

I agree, the brine percentage doesn't need to be super precise.

This formula is simple and doesn't require any textbook:
[grams of salt] = [% brine as a decimal] * [total volume in mL]

Relax, we're just discussing a little science.

To even get to the precision that you are wanting, one would need to measure the volume of liquid to at least 3 significant digits.

Nah, as I said:
To get 1L of 4.0% salt by volume, one only needs to measure volume to 1.0 L and salt to 40. g.

All these numbers are 2 significant figures, and this level of precision is easy to reach with inexpensive instruments.

If you choose to measure the water by weight, that does complicate matters if you want to use % by volume to be on the same page as the rest of us.

Here's the formula for calculating the amount of salt w/v but measuring water in grams:
[grams of salt] = [% brine as a decimal] * [grams of water] ÷ [density of water] ÷ ( 1 - [% brine as a decimal] ÷ [density of salt] )

 

[renrutle]

I agree, the brine percentage doesn't need to be super precise.
Relax, we're just discussing a little science.

Agreed.

For those who don't have any scales etc. using ~1/4 cup salt per quart of water will give a brine of ~4%. You can then adjust up or down from to suit your tastes.