60 ml nic = 6% volume
100ml nic = 10% volume
What do you mean by "60 ml nic"? Do you mean pure nicotine? Or do you mean the more common 60mg/ml solutions of nicotine in PG or VG?
Now, PG and VG aren't exactly water, but they are close enough that we can use water's handy dandy correspondences between volume and weight:
1 ml weighs 1 gram = 1000 milligrams = 0.001 kilograms
What makes this confusing, even for us who have never used anything but the metric system, is that the correspondences aren't milli-milli, centi-centi or deci-deci.
They are:
Litre = Kilogram
Deciliter = Hectogram
Centiliter = Decagram
Milliliter = Gram
Now, one Gram is 1000 Milligrams, one Litre is 1000 Milliliters.
Where this gets really confusing is the fact that one Litre (water) weighs 1000 Grams, and one Gram (of water) has the volume of 1 Milliliter.
We snotty Europeans often like to say that the metric system is sooo logical and simple and we just can't understand why anyone uses anything else. This is true, but we do forget that if one doesn't have an everyday "feel" for just how much volume is in one litre (a bit more than a NA quart), how much it weighs (a bit more than 2 pounds I believe), or how much 1ml is (1/4-1/5th teaspoon) and how much that weighs (1 gram - sorry I have no idea what the corresponding NA everyday unit would be), the names of the units can be very confusing.
So, in one ml of water, there is one gram or 1000 mg mass. Which is why 100mg/ml nicotine solution is sloppily called 10%, or less sloppily 10% weight/volume.
Units and precision matter!
Now, I would love it if some chemist or science teacher could explain the finer points of the volumes of solutions - what exact volume *does* adding 100mg of nicotine to 1 ml of PG give us?
I know that when I add a tablespoon (15ml) of tablesalt to a deciliter (100ml, a bit less than 4 fl oz), I do not end up with 115 ml salt water, I end up with considerably less (maybe 103 - 105 ml). And I can't quite believe the explanation is that tablesalt is 2/3 air...
