No, you can't just let it evaporate at room temp as you won't remove all the water that way.
Drying under heat is the gravimetric method. It is what the others need to be tied to to understand what they mean, but it is not as simple as heating and weighing.
Conductivity is the standard that oceanographers use now (since 1978 or so), and I'm not sure why you want to look for something else. They have done all the hard work already to show how it relates tot he solids in seawater. 35 PSU (Practical Salinity Units) is now DEFINED as seawater with a conductivity equal to the conductivity of a potassium chloride solution containing exactly 32.4356 grams in a mass of 1 kg of solution (53 mS/cm).
For a long time (before 1978) people used chlorinity by titrating with silver nitrate, but I doubt you want to do that either. :D
I see what you mean. Well i wanted to not use conductivity because im worried about poorly desighned electronics, a faulty probe, wrongly made calibration standards, unknown impurities in the standard possibly causing inaccuracies, and air bubbles of large and microscopic order. And what about temperature? What if its not calibrated properly either. Plus i wonder about radio wave interference and magnetism. Lol. Lots of uncertainties with conductivity but i may be just over exaggerating.
With a refractometer there is a little less uncertainty. Because it has a lot less points of failure unlike an electronic machine with its circuits and such. But the same comes to mind about air bubbles over the collection plate, fairly imprecise scale to read it, and calbibration uncertainties like impurities. Not only that but how can i verify that its ATC is functioning properly?
With a hydrometer i worry about air bubbles raising it, impregnation of the plastic swing arm of water, possible mineral deposites. With the glass floating version how can i know its been made correct? Then how do i know my thermometer is measuring accurately?
This is why i thought evaporating the water then weighing it would be the most accurate- no error just salt in the end. But you proved its not as easy either. So now im still on the lookout for the easiest most reliable way of getting salinity. :)
Im thinking boyancy (floating glass hydrometer) and a nist thermometer is probably the best way considering uncertainties of the above. The forces in play here dont change much, and youd know ita broken easily, without a degree in electronics, or science right?
