# How would you measure the amount of dissolved salt in the ocean?

This site reports that the salt content of sea water is $35 \cdot g \cdot {L}^{-} 1$.
This site gives details on the volume of the world's oceans, but you will probably have to convert the units, and there is the usual muddle between $\text{US}$ and $\text{imperial gallons}$. Good luck.