Yep. Good job. You are now a scientist. When ice and water are together, the salt goes mostly with the water and only a little bit is in the ice. So the lava, which is mostly water, will have most of the salt in it. Try it! Take some salt water and put it outside until it is partly frozen (or put it in a freezer if you live in a Southern climate). Take a frozen piece and rinse it off and taste it. How salty is it? Taste the part that isn't frozen yet. How salty is it?