his/her chemistry homework while in school.

Have you ever had a salt shaker stop working? Ever hear of putting some grains of rice in them to keep the salt flowing? This reference claims that small amounts of magnesium are in salt-- this is the first time I have heard of that:
http://en.wikipedia.org/wiki/Hygroscopic

SlowMag AND the generic have magnesium chloride as the active ingredient. And like table salt (which is mostly sodium chloride) it will draw moisture from the air to itself. This is called hygroscopic behavior.

So the active ingredient in the SlowMag is the MAGNESIUM itself!

Both generic and the brand name will sweat if removed from a tightly closed container. Most pill minders are not safe from the atmosphere. If you try and keep SlowMag for many months after the initial breaking of the seal, it will sweat right in the bottle. This does not affect the actions of it, but it does taste salty if you swallow one. Like many delayed release forms, there is an immediate release layer, with a matrix for later absorption in the middle.

I had 10 semesters of chemistry when studying for MY degree.
I guess pharmacy schools have changed. 2 of the 10 were inorganic chemistry with 8hr labs/week, where this principle is taught!