Well, the easiest way is the ole taste buds…calcium chloride will taste like salt
gypsum will taste like drywall dust and chalk will taste like chalk…not much difference
between the flavor of gypsum and chalk IMO…chalk will prolly be in a stick form.
The last pack I bought said “edible”…go figure
I can’t say I’ve tasted them, but I’ve noticed that CaCl is more granular than CaSO4 and CaCO3. It’s also really hygroscopic, so it tends to end up as a brick once it gets exposed to air. Hmmmm . . . CaSO4 will dissolve in water more readily than CaCO3 too. I’m sure there are other ways to tell, but these come to mind right away.
I’ve tried the taste buds route before – unreliable, for me anyway, as everything tastes like powdery chemicals.
I’ve purchased brew salts from at least two different sources. I don’t find the packaging or the form it comes in helpful.
I prefer brew salts that are in the form of fine microbead granules. It makes it so much easier to weigh out and doesn’t cast a bunch of powder all over the table. It is also easier to transfer when outside on a windy day w/o fear of a “Big Lebowski”-ish mishap. http://www.youtube.com/watch?v=XczJqembVto&feature=related
I’ve gotten brew salts that aount to nothing more than fine white powder (think confectioner’s sugar) in a cellophane bag. Sometimes a sharpie has been used to write it down, other times a label has been put on the bag.
It’d be nice to use a drop of vinegar or some simple household chemical to confirm some white powder is or isn’t x, y, or z.