Just to update everyone, I'm thinking that this is indeed Calcium Chloride. Yesterday afternoon, I decided to take a few more pictures to illustrate what the granules actually look like. I left the lid off of the container while I transferred and viewed the pictures. When I went back to the jar to cover it, I noticed that the granules were glistening with moisture. As I understand it, Calcium Chloride is hygroscopic, while Sodium Citrate is not (at least, not according to Wikipedia). I e-mailed some pictures to WillPowder, and they replied that they would look into it asap. In the meantime, I've ordered some more Sodium Citrate, and hope to try the recipe later this week. Thanks to those of you who suggested it might be the wrong thing. I'm glad I posted a picture. Otherwise, there would have been a lot more wasted cheese in my future.