How Not to Determine If It's Limestone

I said, "Farmer, I think I found the limestone powder you were looking for," and handed him an unlabeled bucket of white powder that had been sitting in the greenhouse.  What did he do?  He looked confused for a second, told me thanks but that wasn't the bucket he was looking for, and then he ATE SOME to see what it was.  Farmer's thanatos instinct appears to be overdeveloped.