Lesedi was a sangoma, you know. I think she tried to put a curse on me because I was spying on her. But I wasn't really spying, I just thought that she was nice and wanted her to be my friend and then I saw the mask and I didn't anymore.

He is unable to select his crude, and often has to be satisfied with a worse residuum; nor is he in a position to dispose of his goudron as the latter, and for all these reasons, such a refinery is compelled to secure as high a ...

to exercise troops or horses;  to exercise one's brain with a puzzle

Originally, iron blue was potassium ferriferrocyanide, FeK[Fe(CN)₆], but it was found that potassium could be replaced with sodium or ammonium at lower cost and no sacrifice in properties.