灰化
Chalk \Chalk\, v. t. [imp. & p. p. {Chalked}; p. pr. & vb. n. {Chalking}.] 1. To rub or mark with chalk. 2. To manure with chalk, as land. --Morimer. 3. To make white, as with chalk; to make pale; to bleach. --Tennyson. Let a bleak paleness chalk the door. --Herbert. {To chalk out}, to sketch with, or as with, chalk; to outline; to indicate; to plan. [Colloq.] ``I shall pursue the plan I have chalked out.'' --Burke.