I read in a book that an aqueous solution of ethanol produces a constant-boiling mixture which contains 95.6% ethanol and 4.4% water. This is called rectified spirit. I googled the word "constant-boiling" and I came to the conclusion that it's nothing but azeotrope. But it isn't clear to me how rectified spirit is prepared. Is it true that whatever volume of alcohol is taken in water, rectified spirit is formed? Also, I would like to know how absolute alcohol is prepared and what it is. The book says that when rectified spirit is(???? heated under reflux over quicklime ????)for about 5 to 6 hours and then allowed to stand for 12 hours, on distillation, pure alcohol is produced. What is heating under reflux over quicklime? I understand heating under reflux but what is the use of quicklime here ?