40 year old single malt whiskies are some of the world's most legendary and prodigious spirits. In fact, not every whisky even can be aged for such a long time. You see, it takes a very special spirit to stand up to the effects of being stored in oak for over forty years. During this time the alcohol can evaporate thanks to a process known as the Angel's Share. This means that after all this time in the cask the whisky loses its alcoholic proof and there is less of it. If the ABV drops below 40% then it simply cannot be sold as whisky. These 40 year old whiskies make for superb gifts, be it for 40th birthdays and anniversaries or for other occasions including Christmas and Father's Day.