The yolks may be kept several days and be as if just separated from the whites if they are placed in a cup previously rinsed with cold water and a pinch of salt added to them. The cup must be closely covered with a wet cloth, and this must be changed and well rinsed in cold water every day. When whites are left over make a small angel cake or any of the cookies which require the whites of egg only. When yolks are left over use for making mayonnaise.
Source:
The International Jewish Cook Book
