Suppose you honestly didn’t know which was the organic layer? Also suppose that you don’t have a handbook to look up that crucial piece of information that would allow you to decide. Zubrick offers a simple test to make this determination which involves testing a few drops from each layer in a test tube containing a small amount of water... well that’s too much effort and more dirty glassware! Actually, there is an even simpler, faster thing you can do and you needn’t take anything out of the sep funnel!
What could you do in this situation?