An egg osmometer

Place some dilute hydrochloric acid or strong vinegar in a shallow dish, likeas a saucer, to a depth of about one centimetre. Hold the large end an egg in the acid unless the shell has been eaten away on the end leaving the thin membrane exposed. Rinse the acid from the egg. With a shar instrument work a small hole by the shell at the other end. Insert a soda straw or a length of glass tubing by the hole into the interior of the egg. Seal the opening around the tube with house hold cement or sealing wax. This must be absolutely tight. Place the osmometer in a glass of water and let it stand for a few hours.