Check out this really cool chemical reaction experiment! Did you know that you can write secret messages using baking soda and blackberries? Simply dissolve 1 table spoon of baking soda in 1 cup of water. Then using a Q-tip, write your message on a blank sheet of paper. Let it dry for about 10 minutes and watch your message completely vanish! Lastly, in order to make your message visible simply rub your blackberry across the paper and watch your message appear!