Back in the early 70's I heard rumors that Lionel was going to quit producing smoke pellets. I went down to the local toy store and bought all that they had (about two dozen plastic containers). I decided to try t o duplicate the pellets. I gave my brother-in-law (a master's student majoring in chemistry) a bottle to analyze at school. He went to one of his professors who read on the bottle harmless even if swallowed. He popped one into his mouth and said it's not a salt. The product was a chemical that sublimes. As it is heated it goes from a solid to a liquid and then to a gas, but when it is cooled it goes from a gas directly to a solid which looks like smoke. We found a chemical that had these properties and I bought a pint jar for about $8.00. I made a pill press and these pills worked quite well. When I went back to order more the price had jumped to $90.00 a pint as this chemical was now being used to produce lasers. Thus ended my project.