These are the most difficult to obtain chemicals suggested for the chemistry experiments in Year One of the Four Year Plan. Only those chemicals are included that are difficult to find or are usually sold in large quantities with correspondingly large costs. Chemicals that can be purchased at the grocery, pharmacy, or hardware store are not included. Silver chloride is not included due to its extreme cost. It is more expensive than all the other included chemicals put together! Magnesium and lead nitrate are available separately.