The Iodine Charge is used in a Rainmaker to produce rainfall. It can be used by right-clicking on the Rainmaker with one in-hand or by automatic BuildCraft pipe input. Note that the Rainmaker must not be currently charging or it will reject the item. To stop rainfall, see Dissipation Charge.
The recipe is made in the Carpenter. A crafting grid is used for illustration purposes.
Up to version 1.4.4 (called Iodine Capsule)
Version 1.4.4+ (called Iodine Charge)