be released sequentially thus with the top wall 64 of the container 61 exposed to the coolant flow when the concentration of corrosion inhibitor decreases below a predetermined level or the corrosiveness of the coolant increases the scored portion 65 will pit and corrode until penetration of the wall allows the coolant to contact the inhibitor portion 71 and release the inhibitor into the coolant stream this cycle will repeat itself for each of the partitions 66 67 and 68 to retain a proper corrosion inhibitor level over an extended period of time although shown as a single container wall 62 with intermediate partitions the container can also be formed as several individual containers joined together such that the wall 62 would become four short cylindrical wall portions with the top wall or a partition forming the end of each short container fig1 and 14 illustrate an eighth embodiment of container assembly similar to the foil packet assembly of fig6 and 7 this assembly comprises an inner container 75 having a cylindrical side wall 76 a bottom wall 77 and a top wall 78 secured thereto and filled with corrosion inhibitor 81 the top wall is provided with a scored or knurled portion 79 an intermediate container 82 having a side wall 83 bottom wall 84 and a top wall 85 with a scored portion 86 houses the inner container 75 and a second charge of inhibitor.