Trigger to initiate crystallization

For use in initiating crystallization of a supercooled salt solution, the combination that includes a flexible container containing said solution, and a trigger located in the container in contact with the solution, said trigger comprising

• (a) a thin strip having a perimeter,
• (b) said strip having a multiplicity of generally parallel slits formed therein, each slit characterized as having opposed elongated edges which face one another in near touching relation,
• (c) the strip further characterized as having two configurations between which it is bendable with snap-displacement causing the slit edges to initiate progressive exothermic crystallization of said salt in the solution,
• (d) the strip being in the general form of a dished disc having a central portion and an outer portion surrounding said central portion, the outer portion having a curved periphery,
• (e) said slits confined to said outer portion and said central portion being free of said slits, said slits everywhere spaced inwardly from the disc periphery and located in an annular zone extending about said central portion, the slits defining a sector shaped portion of the annular zone located at a side of said central portion, whereby said periphery is free of slit edges which could otherwise penetrate the container, the container consisting of plastic material,
• (f) the strip consisting of metal and having molecular structure which is impact oriented.