Orgel proposed a novel solution to a problem with Juan Oro's proposed mechanism of nucleobase synthesis on the early Earth, which relied on the reaction of five molecules of hydrogen cyanide (HCN) to form adenine. The problem with this was that it would require much more concentrated hydrogen cyanide than evidence suggested was present.
Orgel suggested that the hydrogen cyanide was frozen in solution. This would concentrate HCN molecules in the spaces in between the crystal lattice of ice, and also solve the problem of HCN being too volatile in a liquid water solution.