A simple, rapid test is described that measures contact nucleation of supercooled water. Application of this contact-nucleation test at −3C to over 1000 organic compounds resulted in only 47 that could be considered as “active.” These was a close correlation between the present test and Fukuta's Method b when the samples were in the same physical condition (freshly ground). Materials such as metaldehyde, fluorenone, phenazine and phloroglucinol dihydrate were not found to be sufficiently “active” to pass the contact-nucleation test in an unground state.
It is proposed that the initial water-air interface may pass through a configuration that promotes the growth of ice embryos even though the final compound-water interface has a low “activity,” i.e., a low prewet-nucleation temperature. Conversely, some compounds such as phloroglucinol dihydrate show little “activity” for contact nucleation yet have a high prewet-nucleation temperature.