Abstract
By employing several kinds of effective chemical substance, soluble and insoluble, as ice crystal nuclei, the ice crystals were formed in a cold box within which the temperature was comparatively high, i. e. above -20°C, and their plastic replicas were observed through the optical- and the electron-microscope.
The author could not tell the difference of crystal habits according to the various nucleus substances.
Some dodecagonal crystals were found in the plates. As for the size of the nuclei, the smaller nuclei were seen with the lower environment temperature. While the size of AgI-nuclei which were effective above -15°C was larger than the order of 10-5cm, that of most AgIsmoke particles belonged to the order smaller than 10-6cm.
On the one hand, according to almost all the pictures of the plastic replicas of the ice crystals which were formed with the smoke particle nuclei of low solubility such as AgI, Ag2S and PIDI2, their nuclei were seen near the center of the crystals. On the other, regarding the nucleus substance of high solubility such as AgNO3, NaI and NH4I, the existence of the nucleous particles was not recognized in the replicas of the crystals.
