Triboelectrification of ice

In order to investigate whether the triboriboelectrification of ice is affected by an anisotropic hardness at the surface of specimens or not, the author investigated to the triboelectrification using two kinds of specimens, one is hardened specimen, the other is raw specimen. On rubbing with speed 3.4 cm/s, the hardened specimen is always positively charged as against the raw specimen regardless of the difference of temperature, ananisotropy crystalline plane between the specimens. However, the more fast the rubbing velocity become to, the charging tendency is affected by temperature difference, anisotropy of the crystalline plane owing to soften of the hardened specimen with inceasing by frictional heat.