61. Chap. 61.-The Nature Of Hail, Snow, Hoar, Mist, Dew; The Forms Of Clouds.

CHAP. 61.—THE NATURE OF HAIL, SNOW, HOAR, MIST, DEW; THE FORMS OF CLOUDS.

I do not find that there is any doubt entertained respecting the following points. (60.) Hail is produced by frozen rain, and snow by the same fluid less firmly concreted, and hoar by frozen dew[1]. During the winter snow falls, but not hail; hail itself falls more frequently during the day than the night, and is more quickly melted than snow. There are no mists either in the summer or during the greatest cold of winter. There is neither dew nor hoar formed during great heat or winds, nor unless the night be serene. Fluids are diminished in bulk by being frozen, and, when the ice is melted, we do not obtain the same quantity of fluid as at first[2].

(61.) The clouds are varied in their colour and figure according as the fire which they contain is in excess or is absorbed by them.

1. Aristotle treats at some length of dew, snow, and hail, in his Meteor. i. cap. 10, 11 & 12 respectively.

2. When water is frozen, its bulk is increased in consequence of its assuming a crystalline structure. Any diminution which may be found to have taken place in the bulk of the fluid, when thawed, must be ascribed to evaporation or to some accidental circumstance.