and on the Organic Bodies contaijied iti Hailstones, S,'C. 169 



found to consist of minute irregular particles, which accounted 

 for the change of colour and opacity. It appears, therefore, 

 as if the molecular action, which causes the solidification, has 

 the power of disaggregating or breaking up the crystalline 

 arrangement of a body in a solid state. 



Exp. 3. A solution of sulphate of soda which is not satu- 

 rated, or has not been allowed to cool entirely, is affected by 

 the contact of a forejgn body much more slowly. After the 

 lapse of several minutes, the formation of separate clusters of 

 crystals much larger than the former is observed : after about 

 half an hour, these clusters were seen at numerous intermediate 

 points throughout the length of the tube, which was several 

 feet long. 



Frost and snow examined under a magnifying power are 

 much more alike than we should expect from their appearance 

 to the naked eye. I have already mentioned the small, nearly 

 cubical prisms, precisely like those of frost, which are found 

 in snow. In the following instance of hoar-frost the likeness 

 is still more complete. 



Dec. 28, 1846. — The ground and all minute filaments were 

 covered with abundant crystals of frost : thermometer 27° F. 

 The filaments of the spider's web were studded with quadri- 

 lateral prisms ranged transversely along the threads. In the 

 afternoon a slight fall of snow occurred, whose particles were 

 exactly like those of Dec. 12, except that they fell in large 

 flakes. These were examined together with other particles of 

 frost deposited on a web, and found to be precisely the same, 

 except that the particles of snow were about a third smaller 

 than those of frost. 



Several salts manifest a peculiar tendency to ascend and cry- 

 stallize on the sides of the vessel which contains them, but none 

 of them so greatly as water when it solidifies in a cavity formed 

 by moist earth. The first crystals formed are considerably 

 above the surface of the water ; and they increase until a solid 

 crust is formed by them and the cavity below remains perfectly 

 dry. Camphor, naphthaline, iodine and hydrosulphate of am- 

 monia, resemble water in their volatile properties, and their 

 tendency to solidify in a crystalline shape. The tendency of 

 the first to deposit itself in crystals on the side of the glass 

 nearest the light is well-known. Naphthaline in the same con- 

 dition slowly deposits a few minute crystals on the same side : 

 after the lapse of a month a few scattered clusters of them were 

 formed, after which no further increase of them was perceived 

 even at the end of several months. Iodine exposed in a large 

 bottle to the sun during the summer formed deposits of differ- 

 ent forms on various occasions, but all composed of rhombic 



P/iil. Mag. S.3. Vol. 30. No. 200. March 1847. N 



