On the Freezing-point of Water in Capillary Tubes. 105 



causing the fractures to proceed from its outer surfaces towards 

 it, while the sheet enclosed within the great fracture, from the 

 opposite cause, or an after increase of temperature, was burst 

 completely asunder, its molecules being apparently repelled from 

 its axis, thereby causing the principal rent to proceed along that 

 axis, and many others from it laterally towards the outer sur- 

 faces. Indeed, it is not at all an improbable hypothesis that the 

 much whiter colour of this ice, as noticed by Prof. Erman, may 

 have been due to its complete disruption, to innumerable frac- 

 tures traversing its entire mass, and too minute for detection by 

 the eye. If this were so, then the phsenomenon would be more 

 directly analogous to that of the disruption of the molecules of 

 glass in the case of the Prince Rupert drops, and resulting from 

 the same cause, viz. instantaneous congelation under a reduced 

 temperature. 



The analogy which I have thus briefly attempted to establish 

 between the molecular structure of glass and ice seems to me to 

 be, if successful, a not unimportant step in this inquiry, more 

 especially as regards the principle of a disruptive structure. How 

 far, for example, this principle might elucidate the phsenomena 

 of the veined structure of glacier ice, the white colour of its alter- 

 nate bands, and their more porous character, are questions which 

 will at once occur. Meantime, howevei-, if by leading to further 

 investigation I thereby lead to more luminous results, my object 

 will be attained. 



Greenock, June 14, 1859. 



XIX. On the Freezing-point of Water in Cajnllar]/ Tubes. 

 By H. C. SoRi3Y, F.KS. ^-c* 



UPWARDS of two years ago, when making some experi- 

 ments in order to ascertain the true nature of the liquid 

 contained in the fluid-cavities in quartz, I thought that its 

 freezing-point was well worthy of being determined. Sir Hum- 

 phry Davy had long before shown (Philosophical Transactions, 

 1822, p. 367) that in many cases this fluid was water; and I had 

 myself proved to my own satisfaction that water is given ofi" from 

 the cavities when the crystal containing them is heated so that 

 the expansion of the fluid bursts them ; but I was anxious to 

 confirm this conclusion by some independent experiment, and to 

 prove that it was water whilst still in the cavities. I tliercfore 

 kept for a sufficiently long time a portion of rock-crystal, contain- 

 ing very excellent and distinct fluid-cavities about jlj-^ih. of an 

 inch in diameter, in a mixture of snow and salt at a tcmpcra- 



* Communicated by the Author. 



