1908] 



on 



Ice and its Natural History. 



251 



more ice, and its volume increases. But the increase of volume is 

 due to the formation of ice out of water, and not to the expansion of 

 a crystalline solid already formed. 



" In Table IX. are given the volumes occupied by the ice (with 

 enclosed brine) formed by freezing 100,000 c.c. (at 0° C.) of a water 

 containing chloride of sodium equivalent to 7 grams chlorine in 

 1,000,000 c.c. (at 0' C). 



Table IX. — Water Containing 7 Parts Chlorine in 1,000,000. 



" The volume {r.,) of the ice and In'ine formed on freezing this 

 water is compared with (P) that observed by Pettersson in freezing a 

 sample of the distilled water in ordinary use in the laboratory. It 

 will be seen that the volumes observed agree very closely with those 

 calculated for a water containing 7 parts of chlorine in a million, on 

 the assumption that the saline matter is contained entirely in adhering 

 liquid brine." 



In the same paper (pp. 1;)5, I'Mi), the very low values found ])y 

 Dr. Pettersson for the latent heat of fusion of ditferent samples of 

 ice prepared l)y freezing sea- water, were quantitatively explained on the 

 basis of the above law ; and the conclusion was experimentally 

 confirmed by the thermal exchanges which were observed to take place 

 in the freezing of a sample of sea-water, as the result of which 

 chemical analysis showed that the ratio CI : 8O3 was the same in the 

 original water, in the ice formed, and in the brine remaining. 



I give these quotations from my papers of 1887 at length because, 

 though published so many years ago, they appear to have been but 

 little read. I know of no manual of physical chemistry in which the 

 above demonstration of the fundamental fact of cryoscopic chemistry 

 is given, nor am I acquainted with any recent treatise on natural ice 

 in which the influence of the nature of the medium, in which it 

 melts, on the melting temperature of ice at constant pressure is even 

 mentioned, still less taken into account. 



For these reasons, in preparing the lecture, I have given the 

 greatest space to this all-important subject, and I proceed with its 

 development. 



