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VIII. On some Physical Properties of Ice ; on the Transposition 

 of Boulders from below to above the Ice ; and on Mammoth- 

 remains. By John Rae, M.D., LL.D., fyc*. 



IS the ice formed on salt water fresh ? or, in other words, if 

 ice formed on the sea is thawed, will the water obtained 

 thereby be fresh ? 



For a number of years past I have spoken with many persons 

 on the above subject; and seldom, if ever, have I found a single 

 individual who did not say that the ice of the sea was fresh. 



Some of these gentlemen are known in the scientific world ; 

 and many of them supported their opinions by quoting the 

 highest written authorities on the subject, chiefly TyndalFs 

 'Forms of Water/ p. 132, par. 339, which tells us that "even 

 when water is saturated with salt, the crystallizing force studi- 

 ously rejects the salt, and devotes itself to the congelation of 

 the water alone. Hence the ice of sea-water, when melted, pro- 

 duces fresh water." 



It is the sentence in italics to which I wish to draw particular 

 attention. 



It would be the extreme of folly and presumption on my 

 part to question the correctness of results obtained by scientific 

 men in their experiments in freezing small quantities of sea- 

 water by artificial means, more especially those of the distin- 

 guished gentleman whose name I have mentioned, who, in 

 addition to holding the high position of being one of our 

 greatest authorities in all that relates to physical science, pos- 

 sesses the rare gift of being able to communicate his knowledge 

 in such plain, clear, and forcible language, illustrated by admi- 

 rable experiments, as to make his meaning fully understood, 

 even by those who had previously been perfectly ignorant of 

 the subject. 



It is only where I have had opportunities of witnessing the 

 action of cold carried on in a manner which may have been 

 denied to the scientific man, that I venture to differ from him ; 

 and it is in this way that the conviction has been forced upon 

 me, that the ice of sea-water if melted does not produce fresh 

 water. 



Before entering upon this subject, however, let me say a word 

 or two on the first part of the quotation I have given. 



If a saturated solution of salt is frozen, and the ice so formed 

 is fresh, it is evident that the salt that has been " rejected " 

 must be deposited or precipitated in a crystalline or some other 

 solid form, because the water, if any, that remains unfrozen, 



* Read before the Physical Society, May 9, 1874. Communicated by 

 the Society. 



