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XI. The Tensity and Coefficient of Cvhical Exytansion of Ice. 
By J, H. Vincent, D.Sc., B.A., St. Johns College, Cambridge, 
Communicated by Professor J. J. Thomson, F.R.S, 
Received January 22,—Read February 6, 1902, 
These are perhaps no subjects in the domain of experimental physics which call 
more urgently for attention, than investigations into the properties of water in its 
various states of aggregation. And of the various points which still need studjg 
the latent heat of fusion is without doulit the most pressing. The method whicli 
promises to yield a reliable result for this determination, requires a knowledge of the 
density of ice at 0° C. 
The Bunsen Ice Calorimeter has, in the hands of Dieterici and other Continental 
pliysicists, recently become an instrument of precision, but the results which this 
apparatus is capalde in itself of yielding, are unavailable to Science owing to the 
lack of an accurate knowledge of the density and latent lieat of ice. 
But as Griffiths remarks, “ There can be but little doubt that the mass of 
mercury expelled from a Bunsen Calorimeter by tbe subtraction of a definite tliermal 
unit, is a quantity that can be and doubtless will 1)e determined with accuracy.” 
(Griffiths, ‘ Phil. Trans.,’ A, vol. 186, 1895, p. 265.) It was with the o1)ject of 
contributing something to the solution of tliis proldem that the investigation to lie 
detailed subsequently was undertaken. 
Previous Methods and Residts. 
The first paper of importance, as regards scientific accuracy, on these subjects was 
published by Brunner in 1845 (‘Pogg. Ann.,’ vol. 140, p. 113, 1845), lint liefore 
treating of his paper, we may glance at the state of knowledge on the subject when 
he attacked it. He was led to take up the research by the fact that Petzholht 
(Petzholdt, ‘ Beitriige zur Geognosie von Tyrol,’ 1843) had announced that ice 
expanded when its temperature was lowered. Petzholdt olitained this result 
experimentally, and proceeded to found thereon a new theory of glacier action which 
had the effect of bringing his paper into prominent notice. The idea that ice contracted 
on warming was an old one, and had been originally mooted by Musschenbroek, 
(a 310.) " 13..5.1902 
