SECTION III, 1902 127 Trans. R.S. C. 
XV.— he Variation in the Density of Ice. 
By H. Lester Cooke, B.A., 
Demonstrator in Physics, McGill University, Montreal. 
(Communicated by Professor John Cox, M.A., and read May 27, 1902.) 
In spite of the many accurate researches made with a view to 
obtaining the absolute value of the density of ice, the problem is still 
far from being satisfactorily settled. The determinations made by 
Brunner,! Plücker and Geissler,? Bunsen * and others,‘ leave nothing 
to be desired in point of accuracy, considered singly; yet when com- 
pared with each other, the values obtained by these experimenters 
differ by amounts so far in excess of the probable errors of each 
separate research, that one is forcibly brought to the conclusion that 
there must be some other factor which has been overlooked. 
It was owing to these considerations that Professor Nichols ° was 
led to investigate this problem. One of the primary objects of his 
research was to discover whether this variation in the results obtained 
by previous experimenters was due to constant errors in the methods 
of observation, or was to be ascribed to an actual variation in the 
density itself, the various specimens of ice used in these determinations 
having been obtained under very different conditions. Many inter- 
esting points were brought out in this paper; a variation in the density 
of ice formed under different conditions being unquestionably indi- 
cated; there were also indications that the effect of time on newly 
formed ice was to cause its density to change, apparently approaching 
some normal value. 
Later, some determinations of the density of the St. Lawrence 
River ice were made by Professor H. T. Barnes and the author, in 
order to ascertain what effect age would have on this value. Although 
the age of the specimens experimented with ranged from a few weeks 
to over three years, no variation in density was detected. 
The object of the present paper is to offer a possible explanation 
of this variation. It is evident from the results of the various 
researches, that this variation must obey some very definite laws, 
otherwise much greater inconsistency would be noticed in the form 
of probable errors. 
1 Brunner, Pogg. Ann., Vol. LXIV., p. 113 (1845). 
? Pliicker and Geissler, Pogg. Ann., Vol. LXXXVI., p. 265. 
3 Bunsen, Pogg. Ann., Vol. CXII., p. 1 (1870). 
+ Trans, R/S!) Cy ival Nake) Sec. Tht... p: 155: 
5 E. L. Nichols, Phys. Rev., 8, 21 (1899). 
