[BARNES & COOKE] THE DENSITY OF ICE 147 
ranging from 0-91816 to 0-91590; these being given in the following 
table :— 
TABLE I. RESULTS OF NICHOLS ON THE DENSITY OF ICE. 





d Density at0in | 
Kind of Ice Pompe pare terms of that | Means 
Crees of water at 0 
Tcé-mantles ere ur. — 16 0:91619 
(CO:)'and'ether er ere Res — 15 0°91590 0°91615 
— 06 0:91636 
Natural Ice (cicles) nee Eee: — 19 0°91816 
— 16 0°91801 0°91807 
Natural Ice (pond ice newly cut) .. — 07 0°91804 0°91804 
Natural Ice (pond ice one year old) — 18 0°91644 091644 



Nichols then proceeded to compare the results obtained with the 
values given by the other observers for similar specimens of ice and 
showed that there is a remarkably good agreement and one that 
evidently points to real differences in the densities of the specimens, 
and not errors in the methods. 
The importance of these considerations led Nichols to devise 
another and independent method by which these results could be 
checked and verified. The plan decided on was as follows: —A small 
iron box was constructed, built up of slabs of iron with the faces planed 
and polished, with an accurately fitting slab of iron as a cover. After 
having brought the box to the temperature of the room, it was filled 
with mercury, and from the weight of the mercury required to completely 
fill the box, its cubical contents was found. ‘The volume was com- 
puted for zero, by allowing for the cubical expansion of the iron 
and mercury. The box thus having been measured, a piece of ice, newly 
cut from a reservoir, was placed in the box, the ice being of such 
a size as to have a small margin all around it, when in position in 
the box (the insterstices being filled with mercury), the ld, which was 
formed of a planed slab of iron fitting accurately on to the planed 
tops of the four sides of the vessel, was then pressed down, forcing 
out part of the mercury and leaving in the box only mercury and 
ice. From the weight of the ice, determined beforehand, and the 
cubic contents of the box, and the amount of Hg. necessary to fill 
up the space around the ice in the box, the density of the ice could 
be computed. The value obtained was 0-91772. 
Nichols concludes his paper by pointing out the strong evidence 
which his experiments bring to support the theory that there is an 
actual discrepancy between the absolute values of the density of 
