OF CUBICAL EXPANSION OF ICE. 
479 
funnel was then levelled. The jar and boxes were filled with ice, and the equilibra¬ 
tion of the water was performed after waiting abt)ut eighteen hours. 
The ice in the boxes was then exchanged for freezing mixture, the glass jar was 
emptied of its ice, and the metal vessel g was filled with freezing mixture and put 
into the jar. After leaving for two days, the ice was equilibrated, and this could lie 
done at difierent temperatures, as the ice very gradually I'ose in temperature. Tlie 
ice could then be examined, or a new equilibration of the water coidd be obtained, by 
allowing the ice to melt and bringing the whole again to 0^ C. 
The results of the difierent equilibrations and the computation of tlie density of ice 
for difierent temperatures below 0° C. are set out in Table IV. 
In this table the letters prefixed to the equilibrations in columns II. and III., 
indicate the order in which these numbers were obtained. In finding the numbers 
in column IX., the values of q is only needed to four significant figures ; l)ut to 
compifie the density of ice at difierent temperatures (column XL) this same (piantity 
q is •0793829. 
The Avhole of the equilibrations performed with the final form of appai'atus are 
given in the table. An improvement of the filler was introduced sidjsequently and 
anomalous results were obtained for the only experiment carried out. This was 
traced to the fact that the wire liad become damaged during the filling, and the 
results for this experiment were rejected. 
In the case of the first experiment tlie water was equilibrated at the beginning 
and end, and the mean value was used for computation. The ice in this ex])erinient 
was not examined. In Experiments 2 and 3, the ice was taken out after the last 
equilibration and was found to be free from milkiness and air bidjldes, but it 
had fine circular cracks running round it concentric with the central stem of the 
umbrella. 
Tlie fourth experiment was conducted differently from the others, and the values 
obtained proved unmistakably that the same specimen of water may assume difierent 
densities on freezing. After the value h had been obtained, the ice was permitted to 
melt either partially or completely. A fresh freezing mixture was put in tlie 
apparatus, and two subsei^uent equilibrations of the new specimen of ice were 
performed. The second specimen of ice had a considerably greater density than the 
first although it was made from identically the same watei'. 
The results given in column IX. are plotted in fig. 12. The points ai'e marked 
with numbers indicating the experiment. The unbroken straight lines drawn through 
the points give u.s, Ijy extra-polation, four values for the density of ice at 0° C., while 
a broken line drawn parallel to the straight line for Expeiiment 2 through the point 
given by the first specimen of ice in Experiment 4 furnishes a fifth value. The 
numbers thus obtained and tlie weights to be assigned to them in computing the 
mean are set out in Table V., the weight assigned in each case being equal to the 
number of equilibrations of the ice. 
