[BARNES & COOKE] THE DENSITY OF ICE 153 
operations. The cover was then securely bolted on, the end of the 
suspension passing up through the tubular opening, and after having 
completely covered the main body of this inner vessel to a depth 
of about 10 to 15 ems., the whole apparatus was carried in to the 
laboratory and placed under the table on which the balance was 
placed. After passing the suspension up through the table and 
balance case, it was attached to the arm of the balance and the 
vessels beneath adjusted till it was hanging freely. Before taking 
the weight, the specimen was allowed to remain thus suspended for 
about 15 minutes so as to accurately assume the temperature of the 
surrounding mixture. After the weight had been carefully taken 
to -1 of a milligram, the water was allowed to enter the inner vessel 
from the surrounding mixture and the weight again taken. The density 
of the ice is calculated from the loss of weight owing to the immersion 
in the water. 
The weight and density of the suspension had to be allowed for 
in these calculations, and they were determined in the same manner 
as the ice density, the experiment being carefully repeated on the 
suspension and grip after each ice density experiment, and using the 
same water for immersion. The density of the water in the inner 
vessel was then compared with that of distilled water by means of a 
pyknometer. All the weighings were corrected to weight in vacuum. 
One of the primary objects of these experiments was to deter- 
mine the variation in the density of old and new ice in case any such 
difference existed, and with this end in view, the specimens exper- 
imented upon were cut from blocks of ice taken from the St. 
Lawrence River during the winters of 799, 00, and *01, and kindly 
supplied to us by Mr. Becket, from the warehouses of the City Ice 
Company. However, no systematic difference was noticed in these 
three kinds of ice, and it is safe to assume that for ice similar in 
formation <o these (1.e., formed on the lower surface of a thick field 
of ice completely covering the river), no such variation exists. 
Nichols’ experiments, however, clearly showed that on the specimens 
used in his determinations age certainly acted in such a manner as 
to cause the density to continuaHy approach the value which he 
assumes as the normal. 
Sec. III., 1902. 10. 
