REPORT ON THE SPECIFIC GRAVITY OF OCEAN WATER, 
3 
0’865 c.c. Both series of observations show that the stem is uniform, so that we take 
the volume of 1 mm. to be 0'00865 c.c. 
When this operation of calibration was finished, the end of the stem was carefully 
closed before the blow-pipe. 
Table I. 
Showing the Values obtained in Two Preliminary Trials of the Hydrometer. 
First Series. 
Second Series. 
Load. 
Gramme. 
Stem. 
Millimetres. 
Differences. 
Stem. 
Millimetres. 
Differences. 
o-o 
98 
12-8 
98-9 
11-9 
o-l 
85-2 
11-4 
87-0 
11-9 
0-2 
73-8 
11-5 
75-1 
11-1 
0-3 
62-3 
. 11-3 
64-0 
11-0 
0-4 
51-0 
11-5 
53-0 
12-2 
0-5 
39-5 
11-5 
40-8 
11-2 
0-6 
28-0 
10-8 
29-6 
11-7 
0-7 
17-2 
11-4 
17-9 
11-7 
0-8 
5-8 
6-2 
0-85 
-0-2 
Mean 
J • • • 
11-525 
11-587 
The hydrometer was now carefully weighed on one of Oertling’s best balances with 
the following result : — 
Weight in air, ........ 160-0405 
Add for air displaced by hydrometer, .... 0T968 
Less buoyancy of weights, ..... 0-0245 
0-1723 
Weight in vacuo, ....... 160-212S grms. 
When the hydrometer floats in a liquid, then the true weight of the volume of liquid 
displaced is equal to the weight in vacuo of the hydrometer, less the weight of the 
