CHEMICAL AND PHYSICAL NOTES. 113 
lowermost division 0 mm. on the stem, was determined at several 
different temperatures with great care. The result is given in the 
following table :— 
Temperature. Displaced Volume. Dilatation per °C. 
21°°22 C. oe 183° 4271 c.c. a _ 
10°°95 C. : 183°3819 ¢.c. si 0:0045 c.c. 
s°-99 C. . 183-3759 c.c. ai 0:0082 c.c. 
5°°10 C. a 183 °3600|c.c. a 0°0039 e.c. 
11°°05 C. a 183 +3842 c.c. re 0-0059 c¢.c. 
Hence the volume of the body of the hydrometer, when im- 
merged up to 0 mm. on the stem, is 183°3842 c.c. at 11°°05 C., and 
its dilatation per °C. is 0°0039 c.c.; whence we have the volwme of 
body of hydrometer at O° C. = 183-3411 ce. 
As the dilatation is 0°0039 c.c. per °C., we have-— 
Volume of body of hydrometer is 183°3411 ¢.c, at 0° C. 
1835°+3606 3° 
183-3801 10° 
183°3996 15° 
183-4191 20° 
183 °4386 25° 
183° 4581 30° 
A similar table of volumes for every degree can be constructed. 
The constants of hydrometer (1893) No. 16 are therefore— 
Weight of hydrometer in vacuo . » .  . 182°7830 grms. 
Volume of body up to 0 mm. on stem at 0° C. : 183-3411 ce. 
Dilatation per 0° 0. : 0:0039 c.c. 
Average volume of | mm. on stem : iets 0°010437 c.c. 
The volume of the body of the instrument at 15° C. is 183°3996 c.c. 
This is the volume which it displaces when floating exactly at 0 mm. 
on the stem at this temperature. In a liquid of less density, but of 
the same temperature (15° C.), it sinks until all the divided part of 
the stem is immersed, and remains stationary at 100 mm. The 
volume of this liquid which is now displaced is 183°3996 + 1:0437 
= 184-4433 cc. ‘The weight of the hydrometer is the same in both 
cases, namely, 182-7830 grm. Then we have ascertained that at 
15° C. 182-783 grm. of the first liquid have a volume of 183-3996 c.c., 
and that the same weight of the second liquid at the same tempe- 
rature occupies a volume equal to 184°4433 cc. From these figures 
we find the weight of 1 cc. of each liquid at 15° C. to be 
0°996638 grm. for the first or denser liquid, and 0°990998 grm. 
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