34
U niv ersity
of
O regon M o n t h l y
than the previous weighings. There were a good many very
small water bubbles clinging to the filaments inside the bulb
after it was filled with water, so a correction of 0.25 cc was
made on this account.
Weight of bulb exhausted,
40.51 grams.
Weight of bulb with air
40.69 grams.
Weight of bulb with air and wax, 40.87 grams.
Weight of bulb with gas and wax, 40.765 grams.
Weight of air 0.18 g r.; wax, 0.18 g r.; gas, .075 gr.
Weight of bulb with wax and air, . 40.9 grams.
Weight of bulb with wax and water, 190.65 grams.
Weight of water,
149.75 grams.
With the correction for bubbles this gives 150 cc. as the
volume of air, gas, or water inside the bulb. So 150 cc of air
weighed 0.18 gr. and 150 cc of gas weighed 0.075 gr. There
fore the specific gravity of the air was 0.18-150, and of the
gas 0.075-150 at the pressure and temperature prevailing in
the room. ' It remains to reduce these figures, by means of
the laws of Boyle and Charles, to the corresponding figures
for a pressure of 760 mm. of mercury, and a temperature
of 0 degree, centigrade.
The tables of specific gravity of air were then consulted
and the result was found to agree very closely with the accept
ed figures, the variation being less than one-half per cent.
These figures mean that 13 cu. ft. of water weigh as much
as 10,000 cu. ft. of air.
•J. H. Bond.