476 
DR. J. II. YIXCENT OX THE DEXSITY AXD COEFFICTEXT 
Table III. -Biioyancy of Umbrella. 
! Order of 
! AVeighing. 
Circximstances. 
Temperature. 
AVeights 
O 
in grammes. 
1st 
After 15 liours in ice. 
0’ 
5-890 
2iid 
After 21 hours in 1st freezing mixtxu’o. 
- 8" 
6-071 
3rd 
After 33 hours in 1st freezing mixture. 
-4“-4S 
5 - 995 
ttlr 
After 15 hours in 1st freezing mixture. 
r-H 
o 
1 
5-895 
Stli 
After 45 hours in 2nd freezing mixture. 
-9°-42 
G-120 
Gtli 
After 72 liours in 2nil freezing mixture. 
o 
1 
5-910 
Determination of the Density o f Ice at different Temperatures. 
"Uie wire and clamp used in equilibiuting the water and ice were not the same as 
tliose used with the empty imihrella. The values for the buoyancy of the umbrella 
as read from the unbroken straight line on hg. 10 are thus subject to a correction of 
•012 gramme, wliich must be subtracted from the values thus found. The results 
for the huovancv of the undjrella are tluis taken from the broken line in this 
fio'ure. 
Let W = the number of grammes necessary to equilibrate the water at 0° U 
the load in the pan less the corrected buoyancy of the umbrella, 
I = the number of grammes to equililuate the ice at — f U, 
i_t = the density of ice at — f G., 
uq = the density of water at 0°C., 
— the density of mercury at 0° U, 
Ji_f = the density of mercury at — f U 
LC., 
Then equating the two values obtained from the al)Ove for i\[, the mass in grammes 
of tlie material taken; we have 
AI AT 
h,. - M = W and . ],_t - M = T ; 
therefore 
\V = 
I. 
Let 
K = 
tv 
and 
a-n 
u\ 
= <1 > 
then ?_/ 
ffi-t 
K + q ’ 
which was the foi'inula used in computing the results. Since the number K only 
