ON THE MEASUREMENT OF TEMPERATURE. 
14 3 
To measure the temperature of this portion of the stem we employed the device 
Avliich is shown in the figure. A second thermometer similar to the one already 
described, witli a cylindrical hulb (.<! of the same length as the portion of the stem 
he, was mounted opposite the inain thermometer. From the readings of tins 
auxiliary thermometer, taking the temperature of the dead-space and mercury 
column to he the saine in the case of the main thermometer, the mean temperature 
of the stem could be calculated with suflicient accuracy for our purpose. This device 
has already been applied by other investigators to similar measurements. The stem 
of the main and auxiliary thermometers passed at c through a rubber stojjper not 
shown in the figure. A tube rum, terminating in a bulb at the lower end, also 
passed through the ridDber stopper, and communicated with a manometer of the type 
shown in fig. 2, and with an apparatus for generating pure oxygen. 
The volume of the bulb and stem to the point h, of the stem from h to c, and 
of the remainder of the stem and dead-sjDace, were determined l:)y the methods 
described in Part I. of this paper. As in the previous case, the stem was divided 
in millimetres between h and c. 
8. Calibration of the Thermometers. 
Calihraiion of the stem .—The volume of one division of the stem was deterinined 
before the bulb Avas sealed to it, by introducing into it a thread of mercuiy Avhich 
was measured and subsequently weighed. 
Calibration of the dead-space. —The Amlume of the dead-space to the zero point C 
on the stem Avas determined by the method described in Part I. of this pa 2 )er p. (114). 
A capillary stop-cock AA^as sealed to the tube Avhich joined the loAver part of d. 
Mercury AA^as introduced through the stop-cock Ijy means of a rubber tube and 
mercury reservoir, till it Avas l)rought into contact Avith the point. The stop-cock Avas 
then closed, the rulfi)er t\dje removed, and the mercury run out of the apparatus 
and Aveighed. The rubber t\;l:»e Avas then re-attached, and, by raising the reseiwoir. 
mercury Avas introduced so as to fill tlie dead-space and stem to the zero point c on 
the scale. This quantity of mercury Avas Aveighed as betore. 
Volumes of the Bidbs. 
A. 
B. 
C 
I. 
11. 
I. 
II. 
Weight of bulb filled witli 
■water to mark on stem . . 
47 -5376 (10 ■2) 
56 -3542 (21° '8) 
56-3804 (15°-6) 
50 -0494 (19° -3) 
50 -0570 (17° -8) 
AA’’eight of bulb filled with 
water to mark on stem . . 
35 -3322 
30-4265 
30-4253 
23 -3048 
23-3048 
Weight of air in bulb . . . 
0 0147 
0 -0380 
0 -0280 
0 -0289 
0-0289 
„ water in bulb . 
Volume of bulb. 
12-2183 
12-2217 (10°-2) 
25 -9557 
26 -0110 (21°-8) 
25 -9959 
26-0075 (15°-6) 
26 -7157 
26 -7233 
,, atO°C. (Coef. 
of exp. of glass = 0’000028) 
12-218 
25-9948 
25 -9959 
26 -7444 
26 -7456 
