114 
DR. M. \V. TRAVERS, MR. G. SENTER, AXD DR. A. JAQUEROD 
taken to heat only al)out .’1 nhlliins. of the wider tube, so as not to distui’b the 
regularity of its surface at the level at which the inercury meniscus was afterwards 
observed. The operation of sealing the glass point into the 
tube vns not an easy one. 
After Ijending the capillary tube as in the figure, the 
volume of the dead-space was determined in the following 
Jiianner. The wdde tube was cut about 30 millims. below its 
junction with the capillary tube and sealed to a capillary 
stop-cock drawn out to a point at its other end (fig. 5). The 
apparatus w^as fixed in a vertical |)Osition, a ta})-funnel and 
rubl)ei' tube were attached to the stop-cock, and mercury was 
run into the tulje till its surface came exactly into contact 
with the point; the final adiustment was made by closing the 
tap on tlie funnel and compressing the rubber tube with a 
screw-clip. The stop-cock on the dead-space was then closed, 
the rubber tube removed, and the mercury in the dead-space 
run out into a porcelain crucible and weighed. The rubber 
tube was then again attached to the ap])aratus, which was 
next filled with mercury to a mark on the stem. This 
mercury was w^eighed, and from the difference of the two 
w^eighings tlie volume of gas in the dead-space, between a 
mercury meniscus in contact with the point and a mark on the stem, was calculated. 
The experimental results are as follows ;— 
Fig. 5. 
Wight of mercury from stop-cock 
to point. 
Temperature. 
Volume. 
°C. 
'L 34-1522 
20-5 
2-52134 
h. 34-1684 
20-1 
2-5223 ^2-5219 
r. 34-1640 
20-2 
2-5220j 
Weight of mercury from stop-cock 
to mark on stem. 
a. 39 - 3633 
39-3638 
1 20-0 
r 2 - 
9123 
2-9123 
Volume of dead-space to mark on stem . . .< 
2- 
5219 
A- 
3904 
In making an actual experiment, the mercury in the dead-space was brought to 
within a short distance of the point ; this distance was measured by means of the 
telescope and micrometer eye-piece used in measuring the pressure (p. 120). As the 
