140 
DK. M. W. TEAVEES, ME. (E SEXTEE, AXD DE. A. JAQUEEOl) 
V is the volume of the bulb to a (fio’. 1), at 0° C. ; is the volume of the dead- 
space and the portion of the stem within the water-jacket; V, is the volume of the 
remaining portion of the stem; a is the coefficient of expansion of glass ; T is the 
temperature to be measured; T/f'^ and are the temperatures of the stem and 
dead-space respectively in degrees Centigrade, The left-hand side of the equation 
irives the value of tlie constant for tlie thermometer. 
o 
The Ice-Point. 
Aolume of bulb at 0° C. 
,, ,, (lead-space. 
,, ,, stem. 
Pressure on gas correcte(i to 0° C. 
Temperature of dead-spaec. 
„ „ stem.■ . 
Constant. 
94-2096 cub. centims. 
0-3904 „ 
0-1031 „ 
987-00 millims. 
11-29° C. 
17-4° C. 
342-2.35. 
The Vapour Pressures of Liquid Oxygeti. 
Volume of luilb at 86-5 abs. 93-8336. 
Pre,ssure on gas 
in thermometer, 
Temperature of 
Temperature 
Vapour pressures 
of 
liipiid oxygen. 
Temperature 
corrected to 
0° C. 
dead-space. 
of stem. 
Found. 
From curve 
(p. 151). 
^ C. 
° C. 
millims. 
abs. 
abs. 
315-17 
11-1 
17-1 
514-5 
85-63 
86-54 
315-26 
11-1 
17-1 
516 
86-66 
86-56 
315-40 
11-1 
17-] 
518-5 
86 - 70 
86-61 
315-59 
11-1 
17-1 
519-5 
86-75 
86-64 
The hgures in the last columns are obtained from tlie smoothed results of tlie 
measurements of tlie vapour pressure of oxygen obtained by means of tlie small 
thermometer. There appears to be a constant difference of 0'L° C. 
In discussing the accuracy of the result it is necessary to })oint out first of all that 
it is extremely difficult to maintain a large mass of liquid air or oxygen in a steady 
state of ebullition ; and for this reason it is probable tliat the results obtained by 
means of the smaller thermometers are the more accurate. In the case of liquid air 
we liave to deal not only with the difficulty whicli arises from tlie superheating of 
the liquid, but, as the liquid evaporates, its temperature rises rapidly. Liquid oxygen 
is not easy to obtain in large quantities, and it is extremely difficult to make 
it boil steadily; it may, in fact, become superheated to the extent of a whole 
decrree Centip'rade. 
