ox THE .MEASHREMEXT OF TEMPERATITRE. 
PART ITT. 
On the Vapour Pressures, of Liquid Hydrogen at Temperatures heloiv its PoiJing- 
Point on the Constant-Volume Hydrogen and Helium Scales. 
Py Morris W. Travers, D.Sc., Fellow of University College, London, 
and Adrien .Ta(,)Tterod, D.Sc. 
Contents. 
1. Previous investigations. . . . . 
2. The liquefaction of hvflrogen. . 
3. The manipulation of liquid hydiogen. 
4. Method of determining the va])oui' i)rcssurcs of li(|uid hydrogeji. 
o. Calculation of the results. 
0. The vapour pressures of lifpiid hydrogen on the constant-volume hydrogen scale 
7. The vapour pressures of liquid hydrogen on the constant-volume helium scale . 
8. Treatment of the results—their probable accuracy .. 
9. Tabulated ^'apour ])ressures of li(pnd hydrogen. 
10. Discussion of the results. 
Appendix L—On the melting-])oint of hydrogen. 
,, IL—On the prepaiation of pure hydrogen. 
,, in. —On the preparation of jmre helium. 
,, IV.—X’ote on the vapour })re.s.sures of solid neon. 
V.—On the probable values of the critical and boiling-points of helium, 
and on an attem])t to liquefy that gas.. . . . . 
Page 
1.55 
157 
158 
158 
1 fil¬ 
led 
164 
167 
169 
169 
170 
171 
171 
175 
176 
I. Prt'Viou.'i In restigi(t ioiis. 
The boiling-point of litittid bydfogen lias Iteen measured directly by Dewar and 
indirectly by (Dlszewske Tbe former enijiloyed constant-volnme hydrogen and 
helium thermometers, tbe latter, howevei', containing a mixture of helium and neon, 
obtained liy a method wlhcli will lie discussed later (p. 171). The results are as 
follows (' Roy. 8oc. Proc.f Feb. 1001, vol. 68, p. 40) :—■ 
Pressure of the 
gas in thermometer 
at OA’. 
Tenqjerature of li(juid 
hydrogen. 
Atmosjjheric 
pressure. 
raillim.^. 
°e. 
milliiiis. 
Hydrogen thermometer («) 
286 ■ 6 
- 253-03 
760-6 
„ „ (h) . 
269-8 
~ 253-37 
764-4 
»» )) ip) 
127-0 
- 250 - .35 
759-5 
„ „ C) ■ • • 
- 739-0 
-252-81 
770-5 
Helium thermometer («) . . 
728-0 
-252-68 
765-0 
» n 0) 
728-0 
- 252-84 
770-0 
X 
