238 LORD RAYLEIGH AND PROFESSOR W. RAMSAY ON ARGON, 
two hours after ‘all absorption of nitrogen had stopped, as well as over red-hot 
copper, copper oxide, soda-lime, and phosphoric anhydride. The gas also passed out 
of the mercury gas-holder through phosphoric anhydride into the weighing globe. 
The results are in complete accordance with previous determinations of density ; and 
for convenience of reference the former numbers are included in the table which 








follows. 
Density of Argon. 
se | | | 
| | | | | Weight of | } 
| Date. Volume. |Remperatntes Pressure. | Weight. | ae pie ee G2 
| | millims. | 
| | 
cub. centims. | 5 | millims. erm. 
(1) Nov. 26. . .| 162°843 15:00 Xda da 8°20) 17784. 19:904 
(2) eee oe 162°843 16-00 Ip 2069,0 9 0:27 cari eel aealeg 19-823 
(C)eDech22 racine 162843 15°62 | 7501 | 026915 | 1°7704 19°816 
(4) Feb. 16... 162843 13:45 | geal Opmsiiey = Ih Tere BY 19:959 
(GD) aie eae eae te 162:843 | 14°47 68:2, Fl NO2789)9 ge ler S42 19-969 
b (Gy) py Zhe te 162°843 17°85 7644 | 027388 | 17810 19-932 

The general mean is 19°900; or if Nos. (2) and (3) be rejected as suspiciously low, 
the mean of the remaining four determinations is 19°941. The molecular weight may 
therefore be taken as 39:9 without appreciable error. 
The value of R in the gas-equation R = pv/T has also been determined between 
— 89° and + 248°. For this purpose, a gas-thermometer was filled with argon, and 
a direct comparison was made with a similar thermometer filled with hydrogen. 
The method of using such a hydrogen-thermometer has already been described by 
Ramsay and Suretps.* For the lowest temperature, the thermometer bulbs were 
immersed in boiling nitrous oxide; for atmospheric temperature, in running water; 
for temperatures near 100° in steam, and for the remaining temperatures, in the 
vapours of chlorobenzene, aniline, and quinolene. 
The results are collected in the following tables :— 
Hyprocen Thermometer. 


Temperature. Pressure. | Volume (corr.). | R. 
| | 
Ce millims. | 
13:04 763°6 1-00036 2°6705 | 
99°84. 992-6 100280 | 26697 
130°62 1073°8 1:00364: 2°6701 
185-46 1218-5 1:00518 2°6716 | 
248-66 1385°1 100705 2°6737 | 
— 87:92 497°3 0:99756 2°6804. | 

QF QQ 
* «Trans. Chem. Soc.,’ vol. 63, pp. 835, 836. It is to be noticed that the value of R is not involved 
in using the hydrogen-thermometer ; its constancy alone is postulated. 
