( 881 ) 
determined enters the apparatus by the tube s, which is well pro- 
tected from external sources of heat; it passes through the spiral s,; 
consisting of 10 m. of copper tubing of 3.5 mm. bore, doubly wound, 
and is there cooled by the vapour arising from the liquid gas in 
the cryostat: thence it passes to be spiral s,, which is in the liquid 
bath at the experimental temperature ; this spiral is also of 3.5 mm. 
bore, and is 5.3 m. long. The tube 7 leads to a manometer by which 
the expansion pressure of the gas is indicated. From the spiral s,, the gas 
enters the expansion valve, A, tle flow being regulated by the wooden 
pin, p, and, expanding into the vacuum vessel, g, it escapes through 
the wide tube 6,. As before, the vacuum glass, g, is enclosed in a 
german-silver box, 4,, and is protected from radiation from above 
A thermoelement, one junction of which, 7%,, is in the liquid bath, 
and the other, 7h,, in the expansion chamber gives the difference 
between the temperature of the gas before and after expansion. The 
method of insulation has been altered, for the glass tubes (6, and 
6, in fig. 1) gave continual trouble by breaking at inopportune 
moments. In the new apparatus the thermoelement wires, enclosed 
in glass capillaries, are led down through the german-silver tubes 
4, and 6,, from the top of the apparatus. By means of a stirrer, R, 
worked by a string, ¢, passing over a pulley, 4, the liquid bath is 
agitated and the temperature kept constant. Heat conduction to the 
upper portion of the apparatus is minimised by enclosing it in a 
german-silver cylinder, c. 
$ 11. A new series of experiments was made with air at 0° C. 
using this apparatus and the arrangement of fig. 2. 
TABLE VI. 
Series XVIII. Glass valve. Air at 0°C. 15/3/09. 
(p,—1) TT, 
2.29 atm. 0.621°C. 
419, EAR 
5.005, 240 
1463, 4.030 ., 
Bedi 5.136 
Agoda}; 6.410 ,, 
28.09. ,, 7.648 ,, 
28.93 ,, 7.888 ,, 
3406, 8.894 ,, 
37.46 ,, 10.026 ,, 
42.21 „ 11.300 ,, 
