SECT. II.]
PROPERTIES OF STEAM.
69
Ure’s Experiments on the Force of Steam.
Temperature of
steam.
Force in inches of mercury.
Temperature of
steam.
Force in inches of mercury.
Ure’s observa
tions.
By Rule
page 59.
Ure’s observa
tions.
By Rule
page 59.
24°
0-170
0-118
190°
19-000
19-35
32
0-200
0-172
200
23-600
23-71
40
0-250
0-245
210
28-880
28-86
50
0-360
0-37
212
30-000
30-00
55
0-416
0-45
220
35-540
34-92
60
0-516
0-55
225
39-110
38-32
70
0-726
0-78
230
43-100
42-00
80
1-010
1-106
240
51-700
50-24
90
1-360
1-53
250
61-900
59-79
100
1-860
2-08
260
72-300
70-8
110
2-456
2-79
270
86-300
82-45
120
3 300
3-68
280
101-900
97-92
130
4-366
4-81
290
120-150
114-4
140
5-770
6-21
295
129-000
123-5
150
7-53
7-94
300
139-700
133-2
160
9-600
1005
310
161-300
154-5
170
12-050
12-6
312
167-000
159-
180
15-160
15-67
312
165-5
If a nice agreement with a particular set of observations had been attempted,
the formula could have easily been arranged to represent these better; but by so
doing it appears to me that the elastic forces would have increased in a higher
ratio than we are warranted in expecting from other experiments, and the later
inquiries of Mr. Dalton justify the numbers being higher at or about 150° than
Dr. Ure’s.
99. Mr. Southern’s experiments on high pressure steam were made with a
digester, with a thermometer fitted to a metallic tube, so that the stem of the ther
mometer might be immersed as far as it contained mercury. Also, instead of
measuring the force of the steam by a loaded valve, a nicely bored cylinder was
used, with a piston fitting it so as to have very little friction, to the rod of which a
lever was applied, constructed to work on edges like those of a scale beam; and
that no error might arise from this construction, a column of mercury was substi
tuted, and the correspondence was within tvo of an inch.
The observations at each of the points of temperature and pressure were con
tinued some minutes, the temperature being alternately raised and lowered, so
as to make the pressure in excess and defect; and a mean temperature was taken
for the result. This method seems to me entitled to great confidence, and hence
I have made the results the principal data for my formula. (See art. 86.)
The experiments below 212° were conducted nearly as Dr. Robison’s, and those
below 62° were made by Mr. W. Creighton. These low pressure experiments do
not seem to be of equal value with the four high pressure ones.