72 
THE NATURE AND 
[sect. II. 
In the absence therefore of proper experiments to ascertain the force of steam, 
it is difficult to determine a rule that can be depended upon for high temperatures, 
and we must now try to discover if the force of other vapours will afford any 
further insight into the subject. 
Of the elastic Force of the Vapour of Alcohol. 
104. The elastic force of the vapour of alcohol, or spirit of wine, has been 
tried by several philosophers. The greater part of the experiments were made in 
Temperature of 
the steam. 
Elastic force of steam in inches of mercury. 
Dr. Ure’s 
experiments. 
Mr. Ivory’s 
formula. 
Various experiments. 
By our Rule 
page 59. 
32° 
0-2 
0-185 
0-16 
Creighton 
0-172 
50 
0-36 
0-36 
0-37 
70 
0-726 
0-721 
0-78 
90 
1-360 
1-378 
1-53 
110 
2-456 
2-634 
2-79 
130 
4-336 
4-408 
4-81 
150 
7-530 
7-424 
7-94 
170 
12-05 
12-05 
12-60 
190 
19-00 
18-93 
19-35 
210 
28-88 
28-81 
28-86 
230 
43-10 
42-63 
41-51 
Taylor 
42-00 
250 
61-90 
61-50 
60-0 
Southern 
59-79 
270 
86-30 
86-70 
82-5 
Taylor 
83-45 
290 
120-15 
119-9 
114-5 
Taylor 
114-40 
310 
161-30 
162-8 
154-5 
337 
240 
234 
Christian 1 
226-5 
343-6 
264 
240 
Southern 
247-8 
419 
714 
1050 
Clement 
635-0 
432 
1852 
620 
Arsberger 
737-0 
At a temperature of about 770° Mr. Ivory’s formula gives an elastic force equal to the 
modulus of elasticity of water ; the steam would, if this were correct, be more dense than water ; 
while La Tour found it required a space four times its volume to become steam at about the same 
heat. Arsberger’s experiments had not been seen by Mr. Ivory, or he would have had reason 
for doubting the accuracy of M. Clement’s observation ; but as it is quite unsupported either by 
a description of the process, or any observations at other temperatures, its deviation in 
excess both from formulae founded on a considerable range of experiments, and also from other 
results, is to be regarded as a motive for doubt rather than for altering our formula. Mr. Ivory 
most justly remarks, that this furnishes “ another instance of the great difficulty of detecting 
general properties or laws by means of a comparison of particular results and it is a difficulty 
which ought to induce mathematicians possessed of such great powers as Mr. Ivory certainly is, 
to endeavour to develope the first principles, rather than investigate a formula from experiments 
alone. 
1 Mécanique Industrielle, vol. ii. p. 232.