SECT. II.]
PROPERTIES OF STEAM.
79
with the least range of temperature above the one convenient for condensation : to
a vapour of this kind, heat may be applied without requiring so extensive a surface
for the fire to act on as when water is used.
On the other part, a fluid which has a low elastic force at a high temperature
may sometimes be conveniently and safely applied to afford a regular heat to the
acting vapour ; hence, it becomes difficult to say to what objects it is improper to
extend our inquiries.
Mr. Dalton made some experiments on the vapour of ammonia. The ammonia
he used boiled at 140° ; and its specific gravity was *9474. It had a force of 4’3
inches at 60° ; but on increasing the temperature, the volatile parts separated first,
and left the rest with a greater proportion of water, requiring a still higher tem
perature to convert them into steam : this fluid is therefore inapplicable.
113. The force of the vapours of petroleum, and of oil of turpentine, has been
ascertained by Dr. Ure : the following tables contain his results :—
Experiments on the Force of Vapour of Petroleum, 1 or Naphtha.
Force in inches of mercury.
Force in inches of mercury.
Temperature.
Ure’s experi
ments.
Formula.
Temperature.
Ure’s experi
ments.
Formula.
316°
3000
30 00
350°
46-86
48-1
320
31-70
31-8
355
50-20
325
34-00
34-1
360
53-30
54-8
330
36-40
36-6
365
56-90
335
38-90
370
60-70
62-4
340
41-60
42-
372
61-90
345
44-10
375
64-00
66-5
Experiments on the Force of the Vapour of Oil of Turpentine. 2
Force in inches of mercury.
Force in inches of mercury.
Temperature.
Ure’s experi
ments.
Formula.
Temperature.
Ure’s experi
ments.
Formula.
304°
30-00
30-00
340°
47-30
50-10
307-6
32-60
31-6
343
49-40
52-5
310
33-50
32-7
347
51-70
315
35-20
35-3
350
53-80
57-3
320
37-06
38-0
354
56 60
322
37-80
39-0
357
58-70
326
40-20
41-1
360
60-80
65-4
330
42-10
43-6
362
62-40
336
45-00
.
1 For tlie steam of petroleum, the boiling point being 316°, the rule in logarithms is
log. / = 6 (log. (t + 100) - 2-37291).
2 For the steam of oil of turpentine, which boils in a tube at 304°, the rule in logarithms is
log./ = 6 (log. t + 100) — 2-36019 )•