FLUIDITY 
749 
TABLE 
OF THE ELASTICITY OF STEAM. 
Temperature. 
— : 
force ot Vap. 
in inches of 
Mercury. 
1 
h 
force ot Vap. 
in inches of 
Mercury. 
Temperature. 
force or Vap. 
in inches of 
Mercury. 
Temperature. 
Force of Vap. 
in inches of 
Mercury. 
Temperature. 
Force of Vap. 
in inches of 
Mercury. 
Temperature. 
Force of Vap. 
in inches of 
Mercury. 
—40° 
.013 
50° 
.375 
106° 
2.25 
162° 
9.91 
217° 
33.09 
273° 
80.98 
—30 
.020 
51 
.388 
107 
2.32 
163 
10.15 
218 
33.72 
274 
82.01 
—20 
.030 
52 
.401 
108 
2.39 
164 
10.41 
219 
34.35 
275 
83.13 
«-10 
.043 
53 
.415 
109 
2.46 
165 
10.68 
220 
34.99 
276 
84.35 
54 
.429 
110 
2.53 
166 
10.96 
221 
277 
85.47 
0 
.064 
55 
.443 
111 
2.60 
167 
11.25 
222 
36.25 
278 
86.50 
] 
.066 
56 
.458 
112 
2.68 
168 
11.54 
223 
36.88 
279 
87.6:1 
2 
.068 
57 
.474 
113 
2.76 
169 
11.83 
224 
37.53 
280 
88.75 
.3 
.071 
58 
.490 
114 
2.84 
170 
12.13 
225 
38.20 
281 
89.87 
4 
.074 
59 
.507 
115 
2.9 2 
171 
12.43 
223 
38.89 
282 
90.99 
5 
.076 
60 
.524 
116 
3.00 
172 
12.73 
227 
39.59 
283 
92.11 
6 
.079 
61 
.542 
117 
3.08 
173 
13.02 
228 
40.30 
284 
93.23 
7 
.082 
62 
.560 
118 
3.16 
174 
13.32 
229 
41.02 
285 
94.35 
8 
.085 
63 
.578 
119 
3.25 
175 
13.62 
230 
41.75 
286 
95.48 
9 
.087 
64 
.597 
120 
2.33 
176 
1 3.92 
231 
42.49 
287 
96.64 
10 
.090 
65 
.616 
121 
3.42 
177 
14.22 
232 
43.24 
288 
97.80 
1 1 
.093 
66 
.685 
122 
3.50 
178 
14.52 
233 
44.00 
289 
98.96 
12 
.096 
67 
.655 
123 
3.59 
179 
14,83 
234 
44.78 
290 
100.12 
13 
.100 
68 
.676 
124 
3.69 
180 
15.15 
235 
45.58 
291 
101.28 
14 
.104 
69 
.693 
125 
3.79 
181 
15.50 
236 
46.39 
292 
102.45 
15 
.108 
70 
.721 
126 
3.89 
182 
. 15.86 
237 
47.20 
293 
103.63 
1G 
.112 
71 
.745 
127 
4.00 
183 
16.23 
238 
48.02 
294 
104.80 
17 
.116 
72 
.770 
128 
4.11 
184 
16.61 
239 
48.84 
295 
105.97 
18 
.120 
73 
.796 
129 
4.22 
185 
17.00 
240 
49.67 
296 
107.14 
19 
.124 
74 
.823 
130 
4.34 
186 
17.40 
241 
50.50 
1 297 
108.31 
20 
.129 
75 
.851 
131 
4.47 
187 
17.80 
242 
51.34 
298 
109.48 
21 
.134 
76 
.8S0 
132 
4,60 
188 
18.20 
243 
52.18 
299 
110.64 
22 
.139 
77 
.910 
133 
4.73 
189 
18.60 
244 
53.03 
300 
111.81 
23 
.1 44 
78 
.940 
134 
4.86 
190 
19.00 
245 
53.88 
301 
112.98 
24 
.150 
79 
.971 
135 
5.00 
191 
19.42 
246 
54.68 
302 
114.15 
25 
.156 
80 
1.00 
136 
5.14 
192 
19.86 
247 
55.54 
S03 
1 1 5.32 
26 
.162 
81 
1.04 
137 
5.29 
193 
^ 20.32 
248 
56.42 
304 
116.50 
27 
.163 
82 
1.07 
138 
5.44 
194 
20.77 
249 
57.31 
305 
117.68 
28 
.174 
83 
1.10 
139 
5.59 
195 
21.22 
250 
58.21 
306 
118.86 
29 
.180 
84 
1.14 
140 
5.74 
196 
21.68 
251 
59.12 
307 
120.03 
30 
.186 
85 
1.17 
141 
5.90 
197 
22.13 
252 
60.05 
308 
121.20 
31 
.193 
86 
1.21 
142 
6.05 
198 
22.69 
253 
61.00 
309 
122.37 
87 
1.24 
143 
6 . 21 
199 
23.16 
254 
6). 92 
310 
123.53 
32 
.200 
88 
1.28 
144 
6.37 
200 
23.64 
255 
62.85 
311 
124.69 
33 
.207 
89 
1.32 
145 
6.5 3 
201 
24.12 
256 
63.76 
312 
125.85 
34 
.214 
90 
1.36 
146 
G.70 
202 
24.61 
257 
64.82 
313 
127.00 
35 
.221 
91 
1.40 
147 
6.87 
203 
25.10 
258 
65.78 
314 
128.15 
36 
.229 
92 
1.44 
148 
7.05 
204 
25.61 
259 
66.75 
315 
129.29 
37 
.237 
93 
1.48 
149 
7.23 
205 
26.13 
260 
67.73 
316 
130.43 
38 
.245 
94 
1.53 
150 
7.42 
206 
26.66 
261 
68.72 
317 
131.57 
39 
.254 
95 
1.58 
151 
7.61 
207 
27.20 
262 
69.72 
318 
132.72 
40 
.263 
96 
1.63 
152 
7.81 
208 
27.74 
263 
70.73 
319 
133.86 
41 
.273 
97 
1.68 
153 
8.01 
209 
28.29 
264 
71.74 
320 
135.00 
42 
.283 
98 
1.74 
154 
8.20 
210 
28.84 
265 
72.76 
321 
136.14 
43 
.294 
99 
1.80 
155 
8.40 
211 
29.41 
2 66 
73.77 
322 
137.28 
44 
.305 
100 
1.86 
156 
8.60 
212 
30.00 
267 
74.79 
323 
138.42 
45 
.316 
101 
1.92 
157 
8.81 
268 
75.80 
324 
139.56 
46 
.328 
102 
1.98 
158 
9.02 
213 
30.60 
269 
76.82 
325 
140.70 
47 
.339 
103 
2.C-1 
159 
9.24 
214 
31.21 
270 
77.85 
48 
.351 
104 
2.11 
ICO 
9.46 
215 
31.83 
271 
78.89 
I 
49 
.363 
105 
2.18 
161 
9.68 
216 
32.46 
272 
79.94 
1 
Mr. Dalton lias discovered that the elas- 
ticity of every other vapour or steam is pre- 
cisely the same, with that of the steam of wa- 
ter at the same distance from its boiling point. 
Thus water boils at 212°; its elasticity at the 
temperature of 182°, or 30 under its boiling 
point, we see from the table is 15.86. Alco- 
hol boils at 176° ; the elasticity of the steam 
of alcohol at 146°, or 30° under its boiling 
point, is likewise 15.86. This very impor- 
tant discovery enables us to ascertain the 
elasticity of tiie vapours of all liquids what- 
ever at "any temperature, provided their boil- 
ing points are known. We have only to find 
how many degrees the temperature at which 
the elasticity required is distant from the 
boiling point of this liquid. The same number 
of degrees, added to or subtracted from 212°, 
gives us a temperature, opposite to which in 
the above table we shall lind the elasticity 
required. 
Such are the phenomena of the conversion 
of liquid into elastic fluids. Dr. Black ap- 
plied his theory of latent heat to this conver- 
sion with great sagacity ; and demonstrated,, 
that it is owing to the very same cause as the 
conversion of solids into liquids ; namely, to 
the combination of a certain dose of caloric 
with the liquid, without any increase of tem- 
perature. The truth of this very important 
point was established by the following expe- 
riments. 
First. When a vessel of water is put upon 
the lire, the water gradually becomes hotter 
till it reaches 212°; but afterwards its tempe- 
rature is not increased. Now caloric must 
be constantly entering from the fire and 
combining' with the water. But as the water 
does not become hotter, the caloric must 
combine with that part of it which flies off in 
the form of steam ; but the temperature of 
the steam is only 212°; therefore the caloric 
combined with it does not increase its tempe- 
rature. We must conclude, then, that the 
change of water to steam is owing to the 
combination of this caloric ; for it produces 
no other change. 
Dr. Black put some water in a tin-plate 
vessel upon a red-hot iron. The water was 
of the temperature 50°; in four minutes it be- 
gan to boil, and in 20 minutes it was all boiled 
off. During the first four minutes it had re- 
ceived 162°, or 40f per minute. If we sup- 
pose that it received as much per minute dur- 
ing the whole process of boiling, the caloric 
which entered into the water and c onverted 
it into steam would amount to 40^ x 20 = 
810°. This caloric is not indicated by the 
thermometer, for the temperature of steam 
is only 212°; therefore Dr. Black called it 
latent heat. 
Second. Water may be heated in a Papin’s- 
digester to 400° without boiling; because 
the steam is forcibly compressed, and pre- 
vented from making its escape. If the mouth 
of the vessel is suddenly opened while things 
are in this state, part of the water rushes out 
in the form of steam, but the greater part still 
remains in the form of water, and its tempe- 
rature instantly sinks to 212°; consequently 
188° of caloric have suddenly disappeared. 
This caloric must have been carried off by 
the steam. Now as only about l-5th of the 
water is converted into steam, that steam 
must contain not only its own 188°, but also 
the 188° lost by each of the other lour parts; 
that is, it must contain 188°x 5, or about 94u°. 
Steam therefore is water combined with at 
least 940° of caloric, the presence of which is 
not indicated by the thermometer. This ex- 
periment was first made by Dr. Black, and. 
afterwards with more precision by Mr. Watt.. 
Third. When hot liquids are put under 
the receiver of an air-pump, and the air is 
suddenly drawn off, the liquids boil, and their 
1 temperature sinks with great rapidity a con- 
siderable number of degrees. Thus water, 
however hot at first, is very soon reduced to* 
the temperature of 70°, and ether becomes 
suddenly so cold, that it freezes water placed 
round the vessel which contains it. In these 
cases the vapour undoubtedly carries off the 
heat of the liquid: but the temperature of the 
vapour is never greater than that of the liquid 
itself ; the heat therefore must combine with 
the vapour, and become latent. 
Fourth. If one part of steam at 2 1 2° is mixed; 
with nine parts by weight of water at 62°, the 
steam instantly assumes the form of water, 
and the temperature after mixture is 178.6°, 
consequently each of the nine parts of water 
has received 116.6° of caloric; of course 
the steam has lost 9 X 1 1 6.6°= 1049. 4° of ca- 
loric. But as the temperature of the steam 
is diminished by 33,3°,. we must subtract this 
