62 
THE NATURE AND 
[sect. II. 
94. The next point is to compare the formula with experiment; and we shall 
commence with Mr. Watt’s experiments on salt water. The water was nearly 
saturated with salt: it was more free from air than common water, but it parted 
with difficulty from that which it contained. The results compared with the 
formula for saturated salt are shown in the following table. 
Watt’s Experiments on the Steam from Salt Water. 
Temperature. 
Force in inches of mercury. 
Temperature. 
Force in inches of mercury. 
Watt’s observa 
tions. 
Formula for satu 
rated solution. 1 
Watt’s observa 
tions. 
Formula for satu 
rated solution. 1 
46° 
001 
0-24 
195°-5 
15-34 
16-64 
85 
0-58 
1-00 
201-5 
17-16 
18-77 
113 
1-72 
2-33 
207 
19-34 
20-92 
139 
354 
4-66 
210 
21-8 
22-18 
160 
6-27 
7-72 
212 
22-74 
23-05 
169 
8-12 
9-47 
216 
24-6 
24-87 
180 
10-85 
1204 
218 
25-52 
25-84 
187 
12-67 
13-01 
220 
26-5 
26-84 
In these, as in all the early experiments on the force of steam, the force is less 
than it ought to be at low temperatures. 
Mr. Watt’s experiments on pure water afford a like discrepancy, as will be found 
by comparing the following table of results taken at random out of his series. 2 
Watt’s Experiments on Pure Water. 
Temperature. 
Force in inches of mercury. 
Watt’s observa 
tions. 
By our Rule, 
page 59. 
55° 
0-15 
0-45 
118 
2-68 
3-59 
18Ò 
14-73 
15-67 
• 225 
37 
38-32 
240 
49 
50-24 
261 
68 
72-00 
272*5 
82 
86-89 
rated water from the bottom, or lower part of the boiler, by means of a pump, and subsequently by 
means of their blow-off pipes and cocks, now generally followed : the operation of blowing off is 
usually attended to every three or four hours. 
1 The results in this column are calculated by the Rule i, by logarithms, given at page 59, with 
this difference, that instead of subtracting 2-24797 as for common water, the number 2-26703, as 
given in the preceding table, is used for saturated solution. 
2 Robison’s Meehan. Phil. vol. ii. p. 32—34.