60 
THE NATURE AND 
[sect. II. 
Log. 60 is - - 177815 
and one sixth is - 0-29636 
constant log. - 2*24797 
Log. 350-2 - - 2-54433 
from which subtract 100, and it gives 250°*2 for the temperature. Mr. Southern's 
experiment gives 250 o, 3. 
90. When sea water is employed, as it boils at a different temperature, the 
force of the steam is different. The correction in the rules is easily made by find 
ing the constant number which corresponds to a force of thirty inches of mercury, 
at the boiling point, with different degrees of saturation with salt. Many of the 
people employed about boat engines are not yet aware that there is a difference 
between the temperature of steam from common water, and that from salt water, 
when the force is the same. I will show in another place (Sect, iv.) the effect this 
has on the power of the steam engine, but at present our object is to determine the 
force of the steam. Mr. James Watt was the only person who had made experi 
ments on the steam of salt water; they were made in 1774. 1 He does not give 
them as being very accurate ones, but they are sufficient to establish the fact that 
there is a difference ; and Mr. Faraday has lately had occasion to satisfy himself 
on the same point, by various experiments. 2 
91. The following table gives the boiling points of solutions of different salts 
in water. 
Name of salt. 
Dry salt in 100 
parts by weight 
of the solution. 
Boiling point. 
Authority. 
Acetate of soda 
60 
256° 
Griffiths. 3 
Nitrate of soda 
60 
246 
Common salt 
37 
226 
My trials. 
Muriate of soda 
30 
224 
Griffiths. 
Ditto 
222-35 
Achard. 4 
Sulphate of magnesia 
57*5 
222 
Griffiths. 
Sulphate of lime 
45 
220 
Alum 
52 
220 
Sulphate of iron 
64 
216 
Sulphate of soda 
31-5 
213 
Ditto 
217-6 
Achard. 
1 Robison’s Mechanical Phil. vol. ii. p. 34. 2 Quarterly Journal of Science, vol. xiv. p. 440. 
3 Quarterly Journal of Science, vol. xviii. p. 90. 4 Thomson’s Chemistry, vol. ii. p. 14,