60 



THE NATURE AND 

 Log. 60 is - - 1-77815 



and one sixth is 

 constant log. 



Log. 350-2 - 



[SECT. ii. 



0-29636 

 2-24797 



2-54433 



from which subtract 100, and it gives 250 0> 2 for the temperature. Mr. Southern's 

 experiment gives 250 g 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. 



1 Robison's Mechanical Phil. vol. ii. p. 34. " 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. 



