SECT. II.] 



PROPERTIES OF STEAM. 



61 



92. According to the analysis of Dr. John Murray, 10,000 parts of sea water, 

 of the specific gravity 1-029, 1 contain 



Muriate of soda 220-01 



Sulphate of soda - 33-16 



Muriate of magnesia - 42'08 



Muriate of lime - - 7 -84 = ITTS- 



= 4V 



= TJTJ 



303-09 = A 

 Or 1 part of sea water contains '030309 parts of salts = TJ of its weight. 



93. Now as the salts do not rise with the steam, the water in a boiler supplied 

 with sea water becomes gradually more saturated, and after a certain time begins 

 to deposit salt, if the means that have been invented for that purpose be not 

 employed to prevent it. 2 (See Sect, m.) And even then a certain degree of 

 saturation must be allowed to take place. The following table, with the constant 

 numbers for different degrees of saturation, will serve to illustrate this matter. The 

 boiling point of water appears to be increased one degree by each addition of 2'6 

 parts to the proportion of common salt in 100 parts of water ; at least, so nearly, 

 that this regular law does not materially differ from the mean results of my experi- 

 ments, which were made with a considerable degree of care ; but it is difficult to 

 make them, on account of the degree of saturation constantly varying during the 

 experiment. 



1 Philosophical Magazine. 



2 On the first trip of the City of Edinburgh steam ship to Leith, in 1821, this was found to take 

 place to the detriment of the boiler ; and the deposit was so considerable as to require its being 

 cleared out during the passage, while the vessel proceeded under her canvas. This circumstance 

 led Boulton and Watt, who manufactured the engines, to adopt a method of extracting the satu- 



