2S4 ON THE DlELiaiTESCEXCE OP SOUIES. 



metal, than in ^oes not boil so soon in a glass vessel as in one of metal, unlevj 

 glass, unless filings of iron, copper, or some other metal, powdered charcoal, 



this contain i j 



some insoluble o"^ pounded glass, be pat into the former. The difference of 



powder. temperature for water reaches to 1-3° [2'34'' F.] , and sometimes 



This may af- even more. This fact is of the more importance in the gradua- 



atLn of ther- ^'*^" of thermometers, as we may observe a similar difference be- 



monieters, tween two of these insEruments made with equal care, but the 



upper points of which were taken one in a glass, the other in a 



metallic vessel. It is true, that if care be taken not to immerse 



the ball of the thermometer in water, the difference will be less> 



No salt lowers I have found too, that no salt possesses the property of lower- 

 she boiling . , . .,. . ^ . , „, A ; , , 

 point. '"§ ^^^ boiling point of water, though Mr. Acbard has asserted 



the contrary. 

 Degree of the Knowing the boiling point of each solution, by means of 

 whfch^a sTlt^ which we have a measure of the deliquescence of the salt, and 

 wilJ deliquesce of its affinity for water, we may go farther, and ascertain the 

 asicertaina y. (^ggj-gg of the hygrometer at which deliquescence begins to 

 take place. All that is necessary is to place the hygrometer 

 Hinder ajar moistened with the saline solution, and observe the 

 degree it will point out at the expiration of a few hours. Thus 

 it will be found, that with a solution of muriate of soda, satu- 

 rated at 15" [59"], the hygrometer will stop at gO^j with a solu- 

 tion of nitre made at the same temperature, it will stop at 97"^ 

 or thereabout, &c. 

 Muriate of Hence we may conclude, that muriate of soda will not be 



^ ■ deliquescent below 90° of the hygrometer, but will begin to be 



so at this poiwt, and become much more deliquescent beyond it. 

 When a table indicating the degrees of the hygrometer corres- 

 ponding to the boiling point of a certain number of salts is con- 

 structed, we may determine the degree of the hygrometer at 

 which all the others will begin to be deliquescent, as soon as we 

 knov/ the boiling points of their aqueous solutions. 1 need not 

 observe, that what is applicable to deliquescent salts is likewise 

 so to all the solid or liquid bodies that have any affinity for 

 f^ulphuric acid water. On these principles we shall find, that concentrated 

 absorbs more sulphuric acid is capable of taking more than fifteen times its 

 its weipht of weight of water from air completely moist. In setting out 

 water." from this property of various saline solutions having different 



degrees of elasticity at the same temperature, it is easy to deter- 

 mine with precision for every temperature, and every degree 



^ of the 



