CN THE DELiaUESCENCE OF BODIES. 233 



with moisture at 15'^ of the centigrade thermometer D^S^ F.] . o-ree in which 

 If it be solid, first make a saturated solution of it in waier at ^ su'^^tance it 

 15" [59" F], and boll the solution*. If it boil at 100' [212^ F.] '^^'•^■^^^=^"^- 

 the boiling point of pure water, the substance is not deliques- 

 cent : but if it do not boil at so low a degree, it is more deli- 

 quescent in proportion as the boiling point rises higher above 

 100°. Thus muriate of soda will be very deliquescent in air 

 saturated with moisture, for its solution in water at 15" {5g" F.] 

 will not boil below 107'4°. [225-32" F.]. Nitre, too, will be 

 deliquescent, but much less than cue preceding salt, as its solu- 

 tion at 15 boils at 101-4" [214-52 F.]. 



Experiment here perfecfly agrees with the theory j but to The theory 

 have a good view of the deliquescence of nitre, and of all sub- gxpeHnieut. 

 stances like it feebly deliquej-cent, they must be taken in small Treatment of 

 separate parcels: in this state they "will be found to dissolve slightly deli- 

 completely, while large crystals would only be covered with a ^tanceT 

 liquid stratum, or would dissolve very slowly. 



It is easy now to perceive how important it is to attend to Importance of 

 the temperature ; for as heat greatly favours the combination of '^ 

 salts with v/ater, the boiling point of each solution will vary 

 according to the temperature at which it is made. Thus nitre, Nitre. 

 which is but slightly deliquescent at 15*, the saturated solution 

 of which boils at 1014, would be greatly so at the temperature 

 of 100° [212°], as the solution saturated at this temperature 

 would boil only at 1 10' or 112° [230° or 233-6" F.] 



Acetate of lead and corrosive sublimate do not perceptibly Salts not dell- 

 5-etard the boiling of water J andaccordingly, they are not at all ^"^''"°'' 

 deliquescent. 



In ascertaining the boiling point of saline or acid liquors, I Liquids boil 



observed a singular phenomenon, that deserves to be made ^^^ ^-"'^^^.'^"^" 



° »^ ' .... peraturein 



known. It consists in this, that water, or any oiher liquid, 



* I .<:hall here observe, that, instead of taking the boiling point of 

 each liquid, it would be more accurate to take the force of iis va- 

 pour at the temperature at which v/e would determine its degree of 

 deliquescence, because the elevation of the boiling point is not pro- 

 portional to the quantity of salt held in solution. Similar means 

 should necessarily be employed to know the force with which solids 

 attract the vapour of w?ter, without any change in their state ensu- 

 ing, as wouli tak« place v/ith lime and salts deprived of their water 

 of crystallization. This subject is treated at length in my original 

 paper. 



, does 



