330 Mr Graham oJi the absorptwn of Vapours by Liquids. 



necessarily conjoined and of equal importance, it may be al- 

 lowed us to say, that liquids mvaporate when they take in their 

 vapour, as they are said to evaporate when they give it out. 



The column of boiling points is an index of the invaporat- 

 ing powers of the solutions. The superior invaporating power 

 of chloride of sodium is distinctly connected with the high 

 temperature at which it boils. We see that the power of water 

 to emit vapour at these high temperatures is diminished in va- 

 rious degrees by the saline matter in solution. At low tem- 

 peratures it is probably diminished according to the same rate ; 

 and saline solutions, unable to give out vapour of the tension 

 of that in the atmosphere around them, necessarily become ab- 

 sorbents of that vapour, as is proved by these experiments. 



3. The following tkhle exhibits the weight acquired by solu- 

 tions of the same salt, viz. chloride of sodium, in various pro- 

 portions, and also by sea-water, by enclosure for five days. 

 500 grains of each solution were employed. The boiling 

 points of the solutions are likewise subjoined. 



1. Saturated solution, chloride of sodium, 



2. 2 do. -j_ 1 water, 



3. 2 do. 4- 2 water, 



4. 2 do. -}- 4 water, 



5. Sea-water, 



A capsule of pure water inclosed at the same time, instead 

 of increasing in weight, lost 4 grains. The curious inference 

 is deducible from this experiment, that sea-water is capable of 

 absorbing moisture from air, perfectly saturated with it at the 

 same temperature. The experiment with sea-water was seve- 

 ral times repeated, and it always exhibited a slight invaporat- 

 ing power, while a capsule of pure water placed beside it lost 

 weight. 



4. Several saline solutions and acid liquors were formed, all 

 of which boiled at one temperature, viz. 224°. 700 grains of 

 each were employed, and they were retained for five days in 

 the tin-vessel. In the second column the weight is expressed 



