Saturation of Salt-Solutions. 543 



described in a previous paper*, was provided with a cover 

 pierced with holes to hold test-tubes L80 millim. hy 30 millim. 

 Round the top of the bath ran a tube with stopcock* at in- 

 tervals, corresponding to the holes in the cover; this tube was 



connected with the air-blower. The course of experiment 

 was as follows : — Two test-lubes with 50 cubic ceniim. of water 

 in each were taken, and an excess of the same, salt placed in 



each. The contents of one of the tubes were heated till solu- 

 tion was complete, and after partial COOling both tubes were 

 placed in the hath at, say, 12 noon. By means of wide tubes 

 attached to the stopcocks at the side of the bath, a slow 

 Stream of air saturated with water vapour was allowed to 

 bubble up through the solutions in the test-tubes^ which were 

 loosely covered. The whole was left till 10 A.M. Hie next day, 

 when the air-current was turned off, and the solutions were 

 left at rest till 12 o'clock. Jn this way saturation had gone 

 OH in one of the tubes, and crystallization in the other for 24 

 hours. By means of a cork fitted with two tubes, one wide 

 and sufficiently long to reach nearly to the bottom of the test- 

 tube, and covered at the lower end with two-ply of cambric, 

 a portion of the liquid was forced by air-pressure into a 

 Sprengel tube placed in the bath, and another portion collected 

 in a weighed dish. Jn this way the specific gravity and per- 

 centage composition of the solution saturated at 20° C. were 

 found. 



The results were as follows : — 



Tabu IV. 



i°. 



Bait 



1. 



M. V. 



n. 



r 

 n 



o 



20 



NaOl 



1-2011)1 



ao»76 



10-99 



21-2 



M 



KC1 



117777 



2068-79 



8377 



89-f 



I) 



NaN0 3 



1-38608 



2430- J 6 



18-46 



84-2 



)> 



KN0 3 



11 0500 



2092-96 



548 



41-4 



The last eolumn — is the mean molecular volume of each 

 n 



molecule of the salt in a saturated solution. 



Similar experiments were made with the following pairs of 



salts : — 



(I) NaCl + KCl ; (2) NaNOa + NaCl ; 



(3) KCI + KNG3; (4) KNO., + NaN0 3 . 



The results are given in full to show the amount of accuracy 



attained. 



* Phil. Miv/. L883,p, 88ft 



202 



