Expansion of Salt-Solutions. 



391 



I have entered thus minutely into the details of the appa- 

 ratus employed, as it seems to me that it supplies the means 

 of filling up the gap left by the paper of Ramsay and Young* 

 on the attainment of constant temperatures by the employ- 

 ment of liquids boiling under constant pressures; for while it is 

 easy to make a small piece of apparatus air-tight, this becomes 

 well nigh impossible when the apparatus is complicated, and 

 then a simple and efficacious pressure-regulator is a deside- 

 ratum. 



The solutions with which the experiments were carried out 

 were prepared by weighing definite quantities of water, and 

 adding the amount of salt necessary to make a solution con- 

 taining n molecules salt per 100 molecules of water. The 

 solution thus prepared was placed in the vessel shown in fig. 5. 

 This was exhausted of air, placed in a water-bath, and boiled 

 for ten minutes. The vessel was then quickly cooled, and one 

 portion of its contents was transferred to the dilatometer, 

 another to a Sprengel tube, in which its density was deter- 

 mined. The solutions were thus so far deprived of air that 

 no bubbles made their appearance during the experiments. 

 The composition of the solutions, as indicated by the density, 

 was very nearly that indicated by n salt 100H 2 O. A slight 

 error was unavoidable, owing to the necessity for expelling the 

 air. 



Before giving the results of the experiments it will be well 

 to indicate the degree of accuracy obtained. A solution of 

 GNaCl 100H 2 O, gave in two distinct experiments the results 

 given in Table I. The millimetre divisions on the dilatometer- 



Table I. 



t°. 



Volume. 



t°. 



Volume. 



o 



45-2 



101-099 



4°50 



101-093 



50-1 



101339 



508 



101-370 



56-0 



101626 



56-3 



101-640 



615 



101-903 



61-3 



101-898 



67-3 



102-217 



671 



102-211 



723 



102-488 



72-6 



102-502 



78-2 



102-823 



78-1 



102-828 



stems were read roughly to tenths, i. e. to 0*000005, and the 

 temperature to o, l. The degree of accuracy aimed at was 



* Journ. Chem. Society, 1885. 



