xiv Contents 



PAGE 



steam-tube be chemically clean : Soap is used for this purpose, 

 and the best way of using it is described . . . .160 



The thermometers used and their verification . . .161 



The general order of the experiment 162 



The use of steam for drying the inside of complicated 

 glass apparatus. 



As the result of an experiment, we obtain the temperature 

 of ebullition of the saturated solution and its concentration, 

 also the boiling temperature and the concentration of a series 

 of more dilute solutions . .163 



Determination of the thermal capacity of the apparatus 

 with steam 164 



Thermal specification of the apparatus . . . .165 



Localities where experiments were made . . . .166 



The altitudes above sea-level of these localities are given : 

 they range from 87 metres at Edinburgh to 2733 metres in 

 the Engadine 167 



The salts used in the research 168 



Detailed description of the experiments, the results of 

 which are recorded in Tables II and III . . . .169 



Description of Table IV which contains the greater part 

 of the results of the research 171 



The importance of the physical meaning of the expression 

 W(t-T). 



In the equation W(t- T} = constant, we have Blagden's 

 law of the lowering of the freezing-point of saline solutions 

 extended to the raising of their boiling-points . . .173 



Table V gives the results of experiments made with dilute 

 solutions. 



Exclusion of chloride of rubidium from the Table on 

 account of impurity of the sample. As regards the metallic 

 component it was, as it professed to be, " spectroscopically 

 pure," but it contained sulphate as well as chloride of rubi- 

 dium. This affords a good example of the necessity of testing 

 chemicals which are used in work that is to be published, no 

 matter how great the reputation of the furnisher of the pre- 

 paration may be. 



Table VI is derived from Table V and gives the values of 

 W(t-T) for even temperatures. 



The results given in Table IV in terms of temperature, 

 are repeated in Table VII in terms of the equivalent baro- 

 metric pressure , 



Table VIII gives the vapour tension of water in kilograms 

 per square centimetre at temperatures from 90 C. to 120 C. 



