22 J- SAKURAI. 



the temperature of 100°. Only very slowly did the temperature of 

 the heated magma rise and attained the temperature of about 100° as 

 the mass got almost dry." 



" To this almost dry mass I added 100 gr. of crystallized 

 Glauber's salt, which melted on shaking." 



" The crystalline magma now boiled at even 72°c., whilst the 

 steam indicated 100°c." Qoc. cit., 422). 



It is not correct to say that " the liquid completely boils at 82°, 

 whilst the escaping steam shows the temperature of 100°", for it is 

 only a wet mass of anhydrous sodium sulphate that is heated. I found 

 that steam, in such a case, does not arise from the heated mass 

 uniformly, but escapes through a number of channels produced in 

 those portions of it which are in contîict with the sides of the vessel 

 and which are, therefore, most heated. The central portion of the 

 magma, where the thermometer bulb finds itself, is more slowly 

 heiited, and hence the fact that while the steam indicates the tempera- 

 ture of 100°, the wet magma shows a lower temperature. 



In the second experiment, where some crystallized Glauber's salt 

 is added to the heated magma, the temperature of the latter is, for a time, 

 very much lowered, not only because a quantity of a cold body is 

 introduced, but also because the fusion of the crystallized salt absorbs 

 much lieat. The central portions of the mass, therefore, show as low 

 a temperature as 72°, whilst steam which rapidly forms and escapes 

 along the sides of the vessel shows the temperature of 100°. That 

 the latter does not indicate a higher temperature is easy to understand 

 irom the form of the experiment. It is also needless to mention 

 that the temperature of the whole mass soon rises. 



Gerlach's observations are erroneous, then, in so far as they 

 imply that a substance can evolve a vapour hotter than itself. 



