bn :016) Melting and boiling point of minerals II. S 
. 
d 
3 
LER 
ERT 3 
This simple expression states that the ratios between 
the boiling points of fluids, on the absolute scale of tem- 
E perature, are the same at all pressures. The formula (3) may 
with minute accuracy be applied to a number of related 
substances. For most other substances c is a very small 
factor and higher values are chiefly obtained only for associa- 
ted fluids such as water, the alcohols and oxy-acids, which 
are exceptional even in many other respects. 
The formula (3) is very simple and can be applied in 
calculating the boiling point of a substance at a given pressure 
even if the boiling point of this substance is known at one 
pressure only. These circumstances point to the fact that 
formula (3) is advantageous in geological speculations. From 
this point of view it seems indicated to investigate its 
degree of accuracy. 
In order to make a survey of the behaviour of different 
fluids with regard to the variations of their boiling points with 
changes in pressure the author compared them with a stand- 
ard substance. To this standard chlorine, which is carefully 
investigated by K nietsch?2), was selected. 
The comparison was made in the following manner: in 
the first place the boiling points of chlorine, which correspond 
to the pressures under which the fluid in question has been 
investigated (TAL), were interpolated from Knietschs 
values. Thereupon a theoretical boiling point was calculated 
with the aid of formula (3), where T.,= the boiling point 
of chlorine under the pressure in question, To, = the boiling 
point of chlorine at 1 atmosphere (= 239”.4 absolute), T; = 
the boiling point of the fluid at 1 atmosphere while T,' = 
the boiling point to be calculated. 
Pad Gp re rel Na 
PES EA ROP 
12 Knietsch. Annalen der Physik 259. 124. 1890. 
