• ( 239 ) 
were always made starting from the homogeneous region towards 
the heterogeneous region. All the measurements were repeated till 
the results differed less than the error of observation, which was 
naturally rather large in these measurements. 
In this way results were reached, which were sufficiently accurate 
for our purpose, as appears from the following comparison of values 
for the change of the plaitpoint temperature with the pressure found 
by us and by van der Lee and Kuenen. 
dt 
dp 
according to 
T. and K. van der Lee 
and Kuenen 
Phenol and water + 0.0033 + 0.004 
Methyl alcohol and hexane + 0.032 + 0.029 
Triethylamine and water + 0.02 + 0.02 
We may state in conclusion that all the measurements- 
carried out by the first mentioned of us (T.). 
6. Results. 
The adjoined table contains a survey of the obtained results. Column 
I gives the examined system, Column II the critical temperatures of 
the components for so far as they are known, Column IV the critical 
end-points (plaitpoint in presence of the third phase); the cases in 
which the three phases exist at higher temperature are indicated by 
an L (lower critical end-point). In column III the values are found 
obtained by other investigators. Column V gives the limits of pressure 
within which the observations were made, column VI the quotient 
which indicates how the plaitpoint temperature varies with an 
d P . X 
increase' of pressure of one atmosphere. Column VII contains special 
remarks and data about the vapour pressure line of the mixture, for 
so far as they are known 1 ), in connection with the above mentioned 
theorem of van der Waals. Column VIII indicates to what type of 
the classification, which will be treated in the next §, the system 
belongs. In connection with this some systems of other investigators, 
which have not been investigated by us, have been inserted in 
the table. 
') A survey of the known maxima in vapour-pressure lines is found in Kuenen, 
loe. cit. p. 129 and in Sydney Young, Fractional Destination. Macmillan and Go, 
London 1903 p. 67. 
