1. On repeating the work of Pickering on the
freezing point curves of the amines, the
hydrate of trimethylamine is found to be Me₃N,10H₂O
and not Me₃N,11H₂o. The existence of another
hydrate of diethylamine, possibly Et₂NH,3H₂0, is
2. A method of deducing the degree of hydration
of a solute directly from the conductivities
of its solutions is suggested. While in some cases
the values agree with those from freezing point
data, in others discrepancies are found. The
effect is thus liable to be masked by other
factors, especially at 25°.
3. The degrees of hydration calculated from the
curves obtained where ice is the crystallising
substance agree as well as could be expected with
the criterion that in dilute solution at 0°C each
amine is hydrated to approximately the same extent
as in the first hydrate shown by it in the freezing
point diagram, except in the case of triethylamine.
It appears that the order of hydration in the series,
of methylamines and ethylamines is:
mono < di < tri
when the results from the determinations using the
Beckmann thermometer are considered.
4. When the Beckmann results are corrected for
hydration to the extent indicated, the
positive deviation of the curve given by each amine
from the ideal curve increases as the internal
pressure of the amine decreases. From this
consideration, the degree of hydration of triethylamine
in dilute solution at 0°C is deduced as at
least 12. The order of hydration of the amines
is not the same as the order of basic strength, but
appears to correspond exactly with the order of
internal pressure. The greater the difference
between the internal pressure of an amine and water,
the greater is the degree of hydration.
The results of Moore and Winmill from the
partition coefficient seem to be disproved.