For the acetone$(1)-$ diethylamine$(2)$ system the activity coefficients values as

function of concentration are given below

$10\mathrm{.}10\mathrm{.}20\mathrm{.}30\mathrm{.}70\mathrm{.}80\mathrm{.}9$

$11\mathrm{.}11281\mathrm{.}08401\mathrm{.}06171\mathrm{.}00951\mathrm{.}00411\mathrm{.}0009$

$11\mathrm{.}00151\mathrm{.}00611\mathrm{.}01331\mathrm{.}06391\mathrm{.}08121\mathrm{.}1000$

Check the consistency using midpoint method and calculate the van Laar constants.