As interpolation and spline-interpolation usually generate awes which
do not preserve monotonicity or convexity, some problems in natural sc
iences and engineering cannot: be solved by these methods in a satisfa
ctory way. These difficulties are shown by means of a subject of satur
ation in adsorption. Two algorithms will be presented which produce co
-monotone C-1- and C-2-curves. They are constructed with aid of the Be
rnstein-operator. It is shown that co-monotone C-1-splines solve the a
bove problem. A disadvantage of C-2-splines is discussed. The reasons
for the properties of this kind of interpolation are given.