These test methods measure the approximate surface
area of precipitated hydrated silicas that is available to the
nitrogen molecule using an approximation of the B.E.T.
method. While the multi-point version of the B.E.T. method is
generally accepted as being less prone to errors arising from
the varying surface properties of individual samples, the
single-point approximation is often adequate due to the shorter
time per test and relative simplicity of the instrumentation
needed. Quality control applications and comparative tests on