Analysis of low temperature viscosity data for three NBS standard glasses

The low te mpe r ature viscos iti es of three glasses es tabli shed as. viscosit y sta nd a rds a t th e Nati onal Bureau of Stand ard s are re ported. Th e data overla p res ults which a pp ear on th e published certificates be tween 10" a nd 10" poise and prese nt exte nsive meas ure ments up to 10 '0" poise. The meas ure me nts were made usin g both the fib er-e lo ngation and bea m-be ndin g me thods. No evide nce of an Arrheniu s be hav ior was found for a ny of th e three glasses, even though th e meas ure me nts co vered a na rro w ran ge of te mperatures. An a nalys is of th e inhe re nt meas ure ment unce rtaint y associa ted with each meth od indicates th at th e fiber-elongation meas ure ments are more prec ise th a n the beam-be ndin g meas ureme nts. Ana lys is of th e data a nd its un ce rtai nt y by th e Fulc her Equation supports th e co nc lusions of th e e rror anal ys is.