THE
METTLER
PAGE
D E V O T E D TO NEWS A B O U T T R U L Y
MODERN
BALANCES
PRECISION often referred to
as reproducibility... IS THE FOUNDATION on which rests the accuracy of any balance... Friction between moving parts is always present. I t is the friction between knife-edges and planes which is primarily responsible for the dispersion of readings, when the same object is weighed many times on one and the same balance. Precision has been defined as "the degree of
Variable loads on knife-edges give variable
agreement of repeated measurements of the same
friction. Precision becomes a function of the
quantity."
weight to be determined.
The "standard deviation" calculated from the results of such repeated weighings is the measure of the precision of a balance
Constant load on knife-edges gives a constant value to the friction and the precision of the balance does not depend on the weight to be determined.
s=\^f
The precision of a substitution balance working under constant load has a well-defined value. As such, it is a firm foundation for the accuracy of the weighing results.
All METTLER balances are substitution balances working under constant load. The precision of these balances can be, and is, clearly stated in our descriptive literature. Write for your copy today.
METTLER BOX
INSTRUMENT 242,
HIGHTSTOWN. Circle No. 71 on Readers' Service Carl
8 A
·
ANALYTICAL CHEMISTRY
CORPORATION NEW
JERSEY
