Microbalances per definition resolve to 1 microgram (0.001 milligram). Their use
was for chemical micro-analysis where the weight change of absorption tubes was measured
by weighing them before and after the absorption process. For this reason a relatively
high capacity of typically 20 grams was needed. As was the case with other companies,
most SI microbalances only achieved 0.01 mg resolution. The user was expected to
estimate to 2-3 µg between the graticule divisions. Only the latest models truly
resolved to 1 microgram.
Model MC5 microbalance. Largely identical design as the MC1a, but in grey case. Stanton's
Model MC8 microbalance. A development of the MC5, giving true microgram resolution
by means of an optical vernier. External zero adjustment on l/h side.
The beam of the MC8.
Model MC9 microbalance. Further development led to the MC9. Performance and resolution
as per MC8 but without the use of a rider. This was the culmination of mechanical
microbalance design, in the early 1960's. At that time new analytical methods did
no longer require balances of such high capacity, and in the following decade electronic
balances arrived on the scene.
The beam of the MC9.
A model HP (high-precision) balance with long-range optical projection, note prism
on top of case. Not strictly a microbalance, but achieving the highest possible repeatability
(micrograms or better) at a capacity of a few grams. Used for weight calibrations,
i.e. a mass comparator. Has many features in common with microbalances, hence included
The inner workings of the HP model.
Model HP41 high-precision balance. Much the same as the HP above, but a somewhat
The inner workings of the HP41.
Model MC1 microbalance. 20g capacity, 0.001 mg resolution by optical projection.
Undamped, weight loaded, additional rider.
The beam of the MC1.
The beam of the MC5.
Model MC1a microbalance. 20 g capacity, 0.01 mg resolution by optical projection.
Air-damped, weight loaded, additional rider.