Abstract
The paper describes experimental techniques found useful in measuring the meniscal resistance of liquids flowing in fine capillaries and narrow channels, dyn cm−1, the Jamin effect.
The resistance has a marginal effect on the accuracy of viscosity measurements in Standard viscometers but with capillaries of lesser bore and in miniature viscometers the resistance can appreciably lower the usually acceptable accuracy while, when the dimensions approach 10 μ, the viscosity results become abnormal especially when emboli are present.
The resistance appears to be associated with thin films adjacent to the menisci; the meniscal resistance of a receding meniscus is usually much greater than the advancing one, due to the viscoelastic properties of the liquid film attached to the meniscus. This film stretches and then breaks causing rhythmic flow of an index of liquid, the flow rate being susceptible to vibrations. The meniscal resistance increases with time of standing and is highly dependent on the nature and condition of the surface.
A chain of liquid indices in a capillary or a pool of liquid between parallel flats has remarkable rheological properties as Jamin, 1860, pointed out.
The presence of macromols in the menisci increases the resistance, especially on standing when cementation of some kind may have occurred as with blood or serum.
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