MC Miller’s “Large Soil Box”, which has a 270 ml (270 cubic cm) volume is compatible with 4-Terminal Resistance Meters such as the Miller 400A, the Miller 400D, and the Nilsson 400 Resistance Meters.

Miller’s “Small Soil Box”, has an 80 ml (80 cubic cm) volume and is compatible with 4-Terminal Resistance Meters such as the Miller 400A, the Miller 400D, and the Nilsson 400 Resistance Meters. 

MC Miller Soil Boxes can be used to satisfy either the 4-electrode method (ASTMG57 Standard) or the 2-electrode methods (ASTM G187 or AASHTO T-288 Standards).  For the 2-electrode method, the two interior pins are removed which changes the multiplication factor from 1cm (for the 4-electrode method) to either 0.67cm for the small box or to 0.57 cm for the large box.

Construction Materials:

•  Plexiglas body with rounded corners for easy cleaning.
•  Stainless steel current distribution plates and removable brass pins (potential measurement pins).

Critical Dimensions (for 4-electrode method, i.e. the two interior pins are in use):

The soil boxes are designed such that the cross-sectional area of the soil (or liquid) with the box filled level, divided by the separation between the pins (L) is equal to 1 cm.

•  Cross-sectional area = 4 cm x 3.2 cm = 12.8 cm²
•  Pin separation = 12.8 cm
•  A/L = 1 cm
Soil Box Example:   MC Miller Factory Tap Water

Measured Resistance  = 1.97 kΩ
Resistivity Value           = 1.97kΩx 1 cm

                                     = 1,970 Ω.cm