Our “Small Soil Box”, which has a 80 ml (80 cubic centimeter) volume is compatible with 4-Terminal Resistance Meters such as the Miller 400A, the Miller 400D and the Nilsson 400 Resistance Meters.
Miller Soil Boxes can be used to satisfy either the 4-electrode method (ASTM G57 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 0.57cm for the large box. Please see the following link for details: ASTM G57 and AASHTO T-288 Standard Methodologies.
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) sample (A), with the box filled level, divided by the separation between the pins (L) is equal to 1cm.
• Cross-sectional area = 3cm x 2.4cm = 7.2cm2
• Pin separation = 7.2cm
• A/L = 1cm
Soil Box Example: M. C. Miller Factory Tap Water
Measured Resistance = 1.97 kΩ
Resistivity Value = 1.97 kΩ x 1cm
= 1,970 Ω.cm
[Hence, MCM Water Conductivity = 507µS/cm]
