An examination of Jeffries's magnesium ribbon – potassium oxalate method for the removal of free iron oxide in soils

Jeffries's magnesium ribbon – potassium oxalate method for the removal of free iron oxide from soils has been examined and compared with Beck's modification of the method of Drosdoff and Truog. Iron oxide minerals, whether hydrated or unhydrated, were readily dissolved by the nascent hydrogen – oxalate treatment provided they were in a sufficiently finely divided state. Alumino-silicate clay minerals were not attacked to any appreciable extent, and in general the degree of attack on silicate iron did not appear to be very great. However, biotite was quite seriously attacked by the treatment and relatively large errors could be expected in the estimation of free iron oxide in soils containing much of this mineral. The amounts of silica dissolved from soils by Jeffries's treatment were of the same order as those dissolved by Beck's treatment. The nascent hydrogen method was more efficient than the hydrogen sulphide method, particularly for yellow soils and soils high in free iron oxide.