Sodium Phosphate Crystals on Salt Fish

SEVERAL times in the past few years, samples of undried or partly dried salt cod with an accumulation of crystals appearing over the surface have been submitted to this laboratory for examination. These deposits did not resemble either the sodium chloride or the calcium sulphate crystals often found on salt fish. One sample had many water-clear rhombic crystals with edges 2 cm. or more long. Others had a second type of crystals: they were dry, powdery white, and thickly scattered over the surface. Curiously, chemical analysis indicated that both types of crystals contained large proportions of phosphate and sodium, a small amount of chloride, but no sulphate, calcium or magnesium.