In the paper by Kaelbling, R.; Craig, J. B., and Pasamanick, B. on "Urinary Porphobilinogen" published in the Archives of November, 1961, in Table 1, on page 496, the correct proportions for the method in which the Watson-Schwartz test was performed should read: 5 ml. urine
+5 ml. Ehrlich's aldehyde
+10 ml. saturated sodium acetate
The amount of Ehrlich's aldehyde was erroneously reported as 10 ml. in the original paper.