OBSERVATIONS OF OTHER WORKERS
The normal potassium content of the human blood serum has been determined by different workers with various results, as shown in Table 1. The older writers, Schmidt and Wanach, worked with inferior chemical methods. The more recent workers have all obtained fairly uniform results with the exception of Richter-Quittner whose figures are considerably higher than those reported by others. Richter-Quittner found the concentration of potassium in ashed serum to be considerably higher than that found in the ultrafiltrate from the same serum. He argued from this that a portion of the potassium was bound to serum protein. Kramer and Tisdall, however, have foundno discrepancy between the results obtained on ashed serum and those by direct precipitation from the same serum.7 They have emphasized the remarkable constancy of the concentration of potassium in normal human serum.A number of investigators have studied the potassium of the serum in pathologic conditions.