Btl 20 ml. of water had been used. Finally, refluxing was continued for an additional hour.Recovery of Products.'-For the isolation of the reduction products, different procedures were found to be necessary: (a) In those preparations in which the product was soluble in benzene and was isolated as the hydro-

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A potentiometric analyzer, developed to directly measure potassium and sodium concentrations, was evaluated on aqueous solutions, whole blood, serum, and plasma. The analyzer consists of three electrodes—sodium, potassium, and reference—mounted in a flow-cell configuration, and a modified digital pH meter, which displays the ion concentrations directly. Volume of the cell is about 100 µl. The electrodes equilibrate to each new sample in less than a minute. Calibrated with aqueous standard solution, the system yields essentially the same values for whole blood and the corresponding plasma, and results agree with those obtained for the same samples of plasma by flame photometry.

A method has been developed for the polarographic determination of elemental sulfur present in liquefied petroleum gases in concentrations as low as 0.01 p.p.m. Samples of liquefied petroleum gases are collected in specially fitted stainless steel bombs. After volatilization of the sample, elemental sulfur remaining in the sample bomb is dissolved in a pyridine-methanol-hydrochloric acid solvent and the resulting solution electrolyzed polarographically. ELEMENTAL sulfur in petroleum products presents an important problem in the industry because of the ease with which it is formed and its corrosive nature. In contact with most metals, elemental sulfur reacts to form the metal sulfides.The corrosive action of elemental sulfur on mercury, copper, and silver has been used for some time as a semiquantitative test for sulfur in petroleum products (1,6,9). During recent years more accurate quantitative methods have become increasingly important in the development and evaluation of new refinery processes.

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