or of alkyl phenyl phosphite, respectively. Methods applicable to phosphorus and nitrogen [Kolb et al. (94K) and ] and two methods applicable to phosphorus and sulfur [Patterson (136K) and Patterson and Howe (137K)] are described in the sulfur and nitrogen portions of this review.The determination of arsenic in catalytic reformer feedstocks by flameless atomic adsorption published by La Villa and Queraud (103K) involves adding 5 mL of 1% iodine in toluene, extracting twice with 10 mL of 1% nitric acid, evaporating the extract to dryness, adding 2 mL of 1% nitric acid, running the sample in the spectrometer, and comparing the results with those for a blank and for standard solutions of arsenic and magnesium. Michelot (114K) determined silicon in coking naphthas contaminated with siloxane antifoam agents by using a direct reading emission spectrometer equipped with a graphite rotating-disk electrode; the naphtha is diluted with mineral oil sufficient to reduce the combustion rate but not to affect the sensitivity.