Two spectrographic methOds are used in mobile field laboratories of the U. S. Geological Survey. In the direct-current arc method, the ground sample is mixed with graphite powder, packed into an electrode crater, and burned to completion. Thirty elements are determined. In the spark method, the sample, ground to pass a 150-mesh screen, is digested in h y r o fluor i c acid followed by evaporation to dryness and dissolution in aqua regia. The solution is fed into the spark gap by means of a rotating-disk electrode arrangement and is excited with an alternating-current spark discharge. Fourteen elements are determ1ned. In both techniques, light is recorded on Spectrum Analysis No. 1, 35-millimeter film, and the spectra are compared visually with those of standard films.

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An 18-year-old female patient receiving adjuvant chemotherapy for osteogenic sarcoma developed a pruritic erythematous rash during infusion of the eighth dose of methotrexate (8 g/m2) in the series. In other respects, the infusion proceeded normally but the 24-hour serum concentration of methotrexate was unexpectedly and extremely high, 574 mumols/L. Dosing error was excluded, as was the hypothesis that the high concentrations were due to the presence of methotrexate-specific antibodies. Acute oliguria and renal failure were the primary manifestations of the drug-induced toxicity and the high concentrations can be attributed to decreased renal elimination of the drug over the first 24 hours. Treatment consisted of folinic acid rescue, forced diuresis, sequential charcoal haemoperfusion and haemodialysis, and repeated oral doses of activated charcoal. After examination of the contribution of the extracorporeal procedures and the charcoal to the elimination of the drug, the relative lack of morbidity was attributed primarily to the folinic acid rescue and the intensive supportive care.