Laboratory manual for the detection of poisons and powerful drugsAuthorized translation of the completely rev4th German ed. . est is also apphcable to phosphoratedoils, even though the oil may contain only gram ofphosphorus in 100 grams. But phosphorescence will notappear unless air is admitted into the tube from time to time. Phosphorus in oils cannot be determined quantitatively bythe distillation method, for not more than 36 to 41 per cent, of ^W. Straub, Miinchener medizinische Wochenschrift 50,1145; Archiv derPharmazie 241, 335 (1903); and Zeitschrift fiir anorganische Chemie 35, 4
Laboratory manual for the detection of poisons and powerful drugsAuthorized translation of the completely rev4th German ed. . est is also apphcable to phosphoratedoils, even though the oil may contain only gram ofphosphorus in 100 grams. But phosphorescence will notappear unless air is admitted into the tube from time to time. Phosphorus in oils cannot be determined quantitatively bythe distillation method, for not more than 36 to 41 per cent, of ^W. Straub, Miinchener medizinische Wochenschrift 50,1145; Archiv derPharmazie 241, 335 (1903); and Zeitschrift fiir anorganische Chemie 35, 460(1903)- VOLATILE POISONS 16 phosphorus will distil over. The quantitative method recom-mended by Straub (see page 224) may be used in that case. Detection and Quantitative Estimation of Phosphorus(Mitscherlich-Scherer) Acidify a weighed portion of material with dilute sulphuricacid and add a little ferrous sulphate. Distil in a gentle streamof carbon dioxide, using a large flask fitted with a two-holestopper. Expel air completely from the apparatus by carbondioxide before heating. Use as receiver a flask fitted with a. Fig, 6.—Hilger-Nattermann Apparatus for Detecting and Quantitatively Esti-mating Phosphorus. two-hole Stopper. Pass the end of the condenser through onehole and connect the other with a U-tube containing silvernitrate solution. Evaporate the distillate upon the waterbath with strong bromine water, or with concentrated nitricacid, to oxidize phosphorus or any phosphorous acid the residue in a Httle water and precipitate phos- 16 DETECTION OF POISONS phoric add with magnesia mixture. Weigh the precipitate asmagnesium pyrophosphate, Mg2P207. Heat the contents ofthe U-tube with concentrated nitric acid. Precipitate silveras silver chloride and filter. Concentrate the filtrate by evapo-ration and precipitate phosphoric acid with magnesia mixtureas before. Combine this precipitate with the other. In dis-tillation some phosphorus separates as globule
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