Experimental procedure for the determination of phosphorus in aluminium alloys

2 EXPERIMENTAL PROCEDURE FOR THE DETERMINATION OF PHOSPHORUS IN ALUMINIUM ALLOYS (9) 

The samples were cylindrical disks (15 or 20 inn diameter, 1 inn thick). The standard was pure aluminium powder (Erba, e.g.) mixed with disodium hydro-genphosphate (Mallinckrodt, e.g.). Disodium hydrogenphosphate was dried for 2 h at 150°C and finely ground in a mortar. The mixture that contained 

9 % of phosphorus was shaken for 3 d. From this mixture pellets with 

The composition of the disodium hydrogenphosphate after drying was verified gravimetrically by precipitation as ammonium molybdophosphate. It contained (99.5 + 0,3) % of the expected phosphorus content. 

The homogeneity of the standard mixture was also carefully checked. In 

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