H 



John White 



The formula deduced from these '\^ Pb<C^ j^ .^^KCiHiOi. 



The hig-h value for potassium is probably due to incom- 

 plete washing, leaving a slight excess of potassium acetate 

 adhering to the crystals. When heated in a vacuum oven the 

 salt suffered no appreciable loss in weight and exhibited only 

 a very slight change in color, even after long-continued heat- 

 ing. When heated in a melting tube, it showed no change 

 up to 205 °C., when there were signs of sintering and it turned 

 very slightly yellow. At 208-208. 5 °C. it melted fairly sharp 

 to a pale straw-colored liquid ; this solidified to a white crystal- 

 line mass on cooling, which again gave the same melting point, 

 showing that no decomposition had taken place. 



From the mother liquor, after removal of the potassium 

 salt, upon evaporaton, there was obtained long needle-like 

 crystals which were white, but readily turn slightly yellow on 

 standing. This salt has the appearance and properties of 

 the double potassium lead iodid described by Remsen and 

 Herty^ and by Wells. ^ No particular attempt was made to 

 purify these ; an iodin estimation gave 54.30 per cent iodin, 

 while KPhI^.2H.,0 requires 57.46 per cent iodin. 



The Ammonium Salt. — This was prepared in the same way 

 as the sodium salt, except that the reaction was found to work 

 better if no acetic acid is added. The ammonium compound 

 is so insoluble that it generally precipitates from the boiling 



^Amer. Chem.Jour., XI, 296; Ibid, XIV, 107. 



'K4mer. Jour. Sci., XLV, February No. (1803); Studies from the Chem- 

 ical Laboratory of Sheffield Scientific School, Yale University, vol. I, 250. 



320 



