Lead Arsenate and Lead Phosphate in Opal Glasses
JSGT 1939 V23 T076-T081
Evidence is given, from X-ray analysis, for concluding that the opacifying substance in a lead glass containing arsenic is lead arsenate, Pb3(AsO4)2, although no direct comparison with a compound of this composition was made. The replacement of arsenic with phosphorus produces an opal glass in which the opacifying substance is lead phosphate, Pb3(PO4)2 In this case, the lead phosphate was identified directly. The crystal structures of the lead arsenate in the opal glass and lead phosphate, and their relations to the structures of some members of the apatite group of minerals are briefly discussed, dimensions of the unit hexagonal cells being determined. For lead arsenate a0 = 10.02 A.U., c0 = 7.37 A.U. The formation of solid solutions between lead phosphate and lead chloro-phosphate is described.
H. P. Rooksby, B.Sc., F.Inst.P.
