THE EFFECT OF LEAD UPON URATE NUCLEATION

Lead urate was crystallized from solutions originally containing 0.595 m M (10 mg%) urate and 0.297 m M PbCl 2 . In the absence of lead, monosodium urate does not nucleate unless the urate concentration exceeds 80 mg%. Lead urate crystals were negatively birefringent and had a distinct x‐ray powder diffraction pattern. Crystals of monosodium urate nucleated on lead urate seed crystals when the urate concentration was 10 mg%. These studies indicate that with physiologic conditions of temperature, pH, and ionic strength, spontaneous nucleation of lead urate can be demonstrated.