To examine the relative solubility of urate crystals in water, formalin, and ethanol.
Weighed aliquots of synthetic crystals were incubated in each solvent for 72 h at 4 degrees C and were then examined by polarized microscopy.
urate crystals were insoluble in alcohol, sparingly soluble in water, and markedly soluble in formalin.
The marked solubility of urate in formalin is consistent with formation of urate:formaldehyde addition products.