urate

Rarely, sodium urate occurs in crystalline form—slender prisms, arranged in fan- or sheaf-like structures (Fig. 32).

It is possible—as in urate infarcts of infants—for urates to be molded into cylindric bodies within the renal tubules.

The sediment usually contains abundant amorphous phosphates and crystals of triple phosphate and ammonium urate.

Compare the terrestrial octopus, which makes armor-plating out of calcium urate instead of excreting urea or uric acid.

Now dissolve the pure urate by washing it through the filter with a few cubic centimeters of the special nitric acid.