THE URINARY DEPOSITS are of rare beauty and interest under the microscope. Besides blood, pus, and epithelial cells occurring during grave illness, several crystals are found in ordinary urine with slight variations in health. After standing for a time at a moderate temperature. amorphous granular matter precipitates in most urine, soluble by heat, and composed of the urates of calcium and magnesium with the acid urates of potassium, sodium. and ammonium. These de posits are probably caused by the excess of phos phork acid furnished by the acid sodium biphos phate, which decomposes the alkaline urates. After a longer period, of a few days to two weeks, alkaline fermentation supervenes, due to the presence of yeast fungus and mucus. During this process urea is converted into carbonate of ammonium. As this fermentation begins, the uric acid crystals, occurring as red Tepper dust in the receptacle, begin to dissolve. while adhering to their fragments we find prismatic crystals of orate of sodium and spheroids of orate of am monium. XVIten the alkalinity of the urine is established amorphous granules of phosphate of lime appear, together with triangular prisms of triple phosphates of ammonium and magnesium, and octahedral crystals of oxalate of calcium.
These changes may progress in the pelvis of the kidney or in the bladder. Uric acid gravel or calculus is found in either situation, causing much pain and a grave pathological condition, as the changes in the mucous membrane lining either cavity are important. (See CALcuLus.) Uric acid or urate calculi are generally red and quite hard. Oxalate calculi are usually found, when present, in the pelvis of the kidney, and are of such shape and color as to be called 'mul berry' calculi. Phosphatic calculi are white and soft, and often appear as dust. Calcium car bonate, cyst in, and xanthin calculi are rare. Cal culi may be prevented, and probably phosphatic calculi may be dissolved in the bladder by the use of lithia waters or salicylates. They cause severe inflammatory conditions in most cases. See LITIIIC ACID DIATHESIS; PHOSPHATIC DIA THESIS. See MICROSCOPY, CLINICAL, and accom panying illustrations, Consult Ogden, On the Urine (Philadelphia, 1901).