508 URINARY CONCRETIONS. 



or a foreign body secondary calculus-formation. These develop in the bladder 

 itself. 



Primary calculus-formation takes place from free uric acid in the form of 

 sheaves as a nucleus (Fig. 148, 7), and surrounded by layers of calcium oxalate. 

 Secondary calculus- format-ion takes place in neutral urine from calcium carbonate 

 and crystalline calcium phosphate, in alkaline urine from acid ammonium urate, 

 ammonio-magnesium phosphate, and amorphous calcium phosphate. 



Chemical examination next determines whether or not the particles of the 

 concretion are combustible upon a platinum plate. 



I. Combustible concretions can consist only of organic matter. 



(a) If the murexid-test yields a positive reaction, the concretion contains 

 uric acid. Uric-acid calculi are common, often of considerable size, smooth, 

 rather hard, and in color from yellow to reddish brown. 



(b) If another specimen on boiling with potassium hydrate yields an odor 

 of ammonia, and if moist turmeric-paper held in the vapor becomes brown, or a 

 glass rod moistened with hydrochloric acid and held over the vapor yields fumes 

 of ammonium chlorid, the concretion contains ammonium urate. If this test 

 yields a negative result, the concretion contains pure uric acid. Calculi of 

 ammonium urate are rare, generally small, of earthy consistence, and in color 

 between clay- yellow and whitish. 



(c) Should the xanthin-reaction be positive, this substance is present, though 

 it is rare. In one instance, indigo has been found in a calculus. 



(d) If cystin-crystals (Fig. 162, .4) are developed after solution in ammonia 

 and evaporation of the latter, the presence of this rare substance is demonstrated. 



(e) Concretions composed of blood-coagula or fibrinous flakes, without any 

 crystallization whatever, are rare. If burned, they yield an odor of singed 

 hair. They are insoluble in water, alcohol, and ether. They are soluble in potas- 

 sium hydrate, out of which they are reprecipitable by acids. 



(f) Urostealith is the name that has been given to the substance composing 

 rarely found concretions which in the fresh state are soft and elastic, re- 

 sembling India rubber. On drying, they become brittle and hard, and in color 

 between brown and black. Warmth causes them to become softer again, and 

 they melt when heated. Solution takes place in ether, the residue of the evapo- 

 rated ethereal solution becoming violet in color on further heating. Urostealith 

 is dissolved by heated potassium-hydrate solution, with saponification. Concre- 

 tions containing fat or cholesterin are rare. 



II. If concretions are only in part combustible, with a residue, they contain 

 organic and inorganic matters. 



(a) A portion of the calculus is reduced to powder, and this is boiled with 

 water and filtered hot. Urates that may be present undergo solution. In order 

 to determine whether the uric acid is combined with sodium, potassium, calcium, 

 or magnesium, the filtrate is evaporated and fused. The ash is examined spectro- 

 scopically (flame-spectra) , and by this means sodium and potassium are recognized. 

 Magnesium urate and calcium urate are transformed by fusing into carbonates. In 

 order to separate the two, the ash is dissolved in dilute hydrochloric acid, and 

 filtration is practised. The filtrate is neutralized with ammonia; then again dis- 

 solved with a few drops of acetic acid. Addition of ammonium oxalate precipi- 

 tates calcium oxalate. Filtration is now practised, and to the filtrate are added 

 sodium phosphate and ammonia. By this means the magnesia is separated as 

 ammonio-magnesium phosphate. 



(b) Calcium oxalate occurs principally in children, either as small, smooth, 

 pale hempseed-calculi, or in dark, nodular, hard mulberry-calculi. It is not 

 affected by acetic acid, is soluble in mineral acids, without effervescence; and is 

 reprecipitated by ammonia. When fused upon a platinum plate, the specimen 

 becomes black; it is then burned white to calcium carbonate, which undergoes 

 effervescence upon addition of acid. 



(c) Calcium carbonate occurs generally in whitish-gray, earthy, chalk-like, 

 rather rare calculi that usually are multiple. It is soluble in hydrochloric acid with 

 effervescence. . When fused, it becomes at first black, from admixture of mucus; 

 but soon afterward white. 



(d) Ammonio-magnesium phosphate and basic calcium phosphate are usually 

 united in soft, white, chalky stones, which at times attain quite considerable 

 size. Such calculi imply a long sojourn in ammoniacal urine. The first substance 

 yields an odor of ammonia when heated, and more distinctly when heated with 

 potassium hydrate. It is soluble in acetic acid withotit effervescence, and is 

 precipitated in crystalline form from this solution on addition of ammonia. When 



