URINARY CALCULI. 419 



2. Sediment crystalline, or with a characteristic form. 



(a) Triple phosphate (tigs. 282, -283), soluble at once in acids. 



(b) Acid ammonium urate dark yellowish small balls often beset with spines, also 



amorphous (fig. 284). 



(c) Calcium carbonate small whitish balls or biscuit-shaped bodies. Acids dissolve 



them with effervescence (fig. 281). 



(d) Leucin and tyrosin (fig. 272) very rare. 



(e) Neutral calcic phosphate and long plates of tribasic magnesic phosphate (fig. 285). 

 Organised deposits may occur both in alkaline and in acid urine ; pus-cells are more abundant 



in alkaline urine, and so are the lower vegetable organisms. 



272. URINARY CALCULI. Urinary concretions may occur in granules the size of sand, 

 or in masses as large as the fist. According to their size they are spoken, of as sand, gravel, 

 stone, or calculi. They occur in the pelvis of the kidney, ureters, 

 bladder, and sinus prostaticus. 



We may classify them as follows (Ultzmann) : 



1. Calculi, whose nucleus consists of the sedimentary deposits 

 that occur in acid urine (primary formation of calculi). They are 

 all formed in the kidney, and pass into the bladder, where they 

 enlarge by the deposition of mat- 

 ter on their surface. 



2. Calculi, which are either 

 sedimentary forms from alkaline 

 urine, or whose nucleus consists 

 of a foreign body (secondary for- 

 mation of calculi). They are 

 formed in the bladder. 



F . 9fi The primary formation of cal- 



. . , S- "" . culi begins with free uric acid in _, . rig. ^00. 



Acid ammonium urate. the fo * m of sheayes (fig< 256) Basic magnesic phosphate. 



which form a nucleus, with concentric layers of oxalate of lime. The secondary formation 

 occurs in neutral mine by the deposition of calcic carbonate and crystalline calcic phosphate ; 

 in alkaline urine, by the deposition of acid ammonium urate, triple phosphate, and amorphous 

 calcic phosphate. 



Chemical Investigation. Scrape the calculus, burn the scrapings on platinum foil to ascer- 

 tain if they are burned or not. 



I. Combustible concretions can consist only of organic substances. 



(a) Apply the murexide test ( 259, 2), and, if it succeeds, uric acid is present. Uric acid 

 calculi are very common, often of considerable size, smooth, fairly hard, and yellow to reddish- 

 brown in colour. 



(b) If another portion, on being boiled with caustic potash, gives the odour of ammonia (or 

 when the vapour makes damp turmeric paper brown, or if a glass rod dipped in HC1 and held 

 over it gives white fumes of ammonium chloride), the concretion contains ammonium urate. 

 If b gives no result, pure uric acid is present. Calculi of ammonium urate are rare, usually 

 small, of an earthy consistence, i.e., soft and pale yellow or whitish in colour. 



(c) If the xanthin reaction succeeds ( 260), this substance is present (rare). Indigo has been 

 found on one occasion in a calculus (Qrd). 



(d) If, after solution in ammonia, hexagonal plates (fig. 271, A) are found, cystin is present. 



(e) Concretions of coagulated blood or fibrin, without any crystals, are rare. When burned 

 they give the odour of singed hair. They are insoluble in water, alcohol, and ether ; but are 

 soluble in caustic potash, and are precipitated therefrom by acids. 



(/) Urostealith is applied to a caoutchouc-like soft elastic substance, and is very rare. When 

 dry it is brittle and hard, brown or black. When warm it softens, and if more heat be applied 

 it melts. It is soluble in ether, and the residue after evaporation becomes violet on being 

 heated. It is soluble in warm caustic potash, with the formation of a soap. 



II. If the concretions are only partly combustible, thus leaving a residue, they contain 

 organic and inorganic constituents. 



(a) Pulverise a part of the stone, boil it in water, and filter while hot. The urates are dis- 

 solved. To test if the uric acid is united with soda, potash, lime, or magnesia, the filtrate is 

 evaporated and burned. The ash is investigated with the spectroscope ( 14), when the char- 

 acteristic bands of sodium or potash are observed. Magnesic urate and calcic urate are changed 

 into carbonate by burning. To separate them, dissolve the ash in dilute hydrochloric acid, and 

 filter. The filtrate is neutralised with ammonia, and again redissolved by a few drops of acetic 

 acid. The addition of ammonium oxalate precipitates calcic oxalate. Filter, and add to the 

 filtrate sodic phosphate and ammonia, when the magnesia is precipitated as ammonio-magnesic 

 phosphate. 



(b) Calcic oxalate (especially in children, either as small smooth pale stones, or in dark, 



