828 URINE. 



only from time to time in the feces. Cystinuria is generally admitted as 

 rather an anomaly in the protein metabolism where the cystine for 

 unknown reasons is not destroyed as ordinarily. It is remarkable 

 that the cystine of the food-proteins is eliminated by the urine, while in 

 cystinurics, at least sometimes, such cystine introduced is quantitatively 

 transformed. 1 Certain observations, such as the appearance of lysine 

 in the urine of cystinurics (ACKERMANN and KUTSCHER 2 ), make it probable 

 that the demolition of other amino-acids is diminished in cystinuria. 

 The properties and reactions of cystine have been given on pages 148 

 and 149. 



Cystine is easily prepared from cystine calculi by dissolving them 

 in alkali carbonate, precipitating the solution with acetic acid, and redis- 

 solving the precipitate in ammonia. The cystine crystallizes on the 

 spontaneous evaporation of the ammonia. The cystine dissolved in 

 the urine is detected, in the absence of proteid and sulphuretted hydrogen, 

 by boiling with alkali and testing with a lead salt or sodium nitroprusside. 

 To isolate cystine from the urine, acidify the urine strongly with acetic 

 acid. The precipitate containing cystine is collected after twenty-four 

 hours and digested with hydrochloric acid, which dissolves the cystine 

 and calcium oxalate, leaving the uric acid undissolved. Filter, supersat- 

 urate the filtrate with ammonium carbonate, and treat the precipitate 

 with ammonia, which dissolves the cystine and leaves the calcium oxalate. 

 Filter again and precipitate with acetic acid. The precipitated cystine 

 is identified by the microscope and the above-mentioned reactions. 

 Cystine as a sediment is identified by the microscope. It must be purified 

 by dissolving in ammonia and precipitating with acetic acid; it is then 

 further tested. Traces of dissolved cystine may be detected by the 

 production of benzoyl-cystine, according to BAUMANN and GOLDMANN. 

 For the detection and estimation of cystine we can proceed to advantage 

 in the following manner, suggested by GASKELL. S The urine freed from 

 oxalates and phosphates by means of ammonia and calcium chloride is 

 treated with an equal volume of acetone and with acetic acid. The 

 crystals which precipitate are dissolved in ammonia and then purified 

 by reprecipitation with acetone. 



VH. URINARY SEDIMENTS AND CALCULI. 



Urinary sediment is the more or less abundant deposit which is found 

 in the urine after standing. This deposit may consist partly of organized 

 and partly^ of non-organized constituents. The first, consisting of cells 

 of various kinds, yeast-fungi, bacteria, spermatozoa, casts, etc., must 

 be investigated by means of the microscope, and the following only 

 applies to the non-organized deposits. 



1 See Wolf and Schaffer, Journ.'of biol. Chem., 4; and Hele, Journ. of Physiol.. 39. 



2 Zeitschr. f. Biol., 57. 



* Journ. of Physiol., 36. 



