CYSTINE. 781 



cystinurics, at least sometimes, such cystine introduced is quantitatively 

 transformed. 1 Cases of cystinuria may occur with or without the 

 occurrence of diamines in the urine, and only rarely are the diamines 

 found in the urine as well as in the feces, which perhaps depends upon 

 the fact, as found by CAMMIDGE and CARROD 2 in one case, that the 

 diamines occur only from time to time in the feces. The properties 

 arid reactions of cystine have been given on pages 147 and 148. 



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 GOLDMAN. 

 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. 



VII. 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. 



As previously mentioned (page 639), the urine of healthy individuals 

 may sometimes, even on voiding, be cloudy on account of the phosphates 

 present, or become so after a little while because of the separation of 

 urates. As a rule, urine just voided is clear, and after cooling shows 



1 See Wolf and Schaffer, Journ. of biol. Chem., 4. 

 2 1. c. footnote 2, page 780. 

 3 Journ. of Physiol., 36. 



