XXIV.] URINARY DEPOSITS, ETC. 1 55 



4. Tyrodn ; — Add million's reagent and boil. A red colour in 

 the solution indicates the presence of tyrosin. 



5. Urea: — (i.) Add sodium hypobromite or impure nitric acid 

 (containing HNO2). If no bubbles of gas, no urea is present. If 

 gas given off (2.) remove phosphates and sulphates by addition of 

 baryta mixture and filtration, and remove proteids (see 3.), concen- 

 trate the filtrate if necessary, place a drop on each of two slides, 

 allow one to evaporate slowly under a cover-glass, and to the otlier 

 add a drop of strong pure HNO3 and cover. J^xamine the former 

 for crystals of urea, and the latter for crystals of urea nitrate. For 

 other tests see Lesson XVIII., p. 119). 



6. Uric arid : — If in solution, is in the condition of a urate, 

 (i.) Add a drop of HCl and allow to stand for 24 hours. Examine 

 deposit for crystals of uric acid. (2.) Concentrate original solution 

 (after removal of any proteids present), and apply the murexide 

 test to a small quantity. 



7. Kveatinin : — Add a drop of dilute solution of nitroprusside 

 of sodium and excess of caustic soda. A burgundy-red colour 

 indicates kreatinin. 



8. Ferments : — {a.) Digestive ferments. — Place 5 cc. of the sus- 

 pected fluid in each of four test-tubes. Label these A, B, C, and D. 

 Neutralise the fluid in C and D, if necessary. To A add 5 cc. 

 .4 per cent. HCl and a thread of boiled fibrin, to B 5 cc. of 2 per 

 cent, sodium carbonate solution and a thread of boiled fibrin, to C 

 5 cc. starch solution, and to D 5 or 10 cc. milk. Place the four 

 tubes, along with four control tubes A', B', C, L)' (the contents of 

 which are the same as those of A, B, C, and D, but without the 

 suspected solution) on a water-bath at 40° C. After a time (10 to 

 30 mins.) examine the tubes. Digestion in A, B, or C, or coagula- 

 tion of the milk in D, indicates, if there is no corresponding change 

 in the control tube, the presence of pepsin ^ trypsin, amylolytic 

 ferment or rennin respectively. 



{!>.) Blood ferment. — ^If the solution is suspected to be salted 

 plasma, or if it be oxalate plasma, in the former case dilute with 

 water and place in a water-bath. (Lesson V. 21.) In the latter 

 add calcium chloride (Lesson V. 14), and observe if coagulation 

 occurs. This will also show presence of fibrinogen. 



N.B. — In all cases make a note of what you do, the result 

 thereof, and your inferences. The following form is convenient : — 



Expenment, \ Observation \ Inference, 



