APPENDIX 343 



To distinguish between Nucleo-protein and Mucin. -This is 

 possible only when a large amount of these bodies is present. 

 The acetic acid precipitate is collected on a filter paper, washed 

 with acidulated water, and divided into two portions a and b. 



(a) Boil with 20 per cent. HC1 for 10 minutes ; cool ; neutral- 



ise ; apply Trommer's test. A positive reaction points 

 to mucin. 



(b) Melt in a crucible with fusion mixture ; after the ash 



cools, dissolve it in nitric acid and add molybdate of 

 ammonia solution. A yellow precipitate on warming 

 indicates Nuclein. 



If the Biuret Test gives a Rose Pink Coloration, add a few drops 

 of concentrated pure nitric acid. 



A. A white precipitate, which clears up on warming and 



returns on cooling, points to Froteose. Confirm by the 

 salicyl sulphonic acid test. 



If proteose be present, saturate some of the original 

 fluid, from which native proteins have been separated 

 by boiling with sodium chloride. A precipitate indicates 

 primary proteoses. Filter and add a drop of acetic acid ; 

 a precipitate points to secondary proteoses. 



B. No precipitate with nitric acid, but a distinct pink Biuret 



reaction, points to Peptone. Confirm by saturating the 

 original fluid with ammonium sulphate, filtering and 

 applying the Biuret test to the filtrate. 



When two or more Proteins are present, the following method 

 will be found very useful. 



Add a few drops of salicyl sulphonic acid to several c.c. of the 

 original fluid. A white precipitate may indicate native 

 protein or proteoses. Boil. The proteoses dissolve, 

 whereas the native protein becomes coagulated. Filter 

 hot. If a precipitate forms in the filtrate on cooling it 

 indicates Proteoses. Filter off this precipitate and apply 

 the Biuret test to the filtrate. A rose pink coloration 

 indicates Peptone. 



III. For Fats. In watery solution fat may be dissolved as a soap. 

 The presence of this can be detected by pouring some of the original 

 fluid into about 20 c.c. of 20 per cent. H 2 SO 4 contained in a small 

 beaker, and heated to near boiling point. If soap be present a film of 

 fatty acid will form on the surface of the fluid. 



IV. The following substances should also be tested for. I. Bile 

 salts Pettenkofer's reaction; II. Bile Pigments Gmelin's test. 



V. Urea. (1) Add some fuming nitric acid to some of the original 

 fluid. Effervescence points to urea. 



(2) Repeat with hypobromite solution. 



(3) If 1 and 2 be positive, confirm by obtaining urea nitrate crystals. 

 To do this evaporate about 30 c.c. of the original fluid to small bulk, 

 extract residue with six times its bulk of methylated spirit, evaporate 

 this extract to dryness, dissolve residue in 3-4 c.c. distilled water, and 

 add to the resulting fluid a few c.c. of pure nitric acid, meanwhile 

 keeping the test-tube cool by holding it under the tap. Crystals of 

 urea nitrate separate out if urea is present. Examine under micro- 

 scope. 



