OCCULT BLOOD 187 



Blood in the Urine. The most rapid method of detection is by using the micro- 

 spectroscope. An ordinary hand spectroscope will answer however. 



Donogany's test is very satisfactory. To 10 c.c. of urine add i c.c. ammonium 

 sulphide solution and i c.c. of pyridin. The urine will assume a more or less deep 

 orange color according to its blood content. The spectrum of alkaline methaemo- 

 globin or hgemochromogen will be obtained. See illustrations under urine. 



In making the guaiac or other tests it is a good plan to repeatedly filter the blood- 

 containing urine through the filter. Then touch a spot on the moist filter with the 

 guaiac or benzidin solution and then finally drop on this so treated spot a drop or 

 two of hydrogen peroxide solution. 



Blood in Faeces or Gastric Contents. Take 5 grams of faeces and rub it up 

 thoroughly in a mortar with 15 c.c. of a mixture of equal parts of alcohol, glacial 

 acetic acid and ether. Filter through an unmoistened pleated filter paper re- 

 peatedly until only 3 to 4 c.c. remain of the filtrate. The faeces filtrate can be 

 first tested chemically by depositing a few drops in the center of 3 or 4 circles of 

 white filter-paper placed in a Petri dish or upon an ordinary white plate. 



The moistened spot is then treated with a few drops of a freshly prepared alco- 

 holic solution of guaiac resin (about \ gram of guaiac resin is broken up into 

 small fragments and shaken up in about 3 c.c. of alcohol) and finally there is drop- 

 ped upon the spot a few drops of a solution of hydrogen peroxide. Waves of blue 

 color extending out into the moistened filter-paper show a positive test for blood. 



For the benzidin test pour on this fasces filtrate-moistened filter-paper a few 

 drops of the following solution: 2 c.c. of a saturated alcoholic solution of benzidin 

 2 c.c. of solution of peroxide of hydrogen and two drops of glacial acetic acid. (Blue.) 



If the aloin test is preferred we treat the filtrate-moistened filter-paper with a 

 few drops of a 3% solution of aloin in 70% alcohol and then treating the spot 

 with hydrogen peroxide solution. Brick red colour. 



More reliable is the spectroscopic test. For this we take about 3 c.c. 

 of the concentrated ether, acetic acid, alcohol faecal nitrate and add to it 

 2 c.c. of pyridin. Then add not more than 2 to 3 drops of ammonium 

 sulphide solution. (The ammonium sulphide solution should be kept 

 in an amber-coloied, glass-stoppered bottle. The solution should be 

 freshly prepared every 10 days.) Examine the solution, contained in a 

 small test-tube, with the spectroscope and the two absorption bands of 

 methaemoglobin-alkaline (haemochromogen), between D and E, show 

 a positive blood test. Comparison should be made with fresh blood, 

 in which the absorption band in the yellow is nearer line D 

 (oxyhaemoglobin spectrum). 



