238 PHYSIOLOGICAL CHEMISTRY 



the phenolphthalein reagent 1 and a few drops of hydrogen peroxide. A pink or 

 red color promptly forms in the presence of blood. 



Schirokauer 2 makes the statement that a mixture of alcohol and glacial acetic 

 acid will give the phenolphthalein reaction for occult blood. The action of an oxi- 

 dizing agent will make this reaction more distinct. Von Czylharz and Neustadl 3 

 find that a solution of sodium salicylate added to a blood-free extract of feces will 

 give a very deceptive reaction, while feces after the administration of sodium 

 salicylate by mouth gave the same reaction. The same was true of acetyl salicylic 

 acid and other similar drugs. Their studies in clinical cases likewise indicated that 

 the phenolphthalein test was unreliable. 



(e) Hematein Reaction for Occult Blood. Couturi er 4 advises the use of 

 hematein 5 in testing for occult blood. It is only slightly soluble in water, 

 but gives a pronounced red color. In contact with sodium hydroxide 

 this red solution turns a deep violet blue, giving an insoluble compound 

 of hematein and sodium. This compound, exposed to the air oxidizes 

 after several days, and gives brownish or yellowish compounds, depend- 

 ing on dilution. This change is only hastened a little by the addition 

 of hydrogen peroxide, but if a trace of blood is added to the hydrogen 

 peroxide, it takes place almost instantly. To avoid oxidation, the hem- 

 atein sodium mixture should be prepared just before use. Three fluids 

 are required: (i) a 0.05 per cent aqueous solution of hematein; (2) a 

 40 per cent solution of sodium hydroxide and (3) 3 per cent hydrogen 

 peroxide. These will keep almost indefinitely. *^"" 



The test may be perf ormed as follows : Take 4-5 c.c. of the liquid specimen in a 

 tube and in another tube take the same amount of material known not to contain 

 blood as a control. To each add 4-5 c.c. of the sodium hydroxide solution and 

 shake. Then to each of the tubes add 2 drops of the hematein solution. A blue 

 color of about equal intensity will develop in both tubes. Then add 10 drops of 

 hydrogen peroxide to each tube and compare. If blood is present, the tube con- 

 taining it will turn very rapidly (in three or four seconds) to violet red, then in 

 twenty seconds to clear brown, in forty seconds to pale yellow while the second 

 tube will not show these changes for several minutes. The reaction is said to 

 detect blood when present in a concentration of i part in 400,000. 



(f ) Cowie's Guaiac Test. To i gram of moist feces add 4-5 c.c. of glacial ace- 

 tic acid and extract the mixture with 30 c.c. of ether. To 1-2 c.c. of the extract 

 add an equal volume of water, agitate the mixture, introduce a few granules of 

 powdered guaiac resin, and after bringing the resin into solution, gradually add 

 30 drops df old turpentine or hydrogen peroxide. A blue cplor indicates the 



1 Prepared by dissolving 1-2 grams of phenolphthalein and 25 grams of KOH in 100 c.c. 

 of distilled water. Add i gram of powdered zinc and heat gently until the solution is 

 decolorized. Prepared in this way the solution will not deteriorate on standing. 



2 Deutsch. med. Woch., Aug. 6, 1914. 



1 Wien. med. Woch.^ Sept. 5, 1914. 



4 Lyon Med., 46, 313, 1914. 



6 Hematein is a brownish-red crystalline substance derived from hematoxylin by the 

 successive action of ammonia and acetic acid. It should not be confused with hematin, 

 the hemoglobin derivative. 



