BLOOD AND BLOOD COLORING MATTERS 753 



tion of these and the active oxygen taken up by the guaiaconic acid 

 which is oxidized to guaiac blue (guaiaconic acid ozonide). Urine con- 

 taining pus, even when no blood is present, gives a blue color with these 

 reagents; but in this case the tincture of guaiac alone, without tur- 

 pentine, is colored blue by the urine (VITALI J ). This is at least true 

 for a tincture that has been exposed for some time to the action of air 

 and sunlight. The blue color .produced by pus differs from that pro- 

 duced by blood -coloring matters by disappearing on heating the urine 

 to boiling. A urine alkaline by decomposition must first be made faintly 

 acid before performing the reaction. The turpentine shouid be kepr, 

 exposed to sunlight, while the tincture of guaiac must be kept in a 

 dark glass bottle. These reagents to be of use must be controlled by a 

 liquid containing blood. With positive results, however, this test is 

 not absolutely decisive, because other bodies may give a similar reaction, 

 but when properly performed it is so extremely delicate that when it 

 gives negative results any other test for blood is superfluous. 2 



HELLER-TEICHMAXN'S Test. If a neutral or faintly acid urine con- 

 taining blood is heated to boiling, one always obtains a mottled pre- 

 cipitate consisting of proteid and haBmatin. If caustic soda is added 

 to the boiling hot test, the liquid becomes clear and turns green when 

 examined in thin layers (due to hffimatin alkali), and a red precipitate, 

 appearing green by reflected light, re-forms, consisting of earthy phos- 

 phates and haBmatin. This reaction is called HELLER'S blood-test. If 

 this precipitate is after a time collected on a small filter, it may be used 

 for the hffimin test (see page 286). If the precipitate contains only a 

 little blood-coloring matter with a larger quantity of earthy phosphates, 

 then wash it with dilute acetic acid, which dissolves the earthy phosphates, 

 and use the residue for the preparation of TEICHMANN'S h^min crystals. 

 If, on the contrary, the amount of phosphates is very small, then first 

 add a little MgCl 2 solution to the urine, heat to boiling, and add simulta- 

 neously with the caustic potash some sodium-phosphate solution. In 

 the presence of only very small quantities of blood, first make the urine 

 very faintly alkaline with ammonia, add tannic acid, acidify with acetic 

 acid, and use this precipitate in the preparation of the ha3min crystals 

 (STRUVE 3 ) . 



O. and R. ABLER 4 have recommended leucomalachite green or benzidine in 

 the presence of peroxide arid acetic acid as especially sensitive reagents for blood, 



Haematoporphyrin. Since the occurrence of haBinatoporphyrin in the 

 urine in various diseases has been made very probable by several investi- 

 gators, such as NEUSSER, STOKVIS, MACMUNN, LE NOBEL, COPEMAN, and 

 others, 5 SALKOWSKI has positively shown the presence of this pigment 



1 See Maly's Jahresber., 18. 



2 For more details in regard to the preparation of the reagents and the performance 

 of the reaction see O. Schumm, Zeitschr. f. physiol. Chem., 50. 



3 Zeitschr. f. anal. Chem., 11. 



4 Zeitschr. f. physiol. Chem., 41. 



5 A very complete index of the literature on haBmatoporphyrin in the urine may be 

 found in R. Zoja, Su qualche pigmento di alcune urine, etc., in Arch. Ital. di. clin. 

 Med., 1893. 



