546 OXIDATION FERMENTS 



The author has endeavored to perfect a method which 

 shall make use of the great sensitiveness of the peroxidase 

 reactions but be free of those sources of error which are 

 inherent to the older form of these tests and which have 

 brought their forensic value into question. This object has 

 been attained by combining a test described by Leers 23 with 

 Adler's leukomalachite-green test. Leers prepares a 

 haematin extract by treating the object supposed to be con- 

 taminated with blood with a concentrated alcoholic solution 

 of caustic potash. The haematin is dissolved out by shaking 

 the solution well with pyridin, is then reduced by a reducing 

 agent to hsemochromogen and examined spectroscopically 

 for final detection. The author at first proceeds in the same 

 way as Leers ; but then the pyridin solution charged with 

 the blood coloring matter in a small separating funnel is 

 transferred to a filter paper spread out on a glass plate and 

 a hydrogen peroxide solution of leukomalachite base in dilute 

 acetic acid is added. The presence of haematin is shown by 

 an intense green color. 24 In this procedure the sources of 

 error occasioned by the true peroxidases (as of pus, nasal 

 mucus, milk and vegetable tissue) are excluded by previous 

 boiling with concentrated caustic potash. Moreover, the 

 disturbing features caused by inorganic catalysators need 

 not be taken into consideration as, even though they are not 

 thrown out (as is iron) by the potash in the form of inac- 

 tive hydroxides, they will not dissolve in the pyridin solu- 

 tion. Material for testing, consisting of a few strands of a 

 blood-soaked fabric, or blood stains on wood or iron imple- 

 ments may be successfully and with certainty identified, even 

 if they had been previously boiled in water. The author be- 

 lieves that this method, which can be carried through in a 

 very short while without special apparatus, may be relied 

 upon to fairly answer the requirements of practice. 



23 Leers, 1. c., pp. 64-65, and Table ii, Fig. 2. 



24 For details of the process consult 0. v. Fiirth, Zeitschr. f . angew. Chem., 

 24, 1625, 1911. 



