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IV. — Improved Method of Applying the Micro-spectroscopic Test 

 for Blood-Stains. By Jos. G. Eichardson, M.D., Attending 

 Physician to the Presbyterian Hospital; Microscopist to the 

 Pennsylvania Hospital. 



The value to medical jurisprudence of spectrum analysis as employed 

 for the detection of dried blood is so fully estaljHshed by the re- 

 searches of H. G. Sorby, Dr. W. B. Herepath, Professor A. S. Taylor, 

 W. Preyer, and others, that it seems unnecessary for me to do more 

 than state that the demonstration of the two dark bands in the 

 green caused by scarlet cruorine (haemoglobin), such as that con- 

 tained in a recent blood-stain, enables experts to discriminate 

 positively blood from other red colouring matters soluble in water, 

 whether mineral, vegetable, or animal, except an extract of the red 

 feathers from the Turacus alhocristatus, a bird found in the East 

 Indies, and quite unknown on our continent of America. 



Valuable as this test is thus seen to be, there are, unfortunately, 

 several circumstances which limit its general application, as, for 

 example, the changes in the constitution of haemoglobin which 

 occur from prolonged and frequently from comparatively brief 

 exposure to the air, the modification of the absorption bands caused 

 by the presence of other substances, and last, but not least in many 

 instances, the difficulty of procuring sufficient material for experi- 

 ment. The insuperable nature of this latter obstacle will be at 

 once appreciated when I mention that whilst the smallest amount 

 which Sorby, Herepath, and Taylor furnish directions for testing is 

 a spot " one-tenth of an inch in diameter, or a quantity of the red 

 colouring matter amounting to no more than one thousandth part of 

 a grain," the important stain upon an axe-handle supposed to have 

 been used in a murder I am now investigating probably weighed 

 less than one three-thousandth of a grain when entire and uninjured. 



The exigencies of this case have led me to seek out some other 

 method than that of Mr. Sorby, who recommends that a solution of 

 the suspected colouring matter should be made in a few drops of 

 water contained in a cell composed of a piece of barometer-tube 

 half an inch long and one-seventh of an inch in diameter. Alter 

 numerous experiments, I contrived the following plan, which, on 

 trial, proved satisfactory beyond my most sanguine expectations, 

 enabling me to reveal the presence of blood in a quantity of matter 

 only one one-hundredth the amount directed by Mr. Sorby. 



Procure a glass slide, with a circular excavation in the middle, 

 called by dealers a " concave centre," and moisten it around the edges 

 of the cavity with a small drop of diluted glycerine. Thoroughly 

 clean a thin glass cover about one-eighth of an inch larger than 

 the excavation, lay it on white paper, and upon it place the tiniest 

 visible fragment of a freshly-dried blood-clot (this fragment will 



