ppearance of blood stains-Methods of removing blood stains-Microscopical examination-Spectroscopical examination-Other coloured stains.

To say whether suspected spots are blood is frequently a matter hat requires great care and experience in spectroscopic and microscopic examinations. The identification of blood stains not unfrequently furnishes an important link in the chain of evidence in a trial for homicide. It is a common practice when the garments of a suspected murderer are found with red stains on them to attribute the stains to the blood of some domestic animal or bird, or to spots of paint, dye, fruit stains, &c.

Appearance of blood stains.-Blood stains vary very much in size, shape, and colour. If the blood has spurted to a distance from a small artery upon the surface of some nonabsorbent object, the spots present a comet-like shape, terminating in a bulbous tail. The upper portion of the spot is

Appearance of blood stains-Methods of removing blood stains-Microscopical examination-Spectroscopical examination-Other coloured stains.

To say whether suspected spots are blood is frequently a matter that requires great care and experience in spectroscopic and microscopic examinations. The identification of blood stains not unfrequently furnishes an important link in the chain of evidence in a trial for homicide. It is a common practice when the garments of a suspected murderer are found with red stains on them to attribute the stains to the blood of some domestic animal or bird, or to spots of paint, dye, fruit stains, &c.

Appearance of blood stains. Blood stains vary very much in size, shape, and colour. If the blood has spurted to a distance from a small artery upon the surface of some nonabsorbent object, the spots present a comet-like shape, terminating in a bulbous tail. The upper portion of the spot is

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generally of a pale red colour, while to the bulbous extremity the greater portion of the colouring-matter and fibrin has gravitated. Such sprinkling of the blood upon a surface is strongly indicative of its having been ejected from a living body. The colour of a blood stain depends-(i) upon its freshness; if recent, it possesses a bright red colour; if old, the colour is reddish-brown or brownish; (ii) upon its thickness; the thicker a stain the darker its colour; (iii) upon the absorbent nature and colour of the material upon which the blood has fallen; if the material be porous, the colour is dull; if the material be hard and polished, the stains have a shining appearance, provided they are fairly recent. If the stains are on a coloured substance, they are best recognised by artificial light. Before employing any of the tests for blood, a suspected stain should always be examined with a good lens, or with a low power of the microscope. If upon a fabric, the fibres will, in the case of a recent blood stain, present a glossy appearance, and minute clots of blood will be found intermixed with the fibres. If the blood stain be an old one, the fibres will probably appear to be simply stained.

Changes that blood stains undergo by time. If recent, a blood stain is of a red colour, due to hæmoglobin; after a time, which may vary from a very few hours to several days, it assumes a reddish-brown or brownish colour, due to the conversion of the hæmoglobin into methæmoglobin, and finally into hæmatin. These changes of colour are not entirely determined by the age of the stain, but are considerably influenced by the presence or not of impurities in the air. The presence of acid vapours, such as sulphurous, sulphuric, and hydrochloric acids, in the air materially hasten the colourchanges, by effecting the conversion of the hæmoglobin into the brownish acid-hæmatin. This fact is important to bear in mind, as blood stains are liable to change colour much more rapidly in the atmosphere of a manufacturing or other large town than in country air. Hence the conclusion may be drawn, that if the colour of a blood stain be red, the stain is fairly