microscope, blood may be readily detected by the presence of the characteristic blood-cells; but even this means of diagnosis may be rendered useless, by 1. The blood being long effused.

2. The spot being wetted and then dried.

3. The blood being mixed with other substances. 4. The spot on the cloth being much rubbed, or the cloth washed.

c. Action of Water.-Water has a wonderfully solvent action on blood, the stains rapidly dissolving when the material on which they occur is placed in cold water—a bright red solution being formed. Rust is not soluble in water.

d. Action of Heat.-Blood-stains on knives, etc., may be readily removed by heating the metal, when the blood will peel off, at once distinguishing it from rust. Should, however, the blood-stain on the metal be long exposed to air, spots of rust may be mixed with the blood, when the test will fail. The solution obtained in water is coagulated by heat, the colour entirely destroyed, and a flocculent muddy brown precipitate formed.

e. Action of Caustic Potash.-The solution of the blood obtained in water is boiled, when a coagulum is formed, soluble in hot caustic potash; the solution formed being greenish by transmitted, and red by reflected light.

f. Action of Nitric Acid.-Nitric acid added to a portion of the watery solution produces a whitish grey precipitate.

g. Action of Guaiacum.-Tincture of guaiacum produces in the watery solution a reddish-white precipitate of the resin; but on the addition of an etheral solution of peroxide of hydrogen, a beautiful blue colour is developed. Other red colouring matters give a reddish colour to the precipitated resin, but the blue colour does not appear when treated as above.

h. Hamin Crystals.-These are produced by treating

a drop of blood, or a watery solution of it, with glacial acetic acid in a watch glass, and then evaporating the mixture. The dried residue now contains the crystals of hæmin, which may then be examined under the microscope. The crystals are rhomboidal in form, tubular, or otherwise,' of a yellowish, yellowish-red, or dirty blood-red colour. When the stain is old, a small quantity of table-salt should be added to the acetic acid solution of the colouring matter of the blood.

i. Spectroscopic Appearances.-Two dark absorption bands appear situated at the junction of the yellow with the green rays, and in the middle of the green rays of the spectrum. The spectrum of alkanet root in solution of alum is like that of recent blood, but differs in having a third absorption band between the green and the blue. This test requires care and considerable practice at spectrum analysis.

There is no means of detecting menstrual blood from human blood the result of a wound.

Points of Importance to be noticed in the Examination of a Person found wounded.

a. Note situation, extent, depth, breadth, length, and direction of wound.

b. Is there any appearance of ecchymosis, or is the effused blood liquid or coagulated?

c. Examine wound as to presence of pus, adhesive inflammation, gangrene, or foreign bodies.

Why? Presence of pus, etc., will show that death must have taken place some time after the wound was inflicted.

d. In all examinations of wounds, be careful to disturb as little as possible their outward appearance, in order to compare the wound with the suspected weapon.

e. All notes should be taken during such examination, or immediately after.

f. Make a careful examination of all the important organs of the body.

Why? In order to disprove the suggestion that death was due to other causes- -poison, disease, etc. g. Only facts should be stated in the report; no inferences should be drawn or suggested.

h. In describing the appearance of wounds, use simple, untechnical language, and avoid superlatives and high-flown words to describe and explain simple facts.

i. In gunshot wounds, note position of body, state and contents of the hands, and the direction of the wound in relation to external objects.

CONCUSSION OF THE BRAIN, ETC.

Concussion of the brain may arise from falls on the nates, or from blows on the head.

Symptoms. The face becomes pale, the pupils contracted, the pulse weak and small, the respiration scarcely perceptible, and the sphincters relaxed. Reaction succeeds; the pulse quickens, the skin is hot and dry, there is great confusion of thought, and vomiting is present in most cases. Concussion often

It

passes into compression, due to hæmorrhage from lacerated cerebral vessels. Great care is required in forming a prognosis with regard to the ultimate effect of an injury to the head. Inflammation of the brain and membranes may be delayed for some weeks. is often a difficult matter to distinguish the effects of concussion from those common to drunkenness or narcotic poisoning. The odour of the breath and the history of the case will assist in forming an opinion.

BURNS AND SCALDS.

A burn is caused by the direct action of flame, or the application of any highly heated substance to the

surface of the body. A scald is due to the action of boiling water or other fluid on the body. Burns sometimes present little more than a slight redness of the skin, which may pass off in a few days; at other times blisters are formed, the base of the blister being red, with a narrow red line round it. Burns may result from only a slight application of heat, due probably to the thinness of the skin in some individuals. Often troublesome ulcers are formed, or the skin may be charred. On the same person, the appearance of each burn may be different. The danger from burns depends more on the extent of surface injured than on the intensity of the burn. Burns of a half or third part of the body must be regarded as fatal. They may prove fatal by shock, by asphyxia, or by constant and profuse discharge from the burnt surface. Children are most obnoxious to burns and scalds, the simplest often proving fatal. Persons have often been murdered and then burnt in order to conceal the crime.

Was the burn inflicted before or after death ?-Two characteristic appearances redness and vesicationare present in burns inflicted during life, when the surface of the body is not charred and the tissues destroyed. The redness affects the surface and entire substance of the true skin, which is dotted by the deep red openings of the sudoriferous and sebaceous ducts. Blisters are formed by a temperature somewhat less than that of boiling water.

In burns produced after death, the surface and substance of the true skin is of a dull white colour, dotted with grey openings of the sudoriferous and sebaceous ducts, and the subcutaneous tissues are uninjected. It may be necessary to distinguish the vesicles due to a burn, from the phlyctanæ, the result of advanced putrefaction. The vesications produced by a burn have a purple red line at their circumference, and a more or less red base. Bulla, the result of putrefaction, possess none of these characteristics. Their base

does not differ in colour from that in the immediate neighbourhood of the vesicle. It appears possible to produce vesication by the application of intense heat after death; but these vesicles possess none of the appearances of vital reaction. The bullæ thus produced soon burst, and never contain serum, but only a thin watery vapour. The redness of the base, and the red bounding line round their circumference, so characteristic of burns inflicted before death, are also absent.

Was the burning homicidal, suicidal, or accidental?_ No general rules for guidance can be here laid down. In most cases, the conditions under which the body is found, will point less to suicide than to homicide or accident. In cases of murder, the body is often burnt to destroy all traces of the crime. The conjunction of robbery will greatly assist in helping to solve the difficulty.

The possibility of 'spontaneous combustion' is too absurd to be more than noticed here.

CONTUSIONS, BRUISES, ETC.

These injuries are accompanied with swelling and more or less discoloration of the part affected. They might be confounded with sprains or with scurvy. From a sprain they are distinguished by pain in the joint, and the history of the case. From scurvy, by the condition of the gums-common to that diseaseand by the state of the general health. Some persons are very easily bruised. Discoloration-ecchymosis -may take place in the skin, cellular tissue, muscles, or internal organs. Not infrequently, the discoloration does not appear over the seat of injury, but at some distance from it; and when the effusion is deepseated, days may elapse before any discoloration of the skin takes place, and then it is not blue, as in