Dyeing of Hair.--As a means of disguise the hair may be dyed, or the colour may be changed from dark to light. For darkening the hair, preparations containing permanganate of potash, or the acetate of lead, bismuth, or nitrate of silver, are most frequently employed. Sticks of nitrate of silver or lunar caustic are used for darkening eyebrows and moustachios. A wash containing sulphide of potassium is used before the application of the lead solution. This removes the grease, and helps the rapid formation of the black sulphide of lead. Preparations of henna are fashionable for the production of shades of copper to rich brown. To detect fraud, some of the suspected hair should be steeped in dilute nitric acid, the acid driven off by gentle heat, and the nitrate dissolved in distilled water, and then sulphuretted hydrogen passed through the solution, the result being the formation of the black sulphide of lead. If silver be present, the addition of hydrochloric acid will throw down the insoluble chloride of silver. If careful examination be made of dyed hair, it will be found that the dye is irregularly taken by the hair; the hair loses lustre, and I have not unfrequently seen the hair close to the scalp white, or at least several shades lighter than the rest. The scalp may also be seen more or less discoloured, especially when nitrate of silver is used and applied by the individual himself. For lightening the natural colour, solutions of chlorine, of peroxide of hydrogen, nitric and nitro-hydrochloric acids, of varying strengths, are used. It must be remembered that the action of chlorine is by no means uniform. The hair retains the odour of chlorine for some time, even after repeated washing, and is hard, stiff, and brittle. Devergie states that he has not succeeded in producing a perfect whitening of the hair in less than from twelve to twenty hours. It must be borne in mind that, under certain circumstances, dark hair may become suddenly white. I have seen large patches of grey hair over the head, the result of repeated attacks of neuralgia. In the examination of persons whose hair is alleged to have been dyed, it is necessary to compare the dyed hair with that from other parts of the body, _e.g._ the pubes, or axilla, to wait and watch for irregularities of colour as the hair grows, new growth being free from dye, and if necessary to shave the part and compare the new growth with other hair, also to examine carefully the skin in the position where the dye has been applied. In one case which I noted, a man had been in the habit of touching the moustachios and eyebrows with lunar caustic, having previously damped it with his tongue; in time it produced argyria which coloured the whole of his face, the body generally, but most noticeable on the face. [Illustration: Fig. 3.--Photo-micrograph of transverse section of normal hair follicle, × 250. (R. J. M. Buchanan.)] Examination of a Person said to have been Assaulted