There may be a reddened appearance of the mucous membrane of the stomach and intestines, and in a certain number of cases, where death has occurred some time after the injuries, ulcers may be present in the duodenum. The uterus and testicles resist the action of fire in a marked degree, and may be changed but slightly, although the rest of the body has been almost consumed. The blood of persons who have been exposed to the action of CO during a fire will present the usual cherry-red colour and the spectrum of COHb. A similar cherry-red colour of the blood is found in bodies of persons burnt to death which is not due to the action of CO. The cause is a physical one, the alteration in colour being due to the coagulation of the albumin in microscopical particles by the heat. In this condition the spectrum is that of O₂Hb, and can be reduced in the usual way. The same peculiar condition of the blood may be produced in corpses by exposure to a sufficiently high temperature. If on the examination of the blood COHb is detected, it indicates that the person in whose body it is found was alive during the progress of the fire. _Corrosives._--The appearances produced by the application of corrosive chemical substances are peculiar to them, and depend upon their special actions upon the tissues. Sulphuric acid acts by rapidly extracting water from the tissues and producing local rise of temperature; nitric acid combines with the tissues to form picric acid; nitrate of silver acts upon the tissue by hyperoxidation, and combines to form albuminate of silver, nitric acid being liberated. A solution of phosphorus in carbon disulphide, known as Greek fire, by the rapid oxidation and burning of the phosphorus produces combustion of the tissues. The diagnosis of lesions produced by corrosives from those by fire or heated fluid or steam rests upon the absence of vesication, the presence of the stains on the skin or clothing which they produce, and the chemical analysis of the stains. Sulphuric acid produces a grey or brownish-black eschar on the body; hydrochloric acid may leave a whitish-grey stain; nitric acid produces a yellow stain on the skin, and may produce sloughing. =Was the burn inflicted before or after death?=--The answer to this question depends upon careful consideration of all the evidences afforded by the external and internal appearances, and upon the presence or absence of _vital reaction_ in the lesions found.