At present weapons having flint-locks have almost entirely gone out of use and have been superseded by the ordinary percussion gun; these latter, in turn, are being gradually replaced by breech-loaders, charged with or without a metallic cartridge. The indications obtained in the preceding examinations by means of the fire-pan, will therefore disappear; the results given by the inspection of the barrel may possibly hold good. In regard to breech-loaders, all the useful indications furnished by the coloration of the wadding and powder fail to occur; the latter being enclosed either in a paper cylinder or in a copper socket. The fact that gun cotton and white gunpowder are occasionally made use of, adds to the difficulty of obtaining reliable results by the mere inspection of a weapon. White gunpowder does not oxidize the gun, fails to give rise to any salt of iron, and possesses a white color; gun-cotton produces distinctive indications varying with its purity. Owing to these facts, it is evident that the method proposed by M. Boutigny is of no real value, save in the rare instances where a gun provided with a fire-pan, and charged with ordinary powder, is under examination, and the question of the lapse of time since the discharge of a weapon must remain undetermined so far as scientific tests are concerned. DETECTION OF HUMAN REMAINS IN THE ASHES OF A FIRE-PLACE. This class of examinations is particularly necessary when the crime of infanticide is suspected. As the complete incineration of a cadaver is a long and difficult operation, it frequently occurs that bones--partially or completely carbonized, but retaining their original form--are discovered by the careful examination of the ashes of the fire-place in which the combustion was accomplished. When this is not the case and complete incineration and disaggregation have occurred, recourse must be had to the indications furnished by a chemical analysis. These indications are reliable, however, only when the certainty exists that bones of animals have not been consumed in the same fire-place; otherwise, the results obtained are entirely worthless, the reactions given by ashes of animal bones being identical with those produced by the ashes of a human body. Two tests are employed to detect the presence of bones in the residue left by the combustion of animal matter. 1. A portion of the ashes is placed in a silver crucible, heated with potassa, and the mass afterwards treated with cold water. If animal matter is contained in the consumed materials, cyanide of potassium will be present in the aqueous solution. In order to detect this salt, the fluid is acidulated with hydrochloric acid, and a solution of persulphate of iron added: the formation of a blue precipitate indicates the presence of the cyanide.