In case minute crystals of sulphate of iron and spots of rust are found, and the washings contain iron in a considerable quantity, _the weapon has been discharged at least twenty-four hours, at the longest ten days_. If the quantity of rust found is considerable, but iron is no longer to be detected, _the discharge of the gun occurred ten days, at the longest fifty days, previously_. _If the weapon has been reloaded immediately after its discharge without having been previously washed_, the portions of the wadding which have come in contact with the barrel will possess a greyish-black color during the first four days, the color gradually becoming lighter, until, at the fifteenth day, it turns grey and remains so permanently. In this case, the washings will contain sulphuric acid. The objection has been advanced to the last test that sulphuric acid might be discovered, even if the gun had not been discharged, if the paper of which the wadding was made contained plaster. M. Boutigny states, however, that this objection is untenable, if the wadding has not been moistened by the water introduced into the barrel. _In case the gun has been washed and dried before being reloaded_, the cylindrical portion of the wadding possesses an ochre-yellow color up to the first or second day, assumes a decided red hue on the days following, and acquires a clear rusty color on the sixth day. During the fifth day the powder also possesses a reddish appearance, owing to an admixture of rust. Sulphuric acid is not present in the washings. _If the weapon has been reloaded immediately after being washed_, the wadding possesses a greenish-yellow appearance for the first few hours, and subsequently acquires a reddish color, as in the preceding case. _If, finally, the barrel has been washed with turbid lime-water_, rust is still to be found and the wadding possesses the color mentioned above. The following colorations are also to be observed in case the gun has not been washed, or has been dried near a fire: BARREL DRIED NEAR A FIRE. UNWASHED BARREL. After 1 day slight reddish yellow color greenish yellow color. 2 or 3 days a little darker " reddish-brown " 4 days a redder " reddish-brown " 5 or more days a rusty-red " rusty-red. " THE GUN IS NOT PROVIDED WITH A FLINT LOCK.