In a plurality of deaths occasioned by some common accident, as the falling of a building, an idea of survivorship may be deduced from an examination of the bodies, and of the relative situation in which they were found; it has been also said that if two persons are found dead in the water, and it be clearly made out that they were drowned, that besides the circumstantial presumptions afforded by evidence of greater buoyancy in the one body than in the other, or the knowledge that the one was a swimmer and the other not, we may by careful dissection surmise that death had supervened earlier in the one than in the other, from the appearances presented in the organs immediately acted on by this manner of death, such as _the presence of frothy mucus in the lungs, generated by vain attempts to respire_.[601] With regard to this latter test, we confess that we place no reliance whatever upon its indication, for it will be found to depend upon so many extraneous circumstances as to be incapable of affording any just grounds for a conclusion: equally futile is that opinion which would attach any importance to the thoracic capacity of the individuals in question. Where a number of persons have perished from the inhalation of impure air, we may perhaps be allowed to conclude that those nearest the doors or windows, survived those who were found where the noxious air must have been in its highest state of concentration. Medical Jurisprudence. PART III. INTRODUCTION. WE have at length arrived at the third, and most important division of our work, comprehending the consideration of the principal pleas of the crown, three of which, RAPE, ARSON, and MURDER, are pre-eminently the subjects of Medical Jurisprudence.