from outward appearances, nor even from a dissection of the body, which, besides, could not be performed with safety to the surgeon and attendants, and that he therefore thought proper to decline the investigation. Fortunately for the ends of justice, the circumstantial evidence of guilt was too strong to be affected by this culpable defect in the medical testimony, although it has been often asserted that the prisoners should have received the benefit of the omission by an acquittal. See _Donellan’s_ case in the _Appendix_, p. 243. With respect to the mode of conducting a chemical analysis upon these occasions, we have reserved our directions, until we shall enter on the discussion of poisons individually. We have, however, in this place some remarks of a general nature to offer, to which we are desirous of drawing the attention of those, who, without much experience, may be called upon to conduct such investigations. In the first place, we are desirous of convincing him, that the processes which he must institute, for the detection of a mineral body, are by no means so elaborate and embarrassing, as a superficial view of the subject may lead him to conclude. During the progress of the present work the author has repeatedly felt the truth of the opinion which he is now expressing; for, like _Becher_, he has laid down his pen, and taken up his tests, and, by the most simple modes of manipulation, has satisfied his own mind of the extreme delicacy of the different processes which are recommended for the detection of a poisonous mineral; in short, it is very difficult to convince those whose chemical knowledge is wholly theoretical, with how little trouble, and with how much pleasure and profit, such experiments may be conducted. If such then be the perfect state at which our analytical knowledge has arrived, the reader may perhaps conclude, that _in every case of mineral poisoning the deleterious substance should be found, and that the inability of the chemist to detect its presence, should go far to negative the charge_. Such an inference, however, is neither correct, nor philosophical, for the poison may have been absorbed, or eliminated, during life, it may have undergone chemical changes, or it may have entered into combinations, by which its characters are masked, or wholly changed. To _Dr. Bostock_ the judicial physician is under many obligations, but there is no discovery for which he is more deeply indebted to him, than for that which has resulted from his satisfactory experiments, in elucidation of the present question. He has shewn, in the instance of _Corrosive Sublimate_,[199] that an animal may be suddenly killed by receiving a metallic poison into the stomach, and yet that the most delicate chemical re-agents may not be able to detect any portion of such poison, after death, in the contents of that viscus. _Dr. Henry_, in a letter to _Dr. Duncan_,[200] communicates the case of _Hannah