But a few words are required to introduce this volume. It is based on the two previous editions; but the complete revision, rendered necessary by time, has converted it into a new work. Like the preceding editions, it is not intended to be a complete history of Poisons and Poisoning. Its size will at once show that it can only comprise a small portion of a vast subject. It is, in fact, offered simply as a Manual for the use of students and practitioners in Law and Medicine, and therefore it has been kept within very moderate limits. Some substances described as poisons do not find a place here, simply for want of space, and on this, as on former occasions, I have exercised a freedom of selection with a special view to practice. As a rule I have omitted a description of those poisonous substances which have not hitherto given rise to investigations before our legal tribunals, and which are otherwise of little interest to the profession. In short, as the reader will perceive, the subject of poisons has been treated only in relation to Medical Jurisprudence and Medicine, and as fully as the space placed at my disposal would permit.<br><br>The whole work has been remodelled, and a number of illustrations have been introduced. Some chapters have been omitted, some divided, and others introduced, in accordance with the changing aspect of toxicological science. Quod hodie exemplis tuemur mox inter exempla erit.