This book was very favourably reviewed, but from the criticisms made it was evident that something more was required and that there was room for a general textbook on the subject of Forensic Chemistry. The present book therefore has been written. Such portions of the previous book as dealt with criminal investigation have been revised and enlarged and incorporated in the present book and all matters not connected with criminal investigation have been deleted. Much of the present work, however, is new and, with the exception of its predecessor Legal Chemistry, it is believed to be the first of the kind in English. It is true that a book with the same title was published in 1909, but this, as was indicated by the sub-title, had particular reference to the presentation of general chemical evidence in Court, and not to methods Of obtaining the facts on which chemical evidence is based, much less to chemical methods of criminal investigation. Methods of examination and details of manipulation which are known to every analyst and which are to be found in the ordinary text-books have been omitted, but special methods required by the expert are given in full.