PREFACE TO THE FOURTH EDITION. 
By expansion in some directions, condensation in others, the 
present edition contains more information, without material 
enlargement of the bulk of the volume, than the edition which 
immediately preceded it. 
A large portion has been rewritten, effete processes and 
unreliable reactions have been omitted. Newly discovered 
poisons and injurious substances which of recent years have 
come into popular use, such as sulphonal and trional, have been 
added. Space has been found for a condensed account of recent 
ideas as to the constitution of the vegetable poisons ; and we 
have felt that no work on toxicology would be complete without 
some mention of the most powerful of all modern poisons, 
i.e. epinephrin. 
Special attention has naturally been given to arsenic, and to 
the delicate and reliable methods which are now available for 
its separation, identification, and estimation. 
The authors hope that their labours have been so far success¬ 
ful that the new edition will retain its place as a recognised 
standard work on toxicology. 
3 UprER Gloucester Place, W., 
September 190G. 
