The attempt to systematise from the scientific standpoint the mass of material that has been collected about poisons is a very heavy task, even for the toxicologist who desires to treat his subject comprehensively. How much greater is the difficulty of writing a systematic book on industrial poisoning keeping practical application in the forefront!

Technical considerations which are decisive in the causation and prevention of industrial poisoning are here of especial moment, and must naturally influence classification of the subject-matter when the object is to assist those concerned in factory hygiene.

Bearing this in mind, I have divided the subject into three parts. The arrangement of the first, which gives as complete a statement as possible of the occurrence of industrial poisoning, into industries and processes was determined on technical grounds. The second, which amplifies the first, attempts to summarise the pathology or symptoms of the various forms of poisoning. The references to the literature of the particular subjects—as exhaustive as I could make them—will lighten further study. To these two parts, following on knowledge of causation and symptoms, the third, in which preventive measures are outlined, is linked.

The apparent drawback in use of the book is that one form of poisoning has often to be referred to in three places. But, I hope, this is more than counterbalanced by the completeness of the scheme which results from the subdivision of the subject.

The pathology of industrial poisoning necessitates frequent repetition when describing the branches of industry giving rise to the intoxication, as one and the same form can occur in the most varied processes. The numerous instances of actual cases of poisoning quoted must therefore be regarded as conforming to the same pathological type. Similarly, preventive measures require separate systematic treatment in order to avoid constant repetition which would otherwise obscure the general survey. Quite a number of means of prevention apply equally to several industries in which the same cause is at work. The success attained by thus simplifying the issues is the greater because such common measures are the easier to carry through and to supervise.

The method therefore has been adopted only after serious reflection and has been directed mainly by practical considerations.

Recent cases which have either been reported or come to the knowledge of the author have been given, with particulars as exact as possible. Cases dating back some time have been omitted intentionally so as to exclude everything which did not correspond with the present conditions of industry and trade. Historical facts only receive consideration in so far as they are fundamentally important and necessary for the sake of completeness.

The details given in Part I of actual instances will supply material for fresh efforts, renewed investigation, and new points of attack.