I feel it a great honour to have been invited to speak to so important a gathering of scientists on a subject, or rather part of a subject, in which for the past twenty-six years I have taken a particular interest.It is necessary at the present time to be very precise, and rather than use the ambiguous term “industrial health” I prefer to speak of the study of diseases attributable to occupation, a branch of medicine whose prestige was so high in the days of my late revered chief, Sir Thomas Legge, who had the art of moulding those who served him to his own likeness. Dr. Sybil Horner is the only member of Legge's crew left as a practising medical inspector to carry his ensign and preserve his tradition by combining, let us hope, the qualities of a Martha and of a Mary.Our terms of reference are the consideration of the relationship between certain chemical compounds or mixtures, especially pitch, tar, and tarry products including soot, encountered in certain occupations, in certain undertakings including factories; and one form of cancer, namely, an epithelioma, whether squamous celled, or basal celled (otherwise rodent ulcer) (Fig. 4), on the skin and its various sites.Certain authorities abroad apply the term epithelioma to both the malignant and the benign growth, whereas in this country we reserve it for the malignant stage, using the term “new growth, papillomatous, or keratotic” to denote the benign or precancerous stage.