Excerpt from the Preface--"The great progress which the art of perfumery has made during recent times is due to several causes, the chief one of which is fully realized only by the manufacturer on a large scale, who stands, as it were, behind the scenes and has access to facts and information concerning the materials he uses, which are not so easily accessible to the dilettante in perfumery, or remain altogether unknown to the latter. This important factor is the advance in our knowledge of the physical and chemical properties of the several substances used in perfumery, whereby we can better discriminate between the genuine and the spurious, the choicest and the inferior, thus insuring, at the very start, a satisfactory result, instead of being compelled to resort to wasteful experimentation and empiricism. A better knowledge has also been gained of the sources of the commercial varieties of many of the crude products, and a better insight into the conditions affecting their qualities or properties. "