liv Trans. Acad. Sci. of St. Louis. 



April 2, 1900. 



President Engler in the chair, twenty-six persons present. 



The resignations of Mr. W. P. Eberlein and Dr. Friedrich 

 Meier were reported by the Council. 



A paper by Dr. H. von Schrenk, entitled A severe sleet- 

 storm, and relating to a study of the injury to trees and shrubs 

 by an unusually severe recent ice storm, was presented and 

 read by title. 



Dr. W. H. Warren delivered an address on recent investi- 

 gations with reference to the production of perfumes, giving 

 an outline of the progress in the chemistry of these prod- 

 ucts. For the most part these substances are high boiling 

 oils. Formerly these oils, which are complex mixtures of 

 several compounds, were obtained exclusively from flowers, 

 but recently some of the essential principles have been pro- 

 duced by chemical means, whereas other artificial perfumes 

 are mere imitations. With a few exceptions the essential 

 principles, which give the perfumes their value, belong to a 

 complex class of organic compounds known as the terpenes. 

 The terpenes are the reduction products of cymol. The 

 molecule is characterized by the presence of an atomic linking 

 such as is found in the hydrocarbon ethylene, and the deter- 

 mination of the exact location of these ethylene linkings con- 

 stitutes a difficulty in studying the terpenes. 



It is found also that nearly every substance having the 

 properties of a perfume has in its molecule certain atomic 

 groups whose presence exerts a marked influence on the odor. 

 Among the more important of these may be mentioned the 

 aldehyde, ketone, ester, ether and alcohol group. 



Besides those terpenes, which have the ring-structure in 

 the molecule, there are substances which have long chains of 

 carbon atoms. Apparently such products should be classi- 

 fied with fatty compounds, but so closely do they resemble 

 the terpenes in their properties and chemical behavior that 

 they are placed with them instead. Citral or geranial, an 

 aldehyde found in largest quantity in oil of lemon-grass, is 

 such a substance. Citral is of importance because it is the 



