EVALUATION OF ORAL ODOR :295 because it appears to have some limited usefulness in the analysis of odor bearing gases and because good stable high sensitivity densitometry equip- ment is becoming available. SUMMARY For the present and near future our best detector for the sensing of oral odor is the human nose. Quantification of the intensity of the odor pro- ducing gases requires a tool for controlling the amount of odor gas in a gas mixture. The Fair and Wells osmoscope is of value in the clinical evalua- tion of substances which are being tested for their odor controlling ability as long as the odor level is small. Strong odors cannot be tested with the Fair and Wells osmoscope because of the physiology and biophysics of olfaction. A dilution method is recommended for the odor analysis be- cause it is not limited in its range of operation. Objective methods are available for laboratory analysis of gases. However, these are of only limited value in the study of odors generated in the oral cavity. When more data become available through the use of gas chromatographic, in- frared and microspectrophotometric techniques, their applicability to oral odor analysis should increase. (Received September 25, 1963) REFERENCES (1) G. M. Fair and W. F. Wells. U.S. Patent No. 2,136,844 (1938). (2) W. H. Howell, In W. H. Howell, Textboo} o/_Physfofofy, 13th Ed. W.B. Saunders Co., Philadelphia, 1936. * Teflon FEP is the trademark for a fluorinated copolymer of ethylene and propylene E. I. du Pont de Nemours and Co., Inc.

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