The measurement of intensity of odour

Abstract

An instrument for the estimation of intensity of odour is described. The dilution required to make the odour just detectable in a mixture with odour‐free air is taken as a measure of the intensity, and the instrument is essentially a mechanical device for making the requisite dilution conveniently. Different persons show markedly different sensitivities to a given odour, and these differences vary widely with different odours. These differences in sensitivity cannot then be estimated from the results obtained with a particular ‘reference’ odour, but must be established from long‐term averages for the material concerned. Day‐to‐day variations in personal sensitivity, and other errors, were small compared with the residual error. Different persons exhibited widely different degrees of reliability in their results, and hence careful selection and training of those using these instruments is important.