The Air‐Dilution Method of Odor Determination in Water Analysis

Abstract

The direct quantitative chemical determination of most of the substances that impart odors to drinking water is rendered difficult and generally impossible by the wide variety and structural complexity of these substances as well as by the minute magnitudes of the concentrations in which they are significant. If odors were radiant in nature rather than corpuscular, some method of electrical amplification might solve the problem. As matters stand, however, the human nose is, at present, the most sensitive detecting instrument at our disposal and is likely to remain so for some time to come. Hence all systems of odor determination in water analysis so far developed call into play the use of the sense of smell of the observer. To place the determination on a quantitative basis, stricter than the present estimates included in Standard Methods of Water Analysis, a system of dilution of the odorous water with odor-free water has been proposed by Spaulding (1) and a system of dilution with air of the odor emanating from the water has been suggested by Fair (2). It is the purpose of this paper to describe a new instrument devised to simplify the air-dilution method and possibly also the waterdilution method and to comment on the reasoning underlying its design.

The Reduction of Breath and Mouth Odors by Means of Brushing the Teeth

“…1. Brushing the teeth with a flavorless dentifrice will reduce odors on early morning breath 66 per cent, general mouth odors 30 per cent in aggregate.…”

Calculation of Threshold Odor

“…These chemicals are not commonly encountered, but their presence undoubtedly serves to explain occasional erratic test results. In the event that the water dilution method proves unsatisfactory with a given odor, recourse may be had to the air dilution method developed by Fair and Wells (8).…”

Studying the senses of taste and smell.

“…It is by the use of the double olfactometer that the interaction and neutralization of odors have been most extensively studied. Various modifications of this or similar principles have been developed for practical purposes [15]. In most of the procedures so far discussed, the subject draws the odorous vapor into the nostrils by inspiration.…”