usually impractical and often impossible to isolate and identify the odor-producing chemical. Evaluation of odors and tastes is thus dependent on the chemical senses of smell and taste.
According to psychologists, there are only four true taste sensations, sour, sweet, salty and bitter. Dissolved inorganic salts of copper, iron, manganese, potassium, sodium and zinc can be detected by taste. Concentrations producing Caste range from a1 few to several hundred milligrams per liter. As these tastes are not ac companicd by odor, the taste test must be used where they are involved.