A Guide to the diagnosis of occupational diseases : a reference manual for physicians / compiled jointly by the staffs of the Industrial Health Division Department of National Health and Welfare, and the Division of Industrial Hygiene, Department of Health for Ontario.

Date:
[1949]
Catalogue details

Licence: In copyright

Credit: A Guide to the diagnosis of occupational diseases : a reference manual for physicians / compiled jointly by the staffs of the Industrial Health Division Department of National Health and Welfare, and the Division of Industrial Hygiene, Department of Health for Ontario. Source: Wellcome Collection.

    15/328 (page 11)
    not tend to flocculate except under electrostatic forces; they do not diffuse in air but settle under the influence of gravity. (American Standards Association) FumEs: Solid particles generated by condensation from the gaseous state, generally after volatilization from molten metals, etc., and often accompanied by a chemical reaction such as oxidation. Fumes flocculate and sometimes coalesce. (ASA) Mists: Suspended liquid droplets generated by condensation from the gaseous to the liquid state or by breaking up a liquid into a dispersed state, such as by splashing, foaming, and atomizing. (ASA) Vapours: The gaseous form of substances which are normally in the solid or liquid state and which can be changed to these states either by increasing the pressure or decreasing the temperature alone. Vapours diffuse. (ASA) GaseEs: Normally formless fluids which occupy the space of enclo- sure and which can be changed to the liquid or solid state only by the combined effect of increased pressure and decreased temperature. Gases diffuse. (ASA) SPECIFIC GRAVITY: This is the density or weight of a liquid or solid in relation to that of water. When the liquid or solid is heavier than water, the specific gravity is greater than 1; when the substance is lighter than water, the specific gravity is less than 1. BorLinG Point: Thisis the temperature at which the vapour pres- sure of a liquid is equal to the atmospheric pressure. In general, the lower the boiling point of a liquid, the greater its vapour pressure at room temperature. VOLATILITY: This term is used to express the rate of evaporation of a liquid. Usually, the lower the boiling point of a liquid the more rapidly will it evaporate at room temperature. VAPOUR Density: This is the density or weight of a gas or vapour in relation to that of air. When the gas or vapour is heavier than air, the vapour density is greater than 1; when the substance is lighter than air the vapour density is less than 1. In still air, heavier gases and vapours tend to settle to lower levels, as for example, in pits and wells but a portion is diffused in the air at all levels.