The investigation of mine air : an account by several authors of the nature, significance, and practical methods of measurement of the impurities met with in the air of collieries and metalliferous mines / edited by Clement le Neve Foster and J.S. Haldane.

  • Foster, Clement le Neve, Sir, 1841-1904.
Date:
1905
Catalogue details

Licence: In copyright

Credit: The investigation of mine air : an account by several authors of the nature, significance, and practical methods of measurement of the impurities met with in the air of collieries and metalliferous mines / edited by Clement le Neve Foster and J.S. Haldane. Source: Wellcome Collection.

Provider: This material has been provided by London School of Hygiene & Tropical Medicine Library & Archives Service. The original may be consulted at London School of Hygiene & Tropical Medicine Library & Archives Service.

    45/244 (page 25)
    large quantity, it first of all deadens the sense of smell and then causes unconsciousness, which passes over into death unless the person is quickly brought into fresh air. If fire-damp contains sulphuretted hydrogen, the after-damp will contain the product of its combustion, sulphur dioxide, easily recognisable by its characteristic pungent smell. 8. Aqueous Vapour. Aqueous vapour is always present in atinospheric air; its quantity is very variable, and is influenced by several factors, especially by the temperature. For each degree of temperature air can take up a certain maximum amount of moisture, the quantity of which can easily be reckoned from the tension of aqueous vapour at the temperature in question. Let/be the tension of the aqueoiis vapour at the temperature f, B the height of the barometer, expressed in millimetres of mercury: then ^^/= percentage of aqueous vapour by volume. B For instance, let ^ = 8° and B = 760 mm. In the case of complete saturation the quantity of aqueous vapour is 100 X 8-01 , „^ , , , —^^-^ =1-05 per cent, by volume. In reality this complete saturation is rarely reached. The absolute amount of moisture in the air can be most correctly determined by passing a measured volume of air over a suitable absorbent for water, such as dry chloride of calcium con- tained in a tube which is weighed before and after. The increase in weight gives the amount of water. In practice, it is usual merely to determine by means of the hygrometer the relative amount of moisture, that is to say, the proportion between the amount actually present and the highest possible amount at the temperature in question. If the relative amount of moisture is X per cent., then the actual amount of moisture W is deduced very simply from the equation— W = ^. B The amount of moisture in the air underground is almost always greater than in the air above ground, and in many collieries very