露点の知られている空気源

抄録

It is assumed that the dew point of the air passed through water as small bubbles is near the temperature of water. However, this fact is not proved experimentally, because of the difficulty of exact measurement of dew point.
When the temperature of air is varied under a constant pressure, the dew point of the air is kept unaltered. For the air of constant dew point, the temperature difference of psychrometer increases with the temperature of air. It is shown theoretically that the equi-dew-point curve near the dew point can be considered as a straight line. Therefore, the dew point of the air can be determined by finding the straight part of the equi-dew-point curve. For this purpose, the wet-and-dry-plate hygrometer can be employed suitably. The temperature of air passed through water is raised little by little from the temperature of bubbling water, and the relation between the temperature of air and the temperature difference is determined by the wet-and-dry-plate hygrometer. The intersecting point of the equi-dew-point curve and the temperature axis is the correct dew point. It is found experimentally that the straight part of the equi-dew-point curve extends to several degrees of the temperature difference. After the determiantion of the dew point, the ascertainment of the constancy of the dew point must be made by measuring the temperature and the temperature difference.
By the above mentioned method, the air of known dew point can be supplied continuously whether the air is saturated or not. It is experimentally shown that in some cases the bubbled air is not saturated with water vapour.