On Dust Counter. (I)

Abstract

An Owens' dust counter was used to measure the suspended impurity in air, and the results were compared with those obtained by a konimeter.
1) The numbers of the impurity by the former is less 30% ca. than the latter.
2) When we observe the impurity, such as soot or smoke, using Owens', as shown fig. 1 (b) remarkable coagurations between each particles are noticed in that preparation. Fig. 1 (a) is normal.
3) If we paint the cover glass of Owens' Dust Counter with grease, vaseline or canadabalsam, the result of the observation will be excellent.
4) As shown in fig. 2, the number of the dust particles is not distributed uniformly over the cover glass. This error is about 10%.